1
|
Jakešová M, Kunovský O, Gablech I, Khodagholy D, Gelinas J, Głowacki ED. Coupling of photovoltaics with neurostimulation electrodes-optical to electrolytic transduction. J Neural Eng 2024; 21:046003. [PMID: 38885680 DOI: 10.1088/1741-2552/ad593d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Accepted: 06/17/2024] [Indexed: 06/20/2024]
Abstract
Objective.The wireless transfer of power for driving implantable neural stimulation devices has garnered significant attention in the bioelectronics field. This study explores the potential of photovoltaic (PV) power transfer, utilizing tissue-penetrating deep-red light-a novel and promising approach that has received less attention compared to traditional induction or ultrasound techniques. Our objective is to critically assess key parameters for directly powering neurostimulation electrodes with PVs, converting light impulses into neurostimulation currents.Approach.We systematically investigate varying PV cell size, optional series configurations, and coupling with microelectrodes fabricated from a range of materials such as Pt, TiN, IrOx, Ti, W, PtOx, Au, or poly(3,4 ethylenedioxythiophene):poly(styrene sulfonate). Additionally, two types of PVs, ultrathin organic PVs and monocrystalline silicon PVs, are compared. These combinations are employed to drive pairs of electrodes with different sizes and impedances. The readout method involves measuring electrolytic current using a straightforward amplifier circuit.Main results.Optimal PV selection is crucial, necessitating sufficiently large PV cells to generate the desired photocurrent. Arranging PVs in series is essential to produce the appropriate voltage for driving current across electrode/electrolyte impedances. By carefully choosing the PV arrangement and electrode type, it becomes possible to emulate electrical stimulation protocols in terms of charge and frequency. An important consideration is whether the circuit is photovoltage-limited or photocurrent-limited. High charge-injection capacity electrodes made from pseudo-faradaic materials impose a photocurrent limit, while more capacitive materials like Pt are photovoltage-limited. Although organic PVs exhibit lower efficiency than silicon PVs, in many practical scenarios, stimulation current is primarily limited by the electrodes rather than the PV driver, leading to potential parity between the two types.Significance.This study provides a foundational guide for designing a PV-powered neurostimulation circuit. The insights gained are applicable to bothin vitroandin vivoapplications, offering a resource to the neural engineering community.
Collapse
Affiliation(s)
- Marie Jakešová
- Bioelectronics Materials and Devices Laboratory, Central European Institute of Technology CEITEC, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Ondřej Kunovský
- Bioelectronics Materials and Devices Laboratory, Central European Institute of Technology CEITEC, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Imrich Gablech
- Bioelectronics Materials and Devices Laboratory, Central European Institute of Technology CEITEC, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Dion Khodagholy
- Department of Electrical Engineering, Columbia University, New York, NY 10027, United States of America
| | - Jennifer Gelinas
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, United States of America
- Department of Neurology, Columbia University, New York, NY 10032, United States of America
| | - Eric Daniel Głowacki
- Bioelectronics Materials and Devices Laboratory, Central European Institute of Technology CEITEC, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| |
Collapse
|
2
|
Schulz A, Knoll T, Jaeger T, Le Harzic R, Stracke F, Wien SL, Olsommer Y, Meiser I, Wagner S, Rammensee M, Kurz O, Klesy S, Sermeus L, Julich-Haertel H, Schweitzer Y, Januschowski K, Velten T, Szurman P. Photovoltaic, wireless wide-field epiretinal prosthesis to treat retinitis pigmentosa. Acta Ophthalmol 2024. [PMID: 38923194 DOI: 10.1111/aos.16733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 06/11/2024] [Indexed: 06/28/2024]
Abstract
PURPOSE To develop and evaluate a photovoltaic, wireless wide-field epiretinal prosthesis for the treatment of retinitis pigmentosa. METHODS A mosaic array of thinned silicon-based photodiodes with integrated thin-film stimulation electrodes was fabricated with a flexible polyimide substrate film to form a film-based miniaturized electronic system with wireless optical power and signal transmission and integrated electrostimulation. Manufactured implants were characterized with respect to their optoelectronic performance and biocompatibility following DIN EN ISO 10993. RESULTS A 14 mm diameter prosthesis containing 1276 pixels with a maximum sensitivity at a near infrared wavelength of 905 nm and maximized stimulation current density 30-50 μm below the electrodes was developed for direct activation of retinal ganglion cells during epiretinal stimulation. Fabricated prostheses demonstrated mucosal tolerance and the preservation of both metabolic activity, proliferation and membrane integrity of human fibroblasts as well as the retinal functions of bovine retinas. Illumination of the prosthesis, which was placed epiretinally on an isolated perfused bovine retina, with infrared light resulted in electrophysiological recordings reminiscent of an a-wave (hyperpolarization) and b-wave (depolarization). CONCLUSIONS A photovoltaic, wireless wide-field epiretinal prosthesis for the treatment of retinitis pigmentosa using near infrared light for signal transmission was designed, manufactured and its biocompatibility and functionality demonstrated in vitro and ex vivo.
Collapse
Affiliation(s)
- André Schulz
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| | - Thorsten Knoll
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | | | - Ronan Le Harzic
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Frank Stracke
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Sascha L Wien
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Yves Olsommer
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Ina Meiser
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Sylvia Wagner
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | | | | | | | - Loic Sermeus
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
| | - Henrike Julich-Haertel
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| | | | - Kai Januschowski
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| | - Thomas Velten
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Peter Szurman
- Eye Clinic Sulzbach, Knappschaft Hospital Saar, Sulzbach, Germany
- Klaus Heimann Eye Research Institute, Sulzbach, Germany
| |
Collapse
|
3
|
Chung WG, Jang J, Cui G, Lee S, Jeong H, Kang H, Seo H, Kim S, Kim E, Lee J, Lee SG, Byeon SH, Park JU. Liquid-metal-based three-dimensional microelectrode arrays integrated with implantable ultrathin retinal prosthesis for vision restoration. NATURE NANOTECHNOLOGY 2024; 19:688-697. [PMID: 38225357 PMCID: PMC11106006 DOI: 10.1038/s41565-023-01587-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 11/28/2023] [Indexed: 01/17/2024]
Abstract
Electronic retinal prostheses for stimulating retinal neurons are promising for vision restoration. However, the rigid electrodes of conventional retinal implants can inflict damage on the soft retina tissue. They also have limited selectivity due to their poor proximity to target cells in the degenerative retina. Here we present a soft artificial retina (thickness, 10 μm) where flexible ultrathin photosensitive transistors are integrated with three-dimensional stimulation electrodes of eutectic gallium-indium alloy. Platinum nanoclusters locally coated only on the tip of these three-dimensional liquid-metal electrodes show advantages in reducing the impedance of the stimulation electrodes. These microelectrodes can enhance the proximity to the target retinal ganglion cells and provide effective charge injections (72.84 mC cm-2) to elicit neural responses in the retina. Their low Young's modulus (234 kPa), owing to their liquid form, can minimize damage to the retina. Furthermore, we used an unsupervised machine learning approach to effectively identify the evoked spikes to grade neural activities within the retinal ganglion cells. Results from in vivo experiments on a retinal degeneration mouse model reveal that the spatiotemporal distribution of neural responses on their retina can be mapped under selective localized illumination areas of light, suggesting the restoration of their vision.
Collapse
Affiliation(s)
- Won Gi Chung
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Jiuk Jang
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Gang Cui
- Institute of Vision Research, Department of Ophthalmology, Severance Eye Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Sanghoon Lee
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Han Jeong
- Institute of Vision Research, Department of Ophthalmology, Severance Eye Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Haisu Kang
- School of Chemical Engineering, Pusan National University, Busan, Republic of Korea
| | - Hunkyu Seo
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Sumin Kim
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Enji Kim
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea
| | - Junwon Lee
- Institute of Vision Research, Department of Ophthalmology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Seung Geol Lee
- School of Chemical Engineering, Pusan National University, Busan, Republic of Korea.
- Department of Organic Material Science and Engineering, Pusan National University, Busan, Republic of Korea.
| | - Suk Ho Byeon
- Institute of Vision Research, Department of Ophthalmology, Severance Eye Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea.
- Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, Republic of Korea.
| | - Jang-Ung Park
- Department of Materials Science & Engineering, Yonsei University, Seoul, Republic of Korea.
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea.
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, Republic of Korea.
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul, Republic of Korea.
| |
Collapse
|
4
|
Butt E, Wang BY, Shin A, Chen ZC, Bhuckory M, Shah S, Galambos L, Kamins T, Palanker D, Mathieson K. Three-dimensional electro-neural interfaces electroplated on subretinal prostheses. J Neural Eng 2024; 21:016030. [PMID: 38364290 PMCID: PMC10884765 DOI: 10.1088/1741-2552/ad2a37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/26/2024] [Accepted: 02/16/2024] [Indexed: 02/18/2024]
Abstract
Objective.Retinal prosthetics offer partial restoration of sight to patients blinded by retinal degenerative diseases through electrical stimulation of the remaining neurons. Decreasing the pixel size enables increasing prosthetic visual acuity, as demonstrated in animal models of retinal degeneration. However, scaling down the size of planar pixels is limited by the reduced penetration depth of the electric field in tissue. We investigated 3-dimensional (3d) structures on top of photovoltaic arrays for enhanced penetration of the electric field, permitting higher resolution implants.Approach.3D COMSOL models of subretinal photovoltaic arrays were developed to accurately quantify the electrodynamics during stimulation and verified through comparison to flat photovoltaic arrays. Models were applied to optimize the design of 3D electrode structures (pillars and honeycombs). Return electrodes on honeycomb walls vertically align the electric field with bipolar cells for optimal stimulation. Pillars elevate the active electrode, thus improving proximity to target neurons. The optimized 3D structures were electroplated onto existing flat subretinal prostheses.Main results.Simulations demonstrate that despite exposed conductive sidewalls, charge mostly flows via high-capacitance sputtered iridium oxide films topping the 3D structures. The 24μm height of honeycomb structures was optimized for integration with the inner nuclear layer cells in the rat retina, whilst 35μm tall pillars were optimized for penetrating the debris layer in human patients. Implantation of released 3D arrays demonstrates mechanical robustness, with histology demonstrating successful integration of 3D structures with the rat retinain-vivo.Significance. Electroplated 3D honeycomb structures produce vertically oriented electric fields, providing low stimulation thresholds, high spatial resolution, and high contrast for pixel sizes down to 20μm. Pillar electrodes offer an alternative for extending past the debris layer. Electroplating of 3D structures is compatible with the fabrication process of flat photovoltaic arrays, enabling much more efficient retinal stimulation.
Collapse
Affiliation(s)
- Emma Butt
- Institute of Photonics, Department of Physics, University of Strathclyde, Glasgow, United Kingdom
| | - Bing-Yi Wang
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
- Department of Physics, Stanford University, Stanford, CA, United States of America
| | - Andrew Shin
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, United States of America
| | - Zhijie Charles Chen
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Mohajeet Bhuckory
- Department of Ophthalmology, Stanford University, Stanford, CA, United States of America
| | - Sarthak Shah
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
| | - Ludwig Galambos
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Theodore Kamins
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America
- Department of Ophthalmology, Stanford University, Stanford, CA, United States of America
| | - Keith Mathieson
- Institute of Photonics, Department of Physics, University of Strathclyde, Glasgow, United Kingdom
| |
Collapse
|
5
|
Krishnan A, Deepak CS, Narayan KS. Investigations on artificially extending the spectral range of natural vision. APL Bioeng 2023; 7:046105. [PMID: 37886014 PMCID: PMC10599790 DOI: 10.1063/5.0156463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Accepted: 09/26/2023] [Indexed: 10/28/2023] Open
Abstract
Organic semiconductors are being explored as retinal prosthetics with the prime attributes of bio-compatibility and conformability for seamless integration with the retina. These polymer-based artificial photoreceptor films are self-powered with light-induced signal strength sufficient to elicit neuronal firing events. The molecular aspect of these semiconductors provides wide spectral tunability. Here, we present results from a bulk heterostructure semiconductor blend with a wide spectral response range. This combination elicits clear spiking activity from a developing blind-chick embryonic retina in the subretinal configuration in response to white light. The response is largely triggered by the blue-green spectral regime rather than the red-NIR regime for the present polymer semiconductor layer attributes.
Collapse
Affiliation(s)
- Abhijith Krishnan
- Chemistry and Physics of Materials Unit (CPMU), JNCASR, Bangalore, India
| | - C. S. Deepak
- Chemistry and Physics of Materials Unit (CPMU), JNCASR, Bangalore, India
| | | |
Collapse
|
6
|
Butt E, Wang BY, Shin A, Chen ZC, Bhuckory M, Shah S, Galambos L, Kamins T, Palanker D, Mathieson K. Three-dimensional electro-neural interfaces electroplated on subretinal prostheses. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.09.566003. [PMID: 38014082 PMCID: PMC10680680 DOI: 10.1101/2023.11.09.566003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Objective High-resolution retinal prosthetics offer partial restoration of sight to patients blinded by retinal degenerative diseases through electrical stimulation of the remaining neurons. Decreasing the pixel size enables an increase in prosthetic visual acuity, as demonstrated in animal models of retinal degeneration. However, scaling down the size of planar pixels is limited by the reduced penetration depth of the electric field in tissue. We investigate 3-dimensional structures on top of the photovoltaic arrays for enhanced penetration of electric field to permit higher-resolution implants. Approach We developed 3D COMSOL models of subretinal photovoltaic arrays that accurately quantify the device electrodynamics during stimulation and verified it experimentally through comparison with the standard (flat) photovoltaic arrays. The models were then applied to optimise the design of 3D electrode structures (pillars and honeycombs) to efficiently stimulate the inner retinal neurons. The return electrodes elevated on top of the honeycomb walls surrounding each pixel orient the electric field inside the cavities vertically, aligning it with bipolar cells for optimal stimulation. Alternatively, pillars elevate the active electrode into the inner nuclear layer, improving proximity to the target neurons. Modelling results informed a microfabrication process of electroplating the 3D electrode structures on top of the existing flat subretinal prosthesis. Main results Simulations demonstrate that despite the conductive sidewalls of the 3D electrodes being exposed to electrolyte, most of the charge flows via the high-capacitance sputtered Iridium Oxide film that caps the top of the 3D structures. The 24 μm height of the electroplated honeycomb structures was optimised for integration with the inner nuclear layer cells in rat retina, while 35 μm height of the pillars was optimized for penetrating the debris layer in human patients. Release from the wafer and implantation of the 3D arrays demonstrated that they are mechanically robust to withstand the associated forces. Histology demonstrated successful integration of the 3D structures with the rat retina in-vivo. Significance Electroplated 3D honeycomb structures produce a vertically oriented electric field that offers low stimulation threshold, high spatial resolution and high contrast for the retinal implants with pixel sizes down to 20μm in width. Pillar electrodes offer an alternative configuration for extending the stimulation past the debris layers. Electroplating of the 3D structures is compatible with the fabrication process of the flat photovoltaic arrays, thereby enabling much more efficient stimulation than in their original flat configuration.
Collapse
Affiliation(s)
- Emma Butt
- Institute of Photonics, Department of Physics, University of Strathclyde, Glasgow, Scotland, UK
| | - Bing-Yi Wang
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Andrew Shin
- Department of Materials Science and Engineering, Stanford, CA, USA
| | - Zhijie Charles Chen
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | | | - Sarthak Shah
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
| | - Ludwig Galambos
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Theodore Kamins
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Keith Mathieson
- Institute of Photonics, Department of Physics, University of Strathclyde, Glasgow, Scotland, UK
| |
Collapse
|
7
|
Almasri RM, Ladouceur F, Mawad D, Esrafilzadeh D, Firth J, Lehmann T, Poole-Warren LA, Lovell NH, Al Abed A. Emerging trends in the development of flexible optrode arrays for electrophysiology. APL Bioeng 2023; 7:031503. [PMID: 37692375 PMCID: PMC10491464 DOI: 10.1063/5.0153753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 08/08/2023] [Indexed: 09/12/2023] Open
Abstract
Optical-electrode (optrode) arrays use light to modulate excitable biological tissues and/or transduce bioelectrical signals into the optical domain. Light offers several advantages over electrical wiring, including the ability to encode multiple data channels within a single beam. This approach is at the forefront of innovation aimed at increasing spatial resolution and channel count in multichannel electrophysiology systems. This review presents an overview of devices and material systems that utilize light for electrophysiology recording and stimulation. The work focuses on the current and emerging methods and their applications, and provides a detailed discussion of the design and fabrication of flexible arrayed devices. Optrode arrays feature components non-existent in conventional multi-electrode arrays, such as waveguides, optical circuitry, light-emitting diodes, and optoelectronic and light-sensitive functional materials, packaged in planar, penetrating, or endoscopic forms. Often these are combined with dielectric and conductive structures and, less frequently, with multi-functional sensors. While creating flexible optrode arrays is feasible and necessary to minimize tissue-device mechanical mismatch, key factors must be considered for regulatory approval and clinical use. These include the biocompatibility of optical and photonic components. Additionally, material selection should match the operating wavelength of the specific electrophysiology application, minimizing light scattering and optical losses under physiologically induced stresses and strains. Flexible and soft variants of traditionally rigid photonic circuitry for passive optical multiplexing should be developed to advance the field. We evaluate fabrication techniques against these requirements. We foresee a future whereby established telecommunications techniques are engineered into flexible optrode arrays to enable unprecedented large-scale high-resolution electrophysiology systems.
Collapse
Affiliation(s)
- Reem M. Almasri
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | | | - Damia Mawad
- School of Materials Science and Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Dorna Esrafilzadeh
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Josiah Firth
- Australian National Fabrication Facility, UNSW, Sydney, NSW 2052, Australia
| | - Torsten Lehmann
- School of Electrical Engineering and Telecommunications, UNSW, Sydney, NSW 2052, Australia
| | | | | | - Amr Al Abed
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| |
Collapse
|
8
|
Borchert GA, Shamsnajafabadi H, Hu ML, De Silva SR, Downes SM, MacLaren RE, Xue K, Cehajic-Kapetanovic J. The Role of Inflammation in Age-Related Macular Degeneration-Therapeutic Landscapes in Geographic Atrophy. Cells 2023; 12:2092. [PMID: 37626902 PMCID: PMC10453093 DOI: 10.3390/cells12162092] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 07/28/2023] [Accepted: 08/11/2023] [Indexed: 08/27/2023] Open
Abstract
Age-related macular degeneration (AMD) is the leading cause of vision loss and visual impairment in people over 50 years of age. In the current therapeutic landscape, intravitreal anti-vascular endothelial growth factor (anti-VEGF) therapies have been central to the management of neovascular AMD (also known as wet AMD), whereas treatments for geographic atrophy have lagged behind. Several therapeutic approaches are being developed for geographic atrophy with the goal of either slowing down disease progression or reversing sight loss. Such strategies target the inflammatory pathways, complement cascade, visual cycle or neuroprotective mechanisms to slow down the degeneration. In addition, retinal implants have been tried for vision restoration and stem cell therapies for potentially a dual purpose of slowing down the degeneration and restoring visual function. In particular, therapies focusing on the complement pathway have shown promising results with the FDA approved pegcetacoplan, a complement C3 inhibitor, and avacincaptad pegol, a complement C5 inhibitor. In this review, we discuss the mechanisms of inflammation in AMD and outline the therapeutic landscapes of atrophy AMD. Improved understanding of the various pathway components and their interplay in this complex neuroinflammatory degeneration will guide the development of current and future therapeutic options, such as optogenetic therapy.
Collapse
Affiliation(s)
- Grace A. Borchert
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
| | - Hoda Shamsnajafabadi
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
| | - Monica L. Hu
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
| | - Samantha R. De Silva
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Susan M. Downes
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, Oxford OX3 9DU, UK
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences, Oxford University, Oxford OX3 9DU, UK
- Oxford Eye Hospital, Oxford University NHS Foundation Trust, Oxford OX3 9DU, UK
| |
Collapse
|
9
|
Spencer M, Kameneva T, Grayden DB, Burkitt AN, Meffin H. Quantifying visual acuity for pre-clinical testing of visual prostheses. J Neural Eng 2023; 20. [PMID: 36270430 DOI: 10.1088/1741-2552/ac9c95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 10/21/2022] [Indexed: 01/31/2023]
Abstract
Objective.Visual prostheses currently restore only limited vision. More research and pre-clinical work are required to improve the devices and stimulation strategies that are used to induce neural activity that results in visual perception. Evaluation of candidate strategies and devices requires an objective way to convert measured and modelled patterns of neural activity into a quantitative measure of visual acuity.Approach.This study presents an approach that compares evoked patterns of neural activation with target and reference patterns. A d-prime measure of discriminability determines whether the evoked neural activation pattern is sufficient to discriminate between the target and reference patterns and thus provides a quantified level of visual perception in the clinical Snellen and MAR scales. The magnitude of the resulting value was demonstrated using scaled standardized 'C' and 'E' optotypes.Main results.The approach was used to assess the visual acuity provided by two alternative stimulation strategies applied to simulated retinal implants with different electrode pitch configurations and differently sized spreads of neural activity. It was found that when there is substantial overlap in neural activity generated by different electrodes, an estimate of acuity based only upon electrode pitch is incorrect; our proposed method gives an accurate result in both circumstances.Significance.Quantification of visual acuity using this approach in pre-clinical development will allow for more rapid and accurate prototyping of improved devices and neural stimulation strategies.
Collapse
Affiliation(s)
- Martin Spencer
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia.,Greame Clark Institute of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Tatiana Kameneva
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia.,School of Science, Computing and Engineering Technologies, Swinburne University of Technology, Hawthorn, Victoria, Australia
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia.,Greame Clark Institute of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Anthony N Burkitt
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia.,Greame Clark Institute of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Hamish Meffin
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia.,Greame Clark Institute of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia.,National Vision Research Institute, Australian College of Optometry, Carlton, Victoria, Australia
| |
Collapse
|
10
|
Steins H, Mierzejewski M, Brauns L, Stumpf A, Kohler A, Heusel G, Corna A, Herrmann T, Jones PD, Zeck G, von Metzen R, Stieglitz T. A flexible protruding microelectrode array for neural interfacing in bioelectronic medicine. MICROSYSTEMS & NANOENGINEERING 2022; 8:131. [PMID: 36568135 PMCID: PMC9772315 DOI: 10.1038/s41378-022-00466-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 06/23/2022] [Accepted: 07/07/2022] [Indexed: 05/31/2023]
Abstract
Recording neural signals from delicate autonomic nerves is a challenging task that requires the development of a low-invasive neural interface with highly selective, micrometer-sized electrodes. This paper reports on the development of a three-dimensional (3D) protruding thin-film microelectrode array (MEA), which is intended to be used for recording low-amplitude neural signals from pelvic nervous structures by penetrating the nerves transversely to reduce the distance to the axons. Cylindrical gold pillars (Ø 20 or 50 µm, ~60 µm height) were fabricated on a micromachined polyimide substrate in an electroplating process. Their sidewalls were insulated with parylene C, and their tips were optionally modified by wet etching and/or the application of a titanium nitride (TiN) coating. The microelectrodes modified by these combined techniques exhibited low impedances (~7 kΩ at 1 kHz for Ø 50 µm microelectrode with the exposed surface area of ~5000 µm²) and low intrinsic noise levels. Their functionalities were evaluated in an ex vivo pilot study with mouse retinae, in which spontaneous neuronal spikes were recorded with amplitudes of up to 66 µV. This novel process strategy for fabricating flexible, 3D neural interfaces with low-impedance microelectrodes has the potential to selectively record neural signals from not only delicate structures such as retinal cells but also autonomic nerves with improved signal quality to study neural circuits and develop stimulation strategies in bioelectronic medicine, e.g., for the control of vital digestive functions.
Collapse
Affiliation(s)
- Helen Steins
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
| | - Michael Mierzejewski
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Lisa Brauns
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Angelika Stumpf
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Alina Kohler
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Gerhard Heusel
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Andrea Corna
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | - Thoralf Herrmann
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Peter D. Jones
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Günther Zeck
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | - Rene von Metzen
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Thomas Stieglitz
- Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany
- Bernstein Center Freiburg, University of Freiburg, Freiburg, Germany
- BrainLinks-BrainTools, University of Freiburg, Freiburg, Germany
| |
Collapse
|
11
|
Cojocaru AE, Corna A, Reh M, Zeck G. High spatial resolution artificial vision inferred from the spiking output of retinal ganglion cells stimulated by optogenetic and electrical means. Front Cell Neurosci 2022; 16:1033738. [PMID: 36568888 PMCID: PMC9780279 DOI: 10.3389/fncel.2022.1033738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/10/2022] [Indexed: 12/13/2022] Open
Abstract
With vision impairment affecting millions of people world-wide, various strategies aiming at vision restoration are being undertaken. Thanks to decades of extensive research, electrical stimulation approaches to vision restoration began to undergo clinical trials. Quite recently, another technique employing optogenetic therapy emerged as a possible alternative. Both artificial vision restoration strategies reported poor spatial resolution so far. In this article, we compared the spatial resolution inferred ex vivo under ideal conditions using a computational model analysis of the retinal ganglion cell (RGC) spiking activity. The RGC spiking was stimulated in epiretinal configuration by either optogenetic or electrical means. RGCs activity was recorded from the ex vivo retina of transgenic late-stage photoreceptor-degenerated mice (rd10) using a high-density Complementary Metal Oxide Semiconductor (CMOS) based microelectrode array. The majority of retinal samples were stimulated by both, optogenetic and electrical stimuli using a spatial grating stimulus. A population-level analysis of the spiking activity of identified RGCs was performed and the spatial resolution achieved through electrical and optogenetic photo-stimulation was inferred using a support vector machine classifier. The best f1 score of the classifier for the electrical stimulation in epiretinal configuration was 86% for 32 micron wide gratings and increased to 100% for 128 microns. For optogenetically activated cells, we obtained high f1 scores of 82% for 10 microns grid width for a photo-stimulation frequency of 2.5 Hz and 73% for a photo-stimulation frequency of 10 Hz. A subsequent analysis, considering only the RGCs modulated in both electrical and optogenetic stimulation protocols revealed no significant difference in the prediction accuracy between the two stimulation modalities. The results presented here indicate that a high spatial resolution can be achieved for electrical or optogenetic artificial stimulation using the activated retinal ganglion cell output.
Collapse
Affiliation(s)
| | - Andrea Corna
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| | - Miriam Reh
- Institute for Ophthalmic Research at the University of Tübingen, Tübingen, Germany
| | - Günther Zeck
- Institute of Biomedical Electronics, TU Wien, Vienna, Austria
| |
Collapse
|
12
|
de Bougrenet de la Tocnaye JL. Restored vision-augmented vision: arguments for a cybernetic vision. C R Biol 2022; 345:135-156. [PMID: 36847468 DOI: 10.5802/crbiol.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022]
Abstract
In this paper, we present some thoughts about the recent developments, made possible by technological advances and miniaturisation of connected visual prostheses, linked to the visual system, operating at different level of this one, on the retina as well as in the visual cortex. While these objects represent a great hope for people with impaired vision to recover partial vision, we show how this technology could also act on the functional vision of well sighted persons to improve or increase their visual performance. In addition to the impact on our cognitive and attentional mechanisms, such an operation when it originates outside the natural real visual field (e.g. cybernetics) raises a number of questions about the development and use of such implants or prostheses in the future.
Collapse
|
13
|
Jeong H, Kim J, Seo JM, Neviani A. Neurostimulators for high-resolution artificial retina: ASIC design challenges and solutions. J Neural Eng 2022; 19. [PMID: 36374010 DOI: 10.1088/1741-2552/aca262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 11/14/2022] [Indexed: 11/16/2022]
Abstract
Objective.Neurostimulator is one of the most important part in artificial retina design. In this paper, we discuss the main challenges in the design of application-specific integrated circuit for high-resolution artificial retina and suggest corresponding solutions.Approach. Problems in the design of the neurostimulator for the existing artificial retina have not been solved yet are analyzed and solutions are presented. For verification of the solutions, mathematical proof, MATLAB and Ansys simulations are used.Main results. The drawbacks of resorting to a high-voltage complementary metal oxide semiconductor (CMOS) process to deal with the large voltage compliance demanded by the stimulator output stage are pointed out, and an alternative approach based on a circuit that switches the voltage of the common reference electrode is proposed to overcome. The necessity of an active discharge circuit to remove the residual charge of electrodes caused by an unbalanced stimulus is investigated. We present a circuit analysis showing that the use of a passive discharge circuit is sufficient to suppress problematic direct current in most situations. Finally, possible restrictions on input and output (I/O) count are investigated by estimating the resistive-capacitive delay caused by the interconnection between the I/O pad and the microelectrode array.Significance. The results of this paper clarified the problems currently faced by neurostimulator design for the artificial retina. Through the solutions presented in this study, circuits with more competitiveness in power and area consumption can be designed.
Collapse
Affiliation(s)
- Hyunbeen Jeong
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Jisung Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Jong-Mo Seo
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea.,Department of Ophthalmology, Seoul National University Hospital, Seoul, Republic of Korea
| | - Andrea Neviani
- Department of Information Engineering, University of Padova, Padova, Italy
| |
Collapse
|
14
|
Carleton M, Oesch NW. Differences in the spatial fidelity of evoked and spontaneous signals in the degenerating retina. Front Cell Neurosci 2022; 16:1040090. [PMID: 36419935 PMCID: PMC9676928 DOI: 10.3389/fncel.2022.1040090] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 10/20/2022] [Indexed: 07/01/2024] Open
Abstract
Vision restoration strategies aim to reestablish vision by replacing the function of lost photoreceptors with optoelectronic hardware or through gene therapy. One complication to these approaches is that retinal circuitry undergoes remodeling after photoreceptor loss. Circuit remodeling following perturbation is ubiquitous in the nervous system and understanding these changes is crucial for treating neurodegeneration. Spontaneous oscillations that arise during retinal degeneration have been well-studied, however, other changes in the spatiotemporal processing of evoked and spontaneous activity have received less attention. Here we use subretinal electrical stimulation to measure the spatial and temporal spread of both spontaneous and evoked activity during retinal degeneration. We found that electrical stimulation synchronizes spontaneous oscillatory activity, over space and through time, thus leading to increased correlations in ganglion cell activity. Intriguingly, we found that spatial selectivity was maintained in rd10 retina for evoked responses, with spatial receptive fields comparable to wt retina. These findings indicate that different biophysical mechanisms are involved in mediating feed forward excitation, and the lateral spread of spontaneous activity in the rd10 retina, lending support toward the possibility of high-resolution vision restoration.
Collapse
Affiliation(s)
- Maya Carleton
- Department of Psychology, University of California, San Diego, La Jolla, CA, United States
| | - Nicholas W. Oesch
- Department of Psychology, University of California, San Diego, La Jolla, CA, United States
- Department of Ophthalmology, University of California, San Diego, La Jolla, CA, United States
- The Neurosciences Graduate Program, University of California, San Diego, La Jolla, CA, United States
| |
Collapse
|
15
|
Huang Y, Cui Y, Deng H, Wang J, Hong R, Hu S, Hou H, Dong Y, Wang H, Chen J, Li L, Xie Y, Sun P, Fu X, Yin L, Xiong W, Shi SH, Luo M, Wang S, Li X, Sheng X. Bioresorbable thin-film silicon diodes for the optoelectronic excitation and inhibition of neural activities. Nat Biomed Eng 2022; 7:486-498. [PMID: 36065014 DOI: 10.1038/s41551-022-00931-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 07/25/2022] [Indexed: 11/09/2022]
Abstract
Neural activities can be modulated by leveraging light-responsive nanomaterials as interfaces for exerting photothermal, photoelectrochemical or photocapacitive effects on neurons or neural tissues. Here we show that bioresorbable thin-film monocrystalline silicon pn diodes can be used to optoelectronically excite or inhibit neural activities by establishing polarity-dependent positive or negative photovoltages at the semiconductor/solution interface. Under laser illumination, the silicon-diode optoelectronic interfaces allowed for the deterministic depolarization or hyperpolarization of cultured neurons as well as the upregulated or downregulated intracellular calcium dynamics. The optoelectronic interfaces can also be mounted on nerve tissue to activate or silence neural activities in peripheral and central nervous tissues, as we show in mice with exposed sciatic nerves and somatosensory cortices. Bioresorbable silicon-based optoelectronic thin films that selectively excite or inhibit neural tissue may find advantageous biomedical applicability.
Collapse
Affiliation(s)
- Yunxiang Huang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Institute for Precision Medicine, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China.,School of Materials Science and Engineering, The Key Laboratory of Advanced Materials of Ministry of Education, State Key Laboratory of New Ceramics and Fine Processing, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China.,IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China
| | - Yuting Cui
- Chinese Institute for Brain Research, Beijing, China.,National Institute of Biological Sciences, Beijing, China
| | - Hanjie Deng
- CAS Key Laboratory of Brain Connectome and Manipulation, the Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Jingjing Wang
- CAS Key Laboratory of Brain Connectome and Manipulation, the Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Rongqi Hong
- CAS Key Laboratory of Brain Connectome and Manipulation, the Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Shuhan Hu
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Hanqing Hou
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Yuanrui Dong
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, China
| | - Huachun Wang
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Institute for Precision Medicine, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Junyu Chen
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Institute for Precision Medicine, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Lizhu Li
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Institute for Precision Medicine, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Yang Xie
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Institute for Precision Medicine, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Pengcheng Sun
- School of Materials Science and Engineering, The Key Laboratory of Advanced Materials of Ministry of Education, State Key Laboratory of New Ceramics and Fine Processing, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Xin Fu
- School of Materials Science and Engineering, The Key Laboratory of Advanced Materials of Ministry of Education, State Key Laboratory of New Ceramics and Fine Processing, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Lan Yin
- School of Materials Science and Engineering, The Key Laboratory of Advanced Materials of Ministry of Education, State Key Laboratory of New Ceramics and Fine Processing, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Wei Xiong
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Song-Hai Shi
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Minmin Luo
- IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China.,Chinese Institute for Brain Research, Beijing, China.,National Institute of Biological Sciences, Beijing, China.,School of Life Sciences, Tsinghua University, Beijing, China
| | - Shirong Wang
- Beijing Advanced Innovation Center for Intelligent Robots and Systems, Beijing Institute of Technology, Beijing, China.
| | - Xiaojian Li
- CAS Key Laboratory of Brain Connectome and Manipulation, the Brain Cognition and Brain Disease Institute (BCBDI), Shenzhen Institute of Advanced Technology, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.
| | - Xing Sheng
- Department of Electronic Engineering, Beijing National Research Center for Information Science and Technology, Institute for Precision Medicine, Center for Flexible Electronics Technology, Tsinghua University, Beijing, China. .,IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing, China.
| |
Collapse
|
16
|
Shi L, Jiang Y, Zheng N, Cheng JX, Yang C. High-precision neural stimulation through optoacoustic emitters. NEUROPHOTONICS 2022; 9:032207. [PMID: 35355658 PMCID: PMC8941197 DOI: 10.1117/1.nph.9.3.032207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 02/25/2022] [Indexed: 05/03/2023]
Abstract
Neuromodulation poses an invaluable role in deciphering neural circuits and exploring clinical treatment of neurological diseases. Optoacoustic neuromodulation is an emerging modality benefiting from the merits of ultrasound with high penetration depth as well as the merits of photons with high spatial precision. We summarize recent development in a variety of optoacoustic platforms for neural modulation, including fiber, film, and nanotransducer-based devices, highlighting the key advantages of each platform. The possible mechanisms and main barriers for optoacoustics as a viable neuromodulation tool are discussed. Future directions in fundamental and translational research are proposed.
Collapse
Affiliation(s)
- Linli Shi
- Boston University, Department of Chemistry, Boston, Massachusetts, United States
| | - Ying Jiang
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
| | - Nan Zheng
- Boston University, Division of Materials Science and Engineering, Boston, Massachusetts, United States
| | - Ji-Xin Cheng
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts, United States
- Address all correspondence to Chen Yang, ; Ji-Xin Cheng,
| | - Chen Yang
- Boston University, Department of Chemistry, Boston, Massachusetts, United States
- Boston University, Department of Electrical and Computer Engineering, Boston, Massachusetts, United States
- Address all correspondence to Chen Yang, ; Ji-Xin Cheng,
| |
Collapse
|
17
|
Deepak CS, Krishnan A, Narayan KS. Light Controlled Signaling Initiated by Subretinal Semiconducting-Polymer Layer in Developing-Blind-Retina Mimics the Response of the Neonatal Retina. J Neural Eng 2022; 19. [PMID: 35561667 DOI: 10.1088/1741-2552/ac6f80] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 05/13/2022] [Indexed: 11/11/2022]
Abstract
Optoelectronic semiconducting polymer material interfaced with a blind-developing chick-retina (E13-E18) in subretinal configuration reveals a response to full-field flash stimulus that resembles an elicited response from natural photoreceptors in a mature chick retina. The response manifests as evoked-firing of action potentials was recorded using a multi-electrode array in contact with the retinal ganglion layer. Characteristics of increasing features in the signal unfold during different retina-development stages and highlight the emerging network mediated pathways typically present in the vision process of the artificial photoreceptor interfaced retina.
Collapse
Affiliation(s)
- C S Deepak
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Center for Advanced Scientific Research, Molecular Electronics Lab, Bangalore, Karnataka, 560064, INDIA
| | - Abhijith Krishnan
- Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Molecular Electronics Lab, Bangalore, Karnataka, 560064, INDIA
| | - K S Narayan
- Neuroscience Unit, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), JNCASR, Bangalore, Karnataka, 560064, INDIA
| |
Collapse
|
18
|
Avraham D, Yitzhaky Y. Simulating the perceptual effects of electrode-retina distance in prosthetic vision. J Neural Eng 2022; 19. [PMID: 35561665 DOI: 10.1088/1741-2552/ac6f82] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 05/13/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Retinal prostheses aim to restore some vision in retinitis pigmentosa and age-related macular degeneration blind patients. Many spatial and temporal aspects have been found to affect prosthetic vision. Our objective is to study the impact of the space-variant distance between the stimulating electrodes and the surface of the retina on prosthetic vision and how to mitigate this impact. APPROACH A prosthetic vision simulation was built to demonstrate the perceptual effects of the electrode-retina distance (ERD) with different random spatial variations, such as size, brightness, shape, dropout, and spatial shifts. Three approaches for reducing the ERD effects are demonstrated: electrode grouping (quads), ERD-based input-image enhancement, and object scanning with and without phosphene persistence. A quantitative assessment for the first two approaches was done based on experiments with 20 subjects and three vision-based computational image similarity metrics. MAIN RESULTS The effects of various ERDs on phosphenes' size, brightness, and shape were simulated. Quads, chosen according to the ERDs, effectively elicit phosphenes without exceeding the safe charge density limit, whereas single electrodes with large ERD cannot do so. Input-image enhancement reduced the ERD effects effectively. These two approaches significantly improved ERD-affected prosthetic vision according to the experiment and image similarity metrics. A further reduction of the ERD effects was achieved by scanning an object while moving the head. SIGNIFICANCE ERD has multiple effects on perception with retinal prostheses. One of them is vision loss caused by the incapability of electrodes with large ERD to evoke phosphenes. The three approaches presented in this study can be used separately or together to mitigate the impact of ERD. A consideration of our approaches in reducing the perceptual effects of the ERD may help improve the perception with current prosthetic technology and influence the design of future prostheses.
Collapse
Affiliation(s)
- David Avraham
- Department of Electro-Optical Engineering, Ben-Gurion University of the Negev, 1 Ben-Gurion Blvd., Beer-Sheva, 84105, ISRAEL
| | - Yitzhak Yitzhaky
- Electro-Optical Engineering, School of Engineering, Ben-Gurion University of the Negev, 1 Ben-Gurion Blvd., Beer-Sheva, Southern, 84105, ISRAEL
| |
Collapse
|
19
|
Sharf T, Kalakuntla T, J Lee D, Gokoffski KK. Electrical devices for visual restoration. Surv Ophthalmol 2022; 67:793-800. [PMID: 34487742 PMCID: PMC9241872 DOI: 10.1016/j.survophthal.2021.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 08/24/2021] [Accepted: 08/30/2021] [Indexed: 11/21/2022]
Abstract
Given the rising number of patients with blindness from macular, optic nerve, and visual pathway disease, there is considerable interest in the potential of electrical stimulation devices to restore vision. Electrical devices for restoration of visual function can be grouped into three categories: (1) visual prostheses whose goal is to bypass damaged areas and directly activate downstream intact portions of the visual pathway; (2) electric field stimulation whose goal is to activate endogenous transcriptional and molecular signaling pathways to promote neuroprotection and neuro-regeneration; and (3) neuromodulation whose stimulation would resuscitate neural circuits vital to coordinating responses to visual input. In this review, we discuss these three approaches, describe advances made in the different fields, and comment on limitations and potential future directions.
Collapse
Affiliation(s)
- Tamara Sharf
- Keck School of Medicine, University of Southern California, CA, USA
| | - Tej Kalakuntla
- Keck School of Medicine, University of Southern California, CA, USA
| | - Darrin J Lee
- Department of Neurological Surgery, University of Southern California, CA, USA
| | - Kimberly K Gokoffski
- Department of Ophthalmology, Roski Eye Institute, University of Southern California, CA, USA.
| |
Collapse
|
20
|
Nikić M, Opančar A, Hartmann F, Migliaccio L, Jakešová M, Głowacki ED, Đerek V. Micropyramid structured photo capacitive interfaces. NANOTECHNOLOGY 2022; 33:245302. [PMID: 35226885 DOI: 10.1088/1361-6528/ac5927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Optically driven electronic neuromodulation devices are a novel tool in basic research and offer new prospects in medical therapeutic applications. Optimal operation of such devices requires efficient light capture and charge generation, effective electrical communication across the device's bioelectronic interface, conformal adhesion to the target tissue, and mechanical stability of the device during the lifetime of the implant-all of which can be tuned by spatial structuring of the device. We demonstrate a 3D structured opto-bioelectronic device-an organic electrolytic photocapacitor spatially designed by depositing the active device layers on an inverted micropyramid-shaped substrate. Ultrathin, transparent, and flexible micropyramid-shaped foil was fabricated by chemical vapour deposition of parylene C on silicon moulds containing arrays of inverted micropyramids, followed by a peel-off procedure. The capacitive current delivered by the devices showed a strong dependency on the underlying spatial structure. The device performance was evaluated by numerical modelling. We propose that the developed numerical model can be used as a basis for the design of future functional 3D design of opto-bioelectronic devices and electrodes.
Collapse
Affiliation(s)
- Marta Nikić
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, 10000, Zagreb, Croatia
| | - Aleksandar Opančar
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, 10000, Zagreb, Croatia
| | - Florian Hartmann
- Soft Matter Physics, Institute of Experimental Physics, Johannes Kepler University Linz, Altenberger Strasse 69, Linz, A-4040, Austria
- Soft Materials Lab, Linz Institute of Technology LIT, Johannes Kepler University, Altenberger Strasse 69, Linz, A-4040, Austria
| | - Ludovico Migliaccio
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Marie Jakešová
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Eric Daniel Głowacki
- Central European Institute of Technology, Brno University of Technology, Purkyňova 123, 61200 Brno, Czech Republic
| | - Vedran Đerek
- Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, 10000, Zagreb, Croatia
| |
Collapse
|
21
|
Vėbraitė I, Hanein Y. Soft Devices for High-Resolution Neuro-Stimulation: The Interplay Between Low-Rigidity and Resolution. FRONTIERS IN MEDICAL TECHNOLOGY 2022; 3:675744. [PMID: 35047928 PMCID: PMC8757739 DOI: 10.3389/fmedt.2021.675744] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 05/14/2021] [Indexed: 12/27/2022] Open
Abstract
The field of neurostimulation has evolved over the last few decades from a crude, low-resolution approach to a highly sophisticated methodology entailing the use of state-of-the-art technologies. Neurostimulation has been tested for a growing number of neurological applications, demonstrating great promise and attracting growing attention in both academia and industry. Despite tremendous progress, long-term stability of the implants, their large dimensions, their rigidity and the methods of their introduction and anchoring to sensitive neural tissue remain challenging. The purpose of this review is to provide a concise introduction to the field of high-resolution neurostimulation from a technological perspective and to focus on opportunities stemming from developments in materials sciences and engineering to reduce device rigidity while optimizing electrode small dimensions. We discuss how these factors may contribute to smaller, lighter, softer and higher electrode density devices.
Collapse
Affiliation(s)
- Ieva Vėbraitė
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel
| | - Yael Hanein
- School of Electrical Engineering, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
22
|
Cho YH, Park YG, Kim S, Park JU. 3D Electrodes for Bioelectronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2005805. [PMID: 34013548 DOI: 10.1002/adma.202005805] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/04/2020] [Indexed: 05/08/2023]
Abstract
In recent studies related to bioelectronics, significant efforts have been made to form 3D electrodes to increase the effective surface area or to optimize the transfer of signals at tissue-electrode interfaces. Although bioelectronic devices with 2D and flat electrode structures have been used extensively for monitoring biological signals, these 2D planar electrodes have made it difficult to form biocompatible and uniform interfaces with nonplanar and soft biological systems (at the cellular or tissue levels). Especially, recent biomedical applications have been expanding rapidly toward 3D organoids and the deep tissues of living animals, and 3D bioelectrodes are getting significant attention because they can reach the deep regions of various 3D tissues. An overview of recent studies on 3D bioelectronic devices, such as the use of electrical stimulations and the recording of neural signals from biological subjects, is presented. Subsequently, the recent developments in materials and fabrication processing to 3D micro- and nanostructures are introduced, followed by broad applications of these 3D bioelectronic devices at various in vitro and in vivo conditions.
Collapse
Affiliation(s)
- Yo Han Cho
- Nano Science Technology Institute, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, 03722, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, 03722, Republic of Korea
| | - Young-Geun Park
- Nano Science Technology Institute, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, 03722, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, 03722, Republic of Korea
| | - Sumin Kim
- Nano Science Technology Institute, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, 03722, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jang-Ung Park
- Nano Science Technology Institute, Department of Materials Science and Engineering, Yonsei University, Seoul, 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, 03722, Republic of Korea
- Graduate Program of Nano Biomedical Engineering (NanoBME), Advanced Science Institute, Yonsei University, Seoul, 03722, Republic of Korea
| |
Collapse
|
23
|
Damle S, Carleton M, Kapogianis T, Arya S, Cavichini-Corderio M, Freeman WR, Lo YH, Oesch NW. Minimizing Iridium Oxide Electrodes for High Visual Acuity Subretinal Stimulation. eNeuro 2021; 8:ENEURO.0506-20.2021. [PMID: 34799411 PMCID: PMC8704424 DOI: 10.1523/eneuro.0506-20.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 10/28/2021] [Accepted: 11/15/2021] [Indexed: 11/21/2022] Open
Abstract
Vision loss from diseases of the outer retina, such as age-related macular degeneration, is among the leading causes of irreversible blindness in the world today. The goal of retinal prosthetics is to replace the photo-sensing function of photoreceptors lost in these diseases with optoelectronic hardware to electrically stimulate patterns of retinal activity corresponding to vision. To enable high-resolution retinal prosthetics, the scale of stimulating electrodes must be significantly decreased from current designs; however, this reduces the amount of stimulating current that can be delivered. The efficacy of subretinal stimulation at electrode sizes suitable for high visual acuity retinal prosthesis are not well understood, particularly within the safe charge injection limits of electrode materials. Here, we measure retinal ganglion cell (RGC) responses in a mouse model of blindness to evaluate the stimulation efficacy of 10, 20, and 30 μm diameter iridium oxide electrodes within the electrode charge injection limits, focusing on measures of charge threshold and dynamic range. Stimulation thresholds were lower for smaller electrodes, but larger electrodes could elicit a greater dynamic range of spikes and recruited more ganglion cells within charge injection limits. These findings suggest a practical lower limit for planar electrode size and indicate strategies for maximizing stimulation thresholds and dynamic range.
Collapse
Affiliation(s)
- Samir Damle
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093
| | - Maya Carleton
- Department of Psychology, University of California San Diego, La Jolla, CA 92093
| | - Theodoros Kapogianis
- Department of Psychology, University of California San Diego, La Jolla, CA 92093
| | - Shaurya Arya
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92161
| | - Melina Cavichini-Corderio
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093
| | - William R Freeman
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093
| | - Yu-Hwa Lo
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92161
| | - Nicholas W Oesch
- Department of Psychology, University of California San Diego, La Jolla, CA 92093
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, La Jolla, CA 92093
| |
Collapse
|
24
|
Xu Y, Pang S. Microelectrode Array With Integrated Pneumatic Channels for Dynamic Control of Electrode Position in Retinal Implants. IEEE Trans Neural Syst Rehabil Eng 2021; 29:2292-2298. [PMID: 34705653 DOI: 10.1109/tnsre.2021.3123754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Retinal prostheses are biomedical devices that directly utilize electrical stimulation to create an artificial vision to help patients with retinal diseases such as retinitis pigmentosa. A major challenge in the microelectrode array (MEA) design for retinal prosthesis is to have a close topographical fit on the retinal surface. The local retinal topography can cause the electrodes in certain areas to have gaps up to several hundred micrometers from the retinal surface, resulting in impaired, or totally lost electrode functions in specific areas of the MEA. In this manuscript, an MEA with dynamically controlled electrode positions was proposed to reduce the electrode-retina distance and eliminate areas with poor contact after implantation. The MEA prototype had a polydimethylsiloxane and polyimide hybrid flexible substrate with gold interconnect lines and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate electrodes. Ring shaped counter electrodes were placed around the main electrodes to measure the distance between the electrode and the model retinal surface in real time. The results showed that this MEA design could reduce electrode-retina distance up to [Formula: see text] with 200 kPa pressure. Meanwhile, the impedance between the main and counter electrodes increased with smaller electrode-model retinal surface distance. Thus, the change of electrode-counter electrode impedance could be used to measure the separation gap and to confirm successful electrode contact without the need of optical coherence tomography scan. The amplitude of the stimulation signal on the model retinal surface with originally poor contact could be significantly improved after pressure was applied to reduce the gap.
Collapse
|
25
|
Abstract
Visual retinal prostheses aim to restore vision for blind individuals who suffer from outer retinal degenerative diseases, such as retinitis pigmentosa and age-related macular degeneration. Perception through retinal prostheses is very limited, but it can be improved by applying object isolation. We used an object isolation algorithm based on integral imaging to isolate objects of interest according to their depth from the camera and applied image processing manipulation to the isolated-object images. Subsequently, we applied a spatial prosthetic vision simulation that converted the isolated-object images to phosphene images. We compared the phosphene images for two types of input images, the original image (before applying object isolation), and the isolated-object image to illustrate the effects of object isolation on simulated prosthetic vision without and with multiple spatial variations of phosphenes, such as size and shape variations, spatial shifts, and dropout rate. The results show an improvement in the perceived shape, contrast, and dynamic range (number of gray levels) of objects in the phosphene image.
Collapse
|
26
|
Shi L, Jiang Y, Fernandez FR, Chen G, Lan L, Man HY, White JA, Cheng JX, Yang C. Non-genetic photoacoustic stimulation of single neurons by a tapered fiber optoacoustic emitter. LIGHT, SCIENCE & APPLICATIONS 2021; 10:143. [PMID: 34257273 PMCID: PMC8277806 DOI: 10.1038/s41377-021-00580-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 06/09/2021] [Accepted: 06/21/2021] [Indexed: 05/19/2023]
Abstract
Neuromodulation at high spatial resolution poses great significance in advancing fundamental knowledge in the field of neuroscience and offering novel clinical treatments. Here, we developed a tapered fiber optoacoustic emitter (TFOE) generating an ultrasound field with a high spatial precision of 39.6 µm, enabling optoacoustic activation of single neurons or subcellular structures, such as axons and dendrites. Temporally, a single acoustic pulse of sub-microsecond converted by the TFOE from a single laser pulse of 3 ns is shown as the shortest acoustic stimuli so far for successful neuron activation. The precise ultrasound generated by the TFOE enabled the integration of the optoacoustic stimulation with highly stable patch-clamp recording on single neurons. Direct measurements of the electrical response of single neurons to acoustic stimulation, which is difficult for conventional ultrasound stimulation, have been demonstrated. By coupling TFOE with ex vivo brain slice electrophysiology, we unveil cell-type-specific responses of excitatory and inhibitory neurons to acoustic stimulation. These results demonstrate that TFOE is a non-genetic single-cell and sub-cellular modulation technology, which could shed new insights into the mechanism of ultrasound neurostimulation.
Collapse
Affiliation(s)
- Linli Shi
- Department of Chemistry, Boston University, 580 Commonwealth Avenue, Boston, MA, 02215, USA
| | - Ying Jiang
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
| | - Fernando R Fernandez
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Ave, Boston, MA, 02215, USA
- Neurophotonics Center, Photonics Center, Boston University, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Guo Chen
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Lu Lan
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Heng-Ye Man
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Ave, Boston, MA, 02215, USA
- Department of Biology, Boston University, 5 Cummington Mall, Boston, MA, 02215, USA
| | - John A White
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA
- Center for Systems Neuroscience, Boston University, 610 Commonwealth Ave, Boston, MA, 02215, USA
- Neurophotonics Center, Photonics Center, Boston University, 8 St. Mary's Street, Boston, MA, 02215, USA
| | - Ji-Xin Cheng
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA.
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA.
| | - Chen Yang
- Department of Chemistry, Boston University, 580 Commonwealth Avenue, Boston, MA, 02215, USA.
- Department of Electrical and Computer Engineering, 8 St. Mary's Street, Boston, MA, 02215, USA.
| |
Collapse
|
27
|
Sadeghi R, Kartha A, Barry MP, Bradley C, Gibson P, Caspi A, Roy A, Dagnelie G. Glow in the dark: Using a heat-sensitive camera for blind individuals with prosthetic vision. Vision Res 2021; 184:23-29. [PMID: 33780753 PMCID: PMC8137663 DOI: 10.1016/j.visres.2021.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 02/12/2021] [Accepted: 02/28/2021] [Indexed: 11/29/2022]
Abstract
To date, retinal implants are the only available treatment for blind individuals with retinal degenerations such as retinitis pigmentosa. Argus II is the only visual implant with FDA approval, with more than 300 users worldwide. Argus II stimulation is based on a grayscale image coming from a head-mounted visible-light camera. Normally, the 11°×19° field of view of the Argus II user is full of objects that may elicit similar phosphenes. The prosthesis cannot meaningfully convey so much visual information, and the percept is reduced to an ambiguous impression of light. This study is aimed at investigating the efficacy of simplifying the video input in real-time using a heat-sensitive camera. Data were acquired from four Argus II users in 5 stationary tasks with either hot objects or human targets as stimuli. All tasks were of m-alternative forced choice design where precisely one of the m≥2 response alternatives was defined to be "correct" by the experimenter. To compare performance with heat-sensitive and normal cameras across all tasks, regardless of m, we used an extension of signal detection theory to latent variables, estimating person ability and item difficulty in d' units. Results demonstrate that subject performance was significantly better across all tasks with the thermal camera compared to the regular Argus II camera. The future addition of thermal imaging to devices with very poor spatial resolution may have significant real-life benefits for orientation, personal safety, and social interactions, thereby improving quality of life.
Collapse
Affiliation(s)
- Roksana Sadeghi
- Department of Biomedical Engineering, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Arathy Kartha
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | | | - Chris Bradley
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Paul Gibson
- Advanced Medical Electronics Corporation, Maple Grove, MN, USA
| | - Avi Caspi
- Second Sight Medical Products, Sylmar, CA, USA; Jerusalem College of Technology, Jerusalem, Israel
| | - Arup Roy
- Second Sight Medical Products, Sylmar, CA, USA
| | - Gislin Dagnelie
- Department of Ophthalmology, Johns Hopkins School of Medicine, Baltimore, MD, USA
| |
Collapse
|
28
|
Xie H, Wang Y, Ye Z, Fang S, Xu Z, Wu T, Chan LLH. Monitoring Cortical Response and Electrode-Retina Impedance Under Epiretinal Stimulation in Rats. IEEE Trans Neural Syst Rehabil Eng 2021; 29:1178-1187. [PMID: 34152987 DOI: 10.1109/tnsre.2021.3090904] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Retinal prosthesis can restore partial vision in patients with retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. Epiretinal prosthesis is one of three therapeutic approaches, which received regulatory approval several years ago. The thresholds of an epiretinal stimulation is partly determined by the size of the physical gap between the electrode and the retina after implantation. Precise positioning of epiretinal stimulating electrode array is still a challenging task. In this study, we demonstrate an approach to positioning epiretinal prostheses for an optimal response at the cortical output by monitoring both the impedance at the electrode-retina interface and the evoked-potential at the cortical level. We implanted a single-channel electrode on the epiretinal surface in adult rats, acutely, guided by both the impedance at the electrode-retina interface and by electrically evoked potentials (EEPs) in the visual cortex during retinal stimulation. We observe that impedance monotonously increases with decreasing electrode-retina distance, but that the strongest cortical responses were achieved at intermediate impedance levels. When the electrode penetrates the retina, the impedance keeps increasing. The effect of stimulation on the retina changes from epiretinal paradigm to intra-retinal paradigm and a decrease in cortical activation is observed. It is found that high impedance is not always favorable to elicit best cortical responses. Histopathological results showed that the electrode was placed at the intra-retinal space at high impedance value. These results show that monitoring impedance at the electrode-retina interface is necessary but not sufficient in obtaining strong evoked-potentials at the cortical level. Monitoring the cortical EEPs together with the impedance can improve the safety of implantation as well as efficacy of stimulation in the next generation of retinal implants.
Collapse
|
29
|
Moleirinho S, Whalen AJ, Fried SI, Pezaris JS. The impact of synchronous versus asynchronous electrical stimulation in artificial vision. J Neural Eng 2021; 18. [PMID: 33900206 DOI: 10.1088/1741-2552/abecf1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 03/09/2021] [Indexed: 11/12/2022]
Abstract
Visual prosthesis devices designed to restore sight to the blind have been under development in the laboratory for several decades. Clinical translation continues to be challenging, due in part to gaps in our understanding of critical parameters such as how phosphenes, the electrically-generated pixels of artificial vision, can be combined to form images. In this review we explore the effects that synchronous and asynchronous electrical stimulation across multiple electrodes have in evoking phosphenes. Understanding how electrical patterns influence phosphene generation to control object binding and perception of visual form is fundamental to creation of a clinically successful prosthesis.
Collapse
Affiliation(s)
- Susana Moleirinho
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America
| | - Andrew J Whalen
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America
| | - Shelley I Fried
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America.,Boston VA Healthcare System, Boston, MA, United States of America
| | - John S Pezaris
- Department of Neurosurgery, Massachusetts General Hospital, Boston, MA, United States of America.,Department of Neurosurgery, Harvard Medical School, Boston, MA, United States of America
| |
Collapse
|
30
|
Bilteanu L, Geicu OI, Stanca L, Pisoschi AM, Serban F, Serban AI, Calu V. Human Eye Optics within a Non-Euclidian Geometrical Approach and Some Implications in Vision Prosthetics Design. Biomolecules 2021; 11:215. [PMID: 33557081 PMCID: PMC7913825 DOI: 10.3390/biom11020215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 11/25/2022] Open
Abstract
An analogy with our previously published theory on the ionospheric auroral gyroscope provides a new perspective in human eye optics. Based on cone cells' real distribution, we model the human eye macula as a pseudospherical surface. This allows the rigorous description of the photoreceptor cell densities in the parafoveal zones modeled further by an optimized paving method. The hexagonal photoreceptors' distribution has been optimally projected on the elliptical pseudosphere, thus designing a prosthetic array counting almost 7000 pixel points. Thanks to the high morphological similarities to a normal human retina, the visual prosthesis performance in camera-free systems might be significantly improved.
Collapse
Affiliation(s)
- Liviu Bilteanu
- Department of Preclinic Sciences, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 105 Blvd. Splaiul Independentei, 050097 Bucharest, Romania; (L.B.); (O.I.G.); (L.S.); (A.M.P.); (F.S.)
- Molecular Nanotechnology Laboratory, National Institute for Research and Development in Microtechnologies, 126A, Erou Iancu Nicolae Street, 077190 Bucharest, Romania
| | - Ovidiu I. Geicu
- Department of Preclinic Sciences, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 105 Blvd. Splaiul Independentei, 050097 Bucharest, Romania; (L.B.); (O.I.G.); (L.S.); (A.M.P.); (F.S.)
| | - Loredana Stanca
- Department of Preclinic Sciences, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 105 Blvd. Splaiul Independentei, 050097 Bucharest, Romania; (L.B.); (O.I.G.); (L.S.); (A.M.P.); (F.S.)
| | - Aurelia M. Pisoschi
- Department of Preclinic Sciences, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 105 Blvd. Splaiul Independentei, 050097 Bucharest, Romania; (L.B.); (O.I.G.); (L.S.); (A.M.P.); (F.S.)
| | - Florea Serban
- Department of Preclinic Sciences, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 105 Blvd. Splaiul Independentei, 050097 Bucharest, Romania; (L.B.); (O.I.G.); (L.S.); (A.M.P.); (F.S.)
| | - Andreea I. Serban
- Department of Preclinic Sciences, Faculty of Veterinary Medicine, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 105 Blvd. Splaiul Independentei, 050097 Bucharest, Romania; (L.B.); (O.I.G.); (L.S.); (A.M.P.); (F.S.)
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, 91-95 Blvd. Splaiul Independentei, 050095 Bucharest, Romania
| | - Valentin Calu
- Department of General Surgery, University of Medicine and Pharmacy “Carol Davila” Bucharest, 8 Blvd. Eroii Sanitari, 050474 Bucharest, Romania;
| |
Collapse
|
31
|
Shah NP, Chichilnisky EJ. Computational challenges and opportunities for a bi-directional artificial retina. J Neural Eng 2020; 17:055002. [PMID: 33089827 DOI: 10.1088/1741-2552/aba8b1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A future artificial retina that can restore high acuity vision in blind people will rely on the capability to both read (observe) and write (control) the spiking activity of neurons using an adaptive, bi-directional and high-resolution device. Although current research is focused on overcoming the technical challenges of building and implanting such a device, exploiting its capabilities to achieve more acute visual perception will also require substantial computational advances. Using high-density large-scale recording and stimulation in the primate retina with an ex vivo multi-electrode array lab prototype, we frame several of the major computational problems, and describe current progress and future opportunities in solving them. First, we identify cell types and locations from spontaneous activity in the blind retina, and then efficiently estimate their visual response properties by using a low-dimensional manifold of inter-retina variability learned from a large experimental dataset. Second, we estimate retinal responses to a large collection of relevant electrical stimuli by passing current patterns through an electrode array, spike sorting the resulting recordings and using the results to develop a model of evoked responses. Third, we reproduce the desired responses for a given visual target by temporally dithering a diverse collection of electrical stimuli within the integration time of the visual system. Together, these novel approaches may substantially enhance artificial vision in a next-generation device.
Collapse
Affiliation(s)
- Nishal P Shah
- Department of Electrical Engineering, Stanford University, Stanford, CA, United States of America. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, United States of America. Department of Neurosurgery, Stanford University, Stanford, CA, United States of America. Author to whom any correspondence should be addressed
| | | |
Collapse
|
32
|
Batabyal S, Gajjeraman S, Pradhan S, Bhattacharya S, Wright W, Mohanty S. Sensitization of ON-bipolar cells with ambient light activatable multi-characteristic opsin rescues vision in mice. Gene Ther 2020; 28:162-176. [PMID: 33087861 DOI: 10.1038/s41434-020-00200-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/11/2020] [Accepted: 09/29/2020] [Indexed: 12/19/2022]
Abstract
Gene therapy-based treatment such as optogenetics offers a potentially powerful way to bypass damaged photoreceptors in retinal degenerative diseases and use the remaining retinal cells for functionalization to achieve photosensitivity. However, current approaches of optogenetic treatment rely on opsins that require high intensity light for activation thus adding to the challenge for use as part of a wearable device. Here, we report AAV2 assisted delivery of highly photosensitive multi-characteristic opsin (MCO1) into ON-bipolar cells of mice with retinal degeneration to allow activation by ambient light. Rigorous characterization of delivery efficacy by different doses of AAV2 carrying MCO1 (vMCO1) into targeted cells showed durable expression over 6 months after delivery as measured by reporter expression. The enduring MCO1 expression was correlated with the significantly improved behavioral outcome, that was longitudinally measured by visual water-maze and optomotor assays. The pro/anti-inflammatory cytokine levels in plasma and vitreous humor of the vMCO1-injected group did not change significantly from baseline or control group. Furthermore, biodistribution studies at various time points after injection in animal groups injected with different doses of vMCO1 showed non-detectable vector copies in non-targeted tissues. Immunohistochemistry of vMCO1 transfected retinal tissues showed bipolar specific expression of MCO1 and the absence of immune/inflammatory response. Furthermore, ocular imaging using SD-OCT showed no change in the structural architecture of vMCO1-injected eyes. Induction of ambient light responsiveness to remaining healthy bipolar cells in subjects with retinal degeneration will allow the retinal circuitry to gain visual acuity without requiring an active stimulation device.
Collapse
|
33
|
Ahnood A, Cheriton R, Bruneau A, Belcourt JA, Ndabakuranye JP, Lemaire W, Hilkes R, Fontaine R, Cook JPD, Hinzer K, Prawer S. Laser Driven Miniature Diamond Implant for Wireless Retinal Prostheses. ACTA ACUST UNITED AC 2020; 4:e2000055. [PMID: 33084251 DOI: 10.1002/adbi.202000055] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 09/03/2020] [Indexed: 01/16/2023]
Abstract
The design and benchtop operation of a wireless miniature epiretinal stimulator implant is reported. The implant is optically powered and controlled using safe illumination at near-infrared wavelengths. An application-specific integrated circuit (ASIC) hosting a digital control unit is used to control the implant's electrodes. The ASIC is powered using an advanced photovoltaic (PV) cell and programmed using a single photodiode. Diamond packaging technology is utilized to achieve high-density integration of the implant optoelectronic circuitry, as well as individual connections between a stimulator chip and 256 electrodes, within a 4.6 mm × 3.7 mm × 0.9 mm implant package. An ultrahigh efficiency PV cell with a monochromatic power conversion efficiency of 55% is used to power the implant. On-board photodetection circuity with a bandwidth of 3.7 MHz is used for forward data telemetry of stimulation parameters. In comparison to implants which utilize inductively coupled coils, laser power delivery enables a high degree of miniaturization and lower surgical complexity. The device presented combines the benefits of implant miniaturization and a flexible stimulation strategy provided by a dedicated stimulator chip. This development provides a route to fully wireless miniaturized minimally invasive implants with sophisticated functionalities.
Collapse
Affiliation(s)
- Arman Ahnood
- School of Physics, University of Melbourne, Parkville, VIC, 3010, Australia.,School of Engineering, RMIT University, Melbourne, VIC, 3000, Australia
| | - Ross Cheriton
- National Research Council of Canada, Ottawa, ON, K1A 0R6, Canada.,iBIONICS, Ottawa, ON, K2H 8S9, Canada
| | | | - James A Belcourt
- School of Physics, University of Melbourne, Parkville, VIC, 3010, Australia
| | | | - William Lemaire
- Interdisciplinary Institute for Technological Innovation, Université de Sherbrooke, Sherbrooke, QC, J1K 0A5, Canada
| | - Rob Hilkes
- iBIONICS, Ottawa, ON, K2H 8S9, Canada.,Gezell Inc. Gatineau, Gatineau, QC, J9A1L8, Canada
| | - Réjean Fontaine
- Interdisciplinary Institute for Technological Innovation, Université de Sherbrooke, Sherbrooke, QC, J1K 0A5, Canada
| | - John P D Cook
- Centre for Research in Photonics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Karin Hinzer
- Centre for Research in Photonics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Steven Prawer
- School of Physics, University of Melbourne, Parkville, VIC, 3010, Australia
| |
Collapse
|
34
|
Srivastava SB, Melikov R, Yildiz E, Han M, Sahin A, Nizamoglu S. Efficient photocapacitors via ternary hybrid photovoltaic optimization for photostimulation of neurons. BIOMEDICAL OPTICS EXPRESS 2020; 11:5237-5248. [PMID: 33014611 PMCID: PMC7510852 DOI: 10.1364/boe.396068] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/16/2020] [Accepted: 08/03/2020] [Indexed: 05/31/2023]
Abstract
Optoelectronic photoelectrodes based on capacitive charge-transfer offer an attractive route to develop safe and effective neuromodulators. Here, we demonstrate efficient optoelectronic photoelectrodes that are based on the incorporation of quantum dots (QDs) into poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-Phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction. We control the performance of the photoelectrode by the blend ratio, thickness, and nanomorphology of the ternary bulk heterojunction. The optimization led to a photocapacitor that has a photovoltage of 450 mV under a light intensity level of 20 mW.cm-2 and a responsivity of 99 mA/W corresponding to the most light-sensitive organic photoelectrode reported to date. The photocapacitor can facilitate action potential generation by hippocampal neurons via burst waveforms at an intensity level of 20 mW.cm-2. Therefore, the results point to an alternative direction in the engineering of safe and ultra-light-sensitive neural interfaces.
Collapse
Affiliation(s)
| | - Rustamzhon Melikov
- Department of Electrical and Electronics Engineering, Koc University, Istanbul 34450, Turkey
| | - Erdost Yildiz
- Koc University Research Center for Translational Medicine, Koc University, Istanbul 34450, Turkey
| | - Mertcan Han
- Department of Electrical and Electronics Engineering, Koc University, Istanbul 34450, Turkey
| | - Afsun Sahin
- Koc University Research Center for Translational Medicine, Koc University, Istanbul 34450, Turkey
- Department of Ophthalmology, Medical School, Koc University, Istanbul 34450, Turkey
| | - Sedat Nizamoglu
- Department of Electrical and Electronics Engineering, Koc University, Istanbul 34450, Turkey
- Graduate School of Biomedical Sciences and Engineering, Koc University, Istanbul 34450, Turkey
| |
Collapse
|
35
|
Nowik K, Langwińska-Wośko E, Skopiński P, Nowik KE, Szaflik JP. Bionic eye review – An update. J Clin Neurosci 2020; 78:8-19. [DOI: 10.1016/j.jocn.2020.05.041] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 05/03/2020] [Indexed: 01/26/2023]
|
36
|
Shim S, Eom K, Jeong J, Kim SJ. Retinal Prosthetic Approaches to Enhance Visual Perception for Blind Patients. MICROMACHINES 2020; 11:E535. [PMID: 32456341 PMCID: PMC7281011 DOI: 10.3390/mi11050535] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/22/2020] [Accepted: 05/22/2020] [Indexed: 12/14/2022]
Abstract
Retinal prostheses are implantable devices that aim to restore the vision of blind patients suffering from retinal degeneration, mainly by artificially stimulating the remaining retinal neurons. Some retinal prostheses have successfully reached the stage of clinical trials; however, these devices can only restore vision partially and remain insufficient to enable patients to conduct everyday life independently. The visual acuity of the artificial vision is limited by various factors from both engineering and physiological perspectives. To overcome those issues and further enhance the visual resolution of retinal prostheses, a variety of retinal prosthetic approaches have been proposed, based on optimization of the geometries of electrode arrays and stimulation pulse parameters. Other retinal stimulation modalities such as optics, ultrasound, and magnetics have also been utilized to address the limitations in conventional electrical stimulation. Although none of these approaches have been clinically proven to fully restore the function of a degenerated retina, the extensive efforts made in this field have demonstrated a series of encouraging findings for the next generation of retinal prostheses, and these could potentially enhance the visual acuity of retinal prostheses. In this article, a comprehensive and up-to-date overview of retinal prosthetic strategies is provided, with a specific focus on a quantitative assessment of visual acuity results from various retinal stimulation technologies. The aim is to highlight future directions toward high-resolution retinal prostheses.
Collapse
Affiliation(s)
- Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, College of Information and Biomedical Engineering, Pusan National University, Yangsan 50612, Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea;
- Inter-university Semiconductor Research Center, College of Engineering, Seoul National University, Seoul 08826, Korea
- Institute on Aging, College of Medicine, Seoul National University, Seoul 08826, Korea
| |
Collapse
|
37
|
Chen J, Poulaki V, Kim SJ, Eldred WD, Kane S, Gingerich M, Shire DB, Jensen R, DeWalt G, Kaplan HJ, Rizzo JF. Implantation and Extraction of Penetrating Electrode Arrays in Minipig Retinas. Transl Vis Sci Technol 2020; 9:19. [PMID: 32821491 PMCID: PMC7401973 DOI: 10.1167/tvst.9.5.19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 12/31/2019] [Indexed: 12/12/2022] Open
Abstract
Purpose This work was motivated by the goals of demonstrating methods to fabricate and implant large numbers of penetrating arrays into the retina and the feasibility of extraction. Methods Arrays of inactive, three-dimensional (3D) SU-8 structures were microfabricated onto 13-µm polyimide substrates. Standard vitreoretinal surgical techniques were used with an ab externo approach for subretinal implantation of arrays in 12 mini-pigs. In the first three surgeries, different post-geometries were explored, while a preferred design (128-µm tall, 30-µm diameter, 200-µm spacing) was used for the remaining nine implantations. Two arrays were extracted. Funduscopy, optical coherence tomography (OCT) and immunohistochemistry of the retinae were performed. The unoperated eyes and tissue far from implantation served as controls. A thirteenth pig was implanted with a planar array. Results Ten implant surgeries had no significant complication, and two arrays were successfully extracted. One retinal tear occurred after implantation due to too long posts in an early surgery. In “successful” cases, OCT showed close apposition of the arrays to the retina and integration of the posts, the tops of which were positioned at the junction of the inner plexiform and ganglion cells, without significant gliosis. Conclusions These results provide a proof-of-concept that relatively large numbers of 3D posts can be implanted into, and extracted from, the retina of mini-pigs. Our surgical numbers were relatively small, especially for the extractions, and our conclusions must be viewed with that limitation. Our methods are applicable for human surgeries. Translational Relevance This study provides results of implantation and extraction of relatively large numbers of 3D posts from the retina of minipig eyes. If similar technology were used in humans, a 3D array of this type should lower perceptual thresholds, provide safer long-term stimulation, and perhaps provide better perceptual outcomes.
Collapse
Affiliation(s)
- Jinghua Chen
- Department of Ophthalmology, University of Florida, College of Medicine, Gainesville, FL, USA
| | - Vasiliki Poulaki
- Boston VA Healthcare System, Ophthalmology, Jamaica Plain, Boston, MA, USA
| | - Seong-Joon Kim
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea
| | | | | | | | | | - Ralph Jensen
- Boston VA Healthcare System, Ophthalmology, Jamaica Plain, Boston, MA, USA
| | - Gloria DeWalt
- Department of Biology, Boston University, Boston, MA, USA
| | - Henry J Kaplan
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, KY, USA
| | - Joseph F Rizzo
- Department of Ophthalmology, Harvard Medical School and the Massachusetts Eye and Ear, Boston, MA, USA
| |
Collapse
|
38
|
PRIMA subretinal wireless photovoltaic microchip implantation in non-human primate and feline models. PLoS One 2020; 15:e0230713. [PMID: 32267845 PMCID: PMC7141693 DOI: 10.1371/journal.pone.0230713] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 03/05/2020] [Indexed: 12/05/2022] Open
Abstract
Purpose To evaluate the surgical technique for subretinal implantation of two sizes of PRIMA photovoltaic wireless microchip in two animal models, and refine these surgical procedures for human trials. Methods Cats and Macaca fascicularis primates with healthy retina underwent vitrectomy surgery and were implanted with subretinal wireless photovoltaic microchip at the macula/central retina. The 1.5mm PRIMA chip was initially studied in feline eyes. PRIMA implant (2mm,1.5mm sizes) arrays were studied in primates. Feasibility of subretinal chip implantation was evaluated with a newly-developed surgical technique, with surgical complications and adverse events recorded. Results The 1.5mm implant was placed in the central retina of 11 feline eyes, with implantation duration 43–106 days. The 1.5mm implant was correctly positioned into central macula of 11 primate eyes, with follow-up periods of minimum 6 weeks (n = 11), 2 years (n = 2), and one eye for 3 years. One primate eye underwent multi-chip 1.5mm implantation using two 1.5mm chips. The 2mm implant was delivered to 4 primate eyes. Optical coherence tomography confirmed correct surgical placement of photovoltaic arrays in the subretinal space in all 26 eyes. Intraoperative complications in primate eyes included retinal tear, macular hole, retinal detachment, and vitreous hemorrhage that resolved spontaneously. Postoperatively, there was no case of significant ocular inflammation in the 1.5mm implant group. Conclusions We report subretinal implantation of 1.5mm and 2mm photovoltaic arrays in the central retina of feline and central macula of primate eyes with a low rate of device-related complications. The in vivo PRIMA implantation technique has been developed and refined for use for a 2mm PRIMA implant in ongoing human trials.
Collapse
|
39
|
Kleinlogel S, Vogl C, Jeschke M, Neef J, Moser T. Emerging approaches for restoration of hearing and vision. Physiol Rev 2020; 100:1467-1525. [DOI: 10.1152/physrev.00035.2019] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Impairments of vision and hearing are highly prevalent conditions limiting the quality of life and presenting a major socioeconomic burden. For long, retinal and cochlear disorders have remained intractable for causal therapies, with sensory rehabilitation limited to glasses, hearing aids, and electrical cochlear or retinal implants. Recently, the application of gene therapy and optogenetics to eye and ear has generated hope for a fundamental improvement of vision and hearing restoration. To date, one gene therapy for the restoration of vision has been approved and undergoing clinical trials will broaden its application including gene replacement, genome editing, and regenerative approaches. Moreover, optogenetics, i.e. controlling the activity of cells by light, offers a more general alternative strategy. Over little more than a decade, optogenetic approaches have been developed and applied to better understand the function of biological systems, while protein engineers have identified and designed new opsin variants with desired physiological features. Considering potential clinical applications of optogenetics, the spotlight is on the sensory systems. Multiple efforts have been undertaken to restore lost or hampered function in eye and ear. Optogenetic stimulation promises to overcome fundamental shortcomings of electrical stimulation, namely poor spatial resolution and cellular specificity, and accordingly to deliver more detailed sensory information. This review aims at providing a comprehensive reference on current gene therapeutic and optogenetic research relevant to the restoration of hearing and vision. We will introduce gene-therapeutic approaches and discuss the biotechnological and optoelectronic aspects of optogenetic hearing and vision restoration.
Collapse
Affiliation(s)
| | | | | | | | - Tobias Moser
- Institute for Auditory Neuroscience, University Medical Center Goettingen, Germany
| |
Collapse
|
40
|
Photovoltaic Restoration of Central Vision in Atrophic Age-Related Macular Degeneration. Ophthalmology 2020; 127:1097-1104. [PMID: 32249038 DOI: 10.1016/j.ophtha.2020.02.024] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 02/14/2020] [Accepted: 02/18/2020] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Loss of photoreceptors in atrophic age-related macular degeneration results in severe visual impairment, although some peripheral vision is retained. To restore central vision without compromising the residual peripheral field, we developed a wireless photovoltaic retinal implant (PRIMA; Pixium Vision, Paris, France) in which pixels convert images projected from video glasses using near-infrared light into electric current to stimulate the nearby inner retinal neurons. DESIGN We carried out a first-in-human clinical trial to test the safety and efficacy of the prosthesis in patients with geographic atrophy (ClinicalTrials.gov identifier, NCT03333954). PARTICIPANTS Five patients with geographic atrophy zone of at least 3 optic disc diameters, no foveal light perception, and best-corrected visual acuity of 20/400 to 20/1000 in the worse-seeing study eye. METHODS The 2-mm wide, 30-μm thick chip, containing 378 pixels (each 100 μm in diameter), was implanted subretinally in the area of atrophy (absolute scotoma). MAIN OUTCOME MEASURES Anatomic outcomes were assessed with fundus photography and OCT for up to 12 months of follow-up. Prosthetic vision was assessed by mapping light perception, bar orientation, letter recognition, and Landolt C acuity. RESULTS In all patients, the prosthesis was implanted successfully under the macula, although in 2 patients, it was implanted in unintended locations: within the choroid and off center by 2 mm. All 5 patients could perceive white-yellow prosthetic visual patterns with adjustable brightness in the previous scotomata. The 3 with optimal placement of the implant demonstrated prosthetic acuity of 20/460 to 20/550, and the patient with the off-center implant demonstrated 20/800 acuity. Residual natural acuity did not decrease after implantation in any patient. CONCLUSIONS Implantation of the PRIMA did not decrease the residual natural acuity, and it restored visual sensitivity in the former scotoma in each of the 5 patients. In 3 patients with the proper placement of the chip, prosthetic visual acuity was only 10% to 30% less than the level expected from the pixel pitch (20/420). Therefore, the use of optical or electronic magnification in the glasses as well as smaller pixels in future implants may improve visual acuity even further.
Collapse
|
41
|
Spatiotemporal integration of visual stimuli and its relevance to the use of a divisional power supply scheme for retinal prosthesis. PLoS One 2020; 15:e0228861. [PMID: 32084146 PMCID: PMC7034871 DOI: 10.1371/journal.pone.0228861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 01/25/2020] [Indexed: 11/19/2022] Open
Abstract
A wireless photovoltaic retinal prosthesis is currently being studied with the aim of providing prosthetic vision to patients with retinitis pigmentosa (RP) and age-related macular degeneration (AMD). The major challenge of a photovoltaic device is its limited power efficiency. Our retinal prosthetic design implements a unique divisional power supply scheme (DPSS) system that provides the electrical power generated by all of the solar cells to only a subset of electrodes at any moment in time. The aim of the present study was to systematically characterize the spatiotemporal integration performance of the system under various DPSS conditions using human subjects and a psychophysical approach. A 16x16 pixels LED array controlled by Arduino was used to simulate the output signal of the DPSS design, and human performance under different visual stimulations at various update frequencies was then used to assess the spatiotemporal capability of retinal prostheses. The results showed that the contrast polarity of the image, image brightness, and division number influenced the lower limit of the update frequency of the DPSS system, while, on the other hand, visual angle, ambient light level, and stimulation order did not affect performance significantly. Pattern recognition by visual persistence with spatiotemporal integration of multiple frames of sparse dots is a feasible approach in retinal prosthesis design. These findings provide an insight into how to optimize a photovoltaic retinal prosthesis using a DPSS design with an appropriate update frequency for reliable pattern recognition. This will help the development of a wireless device able to restore vision to RP and AMD patients in the future.
Collapse
|
42
|
Abstract
Developments of new strategies to restore vision and improving on current strategies by harnessing new advancements in material and electrical sciences, and biological and genetic-based technologies are of upmost health priorities around the world. Federal and private entities are spending billions of dollars on visual prosthetics technologies. This review describes the most current and state-of-the-art bioengineering technologies to restore vision. This includes a thorough description of traditional electrode-based visual prosthetics that have improved substantially since early prototypes. Recent advances in molecular and synthetic biology have transformed vision-assisted technologies; For example, optogenetic technologies that introduce light-responsive proteins offer excellent resolution but cortical applications are restricted by fiber implantation and tissue damage. Other stimulation modalities, such as magnetic fields, have been explored to achieve non-invasive neuromodulation. Miniature magnetic coils are currently being developed to activate select groups of neurons. Magnetically-responsive nanoparticles or exogenous proteins can significantly enhance the coupling between external electromagnetic devices and any neurons affiliated with these modifications. The need to minimize cytotoxic effects for nanoparticle-based therapies will likely restrict the number of usable materials. Nevertheless, advances in identifying and utilizing proteins that respond to magnetic fields may lead to non-invasive, cell-specific stimulation and may overcome many of the limitations that currently exist with other methods. Finally, sensory substitution systems also serve as viable visual prostheses by converting visual input to auditory and somatosensory stimuli. This review also discusses major challenges in the field and offers bioengineering strategies to overcome those.
Collapse
Affiliation(s)
- Alexander Farnum
- Department of Biomedical Engineering, College of Engineering, Michigan State University, East Lansing, MI, United States
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, United States
| | - Galit Pelled
- Department of Biomedical Engineering, College of Engineering, Michigan State University, East Lansing, MI, United States
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, United States
- Department of Radiology, College of Human Medicine, Michigan State University, East Lansing, MI, United States
| |
Collapse
|
43
|
Damle S, Liu YH, Arya S, Oesch NW, Lo YH. Vertically integrated photo junction-field-effect transistor pixels for retinal prosthesis. BIOMEDICAL OPTICS EXPRESS 2020; 11:55-67. [PMID: 32010499 PMCID: PMC6968743 DOI: 10.1364/boe.11.000055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 11/20/2019] [Accepted: 11/24/2019] [Indexed: 06/10/2023]
Abstract
Optoelectronic retinal prostheses transduce light into electrical current for neural stimulation. We introduce a novel optoelectronic pixel architecture consisting of a vertically integrated photo junction-field-effect transistor (Photo-JFET) and neural stimulating electrode. Experimental measurements demonstrate that optically addressed Photo-JFET pixels utilize phototransistive gain to produce a broad range of neural stimulation current and can effectively stimulate retinal neurons in vitro. The compact nature of the Photo-JFET pixel can enable high resolution retinal prostheses with the smallest reported optoelectronic pixel size to help restore high visual acuity in patients with degenerative retinal diseases.
Collapse
Affiliation(s)
- Samir Damle
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive La Jolla, CA 92093, USA
| | - Yu-Hsin Liu
- Nanovision Biosciences, Inc., 3366 N. Torrey Pines Court, Suite 220, La Jolla, CA 92037, USA
| | - Shaurya Arya
- Department of Electrical and Computer Engineering, University of California San Diego, Engineer Ln, La Jolla, CA 92161, USA
| | - Nicholas W. Oesch
- Department of Psychology, University of California San Diego, 9500 Gilman Drive, CA 92093, USA
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, 9415 Campus Point Drive San Diego, CA 92093, USA
| | - Yu-Hwa Lo
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California San Diego, 9415 Campus Point Drive San Diego, CA 92093, USA
| |
Collapse
|
44
|
Montazeri L, El Zarif N, Trenholm S, Sawan M. Optogenetic Stimulation for Restoring Vision to Patients Suffering From Retinal Degenerative Diseases: Current Strategies and Future Directions. IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS 2019; 13:1792-1807. [PMID: 31689206 DOI: 10.1109/tbcas.2019.2951298] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Optogenetic strategies for vision restoration involve photosensitizing surviving retinal neurons following retinal degeneration, using emerging optogenetic techniques. This approach opens the door to a minimally-invasive retinal vision restoration approach. Moreover, light stimulation has the potential to offer better spatial and temporal resolution than conventional retinal electrical prosthetics. Although proof-of-concept studies in animal models have demonstrated the possibility of restoring vision using optogenetic techniques, and initial clinical trials are underway, there are still hurdles to pass before such an approach restores naturalistic vision in humans. One limitation is the development of light stimulation devices to activate optogenetic channels in the retina. Here we review recent progress in the design and implementation of optogenetic stimulation devices and outline the corresponding technological challenges. Finally, while most work to date has focused on providing therapy to patients suffering from retinitis pigmentosa, we provide additional insights into strategies for applying optogenetic vision restoration to patients suffering from age-related macular degeneration.
Collapse
|
45
|
Lohmann TK, Haiss F, Schaffrath K, Schnitzler AC, Waschkowski F, Barz C, van der Meer AM, Werner C, Johnen S, Laube T, Bornfeld N, Mazinani BE, Rößler G, Mokwa W, Walter P. The very large electrode array for retinal stimulation (VLARS)—A concept study. J Neural Eng 2019; 16:066031. [DOI: 10.1088/1741-2552/ab4113] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
46
|
Seo HW, Kim N, Ahn J, Cha S, Goo YS, Kim S. A 3D flexible microelectrode array for subretinal stimulation. J Neural Eng 2019; 16:056016. [PMID: 31357188 DOI: 10.1088/1741-2552/ab36ab] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Various retinal prostheses have been developed to restore the vision for blind patients, and some of them are already in clinical use. In this paper, we present a three-dimensional (3D) microelectrode array for a subretinal device that can effectively stimulate retinal cells. APPROACH To investigate the effect of electrode designs on the electric field distribution, we simulated various electrode shapes and sizes using finite element analysis. Based on the simulation results, the 3D microelectrode array was fabricated and evaluated in in vitro condition. MAIN RESULTS Through the simulation, we verified that an electrode design of square frustum was effective to stimulate with high contrast. Also, the 3D flexible and transparent microelectrode array based on silicon and polydimethylsiloxane was fabricated using micro-electro-mechanical system technologies. In in vitro experiments, the subretinally positioned 3D microelectrodes properly evoked spikes in retinal ganglion cells. The mean threshold current was 7.4 µA and the threshold charge density was 33.64 µC·cm-2 per phase. SIGNIFICANCE The results demonstrate the feasibility of the fabricated 3D microelectrodes as the subretinal prosthesis. The developed microelectrode array would be integrated with the stimulation circuitry and implanted in animals for further in vivo experiments.
Collapse
Affiliation(s)
- Hee Won Seo
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, Republic of Korea
| | | | | | | | | | | |
Collapse
|
47
|
Flores T, Huang T, Bhuckory M, Ho E, Chen Z, Dalal R, Galambos L, Kamins T, Mathieson K, Palanker D. Honeycomb-shaped electro-neural interface enables cellular-scale pixels in subretinal prosthesis. Sci Rep 2019; 9:10657. [PMID: 31337815 PMCID: PMC6650428 DOI: 10.1038/s41598-019-47082-y] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 07/10/2019] [Indexed: 11/08/2022] Open
Abstract
High-resolution visual prostheses require small, densely packed pixels, but limited penetration depth of the electric field formed by a planar electrode array constrains such miniaturization. We present a novel honeycomb configuration of an electrode array with vertically separated active and return electrodes designed to leverage migration of retinal cells into voids in the subretinal space. Insulating walls surrounding each pixel decouple the field penetration depth from the pixel width by aligning the electric field vertically, enabling a decrease of the pixel size down to cellular dimensions. We demonstrate that inner retinal cells migrate into the 25 μm deep honeycomb wells as narrow as 18 μm, resulting in more than half of these cells residing within the electrode cavities. Immune response to honeycombs is comparable to that with planar arrays. Modeled stimulation threshold current density with honeycombs does not increase substantially with reduced pixel size, unlike quadratic increase with planar arrays. This 3-D electrode configuration may enable functional restoration of central vision with acuity better than 20/100 for millions of patients suffering from age-related macular degeneration.
Collapse
Affiliation(s)
- Thomas Flores
- Department of Applied Physics, Stanford University, Stanford, CA, USA.
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA.
| | - Tiffany Huang
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Mohajeet Bhuckory
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Elton Ho
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Physics, Stanford University, Stanford, CA, USA
| | - Zhijie Chen
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Roopa Dalal
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| | - Ludwig Galambos
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Theodore Kamins
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA, USA
| | - Keith Mathieson
- Institute of Photonics, University of Strathclyde, Glasgow, Scotland, UK
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University, Stanford, CA, USA
| |
Collapse
|
48
|
Zeng Q, Zhao S, Yang H, Zhang Y, Wu T. Micro/Nano Technologies for High-Density Retinal Implant. MICROMACHINES 2019; 10:E419. [PMID: 31234507 PMCID: PMC6630275 DOI: 10.3390/mi10060419] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 01/10/2023]
Abstract
During the past decades, there have been leaps in the development of micro/nano retinal implant technologies, which is one of the emerging applications in neural interfaces to restore vision. However, higher feedthroughs within a limited space are needed for more complex electronic systems and precise neural modulations. Active implantable medical electronics are required to have good electrical and mechanical properties, such as being small, light, and biocompatible, and with low power consumption and minimal immunological reactions during long-term implantation. For this purpose, high-density implantable packaging and flexible microelectrode arrays (fMEAs) as well as high-performance coating materials for retinal stimulation are crucial to achieve high resolution. In this review, we mainly focus on the considerations of the high-feedthrough encapsulation of implantable biomedical components to prolong working life, and fMEAs for different implant sites to deliver electrical stimulation to targeted retinal neuron cells. In addition, the functional electrode materials to achieve superior stimulation efficiency are also reviewed. The existing challenge and future research directions of micro/nano technologies for retinal implant are briefly discussed at the end of the review.
Collapse
Affiliation(s)
- Qi Zeng
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| | - Saisai Zhao
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| | - Hangao Yang
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| | - Yi Zhang
- Shenzhen CAS-Envision Medical Technology Co. Ltd., Shenzhen 518100, China.
| | - Tianzhun Wu
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| |
Collapse
|
49
|
Bosse B, Damle S, Akinin A, Jing Y, Bartsch DU, Cheng L, Oesch N, Lo YH, Cauwenberghs G, Freeman WR. In Vivo Photovoltaic Performance of a Silicon Nanowire Photodiode-Based Retinal Prosthesis. Invest Ophthalmol Vis Sci 2019; 59:5885-5892. [PMID: 30550611 PMCID: PMC6295940 DOI: 10.1167/iovs.18-24554] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Purpose For more than 20 years, there has been an international, multidisciplinary effort to develop retinal prostheses to restore functional vision to patients blinded by retinal degeneration. We developed a novel subretinal prosthesis with 1512 optically addressed silicon nanowire photodiodes, which transduce incident light into an electrical stimulation of the remaining retinal circuitry. This study was conducted to evaluate the efficacy of optically driving the subretinal prosthesis to produce visual cortex activation via electrical stimulation of the retina. Methods We measured electrically evoked potential responses (EEPs) in rabbit visual cortex in response to illumination of the subretinal nanowire prosthesis with pulsed 852-nm infrared (IR) light. We compared the EEP responses to visually evoked potential responses (VEPs) to pulsed 532-nm visible light (positive control) and pulsed 852-nm IR light (negative control). Results Activating the devices with IR light produced EEP responses with a significantly higher trough-to-peak amplitude (54.17 ± 33.4 μV) than IR light alone (24.07 ± 22.1 μV) or background cortical activity (23.22 ± 17.2 μV). EEP latencies were significantly faster than focal VEP latencies. Focal VEPs produced significantly higher amplitudes (94.88 ± 43.3 μV) than EEPs. We also demonstrated how an electrode placed on the cornea can be used as a noninvasive method to monitor the function of the implant. Conclusions These results show that subretinal electrical stimulation with nanowire electrodes can elicit EEPs in the visual cortex, providing evidence for the viability of a subretinal nanowire prosthetic approach for vision restoration.
Collapse
Affiliation(s)
- Brandon Bosse
- Nanovision Biosciences, Inc., La Jolla, California, United States
| | - Samir Damle
- Department of Bioengineering, University of California, San Diego, California, United States
| | - Abraham Akinin
- Department of Bioengineering, University of California, San Diego, California, United States
| | - Yi Jing
- Nanovision Biosciences, Inc., La Jolla, California, United States
| | - Dirk-Uwe Bartsch
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California, San Diego, California, United States
| | - Lingyun Cheng
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California, San Diego, California, United States
| | - Nicholas Oesch
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California, San Diego, California, United States.,Department of Psychology, University of California, San Diego, California, United States
| | - Yu-Hwa Lo
- Department of Electrical and Computer Engineering, University of California, San Diego, California, United States
| | - Gert Cauwenberghs
- Department of Bioengineering, University of California, San Diego, California, United States
| | - William R Freeman
- Jacobs Retina Center at Shiley Eye Institute, Department of Ophthalmology, University of California, San Diego, California, United States
| |
Collapse
|
50
|
Guo T, Tsai D, Yang CY, Al Abed A, Twyford P, Fried SI, Morley JW, Suaning GJ, Dokos S, Lovell NH. Mediating Retinal Ganglion Cell Spike Rates Using High-Frequency Electrical Stimulation. Front Neurosci 2019; 13:413. [PMID: 31114476 PMCID: PMC6503046 DOI: 10.3389/fnins.2019.00413] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/11/2019] [Indexed: 12/30/2022] Open
Abstract
Recent retinal studies have directed more attention to sophisticated stimulation strategies based on high-frequency (>1.0 kHz) electrical stimulation (HFS). In these studies, each retinal ganglion cell (RGC) type demonstrated a characteristic stimulus-strength-dependent response to HFS, offering the intriguing possibility of focally targeting retinal neurons to provide useful visual information by retinal prosthetics. Ionic mechanisms are known to affect the responses of electrogenic cells during electrical stimulation. However, how these mechanisms affect RGC responses is not well understood at present, particularly when applying HFS. Here, we investigate this issue via an in silico model of the RGC. We calibrate and validate the model using an in vitro retinal preparation. An RGC model based on accurate biophysics and realistic representation of cell morphology, was used to investigate how RGCs respond to HFS. The model was able to closely replicate the stimulus-strength-dependent suppression of RGC action potentials observed experimentally. Our results suggest that spike inhibition during HFS is due to local membrane hyperpolarization caused by outward membrane currents near the stimulus electrode. In addition, the extent of HFS-induced inhibition can be largely altered by the intrinsic properties of the inward sodium current. Finally, stimulus-strength-dependent suppression can be modulated by a wide range of stimulation frequencies, under generalized electrode placement conditions. In vitro experiments verified the computational modeling data. This modeling and experimental approach can be extended to further our understanding on the effects of novel stimulus strategies by simulating RGC stimulus-response profiles over a wider range of stimulation frequencies and electrode locations than have previously been explored.
Collapse
Affiliation(s)
- Tianruo Guo
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - David Tsai
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia.,Department of Biological Sciences, Columbia University, New York, NY, United States.,Department of Electrical Engineering, Columbia University, New York, NY, United States
| | - Chih Yu Yang
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - Amr Al Abed
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - Perry Twyford
- VA Boston Healthcare System, Boston, MA, United States
| | - Shelley I Fried
- VA Boston Healthcare System, Boston, MA, United States.,Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, MA, United States
| | - John W Morley
- School of Medicine, Western Sydney University, Penrith, NSW, Australia
| | - Gregg J Suaning
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia.,School of Biomedical Engineering, The University of Sydney, Sydney, NSW, Australia
| | - Socrates Dokos
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| |
Collapse
|