1
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Amaral L, Thomas P, Amedi A, Striem-Amit E. Longitudinal stability of individual brain plasticity patterns in blindness. Proc Natl Acad Sci U S A 2024; 121:e2320251121. [PMID: 39078671 PMCID: PMC11317565 DOI: 10.1073/pnas.2320251121] [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: 11/17/2023] [Accepted: 05/24/2024] [Indexed: 07/31/2024] Open
Abstract
The primary visual cortex (V1) in blindness is engaged in a wide spectrum of tasks and sensory modalities, including audition, touch, language, and memory. This widespread involvement raises questions regarding the constancy of its role and whether it might exhibit flexibility in its function over time, connecting to diverse network functions specific to task demands. This would suggest that reorganized V1 assumes a role like multiple-demand system regions. Alternatively, varying patterns of plasticity in blind V1 may be attributed to individual factors, with different blind individuals recruiting V1 preferentially for different functions. In support of this, we recently showed that V1 functional connectivity (FC) varies greatly across blind individuals. But do these represent stable individual patterns of plasticity, or are they driven more by instantaneous changes, like a multiple-demand system now inhabiting V1? Here, we tested whether individual FC patterns from the V1 of blind individuals are stable over time. We show that over two years, FC from the V1 is unique and highly stable in a small sample of repeatedly sampled congenitally blind individuals. Further, using multivoxel pattern analysis, we demonstrate that the unique reorganization patterns of these individuals allow decoding of participant identity. Together with recent evidence for substantial individual differences in V1 connectivity, this indicates that there may be a consistent role for V1 in blindness, which may differ for each individual. Further, it suggests that the variability in visual reorganization in blindness across individuals could be used to seek stable neuromarkers for sight rehabilitation and assistive approaches.
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Affiliation(s)
- Lénia Amaral
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC20057
| | - Peyton Thomas
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC20057
| | - Amir Amedi
- Ivcher School of Psychology, The Institute for Brain, Mind and Technology, Reichman University, Herzliya4610101, Israel
- The Ruth & Meir Rosenthal Brain Imaging Center, Reichman University, Herzliya4610101, Israel
| | - Ella Striem-Amit
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC20057
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2
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Castro D, Grayden DB, Meffin H, Spencer M. Neural activity shaping in visual prostheses with deep learning. J Neural Eng 2024; 21:046025. [PMID: 38986450 DOI: 10.1088/1741-2552/ad6186] [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: 04/03/2024] [Accepted: 07/10/2024] [Indexed: 07/12/2024]
Abstract
Objective.The visual perception provided by retinal prostheses is limited by the overlapping current spread of adjacent electrodes. This reduces the spatial resolution attainable with unipolar stimulation. Conversely, simultaneous multipolar stimulation guided by the measured neural responses-neural activity shaping (NAS)-can attenuate excessive spread of excitation allowing for more precise control over the pattern of neural activation. However, defining effective multipolar stimulus patterns is a challenging task. Previous attempts focused on analytical solutions based on an assumed linear nonlinear model of retinal response; an analytical model inversion (AMI) approach. Here, we propose a model-free solution for NAS, using artificial neural networks (ANNs) that could be trained with data acquired from the implant.Approach.Our method consists of two ANNs trained sequentially. The measurement predictor network (MPN) is trained on data from the implant and is used to predict how the retina responds to multipolar stimulation. The stimulus generator network is trained on a large dataset of natural images and uses the trained MPN to determine efficient multipolar stimulus patterns by learning its inverse model. We validate our methodin silicousing a realistic model of retinal response to multipolar stimulation.Main results.We show that our ANN-based NAS approach produces sharper retinal activations than the conventional unipolar stimulation strategy. As a theoretical bench-mark of optimal NAS results, we implemented AMI stimulation by inverting the model used to simulate the retina. Our ANN strategy produced equivalent results to AMI, while not being restricted to any specific type of retina model and being three orders of magnitude more computationally efficient.Significance.Our novel protocol provides a method for efficient and personalized retinal stimulation, which may improve the visual experience and quality of life of retinal prosthesis users.
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Affiliation(s)
- Domingos Castro
- Neuroengineering and Computational Neuroscience Lab, i3S-Institute for Research and Innovation in Health, University of Porto, Porto, Portugal
- Faculty of Engineering of the University of Porto, Porto, Portugal
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
- Graeme 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
- Graeme Clark Institute of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Martin Spencer
- Department of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
- Graeme Clark Institute of Biomedical Engineering, The University of Melbourne, Parkville, Victoria, Australia
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3
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Holiel HA, Fawzi SA, Al-Atabany W. Pre-processing visual scenes for retinal prosthesis systems: A comprehensive review. Artif Organs 2024. [PMID: 39023279 DOI: 10.1111/aor.14824] [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: 10/31/2023] [Revised: 05/13/2024] [Accepted: 06/21/2024] [Indexed: 07/20/2024]
Abstract
BACKGROUND Retinal prostheses offer hope for individuals with degenerative retinal diseases by stimulating the remaining retinal cells to partially restore their vision. This review delves into the current advancements in retinal prosthesis technology, with a special emphasis on the pivotal role that image processing and machine learning techniques play in this evolution. METHODS We provide a comprehensive analysis of the existing implantable devices and optogenetic strategies, delineating their advantages, limitations, and challenges in addressing complex visual tasks. The review extends to various image processing algorithms and deep learning architectures that have been implemented to enhance the functionality of retinal prosthetic devices. We also illustrate the testing results by demonstrating the clinical trials or using Simulated Prosthetic Vision (SPV) through phosphene simulations, which is a critical aspect of simulating visual perception for retinal prosthesis users. RESULTS Our review highlights the significant progress in retinal prosthesis technology, particularly its capacity to augment visual perception among the visually impaired. It discusses the integration between image processing and deep learning, illustrating their impact on individual interactions and navigations within the environment through applying clinical trials and also illustrating the limitations of some techniques to be used with current devices, as some approaches only use simulation even on sighted-normal individuals or rely on qualitative analysis, where some consider realistic perception models and others do not. CONCLUSION This interdisciplinary field holds promise for the future of retinal prostheses, with the potential to significantly enhance the quality of life for individuals with retinal prostheses. Future research directions should pivot towards optimizing phosphene simulations for SPV approaches, considering the distorted and confusing nature of phosphene perception, thereby enriching the visual perception provided by these prosthetic devices. This endeavor will not only improve navigational independence but also facilitate a more immersive interaction with the environment.
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Affiliation(s)
- Heidi Ahmed Holiel
- Medical Imaging and Image Processing Research Group, Center for Informatics Science, Nile University, Sheikh Zayed City, Egypt
| | - Sahar Ali Fawzi
- Medical Imaging and Image Processing Research Group, Center for Informatics Science, Nile University, Sheikh Zayed City, Egypt
- Systems and Biomedical Engineering Department, Cairo University, Giza, Egypt
| | - Walid Al-Atabany
- Medical Imaging and Image Processing Research Group, Center for Informatics Science, Nile University, Sheikh Zayed City, Egypt
- Biomedical Engineering Department, Helwan University, Helwan, Egypt
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4
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Jeong H, Lee T, Kim J, Jeong HS, Jun SB, Seo JM. Fabrication and validation of flexible neural electrodes based on polyimide tape and gold sheet. Biomed Eng Lett 2024; 14:267-278. [PMID: 38374899 PMCID: PMC10874365 DOI: 10.1007/s13534-023-00345-0] [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: 01/27/2023] [Revised: 10/19/2023] [Accepted: 11/12/2023] [Indexed: 02/21/2024] Open
Abstract
This research was conducted to apply polyimide tape, which has the advantages of low price ans strong adhesive strength, to the neural electrode process. In addition, to maximize the low-cost characteristics, a fabrication process based on UV laser patterning rather than a photolithography process was introduced. The fabrication process started by attaching the gold sheet on the conductive double-sided tape without being torn or crushed. Then, the gold sheet and the double-sided tape were patterned together using UV laser. The patterned layer was transferred to the single-side polyimide tape. For insulation layer, electrode site opened single-sided polyimide tape was prepared. Polydimethylsiloxane was used as an adhesion layer, and alignment between electrode sites and opening sites was processed manually. The minimum line width achieved through the proposed fabrication process was approximately 100 μ m, and the sheet resistance of the conductive layer was 0.635 Ω /sq. Measured cathodal charge storage capacity was 0.72 mC/cm2 and impedance at 1 kHz was 4.07 kΩ /cm2. Validation of fabricated electrode was confirmed by conducting 30 days accelerated soak test, flexibility test, adhesion test and ex vivo stimulation test. The novel flexible neural electrodes based on single-sided polyimide tape and UV laser patterned gold sheet was fabricated successfully. Conventional neural electrode fabrication processes based on polyimide substrate has a disadvantages such as long fabrication time, expensive costs, and probability of delamination between layers. However, the novel fabrication process which we introduced can overcome many shortcomings of existing processes, and offers great advantages such as simplicity of fabrication, inexpensiveness, flexibility and long-term reliability.
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Affiliation(s)
- Hyunbeen Jeong
- Electrical and Computer Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Inter-university Semiconductor Research Center (ISRC), Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Institute of Engineering Research at Seoul National University, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
| | - Taekyung Lee
- Electrical and Computer Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Inter-university Semiconductor Research Center (ISRC), Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Institute of Engineering Research at Seoul National University, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
| | - Jisung Kim
- Electrical and Computer Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Inter-university Semiconductor Research Center (ISRC), Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Institute of Engineering Research at Seoul National University, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
| | - Hee Soo Jeong
- Graduate Program in Smart Factory, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760 Republic of Korea
- Department of Electronic and Electrical Engineering, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760 Republic of Korea
| | - Sang Beom Jun
- Graduate Program in Smart Factory, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760 Republic of Korea
- Department of Electronic and Electrical Engineering, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760 Republic of Korea
- Department of Brain and Cognitive Sciences, Ewha Womans University, 52, Ewhayeodae-gil, Seodaemun-gu, Seoul, 03760 Republic of Korea
| | - Jong-Mo Seo
- Electrical and Computer Engineering, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Inter-university Semiconductor Research Center (ISRC), Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Institute of Engineering Research at Seoul National University, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul, 08826 Republic of Korea
- Biomedical Research Institute, Seoul National University Hospital, 101, Daehak-ro, Jongno-gu, Seoul, 03080 Republic of Korea
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Amaral L, Thomas P, Amedi A, Striem-Amit E. Longitudinal stability of individual brain plasticity patterns in blindness. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.01.565196. [PMID: 37986779 PMCID: PMC10659359 DOI: 10.1101/2023.11.01.565196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The primary visual cortex (V1) in individuals born blind is engaged in a wide spectrum of tasks and sensory modalities, including audition, touch, language, and memory. This widespread involvement raises questions regarding the constancy of its role and whether it might exhibit flexibility in its function over time, connecting to diverse network functions in response to task-specific demands. This would suggest that reorganized V1 takes on a role similar to cognitive multiple-demand system regions. Alternatively, it is possible that the varying patterns of plasticity observed in the blind V1 can be attributed to individual factors, whereby different blind individuals recruit V1 for different functions, highlighting the immense idiosyncrasy of plasticity. In support of this second account, we have recently shown that V1 functional connectivity varies greatly across blind individuals. But do these represent stable individual patterns of plasticity or merely instantaneous changes, for a multiple-demand system now inhabiting V1? Here we tested if individual connectivity patterns from the visual cortex of blind individuals are stable over time. We show that over two years, fMRI functional connectivity from the primary visual cortex is unique and highly stable in a small sample of repeatedly sampled congenitally blind individuals. Further, using multivoxel pattern analysis, we demonstrate that the unique reorganization patterns of these individuals allow decoding of participant identity. Together with recent evidence for substantial individual differences in visual cortex connectivity, this indicates there may be a consistent role for the visual cortex in blindness, which may differ for each individual. Further, it suggests that the variability in visual reorganization in blindness across individuals could be used to seek stable neuromarkers for sight rehabilitation and assistive approaches.
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Affiliation(s)
- Lénia Amaral
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Peyton Thomas
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Amir Amedi
- Ivcher School of Psychology, The Institute for Brain, Mind and Technology, Reichman University, Herzliya, Israel
- The Ruth & Meir Rosenthal Brain Imaging Center, Reichman University, Herzliya, Israel
| | - Ella Striem-Amit
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC 20057, USA
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6
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Kasowski J, Johnson BA, Neydavood R, Akkaraju A, Beyeler M. A systematic review of extended reality (XR) for understanding and augmenting vision loss. J Vis 2023; 23:5. [PMID: 37140911 PMCID: PMC10166121 DOI: 10.1167/jov.23.5.5] [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: 11/14/2022] [Accepted: 04/04/2023] [Indexed: 05/05/2023] Open
Abstract
Over the past decade, extended reality (XR) has emerged as an assistive technology not only to augment residual vision of people losing their sight but also to study the rudimentary vision restored to blind people by a visual neuroprosthesis. A defining quality of these XR technologies is their ability to update the stimulus based on the user's eye, head, or body movements. To make the best use of these emerging technologies, it is valuable and timely to understand the state of this research and identify any shortcomings that are present. Here we present a systematic literature review of 227 publications from 106 different venues assessing the potential of XR technology to further visual accessibility. In contrast to other reviews, we sample studies from multiple scientific disciplines, focus on technology that augments a person's residual vision, and require studies to feature a quantitative evaluation with appropriate end users. We summarize prominent findings from different XR research areas, show how the landscape has changed over the past decade, and identify scientific gaps in the literature. Specifically, we highlight the need for real-world validation, the broadening of end-user participation, and a more nuanced understanding of the usability of different XR-based accessibility aids.
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Affiliation(s)
- Justin Kasowski
- Graduate Program in Dynamical Neuroscience, University of California, Santa Barbara, CA, USA
| | - Byron A Johnson
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Ryan Neydavood
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Anvitha Akkaraju
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
| | - Michael Beyeler
- Department of Psychological & Brain Sciences, University of California, Santa Barbara, CA, USA
- Department of Computer Science, University of California, Santa Barbara, CA, USA
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7
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Sung K, Jo S, Lee J, Park JH, Park YH, Moon J, Kim SJ, Jeong J, Lee J, Eom K. Computational analysis of multichannel magnetothermal neural stimulation using magnetic resonator array. Biomed Eng Lett 2023; 13:209-219. [PMID: 37124115 PMCID: PMC10130299 DOI: 10.1007/s13534-023-00267-x] [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: 09/29/2022] [Revised: 01/24/2023] [Accepted: 02/01/2023] [Indexed: 02/12/2023] Open
Abstract
Heating nanoparticles with a magnetic field could facilitate selective remote control of neural activity in deep tissue. However, current magnetothermal stimulation approaches are limited to single-channel stimulation. Here, we investigated various designs for multichannel magnetothermal stimulation based on an array of resonant coils that are driven by a single loop coil. Using a tuning capacitor that allows resonant coils to resonate at the operating frequency, each coil's ON and OFF resonance can be controlled, enabling us to select stimulation channels. We found that smaller inner diameters of resonant coils produce more localized magnetic fields while larger coils produce magnetic fields over a longer distance. The constructed multichannel resonant coil arrays can provide a high enough magnetic field intensity to raise the temperature of nanoparticles by 8 °C when we apply 35.2 W into the loop coil that is spaced 1 mm from the target neurons. This multichannel stimulation using a simple resonant circuit approach would be useful for clinical applications of magnetothermal neural stimulation.
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Affiliation(s)
- Kyungmo Sung
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Seonghoon Jo
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Jaewook Lee
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Jeong Hoan Park
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117583 Singapore
| | - Young Hoon Park
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Jeongjoo Moon
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
| | - Sung June Kim
- School of Electrical and Computer Engineering, Seoul National University, Seoul, 08826 Republic of Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, Pusan National University, Yangsan, 50612 Republic of Korea
| | - Jonghwan Lee
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI 02912 USA
- Carney Institute for Brain Science, Brown University, Providence, RI 02912 USA
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan, 46241 Republic of Korea
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8
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Zhou M, Young BK, Valle ED, Koo B, Kim J, Weiland JD. Full-field, conformal epiretinal electrode array using hydrogel and polymer hybrid technology. Sci Rep 2023; 13:6973. [PMID: 37117214 PMCID: PMC10147691 DOI: 10.1038/s41598-023-32976-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 04/05/2023] [Indexed: 04/30/2023] Open
Abstract
Shape-morphable electrode arrays can form 3D surfaces to conform to complex neural anatomy and provide consistent positioning needed for next-generation neural interfaces. Retinal prostheses need a curved interface to match the spherical eye and a coverage of several cm to restore peripheral vision. We fabricated a full-field array that can (1) cover a visual field of 57° based on electrode position and of 113° based on the substrate size; (2) fold to form a compact shape for implantation; (3) self-deploy into a curvature fitting the eye after implantation. The full-field array consists of multiple polymer layers, specifically, a sandwich structure of elastomer/polyimide-based-electrode/elastomer, coated on one side with hydrogel. Electrodeposition of high-surface-area platinum/iridium alloy significantly improved the electrical properties of the electrodes. Hydrogel over-coating reduced electrode performance, but the electrodes retained better properties than those without platinum/iridium. The full-field array was rolled into a compact shape and, once implanted into ex vivo pig eyes, restored to a 3D curved surface. The full-field retinal array provides significant coverage of the retina while allowing surgical implantation through an incision 33% of the final device diameter. The shape-changing material platform can be used with other neural interfaces that require conformability to complex neuroanatomy.
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Affiliation(s)
- Muru Zhou
- Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, 48105, USA
| | - Benjamin K Young
- Department of Ophthalmology, Oregon Health and Sciences University, Portland, OR, 97239, USA
| | - Elena Della Valle
- Biomedical Engineering, University of Michigan, Ann Arbor, 48105, USA
| | - Beomseo Koo
- Biomedical Engineering, University of Michigan, Ann Arbor, 48105, USA
| | - Jinsang Kim
- Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, 48105, USA
- Biomedical Engineering, University of Michigan, Ann Arbor, 48105, USA
- Chemical Engineering, University of Michigan, Ann Arbor, 48105, USA
- Materials Science and Engineering, University of Michigan, Ann Arbor, 48105, USA
- Chemistry, University of Michigan, Ann Arbor, 48105, USA
- Biointerfaces Institute, University of Michigan, Ann Arbor, 48105, USA
| | - James D Weiland
- Biomedical Engineering, University of Michigan, Ann Arbor, 48105, USA.
- Biointerfaces Institute, University of Michigan, Ann Arbor, 48105, USA.
- Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, 48105, USA.
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9
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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.
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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
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10
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Yahya Alkhalaf H, Yazed Ahmad M, Ramiah H. Self-Sustainable Biomedical Devices Powered by RF Energy: A Review. SENSORS (BASEL, SWITZERLAND) 2022; 22:6371. [PMID: 36080825 PMCID: PMC9459858 DOI: 10.3390/s22176371] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023]
Abstract
Wearable and implantable medical devices (IMDs) have come a long way in the past few decades and have contributed to the development of many personalized health monitoring and therapeutic applications. Sustaining these devices with reliable and long-term power supply is still an ongoing challenge. This review discusses the challenges and milestones in energizing wearable and IMDs using the RF energy harvesting (RFEH) technique. The review highlights the main integrating frontend blocks such as the wearable and implantable antenna design, matching network, and rectifier topologies. The advantages and bottlenecks of adopting RFEH technology in wearable and IMDs are reviewed, along with the system elements and characteristics that enable these devices to operate in an optimized manner. The applications of RFEH in wearable and IMDs medical devices are elaborated in the final section of this review. This article summarizes the recent developments in RFEH, highlights the gaps, and explores future research opportunities.
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Affiliation(s)
| | - Mohd Yazed Ahmad
- Department of Biomedical Engineering, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Harikrishnan Ramiah
- Department of Electrical Engineering, Universiti Malaya, Kuala Lumpur 50603, Malaysia
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11
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Li W, Haji Ghaffari D, Misra R, Weiland JD. Retinal ganglion cell desensitization is mitigated by varying parameter constant excitation pulse trains. Front Cell Neurosci 2022; 16:897146. [PMID: 36035262 PMCID: PMC9407683 DOI: 10.3389/fncel.2022.897146] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 07/15/2022] [Indexed: 11/20/2022] Open
Abstract
Retinal prostheses partially restore vision in patients blinded by retinitis pigmentosa (RP) and age-related macular degeneration (AMD). One issue that limits the effectiveness of retinal stimulation is the desensitization of the retina response to repeated pulses. Rapid fading of percepts is reported in clinical studies. We studied the retinal output evoked by fixed pulse trains vs. pulse trains that have variable parameters pulse-to-pulse. We used the current clamp to record RGC spiking in the isolated mouse retina. Trains of biphasic current pulses at different frequencies and amplitudes were applied. The main results we report are: (1) RGC desensitization was induced by increasing stimulus frequency, but was unrelated to stimulus amplitude. Desensitization persisted when the 20 Hz stimulation pulses were applied to the retinal ganglion cells at 65 μA, 85 μA, and 105 μA. Subsequent pulses in the train evoked fewer spikes. There was no obvious desensitization when 2 Hz stimulation pulse trains were applied. (2) Blocking inhibitory GABAA receptor increased spontaneous activity but did not reduce desensitization. (3) Pulse trains with constant charge or excitation (based on strength-duration curves) but varying pulse width, amplitude, and shape increased the number of evoked spikes/pulse throughout the pulse train. This suggests that retinal desensitization can be partially overcome by introducing variability into each pulse.
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Affiliation(s)
- Wennan Li
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Dorsa Haji Ghaffari
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - Rohit Misra
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
| | - James D. Weiland
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States
- *Correspondence: James D. Weiland
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Kim J, Seo C, Seo JM. The Design and Analysing Heating Effect of Spiral Planar Coil in COMSOL Multiphysics for Implantable Artificial Retina. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2022; 2022:4261-4264. [PMID: 36085928 DOI: 10.1109/embc48229.2022.9871192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In this paper, simulation data and heat generation due to electromagnetic from spiral planar pair of coils for arti-ficial retinal implant were analyzed by COMSOL Multiphysics. Planar spiral outer and inner coils for an implantable artificial retina were designed and analyzed. The whole geometry was designed in a transplant situation. The parameters of the coil were set within the design limits due to the limitations of im-plant space. The inductance for the coil and the thermal change due to the electromagnetic force generated in the inductively coupled coil were calculated. Analysis of heat transfer in a biological model showed that the maximum heat did not exceed the internal tissue damage temperature. The results showed that a pair of coils designed for artificial retinas can be implanted in vivo without destruction of body tissues.
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Rustogi P, Judy JW. Microgaskets for High-Channel-Density Reconnectable Implantable Packaging. JOURNAL OF MICROELECTROMECHANICAL SYSTEMS : A JOINT IEEE AND ASME PUBLICATION ON MICROSTRUCTURES, MICROACTUATORS, MICROSENSORS, AND MICROSYSTEMS 2022; 31:384-392. [PMID: 35663544 PMCID: PMC9162095 DOI: 10.1109/jmems.2022.3159487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Demands for implantable bioelectronic devices to increase the number of channels for greater functional capacity and resolution, shrink implant size to minimize tissue response and patient burden, and support battery changes and electronics upgrades for long-term operational viability, cannot be met with existing implant-connector technology. In this paper we describe our novel approach to develop a rematable high-channel-density implant-connector technology, with a focus on the design, fabrication, and characterization of its microgasket. The microgaskets made of polydimethylsiloxane elastomer (PDMSe) have achieved much better electrical isolation for neural stimulation (~5 MΩ at 10 kHz) compared with conventional implant connectors (50 kΩ at 10 kHz), despite a 200-fold increase in channel density (conventional: ~0.0644 ch/mm2, microgasket: ~12.8 ch/mm2). The microgaskets also achieved high electrical isolation for neural recording (i.e., ~35 MΩ at 1 kHz) at the same high channel density. When mechanically compressed the microscale vias in the PDMSe microgaskets deform laterally, which could damage or enhance gasket-traversing conductive spring elements in each microscale via depending on their design. We have demonstrated that by lowering the height-to-width aspect ratio of the gasket vias, they can maintain their shape under clamping pressures high enough to achieve high isolation.
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Affiliation(s)
- Paritosh Rustogi
- Electrical and Computer Engineering Department and the Nanoscience Institute for Medical and Engineering Technology, University of Florida, Gainesville, FL 32611 USA
| | - Jack W Judy
- Electrical and Computer Engineering Department, Biomedical Engineering Department, Department of Neurology, and the Nanoscience Institute for Medical and Engineering Technology, University of Florida, Gainesville, FL 32611 USA
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14
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Yang JW, Chen CY, Yu ZY, Chung JH, Liu X, Wu CY, Chen GY. An electroactive hybrid biointerface for enhancing neuronal differentiation and axonal outgrowth on bio-subretinal chip. Mater Today Bio 2022; 14:100253. [PMID: 35464741 PMCID: PMC9018446 DOI: 10.1016/j.mtbio.2022.100253] [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: 01/10/2022] [Revised: 03/14/2022] [Accepted: 03/31/2022] [Indexed: 12/20/2022] Open
Abstract
Retinal prostheses offer viable vision restoration therapy for patients with blindness. However, a critical requirement for maintaining the stable performance of electrical stimulation and signal transmission is the biocompatibility of the electrode interface. Here, we demonstrated a functionalized electrode-neuron biointerface composed of an annealed graphene oxide-collagen (aGO-COL) composite and neuronal cells. The aGO-COL exhibited an electroactive 3D crumpled surface structure and enhanced the differentiation efficiency of PC-12 cells. It is integrated into a photovoltaic self-powered retinal chip to develop a biohybrid retinal implant that facilitates biocompatibility and tissue regeneration. Moreover, aGO-COL micropatterns fabricated via 3D bioprinting can be used to create neuronal cell microarrays, which supports the possibility of retaining the high spatial resolution achieved through electrical stimulation of the retinal chip. This study paves the way for the next generation of biohybrid retinal implants based on biointerfaces.
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Affiliation(s)
- Jia-Wei Yang
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
- Department of Electronics and Electrical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
| | - Chong-You Chen
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
- Department of Electronics and Electrical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
| | - Zih-Yu Yu
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
| | - Johnson H.Y. Chung
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Xiao Liu
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW 2500, Australia
| | - Chung-Yu Wu
- Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
| | - Guan-Yu Chen
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
- Department of Electronics and Electrical Engineering, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan
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15
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Balakrishnan G, Song J, Mou C, Bettinger CJ. Recent Progress in Materials Chemistry to Advance Flexible Bioelectronics in Medicine. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2106787. [PMID: 34751987 PMCID: PMC8917047 DOI: 10.1002/adma.202106787] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/15/2021] [Indexed: 05/09/2023]
Abstract
Designing bioelectronic devices that seamlessly integrate with the human body is a technological pursuit of great importance. Bioelectronic medical devices that reliably and chronically interface with the body can advance neuroscience, health monitoring, diagnostics, and therapeutics. Recent major efforts focus on investigating strategies to fabricate flexible, stretchable, and soft electronic devices, and advances in materials chemistry have emerged as fundamental to the creation of the next generation of bioelectronics. This review summarizes contemporary advances and forthcoming technical challenges related to three principal components of bioelectronic devices: i) substrates and structural materials, ii) barrier and encapsulation materials, and iii) conductive materials. Through notable illustrations from the literature, integration and device fabrication strategies and associated challenges for each material class are highlighted.
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Affiliation(s)
| | - Jiwoo Song
- Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA, 15213, USA
| | - Chenchen Mou
- Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA, 15213, USA
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16
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de Ruyter van Steveninck J, Güçlü U, van Wezel R, van Gerven M. End-to-end optimization of prosthetic vision. J Vis 2022; 22:20. [PMID: 35703408 PMCID: PMC8899855 DOI: 10.1167/jov.22.2.20] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Neural prosthetics may provide a promising solution to restore visual perception in some forms of blindness. The restored prosthetic percept is rudimentary compared to normal vision and can be optimized with a variety of image preprocessing techniques to maximize relevant information transfer. Extracting the most useful features from a visual scene is a nontrivial task and optimal preprocessing choices strongly depend on the context. Despite rapid advancements in deep learning, research currently faces a difficult challenge in finding a general and automated preprocessing strategy that can be tailored to specific tasks or user requirements. In this paper, we present a novel deep learning approach that explicitly addresses this issue by optimizing the entire process of phosphene generation in an end-to-end fashion. The proposed model is based on a deep auto-encoder architecture and includes a highly adjustable simulation module of prosthetic vision. In computational validation experiments, we show that such an approach is able to automatically find a task-specific stimulation protocol. The results of these proof-of-principle experiments illustrate the potential of end-to-end optimization for prosthetic vision. The presented approach is highly modular and our approach could be extended to automated dynamic optimization of prosthetic vision for everyday tasks, given any specific constraints, accommodating individual requirements of the end-user.
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Affiliation(s)
- Jaap de Ruyter van Steveninck
- Department of Artificial Intelligence, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
- Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Umut Güçlü
- Department of Artificial Intelligence, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Richard van Wezel
- Department of Biophysics, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
- Biomedical Signal and Systems, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Marcel van Gerven
- Department of Artificial Intelligence, Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
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17
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Haji Ghaffari D, Akwaboah AD, Mirzakhalili E, Weiland JD. Real-Time Optimization of Retinal Ganglion Cell Spatial Activity in Response to Epiretinal Stimulation. IEEE Trans Neural Syst Rehabil Eng 2021; 29:2733-2741. [PMID: 34941514 PMCID: PMC8851408 DOI: 10.1109/tnsre.2021.3138297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Retinal prostheses aim to improve visual perception in patients blinded by photoreceptor degeneration. However, shape and letter perception with these devices is currently limited due to low spatial resolution. Previous research has shown the retinal ganglion cell (RGC) spatial activity and phosphene shapes can vary due to the complexity of retina structure and electrode-retina interactions. Visual percepts elicited by single electrodes differ in size and shapes for different electrodes within the same subject, resulting in interference between phosphenes and an unclear image. Prior work has shown that better patient outcomes correlate with spatially separate phosphenes. In this study we use calcium imaging, in vitro retina, neural networks (NN), and an optimization algorithm to demonstrate a method to iteratively search for optimal stimulation parameters that create focal RGC activation. Our findings indicate that we can converge to stimulation parameters that result in focal RGC activation by sampling less than 1/3 of the parameter space. A similar process implemented clinically can reduce time required for optimizing implant operation and enable personalized fitting of retinal prostheses.
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18
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Yi X, Zheng W, Cao H, Wang S, Feng X, Yang Z. Wireless Power Transmission for Implantable Medical Devices Using Focused Ultrasound and a Miniaturized 1-3 Piezoelectric Composite Receiving Transducer. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:3592-3598. [PMID: 34357865 DOI: 10.1109/tuffc.2021.3103099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Wireless power transmission (WPT) using ultrasound is a promising way for wirelessly recharging implantable medical devices (IMDs). However, the transmitted power using ultrasound so far is insufficient for driving the existing IMDs. Moreover, the size of the receiving transducer is larger, which is not suitable for implantation. To increase the output power and reduce the size of the implantable receiver, this article presents a method of combining focused ultrasound with a miniaturized 1-3 piezoelectric composite receiving transducer to produce higher electrical power. An analytical fluid-structure interaction model is constructed to fully understand the operating mechanism of the receiving transducer under ultrasonic force. In our experiments, a miniaturized 1-3 piezoelectric composite receiving transducer with a diameter of 3.7 mm was used. The output power generated from the receiving transducer reached 60 mW at a distance of 150 mm. In vitro and in vivo animal experiments proved that the miniaturized transducer could successfully receive focused ultrasonic energy and convert it to electrical power. The method presented and the electrical power that we obtained can provide a valuable reference for wirelessly charging of IMDs.
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19
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Eggenberger SC, James NL, Ho C, Eamegdool SS, Tatarinoff V, Craig NA, Gow BS, Wan S, Dodds CWD, La Hood D, Gilmour A, Donahoe SL, Krockenberger M, Tumuluri K, da Cruz MJ, Grigg JR, McCluskey P, Lovell NH, Madigan MC, Fung AT, Suaning GJ. Implantation and long-term assessment of the stability and biocompatibility of a novel 98 channel suprachoroidal visual prosthesis in sheep. Biomaterials 2021; 279:121191. [PMID: 34768150 DOI: 10.1016/j.biomaterials.2021.121191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 09/28/2021] [Accepted: 10/18/2021] [Indexed: 11/25/2022]
Abstract
Severe visual impairment can result from retinal degenerative diseases such as retinitis pigmentosa, which lead to photoreceptor cell death. These pathologies result in extensive neural and glial remodelling, with survival of excitable retinal neurons that can be electrically stimulated to elicit visual percepts and restore a form of useful vision. The Phoenix99 Bionic Eye is a fully implantable visual prosthesis, designed to stimulate the retina from the suprachoroidal space. In the current study, nine passive devices were implanted in an ovine model from two days to three months. The impact of the intervention and implant stability were assessed using indirect ophthalmoscopy, infrared imaging, and optical coherence tomography to establish the safety profile of the surgery and the device. The biocompatibility of the device was evaluated using histopathological analysis of the tissue surrounding the electrode array, with a focus on the health of the retinal cells required to convey signals to the brain. Appropriate stability of the electrode array was demonstrated, and histological analysis shows that the fibrotic and inflammatory response to the array was mild. Promising evidence of the safety and potential of the Phoenix99 Bionic Eye to restore a sense of vision to the severely visually impaired was obtained.
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Affiliation(s)
- Samuel C Eggenberger
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia
| | - Natalie L James
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Cherry Ho
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Steven S Eamegdool
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia
| | - Veronika Tatarinoff
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Naomi A Craig
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Barry S Gow
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Susan Wan
- The Westmead Institute for Medical Research, Westmead, Australia
| | - Christopher W D Dodds
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Donna La Hood
- Brien Holden Vision Institute, Sydney, Australia; School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, Australia
| | - Aaron Gilmour
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Shannon L Donahoe
- Veterinary Pathology Diagnostic Services, Sydney School of Veterinary Science, University of Sydney, Sydney, Australia
| | - Mark Krockenberger
- Veterinary Pathology Diagnostic Services, Sydney School of Veterinary Science, University of Sydney, Sydney, Australia
| | - Krishna Tumuluri
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Westmead Clinical School, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; Department of Ophthalmology, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia
| | - Melville J da Cruz
- Department of Otolaryngology, Westmead Hospital, University of Sydney, Sydney, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - John R Grigg
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Peter McCluskey
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia
| | - Michele C Madigan
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; School of Optometry and Vision Science, University of New South Wales (UNSW), Sydney, Australia
| | - Adrian T Fung
- Save Sight Institute, The University of Sydney, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, Australia; Westmead Clinical School, Specialty of Clinical Ophthalmology and Eye Health, Faculty of Medicine and Health, University of Sydney, Sydney, Australia; Department of Ophthalmology, Faculty of Medicine and Health Sciences, Macquarie University, New South Wales, Australia
| | - Gregg J Suaning
- School of Biomedical Engineering, Faculty of Engineering, University of Sydney, Sydney, Australia; Graduate School of Biomedical Engineering, University of New South Wales (UNSW), Sydney, Australia.
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20
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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.
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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
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21
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Yang SY, Sencadas V, You SS, Jia NZX, Srinivasan SS, Huang HW, Ahmed AE, Liang JY, Traverso G. Powering Implantable and Ingestible Electronics. ADVANCED FUNCTIONAL MATERIALS 2021; 31:2009289. [PMID: 34720792 PMCID: PMC8553224 DOI: 10.1002/adfm.202009289] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Indexed: 05/28/2023]
Abstract
Implantable and ingestible biomedical electronic devices can be useful tools for detecting physiological and pathophysiological signals, and providing treatments that cannot be done externally. However, one major challenge in the development of these devices is the limited lifetime of their power sources. The state-of-the-art of powering technologies for implantable and ingestible electronics is reviewed here. The structure and power requirements of implantable and ingestible biomedical electronics are described to guide the development of powering technologies. These powering technologies include novel batteries that can be used as both power sources and for energy storage, devices that can harvest energy from the human body, and devices that can receive and operate with energy transferred from exogenous sources. Furthermore, potential sources of mechanical, chemical, and electromagnetic energy present around common target locations of implantable and ingestible electronics are thoroughly analyzed; energy harvesting and transfer methods befitting each energy source are also discussed. Developing power sources that are safe, compact, and have high volumetric energy densities is essential for realizing long-term in-body biomedical electronics and for enabling a new era of personalized healthcare.
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Affiliation(s)
- So-Yoon Yang
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Vitor Sencadas
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; School of Mechanical, Materials & Mechatronics Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Siheng Sean You
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Neil Zi-Xun Jia
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Shriya Sruthi Srinivasan
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Hen-Wei Huang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Abdelsalam Elrefaey Ahmed
- Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jia Ying Liang
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Giovanni Traverso
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Division of Gastroenterology, Hepatology and Endoscopy, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
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22
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Valle ED, Welle EJ, Chestek CA, Weiland JD. Compositional and morphological properties of platinum-iridium electrodeposited on carbon fiber microelectrodes. J Neural Eng 2021; 18:10.1088/1741-2552/ac20bb. [PMID: 34428753 PMCID: PMC10756281 DOI: 10.1088/1741-2552/ac20bb] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 08/24/2021] [Indexed: 11/12/2022]
Abstract
Objective. Neural interfaces based on carbon fiber (CF) electrodes have demonstrated key positive attributes such as minimal foreign body response and mechanical strength to self-insert in brain tissue. However, carbon does not form a low impedance electrode interface with neural tissue. Electrodeposited platinum iridium (PtIr) has been used to improve electrode interface properties for metallic bioelectrodes.Approach. In this study, a PtIr electrodeposition process has been performed on CF microelectrode arrays to improve the interfacial properties of these arrays. We study the film morphology and composition as well as electrode durability and impedance.Results. A PtIr coating with a composition of 70% Pt, 30% Ir and a thickness of ∼400 nm was observed. Pt and Ir were evenly distributed within the film. Impedance was decreased by 89% @ 1 kHz. Accelerated soak testing in a heated (T= 50∘C) saline solution showed impedance increase (@ 1 kHz) of ∼12% after 36 days (89 equivalent) of soaking.
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Affiliation(s)
- Elena della Valle
- Biomedical Engineering Department, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Elissa J Welle
- Biomedical Engineering Department, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Cynthia A Chestek
- Biomedical Engineering Department, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - James D Weiland
- Biomedical Engineering Department, University of Michigan, Ann Arbor, MI, United States of America
- Department of Ophthalmology and Visual Sciences, University of Michigan Kellogg Eye Center, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
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23
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EPIRETINAL FIBROSIS REMOVAL IN AN ARGUS II-IMPLANTED EYE: Histological Characteristics and Functional Results. Retina 2021; 40:2403-2409. [PMID: 32195788 DOI: 10.1097/iae.0000000000002780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE 1) To investigate morphologic and histochemical characteristics of an epiretinal fibrosis removed in an Argus II-implanted eye; 2) to evaluate the Argus II function before and after the fibrosis removal, and 3) to compare morphologic and functional data. METHODS Fibrosis, which developed between the Argus II prosthesis and the retina two years after implant, was surgically removed. Its morphologic and histochemical characteristics were evaluated both in light and transmission electron microscopy, with special stains and immunohistochemistry. The Argus II function was evaluated during the follow-up before surgical removal and 1 month later. RESULTS Fibrosis was successfully removed. It was composed of a fibrotic tissue with spindle cells arranged in nodular aggregates with a symmetric distribution, mixed with an inflammatory infiltrate. Extra- and intracellular, irregular, small iron particles were found and confirmed ultrastructural characterization with degenerative cellular changes. The repositioned Argus II restored, and its function was partially nearly to normal values 1 month after surgery. CONCLUSION Fibrosis can develop between the Argus II and the retina with increasing reduced function. Morphologic characteristics of the removed fibrosis suggested a pathogenesis based on an inflammatory process involved in a foreign body reaction with progressing connective tissue deposition leading to sclerosis. Adequate clinical follow-up is critical to successful removal of the fibrosis with reactivation of the Argus II function.
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Culaclii S, Wang PM, Taccola G, Yang W, Bailey B, Chen YP, Lo YK, Liu W. A Biomimetic, SoC-Based Neural Stimulator for Novel Arbitrary-Waveform Stimulation Protocols. Front Neurosci 2021; 15:697731. [PMID: 34393710 PMCID: PMC8358079 DOI: 10.3389/fnins.2021.697731] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 07/07/2021] [Indexed: 11/15/2022] Open
Abstract
Novel neural stimulation protocols mimicking biological signals and patterns have demonstrated significant advantages as compared to traditional protocols based on uniform periodic square pulses. At the same time, the treatments for neural disorders which employ such protocols require the stimulator to be integrated into miniaturized wearable devices or implantable neural prostheses. Unfortunately, most miniaturized stimulator designs show none or very limited ability to deliver biomimetic protocols due to the architecture of their control logic, which generates the waveform. Most such designs are integrated into a single System-on-Chip (SoC) for the size reduction and the option to implement them as neural implants. But their on-chip stimulation controllers are fixed and limited in memory and computing power, preventing them from accommodating the amplitude and timing variances, and the waveform data parameters necessary to output biomimetic stimulation. To that end, a new stimulator architecture is proposed, which distributes the control logic over three component tiers - software, microcontroller firmware and digital circuits of the SoC, which is compatible with existing and future biomimetic protocols and with integration into implantable neural prosthetics. A portable prototype with the proposed architecture is designed and demonstrated in a bench-top test with various known biomimetic output waveforms. The prototype is also tested in vivo to deliver a complex, continuous biomimetic stimulation to a rat model of a spinal-cord injury. By delivering this unique biomimetic stimulation, the device is shown to successfully reestablish the connectivity of the spinal cord post-injury and thus restore motor outputs in the rat model.
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Affiliation(s)
- Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Po-Min Wang
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Giuliano Taccola
- Neuroscience Department, International School for Advanced Studies, Trieste, Italy
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, United States
| | - William Yang
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Brett Bailey
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Yan-Peng Chen
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, CA, United States
| | - Yi-Kai Lo
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Niche Biomedical Inc., Los Angeles, CA, United States
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, Los Angeles, CA, United States
- Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, CA, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, United States
- Brain Research Institute, University of California, Los Angeles, Los Angeles, CA, United States
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Spencer MJ, Kameneva T, Grayden DB, Burkitt AN, Meffin H. Neural activity shaping utilizing a partitioned target pattern. J Neural Eng 2021; 18. [PMID: 33684894 DOI: 10.1088/1741-2552/abecc4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 03/08/2021] [Indexed: 11/11/2022]
Abstract
Electrical stimulation of neural tissue is used in both clinical and experimental devices to evoke a desired spatiotemporal pattern of neural activity. These devices induce a local field that drives neural activation, referred to as an activating function or generator signal. In visual prostheses, the spread of generator signal from each electrode within the neural tissue results in a spread of visual perception, referred to as a phosphene. In cases where neighboring phosphenes overlap, it is desirable to use current steering or neural activity shaping strategies to manipulate the generator signal between the electrodes to provide greater control over the total pattern of neural activity. Applying opposite generator signal polarities in neighboring regions of the retina forces the generator signal to pass through zero at an intermediate point, thus inducing low neural activity that may be perceived as a high-contrast line. This approach provides a form of high contrast visual perception, but it requires partitioning of the target pattern into those regions that use positive or negative generator signals. This discrete optimization is an NP-hard problem that is subject to being trapped in detrimental local minima. This investigation proposes a new partitioning method using image segmentation to determine the most beneficial positive and negative generator signal regions. Utilizing a database of 1000 natural images, the method is compared to alternative approaches based upon the mean squared error of the outcome. Under nominal conditions and with a set computation limit, partitioning provided improvement for 32% of these images. This percentage increased to 89% when utilizing image pre-processing to emphasize perceptual features of the images. The percentage of images that were dealt with most effectively with image segmentation increased as lower computation limits were imposed on the algorithms.
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Affiliation(s)
- Martin J Spencer
- Department of Biomedical Engineering, The University of Melbourne - Parkville Campus, Parkville, Melbourne, Victoria, 3010, AUSTRALIA
| | - Tatiana Kameneva
- Telecommunication, Electrical, Robotics and Biomedical Engineering, Swinburne University of Technology, Hawthorn, Hawthorn, Victoria, 3122, AUSTRALIA
| | - David B Grayden
- Department of Biomedical Engineering, The University of Melbourne - Parkville Campus, Parkville, Melbourne, Victoria, 3010, AUSTRALIA
| | - Anthony N Burkitt
- Department of Biomedical Engineering, The University of Melbourne - Parkville Campus, Parkville, Melbourne, Victoria, 3010, AUSTRALIA
| | - Hamish Meffin
- Australian College of Optometry, Parkville, Carlton, Victoria, 3010, AUSTRALIA
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Lu G, Qian X, Castillo J, Li R, Jiang L, Lu H, Kirk Shung K, Humayun MS, Thomas BB, Zhou Q. Transcranial Focused Ultrasound for Noninvasive Neuromodulation of the Visual Cortex. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2021; 68:21-28. [PMID: 32746196 PMCID: PMC8153235 DOI: 10.1109/tuffc.2020.3005670] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Currently, blindness cannot be cured and patients' living quality can be compromised severely. Ultrasonic (US) neuromodulation is a promising technology for the development of noninvasive cortical visual prosthesis. We investigated the feasibility of transcranial focused ultrasound (tFUS) for noninvasive stimulation of the visual cortex (VC) to develop improved visual prosthesis. tFUS was used to successfully evoke neural activities in the VC of both normal and retinal degenerate (RD) blind rats. Our results showed that blind rats showed more robust responses to ultrasound stimulation when compared with normal rats. ( , two-sample t-test). Three different types of ultrasound waveforms were used in the three experimental groups. Different types of cortical activities were observed when different US waveforms were used. In all rats, when stimulated with continuous ultrasound waves, only short-duration responses were observed at "US on and off" time points. In comparison, pulsed waves (PWs) evoked longer low-frequency responses. Testing different parameters of PWs showed that a pulse repetition frequency higher than 100 Hz is required to obtain the low-frequency responses. Based on the observed cortical activities, we inferred that acoustic radiation force (ARF) is the predominant physical mechanism of ultrasound neuromodulation.
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Bio-Compatibility and Bio-Insulation of Implantable Electrode Prosthesis Ameliorated by A-174 Silane Primed Parylene-C Deposited Embedment. MICROMACHINES 2020; 11:mi11121064. [PMID: 33266050 PMCID: PMC7761135 DOI: 10.3390/mi11121064] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/24/2020] [Accepted: 11/29/2020] [Indexed: 11/16/2022]
Abstract
Microelectrodes for pain management, neural prosthesis or assistances have a huge medical demand, such as the application of pain management chip or retinal prosthesis addressed on age-related macular degeneration (AMD) and the retinitis pigmentosa (RP). Due to lifelong implanted in human body and direct adhesion of neural tissues, the electrodes and associated insulation materials should possess an ideal bio-compatibility, including non-cytotoxicity and no safety concern elicited by immune responses. Our goal intended to develop retinal prosthesis, an electrical circuit chip used for assisting neural electrons transmission on retina and ameliorating the retinal disability. Therefore, based on the ISO 10993 guidance for implantable medical devices, the electrode prosthesis with insulation material has to conduct bio-compatibility assessment including cytotoxicity, hemolysis, (skin) irritation and pathological implantation examinations. In this study, we manufactured inter-digitated electrode (IDE) chips mimic the electrode prosthesis through photolithography. The titanium and platinum composites were deposited onto a silicon wafer to prepare an electric circuit to mimic the electrode used in retinal prosthesis manufacture, which further be encapsulated to examine the bio-compatibility in compliance with ISO 10993 and ASTM guidance specifically for implantable medical devices. Parylene-C, polyimide and silicon carbide were selected as materials for electrode encapsulation in comparison. Our data revealed parylene-C coating showed a significant excellence on bio-insulation and bio-compatibility specifically addressed on implantable neuron stimulatory devices and provided an economic procedure to package the electrode prosthesis. Therefore, parylene C encapsulation should serve as a consideration for future application on retinal prosthesis manufacture and examination.
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Shire DB, Gingerich MD, Wong PI, Skvarla M, Cogan SF, Chen J, Wang W, Rizzo JF. Micro-Fabrication of Components for a High-Density Sub-Retinal Visual Prosthesis. MICROMACHINES 2020; 11:mi11100944. [PMID: 33086504 PMCID: PMC7603138 DOI: 10.3390/mi11100944] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/10/2020] [Accepted: 10/13/2020] [Indexed: 01/30/2023]
Abstract
We present a retrospective of unique micro-fabrication problems and solutions that were encountered through over 10 years of retinal prosthesis product development, first for the Boston Retinal Implant Project initiated at the Massachusetts Institute of Technology and at Harvard Medical School’s teaching hospital, the Massachusetts Eye and Ear—and later at the startup company Bionic Eye Technologies, by some of the same personnel. These efforts culminated in the fabrication and assembly of 256+ channel visual prosthesis devices having flexible multi-electrode arrays that were successfully implanted sub-retinally in mini-pig animal models as part of our pre-clinical testing program. We report on the processing of the flexible multi-layered, planar and penetrating high-density electrode arrays, surgical tools for sub-retinal implantation, and other parts such as coil supports that facilitated the implantation of the peri-ocular device components. We begin with an overview of the implantable portion of our visual prosthesis system design, and describe in detail the micro-fabrication methods for creating the parts of our system that were assembled outside of our hermetically-sealed electronics package. We also note the unique surgical challenges that sub-retinal implantation of our micro-fabricated components presented, and how some of those issues were addressed through design, materials selection, and fabrication approaches.
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Affiliation(s)
- Douglas B. Shire
- Bionic Eye Technologies, Inc., Ithaca, NY 14850, USA; (M.D.G.); (P.I.W.)
- Correspondence: ; Tel.: +1-607-339-7085
| | | | - Patricia I. Wong
- Bionic Eye Technologies, Inc., Ithaca, NY 14850, USA; (M.D.G.); (P.I.W.)
| | - Michael Skvarla
- Cornell NanoScale Science and Technology Facility, Ithaca, NY 14853, USA;
| | - Stuart F. Cogan
- Department of Bioengineering, University of Texas, Dallas, Richardson, TX 75080, USA;
| | - Jinghua Chen
- Department of Ophthalmology, University of Florida, Gainesville, FL 32611, USA;
| | - Wei Wang
- Department of Ophthalmology, University of Louisville, Louisville, KY 40292, USA;
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Zhao J, Ghannam R, Htet KO, Liu Y, Law M, Roy VAL, Michel B, Imran MA, Heidari H. Self-Powered Implantable Medical Devices: Photovoltaic Energy Harvesting Review. Adv Healthc Mater 2020; 9:e2000779. [PMID: 32729228 DOI: 10.1002/adhm.202000779] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/09/2020] [Indexed: 12/21/2022]
Abstract
Implantable technologies are becoming more widespread for biomedical applications that include physical identification, health diagnosis, monitoring, recording, and treatment of human physiological traits. However, energy harvesting and power generation beneath the human tissue are still a major challenge. In this regard, self-powered implantable devices that scavenge energy from the human body are attractive for long-term monitoring of human physiological traits. Thanks to advancements in material science and nanotechnology, energy harvesting techniques that rely on piezoelectricity, thermoelectricity, biofuel, and radio frequency power transfer are emerging. However, all these techniques suffer from limitations that include low power output, bulky size, or low efficiency. Photovoltaic (PV) energy conversion is one of the most promising candidates for implantable applications due to their higher-power conversion efficiencies and small footprint. Herein, the latest implantable energy harvesting technologies are surveyed. A comparison between the different state-of-the-art power harvesting methods is also provided. Finally, recommendations are provided regarding the feasibility of PV cells as an in vivo energy harvester, with an emphasis on skin penetration, fabrication, encapsulation, durability, biocompatibility, and power management.
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Affiliation(s)
- Jinwei Zhao
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Rami Ghannam
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Kaung Oo Htet
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Yuchi Liu
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Man‐kay Law
- State Key Laboratory of Analog and Mixed‐Signal VLSI AMSV University of Macao Macao China
| | | | - Bruno Michel
- Smart System Integration IBM Research GmbH Rueschlikon CH‐8803 Switzerland
| | - Muhammad Ali Imran
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
| | - Hadi Heidari
- James Watts school of Engineering University of Glasgow Glasgow G12 8QQ UK
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30
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Lozano A, Suárez JS, Soto-Sánchez C, Garrigós J, Martínez-Alvarez JJ, Ferrández JM, Fernández E. Neurolight: A Deep Learning Neural Interface for Cortical Visual Prostheses. Int J Neural Syst 2020; 30:2050045. [DOI: 10.1142/s0129065720500458] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Visual neuroprosthesis, that provide electrical stimulation along several sites of the human visual system, constitute a potential tool for vision restoration for the blind. Scientific and technological progress in the fields of neural engineering and artificial vision comes with new theories and tools that, along with the dawn of modern artificial intelligence, constitute a promising framework for the further development of neurotechnology. In the framework of the development of a Cortical Visual Neuroprosthesis for the blind (CORTIVIS), we are now facing the challenge of developing not only computationally powerful tools and flexible approaches that will allow us to provide some degree of functional vision to individuals who are profoundly blind. In this work, we propose a general neuroprosthesis framework composed of several task-oriented and visual encoding modules. We address the development and implementation of computational models of the firing rates of retinal ganglion cells and design a tool — Neurolight — that allows these models to be interfaced with intracortical microelectrodes in order to create electrical stimulation patterns that can evoke useful perceptions. In addition, the developed framework allows the deployment of a diverse array of state-of-the-art deep-learning techniques for task-oriented and general image pre-processing, such as semantic segmentation and object detection in our system’s pipeline. To the best of our knowledge, this constitutes the first deep-learning-based system designed to directly interface with the visual brain through an intracortical microelectrode array. We implement the complete pipeline, from obtaining a video stream to developing and deploying task-oriented deep-learning models and predictive models of retinal ganglion cells’ encoding of visual inputs under the control of a neurostimulation device able to send electrical train pulses to a microelectrode array implanted at the visual cortex.
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Affiliation(s)
- Antonio Lozano
- Departamento de Electrónica, Tecnología de Computadoras y Proyectos, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain
| | - Juan Sebastián Suárez
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Alicante, Spain
- CIBER-BBN, 28029 Madrid, Spain
| | - Cristina Soto-Sánchez
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Alicante, Spain
- CIBER-BBN, 28029 Madrid, Spain
| | - Javier Garrigós
- Departamento de Electrónica, Tecnología de Computadoras y Proyectos, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain
| | - J. Javier Martínez-Alvarez
- Departamento de Electrónica, Tecnología de Computadoras y Proyectos, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain
| | - J. Manuel Ferrández
- Departamento de Electrónica, Tecnología de Computadoras y Proyectos, Universidad Politécnica de Cartagena, 30202 Cartagena, Spain
| | - Eduardo Fernández
- Instituto de Bioingeniería, Universidad Miguel Hernández, 03202 Alicante, Spain
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31
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Rustogi P, Judy JW. Electrical Isolation Performance of Microgasket Technology for Implant Packaging. ... ELECTRONIC COMPONENTS & TECHNOLOGY CONFERENCE. ELECTRONIC COMPONENTS & TECHNOLOGY CONFERENCE 2020; 2020:1601-1607. [PMID: 35586778 PMCID: PMC9112188 DOI: 10.1109/ectc32862.2020.00251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
High-channel-count neural interfaces are typically packaged by being permanently bonded to their packaged electronics followed by encapsulation. Such interfaces are often intimately integrated into neural tissue, their removal to replace the battery or upgrade electronics is not undesirable. Gaskets are widely used to provide liquid/electrical isolation and to seal the connection between two or more mating parts. Pressure-driven microgaskets are well established in the field of microfluidics. Although rematable microgaskets for fluidic interconnects exist, the use of microgaskets for electrical isolation have not been demonstrated. Our approach is to electrically isolate 2-D arrays of contact pads using a compressible silicone microgasket. Electrochemical impedance spectroscopy (EIS) was used to quantify the electrical isolation of the microgasket on contact pads, which were formed in a polyimide flex circuit, as a function of frequency after being soaked in saline. Experiments have shown that the compressed sub-millimeter PDMSe microgasket can provide excellent isolation (i.e., >30 MΩ at 1 KHz) that is comparable to the other more conventional packaging methods, such as encapsulation in polydimethylsiloxane elastomer (PDMSe) or parylene-C. Our microgasket-based approach should be scalable to high channel counts and high channel densities enabling much smaller and higher-performance neural implants.
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Affiliation(s)
- Paritosh Rustogi
- Electrical and Computer Engineering Department, Nanoscience Institute for Medical and Engineering Technology, University of Florida, Gainesville, USA
| | - Jack W Judy
- Electrical and Computer Engineering Department, Nanoscience Institute for Medical and Engineering Technology, University of Florida, Gainesville, USA
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32
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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.
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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
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33
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Zeinali K, Khorasani MT, Rashidi A, Daliri Joupari M. Preparation and characterization of graphene oxide aerogel/gelatin as a hybrid scaffold for application in nerve tissue engineering. INT J POLYM MATER PO 2020. [DOI: 10.1080/00914037.2020.1760269] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Khdijeh Zeinali
- Department of Science and Research branch, Islamic Azad University, Tehran, Iran
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34
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Stamp MEM, Tong W, Ganesan K, Prawer S, Ibbotson MR, Garrett DJ. 3D Diamond Electrode Array for High-Acuity Stimulation in Neural Tissue. ACS APPLIED BIO MATERIALS 2020; 3:1544-1552. [DOI: 10.1021/acsabm.9b01165] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Melanie E. M. Stamp
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Wei Tong
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria 3053, Australia
- Department of Optometry and Vision Sciences, Melbourne School of Health Sciences, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Kumaravelu Ganesan
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Steven Prawer
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Michael R. Ibbotson
- National Vision Research Institute, Australian College of Optometry, Carlton, Victoria 3053, Australia
| | - David J. Garrett
- School of Physics, The University of Melbourne, Melbourne, Victoria 3010, Australia
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35
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Sanchez-Garcia M, Martinez-Cantin R, Guerrero JJ. Semantic and structural image segmentation for prosthetic vision. PLoS One 2020; 15:e0227677. [PMID: 31995568 PMCID: PMC6988941 DOI: 10.1371/journal.pone.0227677] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 12/24/2019] [Indexed: 01/12/2023] Open
Abstract
Prosthetic vision is being applied to partially recover the retinal stimulation of visually impaired people. However, the phosphenic images produced by the implants have very limited information bandwidth due to the poor resolution and lack of color or contrast. The ability of object recognition and scene understanding in real environments is severely restricted for prosthetic users. Computer vision can play a key role to overcome the limitations and to optimize the visual information in the prosthetic vision, improving the amount of information that is presented. We present a new approach to build a schematic representation of indoor environments for simulated phosphene images. The proposed method combines a variety of convolutional neural networks for extracting and conveying relevant information about the scene such as structural informative edges of the environment and silhouettes of segmented objects. Experiments were conducted with normal sighted subjects with a Simulated Prosthetic Vision system. The results show good accuracy for object recognition and room identification tasks for indoor scenes using the proposed approach, compared to other image processing methods.
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Affiliation(s)
- Melani Sanchez-Garcia
- Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza, Spain
| | - Ruben Martinez-Cantin
- Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza, Spain
| | - Jose J. Guerrero
- Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza, Spain
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36
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Li G, Wang F, Yang W, Yang J, Wang Y, Wang W, Liu L. Development of an image biosensor based on an optogenetically engineered cell for visual prostheses. NANOSCALE 2019; 11:13213-13218. [PMID: 31184360 DOI: 10.1039/c9nr01688k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Visual prostheses provide blind patients with artificial vision via electrical stimulation of surviving visual cells resulting in partial restoration of vision in many patients. However, high-resolution visual perception, long-term biocompatibility and safety remain the significant challenges of existing visual prostheses. Here, we present a novel method to develop a new visual prosthesis using living cells as integrated electronics and implantable microelectrodes. The living cells modified with channelrhodopsin-2 showed excellent light-sensitive properties and encoded image information with cellular deformations triggered by light stimulation. The photoresponsive properties of the cells were determined using a single pixel imaging system, which indicated that the cells can act as a good light-sensitive biosensor. Additionally, the imaging feasibility of the cells was further validated through successful and clear imaging of several object scenes using the same system. This work represents a step toward the design and use of living cells as an image biosensor for the development of a new generation of high-resolution visual prostheses.
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Affiliation(s)
- Gongxin Li
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China. and Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China and Key Laboratory of Advanced Process Control for Light Industry (Ministry of Education), Institute of Automation, Jiangnan University, Wuxi 214122, China
| | - Feifei Wang
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
| | - Wenguang Yang
- School of Electromechanical and Automotive Engineering, Yantai University, Yantai 264005, China
| | - Jia Yang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China. and Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China and University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuechao Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China. and Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China
| | - Wenxue Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China. and Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China
| | - Lianqing Liu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China. and Institutes for Robotics and Intelligent Manufacturing, Chinese Academy of Sciences, Shenyang 110016, China
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37
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Abstract
Visual prostheses serve to restore visual function following acquired blindness. Acquired blindness (as opposed to congenital blindness) has many causes, including diseases such as retinitis pigmentosa, glaucoma, and macular degeneration, or trauma such as caused by automobile accident or blast damage from explosions. Many of the blindness-causing diseases target the retina or other ocular structure. Often, despite the loss of sensitivity to light, the remainder of the visual pathway is still functional, enabling electrical devices to deliver effective and meaningful visual information to the brain via arrays of electrodes. These arrays can be placed in any part of the early visual pathway, such as the retina, optic nerve, lateral geniculate nucleus, or visual cortex. A camera or other imaging source is used to drive electrical stimulation of remaining healthy cells or structures to create artificial vision and provide restoration of function. In this review, each approach to visual prostheses is described, including advantages and disadvantages as well as assessments of the current state of the art. Most of the work to-date has been targeting stimulation of (a) the retina, with three devices approved for general use and two more in clinical testing; (b) the lateral geniculate nucleus, with efforts still in the pre-clinical stage; and (c) the cortex, with three devices in clinical testing and none currently approved for general use despite the longest history of investigation of the three major approaches. Each class of device has different medical indications, and different levels of invasiveness required for implantation. All contemporary devices deliver relatively poor vision. There has been remarkable progress since the first proof-of-concept demonstration that used stimulation of the primary visual cortex, with the field exploring all viable options for restoration of function. Much of the progress has been recent, driven by advances in microelectronics and biocompatibility. With three devices currently approved for general use in various parts of the world, and a handful of additional devices well along in the pipeline toward approval, prospects for wide deployment of a device-based therapy to treat acquired blindness are good.
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Wang PM, Culaclii S, Yang W, Long Y, Massachi J, Lo YK, Liu W. A Novel Biomimetic Stimulator System for Neural Implant. INTERNATIONAL IEEE/EMBS CONFERENCE ON NEURAL ENGINEERING : [PROCEEDINGS]. INTERNATIONAL IEEE EMBS CONFERENCE ON NEURAL ENGINEERING 2019; 2019:843-846. [PMID: 31178980 DOI: 10.1109/ner.2019.8716942] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Electrical stimulation using non-periodic biomimetic stimulation pattern has been shown to be effective in various critical biomedical applications. However, the existing programmable stimulators that support this protocol are non-portable and have architectures that are not translatable to wearable or implantable applications. In this work, we present a 32-channel neural stimulator system based on an implantable System-On-Chip (SoC) that addresses these technological challenges. The system is designed to be portable, powered by a single battery, wirelessly controlled, and versatile to perform concurrent multi-channel stimulation with independent arbitrary waveforms. The experimental results demonstrate multi-channel stimulation mimicking electromyography (EMG) waveforms and randomly-spaced stimulation pulses mimicking neuronal firing patterns. This compact and highly flexible prototype can support various neuromodulation researches and animal studies and serves as a precursor for the development of the next generation implantable biomimetic stimulator.
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Affiliation(s)
- Po-Min Wang
- Department of Bioengineering, University of California, Los Angeles, CA, 90095, USA
| | - Stanislav Culaclii
- Department of Bioengineering, University of California, Los Angeles, CA, 90095, USA
| | - William Yang
- Department of Computer Science, University of California, Los Angeles, CA, 90095, USA
| | - Yan Long
- College of Electrical Engineering, Zhijiang University, Hangzhou, 310027, China
| | - Jonathan Massachi
- Department of Bioengineering, University of California, Los Angeles, CA, 90095, USA
| | - Yi-Kai Lo
- Niche Biomedical Inc., Los Angeles, CA 90095, USA
| | - Wentai Liu
- Department of Bioengineering, University of California, Los Angeles, CA, 90095, USA
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Who Will Be the Members of Society 5.0? Towards an Anthropology of Technologically Posthumanized Future Societies. SOCIAL SCIENCES 2019. [DOI: 10.3390/socsci8050148] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The Government of Japan’s “Society 5.0” initiative aims to create a cyber-physical society in which (among other things) citizens’ daily lives will be enhanced through increasingly close collaboration with artificially intelligent systems. However, an apparent paradox lies at the heart of efforts to create a more “human-centered” society in which human beings will live alongside a proliferating array of increasingly autonomous social robots and embodied AI. This study seeks to investigate the presumed human-centeredness of Society 5.0 by comparing its makeup with that of earlier societies. By distinguishing “technological” and “non-technological” processes of posthumanization and applying a phenomenological anthropological model, this study demonstrates: (1) how the diverse types of human and non-human members expected to participate in Society 5.0 differ qualitatively from one another; (2) how the dynamics that will shape the membership of Society 5.0 can be conceptualized; and (3) how the anticipated membership of Society 5.0 differs from that of Societies 1.0 through 4.0. This study describes six categories of prospective human and non-human members of Society 5.0 and shows that all six have analogues in earlier societies, which suggests that social scientific analysis of past societies may shed unexpected light on the nature of Society 5.0.
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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.
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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
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A Novel Racing Array Transducer for Noninvasive Ultrasonic Retinal Stimulation: A Simulation Study. SENSORS 2019; 19:s19081825. [PMID: 30999576 PMCID: PMC6514975 DOI: 10.3390/s19081825] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/27/2019] [Accepted: 04/03/2019] [Indexed: 12/26/2022]
Abstract
Neurostimulation has proved to be an effective method for the restoration of visual perception lost due to retinal diseases. However, the clinically available retinal neurostimulation method is based on invasive electrodes, making it a high-cost and high-risk procedure. Recently, ultrasound has been demonstrated to be an effective way to achieve noninvasive neurostimulation. In this work, a novel racing array transducer with a contact lens shape is proposed for ultrasonic retinal stimulation. The transducer is flexible and placed outside the eyeball, similar to the application of a contact lens. Ultrasound emitted from the transducer can reach the retina without passing through the lens, thus greatly minimizing the acoustic absorption in the lens. The discretized Rayleigh–Sommerfeld method was employed for the acoustic field simulation, and patterned stimulation was achieved. A 5 MHz racing array transducer with different element numbers was simulated to optimize the array configuration. The results show that a 512-element racing array is the most appropriate configuration considering the necessary tradeoff between the element number and the stimulation resolution. The stimulation resolution at a focus of 24 mm is about 0.6 mm. The obtained results indicate that the proposed racing array design of the ultrasound transducer can improve the feasibility of an ultrasound retinal prosthesis.
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Towards neural co-processors for the brain: combining decoding and encoding in brain-computer interfaces. Curr Opin Neurobiol 2019; 55:142-151. [PMID: 30954862 DOI: 10.1016/j.conb.2019.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 03/13/2019] [Accepted: 03/14/2019] [Indexed: 12/18/2022]
Abstract
The field of brain-computer interfaces is poised to advance from the traditional goal of controlling prosthetic devices using brain signals to combining neural decoding and encoding within a single neuroprosthetic device. Such a device acts as a 'co-processor' for the brain, with applications ranging from inducing Hebbian plasticity for rehabilitation after brain injury to reanimating paralyzed limbs and enhancing memory. We review recent progress in simultaneous decoding and encoding for closed-loop control and plasticity induction. To address the challenge of multi-channel decoding and encoding, we introduce a unifying framework for developing brain co-processors based on artificial neural networks and deep learning. These 'neural co-processors' can be used to jointly optimize cost functions with the nervous system to achieve desired behaviors ranging from targeted neuro-rehabilitation to augmentation of brain function.
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Davidsen RS, Hemanth S, Keller SS, Bek T, Hansen O. Evaluation of the capacitive behavior of 3D carbon electrodes for sub-retinal photovoltaic prosthesis. MICRO AND NANO ENGINEERING 2019. [DOI: 10.1016/j.mne.2019.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Rizzo S, Cinelli L, Finocchio L, Tartaro R, Santoro F, Gregori NZ. Assessment of Postoperative Morphologic Retinal Changes by Optical Coherence Tomography in Recipients of an Electronic Retinal Prosthesis Implant. JAMA Ophthalmol 2019; 137:272-278. [PMID: 30605209 PMCID: PMC6439717 DOI: 10.1001/jamaophthalmol.2018.6375] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 11/09/2018] [Indexed: 01/10/2023]
Abstract
Importance The postoperative retinal changes at the interface between an implant electrode array and the retina and whether these anatomic changes have an association with the patient visual performance are unknown. Objective To report morphologic changes in recipients of an Argus II Retinal Prosthesis. Design, Setting, and Participants This consecutive, noncomparative case series study included a retrospective review of the preoperative and postoperative optical coherence tomography of 33 eyes among 33 individuals who underwent Argus II Retinal Prosthesis System implantation between October 28, 2011, and June 8, 2017, at 2 different centers, by the same surgeon (S.R.). Thirteen patients received an implant at Azienda Ospedaliero Universitaria Pisana, Pisa, Italy, between October 28, 2011, and October 27, 2014, and 20 patients underwent surgery at Azienda Ospedaliera Universitaria Careggi, Florence, Italy, between December 20, 2014, and June 8, 2017. Patients were excluded if they did not reach the 6-month follow-up. Main Outcomes and Measures All patients were evaluated before surgery, during the first postoperative day, and at 1, 3, 6, 12, and 24 months (subsequently once a year, except for patient-related adverse events), with a comprehensive ophthalmic examination, retinal fundus photography, spectral-domain optical coherence tomography, and visual function tests to evaluate the stability or improvement of their visual performance. Results Of the 20 patients included in the analysis, all were of white race/ethnicity, 12 (60%) were male, and the mean (SD) age was 57.4 (11.6) years. Optical coherence tomography revealed the development of a fibrosislike hyperreflective tissue limited at the interface between the array and retina in 10 eyes (50%). In 9 of 10 patients (90%), fibrosis evolved and progressed to retinal schisis. Despite the development of the fibrosis and schisis, there was no deterioration in the patient's visual performance evaluated prospectively with visual function tests (square localization and direction of motion). Conclusions and Relevance Optical coherence tomography may be used to observe the retinal anatomic changes in patients with an Argus II Prothesis. This analysis revealed the development of a fibrosislike hyperreflective tissue limited at the interface between array and retina that progressed to retinal schisis but with no deterioration in the patients' visual performance.
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Affiliation(s)
- Stanislao Rizzo
- Azienda Ospedaliera Universitaria Careggi, Dipartimento di Medicina e Chirurgia Traslazionale, University of Florence, Florence, Italy
| | - Laura Cinelli
- Azienda Ospedaliera Universitaria Careggi, Dipartimento di Medicina e Chirurgia Traslazionale, University of Florence, Florence, Italy
| | - Lucia Finocchio
- Azienda Ospedaliera Universitaria Careggi, Dipartimento di Medicina e Chirurgia Traslazionale, University of Florence, Florence, Italy
| | - Ruggero Tartaro
- Azienda Ospedaliera Universitaria Careggi, Dipartimento di Medicina e Chirurgia Traslazionale, University of Florence, Florence, Italy
| | - Francesca Santoro
- Azienda Ospedaliera Universitaria Careggi, Dipartimento di Medicina e Chirurgia Traslazionale, University of Florence, Florence, Italy
| | - Ninel Z. Gregori
- Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami Miller School of Medicine, Miami, Florida
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45
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Spencer MJ, Kameneva T, Grayden DB, Meffin H, Burkitt AN. Global activity shaping strategies for a retinal implant. J Neural Eng 2019; 16:026008. [DOI: 10.1088/1741-2552/aaf071] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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46
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Seo KJ, Artoni P, Qiang Y, Zhong Y, Han X, Shi Z, Yao W, Fagiolini M, Fang H. Transparent, Flexible, Penetrating Microelectrode Arrays with Capabilities of Single-Unit Electrophysiology. ACTA ACUST UNITED AC 2019; 3:e1800276. [PMID: 32627399 DOI: 10.1002/adbi.201800276] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/08/2018] [Indexed: 01/08/2023]
Abstract
Accurately mapping neuronal activity across brain networks is critical to understand behaviors, yet it is very challenging due to the need of tools with both high spatial and temporal resolutions. Here, penetrating arrays of flexible microelectrodes made of low-impedance nanomeshes are presented, which are capable of recording single-unit electrophysiological neuronal activity and at the same time, transparent, allowing to bridge electrical and optical brain mapping modalities. These 32 transparent penetrating electrodes with site area, 225 µm2 , have a low impedance of ≈149 kΩ at 1 kHz, an adequate charge injection limit of ≈0.76 mC cm-2 , and up to 100% yield. Mechanical bending tests reveal that the array is robust up to 1000 bending cycles, and its high transmittance of 67% at 550 nm makes it suitable for combining with various optical methods. A temporary stiffening using polyethylene glycol allows the penetrating nanomesh arrays to be inserted into the brain minimally invasively, with in vivo validation of recordings of spontaneous and evoked single-unit activity of neurons across layers of the mouse visual cortex. Together, these results establish a novel neurotechnology-transparent, flexible, penetrating microelectrode arrays-which possesses great potential for brain research.
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Affiliation(s)
- Kyung Jin Seo
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Pietro Artoni
- Center for Life Science, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Yi Qiang
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Yiding Zhong
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Xun Han
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Zhan Shi
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Wenhao Yao
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA
| | - Michela Fagiolini
- Center for Life Science, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Hui Fang
- Department of Electrical and Computer Engineering, Northeastern University, Boston, MA, 02115, USA.,Department of Bioengineering, Northeastern University, Boston, MA, 02115, USA.,Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, USA
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Niketeghad S, Pouratian N. Brain Machine Interfaces for Vision Restoration: The Current State of Cortical Visual Prosthetics. Neurotherapeutics 2019; 16:134-143. [PMID: 30194614 PMCID: PMC6361050 DOI: 10.1007/s13311-018-0660-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Loss of vision alters the day to day life of blind individuals and may impose a significant burden on their family and the economy. Cortical visual prosthetics have been shown to have the potential of restoring a useful degree of vision via stimulation of primary visual cortex. Due to current advances in electrode design and wireless power and data transmission, development of these prosthetics has gained momentum in the past few years and multiple sites around the world are currently developing and testing their designs. In this review, we briefly outline the visual prosthetic approaches and describe the history of cortical visual prosthetics. Next, we focus on the state of the art of cortical visual prosthesis by briefly explaining the design of current devices that are either under development or in the clinical testing phase. Lastly, we shed light on the challenges of each design and provide some potential solutions.
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Affiliation(s)
- Soroush Niketeghad
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA
| | - Nader Pouratian
- Department of Bioengineering, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Neurosurgery, University of California Los Angeles, Los Angeles, CA, USA.
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Koo B, Weiland J. Experimental factors effecting stability of Electrochemical Impedance Spectroscopy Measurements. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:2949-2952. [PMID: 30441018 DOI: 10.1109/embc.2018.8512973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Impedance measurement using Electrochemical Impedance Spectroscopy is a widely utilized technique in neural electrodes. Research and clinical devices that incorporate stimulating and recording microelectrodes routinely characterize the material's integrity and its functionality through impedance measurement. Nominal impedance values ensure a stable neural electrode-tissue contact capable of passing through power efficient electric signals with desired signal-tonoise ratio or effective volume coverage. However, the complexity of the in vivo environment limits the usage of the three-electrode setup, which has been accepted as the ideal method in providing a stable impedance measurement. Impedance data measured from microelectrodes in threeelectrode and two-electrode setups show that the two setups have similar outcomes in terms of the impedance modulus over a 0.5 Hz-100 kHz frequency range. Usage of a platinum counter electrode lowered the overall variance in impedance readings compared to the stainless steel counter electrode. However, correlation coefficient values $(>0.97)$ between three-electrode and two-electrode setups show that impedance values seldom deviate due to changes in electrode setup. Based on the results of this study, the usage of the two-electrode setup in vivo allowed acceptable electrochemical impedance spectroscopy accuracy, and the utilization of a platinum counter electrode is recommended to reduce measurement variance.
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Massachi J, Lo YK, Wang PM, Liu W. A Wireless Platform to Support Pre-Clinical Trial of Neural Implant for Spinal Cord Injury. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:5487-5490. [PMID: 30441579 DOI: 10.1109/embc.2018.8513636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The efficacy of many clinical applications of electrical stimulation is currently gauged only by patients' verbal feedback or through the use of an independent system, limiting physicians' ability to provide quality treatment. By integrating neural response recording into the system, though, more accurate measures of treatment effectiveness are possible. This paper presents a platform which enables wireless control of an implantable bioelectronic device which integrates functional electrical stimulation and simultaneous recording of neural activity for a wide range of potential applications including motor function prostheses for spinal cord injury, retinal prostheses, and treatments for various other conditions. The proposed wireless platform utilizes a mobile application to offer a user-friendly integrated interface that enables setup and execution of stimulation and collection of recording data in animal studies. This platform will also support the continuing development of closed-loop neuromodulation strategies for investigating potential therapies for various diseases.
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Trigui A, Hached S, Ammari AC, Savaria Y, Sawan M. Maximizing Data Transmission Rate for Implantable Devices Over a Single Inductive Link: Methodological Review. IEEE Rev Biomed Eng 2018; 12:72-87. [PMID: 30295628 DOI: 10.1109/rbme.2018.2873817] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Due to the constantly growing geriatric population and the projected increase of the prevalence of chronic diseases that are refractory to drugs, implantable medical devices (IMDs) such as neurostimulators, endoscopic capsules, artificial retinal prostheses, and brain-machine interfaces are being developed. According to many business forecast firms, the IMD market is expected to grow and they are subject to much research aiming to overcome the numerous challenges of their development. One of these challenges consists of designing a wireless power and data transmission system that has high power efficiency, high data rates, low power consumption, and high robustness against noise. This is in addition to minimal design and implementation complexity. This manuscript concerns a comprehensive survey of the latest techniques used to power up and communicate between an external base station and an IMD. Patient safety considerations related to biological, physical, electromagnetic, and electromagnetic interference concerns for wireless IMDs are also explored. The simultaneous powering and data communication techniques using a single inductive link for both power transfer and bidirectional data communication, including the various data modulation/demodulation techniques, are also reviewed. This review will hopefully contribute to the persistent efforts to implement compact reliable IMDs while lowering their cost and upsurging their benefits.
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