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Park R, Lee DH, Koh CS, Kwon YW, Chae SY, Kim CS, Jung HH, Jeong J, Hong SW. Laser-Assisted Structuring of Graphene Films with Biocompatible Liquid Crystal Polymer for Skin/Brain-Interfaced Electrodes. Adv Healthc Mater 2024; 13:e2301753. [PMID: 37820714 DOI: 10.1002/adhm.202301753] [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: 06/02/2023] [Revised: 10/09/2023] [Indexed: 10/13/2023]
Abstract
The work presented here introduces a facile strategy for the development of flexible and stretchable electrodes that harness the robust characteristics of carbon nanomaterials through laser processing techniques on a liquid crystal polymer (LCP) film. By utilizing LCP film as a biocompatible electronic substrate, control is demonstrated over the laser irradiation parameters to achieve efficient pattern generation and transfer printing processes, thereby yielding highly conductive laser-induced graphene (LIG) bioelectrodes. To enhance the resolution of the patterned LIG film, shadow masks are employed during laser scanning on the LCP film surface. This approach is compatible with surface-mounted device integration, enabling the circuit writing of LIG/LCP materials in a flexible format. Moreover, kirigami-inspired on-skin bioelectrodes are introduced that exhibit reasonable stretchability, enabling independent connections to healthcare hardware platforms for electrocardiogram (ECG) and electromyography (EMG) measurements. Additionally, a brain-interfaced LIG microelectrode array is proposed that combines mechanically compliant architectures with LCP encapsulation for stimulation and recording purposes, leveraging their advantageous structural features and superior electrochemical properties. This developed approach offers a cost-effective and scalable route for producing patterned arrays of laser-converted graphene as bioelectrodes. These bioelectrodes serve as ideal circuit-enabled flexible substrates with long-term reliability in the ionic environment of the human body.
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Affiliation(s)
- Rowoon Park
- Department of Optics and Mechatronics Engineering, Department of Cogno-Mechatronics Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan, 46241, Republic of Korea
| | - Dong Hyeon Lee
- School of Mechanical Engineering, Pusan National University, Busan, 46241, Republic of Korea
| | - Chin Su Koh
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul, 03722, Republic of Korea
| | - Young Woo Kwon
- Engineering Research Center for Color-Modulated Extra-Sensory Perception Technology, Pusan National University, Busan, 46241, Republic of Korea
| | - Seon Yeong Chae
- Engineering Research Center for Color-Modulated Extra-Sensory Perception Technology, Pusan National University, Busan, 46241, Republic of Korea
| | - Chang-Seok Kim
- Department of Optics and Mechatronics Engineering, Department of Cogno-Mechatronics Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan, 46241, Republic of Korea
- Engineering Research Center for Color-Modulated Extra-Sensory Perception Technology, Pusan National University, Busan, 46241, Republic of Korea
| | - Hyun Ho Jung
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul, 03722, Republic of Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, Department of Information Convergence Engineering, Pusan National University, Yangsan, 50612, Republic of Korea
| | - Suck Won Hong
- Department of Optics and Mechatronics Engineering, Department of Cogno-Mechatronics Engineering, College of Nanoscience and Nanotechnology, Pusan National University, Busan, 46241, Republic of Korea
- Engineering Research Center for Color-Modulated Extra-Sensory Perception Technology, Pusan National University, Busan, 46241, Republic of Korea
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Ahn SH, Koh CS, Park M, Jun SB, Chang JW, Kim SJ, Jung HH, Jeong J. Liquid Crystal Polymer-Based Miniaturized Fully Implantable Deep Brain Stimulator. Polymers (Basel) 2023; 15:4439. [PMID: 38006163 PMCID: PMC10675735 DOI: 10.3390/polym15224439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 10/22/2023] [Accepted: 10/27/2023] [Indexed: 11/26/2023] Open
Abstract
A significant challenge in improving the deep brain stimulation (DBS) system is the miniaturization of the device, aiming to integrate both the stimulator and the electrode into a compact unit with a wireless charging capability to reduce invasiveness. We present a miniaturized, fully implantable, and battery-free DBS system designed for rats, using a liquid crystal polymer (LCP), a biocompatible and long-term reliable material. The system integrates the simulator circuit, the receiver coil, and a 20 mm long depth-type microelectrode array in a dome-shaped LCP package that is 13 mm in diameter and 5 mm in height. Wireless powering and control via an inductive link enable device miniaturization, allowing for full implantation and, thus, the free behavior of untethered animals. The eight-channel stimulation electrode array was microfabricated on an LCP substrate to form a multilayered system substrate, which was monolithically encapsulated by a domed LCP lid using a specialized spot-welding process. The device functionality was validated via an in vivo animal experiment using a neuropathic pain model in rats. This experiment demonstrated an increase in the mechanical withdrawal threshold of the rats with microelectrical stimulation delivered using the fully implanted device, highlighting the effectiveness of the system.
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Affiliation(s)
- Seung-Hee Ahn
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Chin Su Koh
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Minkyung Park
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Sang Beom Jun
- Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul 03760, Republic of Korea
| | - Jin Woo Chang
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Hyun Ho Jung
- Department of Neurosurgery, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Joonsoo Jeong
- School of Biomedical Convergence Engineering, Pusan National University, Yangsan 50612, Republic of Korea
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Zhang Z, Yang X, Zhao Y, Ye F, Shang L. Liquid Crystal Materials for Biomedical Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2300220. [PMID: 37235719 DOI: 10.1002/adma.202300220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Revised: 04/04/2023] [Indexed: 05/28/2023]
Abstract
Liquid crystal is a state of matter being intermediate between solid and liquid. Liquid crystal materials exhibit both orientational order and fluidity. While liquid crystals have long been highly recognized in the display industry, in recent decades, liquid crystals provide new opportunities into the cross-field of material science and biomedicine due to their biocompatibility, multifunctionality, and responsiveness. In this review, the latest achievements of liquid crystal materials applied in biomedical fields are summarized. The start is made by introducing the basic concepts of liquid crystals, and then shifting to the components of liquid crystals as well as functional materials derived therefrom. After that, the ongoing and foreseeable applications of liquid crystal materials in the biomedical field with emphasis put on several cutting-edge aspects, including drug delivery, bioimaging, tissue engineering, implantable devices, biosensing, and wearable devices are discussed. It is hoped that this review will stimulate ingenious ideas for the future generation of liquid crystal-based drug development, artificial implants, disease diagnosis, health status monitoring, and beyond.
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Affiliation(s)
- Zhuohao Zhang
- Shanghai Xuhui Central Hospital, Zhongshan-Xuhui Hospital, and the Shanghai Key Laboratory of Medical Epigenetics, the International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Xinyuan Yang
- Shanghai Xuhui Central Hospital, Zhongshan-Xuhui Hospital, and the Shanghai Key Laboratory of Medical Epigenetics, the International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
| | - Yuanjin Zhao
- Shanghai Xuhui Central Hospital, Zhongshan-Xuhui Hospital, and the Shanghai Key Laboratory of Medical Epigenetics, the International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
- Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, School of Biological Science and Medical Engineering Southeast University, Nanjing, 210096, China
| | - Fangfu Ye
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang, 325001, China
| | - Luoran Shang
- Shanghai Xuhui Central Hospital, Zhongshan-Xuhui Hospital, and the Shanghai Key Laboratory of Medical Epigenetics, the International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, China
- Department of Rheumatology and Immunology, Nanjing Drum Tower Hospital, School of Biological Science and Medical Engineering Southeast University, Nanjing, 210096, China
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Lee T, Jeong H, Lee J, Seo JM, Baek C. Low dead space encapsulation and integration of circuits for retinal prosthesis based on cyclic olefin copolymer. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023; 2023:1-4. [PMID: 38083447 DOI: 10.1109/embc40787.2023.10341083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
A retinal prosthesis is a device that can provide artificial vision to people who have lost their sight from certain retinal disorder. Because the device needs to be inserted into the body, high flexibility and reliability is required. Recently, devices using thermoplastic polymers such as LCP and COC as substrates have been studied. Being a highly functional integrated device, retinal prosthesis poses many design challenges. Among them, the stimulation chip embedding can be a particularly important task. Although it is common to use a wire bonding method for chip embedding, there are several limitations that are difficult to apply to implantable device. In this investigation, a novel approach is developed for high spaceefficient electrical connections and perform reliable encapsulation of integrated circuits to replace wire bonding. Since designing and manufacturing the stimulator chip used in retinal prosthesis requires non-negligible cost, a silicon die with the identical shape was selected as a substitute for testing purposes.
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Choi GJ, Yoo HJ, Cho Y, Shim S, Yun S, Sung J, Lim Y, Jun SB, Kim SJ. Development of a miniaturized, reconnectable, and implantable multichannel connector. J Neural Eng 2022; 19. [PMID: 36228595 DOI: 10.1088/1741-2552/ac99ff] [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: 07/22/2022] [Accepted: 10/13/2022] [Indexed: 12/24/2022]
Abstract
Objective. Connectors for implantable neural prosthetic systems provide several advantages such as simplification of surgery, safe replacement of implanted devices, and modular design of the implant systems. With the rapid advancement of technologies for neural implants, miniaturized multichannel implantable connectors are also required. In this study, we propose a reconnectable and area-efficient multichannel implantable connector.Approach. A female-to-female adapter was fabricated using the thermal-press bonding of micropatterned liquid crystal polymer films. A bump inside the adapter enabled a reliable electrical connection by increasing the contact pressure between the contact pads of the adapter and the inserted cable. After connection, the adapter is enclosed in a metal case sealed with silicone elastomer packing. With different sizes of the packings, leakage current tests were performed under accelerated conditions to determine the optimal design for long-term reliability. Repeated connection tests were performed to verify the durability and reconnectability of the fabricated connector. The connector was implanted in rats, and the leakage currents were monitored to evaluate the stability of the connectorin vivo. Main results. The fabricated four- and eight-channel implantable connectors, assembled with the metal cases, had a diameter and length of 6 and 17 mm, respectively. Further, the contact resistances of the four- and eight-channel connectors were 53.2 and 75.2 mΩ, respectively. The electrical contact remained stable during repeated connection tests (50 times). The fabricated connectors with packings having 125%, 137%, and 150% volume ratios to the internal space of the metal case failed after 14, 88, and 14 d, respectively, in a 75 °C saline environment. In animal tests with rats, the connector maintained low leakage current levels for up to 92 d.Significance. An implantable and reconnectable multichannel connector was developed and evaluated. The feasibility of the proposed connector was evaluated in terms of electrical and mechanical characteristics as well as sealing performance. The proposed connector is expected to have potential applications in implantable neural prosthetic systems.
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Affiliation(s)
- Gwang Jin Choi
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Hyun Ji Yoo
- Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul, Republic of Korea
| | - YoonKyung Cho
- Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul, Republic of Korea
| | - Shinyong Shim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Seunghyeon Yun
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
| | - Jaehoon Sung
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, United States of America (On a leave of absence)
| | - Yoonseob Lim
- Center for Intelligent and Interactive Robotics, Korea Institute of Science and Technology, Seoul, Republic of Korea.,Department of HY-KIST Bio-convergence, Hanyang University, Seoul, Republic of Korea
| | - Sang Beom Jun
- Department of Electronic and Electrical Engineering, Ewha Womans University, Seoul, Republic of Korea.,Graduate Program in Smart Factory, Ewha Womans University, Seoul, Republic of Korea.,Division of Brain and Cognitive Sciences, Ewha Womans University, Seoul, Republic of Korea
| | - Sung June Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, Republic of Korea
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Mariello M, Kim K, Wu K, Lacour SP, Leterrier Y. Recent Advances in Encapsulation of Flexible Bioelectronic Implants: Materials, Technologies, and Characterization Methods. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2201129. [PMID: 35353928 DOI: 10.1002/adma.202201129] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/13/2022] [Indexed: 06/14/2023]
Abstract
Bioelectronic implantable systems (BIS) targeting biomedical and clinical research should combine long-term performance and biointegration in vivo. Here, recent advances in novel encapsulations to protect flexible versions of such systems from the surrounding biological environment are reviewed, focusing on material strategies and synthesis techniques. Considerable effort is put on thin-film encapsulation (TFE), and specifically organic-inorganic multilayer architectures as a flexible and conformal alternative to conventional rigid cans. TFE is in direct contact with the biological medium and thus must exhibit not only biocompatibility, inertness, and hermeticity but also mechanical robustness, conformability, and compatibility with the manufacturing of microfabricated devices. Quantitative characterization methods of the barrier and mechanical performance of the TFE are reviewed with a particular emphasis on water-vapor transmission rate through electrical, optical, or electrochemical principles. The integrability and functionalization of TFE into functional bioelectronic interfaces are also discussed. TFE represents a must-have component for the next-generation bioelectronic implants with diagnostic or therapeutic functions in human healthcare and precision medicine.
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Affiliation(s)
- Massimo Mariello
- Laboratory for Processing of Advanced Composites (LPAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
| | - Kyungjin Kim
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Electrical and MicroEngineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Kangling Wu
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Electrical and MicroEngineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Stéphanie P Lacour
- Bertarelli Foundation Chair in Neuroprosthetic Technology, Laboratory for Soft Bioelectronic Interfaces, Institute of Electrical and MicroEngineering, Institute of Bioengineering, Centre for Neuroprosthetics, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Yves Leterrier
- Laboratory for Processing of Advanced Composites (LPAC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, CH-1015, Switzerland
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Yun S, Koh CS, Seo J, Shim S, Park M, Jung HH, Eom K, Chang JW, Kim SJ. A Fully Implantable Miniaturized Liquid Crystal Polymer (LCP)-Based Spinal Cord Stimulator for Pain Control. SENSORS (BASEL, SWITZERLAND) 2022; 22:s22020501. [PMID: 35062462 PMCID: PMC8778878 DOI: 10.3390/s22020501] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 05/09/2023]
Abstract
Spinal cord stimulation is a therapy to treat the severe neuropathic pain by suppressing the pain signal via electrical stimulation of the spinal cord. The conventional metal packaged and battery-operated implantable pulse generator (IPG) produces electrical pulses to stimulate the spinal cord. Despite its stable operation after implantation, the implantation site is limited due to its bulky size and heavy weight. Wireless communications including wireless power charging is also restricted, which is mainly attributed to the electromagnetic shielding of the metal package. To overcome these limitations, here, we developed a fully implantable miniaturized spinal cord stimulator based on a biocompatible liquid crystal polymer (LCP). The fabrication of electrode arrays in the LCP substrate and monolithically encapsulating the circuitries using LCP packaging reduces the weight (0.4 g) and the size (the width, length, and thickness are 25.3, 9.3, and 1.9 mm, respectively). An inductive link was utilized to wirelessly transfer the power and the data to implanted circuitries to generate the stimulus pulse. Prior to implantation of the device, operation of the pulse generator was evaluated, and characteristics of stimulation electrode such as an electrochemical impedance spectroscopy (EIS) were measured. The LCP-based spinal cord stimulator was implanted into the spared nerve injury rat model. The degree of pain suppression upon spinal cord stimulation was assessed via the Von Frey test where the mechanical stimulation threshold was evaluated by monitoring the paw withdrawal responses. With no spinal cord stimulation, the mechanical stimulation threshold was observed as 1.47 ± 0.623 g, whereas the stimulation threshold was increased to 12.7 ± 4.00 g after spinal cord stimulation, confirming the efficacy of pain suppression via electrical stimulation of the spinal cord. This LCP-based spinal cord stimulator opens new avenues for the development of a miniaturized but still effective spinal cord stimulator.
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Affiliation(s)
- Seunghyeon Yun
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
| | - Chin Su Koh
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
| | - Jungmin Seo
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
| | - Shinyong Shim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
| | - Minkyung Park
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
| | - Hyun Ho Jung
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
| | - Kyungsik Eom
- Department of Electronics Engineering, College of Engineering, Pusan National University, Busan 46241, Korea
- Correspondence: (K.E.); (J.W.C.)
| | - Jin Woo Chang
- Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 03722, Korea; (C.S.K.); (M.P.); (H.H.J.)
- Correspondence: (K.E.); (J.W.C.)
| | - Sung June Kim
- Department of Electrical and Computer Engineering, College of Engineering, Seoul National University, Seoul 08826, Korea; (S.Y.); (J.S.); (S.S.); (S.J.K.)
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Shokur S, Mazzoni A, Schiavone G, Weber DJ, Micera S. A modular strategy for next-generation upper-limb sensory-motor neuroprostheses. MED 2021; 2:912-937. [DOI: 10.1016/j.medj.2021.05.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 04/28/2021] [Accepted: 05/10/2021] [Indexed: 02/06/2023]
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Mailhot N, Cheriton R, Vyas K, Cook J, Prawer S, Hinzer K, Spinello D. Eighty-Five Percent of Improved Optical Power Delivery to Epiretinal Prostheses Using Rigid Body Compensation Algorithm. J Biomech Eng 2021; 143:061009. [PMID: 33537711 DOI: 10.1115/1.4050026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Indexed: 11/08/2022]
Abstract
Vision impairment caused by degenerative retinal pathologies such as age-related macular degeneration can be treated using retinal implants. Such devices receive power and data using cables passing through a permanent surgical incision in the eye wall (sclera), which increases the risk to patients and surgical costs. A recently developed retinal implant design eliminates the necessity of the implant cable using a photonic power converter (PPC), which receives optical power and data through the pupil and is directed by an ellipsoidal reflector and micro-electromechanical mirror. We present a misalignment compensation algorithm model that accounts for rigid-body motions of the reflector relative to the eye and applies the correction to the mirror coordinates in the presence of angular misalignment of the reflector. We demonstrate that up to 85% of the nominal optical power can be delivered to the implant with axial reflector misalignments up to 30 deg using the compensation algorithm.
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Affiliation(s)
- Nathaniel Mailhot
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - Ross Cheriton
- National Research Council of Canada, Ottawa, ON K1N 6M6, Canada
| | - Kaustubh Vyas
- Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - John Cook
- Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - Steven Prawer
- Department of Physics, University of Melbourne, Melbourne VIC 3010, Australia
| | - Karin Hinzer
- Electrical Engineering and Computer Science, University of Ottawa, Ottawa, ON K1N 6M6, Canada
| | - Davide Spinello
- Department of Mechanical Engineering, University of Ottawa, Ottawa, ON K1N 6M6, Canada
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García-Estrada P, García-Bon MA, López-Naranjo EJ, Basaldúa-Pérez DN, Santos A, Navarro-Partida J. Polymeric Implants for the Treatment of Intraocular Eye Diseases: Trends in Biodegradable and Non-Biodegradable Materials. Pharmaceutics 2021; 13:701. [PMID: 34065798 PMCID: PMC8151640 DOI: 10.3390/pharmaceutics13050701] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/15/2022] Open
Abstract
Intraocular/Intravitreal implants constitute a relatively new method to treat eye diseases successfully due to the possibility of releasing drugs in a controlled and prolonged way. This particularity has made this kind of method preferred over other methods such as intravitreal injections or eye drops. However, there are some risks and complications associated with the use of eye implants, the body response being the most important. Therefore, material selection is a crucial factor to be considered for patient care since implant acceptance is closely related to the physical and chemical properties of the material from which the device is made. In this regard, there are two major categories of materials used in the development of eye implants: non-biodegradables and biodegradables. Although non-biodegradable implants are able to work as drug reservoirs, their surgical requirements make them uncomfortable and invasive for the patient and may put the eyeball at risk. Therefore, it would be expected that the human body responds better when treated with biodegradable implants due to their inherent nature and fewer surgical concerns. Thus, this review provides a summary and discussion of the most common non-biodegradable and biodegradable materials employed for the development of experimental and commercially available ocular delivery implants.
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Affiliation(s)
- Paulina García-Estrada
- Departamento de Ingenieria de Proyectos-CUCEI, Universidad de Guadalajara, C.P. 45157 Zapopan, Mexico; (P.G.-E.); (M.A.G.-B.); (E.J.L.-N.); (D.N.B.-P.)
| | - Miguel A. García-Bon
- Departamento de Ingenieria de Proyectos-CUCEI, Universidad de Guadalajara, C.P. 45157 Zapopan, Mexico; (P.G.-E.); (M.A.G.-B.); (E.J.L.-N.); (D.N.B.-P.)
| | - Edgar J. López-Naranjo
- Departamento de Ingenieria de Proyectos-CUCEI, Universidad de Guadalajara, C.P. 45157 Zapopan, Mexico; (P.G.-E.); (M.A.G.-B.); (E.J.L.-N.); (D.N.B.-P.)
| | - Dulce N. Basaldúa-Pérez
- Departamento de Ingenieria de Proyectos-CUCEI, Universidad de Guadalajara, C.P. 45157 Zapopan, Mexico; (P.G.-E.); (M.A.G.-B.); (E.J.L.-N.); (D.N.B.-P.)
| | - Arturo Santos
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, C.P. 45138 Zapopan, Mexico;
| | - Jose Navarro-Partida
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Campus Guadalajara, C.P. 45138 Zapopan, Mexico;
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Evaluation methods for long-term reliability of polymer-based implantable biomedical devices. Biomed Eng Lett 2021; 11:97-105. [PMID: 34150346 DOI: 10.1007/s13534-021-00188-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 03/24/2021] [Accepted: 04/05/2021] [Indexed: 01/04/2023] Open
Abstract
Long-term reliability of implantable biomedical devices is a critical issue for their practical usefulness and successful translation into clinical application. Reliability is particularly of great concern for recently demonstrated devices based on new materials typically relying on polymeric thin films and microfabrication process. While reliability testing protocol has been well-established for traditional metallic packages, common evaluation methods for polymer-based microdevices has yet to be agreed upon, even though various testing methods have been proposed. This article is aiming to summarize the evaluation methods on long-term reliability of emerging biomedical implants based on polymeric thin-films in terms of their theories and implementation with specific focus on difference from the traditional metallic packages.
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Chong H, Majerus SJ, Bogie KM, Zorman CA. Non‐hermetic packaging of biomedical microsystems from a materials perspective: A review. ACTA ACUST UNITED AC 2020. [DOI: 10.1002/mds3.10082] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Hao Chong
- Department of Electrical, Computer, and Systems Engineering Case Western Reserve University Cleveland OH USA
| | | | - Kath M. Bogie
- APT Center Louis Stokes VA Medical Center Cleveland OH USA
- Department of Orthopaedics Case Western Reserve University School of Medicine Cleveland OH USA
| | - Christian A. Zorman
- Department of Electrical, Computer, and Systems Engineering Case Western Reserve University Cleveland OH USA
- APT Center Louis Stokes VA Medical Center Cleveland OH USA
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Seo J, Yun S, Shim S, Cho SW, Choi JW, Kim JW, Kim SJ. Palatal implant system can provide effective treatment for obstructive sleep apnea by recovering retropalatal patency. J Neural Eng 2020; 17:026017. [DOI: 10.1088/1741-2552/ab7d61] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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14
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Choi GJ, Seo JM, Song YK, Kim SJ, Jang J, Kim S, Baek C, Yun S, Shim S, Seo J, Jung Y, Seo K. A Fully Implantable Wireless Stimulation System for Pigeon Navigation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:5310-5313. [PMID: 31947055 DOI: 10.1109/embc.2019.8857039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Navigation of freely moving animals has been studied for potential application to emergency situations and hazardous environments. A fully implantable stimulation system for remote animal navigation was proposed and applied to living pigeons. The animal navigation system, consisting of an external controller and a neural stimulator, was designed based on the anatomy of the pigeons. Depth electrodes were fabricated based on the anatomy of target pigeon brain regions. The fabricated neural stimulators received data wirelessly from the external controller and generated biphasic current pulses with preset parameters of amplitude, duration, and rate. The average impedance of the fabricated electrodes was 12.0∠-13.05° kΩ at 1 kHz. The neural stimulator was implanted on the dorsal side, and the depth electrodes were inserted into the formatio reticularis medialis mesencephali (FRM). When successive current pulses with an amplitude of 400 μA, a rate of 58 Hz, and a duration of 80 μs were applied to the target regions at 0.85 s intervals, turning/circling behaviors were induced for 6.2 s. The feasibility of the proposed wireless stimulation system was demonstrated in vivo.
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Shim S, Kim SJ. A Feasibility Study on Optically Transparent Encapsulation for Implantable Neural Prostheses. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2019:3754-3757. [PMID: 31946691 DOI: 10.1109/embc.2019.8857602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Optically transparent encapsulation is presented with results from long-term reliability and light transmission tests. This technology is required in certain implantable neural prostheses that demand the transmission of optical signals through an encapsulating material, such as in retinal implants or in optogenetic applications. In this study, biocompatible film-type cyclic olefin polymers (COPs) with low moisture absorption (<; 0.01 %) and high light transmission (92 %) are utilized as encapsulating materials based on thermal lamination. The reliability of COP encapsulation is characterized through accelerated soak tests in a 75 °C saline solution to measure the leakage currents from encapsulated inter-digitated electrodes. These tests had been done for 211 days with the estimated lifetime of 8.05 years at 37 °C. In addition, the optical properties of a thermally laminated COP film sample in relation to its thickness are evaluated by an experimental setup which uses projected line patterns on an image sensor. The light transmittance of COP film samples thinner than 376 μm exceeded 91.69 %, and the minimum distinguishable line pitch was 47.6 μm at a thickness of 26 μm. These results validate the feasibility of optically transparent encapsulation using COPs and may contribute to its use in future implantable neural prostheses.
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Implantable electrical stimulation bioreactor with liquid crystal polymer-based electrodes for enhanced bone regeneration at mandibular large defects in rabbit. Med Biol Eng Comput 2019; 58:383-399. [PMID: 31853774 DOI: 10.1007/s11517-019-02046-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 09/05/2019] [Indexed: 02/07/2023]
Abstract
The osseous regeneration of large bone defects is still a major clinical challenge in maxillofacial and orthopedic surgery. Previous studies demonstrated that biphasic electrical stimulation (ES) stimulates bone formation; however, polyimide electrode should be removed after regeneration. This study presents an implantable electrical stimulation bioreactor with electrodes based on liquid crystal polymer (LCP), which can be permanently implanted due to excellent biocompatibility to bone tissue. The bioreactor was implanted into a critical-sized bone defect and subjected to ES for one week, where bone regeneration was evaluated four weeks after surgery using micro-CT. The effect of ES via the bioreactor was compared with a sham control group and a positive control group that received recombinant human bone morphogenetic protein (rhBMP)-2 (20 μg). New bone volume per tissue volume (BV/TV) in the ES and rhBMP-2 groups increased to 132% (p < 0.05) and 174% (p < 0.01), respectively, compared to that in the sham control group. In the histological evaluation, there was no inflammation within the bone defects and adjacent to LCP in all the groups. This study showed that the ES bioreactor with LCP electrodes could enhance bone regeneration at large bone defects, where LCP can act as a mechanically resistant outer box without inflammation. Graphical abstract To enhance bone regeneration, a bioreactor comprising collagen sponge and liquid crystal polymer-based electrode was implanted in the bone defect. Within the defect, electrical current pulses having biphasic waveform were applied from the implanted bioreactor.
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Choi GJ, Jang J, Kang S, Shim S, Baek C, Kim B, Park Y, Kim S, Jung Y, Seo K, Seo JM, Song YK, Kim SJ. Locomotion Control of Pigeons using Polymer-based Deep Brain Electrodes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:1871-1874. [PMID: 30440761 DOI: 10.1109/embc.2018.8512684] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This paper describes the electrical modulation of locomotion in pigeons using deep brain electrodes. Polymer-based depth electrodes with four channels were fabricated. Based on the location of the nucleus intercollicularis (ICo), the shanks of the depth electrodes were designed to be a length of 11 mm. After the implantation of the depth electrode into the ICo region of the brain, it was connected by wires to a custom-made stimulator, and biphasic current pulses were delivered. Current pulses with an amplitude of 0.5 mA, a rate of 58.0 Hz, and a duration of $320\mu \mathrm{s} $s were applied for 0.5 s. When the ICo region was electrically stimulated, taking-off behavior was successfully induced for 0.4 s. Induction of taking-off behavior by electrical stimulation, when coupled to control of turning and running forward locomotions, may contribute to the development of remote flight-control system of freely moving pigeon.
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Seo J, Kim JW, Cho SW, Shim S, Choi JW, Kim SJ. Preliminary Study of Palatal Implant for Sleep Apnea Control. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2019; 2018:1498-1501. [PMID: 30440676 DOI: 10.1109/embc.2018.8512463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A fully-implantable device for treating obstructive sleep apnea (OSA) is conceptually suggested using soft palate stimulation. In this research, two in vivo studies were conducted to demonstrate electrical and physical feasibilities of the suggested device. First, electrical stimulation was delivered to the soft palate of a rabbit using a stimulator ASIC. The stimulation frequencies were swept from 20 Hz to 200 Hz to find out the appropriate parameter. Also, threshold level of the current pulse was evaluated to be 1.10 mA with an observance of a C-arm fluoroscopy. Second, a mock-up was fabricated with liquid crystal polymer (LCP), reflecting dimensions of the suggested device. The mock-up was inserted toward the soft palate of a rabbit by incising the hard palate in a lateral direction. After the mock-up was inserted, protrusion of the device was not detected and the subject stayed alive for at least a month at the time of this writing. Finally, several discussions on the palatal implant fabrication with LCP are presented.
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Recent Progress in Wireless Sensors for Wearable Electronics. SENSORS 2019; 19:s19204353. [PMID: 31600870 PMCID: PMC6848938 DOI: 10.3390/s19204353] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 09/30/2019] [Accepted: 10/01/2019] [Indexed: 02/06/2023]
Abstract
The development of wearable electronics has emphasized user-comfort, convenience, security, and improved medical functionality. Several previous research studies transformed various types of sensors into a wearable form to more closely monitor body signals and enable real-time, continuous sensing. In order to realize these wearable sensing platforms, it is essential to integrate wireless power supplies and data communication systems with the wearable sensors. This review article discusses recent progress in wireless technologies and various types of wearable sensors. Also, state-of-the-art research related to the application of wearable sensor systems with wireless functionality is discussed, including electronic skin, smart contact lenses, neural interfaces, and retinal prostheses. Current challenges and prospects of wireless sensor systems are discussed.
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Au SLC, Chen FYB, Budgett DM, Malpas SC, Guild SJ, McCormick D. Injection Molded Liquid Crystal Polymer Package for Chronic Active Implantable Devices With Application to an Optogenetic Stimulator. IEEE Trans Biomed Eng 2019; 67:1357-1365. [PMID: 31442965 DOI: 10.1109/tbme.2019.2936577] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Implanted electronics require protection from the body's fluids to avoid moisture induced failure. This study presents an injection molded liquid crystal polymer (LCP) package to protect active implantable devices for chronic applications, such as in optogenetic research. The technology is applied and assessed through a custom package for a fully implantable optogenetic stimulation system, built on a versatile telemetry system that can incorporate additional stimulating and recording channels. An adapted quasi-steady state model predicts the lifetime of an enclosure, where the definition of the lifetime is the time before the internal relative humidity (RH) reaches a time constant, or 63%RH, a conservative limit to minimize the risk of corrosion. The lifetime of the LCP optogenetic device is 94 days, and can be extended to 326 days with the inclusion of 5% w/v silica gel desiccant. Samples of the LCP optogenetic device containing humidity sensors testing in saline at 38 °C support the RH change predictions. Desiccants inside the implant enclosure can store permeating moisture and prolong the life expectancy of LCP-based implants to years or decades. The results of this study demonstrates the feasibility of providing reliable protection for chronic optogenetic implants, and the technology can be transferred to other applications as an easily-manufactured, cost-effective, radiofrequency compatible alternative to hermetic packaging for chronic studies.
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Ahn SH, Jeong J, Kim SJ. Emerging Encapsulation Technologies for Long-Term Reliability of Microfabricated Implantable Devices. MICROMACHINES 2019; 10:E508. [PMID: 31370259 PMCID: PMC6723304 DOI: 10.3390/mi10080508] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/20/2019] [Accepted: 07/29/2019] [Indexed: 01/11/2023]
Abstract
The development of reliable long-term encapsulation technologies for implantable biomedical devices is of paramount importance for the safe and stable operation of implants in the body over a period of several decades. Conventional technologies based on titanium or ceramic packaging, however, are not suitable for encapsulating microfabricated devices due to their limited scalability, incompatibility with microfabrication processes, and difficulties with miniaturization. A variety of emerging materials have been proposed for encapsulation of microfabricated implants, including thin-film inorganic coatings of Al2O3, HfO2, SiO2, SiC, and diamond, as well as organic polymers of polyimide, parylene, liquid crystal polymer, silicone elastomer, SU-8, and cyclic olefin copolymer. While none of these materials have yet been proven to be as hermetic as conventional metal packages nor widely used in regulatory approved devices for chronic implantation, a number of studies have demonstrated promising outcomes on their long-term encapsulation performance through a multitude of fabrication and testing methodologies. The present review article aims to provide a comprehensive, up-to-date overview of the long-term encapsulation performance of these emerging materials with a specific focus on publications that have quantitatively estimated the lifetime of encapsulation technologies in aqueous environments.
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Affiliation(s)
- Seung-Hee Ahn
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea
| | - Joonsoo Jeong
- Department of Biomedical Engineering, School of Medicine, Pusan National University, Yangsan 50612, Korea.
| | - Sung June Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea.
- Institute of Aging, College of Medicine, Seoul National University, Seoul 08826, Korea.
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Remote-Controlled Fully Implantable Neural Stimulator for Freely Moving Small Animal. ELECTRONICS 2019. [DOI: 10.3390/electronics8060706] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The application of a neural stimulator to small animals is highly desired for the investigation of electrophysiological studies and development of neuroprosthetic devices. For this purpose, it is essential for the device to be implemented with the capabilities of full implantation and wireless control. Here, we present a fully implantable stimulator with remote controllability, compact size, and minimal power consumption. Our stimulator consists of modular units of (1) a surface-type cortical array for inducing directional change of a rat, (2) a depth-type array for providing rewards, and (3) a package for accommodating the stimulating electronics, a battery and ZigBee telemetry, all of which are assembled after independent fabrication and implantation using customized flat cables and connectors. All three modules were packaged using liquid crystal polymer (LCP) to avoid any chemical reaction after implantation. After bench-top evaluation of device functionality, the stimulator was implanted into rats to train the animals to turn to the left (or right) following a directional cue applied to the barrel cortex. Functionality of the device was also demonstrated in a three-dimensional (3D) maze structure, by guiding the rats to better navigate in the maze. The movement of the rat could be wirelessly controlled by a combination of artificial sensation evoked by the surface electrode array and reward stimulation. We could induce rats to turn left or right in free space and help their navigation through the maze. The polymeric packaging and modular design could encapsulate the devices with strict size limitations, which made it possible to fully implant the device into rats. Power consumption was minimized by a dual-mode power-saving scheme with duty cycling. The present study demonstrated feasibility of the proposed neural stimulator to be applied to neuroprosthesis research.
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Zeng Q, Zhao S, Yang H, Zhang Y, Wu T. Micro/Nano Technologies for High-Density Retinal Implant. MICROMACHINES 2019; 10:E419. [PMID: 31234507 PMCID: PMC6630275 DOI: 10.3390/mi10060419] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 01/10/2023]
Abstract
During the past decades, there have been leaps in the development of micro/nano retinal implant technologies, which is one of the emerging applications in neural interfaces to restore vision. However, higher feedthroughs within a limited space are needed for more complex electronic systems and precise neural modulations. Active implantable medical electronics are required to have good electrical and mechanical properties, such as being small, light, and biocompatible, and with low power consumption and minimal immunological reactions during long-term implantation. For this purpose, high-density implantable packaging and flexible microelectrode arrays (fMEAs) as well as high-performance coating materials for retinal stimulation are crucial to achieve high resolution. In this review, we mainly focus on the considerations of the high-feedthrough encapsulation of implantable biomedical components to prolong working life, and fMEAs for different implant sites to deliver electrical stimulation to targeted retinal neuron cells. In addition, the functional electrode materials to achieve superior stimulation efficiency are also reviewed. The existing challenge and future research directions of micro/nano technologies for retinal implant are briefly discussed at the end of the review.
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Affiliation(s)
- Qi Zeng
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| | - Saisai Zhao
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| | - Hangao Yang
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
| | - Yi Zhang
- Shenzhen CAS-Envision Medical Technology Co. Ltd., Shenzhen 518100, China.
| | - Tianzhun Wu
- Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, China.
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Kim C, Jeong J, Kim SJ. Recent Progress on Non-Conventional Microfabricated Probes for the Chronic Recording of Cortical Neural Activity. SENSORS (BASEL, SWITZERLAND) 2019; 19:E1069. [PMID: 30832357 PMCID: PMC6427797 DOI: 10.3390/s19051069] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 02/06/2023]
Abstract
Microfabrication technology for cortical interfaces has advanced rapidly over the past few decades for electrophysiological studies and neuroprosthetic devices offering the precise recording and stimulation of neural activity in the cortex. While various cortical microelectrode arrays have been extensively and successfully demonstrated in animal and clinical studies, there remains room for further improvement of the probe structure, materials, and fabrication technology, particularly for high-fidelity recording in chronic implantation. A variety of non-conventional probes featuring unique characteristics in their designs, materials and fabrication methods have been proposed to address the limitations of the conventional standard shank-type ("Utah-" or "Michigan-" type) devices. Such non-conventional probes include multi-sided arrays to avoid shielding and increase recording volumes, mesh- or thread-like arrays for minimized glial scarring and immune response, tube-type or cylindrical probes for three-dimensional (3D) recording and multi-modality, folded arrays for high conformability and 3D recording, self-softening or self-deployable probes for minimized tissue damage and extensions of the recording sites beyond gliosis, nanostructured probes to reduce the immune response, and cone-shaped electrodes for promoting tissue ingrowth and long-term recording stability. Herein, the recent progress with reference to the many different types of non-conventional arrays is reviewed while highlighting the challenges to be addressed and the microfabrication techniques necessary to implement such features.
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Affiliation(s)
- Chaebin Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea.
| | - Joonsoo Jeong
- Department of Biomedical Engineering, School of Medicine, Pusan National University, Yangsan 50612, Korea.
| | - Sung June Kim
- Department of Electrical and Computer Engineering, Seoul National University, Seoul 08826, Korea.
- Institute on Aging, College of Medicine, Seoul National University, Seoul 08826, Korea.
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Bae SH, Jeong J, Kim SJ, Chung H, Seo JM. Investigation of Surgical Techniques for Optimization of Long-Term Outcomes of LCP-Based Retinal Prosthesis Implantation. Transl Vis Sci Technol 2018; 7:17. [PMID: 30159210 PMCID: PMC6108533 DOI: 10.1167/tvst.7.4.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/02/2018] [Indexed: 01/09/2023] Open
Abstract
Purpose To investigate reproducible surgical techniques to optimize the long-term safety of liquid crystal polymer (LCP)-based retinal prosthesis implantation. Methods An LCP-based retinal prosthesis is fabricated monolithically on a single-body LCP substrate with all components, including the package and electrode array. We implanted the electrode array into the suprachoroidal space and anchored the package and transition part to the sclera in rabbits (n = 11). The safety profile was assessed upon the completion of the surgery and postoperatively. Results The surgical procedures for implantation of the entire system were easily performed in nine eyes (81.8%) without any intraoperative complications. In the other two eyes (18.2%), surgical complications related to electrode insertion, including optic nerve damage and retinal tear, arose. In 10 eyes (90.9%), the devices were well tolerated for at least 3 months. However, in most eyes (nine; 81.8%), two complications began to appear after 3 months, postoperatively, including conjunctival erosion or dehiscence over the package or transition part. The electrode arrays were maintained safely in the suprachoroidal space after surgery without any complications, regardless of the status of the extraocular components in all cases except two intraoperative complications. Conclusions We established safe and reproducible surgical techniques for implantation of our LCP-based retinal prosthesis into the suprachoroidal space. Although issues related to surgical technique or device configuration were identified, further technical solutions would improve the long-term safety of device implantation. Translational Relevance This study presents successful implantation of LCP-based retinal prosthesis. The technical solutions will permit an optimization of surgical techniques.
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Affiliation(s)
- So Hyun Bae
- Department of Ophthalmology, Kangnam Sacred Heart Hospital, College of Medicine, Hallym University, Seoul, Republic of Korea.,Interdisciplinary Program for Bioengineering, Seoul National University, Seoul, Republic of Korea
| | - Joonsoo Jeong
- School of Engineering, Brown University, Providence, RI, USA
| | - Sung June Kim
- Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Institute of Engineering Research, Seoul National University, Seoul, Republic of Korea
| | - Hum Chung
- Department of Ophthalmology, Chung-Ang University Hospital, Seoul, Republic of Korea
| | - Jong-Mo Seo
- Interdisciplinary Program for Bioengineering, Seoul National University, Seoul, Republic of Korea.,Department of Electrical and Computer Engineering, Inter-University Semiconductor Research Center, Institute of Engineering Research, Seoul National University, Seoul, Republic of Korea.,Department of Ophthalmology, Biomedical Research Institute, Seoul National University Hospital, Seoul, Republic of Korea
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Shepherd RK, Villalobos J, Burns O, Nayagam DAX. The development of neural stimulators: a review of preclinical safety and efficacy studies. J Neural Eng 2018; 15:041004. [PMID: 29756600 PMCID: PMC6049833 DOI: 10.1088/1741-2552/aac43c] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Given the rapid expansion of the field of neural stimulation and the rigorous regulatory approval requirements required before these devices can be applied clinically, it is important that there is clarity around conducting preclinical safety and efficacy studies required for the development of this technology. APPROACH The present review examines basic design principles associated with the development of a safe neural stimulator and describes the suite of preclinical safety studies that need to be considered when taking a device to clinical trial. MAIN RESULTS Neural stimulators are active implantable devices that provide therapeutic intervention, sensory feedback or improved motor control via electrical stimulation of neural or neuro-muscular tissue in response to trauma or disease. Because of their complexity, regulatory bodies classify these devices in the highest risk category (Class III), and they are therefore required to go through a rigorous regulatory approval process before progressing to market. The successful development of these devices is achieved through close collaboration across disciplines including engineers, scientists and a surgical/clinical team, and the adherence to clear design principles. Preclinical studies form one of several key components in the development pathway from concept to product release of neural stimulators. Importantly, these studies provide iterative feedback in order to optimise the final design of the device. Key components of any preclinical evaluation include: in vitro studies that are focussed on device reliability and include accelerated testing under highly controlled environments; in vivo studies using animal models of the disease or injury in order to assess efficacy and, given an appropriate animal model, the safety of the technology under both passive and electrically active conditions; and human cadaver and ex vivo studies designed to ensure the device's form factor conforms to human anatomy, to optimise the surgical approach and to develop any specialist surgical tooling required. SIGNIFICANCE The pipeline from concept to commercialisation of these devices is long and expensive; careful attention to both device design and its preclinical evaluation will have significant impact on the duration and cost associated with taking a device through to commercialisation. Carefully controlled in vitro and in vivo studies together with ex vivo and human cadaver trials are key components of a thorough preclinical evaluation of any new neural stimulator.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, East Melbourne, Australia. Medical Bionics Department, University of Melbourne, Melbourne, Australia
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Bareket L, Barriga-Rivera A, Zapf MP, Lovell NH, Suaning GJ. Progress in artificial vision through suprachoroidal retinal implants. J Neural Eng 2018; 14:045002. [PMID: 28541930 DOI: 10.1088/1741-2552/aa6cbb] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Retinal implants have proven their ability to restore visual sensation to people with degenerative retinopathy, characterized by photoreceptor cell death and the retina's inability to sense light. Retinal bionics operate by electrically stimulating the surviving neurons in the retina, thus triggering the transfer of visual sensory information to the brain. Suprachoroidal implants were first investigated in Australia in the 1950s. In this approach, the neuromodulation hardware is positioned between the sclera and the choroid, thus providing significant surgical and safety benefits for patients, with the potential to maintain residual vision combined with the artificial input from the device. Here we review the latest advances and state of the art devices for suprachoroidal prostheses, highlight future technologies and discuss challenges and perspectives towards improved rehabilitation of vision.
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Affiliation(s)
- Lilach Bareket
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
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Dong W, Wang Y, Zhou Y, Bai Y, Ju Z, Guo J, Gu G, Bai K, Ouyang G, Chen S, Zhang Q, Huang Y. Soft human–machine interfaces: design, sensing and stimulation. INTERNATIONAL JOURNAL OF INTELLIGENT ROBOTICS AND APPLICATIONS 2018. [DOI: 10.1007/s41315-018-0060-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Plateau-Shaped Flexible Polymer Microelectrode Array for Neural Recording. Polymers (Basel) 2017; 9:polym9120690. [PMID: 30965988 PMCID: PMC6418796 DOI: 10.3390/polym9120690] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/04/2017] [Accepted: 12/05/2017] [Indexed: 11/30/2022] Open
Abstract
Conventional polymer multielectrode arrays (MEAs) have limitations resulting from a high Young’s modulus, including low conformability and gaps between the electrodes and neurons. These gaps are not a problem in soft tissues such as the brain, due to the repopulation phenomenon. However, gaps can result in signal degradation when recording from a fiber bundle, such as the spinal cord. Methods: We propose a method for fabricating flexible polydimethylsiloxane (PDMS)-based MEAs featuring plateau-shaped microelectrodes. The proposed fabrication technique enables the electrodes on the surface of MEAs to make a tight connection to the neurons, because the wire of the MEA is fabricated to be plateau-shaped, as the Young’s modulus of PDMS is similar to soft tissues and PDMS follows the curvature of the neural tissue due to its high conformability compared to the other polymers. Injury caused by the movement of the MEAs can therefore be minimized. Each electrode has a diameter of 130 μm and the 8-channel array has a center-to-center electrode spacing of 300 μm. The signal-to-noise ratio of the plateau-shaped electrodes was larger than that of recessed electrodes because there was no space between the electrode and neural cell. Reliable neural recordings were possible by adjusting the position of the electrode during the experiment without trapping air under the electrodes. Simultaneous multi-channel neural recordings were successfully achieved from the spinal cord of rodents. We describe the fabrication technique, electrode 3D profile, electrode impedance, and MEA performance in in vivo experiments in rodents.
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Barriga-Rivera A, Tatarinoff V, Lovell NH, Morley JW, Suaning GJ. Long-term anesthetic protocol in rats: feasibility in electrophysiology studies in visual prosthesis. Vet Ophthalmol 2017; 21:290-297. [PMID: 29148158 DOI: 10.1111/vop.12507] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Electrical stimulation of excitable cells provides therapeutic benefits for a variety of medical conditions, including restoration of partial vision to those blinded via some types of retinal degeneration. To improve visual percepts elicited by the current technology, researchers are conducting acute electrophysiology experiments, mainly in cats. However, the rat can provide a model of a range of retinal diseases and possesses a sufficiently large eye to be used in this field. This article presents a long-term anesthetic protocol to enable electrophysiology experiments to further the development of visual prostheses. Six Long-Evans rats (aged between 14 and 16 weeks) were included in this study. Surgical anesthesia was maintained for more than 15 h by combining constant intravenous infusion of ketamine (24.0-34.5 mg/kg/h), xylazine (0.9-1.2 mg/kg/h), and inhaled isoflurane in oxygen (<0.5%). Overall heart rate, respiratory rate, and body temperature remained between 187-233 beats/min, 45-58 breaths/min, and 36-38 °C, respectively. Neural responses to 200-ms light pulses were recorded from the superior colliculus using a 32-channel neural probe at the beginning and before termination of the experiment. Robust responses were recorded from distinct functional types of retinal pathways. In addition, a platinum electrode was implanted in the retrobulbar space. The retina was electrically stimulated, and the activation threshold was determined to be 5.24 ± 0.24 μC/cm2 . This protocol may be used not only in the field of visual prosthesis research, but in other research areas requiring longer term acute experiments.
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Affiliation(s)
- Alejandro Barriga-Rivera
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia.,Division of Neuroscience, University Pablo de Olavide, Sevilla, 41013, Spain
| | - Veronica Tatarinoff
- Sydney Imaging Core Research Facility, The University of Sydney, NSW, 2006, Australia
| | - Nigel H Lovell
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW, 2052, Australia
| | - John W Morley
- School of Medicine, The University of Western Sydney, Sydney, NSW, Australia.,School of Medical Science, UNSW, Sydney, NSW, 2052, Australia
| | - Gregg J Suaning
- Sydney Medical School, The University of Sydney, NSW, 2006, Australia.,Faculty of Engineering and Information Technologies, The University of Sydney, NSW, 2006, Australia
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Seo J, Choi GJ, Park S, Lee J, Baek C, Jang J, Lim J, Shin S, Seo K, Seo JM, Song YK, Kim SJ. Wireless navigation of pigeons using polymer-based fully implantable stimulator: A pilot study using depth electrodes. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:917-920. [PMID: 29060022 DOI: 10.1109/embc.2017.8036974] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A polymer-based implantable stimulator for wirelessly navigating pigeons was conceptually suggested and a pilot study using depth electrodes was conducted. In this study, depth electrodes based on liquid crystal polymer (LCP) with eight channels were designed and fabricated. Electrochemical impedance spectrum (EIS) assessments were performed to measure impedances of the electrodes. The average value of the measured impedances was 16.8∠15.8 ° kμ. The electrodes were then advanced to a target nucleus (formatio reticularis medialis mesencephalic, FRM) of a pigeon to prove their in vivo feasibilities. Biphasic current pulses were generated by a custom-made stimulator and delivered to the electrodes to stimulate the FRM electrically. Pulses with an amplitude level of 0.567 μA, a rate of 58.0 Hz, and a duration of 1.00 ms were applied with inter-stimulus intervals of three minutes. Turning and circling behaviors were consistently shown when the FRM was stimulated. The feasibilities of the electrodes were proved in both in vitro and in vivo tests, as a pilot study for the suggested scheme. Finally, several discussions of the assessments and extensions for a fully implantable stimulator were described.
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Cheng DL, Greenberg PB, Borton DA. Advances in Retinal Prosthetic Research: A Systematic Review of Engineering and Clinical Characteristics of Current Prosthetic Initiatives. Curr Eye Res 2017; 42:334-347. [PMID: 28362177 DOI: 10.1080/02713683.2016.1270326] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE To date, reviews of retinal prostheses have focused primarily on devices undergoing human trials in the Western Hemisphere and fail to capture significant advances in materials and engineering research in countries such as Japan and Korea, as well as projects in early stages of development. To address these gaps, this systematic review examines worldwide advances in retinal prosthetic research, evaluates engineering characteristics and clinical progress of contemporary device initiatives, and identifies potential directions for future research in the field of retinal prosthetics. METHODS A literature search using PubMed, Google Scholar, and IEEExplore was conducted following the PRISMA Guidelines for Systematic Review. Inclusion criteria were peer-reviewed papers demonstrating progress in human or animal trials and papers discussing the prosthetic engineering design. For each initiative, a description of the device, its engineering considerations, and recent clinical results were provided. RESULTS Ten prosthetic initiatives met our inclusion criteria and were organized by stimulation location. Of these initiatives, four have recently completed human trials, three are undergoing multi- or single-center human trials, and three are undergoing preclinical animal testing. Only the Argus II (FDA 2013, CE 2011) has obtained FDA approval for use in the United States; the Alpha-IMS (CE 2013) has achieved the highest visual acuity using a Landolt-C test to date and is the only device presently undergoing a multicenter clinical trial. CONCLUSION Several distinct approaches to retinal stimulation have been successful in eliciting visual precepts in animals and/or humans. However, many clinical needs are still not met and engineering challenges must be addressed before a retinal prosthesis with the capability to fully and safely restore functional vision can be realized.
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Affiliation(s)
- Derrick L Cheng
- a Alpert Medical School , Brown University , Providence , RI , USA
| | - Paul B Greenberg
- b Section of Ophthalmology , Providence VA Medical Center , Providence , RI , USA.,c Division of Ophthalmology, Alpert Medical School , Brown University , Providence , RI , USA
| | - David A Borton
- d School of Engineering , Brown University , Providence , RI , USA.,e Brown Institute for Brain Science , Brown University , Providence , RI , USA
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Novel four-sided neural probe fabricated by a thermal lamination process of polymer films. J Neurosci Methods 2017; 278:25-35. [DOI: 10.1016/j.jneumeth.2016.12.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 12/22/2016] [Accepted: 12/23/2016] [Indexed: 02/02/2023]
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Seo J, Wee JH, Park JH, Park P, Kim JW, Kim SJ. Nerve cuff electrode using embedded magnets and its application to hypoglossal nerve stimulation. J Neural Eng 2016; 13:066014. [DOI: 10.1088/1741-2560/13/6/066014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ha S, Khraiche ML, Akinin A, Jing Y, Damle S, Kuang Y, Bauchner S, Lo YH, Freeman WR, Silva GA, Cauwenberghs G. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry. J Neural Eng 2016; 13:056008. [PMID: 27529371 DOI: 10.1088/1741-2560/13/5/056008] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. APPROACH The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. MAIN RESULTS A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. SIGNIFICANCE Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.
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Affiliation(s)
- Sohmyung Ha
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, 92093 USA. Institute of Engineering in Medicine, University of California, San Diego, La Jolla, CA, 92093 USA
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Jeong J, Hyun Bae S, Seo JM, Chung H, June Kim S. Long-term evaluation of a liquid crystal polymer (LCP)-based retinal prosthesis. J Neural Eng 2016; 13:025004. [PMID: 26905477 DOI: 10.1088/1741-2560/13/2/025004] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The aim of this study is to evaluate the long-term reliability of a recently presented liquid crystal polymer (LCP) -based retinal prosthesis in vitro as well as in vivo. Because an all-polymer implant introduces another intrinsic leak type due to gas permeation, for which the traditional helium leak test for metallic packages was not designed to quantify, a new method to investigate its durability is required. APPROACH We designed and carried out a series of reliability tests specifically for all-polymer implants by quantitatively investigating moisture ingress through various pathways of the polymer surface, and the polymer-polymer and polymer-metal adhesions. Moisture permeation through the bulk material was estimated by analytic calculation, while water ingress through the adhesively sealed LCP-LCP and LCP-metal interfaces was investigated using the separate parts of an electrode array and a package in an accelerated aging condition. In vivo tests were done in rabbits to examine the long-term biocompatibility and implantation stability by fundus observation and optical coherence tomography (OCT) imaging. MAIN RESULTS The analytic calculation estimated good barrier properties of the LCP. Samples of the LCP-based electrode array failed after 114 days in 87 °C saline as a result of water penetration through the LCP-metal interface. An eye-conformable LCP package survived for 87 days in an accelerated condition at 87 °C. The in vivo results confirmed that no adverse effects were observed around the retina 2.5 years after the implantation of the device. SIGNIFICANCE These long-term evaluation results show the potential for the chronic use of LCP-based biomedical implants to provide an alternative to traditional metallic packages.
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Affiliation(s)
- Joonsoo Jeong
- Department of Electrical & Computer Engineering, Seoul National University, Seoul 151-742, Korea
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Guo A, Yan Z, Ye L, Zhang A, Feng Z. The Synthesis and Characterization of Spacer-Free Liquid Crystal Polyrotaxane by Virtue of the Mobility of Threaded α-Cyclodextrins. MACROMOL CHEM PHYS 2016. [DOI: 10.1002/macp.201500415] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Aiju Guo
- School of Materials Science and Engineering; Beijing Institute of Technology; Beijing 100081 China
| | - Zhi Yan
- School of Materials Science and Engineering; Beijing Institute of Technology; Beijing 100081 China
| | - Lin Ye
- School of Materials Science and Engineering; Beijing Institute of Technology; Beijing 100081 China
- Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications; Beijing 100081 China
| | - Aiying Zhang
- School of Materials Science and Engineering; Beijing Institute of Technology; Beijing 100081 China
- Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications; Beijing 100081 China
| | - Zengguo Feng
- School of Materials Science and Engineering; Beijing Institute of Technology; Beijing 100081 China
- Beijing Key Laboratory of Construction Tailorable Advanced Functional Materials and Green Applications; Beijing 100081 China
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