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Seo H, Chung WG, Kwon YW, Kim S, Hong YM, Park W, Kim E, Lee J, Lee S, Kim M, Lim K, Jeong I, Song H, Park JU. Smart Contact Lenses as Wearable Ophthalmic Devices for Disease Monitoring and Health Management. Chem Rev 2023; 123:11488-11558. [PMID: 37748126 PMCID: PMC10571045 DOI: 10.1021/acs.chemrev.3c00290] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Indexed: 09/27/2023]
Abstract
The eye contains a complex network of physiological information and biomarkers for monitoring disease and managing health, and ocular devices can be used to effectively perform point-of-care diagnosis and disease management. This comprehensive review describes the target biomarkers and various diseases, including ophthalmic diseases, metabolic diseases, and neurological diseases, based on the physiological and anatomical background of the eye. This review also includes the recent technologies utilized in eye-wearable medical devices and the latest trends in wearable ophthalmic devices, specifically smart contact lenses for the purpose of disease management. After introducing other ocular devices such as the retinal prosthesis, we further discuss the current challenges and potential possibilities of smart contact lenses.
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Affiliation(s)
- Hunkyu Seo
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Won Gi Chung
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Yong Won Kwon
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Sumin Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Yeon-Mi Hong
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Wonjung Park
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Enji Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Jakyoung Lee
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Sanghoon Lee
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Moohyun Kim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Kyeonghee Lim
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Inhea Jeong
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Hayoung Song
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
| | - Jang-Ung Park
- Department
of Materials Science and Engineering, Yonsei
University, Seoul 03722, Republic
of Korea
- Department
of Neurosurgery, Yonsei University College
of Medicine, Seoul 03722, Republic of Korea
- Center
for Nanomedicine, Institute for Basic Science (IBS), Yonsei University, Seoul 03722, Republic
of Korea
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Cha S, Ahn J, Jeong Y, Lee YH, Kim HK, Lee D, Yoo Y, Goo YS. Stage-Dependent Changes of Visual Function and Electrical Response of the Retina in the rd10 Mouse Model. Front Cell Neurosci 2022; 16:926096. [PMID: 35936494 PMCID: PMC9345760 DOI: 10.3389/fncel.2022.926096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/23/2022] [Indexed: 12/28/2022] Open
Abstract
One of the critical prerequisites for the successful development of retinal prostheses is understanding the physiological features of retinal ganglion cells (RGCs) in the different stages of retinal degeneration (RD). This study used our custom-made rd10 mice, C57BL/6-Pde6bem1(R560C)Dkl/Korl mutated on the Pde6b gene in C57BL/6J mouse with the CRISPR/Cas9-based gene-editing method. We selected the postnatal day (P) 45, P70, P140, and P238 as representative ages for RD stages. The optomotor response measured the visual acuity across degeneration stages. At P45, the rd10 mice exhibited lower visual acuity than wild-type (WT) mice. At P140 and older, no optomotor response was observed. We classified RGC responses to the flashed light into ON, OFF, and ON/OFF RGCs via in vitro multichannel recording. With degeneration, the number of RGCs responding to the light stimulation decreased in all three types of RGCs. The OFF response disappeared faster than the ON response with older postnatal ages. We elicited RGC spikes with electrical stimulation and analyzed the network-mediated RGC response in the rd10 mice. Across all postnatal ages, the spikes of rd10 RGCs were less elicited by pulse amplitude modulation than in WT RGCs. The ratio of RGCs showing multiple peaks of spike burst increased in older ages. The electrically evoked RGC spikes by the pulse amplitude modulation differ across postnatal ages. Therefore, degeneration stage-dependent stimulation strategies should be considered for developing retinal prosthesis and successful vision restoration.
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Affiliation(s)
- Seongkwang Cha
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Jungryul Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Yurim Jeong
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Yong Hee Lee
- Department of Biochemistry, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Hyong Kyu Kim
- Department of Microbiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Daekee Lee
- Department of Life Science, Ewha Womans University, Seoul, South Korea
| | - Yongseok Yoo
- Department of Electronics Engineering, Incheon National University, Incheon, South Korea
- *Correspondence: Yongseok Yoo,
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
- Yong Sook Goo,
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Fan P, Song Y, Lu B, Wang Y, Dai Y, Xie J, He E, Xu Z, Yang G, Mo F, Liu J, Wang M, Cai X. PtNPs/PEDOT:PSS-Modified Microelectrode Arrays Reveal Electrophysiological Activities of Different Neurons in Medial Amygdala of Mice Under Innate Fear. Front Neurosci 2022; 16:868235. [PMID: 35620664 PMCID: PMC9127061 DOI: 10.3389/fnins.2022.868235] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/11/2022] [Indexed: 12/19/2022] Open
Abstract
The medial amygdala (MA) plays an important role in the innate fear circuit. However, the electrophysiological mechanism of MA for processing innate fear needs to be further explored. In this study, we fabricated microelectrode arrays (MEAs) with detecting sites arranged to match the location and shape of MA in mice and detected the electrophysiology in freely behaving mice under 2-methyl-2-thiazoline (2MT)-induced fear. The detection performance of MEA is improved by modifying metal nanoparticles and conductive polymers (PtNPs/PEDOT:PSS). After modification, the impedance magnitude and phase of electrodes were decreased to 27.0 ± 2.3 kΩ and −12.30 ± 0.52°, respectively, leading to a signal-to-noise ratio of 10. Its electrochemical stability and mechanical stability were also verified by cyclic voltammetry (CV) sweeping and ultrasonic vibration. MEAs were then implanted into the MA of mice, and the electrophysiology and behavioral characteristics were synchronously recorded and analyzed. The results showed that 2MT induced strong defensive behaviors in mice, accompanied by increases in the average spike firing rate and local field potential (LFP) power of MA neurons. According to principles commonly applied to cortical extracellular recordings, the recorded neurons are divided into two classes based on waveforms. Statistics showed that about 37% of type 1 neurons (putative GABAergic neurons) and 87% of type 2 neurons (putative glutamatergic neurons) were significantly activated under innate fear. At the same time, the firing rate of some activated neurons had a good linear correlation with the freezing rate.
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Affiliation(s)
- Penghui Fan
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Yilin Song
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
- *Correspondence: Yilin Song
| | - Botao Lu
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Yiding Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Yuchuan Dai
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Jingyu Xie
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Enhui He
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Zhaojie Xu
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Gucheng Yang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Fan Mo
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Juntao Liu
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Mixia Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
| | - Xinxia Cai
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China
- School of Electronic, Electrical and Communication Engineering, University of the Chinese Academy of Sciences, Beijing, China
- Xinxia Cai
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Ahn J, Cha S, Choi KE, Kim SW, Yoo Y, Goo YS. Correlated Activity in the Degenerate Retina Inhibits Focal Response to Electrical Stimulation. Front Cell Neurosci 2022; 16:889663. [PMID: 35602554 PMCID: PMC9114441 DOI: 10.3389/fncel.2022.889663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 04/13/2022] [Indexed: 11/24/2022] Open
Abstract
Retinal prostheses have shown some clinical success in patients with retinitis pigmentosa and age-related macular degeneration. However, even after the implantation of a retinal prosthesis, the patient’s visual acuity is at best less than 20/420. Reduced visual acuity may be explained by a decrease in the signal-to-noise ratio due to the spontaneous hyperactivity of retinal ganglion cells (RGCs) found in degenerate retinas. Unfortunately, abnormal retinal rewiring, commonly observed in degenerate retinas, has rarely been considered for the development of retinal prostheses. The purpose of this study was to investigate the aberrant retinal network response to electrical stimulation in terms of the spatial distribution of the electrically evoked RGC population. An 8 × 8 multielectrode array was used to measure the spiking activity of the RGC population. RGC spikes were recorded in wild-type [C57BL/6J; P56 (postnatal day 56)], rd1 (P56), rd10 (P14 and P56) mice, and macaque [wild-type and drug-induced retinal degeneration (RD) model] retinas. First, we performed a spike correlation analysis between RGCs to determine RGC connectivity. No correlation was observed between RGCs in the control group, including wild-type mice, rd10 P14 mice, and wild-type macaque retinas. In contrast, for the RD group, including rd1, rd10 P56, and RD macaque retinas, RGCs, up to approximately 400–600 μm apart, were significantly correlated. Moreover, to investigate the RGC population response to electrical stimulation, the number of electrically evoked RGC spikes was measured as a function of the distance between the stimulation and recording electrodes. With an increase in the interelectrode distance, the number of electrically evoked RGC spikes decreased exponentially in the control group. In contrast, electrically evoked RGC spikes were observed throughout the retina in the RD group, regardless of the inter-electrode distance. Taken together, in the degenerate retina, a more strongly coupled retinal network resulted in the widespread distribution of electrically evoked RGC spikes. This finding could explain the low-resolution vision in prosthesis-implanted patients.
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Affiliation(s)
- Jungryul Ahn
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Seongkwang Cha
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
| | - Kwang-Eon Choi
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
| | - Seong-Woo Kim
- Department of Ophthalmology, Korea University College of Medicine, Seoul, South Korea
- *Correspondence: Seong-Woo Kim,
| | - Yongseok Yoo
- Department of Electronics Engineering, Incheon National University, Incheon, South Korea
- Yongseok Yoo,
| | - Yong Sook Goo
- Department of Physiology, Chungbuk National University School of Medicine, Cheongju, South Korea
- Yong Sook Goo,
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Selective Passivation of Three-Dimensional Carbon Microelectrodes by Polydopamine Electrodeposition and Local Laser Ablation. MICROMACHINES 2022; 13:mi13030371. [PMID: 35334663 PMCID: PMC8950879 DOI: 10.3390/mi13030371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/22/2022] [Accepted: 02/23/2022] [Indexed: 02/04/2023]
Abstract
In this article, a novel approach for selective passivation of three-dimensional pyrolytic carbon microelectrodes via a facile electrochemical polymerization of a non-conductive polymer (polydopamine, PDA) onto the surface of carbon electrodes, followed by a selective laser ablation is elaborated. The 3D carbon electrodes consisting of 284 micropillars on a circular 2D carbon base layer were fabricated by pyrolysis of lithographically patterned negative photoresist SU-8. As a second step, dopamine was electropolymerized onto the electrode by cyclic voltammetry (CV) to provide an insulating layer at its surface. The CV parameters, such as the scan rate and the number of cycles, were investigated and optimized to achieve a reliable and uniform non-conductive coating on the surface of the 3D pyrolytic carbon electrode. Finally, the polydopamine was selectively removed only from the tips of the pillars, by using localized laser ablation. The selectively passivated electrodes were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy methods. Due to the surface being composed of highly biocompatible materials, such as pyrolytic carbon and polydopamine, these 3D electrodes are particularly suited for biological application, such as electrochemical monitoring of cells or retinal implants, where highly localized electrical stimulation of nerve cells is beneficial.
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Huan Y, Gill JP, Fritzinger JB, Patel PR, Richie JM, Valle ED, Weiland JD, Chestek CA, Chiel HJ. Carbon fiber electrodes for intracellular recording and stimulation. J Neural Eng 2021; 18:10.1088/1741-2552/ac3dd7. [PMID: 34826825 PMCID: PMC10729305 DOI: 10.1088/1741-2552/ac3dd7] [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: 08/10/2021] [Accepted: 11/26/2021] [Indexed: 01/18/2023]
Abstract
Objective.To understand neural circuit dynamics, it is critical to manipulate and record many individual neurons. Traditional recording methods, such as glass microelectrodes, can only control a small number of neurons. More recently, devices with high electrode density have been developed, but few of them can be used for intracellular recording or stimulation in intact nervous systems. Carbon fiber electrodes (CFEs) are 8µm-diameter electrodes that can be assembled into dense arrays (pitches ⩾ 80µm). They have good signal-to-noise ratios (SNRs) and provide stable extracellular recordings both acutely and chronically in neural tissuein vivo(e.g. rat motor cortex). The small fiber size suggests that arrays could be used for intracellular stimulation.Approach.We tested CFEs for intracellular stimulation using the large identified and electrically compact neurons of the marine molluskAplysia californica. Neuron cell bodies inAplysiarange from 30µm to over 250µm. We compared the efficacy of CFEs to glass microelectrodes by impaling the same neuron's cell body with both electrodes and connecting them to a DC coupled amplifier.Main results.We observed that intracellular waveforms were essentially identical, but the amplitude and SNR in the CFE were lower than in the glass microelectrode. CFE arrays could record from 3 to 8 neurons simultaneously for many hours, and many of these recordings were intracellular, as shown by simultaneous glass microelectrode recordings. CFEs coated with platinum-iridium could stimulate and had stable impedances over many hours. CFEs not within neurons could record local extracellular activity. Despite the lower SNR, the CFEs could record synaptic potentials. CFEs were less sensitive to mechanical perturbations than glass microelectrodes.Significance.The ability to do stable multi-channel recording while stimulating and recording intracellularly make CFEs a powerful new technology for studying neural circuit dynamics.
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Affiliation(s)
- Yu Huan
- Department of Biology, Case Western Reserve University, Cleveland, OH, United States of America
| | - Jeffrey P Gill
- Department of Biology, Case Western Reserve University, Cleveland, OH, United States of America
| | - Johanna B Fritzinger
- Department of Neurosciences, University of Rochester, Rochester, NY, United States of America
| | - Paras R Patel
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Julianna M Richie
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
| | - Elena Della Valle
- Department of Biomedical Engineering, 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
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI, United States of America
| | - Cynthia A Chestek
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Biointerfaces Institute, University of Michigan, Ann Arbor, MI, United States of America
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, United States of America
- Neurosciences Program, University of Michigan, Ann Arbor, MI, United States of America
- Robotics Program, University of Michigan, Ann Arbor, MI, United States of America
| | - Hillel J Chiel
- Department of Biology, Case Western Reserve University, Cleveland, OH, United States of America
- Department of Neurosciences, Case Western Reserve University, Cleveland, OH, United States of America
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States of America
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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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Seo HW, Kim N, Kim S. Fabrication of Subretinal 3D Microelectrodes with Hexagonal Arrangement. MICROMACHINES 2020; 11:mi11050467. [PMID: 32365472 PMCID: PMC7281732 DOI: 10.3390/mi11050467] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 02/01/2023]
Abstract
This study presents the fabrication of three-dimensional (3D) microelectrodes for subretinal stimulation, to accommodate adjacent return electrodes surrounding a stimulating electrode. For retinal prosthetic devices, the arrangement of return electrodes, the electrode size and spacing should be considered together, to reduce the undesired dissipation of electric currents. Here, we applied the hexagonal arrangement to the microelectrode array for the localized activation of retinal cells and better visual acuity. To provide stimuli more efficiently to non-spiking neurons, a 3D structure was created through a customized pressing process, utilizing the elastic property of the materials used in the fabrication processes. The diameter and pitch of the Pt-coated electrodes were 150 μm and 350 μm, respectively, and the height of the protruded electrodes was around 20 μm. The array consisted of 98 hexagonally arranged electrodes, supported by a flexible and transparent polydimethylsiloxane (PDMS) base, with a thickness of 140 μm. Also, the array was coated with 2 μm-thick parylene-C, except the active electrode sites, for more focused stimulation. Finally, the electrochemical properties of the fabricated microelectrodes were characterized, resulting in the mean impedance of 384.87 kΩ at 1 kHz and the charge storage capacity (CSC) of 2.83 mC·cm−2. The fabricated microelectrodes are to be combined with an integrated circuit (IC) for additional in vitro and in vivo experiments.
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Affiliation(s)
| | | | - Sohee Kim
- Correspondence: ; Tel.: +82-53-785-6217
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Xia Y, Mo Y, Meng W, Du X, Ma C. Graphene/Carbon Paper Combined with Redox Active Electrolyte for Supercapacitors with High Performance. Polymers (Basel) 2019; 11:E1355. [PMID: 31426288 PMCID: PMC6722702 DOI: 10.3390/polym11081355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 08/06/2019] [Accepted: 08/12/2019] [Indexed: 11/17/2022] Open
Abstract
Graphene/carbon paper is prepared by pyrolyzing graphene modified cellulose filter paper and directly used as a binder-free electrode to assemble a supercapacitor (SC) with a redox active electrolyte, containing a Fe3+/Fe2+ additive. By the graphene incorporation and the carbonization of the cellulose fibers, both the microstructure and the electrical conductivity of the carbon paper are promoted greatly. The filter paper derived carbon (FPC) electrode exhibits a specific capacitance (Cs) of 2832 F·g-1 in a 1 M H2SO4 + 0.5 M Fe3+/Fe2+ electrolyte at 1 A·g-1, which is about 81 times that in a normal H2SO4 electrolyte. With the modification of graphene, the capacitive performance of the SC is enhanced further and a remarkable Cs of 3396 F·g-1 at 1 A·g-1 is achieved for a graphene modified filter paper carbon (GFPC) electrode, which remains at ~632 F·g-1 at 10 A·g-1. The free standing GFPC electrode also exhibits good cycling stability (93.8% of capacitance retention after 2000 cycles) and an energy density of 118 Wh·kg-1 at a power density of 500.35 W·kg-1, all of which are much higher than those of FPC. These encouraging results suggest that the graphene modification of electrode materials combined with a Fe3+/Fe2+ redox active electrolyte is a prospective measure to fabricate SC with an ultrahigh performance.
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Affiliation(s)
- Yanlin Xia
- Institute of Advanced Wear & Corrosion Resistance and Functional Materials, Jinan University, Guangzhou 510632, China
| | - Youtian Mo
- Institute of Advanced Wear & Corrosion Resistance and Functional Materials, Jinan University, Guangzhou 510632, China
| | - Wei Meng
- Institute of Advanced Wear & Corrosion Resistance and Functional Materials, Jinan University, Guangzhou 510632, China
| | - Xusheng Du
- Institute of Advanced Wear & Corrosion Resistance and Functional Materials, Jinan University, Guangzhou 510632, China.
| | - Chuanguo Ma
- Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, China
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