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Santiago-Alvarado A, Granados-Agustín FS, López-Raymundo BR, Hernández-Mendez A, Huerta-Carranza O. Development of a bio-inspired optical system that mimics accommodation and lighting regulation like the human eye. APPLIED OPTICS 2024; 63:193-203. [PMID: 38175021 DOI: 10.1364/ao.506986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 12/02/2023] [Indexed: 01/05/2024]
Abstract
Bio-inspired optical systems have recently been developed using polarizers and liquid or rigid lenses. In this work, we propose a bio-inspired opto-mechatronic system that imitates the accommodation and regulation of light intensity as the human eye does. The system uses a polymeric lens as a cornea, an adjustable diaphragm as an iris, a tunable solid elastic lens as a crystalline lens, and a commercial sensor as a retina. We also present the development of the electronic control system to accommodate and regulate the amount of light that enters the system, for which two stepper motors, an Arduino control system, and light and movement sensors are used. The characterization of the system is presented together with the results obtained, where it can be seen that the system works in an acceptable range as the human eye does.
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Park B, Bang S, Hwang KS, Cha YK, Kwak J, Tran NL, Kim HS, Park S, Oh SJ, Im M, Chung S, Kim J, Park TH, Song HS, Kim HN, Kim JH. Eye-Mimicked Neural Network Composed of Photosensitive Neural Spheroids with Human Opsin Proteins. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2302996. [PMID: 37377148 DOI: 10.1002/adma.202302996] [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: 03/31/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 06/29/2023]
Abstract
An in vitro model, composed of the short-wavelength human opsins and rhodopsins, is created. Two types of photosensitive neural spheroids are transfected for selective reaction under bluish-purple and green lights. These are employed to two devices with intact neuron and neural-spheroid to study the interaction. By photostimulation, the photosensitive spheroid initiated photoactivation, and the signal generated from its body is transmitted to adjacent neural networks. Specifically, the signal traveled through the axon bundle in narrow gap from photosensitive spheroid to intact spheroid as an eye-to-brain model including optic nerve. The whole process with photosensitive spheroid is monitored by calcium ion detecting fluorescence images. The results of this study can be applied to examine vision restoration and novel photosensitive biological systems with spectral sensitivity.
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Affiliation(s)
- Byeongho Park
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Seokyoung Bang
- Department of Biomedical Engineering, Dongguk University, Goyang, 10326, Republic of Korea
| | - Kyeong Seob Hwang
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
- School of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Yeon Kyung Cha
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Jisung Kwak
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Na Ly Tran
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology, Seoul, 02792, Republic of Korea
| | - Hyo-Suk Kim
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Subeen Park
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Seung Ja Oh
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology, Seoul, 02792, Republic of Korea
| | - Maesoon Im
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Sooyoung Chung
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Jongbaeg Kim
- School of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Tai Hyun Park
- Department of Nutritional Science and Food Management, Ewha Womans University, Seodaemun-gu, Seoul, 03760, Republic of Korea
| | - Hyun Seok Song
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Hong Nam Kim
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
- School of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
- Division of Bio-Medical Science & Technology, KIST School, University of Science and Technology, Seoul, 02792, Republic of Korea
- Yonsei-KIST Convergence Research Institute, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jae Hun Kim
- Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
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Xu C, Lu G, Kang H, Humayun MS, Zhou Q. Design and Simulation of a Ring Transducer Array for Ultrasound Retinal Stimulation. MICROMACHINES 2022; 13:1536. [PMID: 36144157 PMCID: PMC9503310 DOI: 10.3390/mi13091536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/22/2022] [Accepted: 09/10/2022] [Indexed: 06/16/2023]
Abstract
Argus II retinal prosthesis is the US Food and Drug Administration (FDA) approved medical device intended to restore sight to a patient's blind secondary to retinal degeneration (i.e., retinitis pigmentosa). However, Argus II and most reported retinal prostheses require invasive surgery to implant electrodes in the eye. Recent studies have shown that focused ultrasound can be developed into a non-invasive retinal prosthesis technology. Ultrasound energy focused on retinal neurons can trigger the activities of retinal neurons with high spatial-temporal resolution. This paper introduces a novel design and simulation of a ring array transducer that could be used as non-invasive ultrasonic retinal stimulation. The array transducer is designed in the shape of a racing ring with a hemisphere surface that mimics a contact lens to acoustically couple with the eye via the tear film and directs the ultrasound to avoid the high acoustic absorption from the crystalline lens. We will describe the design methods and simulation of the two-dimensional pattern stimulation. Finally, compared with other existing retinal prostheses, we show that the ultrasound ring array is practical and safe and could be potentially used as a non-invasive retinal prosthesis.
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Affiliation(s)
- Chenlin Xu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Gengxi Lu
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Haochen Kang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
| | - Mark S. Humayun
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
| | - Qifa Zhou
- Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA
- USC Roski Eye Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
- USC Ginsburg Institute for Biomedical Therapeutics, University of Southern California, Los Angeles, CA 90033, USA
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Wang J, Zhao R, Li P, Fang Z, Li Q, Han Y, Zhou R, Zhang Y. Clinical Progress and Optimization of Information Processing in Artificial Visual Prostheses. SENSORS (BASEL, SWITZERLAND) 2022; 22:6544. [PMID: 36081002 PMCID: PMC9460383 DOI: 10.3390/s22176544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/22/2022] [Accepted: 08/26/2022] [Indexed: 06/15/2023]
Abstract
Visual prostheses, used to assist in restoring functional vision to the visually impaired, convert captured external images into corresponding electrical stimulation patterns that are stimulated by implanted microelectrodes to induce phosphenes and eventually visual perception. Detecting and providing useful visual information to the prosthesis wearer under limited artificial vision has been an important concern in the field of visual prosthesis. Along with the development of prosthetic device design and stimulus encoding methods, researchers have explored the possibility of the application of computer vision by simulating visual perception under prosthetic vision. Effective image processing in computer vision is performed to optimize artificial visual information and improve the ability to restore various important visual functions in implant recipients, allowing them to better achieve their daily demands. This paper first reviews the recent clinical implantation of different types of visual prostheses, summarizes the artificial visual perception of implant recipients, and especially focuses on its irregularities, such as dropout and distorted phosphenes. Then, the important aspects of computer vision in the optimization of visual information processing are reviewed, and the possibilities and shortcomings of these solutions are discussed. Ultimately, the development direction and emphasis issues for improving the performance of visual prosthesis devices are summarized.
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Affiliation(s)
- Jing Wang
- School of Information, Shanghai Ocean University, Shanghai 201306, China
- Key Laboratory of Fishery Information, Ministry of Agriculture, Shanghai 200335, China
| | - Rongfeng Zhao
- School of Information, Shanghai Ocean University, Shanghai 201306, China
| | - Peitong Li
- School of Information, Shanghai Ocean University, Shanghai 201306, China
| | - Zhiqiang Fang
- School of Information, Shanghai Ocean University, Shanghai 201306, China
| | - Qianqian Li
- School of Information, Shanghai Ocean University, Shanghai 201306, China
| | - Yanling Han
- School of Information, Shanghai Ocean University, Shanghai 201306, China
| | - Ruyan Zhou
- School of Information, Shanghai Ocean University, Shanghai 201306, China
| | - Yun Zhang
- School of Information, Shanghai Ocean University, Shanghai 201306, China
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Manousiouthakis E, Park J, Hardy JG, Lee JY, Schmidt CE. Towards the translation of electroconductive organic materials for regeneration of neural tissues. Acta Biomater 2022; 139:22-42. [PMID: 34339871 DOI: 10.1016/j.actbio.2021.07.065] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 12/13/2022]
Abstract
Carbon-based conductive and electroactive materials (e.g., derivatives of graphene, fullerenes, polypyrrole, polythiophene, polyaniline) have been studied since the 1970s for use in a broad range of applications. These materials have electrical properties comparable to those of commonly used metals, while providing other benefits such as flexibility in processing and modification with biologics (e.g., cells, biomolecules), to yield electroactive materials with biomimetic mechanical and chemical properties. In this review, we focus on the uses of these electroconductive materials in the context of the central and peripheral nervous system, specifically recent studies in the peripheral nerve, spinal cord, brain, eye, and ear. We also highlight in vivo studies and clinical trials, as well as a snapshot of emerging classes of electroconductive materials (e.g., biodegradable materials). We believe such specialized electrically conductive biomaterials will clinically impact the field of tissue regeneration in the foreseeable future. STATEMENT OF SIGNIFICANCE: This review addresses the use of conductive and electroactive materials for neural tissue regeneration, which is of significant interest to a broad readership, and of particular relevance to the growing community of scientists, engineers and clinicians in academia and industry who develop novel medical devices for tissue engineering and regenerative medicine. The review covers the materials that may be employed (primarily focusing on derivatives of fullerenes, graphene and conjugated polymers) and techniques used to analyze materials composed thereof, followed by sections on the application of these materials to nervous tissues (i.e., peripheral nerve, spinal cord, brain, optical, and auditory tissues) throughout the body.
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Affiliation(s)
- Eleana Manousiouthakis
- Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville 32611, FL, United States
| | - Junggeon Park
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea
| | - John G Hardy
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, United Kingdom; Materials Science Institute, Lancaster University, Lancaster LA1 4YB, United Kingdom.
| | - Jae Young Lee
- School of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 61005, Republic of Korea.
| | - Christine E Schmidt
- Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville 32611, FL, United States.
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Silva AE, Tsang K, Hasan SJ, Thompson B. Precise oculocentric mapping of transcranial magnetic stimulation-evoked phosphenes. Neuroreport 2021; 32:913-917. [PMID: 34102648 PMCID: PMC8253501 DOI: 10.1097/wnr.0000000000001683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 05/10/2021] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Transcranial magnetic stimulation (TMS)-evoked phosphenes are oculocentric; their perceived location depends upon eye position. We investigated the accuracy and precision of TMS-evoked phosphene oculocentric mapping. METHODS We evoked central phosphenes by stimulating early visual cortical areas with TMS, systematically examining the effect of eye position by asking participants to report the location of the evoked phosphene. We tested whether any systematic differences in the precision or accuracy of responses occurred as a function of eye position. RESULTS Perceived phosphene locations map veridically to eye position, although there are considerable individual differences in the reliability of this mapping. CONCLUSIONS Our results emphasize the need to carefully control eye movements when carrying out phosphene localization studies and suggest that individual differences in the reliability of the reported position of individual phosphenes must be considered.
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Affiliation(s)
- Andrew E. Silva
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
| | - Katelyn Tsang
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
| | - Syeda Javeria Hasan
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
| | - Benjamin Thompson
- School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
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A Novel Antimicrobial Peptide (Kassinatuerin-3) Isolated from the Skin Secretion of the African Frog, Kassina senegalensis. BIOLOGY 2020; 9:biology9070148. [PMID: 32630734 PMCID: PMC7408539 DOI: 10.3390/biology9070148] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/21/2020] [Accepted: 06/24/2020] [Indexed: 01/05/2023]
Abstract
Amphibian skin secretions are remarkable sources of novel bioactive peptides. Among these, antimicrobial peptides have demonstrated an outstanding efficacy in killing microorganisms via a general membranolytic mechanism, which may offer the prospect of solving specific target-driven antibiotic resistance. Here, the discovery of a novel defensive peptide is described from the skin secretion of the African frog, Kassina senegalensis. Named kassinatuerin-3, it was identified through a combination of “shot-gun” cloning and MS/MS fragmentation sequencing. Subsequently, a synthetic replicate was subjected to biofunctional evaluation. The results indicated that kassinatuerin-3 possessed antimicrobial activity against Gram-positive bacteria but no effect against Gram-negative bacteria. Additionally, it was active in biofilm eradication on S. aureus and MRSA and in the antiproliferation of selected cancer cell lines. Moreover, it had a very mild hemolytic effect, which demonstrated a high therapeutic index for kassinatuerin-3. Collectively, although kassinatuerin-3 did not demonstrate remarkable bioactivities compared with other natural or synthetic antimicrobial peptides (AMPs), it offered a new insight into the design of antimicrobial derivatives.
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Jiang Q, Li G, Zhao H, Sheng W, Yue L, Su M, Weng S, Chan LLH, Zhou Q, Humayun MS, Qiu W, Zheng H. Temporal Neuromodulation of Retinal Ganglion Cells by Low-Frequency Focused Ultrasound Stimulation. IEEE Trans Neural Syst Rehabil Eng 2019; 26:969-976. [PMID: 29752231 DOI: 10.1109/tnsre.2018.2821194] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Significant progress has been made recently in treating neurological blindness using implantable visual prostheses. However, implantable medical devices are highly invasive and subject to many safety, efficacy, and cost issues. The discovery that ultrasound (US) may be useful as a noninvasive neuromodulation tool has aroused great interest in the field of acoustic retinal prostheses (ARPs). We have investigated the responsiveness of rat retinal ganglion cells (RGCs) to low-frequency focused US stimulation (LFUS) at 2.25 MHz and characterized the neurophysiological properties of US responses by performing in vitro multielectrode array recordings. The results show that LFUS can reliably activate RGCs. The US-induced responses did not correspond to the standard light responses and varied greatly among cell types. Moreover, dual-peak responses to US stimulation were observed that have not been reported previously. The temporal response properties of RGCs, including their latency, firing rate, and response type, were modulated by the acoustic intensity. These findings suggest the presence of a temporal neuromodulation effect of LFUS and potentially open a new avenue in the development of ARP.
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Artificial Intelligence and Big Data in Public Health. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2018; 15:ijerph15122796. [PMID: 30544648 PMCID: PMC6313588 DOI: 10.3390/ijerph15122796] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/23/2018] [Accepted: 12/05/2018] [Indexed: 12/31/2022]
Abstract
Artificial intelligence and automation are topics dominating global discussions on the future of professional employment, societal change, and economic performance. In this paper, we describe fundamental concepts underlying AI and Big Data and their significance to public health. We highlight issues involved and describe the potential impacts and challenges to medical professionals and diagnosticians. The possible benefits of advanced data analytics and machine learning are described in the context of recently reported research. Problems are identified and discussed with respect to ethical issues and the future roles of professionals and specialists in the age of artificial intelligence.
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Woods V, Trumpis M, Bent B, Palopoli-Trojani K, Chiang CH, Wang C, Yu C, Insanally MN, Froemke RC, Viventi J. Long-term recording reliability of liquid crystal polymer µECoG arrays. J Neural Eng 2018; 15:066024. [PMID: 30246690 PMCID: PMC6342453 DOI: 10.1088/1741-2552/aae39d] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The clinical use of microsignals recorded over broad cortical regions is largely limited by the chronic reliability of the implanted interfaces. APPROACH We evaluated the chronic reliability of novel 61-channel micro-electrocorticographic (µECoG) arrays in rats chronically implanted for over one year and using accelerated aging. Devices were encapsulated with polyimide (PI) or liquid crystal polymer (LCP), and fabricated using commercial manufacturing processes. In vitro failure modes and predicted lifetimes were determined from accelerated soak testing. Successful designs were implanted epidurally over the rodent auditory cortex. Trends in baseline signal level, evoked responses and decoding performance were reported for over one year of implantation. MAIN RESULTS Devices fabricated with LCP consistently had longer in vitro lifetimes than PI encapsulation. Our accelerated aging results predicted device integrity beyond 3.4 years. Five implanted arrays showed stable performance over the entire implantation period (247-435 d). Our regression analysis showed that impedance predicted signal quality and information content only in the first 31 d of recordings and had little predictive value in the chronic phase (>31 d). In the chronic phase, site impedances slightly decreased yet decoding performance became statistically uncorrelated with impedance. We also employed an improved statistical model of spatial variation to measure sensitivity to locally varying fields, which is typically concealed in standard signal power calculations. SIGNIFICANCE These findings show that µECoG arrays can reliably perform in chronic applications in vivo for over one year, which facilitates the development of a high-density, clinically viable interface.
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Affiliation(s)
- Virginia Woods
- Department of Biomedical Engineering, Duke University, Durham, NC, United States of America
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Wienbar S, Schwartz GW. The dynamic receptive fields of retinal ganglion cells. Prog Retin Eye Res 2018; 67:102-117. [PMID: 29944919 PMCID: PMC6235744 DOI: 10.1016/j.preteyeres.2018.06.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 06/15/2018] [Accepted: 06/20/2018] [Indexed: 11/30/2022]
Abstract
Retinal ganglion cells (RGCs) were one of the first classes of sensory neurons to be described in terms of a receptive field (RF). Over the last six decades, our understanding of the diversity of RGC types and the nuances of their response properties has grown exponentially. We will review the current understanding of RGC RFs mostly from studies in mammals, but including work from other vertebrates as well. We will argue for a new paradigm that embraces the fluidity of RGC RFs with an eye toward the neuroethology of vision. Specifically, we will focus on (1) different methods for measuring RGC RFs, (2) RF models, (3) feature selectivity and the distinction between fluid and stable RF properties, and (4) ideas about the future of understanding RGC RFs.
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Affiliation(s)
- Sophia Wienbar
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, United States.
| | - Gregory W Schwartz
- Departments of Ophthalmology and Physiology, Feinberg School of Medicine, Northwestern University, United States.
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Mehrali M, Bagherifard S, Akbari M, Thakur A, Mirani B, Mehrali M, Hasany M, Orive G, Das P, Emneus J, Andresen TL, Dolatshahi‐Pirouz A. Blending Electronics with the Human Body: A Pathway toward a Cybernetic Future. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1700931. [PMID: 30356969 PMCID: PMC6193179 DOI: 10.1002/advs.201700931] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 05/24/2018] [Indexed: 05/22/2023]
Abstract
At the crossroads of chemistry, electronics, mechanical engineering, polymer science, biology, tissue engineering, computer science, and materials science, electrical devices are currently being engineered that blend directly within organs and tissues. These sophisticated devices are mediators, recorders, and stimulators of electricity with the capacity to monitor important electrophysiological events, replace disabled body parts, or even stimulate tissues to overcome their current limitations. They are therefore capable of leading humanity forward into the age of cyborgs, a time in which human biology can be hacked at will to yield beings with abilities beyond their natural capabilities. The resulting advances have been made possible by the emergence of conformal and soft electronic materials that can readily integrate with the curvilinear, dynamic, delicate, and flexible human body. This article discusses the recent rapid pace of development in the field of cybernetics with special emphasis on the important role that flexible and electrically active materials have played therein.
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Affiliation(s)
- Mehdi Mehrali
- Technical University of DenmarkDTU NanotechCenter for Nanomedicine and Theranostics2800KgsDenmark
| | - Sara Bagherifard
- Department of Mechanical EngineeringPolitecnico di Milano20156MilanItaly
| | - Mohsen Akbari
- Laboratory for Innovations in MicroEngineering (LiME)Department of Mechanical EngineeringUniversity of VictoriaVictoriaBCV8P 5C2Canada
- Center for Biomedical ResearchUniversity of VictoriaVictoriaV8P 5C2Canada
- Center for Advanced Materials and Related Technologies (CAMTEC)University of VictoriaVictoriaV8P 5C2Canada
| | - Ashish Thakur
- Technical University of DenmarkDTU NanotechCenter for Nanomedicine and Theranostics2800KgsDenmark
| | - Bahram Mirani
- Laboratory for Innovations in MicroEngineering (LiME)Department of Mechanical EngineeringUniversity of VictoriaVictoriaBCV8P 5C2Canada
- Center for Biomedical ResearchUniversity of VictoriaVictoriaV8P 5C2Canada
- Center for Advanced Materials and Related Technologies (CAMTEC)University of VictoriaVictoriaV8P 5C2Canada
| | - Mohammad Mehrali
- Process and Energy DepartmentDelft University of TechnologyLeeghwaterstraat 392628CBDelftThe Netherlands
| | - Masoud Hasany
- Technical University of DenmarkDTU NanotechCenter for Nanomedicine and Theranostics2800KgsDenmark
| | - Gorka Orive
- NanoBioCel GroupLaboratory of PharmaceuticsSchool of PharmacyUniversity of the Basque Country UPV/EHUPaseo de la Universidad 701006Vitoria‐GasteizSpain
- Biomedical Research Networking Centre in Bioengineering, Biomaterials, and Nanomedicine (CIBER‐BBN)Vitoria‐Gasteiz28029Spain
- University Institute for Regenerative Medicine and Oral Implantology—UIRMI (UPV/EHU‐Fundación Eduardo Anitua)Vitoria01007Spain
| | - Paramita Das
- School of Chemical and Biomedical EngineeringNanyang Technological University62 Nanyang DriveSingapore637459Singapore
| | - Jenny Emneus
- Technical University of DenmarkDTU Nanotech2800KgsDenmark
| | - Thomas L. Andresen
- Technical University of DenmarkDTU NanotechCenter for Nanomedicine and Theranostics2800KgsDenmark
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Gamieldien R, Stemmet L, Javer J, Fortuin E, Clarke-Farr PC. Emerging technologies in artificial ocular devices: A systematic review. AFRICAN VISION AND EYE HEALTH 2018. [DOI: 10.4102/aveh.v77i1.428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Soto-Breceda A, Kameneva T, Meffin H, Maturana M, Ibbotson MR. Irregularly timed electrical pulses reduce adaptation of retinal ganglion cells. J Neural Eng 2018; 15:056017. [PMID: 30021932 DOI: 10.1088/1741-2552/aad46e] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Retinal prostheses aim to provide visual percepts to blind people affected by diseases caused by photoreceptor degeneration. One of the main challenges presented by current devices is neural adaptation in the retina, which is believed to be the cause of fading-an effect where artificially produced percepts disappear over a short period of time, despite continuous stimulation of the retina. We aim to understand the neural adaptation generated in retinal ganglion cells (RGCs) during electrical stimulation. APPROACH Current visual prostheses use electrical pulses with fixed frequencies and amplitudes modulated over hundreds of milliseconds to stimulate the retina. However, in nature, neuronal spiking occurs with stochastic timing, hence the information received naturally from other neurons by RGCs is irregularly timed. We used a single epiretinal electrode to stimulate and compare rat RGC responses to stimulus trains of biphasic pulses delivered at regular and random inter-pulse intervals (IPI), the latter taken from an exponential distribution. MAIN RESULTS Our observations suggest that stimulation with random IPIs result in lower adaptation rates than stimulation with constant IPIs at frequencies of 50 Hz and 200 Hz. We also found a high proportion of lower amplitude action potentials, or spikelets. The spikelets were more prominent at high stimulation frequencies (50 Hz and 200 Hz) and were less susceptible to adaptation, but it was not clear if they propagated along the axon. SIGNIFICANCE Using random IPI stimulation in retinal prostheses reduces the decay of RGCs and this could potentially reduce fading of electrically induced visual perception.
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Affiliation(s)
- A Soto-Breceda
- National Vision Research Institute, Australian College of Optometry, Melbourne, Australia. Department of Biomedical Engineering, The University of Melbourne, Melbourne, Australia. CSIRO, Data 61, Melbourne, Australia
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Gao M, Yu Y, Zhao H, Li G, Jiang H, Wang C, Cai F, Chan LLH, Chiu B, Qian W, Qiu W, Zheng H. Simulation Study of an Ultrasound Retinal Prosthesis With a Novel Contact-Lens Array for Noninvasive Retinal Stimulation. IEEE Trans Neural Syst Rehabil Eng 2017; 25:1605-1611. [PMID: 28320674 DOI: 10.1109/tnsre.2017.2682923] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Millions of people around the world suffer from varying degrees of vision loss (including complete blindness) because of retinal degenerative diseases. Artificial retinal prosthesis, which is usually based on electrical neurostimulation, is the most advanced technology for different types of retinal degeneration. However, this technology involves placing a device into the eyeball, and such a highly invasive procedure is inevitably highly risk and expensive. Ultrasound has been demonstrated to be a promising technology for noninvasive neurostimulation, making it possible to stimulate the retina and induce action potentials similar to those elicited by light stimulation. However, the technology of ultrasound retinal stimulation still requires considerable developments before it could be applied clinically. This paper proposes a novel contact-lens array transducer for use in an ultrasound retinal prosthesis (USRP). The transducer was designed in the shape of a contact lens so as to facilitate acoustic coupling with the eye liquid. The key parameters of the ultrasound transducer were simulated, and results are presented that indicate the achievement of 2-D pattern generation and that the proposed contact-lens array is suitable for multiple-focus neurostimulation, and can be used in a USRP.
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16
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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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17
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Jung JH, Pu T, Peli E. Comparing object recognition from binary and bipolar edge images for visual prostheses. JOURNAL OF ELECTRONIC IMAGING 2016; 25:061619. [PMID: 28458481 PMCID: PMC5407304 DOI: 10.1117/1.jei.25.6.061619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Visual prostheses require an effective representation method due to the limited display condition which has only 2 or 3 levels of grayscale in low resolution. Edges derived from abrupt luminance changes in images carry essential information for object recognition. Typical binary (black and white) edge images have been used to represent features to convey essential information. However, in scenes with a complex cluttered background, the recognition rate of the binary edge images by human observers is limited and additional information is required. The polarity of edges and cusps (black or white features on a gray background) carries important additional information; the polarity may provide shape from shading information missing in the binary edge image. This depth information may be restored by using bipolar edges. We compared object recognition rates from 16 binary edge images and bipolar edge images by 26 subjects to determine the possible impact of bipolar filtering in visual prostheses with 3 or more levels of grayscale. Recognition rates were higher with bipolar edge images and the improvement was significant in scenes with complex backgrounds. The results also suggest that erroneous shape from shading interpretation of bipolar edges resulting from pigment rather than boundaries of shape may confound the recognition.
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Affiliation(s)
- Jae-Hyun Jung
- Harvard Medical School, Massachusetts Eye and Ear, Department of Ophthalmology, Schepens Eye Research Institute, 20 Staniford Street, Boston, Massachusetts 02114, United States
| | - Tian Pu
- Harvard Medical School, Massachusetts Eye and Ear, Department of Ophthalmology, Schepens Eye Research Institute, 20 Staniford Street, Boston, Massachusetts 02114, United States
- University of Electronic Science and Technology of China, School of Optoelectronic Information, No. 4, Section 2, North Jianshe Road, Chengdu 610054, China
| | - Eli Peli
- Harvard Medical School, Massachusetts Eye and Ear, Department of Ophthalmology, Schepens Eye Research Institute, 20 Staniford Street, Boston, Massachusetts 02114, United States
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18
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Svechtarova MI, Buzzacchera I, Toebes BJ, Lauko J, Anton N, Wilson CJ. Sensor Devices Inspired by the Five Senses: A Review. ELECTROANAL 2016. [DOI: 10.1002/elan.201600047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
| | | | - B. Jelle Toebes
- NovioSense BV; Transistorweg 5 6534 AT Nijmegen The Netherlands
| | - Jan Lauko
- NovioSense BV; Transistorweg 5 6534 AT Nijmegen The Netherlands
| | - Nicoleta Anton
- Universitatea de Medicina si Farmacie Grigore T.; Popa, Str. Universitatii nr. 16 700115 Iasi Romania
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19
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Lowery AJ, Rosenfeld JV, Lewis PM, Browne D, Mohan A, Brunton E, Yan E, Maller J, Mann C, Rajan R, Rosa M, Pritchard J. Restoration of vision using wireless cortical implants: The Monash Vision Group project. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2015:1041-1044. [PMID: 26736443 DOI: 10.1109/embc.2015.7318543] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Monash Vision Group is developing a bionic vision system based on implanting several small tiles in the V1 region of the visual cortex. This cortical approach could benefit a greater proportion of people with total blindness than other approaches, as it bypasses the eyes and optic nerve. Each tile has 43 active electrodes on its base, and a wirelessly powered electronic system to decode control signals and drive the electrodes with biphasic pulses. The tiles are fed with power and data using a common transmitting coil at the back of the patient's head. Sophisticated image processing, described in a companion paper, ensures that the user experiences maximum benefit from the small number of electrodes. This paper describes key features of this system.
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20
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Criteria employed by potential recipients considering adopting emerging visual technologies: The case of visual prostheses. HEALTH POLICY AND TECHNOLOGY 2014. [DOI: 10.1016/j.hlpt.2014.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Lewis PM, Ackland HM, Lowery AJ, Rosenfeld JV. Restoration of vision in blind individuals using bionic devices: a review with a focus on cortical visual prostheses. Brain Res 2014; 1595:51-73. [PMID: 25446438 DOI: 10.1016/j.brainres.2014.11.020] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 11/05/2014] [Accepted: 11/08/2014] [Indexed: 12/13/2022]
Abstract
The field of neurobionics offers hope to patients with sensory and motor impairment. Blindness is a common cause of major sensory loss, with an estimated 39 million people worldwide suffering from total blindness in 2010. Potential treatment options include bionic devices employing electrical stimulation of the visual pathways. Retinal stimulation can restore limited visual perception to patients with retinitis pigmentosa, however loss of retinal ganglion cells precludes this approach. The optic nerve, lateral geniculate nucleus and visual cortex provide alternative stimulation targets, with several research groups actively pursuing a cortically-based device capable of driving several hundred stimulating electrodes. While great progress has been made since the earliest works of Brindley and Dobelle in the 1960s and 1970s, significant clinical, surgical, psychophysical, neurophysiological, and engineering challenges remain to be overcome before a commercially-available cortical implant will be realized. Selection of candidate implant recipients will require assessment of their general, psychological and mental health, and likely responses to visual cortex stimulation. Implant functionality, longevity and safety may be enhanced by careful electrode insertion, optimization of electrical stimulation parameters and modification of immune responses to minimize or prevent the host response to the implanted electrodes. Psychophysical assessment will include mapping the positions of potentially several hundred phosphenes, which may require repetition if electrode performance deteriorates over time. Therefore, techniques for rapid psychophysical assessment are required, as are methods for objectively assessing the quality of life improvements obtained from the implant. These measures must take into account individual differences in image processing, phosphene distribution and rehabilitation programs that may be required to optimize implant functionality. In this review, we detail these and other challenges facing developers of cortical visual prostheses in addition to briefly outlining the epidemiology of blindness, and the history of cortical electrical stimulation in the context of visual prosthetics.
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Affiliation(s)
- Philip M Lewis
- Department of Neurosurgery, Alfred Hospital, Melbourne, Australia; Department of Surgery, Monash University, Central Clinical School, Melbourne, Australia; Monash Vision Group, Faculty of Engineering, Monash University, Melbourne, Australia; Monash Institute of Medical Engineering, Monash University, Melbourne, Australia.
| | - Helen M Ackland
- Department of Neurosurgery, Alfred Hospital, Melbourne, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
| | - Arthur J Lowery
- Monash Vision Group, Faculty of Engineering, Monash University, Melbourne, Australia; Monash Institute of Medical Engineering, Monash University, Melbourne, Australia; Department of Electrical and Computer Systems Engineering, Faculty of Engineering, Monash University, Melbourne, Australia.
| | - Jeffrey V Rosenfeld
- Department of Neurosurgery, Alfred Hospital, Melbourne, Australia; Department of Surgery, Monash University, Central Clinical School, Melbourne, Australia; Monash Vision Group, Faculty of Engineering, Monash University, Melbourne, Australia; Monash Institute of Medical Engineering, Monash University, Melbourne, Australia; F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, USA.
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22
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Vurro M, Crowell AM, Pezaris JS. Simulation of thalamic prosthetic vision: reading accuracy, speed, and acuity in sighted humans. Front Hum Neurosci 2014; 8:816. [PMID: 25408641 PMCID: PMC4219440 DOI: 10.3389/fnhum.2014.00816] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 09/24/2014] [Indexed: 11/13/2022] Open
Abstract
The psychophysics of reading with artificial sight has received increasing attention as visual prostheses are becoming a real possibility to restore useful function to the blind through the coarse, pseudo-pixelized vision they generate. Studies to date have focused on simulating retinal and cortical prostheses; here we extend that work to report on thalamic designs. This study examined the reading performance of normally sighted human subjects using a simulation of three thalamic visual prostheses that varied in phosphene count, to help understand the level of functional ability afforded by thalamic designs in a task of daily living. Reading accuracy, reading speed, and reading acuity of 20 subjects were measured as a function of letter size, using a task based on the MNREAD chart. Results showed that fluid reading was feasible with appropriate combinations of letter size and phosphene count, and performance degraded smoothly as font size was decreased, with an approximate doubling of phosphene count resulting in an increase of 0.2 logMAR in acuity. Results here were consistent with previous results from our laboratory. Results were also consistent with those from the literature, despite using naive subjects who were not trained on the simulator, in contrast to other reports.
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Affiliation(s)
- Milena Vurro
- Department of Neurosurgery, Massachusetts General Hospital/Harvard Medical School Boston, MA, USA
| | - Anne Marie Crowell
- Department of Neurosurgery, Massachusetts General Hospital/Harvard Medical School Boston, MA, USA
| | - John S Pezaris
- Department of Neurosurgery, Massachusetts General Hospital/Harvard Medical School Boston, MA, USA
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23
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Jung JH, Aloni D, Yitzhaky Y, Peli E. Active confocal imaging for visual prostheses. Vision Res 2014; 111:182-96. [PMID: 25448710 DOI: 10.1016/j.visres.2014.10.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 10/14/2014] [Accepted: 10/25/2014] [Indexed: 11/26/2022]
Abstract
There are encouraging advances in prosthetic vision for the blind, including retinal and cortical implants, and other "sensory substitution devices" that use tactile or electrical stimulation. However, they all have low resolution, limited visual field, and can display only few gray levels (limited dynamic range), severely restricting their utility. To overcome these limitations, image processing or the imaging system could emphasize objects of interest and suppress the background clutter. We propose an active confocal imaging system based on light-field technology that will enable a blind user of any visual prosthesis to efficiently scan, focus on, and "see" only an object of interest while suppressing interference from background clutter. The system captures three-dimensional scene information using a light-field sensor and displays only an in-focused plane with objects in it. After capturing a confocal image, a de-cluttering process removes the clutter based on blur difference. In preliminary experiments we verified the positive impact of confocal-based background clutter removal on recognition of objects in low resolution and limited dynamic range simulated phosphene images. Using a custom-made multiple-camera system based on light-field imaging, we confirmed that the concept of a confocal de-cluttered image can be realized effectively.
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Affiliation(s)
- Jae-Hyun Jung
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA
| | - Doron Aloni
- Department of Electro-Optics Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Yitzhak Yitzhaky
- Department of Electro-Optics Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Eli Peli
- Schepens Eye Research Institute, Massachusetts Eye and Ear, Harvard Medical School, Boston, MA, USA.
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24
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Ganesan K, Garrett DJ, Ahnood A, Shivdasani MN, Tong W, Turnley AM, Fox K, Meffin H, Prawer S. An all-diamond, hermetic electrical feedthrough array for a retinal prosthesis. Biomaterials 2014; 35:908-15. [PMID: 24383127 DOI: 10.1016/j.biomaterials.2013.10.040] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The interface between medical implants and the human nervous system is rapidly becoming more and more complex. This rise in complexity is driving the need for increasing numbers of densely packed electrical feedthrough to carry signals to and from implanted devices. This is particularly crucial in the field of neural prosthesis where high resolution stimulating or recording arrays near peripheral nerves or in the brain could dramatically improve the performance of these devices. Here we describe a flexible strategy for implementing high density, high count arrays of hermetic electrical feedthroughs by forming conducting nitrogen doped nanocrystalline diamond channels within an insulating polycrystalline diamond substrate. A unique feature of these arrays is that the feedthroughs can themselves be used as stimulating electrodes for neural tissue. Our particular application is such a feedthrough, designed as a component of a retinal implant to restore vision to the blind. The hermeticity of the feedthroughs means that the array can also form part of an implantable capsule which can interface directly with internal electronic chips. The hermeticity of the array is demonstrated by helium leak tests and electrical and electrochemical characterisation of the feedthroughs is described. The nitrogen doped nanocrystalline diamond forming the electrical feedthroughs is shown to be non-cyctotoxic. New fabrication strategies, such as the one described here, combined with the exceptional biostability of diamond can be exploited to generate a range of biomedical implants that last for the lifetime of the user without fear of degradation.
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25
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Baino F. How can bioactive glasses be useful in ocular surgery? J Biomed Mater Res A 2014; 103:1259-75. [DOI: 10.1002/jbm.a.35260] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 05/29/2014] [Accepted: 05/31/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Francesco Baino
- Institute of Materials Physics and Engineering, Applied Science and Technology Department; Politecnico di Torino, Corso Duca degli Abruzzi 24 10129 Torino Italy
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26
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Chow JPW, Chen N, Chung HSH, Chan LLH. Misalignment tolerable coil structure for biomedical applications with wireless power transfer. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:775-8. [PMID: 24109802 DOI: 10.1109/embc.2013.6609615] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Coil-misalignment is one of the major hurdles for inductively coupled wireless power transfer in applications like retinal prosthesis. Weak magnetic flux linkage due to coil misalignments would significantly impair the power efficiency. A novel receiver configuration with high misalignment tolerance is presented in this paper. The proposed receiver is composed of two receiver coils placed orthogonally, so as to reduce the variation of mutual inductance between transmitting and receiving coils under misalignment conditions. Three different receiver coil structures are analyzed and compared using the same length of wire. Theoretical predictions have been confirmed with measurement results.
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27
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Eiber CD, Lovell NH, Suaning GJ. Attaining higher resolution visual prosthetics: a review of the factors and limitations. J Neural Eng 2013; 10:011002. [PMID: 23337266 DOI: 10.1088/1741-2560/10/1/011002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Visual prosthetics is an expanding subfield of functional electrical stimulation which has gained increased interest recently in light of new advances in treatments and technology. These treatments and technology represent a major improvement over prior art, but are still subject to a host of limitations which are dependent on the manner in which one approaches the topic of visual prosthetics. These limitations pose new research challenges whose solutions are directly applicable to the well-being of blind individuals everywhere. In this review, we will outline and critically compare major current approaches to visual prosthetics, and in particular retinal prosthetics. Then, we will engage in an in-depth discussion of the limitations imposed by current technology, physics, and the underlying biology of the retina to highlight several of the challenges currently facing researchers.
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Affiliation(s)
- Calvin D Eiber
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia.
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28
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Seiler MJ, Aramant RB. Cell replacement and visual restoration by retinal sheet transplants. Prog Retin Eye Res 2012; 31:661-87. [PMID: 22771454 PMCID: PMC3472113 DOI: 10.1016/j.preteyeres.2012.06.003] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Revised: 06/19/2012] [Accepted: 06/23/2012] [Indexed: 12/18/2022]
Abstract
Retinal diseases such as age-related macular degeneration (ARMD) and retinitis pigmentosa (RP) affect millions of people. Replacing lost cells with new cells that connect with the still functional part of the host retina might repair a degenerating retina and restore eyesight to an unknown extent. A unique model, subretinal transplantation of freshly dissected sheets of fetal-derived retinal progenitor cells, combined with its retinal pigment epithelium (RPE), has demonstrated successful results in both animals and humans. Most other approaches are restricted to rescue endogenous retinal cells of the recipient in earlier disease stages by a 'nursing' role of the implanted cells and are not aimed at neural retinal cell replacement. Sheet transplants restore lost visual responses in several retinal degeneration models in the superior colliculus (SC) corresponding to the location of the transplant in the retina. They do not simply preserve visual performance - they increase visual responsiveness to light. Restoration of visual responses in the SC can be directly traced to neural cells in the transplant, demonstrating that synaptic connections between transplant and host contribute to the visual improvement. Transplant processes invade the inner plexiform layer of the host retina and form synapses with presumable host cells. In a Phase II trial of RP and ARMD patients, transplants of retina together with its RPE improved visual acuity. In summary, retinal progenitor sheet transplantation provides an excellent model to answer questions about how to repair and restore function of a degenerating retina. Supply of fetal donor tissue will always be limited but the model can set a standard and provide an informative base for optimal cell replacement therapies such as embryonic stem cell (ESC)-derived therapy.
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Affiliation(s)
- Magdalene J Seiler
- Department of Anatomy & Neurobiology, Reeve-Irvine Research Center, Sue & Bill Gross Stem Cell Research Center, University of California at Irvine, 1101 Gross Hall, 845 Health Science Rd., Irvine, CA 92697-4265, USA.
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