Mobility performance with a pixelized vision system

Cha, Kichul; Horch, K.W.; Normann, Richard A.

doi:10.1016/0042-6989(92)90229-c

Cited by 216 publications

(158 citation statements)

References 21 publications

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“…[40][41][42] At the same time stimulation charge must be high enough to traverse the retina and reach spiral ganglions giving that charge delivery requirements sets a lower limit for electrode density and thereby pixel density of the vision system. Reasonable size for a retinal implant is around 3 ϫ 3 mm 2 ͑the fovea diameter is ϳ1.5 mm͒ so 625 electrodes could be fit into the implant if electrode diameter is less than 100 m. Keeping in mind that the diameter of ganglion cells is in the range 10-20 m, 43 diameters in the range 25-100 m seem reasonable even though the smaller diameter would be preferred for higher resolution.…”

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confidence: 99%

Composite biomolecule/PEDOT materials for neural electrodes

2008

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Electrodes intended for neural communication must be designed to meet both the electrochemical and biological requirements essential for long term functionality. Metallic electrode materials have been found inadequate to meet these requirements and therefore conducting polymers for neural electrodes have emerged as a field of interest. One clear advantage with polymer electrodes is the possibility to tailor the material to have optimal biomechanical and chemical properties for certain applications. To identify and evaluate new materials for neural communication electrodes, three charged biomolecules, fibrinogen, hyaluronic acid (HA), and heparin are used as counterions in the electrochemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The resulting material is evaluated electrochemically and the amount of exposed biomolecule on the surface is quantified. PEDOT:biomolecule surfaces are also studied with static contact angle measurements as well as scanning electron microscopy and compared to surfaces of PEDOT electrochemically deposited with surfactant counterion polystyrene sulphonate (PSS). Electrochemical measurements show that PEDOT:heparin and PEDOT:HA, both have the electrochemical properties required for neural electrodes, and PEDOT:heparin also compares well to PEDOT:PSS. PEDOT:fibrinogen is found less suitable as neural electrode material.

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confidence: 99%

Composite biomolecule/PEDOT materials for neural electrodes

2008

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“…In order to obtain better vision through a retinal prosthesis, over 1,000 electrodes would be preferable [8]. When increasing the number of electrodes, we are faced with problems associated with the interconnection between electrodes and external lead wires with good mechanical flexibility.…”

Section: Interconnectionmentioning

confidence: 99%

Stimulator Design of Retinal Prosthesis

Ohta

Noda

Shodo

et al. 2017

IEICE Trans. Electron.

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SUMMARY This study focuses on the design of electrical stimulator for retinal prosthesis. The stimulator must be designed such that the occurrence of electrolysis or any irreversible process in the electrodes and flexible lead is prevented in order to achieve safe stimulation over long periods using the large number of electrodes. Some types of biphasic current pulse circuits, charge balance circuits, and AC power delivery circuits were developed to address this issue. Electronic circuitry must be introduced in the stimulator to achieve the large number of electrodes required to obtain high quality of vision. The concept of a smart electrode, in which a microchip is embedded inside an electrode, is presented for future retinal prostheses with over 1000 electrodes.

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“…Similarly, head tracking would not significantly improve scanning performance (Chung, 1992;Ehrlich & Singer, 1994). However, for a more complex task such as physical navigation, these factors of presence may significantly affect the mobility performance of the subject (Cha, Horch, & Normann, 1992;Zenyuh, Reising, Walchi, & Biers, 1988), and should be considered for future navigational studies.…”

Section: Subjectmentioning

confidence: 99%

Testing Visual Search Performance Using Retinal Light Scanning as a Future Wearable Low Vision Aid

Lin¹,

Seibel²,

Furness³

2003

International Journal of Human-Computer Interaction

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For the goal of designing a wearable low vision aid, aspects of both head-mounted display (HMD) design and performance evaluation were integrated into a single study of scanning ability. A head-mounted version of a novel retinal light scanning display known as the virtual retinal display was fabricated for this study. A remote head CCD (charge coupled device) attached approximately at the user's line of sight was used as the input source. Scanning ability was quantified as the time to identify a target in a wide field of distractors while using the HMD design in four different display interface modes (DIMs). Each DIM was tested with respect to their corresponding controls: A (augmented, see-through) and CO (center occluded) DIMs were compared to the augmented control (augmented, retinal display turned off), and CPO (center and periphery occluded) and PO (periphery occluded) DIMs were compared to the periphery occluded control (periphery obstructed, retinal display turned off). Each DIM was tested at high, medium, and low contrast levels. Five subjects were tested without optical correction (visual acuity worse than 20/200), which accurately represented low vision subjects. Results showed that for each DIM, scanning performance decreased as the contrast level decreased. At the INTERNATIONAL JOURNAL OF HUMAN-COMPUTER INTERACTION, 15(2), 245-263 Copyright © 2003, Lawrence Erlbaum Associates, Inc.We thank Nick Kipping (student in Industrial Design) and Robert Burstein (Research Engineer) for their technical assistance, Duff Hendrickson (Experience Designer) for the computer animations, The National Science Foundation for funding this research (Grants 9801294 & 9978888), the R.E.U. program, and The Mary Gates Foundation for financial assistance.Sun-Kai V. Lin is now at the Department of Bioengineering, University of Pennsylvania. Requests for reprints should be sent to Sun-Kai V. Lin, Department of Bioengineering, University of Pennsylvania, 120 Hayden Hall, 3320 Smith Walk, Philadelphia, PA 19146. E-mail: sklin@ seas.upenn.edu lowest contrast level, the PO DIM provided the greatest and most significant improvement in scanning performance. At the medium and highest contrast levels, all DIMs provided equal or worse performance than their controls. Additionally, the subjects' natural visual acuity showed no correlation with scan time. All subjects reported a higher acuity with the retinal display, and showed a diverse range of preference for the most helpful DIM. Based on these results, we realized that low vision applications have unique design requirements unlike those for normally sighted users, and therefore customization of a wearable low vision aid may be an optimal design strategy.

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Mobility performance with a pixelized vision system

Cited by 216 publications

References 21 publications

Composite biomolecule/PEDOT materials for neural electrodes

Composite biomolecule/PEDOT materials for neural electrodes

Stimulator Design of Retinal Prosthesis

Testing Visual Search Performance Using Retinal Light Scanning as a Future Wearable Low Vision Aid

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