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Samir Damle, Yu-hsin Liu, Yi Jing, William R Freeman, Yu-Hwa Lo; Evaluating the Effective Spatial Resolution of an Optoelectronic Nanowire Prosthesis. Invest. Ophthalmol. Vis. Sci. 2017;58(8):4185.
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© ARVO (1962-2015); The Authors (2016-present)
We characterized the effective spatial resolution of a high-density optoelectronic nanowire detector array for retinal prosthesis by measurements and simulations.
Scanning electrochemical microscopy techniques were used to characterize the spatial distribution of electric potential produced by nanowire p/n junction detectors with iridium oxide electrodes in electrolyte. Electric potential measurements were performed with a potentiostat in x-y planes above active electrodes. Effective spatial resolution was evaluated from the relative change of electric potential for different pixels under the condition that only one single pixel is illuminated by a laser beam.
The optoelectronic nanowire detector array produces spatially resolvable focal stimulation under global electrical bias and focal illumination. The “dark current” produced by simultaneous biphasic electrical bias of all dark electrodes results in a nearly constant baseline potential (±3%). Illumination of a single electrode results in focal photocurrent that achieves 3:1 contrast between the illuminated pixel and the neighboring pixels that are 50µm or further away. Simulation results are consistent with the experimental observations and produce results with more complicated illumination patterns.
Spatial resolution is a critical metric to evaluate retinal prosthesis effectiveness. Prostheses available on the market today lack sufficient electrode density to achieve significant visual acuity in patients. We characterized the effective spatial resolution of a high-density nanowire detector array. Single pixel resolution for a nanowire electrode array is effectively preserved at electrical currents and penetration depths relevant for subretinal stimulation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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