Visual Prosthesis for Optic Nerve Stimulation
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The C-Sight visual prosthesis is based on optical nerve stimulation with a penetrating electrode array. A silicon-based microprobe by MEMS process techniques and Pt–Ir microwire arrays by electrochemical etching were fabricated in our project. Noise and impedance analyses were applied to optimize the electrode configuration. A multichannel microcurrent neural electrical stimulator and an implantable CMOS-based micro-camera were developed for neural stimulation and image acquisition, respectively, with a DSP-based system processing the captured image. Electrical evoked potentials (EEPs) from rabbit models were recorded using multichannel stainless-steel screws mounted on the primary visual cortex. The mean charge threshold density was 20.99 ± 5.52 μC/cm2 considering the exposed surface of the stimulating electrode. Current threshold decreased as the pulse duration of the stimulus increased while the corresponding charge threshold increased. The amplitude of P1 increased when the pulse duration increased from 0.4 to 1.0 ms while the latency of P1 changed little. Experiments also showed that different distribution maps of EEPs were elicited by different pairs of stimulating electrodes. The stimulating electrode pair along the axis of the optic nerve elicited cortical responses with much lower thresholds than that perpendicular to the axis of the optic nerve. The visual prosthesis with stimulating electrodes the penetrating into the optic nerve has been validated in animal experiments.
KeywordsOptic Nerve Recognition Accuracy Chinese Character Electrode Array Visual Evoke Potential
This research is supported by the National Basic Research Program of China (973 Program, 2005CB724302), National Science Fund for Distinguished Young Scholars from The National Natural Science Foundation of China (60588101), the National Natural Science Foundation of China (60871091), National Natural Science Foundation of China for the Youth (30700217), Shanghai Pujiang Program (07PJ14050), the 111 Project from the Ministry of Education of China (B08020).
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