This paper describes the technological developments underlying the realization of a reliable and reproducible microchip-based stimulator with a large number of stimulus electrodes. A microchip-based stimulator with over 500 electrodes for suprachoroidal transretinal stimulation (STS) is proposed in this paper, and an example is presented. To enhance reliability and reproducibility for such a large array, we introduce a flip-chip bonding technique and place microchips on the reverse side of a substrate. A square microchip of size 600 μm was fabricated using 0.35 μm standard CMOS process technology. Twelve microchips were flip-chip bonded on a polyimide substrate through Au bumps. To evaluate the feasibility of the proposed device, we successfully fabricated a stimulator with 12 microchips and 118 electrodes made of Pt/Au bumps, and demonstrated their operation in a saline solution for 2 weeks. Also, to evaluate the device operation in vivo, a stimulator with one active IrOx electrode was implanted into the scleral pocket of a rabbit and electrical evoked potential (EEP) signals with a threshold of 100 μA were obtained. We also fabricated a simulator with 64 microchips that has 576 electrodes (9 electrodes in a microchip times 64 microchips). © 2007 IOP Publishing Ltd.
CITATION STYLE
Ohta, J., Tokuda, T., Kagawa, K., Sugitani, S., Taniyama, M., Uehara, A., … Tano, Y. (2007). Laboratory investigation of microelectronics-based stimulators for large-scale suprachoroidal transretinal stimulation (STS). Journal of Neural Engineering, 4(1). https://doi.org/10.1088/1741-2560/4/1/S10
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