Implantable retinal prostheses are stimulation devices used to compensate for the light sensitivity loss of retinal cells. In this study, we propose and demonstrate a novel method to significantly reduce the setting time for the stimulation conditions of a retinal prosthesis chip capable of multi-electrode stimulation. The efficiency of the control method is increased while using only two wires, as in our previous work. The chip comprises an 8 bit ID and 7 electrodes, and the stimulation current value can be set from 50 to 1550 μA. The fabricated chip requires only 32 pulses to set the stimulation conditions, which is approximately 1/65 of that of our previous chip. Furthermore, it is equipped with a complementary metal–oxide–semiconductor rectifier to enable it to be driven by a rectangular AC power supply. The effectiveness of the chip is demonstrated by setting the stimulation conditions at approximately 18 μs per electrode at a clock frequency of 2.3 MHz.
In this paper, a miniature wireless system for use in conjunction with original lensless CMOS-based imaging devices is developed for in vivo imaging experiments. The system mainly comprises an image sensor, a microcontroller, and a Bluetooth Low Energy module for wireless data transmission. In addition to the hardware suitable for studies imposing freely-moving conditions, image sampling and processing features are implemented. Results demonstrate readiness for imaging in vivo, with adequate data transfer speed for a 12$\times$12-pixel region of interest with an area of 180$\times$180 \textmu m$^2$.
We developed implementation technologies for artificial vision devices compatible with suprachoroidal transretinal stimulation. We aimed to develop a device that can be safely implanted in the sclera of the eye for a long period. Using parylene C and bioceramics as biocompatible base materials, we realized a device with high in vivo safety by making the device structure flexible and reducing the wires of control signals. We successfully created a prototype device that combines a flexible wire structure based on a parylene C thin film with a wire-saving CMOS smart electrode structure based on CMOS integrated circuits. We conducted in vitro and in vivo experiments to confirm their performances. The immersion test confirmed that the device could work normally for four days. Furthermore, in the in vivo experiments using rat, we successfully measured evoked potentials in the brain induced by the stimulation current using the device.
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