Research Of Power And Data Wireless Transmission System For Visual Prosthesis

Vision is the most important mean to obtain information from the outside world. Blindness not only affects patients'life, study and work, but also brings heavy burden to the society. Any damage along the visual pathway causes blindness, such as retina, optic nerve and cortex. Although many researches have been taken place in photodynamics, genetic and pharmaceutical, so far there are no effective therapies in curing blindess, especially as to diseases like Retinitis Pigmentosa(RP) and Age-related Macular Degeneration (AMD). Visual protheses based on functional electrical stimulation have been brought to great attention over the past decades, which could be a potential solution to blindness.Visual protheses are artificial organs which replace the funtion of retina to restore visual function. The exteranl system of visual prothesis collects and processes the optical information, and the internal system activates nerve cells by microcurrent according to the command from the external one. The normal function of internal system needs stable power supply and realtime communication with the external one. Wireless link is choosed because it gets rid of infection risk and inconvenience to patients caused by conductive wire connection, and it meets the wholly implantable demand of visual prothesis. Therefore, the wireless link between the exteranl and internal system is an key component of visual prothesis.This paper introduced the telemetry systems of several foreign research groups, discussed the principle of power and data wireless transmission, and analyzed the demand and challenges of telemetry system of visual prothesis. Based on micro-stimulator CI0902 made by our cooperation group, we developed a telemetry system utilizing a RFID chip EM4094, which achieved the power and data transmission by a single couple of coils. Meanwhile, we set up and tested the whole system from image processing unit to micro-stimulator output. The test showed that the telemetry system sufficiently supported the whole system. In addition, we designed another telemetry system based on Class E power amplifier against the disadvantages of prior system. An experimental system was implemented with an efficiency up to 30% and a non-return to zero encoding(NRZ) transfer rate of 1M bps at the distance of about 6mm between coils. Finally, some improving suggestion is given to the unfinished and defective issues in this paper.