Testing And Evalution Of Vision Prosthesis Stimulator With Wireless Energy And Data Transmission

Human vision is an important way to understand the objective world. For various reasons, the lesions or injury of the visual pathway can lead to blindness, about 25% of the blind due to retinal diseases. Retinal diseases such as age-related macular degeneration and retinitis pigmentosa are not curable. With the development of biomedical, materials science, microelectronics and other disciplines, the nerve prostheses, which can replace and control the diseased organs and tissues, have become the focus of the research to restore the vision of the blindness.Visual prosthesis is an artificial device for visual rehabilitation, such device gathers the outside image information, and encodes the information. Micro-current signals driven by micro-current stimulator will be loaded into the visual nervous system through the microelectrode array, in order to produce phosphene in the visual center, achieve restoration of visual function. The core of the visual prosthesis is a microelectronic integrated circuit chip, the chip provides the retina, optic nerve and visual cortex of the electrical stimulation signal, and the chip is often called "visual prosthesis stimulator."This paper analyzes the implant stimulation of foreign research groups, discusses the challenges and future trends of the visual prosthesis stimulator. Based on our research, we developed a stimulator for neural stimulation system.In our design scheme, the current stimulation chip provides 17 stimulation electrodes with accurate current pulse, has certain data error detection capability, data encoding algorithm can meet certain requirements. To make the chip to work by wireless means, we designed a rectifier filter circuit, clock and data recovery circuit.The front-end transmission circuit uses the chip EM4094 and C8051F410 microcontroller chip to build code and modulation circuit. Coupled through the coil, energy and data transmission uses the same coil. Receiving circuit obtains the power from the rectifier and filter circuit, and demodulates the clock and data frames from the signal, the micro-current electrical stimulation pulses generated by the chip according to the data frame which contains the information required for two-phase pulse output. In order to test the performance of stimulator chip, we use circuit to send different data frame, make the stimulator chip get different pulse amplitude and width parameters, then we can obtained the output pulse amplitude and width of the stimulator chip with different parameters. From the results of the experiment, the output pulse amplitude and input parameters have good linear relationship, the output pulse amplitude range from 0 to 2mA, and the output pulse width is lesser, the maximum value is about 62μs, limits the stimulator stimulation intensity.