Reasearch Of Control And Feedback Systems For Stimulator Of Vision Prosthesis

Vision prosthesis is aiming at helping the blind to restore vision by stimulating tissue with micro current stimulation. The ultimate goal of vision prostheses is to artificially produce a visual perception in individuals with profound loss of vision due to disease or injury that can be used to perform activities for which current assistive technologies have severe limitations; such activities include reading text, recognizing faces, and negotiating unfamiliar spaces.Micro stimulator is to change digital image information to analog stimulation current in the vision prostheses. It is functionally between image processing system and stimulation electrodes. The working status of micro stimulator is important to the characters of stimulation current, such as effect, safety and real-time. Furthermore, Device-tissue interactions begin with insertion and continue as cells in the immediate vicinity of the inserted device respond to the insults provided by insertion. These interactions result in pathological changes of tissues and morphological changes of electrodes. These changes will finally affect some stimulation parameters, such as tissues structure, threshold of excitation and morphology of electrodes. Therefore, a feedback system is needed to collect the status information of device and tissue so that stimulators can response of those changes as described above.In this article, we analyze the structure of stimulators of other research groups, and develop our control system and feedback system of stimulator in our optic nerve prosthesis. The feedback system is based on in-vivo impedance measurement of electrode-optic nerve. We also obtain and analyze the impedance of electrode-optic nerve with this feedback system in animal experiments.The basic theory of electrode-optic nerve electrochemical process and the equivalent electrical circuit were studied in this paper, and thereafter proposed the precise three-electrode system to test the electrode-optic nerve union impedance, based on which, we construct the feedback system of optic-nerve prosthesis.