High Efficiency Wireless Power Transmission with Digitally Configurable Stimulation Voltage for Retinal Prosthesis

Electrical stimulation of retinal neuron cells has been used to invoke perception of sight in legally blind patients due to loss of photoreceptors. In such a prosthetic device, one of the challenges is that the required stimulation voltage varies among patients and also over time. The voltage supply to the stimulator circuits should adapt to these changes for optimal device operation. This paper presents a closed loop wireless power transmission system, which can digitally adjust the voltage. In the system, power is wirelessly transmitted to the secondary side (implant) through a magnetically coupled coil pair. The secondary side wirelessly transmits information about the recovered voltage back to the primary side, which accordingly adjusts the amount of power transmitted and thus maintains the voltage in the implant at the required value. Experimental results verify that the voltage can be effectively configured with power savings up to 30%