A high-output-impedance current microstimulator for anatomical rewiring of cortical circuitry

This paper reports on the design, implementation, and performance characterization of a high-output-impedance current microstimulator fabricated using the TSMC 0.35 mu m 2P/4M n-well CMOS process as part of a fully integrated neural implant for reshaping long-range intracortical connectivity patterns in an injured brain. It can deliver a maximum current of 94.5 mu A to the target cortical tissue with current efficiency of 86% and voltage compliance of 4.7V with a 5-V power supply. The stimulus current can be programmed via a 6-bit DAC with an accuracy better than 0.47 LSB. Stimulator functionality is also verified with in vitro experiments in saline using a silicon microelectrode with iridium oxide (IrO) stimulation sites.