A Power-Efficient Switched-Capacitor Stimulating System for Electrical/Optical Deep Brain Stimulation

A power-efficient wireless switched-capacitor based stimulating (SCS) system for electrical/optical deep brain stimulation (DBS) is presented. The SCS system efficiently charges storage capacitors directly from an inductive link and delivers accurately balanced charge to the tissue, improving the overall stimulator efficiency. In addition, the decaying exponential stimulus pulses generated by SCS can be more effective than conventional rectangular and ramp stimuli in activating neural tissue when consuming the same amount of energy, leading to higher stimulus efficacy. A 4-channel wireless SCS system in 0.35 μm CMOS process achieves stimulator efficiency of 80.4% with capacitor pairs charged to ±2V, while the decaying exponential stimulus requires equal or less stimulus energy and injected charge than other stimuli depending on pulse width to activate the same tissue area. The SCS system has also been utilized for power-efficient wireless optogenetic stimulation by periodically discharging capacitors into high-current micro-LED arrays. Results from acute in vivo experiments have verified the utility of the SCS system prototype in both electrical and optical stimulation.