A multichannel monolithic wireless microstimulator

A 64-site wireless current microstimulator chip (Interestim-2B) and a prototype implant based on this chip have been developed for neural prosthesis applications. Modular stand-alone architecture allows up to 32 such chips to be connected in parallel to drive 2048 sites. The only off-chip components are a receiver inductive-capacitive (LC) tank and microelectrode arrays such as silicon probes for intracortical stimulation. The implant receives inductive power and data at 2.5 Mb/sec from a frequency shift keyed carrier to generate up to 65800 stimulus pulses/sec. Each chip contains 16 current drivers with 270 μA full-scale current, 5-bit resolution, 100 MΩ output impedance, and a dynamic range that extends within 150 mV of the 5 V supply rail. The chip and implant (without probes) measure 4.6×4.6×0.5 and 19×14×6 (mm), respectively.