Wireless charge recovery system for implanted electroencephalography applications in mice

Recording electroencephalography (EEG) in multiple mice within one cage is needed not only to allow high throughput testing, but to also maintain normal social and behavioral cues when studying sleep, memory and psychiatric disorders. This work proposes a concept and a blueprint of implementation of a low-power, untethered, fully integrated, implantable system suitable for EEG applications. The system employs two primary components of i) wireless powering through Helmholtz coil around the cage and ii) charge recovery logic (CRL) instead of traditional static CMOS for EEG processing. CRL presents lower power consumption, especially in the low-frequency range typical of EEG. The presented system uses charge recovery principles for the analog circuits as well, enabling improved power savings with respect to existing solutions. Finite element method simulations, or FEM, shows the feasibility of power transmission over a inductive wireless link, designed with the Helmholtz coil over the cage. The roadmap for implementation is described in the system implementation blueprint, identifying the individual building blocks that have been shown to be functional, and shown to be inter-operable with simulations in this work.