Single-chip wireless microsystems for multichannel neural biopotential recording

This project has developed single-chip low-power wireless microsystems, fabricated using a 1.5-mum double-poly double-metal n-well standard CMOS process, that can be used with micromachined recording microelectrode arrays for interfacing with the nervous system at the cellular level in unrestrained biological hosts.; In particular, an ultralight 2-channel hybrid backpack telemeter is developed for muscle biopotential recording in small insects. It dissipates 2mW of power from a 3-V power supply, weighing only 0.74g (including two miniature batteries) that is light enough to be carried by air-borne moths. This system has been successfully employed for wireless in vivo recording of EMG biopotentials in a male giant sphinx moth Manduca Sexta over a transmission range of ∼2m.; Two wireless battery-powered recording systems-on-a-chip (SOC) for multichannel neural interfacing have been developed that combine ac amplification, dc baseline stabilization, clock generation, time-division multiplexing, and wireless FM transmission of muV- and mV-range input biopotentials on chips interfaced with only three off-chip components. The 4-channel recording device measures 1.7 x 1.2 x 0.16cm3 and weighs 1.1g including two miniature batteries whereas the 8-channel recording system measures 2.1 x 2.1 x 0.16cm3 and weighs 2.2g. They dissipate <2.2mW from a 3-V power supply, which is the lowest total power consumption yet reported. The systems electrical characteristics have been fully characterized via benchtop and in vitro tests in saline using two different neural recording microelectrodes. Successful single-channel wireless in vivo recordings of neural activity in the auditory cortex of an awake marmoset monkey have been performed at 96.2MHz at several transmission ranges up to 0.5m with measured SNR >8.4dB.; Finally, a telemetry command receiver integrated with a multichannel neural recording transmitter is developed for wireless site selection and site monitoring within a 4.6 x 4.6-mm2 bi-directional biotelemetry chip. The receiver is designed to select seven recording sites from a total of 28 available sites according to four pre-defined site selection patterns and to perform power management via a 1-MHz Manchester-encoded ASK link. Detailed system simulation results together with preliminary measurement results from a fabricated prototype receiver are presented.