A wireless microsystem with digital data compression for neural spike recording

The paper describes a multi-channel neural spike recording system sensing and processing the action potentials (APs) detected by an electrode array implanted in the cortex of freely-behaving small laboratory animals. The core of the system is a custom integrated circuit (IC), with low-noise analog front-end interfaced to a 16 electrode array followed by a single 8-bit SAR ADC, a digital signal compression and a 400-MHz wireless transmission units. Data compression is implemented by detecting action potentials and storing up to 20 points per each spike waveform. The choice greatly improves data quality and allows single spike identification. The transmitter delivers a 1.25-Mbit/s data rate coded with a Manchester-coded frequency shift keying (MC-FSK) within a 3-MHz bandwidth. An overall power consumption of 17.2 mW makes possible to reach a transmission range larger than 20-m. The IC is mounted on a small and light printed circuit board. Two AAA batteries, set in a pack positioned on the back of the animal, power the system that can work continuously for more than 100 h.