A 32-channel neural recording system with a liquid-crystal polymer MEA

Our integrated 32-channel recording system for in-vivo measurement of neural activity has 32 analog front-end (AFE) channels, a 32-to-1 time-division multiplexer, and a comparator-based cyclic ADC. Each channel has a low noise amplifier and a programmable-gain amplifier (PGA) with a tunable bandwidth. The mid-band gain of the low noise amplifier is 47 dB. The total gain of the analog front-end is adjustable from 54 dB to 67 dB, and its input-referred noise is 11.93 μV_rms. The low noise amplifier consumes 7.2 μW per channel. The comparator-based cyclic ADC digitizes the signals at 20 kS/s per channel, with a signal to distortion and noise ratio (SNDR) of 48.23 dB, corresponding to an effective number of bits (ENOB) of 7.72. This system was implemented in 0.18 μm CMOS technology, the average power consumption of the system is 62.5 μW per channel. An in-vivo measurement of the electrical activity of the cerebral cortex has been demonstrated, using a flexible liquid-crystal polymer microelectrode array.