A silicon microelectrode array for simultaneous recording and stimulation in the brain of behaving animals

This paper presents an eight-channel silicon neural probe with integrated CMOS circuitry designed for simultaneous recording and stimulation in the brain. The probe includes eight on-chip amplifiers that can be individually bypassed, allowing direct access to the indium sites for electrical stimulation. The on-probe amplifiers have a gain of 38.9dB, an upper cutoff frequency of 9.9 kHz, and an input referred noise of 9.2 μVrms from 100 Hz to 10 kHz. The low-frequency cutoff of the amplifier is tunable to allow the recording of field potentials and minimize stimulus artifact. The on-probe circuitry consumes 672 μW from ±1.5 V supplies and occupies 2.02 mm² in 3 μm features. In-vivo recordings have shown that the preamplifiers can record single-unit activity 1 ms after the onset of stimulation on sites as close as 20 μm to the stimulating electrode. Further artifact suppression is achievable with precise tuning of the low-frequency amplifier cutoff.