Vertically aligned extracellular microprobe arrays/(111) integrated with (100)-silicon mosfet amplifiers

Abstract

We report a heterogeneous integration of vertically aligned extracellular micro-scale silicon (Si)-probe arrays/(111) with MOSFET amplifiers/(100), by IC processes and subsequent vapor-liquid-solid (VLS) growth of Si-probes. To improve the extracellular recording capability of the microprobe with a high impedance of > 1 MΩ at 1 kHz, here we integrated (100)-Si source follower buffer amplifiers by ~700°C VLS growth compatible (100)-Si MOSFET technology. Without on-chip source follower, output/input signal ratio of the microprobe in saline was 0.59, which was improved to 0.72 by the on-chip source follower configuration, while the signal-to-noise ratio (SNR) was improved to 12.5 dB in the frequency of extracellular recording. These results indicate that the integration of the source follower buffer amplifiers becomes a powerful way to enhance the performance of high impedance microprobe electrodes in neural recordings.