A Multimodal Multichannel Neural Activity Readout IC with 0.7μW/Channel Ca2+-Probe-Based Fluorescence Recording and Electrical Recording

This paper presents a multimodal multichannel neural activity readout IC which can perform not only the electrical recording (ER) but also the fluorescence recording (FR) of neural activity for the cell-type-specific study of heterogeneous neuronal cell populations. The time-based FR circuit senses Ca²⁺ concentration using Ca²⁺ probes while the ER circuit acquires action potentials (APs) and local field potentials (LFPs). The IC is fabricated in 0.18μm CMOS. The FR circuit achieves a recording range of 81dB (75pA to 860nA) and consumes the power of 0.7μmW/Ch. The ER circuit achieves the input-referred noise (IRN) of 2.7μm Vrms over the bandwidth (BW) of 10kHz, while consuming the power of 4.9μmW/Ch. The in-vitro measurement is performed for recording Ca²⁺ concentration and electrical neural signals.