A 1024-Channel CMOS Microelectrode Array With 26,400 Electrodes for Recording and Stimulation of Electrogenic Cells In Vitro

TLDR

The study aims to develop a high‑density CMOS microelectrode array that enables simultaneous, high‑resolution recording and stimulation of large neuronal ensembles. The array is fabricated on a single CMOS die, featuring 26,400 platinum electrodes with 17.5 µm pitch, 1,024 low‑noise readout channels, 10‑bit ADCs at 20 kS/s, and 32 stimulation units for current or voltage pulses. The device achieves 2.4 µVrms noise in the action‑potential band, 5.4 µVrms in the local‑field‑potential band, supports up to 78 dB gain, and operates at only 75 mW, eliminating the need for active cooling.

Abstract

To advance our understanding of the functioning of neuronal ensembles, systems are needed to enable simultaneous recording from a large number of individual neurons at high spatiotemporal resolution and good signal-to-noise ratio. Moreover, stimulation capability is highly desirable for investigating, for example, plasticity and learning processes. Here, we present a microelectrode array (MEA) system on a single CMOS die for in vitro recording and stimulation. The system incorporates 26,400 platinum electrodes, fabricated by in-house post-processing, over a large sensing area (3.85 × 2.10 mm2) with sub-cellular spatial resolution (pitch of 17.5 μm). Owing to an area and power efficient implementation, we were able to integrate 1024 readout channels on chip to record extracellular signals from a user-specified selection of electrodes. These channels feature noise values of 2.4 μVrms in the action-potential band (300 Hz-10 kHz) and 5.4 μVrms in the local-field-potential band (1 Hz-300 Hz), and provide programmable gain (up to 78 dB) to accommodate various biological preparations. Amplified and filtered signals are digitized by 10 bit parallel single-slope ADCs at 20 kSamples/s. The system also includes 32 stimulation units, which can elicit neural spikes through either current or voltage pulses. The chip consumes only 75 mW in total, which obviates the need of active cooling even for sensitive cell cultures.