Noise-immune current-integration-based CMOS amperometric sensor platform with 1.2 μm × 2.05 μm electroless-plated microelectrode array for robust bacteria counting

A noise-immune current-integration-based CMOS amperometric sensor platform with a bacteria-sized (1.2 μm × 2.05 μm) Au electroless-plated microelectrode array for robust bacteria counting is presented. For robust bacteria counting with sufficient signal-to-noise ratio (SNR), noise must be reduced because the bacteria-sized microelectrode surrounded by a wall can handle only small current (on the order of 100 pA). This is the first platform to employ a current integrator in conjunction with a bacteria-sized microelectrode array. As a result of the proposed current integration, noise associated with drift and the CMOS sensor array can be reduced. To verify the effectiveness of the proposed approach, a test chip was fabricated using 0.6 μm standard CMOS technology. Measurement results demonstrate successful high-sensitivity 2D direct counting of microbeads (1 μm diameter) with 27 dB SNR at 5-ms integration time.