A 16×20 electrochemical CMOS biosensor array with in-pixel averaging using polar modulation

摘要

Biosensors based on electrochemical impedance spectroscopy (EIS), an ultra-sensitive, label-free sensing technique, are a promising technology for precise and rapid disease diagnosis at the point-of-care (POC). However, EIS usually requires mixers and lock-in detection to measure both the magnitude and phase of the complex impedance. To address this issue, we report a 16×20 electrochemical biosensor array with on-chip sensors that implements a polar-mode measurement method that allows the readout circuitry to be mostly digital and small enough to fit within a 140×140 μm^{2pixel. The architecture enables in-pixel digitization and accumulation, which increases the SNR by 10 dB for each 10× increase in readout time. Implemented in a 0.18 μm process, the 3×4 mm2chip achieves state-of-the-art performance with an rms phase error of 0.04% at 50 kHz and was used to measure hybridization of Zika virus oligonucleotides.}