A Fringe Field Shaping CMOS Capacitive Imaging Array

While classical electrochemical impedance spectroscopy (EIS) focuses on measurements from a single working electrode, dense active microelectrode arrays offer opportunities for new modes of sensing. Here we present experimental results with an integrated sensor array for electrochemical imaging. The system uses a 100 × 100 custom CMOS electrode array with 10 µm × 10 µm pixels, which measures impedance at frequencies up to 100 MHz. The sensor chip is uniquely designed to take advantage of the electrostatic coupling between groups of nearby pixels to re-shape the local electric field. Multiple bias voltages and clock phases create new types of signal diversity that will enable enhanced sensing modes for computational imaging and impedance tomography.