Self Calibrated Readout Frontend for Capacitive Biosensors

In capacitive transducers area, the fabrication process variations in the parameters that define the nominal capacitance induce mismatch between the fabricated transductors; and in order to minimize it a new frontend architecture, that does not need a reference sensor for calibration, is presented here. The proposed system works with a DC reference signal, instead of an AC signal as most of the reported works. A readout system using the proposed architecture was designed in a 180nm CMOS technology for a particular capacitive microfluidic bio-sensor to detect E.Coli bacteria. The nominal sensor has a capacitance range that goes from 192pF to 122 pF for a 0-100,000 UFC/ml concentration range.