Single-chip CMOS capacitive gas sensor for detection of volatile organic compounds

We present interface circuitry for a novel CMOS gas detection system based on a capacitive microsensor for the detection of airborne volatile organic compounds (VOCs). The system achieves an accuracy more than 18 bits at a bandwidth of 0.7 Hz, which corresponds to a detection limit of, e.g., 2 ppm for ethanol. The system does not any need accurate external voltage or current references and includes a serial interface (I/sup 2/C-bus) to set the parameters and transmit the acquired data to an external data processing unit.