Design and fabrication of a MEMS capacitive chemical sensor system

This paper describes the development of a MEMS sensor system to detect volatile compounds. The sensor consists of a MEMS capacitive sensor element monolithically integrated with a sensing circuit. The sensor element is a parallel plate capacitor using a chemically sensitive polymer as the dielectric. In presence of the target analyte, the polymer swells and changes the capacitance of the sensor element. This change in capacitance is sensed and converted to a digital bit stream by a delta-sigma sensing circuit. This paper provides an overview of the design of the sensor element, the sensing circuit and the process integration for their fabrication on a single die