Frequency profile measurement system for microcantilever-array based gas sensor

This paper presents an autonomous instrument based on an array of 8 MEMS micro cantilevers for gas sensor application. The main contribution of this system to the MEMS domain lies on the way the micro cantilevers are optimally exposed to a constant gas flow in a gas cell where the electrical connections to the sensors are done without any wire-bonding. Sensors can therefore be easily changed for another application or for maintenance. Moreover, this complete and autonomous system is able to extract in real time (1 reading/sec) the frequency response of all the MEMS cantilevers by using an innovative mixed-signal processing circuit featuring self-diagnostic and automatic-calibration. Other novelties are the simultaneous piezo-electric excitation of the sensor-array, a low-noise polarization circuit and the detection circuit optimized for piezo-resistive micro cantilevers. From a system point of view this instrument provides the ability to monitor the frequency profiles of an array of resonant gas sensors.