COMBINED VAPOR AND/OR GAS CONCENTRATION SENSOR AND SWITCH

A combined vapor and/or gas concentration sensor and switch includes a resonating structure having a first side with a functionalized surface and a second side opposite the first side, a first resonant frequency of a first vibration mode, and a third resonant frequency of a third vibration mode. A direct current bias source is coupled to the resonating structure. A first AC voltage source is coupled to the drive electrode and provides the resonating structure, via the drive electrode, with a first voltage having an amplitude causing the first vibration mode of the resonating structure to exhibit a pull-in band and having a frequency adjacent the pull-in band of the first mode. A second AC voltage source is coupled to the drive electrode and provides the resonating structure, via the drive electrode, with a second voltage having a frequency corresponding to the third resonant frequency. A read-out circuit is coupled to the sensing electrode and is configured to determine a vapor and/or gas concentration based on a difference between the frequency of the second voltage supplied by the second AC voltage source and a frequency obtained by the read-out circuit.