Digital Resonance for MEMS

This work shows the application of pulsed digital oscillators to the detection of physical changes in MEMS devices that cause small shifts in their resonance frequencies. Such devices can be used as resonators in several sensor applications. According to this, a case study using a PDO structure to measure small concentrations of volatile organic gas compounds (VOCs) is introduced here. The MEMS devices used are cantilevers with a thin layer of polymer sensitive to the VOC concentration. Such devices have been simulated with the Coventor software to see the influence of the polymer layers on their mechanical responses. Finally, experimental measurements with various VOCs have been done, and results extracted from two PDO system sources, digital and analog, have been analyzed and compared.