Contactless Electromagnetic Excitation of Conductive Microstructures for Resonant Sensors

In the present work a contactless excitation principle for resonators is proposed. The main interest is to develop an effective way to overcome the difficulties of activation of sensors in harsh or non-accessible environments. The investigated principle focuses on the vibrations and resonances contactless induced on structures by a time-variant external magnetic field. Our proposal is based on a fully passive sensing element without any specific magnetic properties that is simply required to be electrically conductive in a suitable frequency region. A simple theoretical model has been derived and has been verified and improved by means of FEM simulations. Experimentally, cantilever and a clamped-clamped beam miniaturized structures have been used as resonators to verify the theoretical expectations. To detect the vibrations, either piezoelectric and optical readout methods have been employed at present, with the aim of implementing a contactless electromagnetic readout method in the future.