Contactless Excitation of MEMS Resonant Sensors by Electromagnetic Driving

M. Baù[1], V. Ferrari[1], and D. Marioli[1]
[1]Department of Electronics for Automation, University of Brescia, Brescia, Italy

A contactless electromagnetic principle for the excitation of mechanical vibrations in resonant structures has been investigated. The principle relies on no specific magnetic property of the resonator except electrical conductivity and can be adopted for employing the structures as resonant sensors for measurements either in environments not compliant with the requirements of active electronics or in limited accessibility environments. An external coil is employed as an excitation source which inductively couples to the conductive surface of the resonator or to a secondary coil connected to conductive paths on the resonant structure. Preliminary tests on miniaturized resonators have been performed, namely cantilevers and clamped-clamped beams. The principle has been subsequently implemented in the design of MEMS resonators. Experimental verifications have shown the possibility of contactless exciting microresonators over short-range distances.