Multi-mode excitation of electromagnetic-acoustic resonant sensor arrays

Electromagnetic excitation of acoustic sensors as an alternative to piezoelectric and capacitive excitation allows for non-contact measurements and the generation of multiple modes of vibration. It is possible to utilize the same excitation setup to excite flexural, face shear, and thickness shear modes with no changes to the resonator itself. In this contribution we propose a sensor array setup to take advantage of this unique property. We will demonstrate the possibility of simultaneously exciting similar and different vibration modes in the different array elements. This allows for increased redundancy in experimental measurement and the simultaneous determination of multiple properties, e.g. viscosity, density, liquid volume in a single measurement. As a proof of concept, we have fabricated a metal sensor array on 100 mum thick brass sheets. We will present experimental results and a comparison of sensor arrays to single elements for measurements in liquids at different densities and viscosities.