Title:Electromagnetic-Acoustic Resonators for Remote, Multi-Mode Solid and Liquid Phase SensingAuthor(s):Frieder LucklumAbstract:Electromagnetic excitation of acoustic resonator sensors is a unique method alternative to piezoelectric and electrostatic excitation. Based on electro-magnetic-acoustic transducers, the continuous, resonant operating mode of these sensors offers distinctive advantages and possibilities, which have only recently been demonstrated. Sensor element and excitation as well as detection circuitry can be spatially separated. Only conductive materials or layers are required, and the mechanical forces can be impressed in a variety of directions. This results in multiple degrees of freedom, which allows the excitation and detection of fundamentally different modes of vibration in the resonator element. This multi-mode operation leads to the possibility to measure multiple physical properties in terms of their acoustic load with no or minimal changes to the sensor setup. In this work, the theory behind this method has been investigated. Suitable models and simulations have been derived in order to explain and predict measurement results. Three different resonator devices have been fabricated and analyzed for modes of flexural and shear vibration. Here, the focus has been put on simple micromachined silicon membranes and inexpensive aluminum and brass plates. Suitable vibration modes were utilized for mass detection, liquid property sensing, and liquid level measurements as a proof of concept for the multi-mode sensor principle. Additionally, prototype metal resonator arrays were used to demonstrate simultaneous measurement of different physical properties.Publishing:4/2010