Acoustic Wave Generation and Detection in Non-Piezoelectric High-Q Resonators

Acoustic sensing is traditionally based on the piezoelectric effect and thus limited in the selection of transducer materials and options for sensor fabrication. Another excitation method is the principle of magnetic direct generation of acoustic waves, which has been employed for non-destructive evaluation (NDE) of materials as electromagnetic-acoustic transducer (EMAT) sensors for several decades. With a suitable high-Q mechanical resonator the lower transduction efficiency can be overcome. The advantages of remote excitation, i.e., inexpensive fabrication of many different resonator materials and a wide variety of possible vibration modes, can be utilized to suit the specific needs of an application. Latest developments concentrate on the characterization of different excitation setups to generate and compare different modes of vibration.