Persistence of bending and torsional modes in piezoelectric-excited millimeter-sized cantilever (PEMC) sensors in viscous liquids-1 to 103 cP

Cantilever sensors consisting of only a piezoelectric layer express both bending and torsional modes near similar to 25 kHz that persist with reasonable Q-values (similar to 15) in liquids of high viscosity (>100 cP). Responses of both bending and torsional modes in liquids (1 1019 cP) were measured simultaneously. The bending mode response was more sensitive to mass-change effects than the torsional mode, and the response in liquids <70 cP matched theoretical values within 0.9%. At 1019 cP the bending mode response was within 10.4% of theory. The bending and torsional modes in PEMC can potentially be used simultaneously for bio-chemical sensing in very viscous samples. (C) 2011 American Institute of Physics. [doi:10.1063/1.3554677]