A novel method for monitoring mass-change response of piezoelectric-excited millimeter-sized cantilever (PEMC) sensors

We show that monitoring impedance at a fixed frequency near resonant frequency of a piezoelectric-excited millimeter-sized cantilever (PEMC) sensor provides equivalent measurement as the conventional approach of monitoring resonant frequency. Two sensing experiments are used to validate the proposed approach: density change and detection of a pathogen (E. coli O157:H7). The impedance approach is feasible because PEMC sensors exhibit modest Q-values of 30-60 at similar to 900 kHz and typical biosensing response falls well below 5 kHz. a frequency band near resonant frequency where impedance is a linear function of frequency. The simpler impedance approach lends itself to high throughput applications where large number of sensor responses is to be monitored simultaneously. (C) 2009 Elsevier B.V. All rights reserved.