Mass-change sensitivity of high-order mode of piezoelectric-excited millimeter-sized cantilever (PEMC) sensors: Theory and experiments

We show that mass-change sensitivity predicted from first principles model of piezoelectric-excited millimeter-sized cantilever (PEMC) sensors is in reasonable agreement with previously reported experimental values. We introduce a new attogram-level mass addition calibration method using 11-mercaptoundeconoic acid that enables easy measurement of mass-change sensitivity of PEMC sensors. The finite element model of PEMC sensors predicts resonant frequency values that agree within 2% of experimental values. However, the model gives mass-change sensitivities that are within one order of magnitude of experimentally measured values. Simulations show two interesting properties of PEMC sensors that are observed experimentally. First, the sensor response is log-linear and thus it is most sensitive at low attached mass or low analyte concentration. Second, the sensor becomes less sensitive with increased attached mass or at high analyte concentration which gives the sensor the highly desirable property of wide dynamic range of 6-logs.