Vibration and sensitivity analysis of double-layered non-uniform piezoelectric microcantilever as a self-sensing mass sensor

Abstract

Piezoelectric microcantilevers are specially popular in microelectromechanical system (MEMS) devices due to their high accuracy, environmental friendliness, low response time, and compatibility with compact designs. Since mass sensors are an important application of piezoelectric microcantilevers (PMCs), it is particularly important to determine PMCs sensitivity to nanoparticle absorption. For this purpose, a dynamic analysis was carried out to derive the equation governing vibrations of a PMC in air and water environments. A sphere chain model was used to model hydrodynamic forces acting on the PMC. In order to utilize the bending of the PMC for determining the output current from the piezoelectric layer, the resulting equation was solved by taking into account how the PMC geometrical discontinuities affected eigenvalues. In addition to the sensitivity of natural frequency and amplitude of these sensors, sensitivity of output electric current from their piezoelectric layer is also important. Therefore, the sensitivity of these parameters to nanoparticle absorption was analyzed and compared so as to select the suitable parameter for achieving satisfactory performance of PMC mass sensors in air and liquid working environments. The importance of selecting proper geometrical dimensions in the design of PMC mass sensors is realized by considering the fact that their sensitivity can be enhanced by properly selecting their dimensions. Accordingly, the effects of geometrical dimensions of the sensor on its sensitivity were determined through Sobol sensitivity analysis. The simulation results indicated that the sensitivity of output current from the piezoelectric layer and that of the vibration amplitude in the first three modes were the suitable parameters determining the performance of the PMC mass sensor in air and fluid environments, respectively.