Size effects on a one-dimensional defective phononic crystal sensor

The influence of size effects on one-dimensional defective phononic crystal (PnC) sensors based on simplified strain gradient elasticity theory (SSGET) is studied in this paper. PnCs have been widely used in high-sensitivity gas and liquid sensors by introducing defects to disrupt the perfect PnC modes. In comparison with classical elasticity theory, the SSGET includes two microstructure-related material parameters that can accurately reflect the size effects of the structure. In this paper, the stiffness matrix method was used to calculate the transmission coefficients of the proposed model, avoiding the numerical instability of the transfer matrix method. The results show that the size effects at the microscale affect the perfect PnC bandgap’s frequency range, and the microstructure constants impress the resonant frequency while detecting liquids. Consequently, the accuracy of the sensor is reduced. These findings provide a theoretical basis for designing microscale PnC sensors.