Dependence of the Lamb wave viscosity sensor on the liquid morphology

Lamb wave sensors performing well in liquid medium are good choices for monitoring viscosity. Despite the advances in the biosensing and chemical application of Lamb wave viscosity sensors, the analysis of the dependence of the sensors on liquid morphology is still needed. Therefore, a Lamb wave viscosity sensor has been fabricated. A novel two-dimensional (2-D) array model for viscosity sensing is put forward based on the finite element analysis (FEA) method. The dependence of the resonant frequency of the sensor on liquid morphology has been simulated and experimentally tested. By comparing simulations and experiments, the frequency responses are dependent on the liquid loading position, thickness and coverage ratio on the Lamb wave sensor. In addition, the frequency response of the sensor to viscosity has been conducted using glycerol-water mixtures on the basis of controlled liquid morphology, showing a linear relationship with the square of viscosity, with 238.92 ppm/(mPa s)0.5 in simulation and 153.16 ppm/(mPa s)0.5 in the experiment. Our work potentially allows for reducing the random error of the experiments and for more exploration of Lamb wave viscosity sensors in the future study.