Theoretical modeling and experimental testing for SAW torque sensing

In some special occasions, the conventional methods of torque measurement can´t meet the requirements. SAW torque sensors have the characteristics of passive and wireless, which can adapt to the rotating and moving measurement objects preferably. In this paper, it firstly establishes a SAW torque sensing model which is based on the Lagrangian coordinates and describes strain-induced resonant frequency fields by employing the theory of nonlinear elasticity. Then the piezoelectric substrate cut orientation and the acoustic wave propagation direction is optimized according to the torque sensitivity and the electromechanical coupling coefficient. Finally SAW resonators are fabricated on ST-36° cut type quartz, the experimental platform of the SAW torque sensing is set up and the experimental results are analyzed.