P1K-3 Contactless Torque and Temperature Sensor Based on SAW Resonators

A wireless passive SAW sensor based on three one-port resonators and capable of simultaneous torque and temperature measurement is presented. The sensing element is made on Y+34deg cut quartz substrate and the resonant frequencies are in the range from 433 to 437 MHz. Interrogation of the sensor is performed through an RF rotary coupler by short RF pulses. A microprocessor in the interrogation unit analyses the spectrum of SAW responses and calculates a temperature compensated torque value. Experimental results show that the temperature measurement error is within plusmn1deg at any angle of the shaft and the torque measurement error does not exceed plusmn1% of full scale within the range from -40deg to +125degC