Increasing temperature sensing resolution using multiple non-continuous cascade connected SAWRs

Abstract

This paper proposes a novel approach of multiple non-continuous cascade-connected one-port Surface Acoustic Wave Resonators (SAWRs) at operating frequency of 433.42 MHz to improve the resolution of temperature sensing. Three different sets of SAWR-based temperature sensors have been experimented using one, two, and three cascade connected commercial SAWR(s) to evaluate performance, including sensitivity and sensing resolution, of the temperature sensor with respect to increasing the number of SAWRs in cascade connection. The frequency shifts of all three different configurations were measured at the same time w.r.t. the change in the temperature. The sensitivity is calculated as the ratio of the total frequency shift to the total temperature change. Results demonstrated that not only the sensitivity of the sensor but also the resolution of the sensor to sense the temperature is increased with increasing the number of SAWRs in the cascade connection. Maximum sensitivity on average of 681.81 Hz/°C was noted with 3 SAWRs which is 33.3% higher than the sensitivity of 1 SAWR which was on average 454.54 Hz/°C. Additionally, 1 SAWR could detect on average 9.46 °C of change in the temperature while 3 SAWRs could detected 6.74 °C of change in the temperature, proving the higher resolution of temperature sensing with a greater number of SAWRs. This unique approach of increasing resolution and sensitivity of the sensor can help to develop sensor array using SAWRs which can be operated using single device.