A Y type SAW mass sensor with metal array reflectors

摘要

A new Y type dual path surface acoustic wave (SAW) mass sensor with apodized interdigital transducer (IDT) and metal array reflectors is reported. In order to suppress the spurious signal reflected from the chip edges and improve the sensitivity of the sensor, a metal array reflector is designed between the output IDT and the chip edge to change the original SAW propagation direction. The temperature effect on the measurement path is compensated by a reference path. The simulation result of the acoustic energy distribution of the reflectors has been reported. The characteristics of the sensor have been tested by the delay-line active oscillation circuit. The results show that passband ripple suppression is improved by more than 1 dB by reflectors. Also, a very low relative temperature coefficient of the sensor is obtained (only about 6.2 Hz/℃). The Q value of the sensor is up to 1.1 x 10~4 in oscillator mode. Mass loading effect sensitivity is about 5.24 GHz cm~2/g with a good linearity.