High-speed multi-parameter sensing system based on wireless passive SAW tags

Abstract

Wireless passive surface acoustic wave (WP-SAW) tags are widely used for onsite real-time monitoring of mechanical moving parts. However, the high running speed of some core parts results in fast variation of the sensing parameters such as stress or strain, which requires high sampling rate. This is challenging for WP-SAW because of its traditional frequency interrogation scheme by frequency sweeping, especially under high temperature. This paper proposed a high-speed sensing system based on WP-SAW tags for the real-time interrogation of multiple parameters including temperature, pressure and strain. The high-speed reading is achieved by interrogation with linear frequency modulated continuous waves, which can achieve a fast single cycle sampling time of 36.25 μs. The sensor tag is built by direct integration of a SAW resonator with a PCB spiral antenna. Langasite is chosen as the SAW substrate to achieve high working temperature. The temperature, pressure and strain sensing ranges of the wired SAW resonators are room temperature to 1000 °C, 0.1 MPa to 0.8 MPa and 0 μϵ to 1000 μϵ, respectively. The design of this wireless passive sensing system demonstrates a feasible monitoring solution that can be widely used in high-speed and high-temperature moving mechanical parts.