Tilted Micro-Force Sensing Using a Dual-Port Surface Acoustic Wave Resonator Sensor

Abstract

Tilted micro-force sensing is of significant value for wafer contact testing, microindentation characterization, and precision machining. To investigate the response of surface acoustic wave (SAW) sensors under inclined loading conditions, this paper presents a miniaturized SAW micro-force sensor based on a dual-port resonator architecture. The sensor employs ST-X cut quartz as the piezoelectric substrate, and the dual-port resonator is formed by interdigital transducers and reflectors to convert strain variations induced by inclined loading into a frequency-shift response. A relationship between the applied inclined micro-force and the resonant frequency shift is established through finite-element simulations and subsequently validated experimentally. Experimental results show that, near an operating frequency of approximately 79 MHz, the sensor exhibits good linearity with respect to the applied force at inclination angles of 30°, 45°, and 60°. The experimentally characterized sensitivities are 91.14 kHz/N, 127.69 kHz/N, and 151.63 kHz/N, respectively. These results indicate that the proposed dual-port SAW sensor can provide a stable force-frequency response under inclined loading conditions, offering a feasible sensing approach for inclined micro-force detection. [2025-0251]