GHz SAW strain sensors under high mechanical load conditions

Abstract

Strain sensors have been developed in various fields by converting mechanical deformation into electrical signals. Surface acoustic wave (SAW) devices are beneficial for strain sensing due to their simplicity of fabrication and wireless operation capabilities. In this study, we investigate SAW strain sensors operating at 1.25 GHz . The fabricated SAW resonators using standard photolithography technology are characterized with a custom-made cantilever setup capable of applying defined strain values up to approximately −4000 µϵ to 4000 µϵ. From these measurements, a high responsivity even up to this high strain values is demonstrated. We also explore the impact of geometric design parameters on strain-sensing performance. We vary the length of the SAW resonator and observe that the longer the SAW resonator, the more responsive the device gets to strain changes. When the distance between the two reflectors confining the SAW is 2207 μm , the responsivity to strain is 114.99 Hz μ ϵ⁻¹. In summary, this study investigates the feasibility of GHz SAW resonators as high-strain sensors on non-flexible substrates with a custom-built experimental setup, to evaluate their potential for future applications in extreme mechanical environments.