Study on Tensile and Compressive Bending Deformation Sensor Based on Surface Acoustic Wave

Abstract

SAW sensors are becoming interesting in the field of strain and stress detection applications. The strain of complex structures can be divided into a combination of local surface tension and compression, hence it is pretty important that study the detection of tension and compression for the analysis of complex structures. Here, we fabricated two SAW sensors based ST-cut quartz (78.65 MHz and 157.1 MHz) through photo-lithography and wet-etching processes and focused on their comparative analysis for the bending displacement and strain testing with the performance of the sensor sensitivity studied. The SAW-IDT10 and SAW-IDT5 sensor showed the maximum bending displacement sensitivity of ∼1.9369 kHz mm−1 and ∼4.3887 kHz mm−1, respectively. Additionally, the SAW-IDT5 sensor exhibited up to 2 times higher sensitivity (1570 kHz/%) than that of SAW-IDT10 sensor (786 kHz/%) under the same bending strain conditions. And the SAW-IDT5 and the SAW-IDT10 have both 0.99 and 1 tensile and compression strain gauge factors. Thus SAW sensors with high operating frequency have a higher frequency shift response in detecting micro-strain. Meanwhile, negative frequency shift response to tension and positive frequency shift response to compression of SAW sensors can be used to classify structural deformation in a complex environment in the future.