A Wireless Passive Frequency Selective Surface Strain Sensor With Low Transverse Sensitivity

Due to its wireless and passive operating features, strain sensors based on frequency selective surface (FSS) are garnering more and more attentions. Unfortunately, current FSS strain sensors are sensitive to both longitudinal and transverse strains, which is unfavorable in practical applications. In this work, a miniaturized FSS strain sensor based on a meander line aperture structure is proposed and investigated in terms of the strain dependence of its resonances. The experimental results indicate that the resonance frequency of the FSS sensor reduces from 14.691 to 14.658 GHz when the longitudinal tensile force increases from 0 to 40 N. Similarly, the resonance frequency of the FSS sensor reduces from 14.6374 to 14.6342 GHz when the transverse tensile force increases from 0 to 40 N. The FSS sensor’s sensitivity is 5.96 kHz/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> for longitudinal strain and 0.578 kHz/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> for transverse strain, indicating that the FSS sensor is only sensitive to longitudinal strain and the influence of the transverse strain can be omitted.