A wireless passive strain sensor

This paper introduces a wireless passive sensor concept for measurement of one- and two-dimensional strain and bending. An identification opportunity can easily be added to the sensor element to distinguish between different sensor “tags”. The concept is based on the modulation of the frequency domain backscatter signature of a radar target by the measured value. The target itself is realized as a small resonant metamaterial structure which generates an amplitude peak in the radar cross-section at resonance. The modulation is done by a variation of the capacitive element of the resonator by the measured quantity. Benefits of the presented design are the passive chipless buildup allowing a construction for the operation in harsh (e. g. high temperature) environments, the simple standard, low-cost fabrication process, the small footprint, the identification opportunity, the possibility of a FMCW-radar-based readout and the versatility of possible sensor designs.