Design and characterization of a passive wireless strain sensor

A novel passive wireless-interrogation strain sensor is presented in this paper. The sensor employs a planar inductor with a series connected interdigital capacitor to eliminate the wire connection for power supply and data transmission. The sensor is activated by electromagnetic waves and the resonant frequency of the sensor is interrogated remotely with a single loop antenna by applying an oscillating signal to the antenna and monitoring the frequency response of the voltage across it. The prototype sensor and reader were designed and fabricated. The results of calibration on a constant-strain cantilever beam show great linearity and sensitivity. The innovative wireless strain sensing technology described herein has demonstrated a great potential to extend its applications in structural health monitoring, damage detection, condition-based maintenance, failure prevention and non-destructive evaluation.