Monitoring Metal Surface Crack based on Chipless RFID Sensor

In this study, we propose a chipless RFID sensor for metal surface crack detection and identification based on the frequency domain. The sensor is configured with an innovative patch shape, where the sensor tag comprises four small L-shaped patch antennas forming a cross-like patch antenna, and a substrate constructed from flexible polyimide film laminated together. Modeling and simulation were executed using HFSS at an operating frequency range of 8-12 GHz to ascertain the generation and direction of cracks by assessing changes in resonance amplitude and frequency in the absence of cracks. Analysis of the simulation outcomes reveals that the sensor generates robust RCS signals for 0° crack, 45° crack, and 90° crack. The resonance exhibits distinct and noticeable alterations in amplitude and frequency shift compared to the resonance in the absence of cracks, registering amplitudes of -29dB, -31dB, and -37.5dB, respectively. This capability effectively facilitates the detection of crack generation and direction. Ultimately, the detection and identification of metal cracks are successfully realized.