Passive RFID sensor systems for crack detection & characterization

A significant requirement of low-cost sensor systems for defect detection and characterization is to bridge the gap of nondestructive testing & evaluation (NDT & E) and structural health monitoring (SHM). This paper introduces an ultra-high frequency (UHF) passive RFID sensor system for crack detection and potential structural monitoring. The working principles and major research challenges are presented for the new concept of NDT & E sensor systems. One novel approach using 3D antenna and kernel principal component analysis (PCA) is investigated and validated in conjunction with two case studies for evaluation of open and closed cracks. This proposed method can partly alleviate the nonlinearity from wireless channel and demonstrate the feasibility of the in-situ motoring through amplitude and phase of tag's backscattered signals.