Development of a laser micro-machined interdigitated capacitive strain sensor for structural health monitoring applications

Monitoring of structural health plays a crucial role in condition-based maintenance and prediction of unsafe or damaged infrastructures. We have developed an interdigitated capacitive (IDC) strain sensor integrated in a wireless monitoring system that could be used for structural health monitoring (SHM). The 125-μm thin brass IDC sensors were fabricated by laser micromachining followed by an encapsulation in a deformable polymer. The wireless monitoring system was implemented using a commercial wireless module Texas Instruments eZ430-RF2500 for use with multiple sensors simultaneously. A graphical user interface (GUI) was developed to store data and perform real-time analysis remotely. The wireless communication distance was up to 35 m inside buildings. The sensors were characterized and the entire system was demonstrated with both single and dual sensors. Our system is also capable of multi-modality sensing for continuous and real-time monitoring.