Sprayed piezoresistive flexible composite coating sensor for measuring strain measurement in steel structures

Monitoring the stress and strain in the critical structural details of steel structures is of great significance for ensuring structural safety. This study proposes a sprayed piezoresistive flexible composite coating sensor that is easy to manufacture, industrialize, and standardize. A simple fabrication process is designed. And the experiment proves that the sensor has excellent performance of high linearity, sensitivity, and stability, and a clear piezoresistive response. The coating sensor comprises three layers: an isolation layer, a composite sensing layer, and a protective layer. The piezoresistive matrix parameters of the sensor are estimated through numerical simulations. The piezoresistive response, sensitivity, and stability of the coating sensor are studied experimentally using six sensors. The results indicate that the sensor in that the voltage of the sensor follows a step-change law similar to that of the strain. The theoretical values of σx are in good agreement with the predicted values, and it preliminarily shows the sensor has the potential for practical application. The experimental data from multiple sensors with similar initial resistances matched the simulated values obtained using the estimated piezoresistive matrix well.