Screen-Printed 1-m-Long Sensors for Damage Detection in Welded Engineering Structures

In this study, we demonstrate 1-m-long sensors for damage detection in welded civil engineering structures. The sensors were fabricated using screen printing and were based on a hybrid construction of a conductive intermittent pattern (made of silver) with embedded sensing elements made of carbon-based resistive ink. The sensing elements were oriented in one direction corresponding to the expected maximum strain direction. Because the electrical resistance of the silver interconnects (1.88 $\pm ~0.14~\Omega $ ) was much lower than the resistance of sensing elements (2.04 ± 0.17 $\text{k}\Omega $ ), the sensing properties of the sensors depend mainly on the properties of the carbon ink (gauge factor (GF) of 13.46). Thanks to such construction, the sensing direction of the sensor could be specified at the desired orientation, and the power consumption of the 1-m-long sensor could be reduced to about $15~\mu \text{W}$ . Low power consumption is especially important regarding the applications in sensing systems that are based on Internet of Things (IoT) devices. The sensors were evaluated during various laboratory tests. It was demonstrated that although the sensor is 1-m-long, it can detect even small damage (a few mm long) effectively and hence can be suitable for applications to monitor welded construction elements in real civil structures.