Senskin deformable silicone-elastomer sensors for structural health monitoring: assessment of strain sensitivity and correction for thermal expansion

Abstract

Within the framework of SENSKIN EU project (grant No. 635844), we have developed a soft capacitive sensor using silicone dielectric elastomer for Structural health monitoring (SHM). This sensor has a thin layer of stretchable silicone dielectric film and soft silicone electrodes as the active layer, which transduces strain signal into the easy-monitored capacitance change. The sensor output is measured as a ration of the sensor’s capacitance to the known value of the reference capacitor. The capacitive output of the sensor showed a linear response upon stretching in the strain range of 4.5 % to 5.5% with a pre-strain of 5.0 %. The sensor output increased by 0.01 when the strain was increased by 1.0 %. The sensor was exposed to a temperature change from -35 oC to 55 oC (the supposed working temperature range) with a ramping of 0.2 oC/min and, as a result, it showed a linear temperature dependence behavior with a slope of -0.001 sensor output per oC. Therefore, with the help of the embedded Platinum-1000 temperature sensor, the thermal expansion effect on the capacitive output can be excluded from the actual strain-induced capacitance change. These results provide practical reference to the application of the silicon-elastomer sensor for the SHM systems.