대변형율 측정을 위한 탄소나노튜브 유연 스트레인센서 특성 연구

Abstract

In this study, a carbon nanotube based flexible strain sensor was experimentally studied to develop a large deformable sensor. The sensor was made of silicone rubber and a multi-wall carbon nanotube(MWCNT) as an electrically conductive filler with less than 3wt% content. Since th naanocomposite sensor has piezoresistivity, its electrical resistivity is changed according to deformation. The sensor was fabricated as a sandwich structure to prevent buckling under large deformation and the electrodes were made with conductive fabrics to be able to connect it on large deformable materials. For feasibility test of rubber parts, the fabricated strain sensor was attached on rubber specimens and its maximum strain and adhesion performance were tested with a tensile strength tester. The maximum strain rate was about 50% and much higher strain performance can be expected with better adhesive condition. The voltage output of the flexible strain sensor is 3.2mV, which is very stability. From the sensing characteristic experiments, the flexible strain sensor had lower sensitivity (~0.27) than commercial foil strain sensors. The flexible sensor had inherently hysteresis under loading conditions due to the viscoelastic properties of the resin, such as ductility stress relaxation. And also, the flexible strain sensor required a sufficient recovery time ti obtain a stable signal because the viscoelastic properties are time dependent. Flexible strain sensors are less sensitive than commercial strain sensor, but can have sufficient sensing characteristics to be large strain sensors. The output voltage range of the sensor can be enough to cover the large deformation of the sensing object completely due to it lower sensitivity. Further research should develop a high hysteresis compensation algorithm due to viscoelasticity to pbtain more accurate rubber parts deformation measure.