Experimental characterization of an ionically conductive fluid based high flexibility strain sensor

Abstract

In this study, a high flexibility strain sensor based on ionic liquid, which is a mixture of aqueous sodium chloride and glycerin pump in silicone tube, is developed. Gold-coated electrodes are inserted into both ends of the tube to make good contact with the liquid. When the silicone tube is affected by an external force, its geometry and electrical characteristics of the mixture inside the tube are changed, resulting in the change in the sensor resistance. The proposed sensor was fabricated and experimentally characterized. The 4-point resistance measurement based on alternating Howland current source was applied to the sensor for measuring the change in resistance of the sensor. A circuit board with PIC16F877A microcontroller is also developed for data acquisition and result display. Experimental results show that the sensor is highly flexible, i.e., can suffer from a stretch up to 50% with stable gauge factor in the range of 2.1 to 2.47. With its simplexes and high-flexibility, the proposed sensor has high potential to be applied to wearable and portable applications.