An Ionic Liquid Based Strain Sensor for Large Displacements

Abstract

A novel ionic liquid based strain sensor is fabricated for high strain measurements (up to 10% and higher). A tubular silicone microchannel with a diameter of 310 μm and a length of 5 mm is filled with an ionic liquid (1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide). The final sensor has an outer diameter of 650 μm and a length of 15 mm. When the channel is axially loaded, geometrical deformations change the electrical properties of the liquid channel. 4-point impedance spectroscopy with the integrated circuit AD5933 from Analog Devices and a dedicated galvanostatic front-end is performed to characterize this piezoresistive effect. The highest sensitivity is observed in the frequency range from 10 to 25 kHz, with corresponding gauge factors between 2 and 2.5 for an elongation of 10%.