Wearable ion gel based pressure sensor with high sensitivity and ultra-wide sensing range for human motion detection

Abstract

Wearable and flexible pressure sensors are applicable to a variety of fields, including human motion detection. Covering the entire range of human motion, they should be able to detect a wide range of pressures, from low to high, with high sensitivity. The ion gel-based pressure sensors, a deformable and stretchable material, measure the capacitance caused by an electric double layer at the electrode - electrolyte interface, and the capacitance significantly increases as the contact area increases. In this work, a series of ionic liquid complexes (ILC) consisting of solvated ionic liquid and conventional ionic liquid were prepared and explored in terms of ionization state. Additionally, the effects of the ILCs have also been confirmed when incorporated into a thermoplastic polyurethane matrix as ion gels. Using the prepared ion gels, wearable pressure sensors were fabricated by sandwiching the ion gel between two cotton fabrics. A conductive knit tape served as an electrode to maximize the contact area between the electrode and ion gel, resulting in high sensitivity and an ultra-wide range of sensing. This study opens up the potential application of wearable ion gel-based pressure sensors with novel ionic liquid complexes.