Nano-Patterned Ionogel Film for High-Sensitivity and Recyclable Flexible Pressure Sensor

Abstract

Flexible pressure sensors have drawn tremendous attention in the past decades due to their widely advanced applications in electronic skin, intelligent robots and wearable devices. Most existing pressure sensors are developed based on capacitive sensing mechanism, but the sensitivity of such sensors still need to be improved. Herein a high-sensitivity pressure sensor was developed based on the P(VDF-HFP)/[Emim][BF₄] ionogel film. The ionogel film has the characteristics of good mechanical flexibility, good ionic conductivity, high dielectric constant and uniformed nanocone array structure, so the flexible pressure sensor which incorporates it as the dielectric layer shows a high sensitivity (22.38 kPa^−1 within 0–3 kPa, and 15.17 kPa^−1 within 3–15 kPa), fast response (0.29 s) and relaxation (0.16 s) time and good long-term stability. The good solubility of the P(VDF-HFP) copolymer in acetone and the non-crosslinking of the [Emim]^+ and [BF₄]^− within the copolymer network give the ionogel the ability to be recycled, thus endowing the critical component of the pressure sensor with 100% recyclability of structure and function. In addition, the sensor was successfully applied to identify fingertip force and map the pressure distribution of different objects, demonstrating that the pressure sensor can be used as part of wearable devices and human–machine interfaces to sense pressure.