Piezoresistive strain sensing behavior of flexible conductive microporous membrane using acidic ionic liquid

Flexible piezoresistive strain sensors are smart materials used for sensing applications. In the present work, a flexible piezoresistive strain sensor was developed by infiltrating acidic ionic liquid (IL) [BMIM HSO4] in poly (vinylidene fluoride) (PVDF) polymer using a solvent casting technique. The use of IL leads to the generation of pores of uniform shape at lower concentrations (~10 wt%), thus enhancing mechanical flexibility by allowing more space to stretch. Furthermore, the pores contained IL inside, providing extra ions for charge conduction, thus improving the sensitivity of the material. Maximum flexibility and gauge factor of 5.29 were obtained for ratio 5 to 10 wt% of IL. Maximum elasticity was obtained for ratio IL/PVDF (5:95) in comparison to pure PVDF. An increase in dielectric constant and conductivity was observed for samples containing IL. The most important part of IL can be reused and shows biocompatible behavior. The developed system showed a more flexible, durable, and repeatable performance for strain sensing applications for human and structural health monitoring.