Stretchable and compressible piezoresistive sensors from auxetic foam and silver nanowire

Abstract Silver nanowire (AgNW) based flexible, stretchable and compressible piezoresistive sensors were prepared using porous substrates having negative Poisson ratio (auxetic foams). The morphology and piezoresistive properties of the auxetic foam sensors (AFS) were characterized and compared with that of sensor using a conventional foam substrate (CFS). The AFS showed improved piezoresistive sensitivity compared to the CFS under both tension and compression modes, with improvement up to 290% and 165% (in terms of gauge factor), respectively. The AFS had good stability in air and water, showing repeatable and reliable sensing performance under cyclic loading and unloading situations in both. We further show the potential application and the advantages of the auxetic foam sensors through a series of sensing demonstrations. Such porous piezoresistive sensors with improved sensitivity could find potential application as sportswear, safety gears, filtration and flow detection medium, smart healthcare foams, prosthetic liners and so on.