Fabrication and characterization of piezoresistive flexible pressure sensors based on poly(vinylidene fluoride)/thermoplastic polyurethane filled with carbon black‐polypyrrole

Abstract Electrically conductive composites of thermoplastic polyurethane (TPU), poly(vinylidene fluoride) (PVDF), and carbon black‐polypyrrole (CB‐PPy) were prepared by melt compounding followed by compression molding or by filament production followed by fused filament fabrication (FFF). The storage modulus ( G ′) and complex viscosity ( η *) of the composites increased with the addition of CB‐PPy leading to a more rigid material. The electrical and rheological percolation threshold of composites were 5 and 3 wt%, respectively. In fact, composites with 5 wt% or more CB‐PPy content display G ′ higher than G ″ indicating a solid‐like behavior. Furthermore, the addition of CB‐PPy increased the electrical conductivity of all composites. However, the electrical conductivity values of composites containing 5 and 6 wt% of CB‐PPy produced by compression molding are one and seven order of magnitude higher than those of FFF composites with same composition. Compression molded and 3D printed composites with 6 wt% of CB‐PPy displayed high sensitivity/gauge factor, large measurement range and reproducible piezoresistive response during 100 loading‐unloading cycles for both processing methods. The results presented in this study demonstrated the potential use of FFF for producing piezoresistive flexible sensors based on PVDF/TPU/CB‐PPy composites.