Fabrication and characterization of carbon black-filled PVB and PVDF composites near percolation threshold for pressure sensing applications

Abstract In this paper we compare different piezoresistive composites for pressure sensing applications embedded into the organic coating of metallic substrates such as sheet steel. The composites differ in the used matrix materials, i.e., poly(vinylidene fluoride) (PVDF) and polyvinyl butyral (PVB) as well as in the used filler material. In both cases, carbon black (CB) particles in the nano- to micro-meter range are used as conductive filler. The particles are mixed into the solved matrix material and the resulting composite material is printed by means of the doctor’s blade method on top of also additively printed, interdigitated thick-film silver (Ag) electrodes. After heating, in order to evaporate the solvent and to cure the PV(B, DF) CB layer, the electric resistance of the thick film percolation sensors in dependence of the applied pressure is characterized. The feasibility of the so obtained films for pressure sensing fully embedded into the surface coating of sheet steel substrates is evaluated yielding thresholds in the order of ~1.25 kPa.