Environmentally Friendlier Printable Conductive and Piezoresistive Sensing Materials Compatible with Conformable Electronics

Flexible and conformable conductive composites have been developed using different polymers, including water-based polyvinylpyrrolidone (PVP), chemical-resistant polyvinylidene fluoride (PVDF), and elastomeric styrene-ethylene-butylene-styrene (SEBS) reinforced with nitrogen-doped reduced graphene oxide with suitable viscosity in composites for printable solutions with functional properties. Manufactured by screen-printing using low-toxicity solvents, leading to more environmentally friendly conductive materials, the materials present an enormous step toward functional devices. The materials were enhanced in terms of filler/binder ratio, achieving screen-printed films with a sheet resistance lower than Rsq < 100 Ω/sq. The materials are biocompatible and support bending deformations up to 10 mm with piezoresistive performance for the different polymers up to 100 bending cycles. The piezoresistive performance of the SEBS binder is greater than double that the other composites, with a gauge factor near 4. Thermoforming was applied to all materials, with the PVP-based ones showing the lowest electrical resistance after the bending process. These conductive materials open a path for developing sustainable and functional devices for printable and conformable electronics.