3D sprayed polyurethane functionalized graphene / carbon nanotubes hybrid architectures to enhance the piezo-resistive response of quantum resistive pressure sensors

Quantum Resistive pressure Sensors (pQRS) can be integrated into flexible electronics, smart textiles, robotics etc. Our last research on hybrid nanocomposites by 3D spraying, highlights the positive input of graphene combined with carbon nanotubes to build a robust hierarchical conducting architecture. Our best formulation of pQRS transducers, thermoplastic polyurethane (TPU) functionalized pG2%/CNT4% hybrid, exhibited a linear response from 0 to 4 MPa, the highest range ever obtained with a sensitivity as high as 11.29 x 10(-5) kPa(-1). Graphene allowed to multiply by three the piezo-resistive response to compression (Ar) of TPU-CNT up to 60% and improved significantly sensors' stability. More strikingly, hybrid pQRS can convert the classical double peak of the signal resulting from the POISSON's effect at high compression, into a single peak. This performance is an exciting result ascribed to the hybridization of carbon nanotubes (CNT) with pristine graphene (pG) into an architecture keeping contact whatever the direction of solicitation. Hybrid pQRS had also a more stable piezo-resistive behavior whatever the speed of compression, and the mechanical history. Finally, the proof of concept of pressure monitoring and mapping, with a flexible and integrable array of four hybrid pQRS has demonstrated a promising potential for real time sensing. (C) 2020 Elsevier Ltd. All rights reserved.