Highly sensitive capacitive pressure sensors based on elastomer composites with carbon filler hybrids

Flexible pressure sensing applications such as prosthetic limbs and wearable electronics will benefit from pressure sensors with increased capacitive sensitivity. Therefore, to fabricate pressure sensors with increased sensitivity, hybrid composites of a new type of carbon nanofiller, carbon nanostructures (CNS, i.e. branched carbon nanotubes) and graphene nanoplatelets (GNP) at various compositions were mixed with thermoplastic polyurethane (TPU) to tune the composite dielectric properties. Furthermore, in congruence with the global effort towards less wasteful electronic device production, these capacitive sensors were fabricated in a facile and environment-friendly strategy. In a composition of CNS and GNP at a mass ratio of 3:1, the composite sensor shows the highest pressure sensitivity of 2.05 MPa-1 for 0-1.2 MPa pressure, compared with 0.18 MPa-1 for neat TPU, enabling potential wearable pressure sensor applications. The improved performance arises from the combination of interconnected CNS along with the high dielectric constant and suppressed loss of GNP.