Phase-Separation-Induced PVDF/Graphene Coating on Fabrics toward Flexible Piezoelectric Sensors

Clothing-integrated piezoelectric sensors possess great potential for future wearable electronics. In this paper, we reported a phase-separation approach to fabricate flexible piezoelectric sensors based on poly(vinylidene fluoride) (PVDF)/graphene composite coating on commercially available fabrics (PVDF/graphene@F). The structural units of -CH₂- and -CF₂- of PVDF chains were arranged directionally due to the structural induction of graphene and water during phase separation, which is the key for electroactive phase enrichment. In optimized case, integrating into fabric substrates endows the phase-out PVDF/graphene composite coating 4 times higher voltage output than its film counterpart. Piezoelectric sensor based on PVDF/graphene@F exhibits a sensitivity of 34 V N^-1, which is higher than many reports. It also shows low detecting threshold (0.6 mN), which can be applied to distinguish the voices or monitor the motion of body. This simple and effective approach toward PVDF/graphene@F with excellent flexibility provides a promising route toward the development of wearable piezoelectric sensors.