A flexible capacitive sensor based on the electrospun PVDF nanofiber membrane with carbon nanotubes

Abstract

Flexible pressure sensors have been increasingly recognized over the past several decades, but there is still a challenge to fabricate them with a superb sensitivity and large sensing range. In this paper, a flexible capacitive pressure sensor based on the electrospun polyvinylidene fluoride (PVDF) nanofiber membrane with carbon nanotubes (CNTs) was developed to measure the pressure. The electrospinning CNT-PVDF nanofiber membrane can overcomes the limitations of the traditional solution-dip-coating for adhering conductive materials to the porous surface. The microstructure and characterization of the CNT-PVDF nanofiber membrane were analyzed by SEM, AFM and FTIR. By increasing the permittivity and decreasing the Young's modulus of the CNT-PVDF dielectric layer, the capacitive sensor exhibits high sensitivity (∼0.99/kPa), fast response (∼29 ms) and excellent cyclic loading/unloading stability (＞1000 cycles). Moreover, experiments were also conducted to investigate influence of the thickness and bending radius of the sensor as well as temperature and humidity of the environment. In addition, a 3 × 3 sensor network attached on the hand was used to measure the spatial distribution and magnitude of tactile pressure. The proposed sensor has great potential for application in soft robotics and electronic skin.