A Capacitive Humidity Sensor Based on an Electrospun PVDF/Graphene Membrane

Abstract

Humidity sensors have been widely used in areas such as agriculture, environmental conservation, medicine, instrumentation and climatology. Hydrophobicity is one of the important factors in capacitive humidity sensors: recent research has shown that the inclusion of graphene (G) in polyvinylidene fluoride (PVDF) improves its hydrophobicity. In this context, a methodology to fabricate electrospun membranes of PVDF blended with G was developed in order to improve the PVDF properties allowing the use of PVDF/G membrane as a capacitive humidity sensor. Micrographs of membranes were obtained by scanning electron microscopy to analyze the morphology of the fabricated samples. Subsequently, the capacitive response of the membrane, which showed an almost linear and directly proportional response to humidity, was tested. Results showed that the response time of PVDF/G membrane was faster than that of a commercial DHT11 sensor. In summary, PVDF/G membranes exhibit interesting properties as humidity sensors.

A Review of Piezoelectric PVDF Film by Electrospinning and Its Applications

“…Hernández-Rivera et al introduced a capacitive humidity sensor fabricated using the PVDF membrane [ 142 ]. The change of dielectric constant of porous nanofilm in the presence of water vapor was the underlying working principle.…”

Recent Advances in Graphene-Based Humidity Sensors

“…Interestingly, such a humidity sensor was integrated with a triboelectric nanogenerator to form a self-powered humidity sensor [179]. Hernández-Rivera et al reported a capacitive humidity sensor based on an electrospun PVDF/graphene membrane, the sensing principle of which was based on the dielectric constant change of membranes due to the water vapor inside fibrous structure, and the enhanced response of the device may be caused by the improved hydrophobicity brought by the incorporation of graphene into the PVDF [180]. Lin et al prepared a graphene/PPy composite by a chemical oxidative polymerization method with graphene, which acted as the sensing materials in the impedance humidity sensor.…”

Using Annealing Treatment on Fabrication Ionic Liquid-Based PVDF Films

“…PVDF as a smart material has been widely used for miscellaneous application fields, such as sensor and actuator, energy harvesting, and medical devices due to the merits of flexibility, light weight, high sensitivity, excellent response over a wide frequency, and so on [1][2][3][4][5][6][7][8]. Compared to PZT ceramics, PVDF does not have the negative defects of brittleness, large stiffness, weight, and thermal conductivity, etc.…”