Improvement of humidity sensing properties of PVDF-TiO2 nanocomposite films using acetone etching

Abstract

In this work, we enhanced the humidity sensing properties of the polyvinylidene fluoride titanium dioxide (PVDF-TiO2) nanocomposites based capacitive humidity sensors by modifying the film surface. The surface morphology of the PVDF-TiO2 nanocomposite films was modified using the acetone etching. The structural, morphological, thermal and hydrophilic properties of the nanocomposite films were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC) and contact angle measurements. To prepare the nanocomposite films, 2.5 wt% solution of PVDF and 0.5 wt% solution of TiO2 was mixed in the volumetric ratio (1:2). To fabricate the humidity sensors, the PVDF-TiO2 nanocomposite films were deposited on interdigitated ITO electrodes by spin coating technique. The humidity sensing properties of the sensors were investigated in the relative humidity (RH) range of 30–80%. The sensor shows a linear and stable response over the whole investigated range. The response and recovery times of the composite based sensors are to be 45 s and 11 s, respectively. The average value obtained for the hystersis is 1.05%.