A capacitive humidity sensor based on gold-PVA core-shell nanocomposites

This paper describes an application of polymer encapsulated gold nanoparticles used as relative humidity (RH) sensors. The gold nanoparticles are prepared by a most popular method, and the polymer, polyvinyl alcohol (PVA), is used to encapsulate Au for getting core-shell hybrid structures. Scanning electron microscopy (SEM) and atom force microscopy (AFM) were used to observe the structural and morphological properties of the polymer encapsulated gold nanoparticles. X-ray diffraction (XRD) was used to estimate the crystallite size of gold nanoparticles. And then gold (Au) and gold-polyvinyl alcohol (Au-PVA) nanoparticles were applied to construct Au sensors and Au-PVA sensors, respectively. Sensing experiments were examined by measuring the capacitance shift of Au and Au-PVA sensors which have been put into different relative humidity environments. The results showed that the Au-PVA sensors had higher humidity sensitivity, better stability, faster humidity response and better reproducibility than the Au sensors. Therefore, a capacitive humidity sensor based on Au-PVA core-shell nanocomposites is potentially developed.