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.