Preparation of gold-poly(vinyl pyrrolidone) core-shell nanocomposites and their humidity-sensing properties

The humidity-sensing properties of gold (Au)-poly(vinyl pyrrolidone) (PVP) core-shell nanocomposites were investigated. Au-PVP nanocomposites were synthesized and then incorporated into a capacitive-type humidity sensor as a dielectric. Because of the adsorption/desorption of water molecules, the variation of capacitance under different humidity levels was examined by the capacitance-frequency conversion circuit and recorded by a LabVIEW system in terms of the frequency shift. As the relative humidity (RH) increased from 11.3 to 93%, the output frequency decreased monotonically, with a sen sitivity of about-136 Hz/% RH. Also, the good reproducibility and stability, fast response, and low hysteresis made the pellet a suitable candidate for humidity sensing.