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Physical chemistry, Analytical chemistry, Composites, Nano-materials
Humidity sensing is of particular concern for many industrial applications. Humidity sensors have typically been based on a reversible interaction between a polymer and water vapour. There is work published on gas sensors based on polymer gold nanoparticle composites, where the conductivity of the composite decreases on interaction with the gas. This happens because the swelling of the polymer which increases the electron hopping distance between the gold nanoparticles. The device in this work is a poly vinyl alcohol silver nanoparticle composite cast on an interdigital electrode array. On application of a dc bias, a current develops which is proportional to levels of humidity from 10% to 60%. The response is reversible and fast at room temperature. Details are provided of the synthesis, characterisation and use of the composite for humidity sensing. In addition the device forms the basis of a sensor for an array of gases.
Power, A.C., Cassidy,J.F. & Betts, A.J. (2009). Development of a Novel Humidity Sensor Based on a Polymer Silver Nanoparticle Composite. ECS transactions, vol. 19,pg. 181-190. doi:10.1149/1.3118551