Abstract: A porous poly(2-acryl-amido-2-methyl-propane sulphonic acid)-based humidity sensing element is disclosed which provides improved range of humidity measurement and response time with little or no hysteresis. It includes: (a) a non-conductive substrate which has a pair of electrodes formed thereon; (b) a porous poly(2-acryl-amido-2-methyl-propane sulphonic acid) film formed on said electrodes. The porous poly(2-acryl-amido-2-methyl-propane sulphonic acid) film is formed by first forming a non-porous poly(2-acryl-amido-2-methyl-propane sulphonic acid) film on the electrodes, then subjecting the non-porous poly(2-acryl-amido-2-methyl-propane sulphonic acid) film to a heat treatment at temperatures between about 170° C. and 240° C. such that a porous structure is formed in said poly(2-acryl-amido-2-methyl-propane sulphonic acid) film.

Abstract: A method for forming a solid state humidity sensor is disclosed which comprises the steps of: (a) dissolving a tungstate salt into an aqueous solution; (b) adjusting the pH of the aqueous tungstate salt solution to below 8.5; (c) forming one or a pair of electrodes on an insulating substrate; (d) placing the substrate into the pH-adjusted aqueous tungstate salt solution and heating the aqueous solution containing the substrate at temperatures above 70.degree. C. to thereby form a pyrochlore-type crystalline tungsten trioxide film over the electrode or pair of electrodes; and (e) forming another electrode over the pyrochlore-type crystalline tungsten trioxide film if only one electrode is formed during step (c).

Abstract: A method for forming a solid state humidity sensor is disclosed which comprises the steps of: (a) dissolving a tungstate salt into an aqueous solution; (b) adjusting the pH of the aqueous tungstate salt solution to below 8.5; (c) forming one or a pair of electrodes on an insulating substrate; (d) placing the substrate into the pH-adjusted aqueous tungstate salt solution and heating the aqueous solution containing the substrate at temperatures above 70.degree. C. to thereby form a pyrochlore-type crystalline tungsten trioxide film over the electrode or pair of electrodes; and (e) forming another electrode over the pyrochlore-type crystalline tungsten trioxide film if only one electrode is formed during step (c).