In-situ formation of an ion-doped porous structure for high sensitive humidity sensing utilizing low-cost UV sensitive glue

This paper presents a novel method for in-situ formation of an ion-doped porous structure for high sensitive humidity sensing utilizing low-cost UV sensitive epoxy. Nano-size granular polymer structures can be directly deposited on a substrate by exposing a UV sensitive epoxy in an organic solvent of alcohol. SEM observations indicate that the deposited porous structure is constructed by stacking polymer nano-particles of around 300 nm in size. A deliquescence salt of MgCl₂ is simultaneously introduced into the porous sensing layer for enhancing the vapor absorption ability during the polymerization process. Results show that the sensitivity of the humidity sensor with the ion-doped porous structure is enhanced over 365 times greater than the sensor fabricated with the same material without ion-doped porous structure. The proposed method provides a simple and fast way to fabricated high performance humidity sensors.