Water Status on Micro/Nano Gap Between Galvanic Arrays and Flowing Current Around 100% in Relative Humidity

Dissimilar metal arrays with micron/nano gap detect water droplet and agglomerated molecules between them by galvanic action. At 100% in relative humidity (RH), dew condensation occurs on solid surface. The purpose of this study was to clarify the detection behaviour of the above-mentioned galvanic arrays around 100%RH and simultaneous measurement of galvanic current and observation of arrays and gap surface were carried out. Research results showed that the response current depended on RH owing to equilibrium of water molecules between vapor and adsorbed state on the sensor surface when RH increases up to 100%. At 100%RH, current showed steady value determined by balance between condensation of liquid water and evaporation of vapor. Once liquid water was formed on the sensor surface over 100%RH, the response current depended on the size of water determined kinetically. This dependence was observed during the decreasing process of the relative humidity over 100% and even under 100%.