Superhydrophilic polymer modified galvanic array moisture sensor chip with stable/improved lifetime towards enhanced dew condensation detection

Abstract

A stable, sensitive, and accurate moisture chip with long life time is always desired in practical applications. Therefore, it is very important to investigate several factors that affect these properties. In this context, an enhancement in the sensitivity and life time of galvanic array moisture chip used for dew condensation detection has been reported. The chip is capable of early prediction of dew condensation promptly and precisely. The sensing aptitude of the chip with the smallest electrode gap ~500 nm is very fast and can detect water molecules, even much before actual dew condensation occurs. Furthermore, through modification of the surface of the chip using modified superhydrophilic polymer coating, the output could be enhanced by ~2 orders than that of moisture chip without coating. The wettability was promoted by the coating and hence adsorption of water on the surface between the electrodes, generating galvanic current. It could increase the number and area of bridging water droplets between the electrodes, leading to an enhanced output. Interestingly, with the modified superhydrophilic polymer coating used in this study, a wide thin film of water was observed covering the whole surface of moisture chip, not easily observed otherwise. Optical images, contact angle measurement and output current results supported the fact that a moisture chip showed long term stability and excellent capacity towards detection of dew condensation. The life time of moisture chip with superhydrophilic surface is also comparatively long (time period for this study ~20 months).