A highly water-resistive humidity sensor based on silicon-containing polyelectrolytes prepared by one-pot method

3-Aminopropyltriethoxysilane (APTS) was quaternized with n-butyl bromide (BB) followed by hydrolysis via a simple one-pot method to obtain an electrolyte with crosslinkable silicol groups. This sample was dip-coated on interdigitated gold electrodes and formed a crosslinking structure by heat treatment to prepare a thin film resistive humidity sensor. It was found that the sensor showed an impedance change from ∼107 to 103 Ω in the humidity range of 11–97% RH, exhibiting a high sensitivity and moderate linearity on a semi-logarithmic scale. In addition, the impedance of the sensor changed little even after being soaked in water for 2 h, indicating a high water-resistance and good stability. This is proposed to result from the formation of a crosslinking structure and better adhesion with the electrode substrate. The sensor exhibited a highly reversible response characterized by a very small hysteresis of ∼1% RH. The response time and the effect of concentration of dip-coating solution on the humidity sensitive characteristics were investigated.