Properties of a polyethyleneimine-based sensor for measuring medium and high relative humidity

Abstract

In this paper a method of preparing polyethyleneimine films, which improves the water resistance of polymer humidity sensors, is proposed. The polyethyleneimine was cross-linked at elevated temperature using 1,4-butanediol diglycidyl ether, both being dissolved in dimethylsulfoxide. The optimum composition of polymer and optimum reaction temperature were obtained. Resistive-type sensors have been prepared by dip coating. The sensor preserves excellent durability in high humidities or even after immersion in water. The electrical properties of the sensors were investigated by impedance spectroscopy.