Tetsuya Miyagishi

Stability and reliability of capacitive-type relative humidity sensors using crosslinked polyimide films

Abstract Newly developed crosslinked polyimide and fluorinated polyimide-based humidity sensors were fabricated for office building and factory applications. Both sensors showed good initial sensor performance. The stability and the reliability of these sensors were evaluated by exposing the sensor elements to various test conditions. The crosslinked polyimide sensor was resistant to chemicals and the crosslinked fluorinated polyimide one exhibited long-term stability in harsh environments. By using these sensors properly, their sensor performance is superior to that of most commercially available capacitive-type sensors.

A thin-film polysulfone-based capacitive-type relative-humidity sensor

Abstract A capacitive type relative humidity sensor utilizing newly developed cross-linked fluorinated polyimide has been fabricated using thin film technology and evaluated for commercial building and factory applications. The sensor showed a good initial performance with less than 1% r.h. hysteresis and a 0 ± 0.1% r.h./°C temperature coefficient of capacitance along with good stability especially under high temperature and high humidity conditions. Also, because of the inherent chemical resistance of the polyimide, good sensor stability when subjected to volatile environments has been demonstrated.