Iodine-doped polyphenylacetylene thin film as a humidity sensor

Thinfilms of iodine-dopedpolyphenylacetylene (PPA) have been investigated and used as humiditysensors. Measurements of resistance variations of a PPA/I2 system, induced by relative humidity variations ranging from 10 to 90%, have been performed at constant temperatures (25 and 30 °C). The behaviour of the resistance versus relative humidity is found to be approximately exponential. Our samples show a good reversibility during humidity cycles and a relatively fast response time (a few seconds).