Humidity sensor using chemically synthesized poly(1,5-diaminonaphthalene) doped with carbon

The chemically synthesized poly(1,5-diaminonaphthalene) (DAN) doped with carbon was applied to a humidity sensor. The poly mer was characterized using Fourier transform infrared, ultraviolet-visible spectrometry, and cyclic voltammetry. The composite polymer film was prepared by mixing the poly(1,5-DAN) powder with acetylene carbon black in various ratios and 6.0 wt% polyvinylidene fluoride in N-methylpyrrolidone. The composite polymer sensor was examined and applied to the amperometric and the resistance-type humidity sensor employing chronoamperometry and impedance spectrometry. The relative humidity was controlled using the standard saturated salt solutions at 20 +/- 0.1 degrees C. Under optimized experimental conditions, the calibration plot for the 15:1 composition sensor showed a straight line over the entire measured range of percent relative hunliditp (RH) without hysteresis. The overall sensitivity was calculated as S = [R(93% RH) - R(12% RH)]/R(93% RH). The current drift was less than +/- 1% for the lower humidity. (C) 2000 The Electrochemical Society. S0013-4651(99)04-058-6. All rights reserved.