Electrical conductivity response of methanol sensor based on conductive polyindole

Abstract A methanol sensor based on polyindole was investigated and reported in this work. The polyindole sensor response was monitored by the electrical conductivity change at room temperature. The sensor responses of various vapors from non-polar, low polar, and high polar solvents were investigated; the highest relative responses of conductivity were observed when exposed to vapors from high polar solvents, especially methanol possessing the highest dielectric constant (e) and hydrogen bonding interaction (δ H ) relative to other vapors inducing the highest interaction to the conductive polymer. The discrimination analysis of sensor was evaluated by the principal component analysis (PCA), it demonstrated that the sensor possessed the good discrimination efficiency towards high polar vapors. The sensor response depended on the doping mole ratio which was related to electrical conductivity of the conductive polymer. In this work, the dPIn/FeCl 3 with the doping mole ratio of 10:1 provided the highest methanol relative response of conductivity of 57.83 at the low concentration of 11.36 ppm using nitrogen as a base gas. The sensitivity to methanol vapor was 5.27 ppm −1 with the correlation coefficient (R 2 ) of 0.9965, the theoretical limit of detection was as low as 0.048 ppm. The sensor based on the dPIn/FeCl 3 10:1 is shown here a good candidate for use as a methanol sensing material.