Impedance Response of Insulator Nanoparticle Films with Condensed Chemical Vapor: Structural Isomers and Aprotic Chemicals

Abstract

Rapid electrical analysis of chemical liquids is a promising technique for on-site evaluation. In this study, the electrical impedance response of insulator nanoparticle films with condensed chemical vapors was investigated in structural isomers and polar aprotic chemical liquids. Headspace vapor was condensed in the nanoscale void between the nanoparticles, and ionic conduction subsequently occurred under an AC voltage. The transient electrical impedance response depends on the vapor pressure and conductivity of the liquid isomers. A chemical liquid of the structural isomers was identified by monitoring the impedance during exposure to its headspace vapor. The response time of the film impedance was 10.6, 4.7, 7.5, and 2.4 s for 1-butanol, 2-butanol, 2-methyl-1-propanol, and tert-butyl alcohol, respectively.  Furthermore, the current conduction mechanism in the polar aprotic chemicals was discussed. Although these chemicals did not form molecular networks with the hydrogen bonds, the electrical current flowed in the system. We proposed that hydrogen bonds mediated by water molecules were formed and proton hopping through the condensed polar aprotic liquid occurred. This proposed method has the potential to detect protic and aprotic polar chemical vapors.