Quartz crystal microbalance VOCs sensor based on dip coatedpolyaniline emeraldine salt thin films

Abstract

Quartz crystal microbalance (QCM) technique has been used to detect a number of aromatic volatileorganic compounds (VOCs) vapors widely used in research and industrial fields. Detection was basedon dip coated polyaniline emeraldine salts (PANI-ES) thin films doped with three different acids,i.e. hydrochloric acid (HCl), dodecylbenzene sulfonic acid (DBSA) and 1,5-naphtalene disulfonic acids(1,5-NDSA)) on AT-cut 10 MHz QCM electrode. Frequency change was recorded upon adsorption anddesorption of (VOCs) on PANI films. It was found that frequency shifts varied linearly with both vaporconcentration in part per million (ppm) and film thickness in nanometer (nm). Frequency changes areassumed to be mainly due to electrostatic interactions established between vapor molecules and dopantagents within PANI-ES films. Particularly, PANI-DBSA films were found to be highly sensitive (∼7 Hz/ppm),selective to para-xylene (over toluene and benzene) and have a limit of detection of 3 ppm. Interestingly,the films exhibit excellent recovery within less than 3 min