A novel electronic nose based on porous In2O3 microtubes sensor array for the discrimination of VOCs.

We have innovatively developed an electronic nose consisting of only one type of semiconductor metal oxide (SMO) material. The representative SMO material, porous In2O3 microtubes in this work, offered great surface area and large gas penetration channels. By using a solvent casting process, different amounts of porous In2O3 microtubes were coated on Al2O3 substrate, forming a resistometric SMO sensor array-based electronic nose. Each sensing unit in the electronic nose exhibited independent response toward ethanol. We have successfully applied this electronic nose to distinguish four alcohols at the same concentrations (100 ppm), and also utilized the electronic nose for the discrimination of 14 volatile organic compounds (VOCs). Clear differentiation among all the 14 VOCs both at their immediately dangerous to life or health (IDLH) and the permissible exposure limit (PEL) concentrations has been achieved with no errors or misclassifications. We expect that this method will expand the application of SMO sensor array-based electronic nose which has been largely limited by the selection of commercially available SMOs and dopants.