Development of nanopatterned multi-array electronic-nose (E-Nose) by top-down lithography

Abstract

Electric nose (E-nose), an artificial sense system that mimics the human olfactory system using a multi-array sensor system, is key technology of high-performance gas detection. However, since design and fabrication of multi-array sensing channel have been significantly limited with time-consuming and non-universal process, development of commercializable and high-throughput top-down fabrication approaches is critically required. Here, for the first time, commercializable high-resolution top-down lithography is developed for E-nose fabrication. Five different metal oxide semiconductor (MOS) nanopattern channels ($NiO, CuO, Cr_{2}O_{3}, SnO_{2}, WO_{3}$) were fabricated into multi-array sensors by unique lithographic approach, that utilize the sputtering of the metals’ grains by low-energy bombardment of the plasma. The nanopattern channels shows i) high-resolution (15 nm scale), ii) high-aspect-ratio (11

width: 14 nm height: 150 nm) and iii) ultra-small grains (5.1 nm) with high uniformity in cm2 scale, leading to high sensitivity for each target analytes. Our E-nose system composed of five MOS nanopattern channels could successfully distinguish seven different hazard analytes including volatile organic compounds (VOCs

$C_{7}H_{8}, C_{2}H_{5}OH, CH_{3}COCH_{3}, C_{6}H_{14}, C_{3}H_{6}O$) and nitrogen containing compounds ($NO$ and $NH_3$) were successfully distinguished. It is expected that this unique top-down lithography can provide a simple and reliable approach for channel diversification and high-resolution channel fabrication in commercial level and e-nose would have further applications in real life situation.