(Invited) Metal Oxide Nanowire Array to Overcome Odor Sensing Limits

Abstract

Toward developing advanced cyber-physical system (CPS), interest for a molecular recognition electronics is rapidly increasing for collecting chemical information in our daily life. Among various sensor technology, artificial olfactory sensor targeting on chemical data collection of odor is growing research field due to its promise in wide applications for non-invasive medical diagnosis, environmental monitoring, factory automation, security, smart agriculture, etc. In such applications, a lack of molecular sensing system having both material robustness and capability of molecular discrimination in complex mixtures has been a critical issue for the long-term collection of chemical information. Inorganic nanowires, especially for metal oxide nanowires, are a class of promising materials to overcome such issues due to their excellent material robustness in air and huge surface-to-volume ratio beneficial for effectively capturing and concentrating volatile molecules on their surface. Although a highly sensitive electrical detection of volatile molecules has been demonstrated using semiconducting nanowires up to date, poor understanding and design capability of molecule-to-surface interactions on nanowire surface have substantially limited their performance in artificial olfactory sensor systems which require molecular discrimination in complex mixtures. In this presentation, we demonstrate that designing a coordination structure of ionic species at nanowire surface is of critical importance to control the adsorption, reaction and desorption properties of volatile molecules. The enhanced sensing performance and the molecular selective adsorption property of nanowire were successfully achieved as the results of designed surface coordination structure. In addition, molecular filter/molecular transport controller using nanowire array integrated with sensor device is conceptualized as novel artificial olfactory sensor system to discriminate molecules in complex mixture beyond the previous sensing limits. References: ACS Sens. 7 , 534 (2022) / Chem. Commun. 58 , 6377 (2022) / Chem. Lett. 51 , 424 (2022) / ACS Sens. 7 , 151 (2022) / Chem. Sci. 12 , 5073 (2021) / ACS Appl. Nano Mater. 3 , 10252 (2020) / Commun. Mater. 1 , 58 (2020) / Nano Lett. 20 , 599 (2020) / Nano Lett. 19 , 2443 (2019)