Ultra-sensitive gas sensor for dimethyl methylphosphonate with tin oixde nanopattern structure control

Abstract

Sarin gas is the most notorious gas for its toxicity among the Chemical Warfare Agents (CWA) because it causes respiratory paralysis within a few minutes after exposure and can be made easily. Therefore, it is important to detect the sarin gas especially at extremely low concentration. However, it is too lethal to use it in lab-scale, so we used Dimethyl methylphosphonate(DMMP) instead which has the same detection mechanism due to a structural similarity with sarin gas. In this paper, the high-resolution Al-doped $SnO_2$ nanopattern with high aspect ratio (~13) was fabricated by Secondary Sputtering Lithography. This unique top-down lithographic technique also enabled ultra-small grains of $SnO_2$ channel materials and highly scattered Al dopants. The DMMP gas sensor with this Al-doped $SnO_2$ nanopattern showed an outstanding sensitivity in range from 50 ppb to 2 ppm ($R_a/R_g$ = 43.3 at 50 ppb) and good selectivity due to its ideally controlled structure.