Unusual Selective Monitoring of <i>N,N</i> -Dimethylformamide in a Two-Dimensional Material Field-Effect Transistor
Akito Fukui, Keigo Matsuyama, Hiroaki Onoe, Shun Itai, Hidekazu Ikeno, Shunsuke Hiraoka, Kousei Hiura, Yuh Hijikata, Jenny Pirillo, Takahiro Nagata, Kuniharu Takei, Takeshi Yoshimura, Norifumi Fujimura, Daisuke Kiriya
Abstract
N, N -Dimethylformamide (DMF) is an essential solvent in industries and pharmaceutics. Its market size range was estimated to be 2 billion U.S. dollars in 2022. Monitoring DMF in solution environments in real time is significant because of its toxicity. However, DMF is not a redox-active molecule; therefore, selective monitoring of DMF in solutions, especially in polar aqueous solutions, in real time is extremely difficult. In this paper, we propose a selective DMF sensor using a molybdenum disulfide (MoS 2 ) field-effect transistor (FET). The sensor responds to DMF molecules but not to similar molecules of formamide, N, N -diethylformamide, and N, N -dimethylacetamide. The plausible atomic mechanism is the oxygen substitution sites on MoS 2, on which the DMF molecule shows an exceptional orientation. The thin structure of MoS 2 –FET can be incorporated into a microfluidic chamber, which leads to DMF monitoring in real time by exchanging solutions subsequently. The designed device shows DMF monitoring in NaCl ionic solutions from 1 to 200 μL/mL. This work proposes the concept of selectively monitoring redox-inactive molecules based on the nonideal atomic affinity site on the surface of two-dimensional semiconductors.