Experimental and Theoretical Analysis of Molecular Sensors for Ultra-Sensitive Aldehyde (vocs) Detection Mimicking Human Breath

The detection of low concentration formaldehyde as a potential breath marker for lung cancer is a technical challenge in the current gas sensor field due to its weak electrical signal and its susceptibility to humidity. Here, we report on a combination of density functional theory (DFT) and experimental data to establish that aldehydes in super-saturated water vapor (80% humidity) can be detected using nanotubes molecular field-effect transistors. A thin film of high-purity semiconducting single-wall carbon nanotubes (SWCNTs) network and a catalytic metal were used as the sensing material. The fabricated back-gated Pt-decorated SWCNT FET sensors showed a response of 26.99% to 300 ppm formaldehyde at room temperature and humidity of 80% which is 11.58 times greater than that obtained for its detection using back gated bare SWCNT FET. DFT calculation also confirmed that the sensitivity of Pt-decorated SWCNT toward methanediol (formaldehyde in humidity) detection is 7.29 greater than that obtained for methanediol detection using pristine SWCNT. Moreover, the fabricated back-gated Pt-decorated SWCNT FET sensors exhibited a good recovery of 115 sec towards 300 ppm formaldehyde at 70 °C with sub-ppb theoretical calculation limit-of-detection (LOD). Hence, back-gated Pt-decorated SWCNT FET sensor is a promising candidate for easy screening of lung cancer patients.