A Portable Sensing Device Based on MoO ₃ /Nb ₂ CT _<i>x</i> for Detection of Acetone in the Exhaled Human Breath

Exhaled breath is a noninvasive way to diagnose diseases and provides important biochemical and physiological information about the health of an individual. Acetone originating from exhaled breath is increasingly recognized as a valuable biomarker with substantial potential for the diagnosis and monitoring of diabetics. This work demonstrated the sensitive and highly selective acetone characteristics of chemiresistive sensing devices based on MoO3, Nb2CTx, and MoO3/Nb2CTx materials. Here, we developed a smart paper-based MoO3/Nb2CTx sensor for acetone detection at low ppm. The MoO3/Nb2CTx sensor exhibits remarkable sensitivity, showing a high sensor response of 10.24 at 1 ppm, which further rises to 180.30 at 100 ppm acetone concentration. Notably, it possesses a lower limit of detection (LOD) of 0.55 ppm in the acetone concentration range of 1–100 ppm, which is useful for diagnosing diabetic patients through exhaled breath monitoring. Density functional theory (DFT) studies were further carried out for a better understanding of the acetone sensing mechanism. The species examined through DFT analysis include MoO3, MoO3-acetone, MoO3/Nb2CTx, and MoO3/Nb2CTx-acetone. This research introduces a low-cost, portable electronic device for detecting acetone, which may be used to identify the presence of acetone in the environment as well as in the exhalation of human breath.