First-principles study of diabetes-associated VOCs detection from breath using nitride nanotubes

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia, and its increasing global prevalence highlights the need for accessible, rapid, and non-invasive monitoring techniques. Breath analysis has gained considerable attention as a promising diagnostic approach because exhaled volatile organic compounds (VOCs), particularly acetone and ethanol, have been associated with metabolic changes and blood glucose variation. In this study, density functional theory (DFT) calculations were performed to investigate the adsorption behavior of acetone and ethanol on aluminum nitride nanotubes (AlNNT), gallium nitride nanotubes (GaNNT), and aluminum-gallium nitride nanotubes (AlGaNNT). The calculated adsorption energies ranged from -2.751 to -5.256 eV, indicating thermodynamically favorable and spontaneous interactions between the VOC molecules and nanotube surfaces. AlGaNNT exhibited the strongest affinity toward ethanol, with an adsorption energy of -5.256 eV, the largest Mulliken charge redistribution, and the most exothermic enthalpy change, suggesting its potential for ethanol sensing. In contrast, GaNNT showed the strongest adsorption toward acetone, with an adsorption energy of -3.383 eV and noticeable electronic perturbation near the frontier orbital region. AlNNT demonstrated balanced but comparatively less selective adsorption behavior toward both VOCs. Although the high recovery times at room temperature indicate limitations in spontaneous sensor regeneration, temperature-assisted desorption may improve practical reusability. Overall, these findings provide a theoretical basis for designing nitride-nanotube-based breath sensors for non-invasive diabetes monitoring.