High reliable gas sensor based on crystal-facet regulated α-Fe₂O₃ nanocrystals for rapid detection of exhaled acetone

The exploitation of the highly reliable gas-sensing device for exhaled acetone detection possesses momentous and capacious development prospects in the field of an early noninvasive diabetes diagnosis. Considering that the characteristics of crystal facets will impact the gas-sensitive performance, herein three different resistive gas sensors were successfully developed by utilizing the stable α-Fe₂O₃ with different crystal facets as the sensitive materials. The gas-sensitive performance testing results reveal that the (110) crystal faceted α-Fe₂O₃ sensor exhibits relatively superior comprehensive gas sensitivity toward acetone. Particularly, it is worth mentioning that the sensor demonstrates reliable sensitivity, rapid response (25 s)/recovery (3 s) speed, and strong anti-interference capability in detecting 2 × 10⁻⁶ acetone for the concentration threshold of diabetes, even when exposed to prolonged periods in variable environments. Furthermore, by simply validating the feasibility of the exhalation diagnosis using the as-prepared gas sensor, the (110) faceted α-Fe₂O₃ gas sensor can effectively discriminate the states of healthy human exhalation and the simulated diabetic exhalation. Through integrating the experimental and theoretical analyses, the superior acetone-sensitive performance of the (110) faceted α-Fe₂O₃ gas sensor can principally be interpreted in correlation with crystal facet-dependent gas adsorption capacity and defect-forming ability. These results not only imply a tremendous application perspective in monitoring acetone gas at sub-ppm concentration, but also open up an effective throughway to develop reliable gas-sensing devices for early non-invasive diabetes screening.