Nitrogen-Doped\nCarbon Quantum Dots Activated Dandelion-Like\nHierarchical WO<sub>3</sub> for Highly Sensitive and Selective MEMS\nSensors in Diabetes Detection

High sensitivity, low concentration, and excellent selectivity\nare pronounced primary challenges for semiconductor gas sensors to\nmonitor acetone from exhaled breath. In this study, nitrogen-doped\ncarbon quantum dots (N-CQDs) with high reactivity were used to activate\ndandelion-like hierarchical tungsten oxide (WO<sub>3</sub>) microspheres\nto construct an efficient and stable acetone gas sensor. Benefiting\nfrom the synergistic effect of both the abundant active sites provided\nby the unique dandelion-like hierarchical structure and the high reaction\npotential generated by the sensitization of the N-CQDs, the resulting\n16 wt % N-CQDs/WO<sub>3</sub> sensor shows an ultrahigh response value\n(<i>R</i><sub>a</sub>/<i>R</i><sub>g</sub> = 74@1\nppm acetone), low detection limit (0.05 ppm), outstanding selectivity,\nand reliable stability to acetone at the optimum working temperature\nof 210 °C. Noteworthy that the N-CQDs facilitate the carrier\nmigration and intensify the reaction between acetone and WO<sub>3</sub> during the sensing process. Considering the above advantages, N-CQDs\nas a sensitizer to achieve excellent gas-sensitive properties of WO<sub>3</sub> are a promising new strategy for achieving accurate acetone\ndetection in real time and facilitating the development of portable\nhuman-exhaled gas sensors.