High-Sensitivity Microwave Acetone Gas Sensor With SnO₂–MXene Nanocomposites

This article presents a novel high-sensitivity microwave sensor for low-concentration acetone gas detection. The electrically coupled resonator loaded with an interdigital capacitor (ECR-IDC) structure is the sensing area, with a maximum electric field strength of $3.71 \times 10^{{5}}$ V/m. The SnO2–MXene nanocomposites with different MXene doping ratios were prepared using an ultrasound-assisted dispersion method, which significantly changed the conductivity of the gas-sensitive material. Experimental results revealed that the developed sensor exhibited a high sensitivity of 51.7 mdB/ppm and excellent linearity in the detection range of 1–20 ppm, attributed to the heterojunction-like structure of the SnO2–MXene nanocomposites. The introduction of MXene induced a decrease in conductivity, which is beneficial for microwave sensing, and simultaneously increased the active sites of the composite for acetone binding, finally improving the sensitivity of the microwave sensors. The demonstrated high performance of the developed sensor validates its potential in breath analysis, toward future applications in designing novel healthcare devices.