Sensitivity-Enhanced detection of acetone gas using MXene-Immobilized planar microwave sensor

This work presents the noncontact immobilization of Ti3C2Tx MXene on a planar microwave resonator sensor via a polyimide film to enhance the gas detection sensitivity, enabling the characterization of the part per million -level of acetone gas. Sandwiching a polyimide (PI) film confined an intense electromagnetic field between the resonator's interdigital capacitor structure and the MXene layer, maintaining a significant interaction between the acetone gas molecules and the resonator's EM field via the MXene layer. Therefore, contactless immobili-zation of the MXene layer enhanced the acetone gas detection sensitivity by 110% compared to the resonator gas sensor with MXene deposited directly on the resonator surface. As a proof of concept, two sensor prototypes were implemented using resonators with layers of PI film and MXene and resonators with MXene only and were applied to detect a wide range of acetone gas concentrations. Immobilizing the layers of PI film and MXene on the microwave resonator achieved a linear correlation between the resonant frequency and acetone gas concen-tration with high sensitivity (17.85 kHz/ppm, a fast response time (60 s), and recovery time (85 s).