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 immobilization 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 concentration with high sensitivity (17.85 kHz/ppm, a fast response time (60 s), and recovery time (85 s).