A Novel Molecularly Imprinted Polymer-Based Carbon Nanotube-Coated Microwave Sensor for Selective Detection of Methanol Gas

In this letter, a novel molecularly imprinted polymer (MIP)-based carbon nanotube (CNT)-coated microwave sensor is developed for the selective sensing of methanol gas. First, a 2.45 GHz broadband monopole antenna with a 400 MHz 10-dB bandwidth is designed. A 5-mm Interdigitated Electrode (IDE) structure is then added to the antenna for high-precision sensing. The IDEs are coated with highly sensitive and conductive CNT with a MIP layer that is selective and specific for methanol gas. Measured sensor results confirm 5.3–58.6 parts-per-thousand (ppt) methanol detection with a sensitivity of approximately 1.0 MHz per 5 ppt. The developed sensor showed high selectivity for methanol when tested against acetone. The repeatability of the sensor was ensured by conducting several experiments on different days over a span of 15 days, all with the same concentration and ambient conditions. Furthermore, the antenna is not tuned out of its transmission bandwidth during gas sensing, indicating potential for integration into sensor nodes.