A Highly Selective MEMS-Based Gas Sensor With Gelatin-Carbon Black Composite Film Fabricated by the Thin-Film-Needle-Coating Method

In this article, a novel thin-film-needle-coating (TFNC) method is proposed to fabricate a high-sensitivity and strong identification humidity sensor based on the newly developed carbon black-gelatin composite (CB-GE) film. This study aims to fabricate a highly sensitive, stable, and accurate multitask gas sensor for gas detection. The gas sensor comprises the super-thin CB-GE film and patterned sophisticated electrodes. The microelectromechanical system (MEMS) fabricating method and the TFNC coating method promise the successful fabrication of electrodes and sensitive CB-GE composite film. This CB-GE sensor is tested and verified to have special characteristics like high sensitivity, stable repeatability, and rapid recovery toward the changes in different humidity rates and different concentrations of ethanol and acetone gas. Herein, the CB-GE composite film sensor exhibits a fast response time (7 s) on exposure to water vapor ranging from 10.9% to 83.2% rate humidity. Moreover, it also exhibits a quick response time (20 s) on exposure to ethanol from 39.861 to 441.135 ppm and has good repeatability on exposure to acetone. Depending on specific signal features, the CB-GE sensor demonstrates superior gas selectivity among water vapor, ethanol, and acetone. In the future, this low-cost TFNC-coating method can fabricate CB-GE film sensors via a sophisticated MEMS technique leading to deep potentials in the field of electronic nose.