Emerging trends in microfluidic-assisted nanomaterial synthesis for their high-resolution gas sensing applications

Conventional methods of detecting hazardous gases and aerated microorganisms were judged unfeasible for use in a point of use environment. The use of a lightweight prototype and an easy fabrication provides significant advantages over conventional gas sensing systems. It would be ideal if scientists could develop relatively small, sensitive gas sensors that could detect trace amounts of biomarker gases and airborne pollutants. In the realm of sensors, microfluidics technology enables the analysis of a small quantity of samples by facilitating the use of a minimum amount of sensor materials. Moreover, the capacity to scrutinise a diminutive sample volume result in a sensor that exhibits prompt responsiveness. However, attaining selectivity towards the target analyte has been a major challenge. With this objective of obtaining specificity in gas sensing, this comprehensive study highlights recent breakthroughs in microfluidic device design and synthesis of sensing materials for selective gas and aerated pollutants. The present review focuses on brief explanation of a microfluidic device design, the substrate material, channel size, shape, deposition, and cleaning methods for synthesis of selective gas sensing materials based on noble metals, semiconductor oxide nanoparticles, and their composites. Further, the gas sensing application of these materials is also discussed in detail. This article is the first to provide an extensive overview of the substrate materials, design fabrication, deposition, and cleaning techniques, microfluidic synthesis of sensing materials for selective gas sensing, and the various detection approaches required for novel and efficient gas sensing analysis using recent microfluidic technology.