Executive Summary : | Chemical gas sensors based on conductometric changes, mainly semiconducting metal oxides (MOs), are gaining attention due to their simplicity, ease of fabrication, and low cost. However, these sensors face issues such as poor selectivity, sensitivity, repeatability, long-term stability, and sensor life. To address these issues, a nanostructure array of MO-thin films (MO-TFs) in controlled dimensions is needed. Top-down methods require high fabrication costs, while bottom-up methods require low-cost fabrication. Developing nanostructures of controlled sizes and morphology with low-cost techniques is essential for low-cost air quality monitoring sensors. The colloidal self-assembly lithography technique, which uses a monolayer of polystyrene/silica particles as a mask, is an emerging method for creating reliable, highly sensitive, and selective gas sensor materials. To detect CO, NO?, NH?, and H?S air pollutants, colloidal-lithography-assisted nanostructures of ZnO, WO?, CuO, and NiO (MO-NS) will be integrated with controlled periodicity on thin films of these materials. Metal nanoparticles (Pt, Pd, Au) will be surface doped on MO-NS/MO-TF architectures to enhance the sensing response. The developed nanostructured thin films will be integrated into MEMS chips to study selectivity performance and develop an appropriate mathematical model for real-time gas concentration prediction. The project aims to explore the colloidal lithography technique to design and develop MO-NS-based sensing layers that meet sensitivity, selectivity, and stability for air pollutants detection, potentially transferring this technology for mass production. |