Functional Nanomaterials for Sensing Devices

Advances in functional nanomaterials have led to new strategies for creating highly sensitive and scalable sensing technologies. This dissertation explores four nanomaterial-based platforms aimed at detecting volatile organic compounds (VOCs), foodborne pathogens using lateral flow assays (LFA), and bacterial identification through two kinds of MXene-based materials for surface-enhanced Raman spectroscopy (SERS). Each platform was designed to improve sensitivity, selectivity, and practical application. Chapter Two introduces a roll-to-roll (R2R) manufactured chemiresistive sensor based on a MoS₂ single-walled carbon nanotube (SCNT) composite. The use of electro-sprayed electrodes provided uniform resistance and enhanced gas adsorption, while tetrafluorohydroquinone (TFQ) functionalization increased acetone selectivity, which provided a pathway for scalable VOC detection. Chapter Three applies a dual-colorimetric method to an aptamer-based lateral flow platform for Salmonella typhimurium detection, where polystyrene microparticles decorated with gold nanoparticles (AuNPs) and aptamers provided improved sensitivity and signal quantification. Chapter Four focuses on Ti₃C₂-Au nanocomposites as tunable SERS probes for identifying Listeriamonocytogenes, with optimization of 4-mercaptobenzoic acid (4MBA) and antibody conjugation. Chapter Five presents a Mo₂TiC₂T_x-AuNPs hybrid material, achieving a 10¹ CFU/mL detection limit for L. monocytogenes in buffer, while requiring significantly less gold than Ti₃C₂T_x-based probes. Although some signal reduction was noted in complex matrices, both Ti₃C₂T_x and Mo₂TiC₂T_x platforms demonstrated strong SERS activity and reliability. Further work will focus on improving signal stability and reducing background noise. In summary, this research contributes to the development of scalable and highly sensitive nanomaterial-based sensors and addresses key challenges in environmental monitoring and foodborne pathogen detection to improve food safety.