"Functional Nanomaterials for Sensing Devices" 

Ya-Ching Yu, MSE PhD Candidate 

Advisor: Prof. Lia Stanciu

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ABSTRACT

The advancement of functional nanomaterials has enabled the development of highly sensitive and scalable sensing technologies. This dissertation focuses on three nanomaterial-based platforms for detecting volatile organic compounds (VOCs), foodborne pathogens via lateral flow assays (LFA), and bacterial identification using surface-enhanced Raman spectroscopy (SERS), all designed to enhance sensitivity, selectivity, and practical applicability. The first research chapter presents a roll-to-roll (R2R) manufactured chemiresistive sensor for acetone detection, utilizing a MoS2-single-walled carbon nanotube (SCNT) nanocomposite. Electro-sprayed electrodes provided uniform resistance and high gas adsorption, while tetrafluorohydroquinone (TFQ) functionalization improved acetone selectivity, demonstrating a scalable approach for VOC detection. The second chapter applies a dual-modality colorimetric analysis method to an aptamer-based lateral flow (ABLF) platform for Salmonella typhimurium (S. typhimurium) detection. Polystyrene microparticles decorated with gold nanoparticles (AuNPs) and functionalized with aptamers demonstrated enhanced sensitivity and selectivity. Dual color quantification methodologies further improved detection accuracy, bridging LFA technology from lab to market. The third chapter develops Ti3C2-Au nanocomposites as Raman probes for detecting Listeria monocytogenes (L. monocytogenes). Various Ti3C2-Au ratios exhibit tunable SERS effects, while functionalization with 4-mercaptobenzoic acid (4MBA) and antibody was systematically optimized to maximize SERS signal intensity, ensuring high sensitivity and selectivity. The system demonstrated excellent SERS performance and adjustability, providing rapid and reliable pathogen detection. In summary, this research contributes to the development of scalable and highly sensitive nanomaterial-based sensors, addressing key challenges in environmental monitoring and foodborne pathogen detection to improve food safety.