Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Applied Biology and Chemical Technology | en_US |
| dc.contributor.advisor | Zheng, Zijian (ABCT) | en_US |
| dc.creator | Shi, Yuqing | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14543 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Nanostructured sensors and integrated systems for advanced biosensing | en_US |
| dcterms.abstract | In the critical domains of public health surveillance and personalized medical interventions, the capability of high-performance sensors to achieve real-time monitoring and precise intervention has become a fundamental requirement. However, current technologies face three major challenges: insufficient sensitivity in complex matrices, limited long-term operational stability, and a lack of intelligent responsiveness. To overcome these barriers, this dissertation advances sensing design and integrated system engineering centered on the core theme of enhancing sensing performance through nanomaterials. A structured three-tiered research framework is established, beginning with ultrasensitive detection of trace analytes in complex environments, advancing to stable wearable monitoring under dynamic conditions, and culminating in intelligent closed loop intervention system for pathological regulation. | en_US |
| dcterms.abstract | To achieve an ultralow detection limit in electrochemical biosensing, a printable electrochemical biosensor was developed with an ultralow detection limit and high operational stability. The sensor features a dendritic gold nanostructure modified with a PBASE-functionalized interface, tailored for efficient antigen recognition. By leveraging the increased surface area and localized electric field amplification afforded by the fractal electrode morphology, the sensor enables ultralow detection limit of SARS-CoV-2 and H₃N₂ antigens in wastewater, reaching a detection limit of 0.025 fg/mL. Without requiring complex sample preprocessing, the device exhibits excellent selectivity and operational robustness, thereby enabling real-time viral surveillance in wastewater-based epidemiology (WBE). | en_US |
| dcterms.abstract | Beyond achieving ultralow detection limits, long-term stability and washability are essential for real-world deployment. To address the need for stable and continuous monitoring of sweat biomarkers, a wearable textile-based sodium ion sensor was developed by incorporating β-Bi₂O₃ nanoflakes with fast ion diffusion. These nanostructures substantially enhance the adhesion strength and structural stability of the ion-selective membrane, resulting in excellent washability and mechanical durability. | en_US |
| dcterms.abstract | The sensor maintained over 90% of its initial performance after 20 washing cycles. Integrated with a Bluetooth Low Energy module, the system enables real-time visualization of sodium levels in sweat, offering a practical and reliable platform for personal health monitoring under dynamic conditions. These results establish a durable sensing front end suitable for integration into a closed loop therapeutic architecture. | en_US |
| dcterms.abstract | Building on this sensing front end, we realize a comprehensive closed-loop system coupling continuous monitoring with precise intervention. The architecture integrates a high-performance flexible pH sensor and a PMA hydrogel battery array that ensures reliable power below 0°C. To achieve autonomous regulations, an active therapeutic unit was developed by combining a nanostructured palladium black electrode with a pH-sensitive PAM/CS hydrogel. In a cold liver model, sensor-detected acidosis triggers chitosan protonation, leading to rapid hydrogel swelling and NAC release while the palladium interface manages proton flux. This synergistic cycle demonstrates a practical platform that coordinates detection, decision, and delivery to effectively mitigate oxidative stress and enhance organ viability. | en_US |
| dcterms.abstract | This dissertation systematically explores how nanomaterials enhance sensing performance at the device and system levels. First, dendritic gold nanostructures are employed to amplify sensitivity through localized surface effects. Then, β-Bi₂O₃ nanoflakes are introduced to improve the structural stability and washability of wearable sensors. Finally, functional hydrogels are integrated to enable a closed-loop therapeutic response, completing a full-chain intelligent sensing-intervention system. The three types of sensing systems developed in this work demonstrate substantial application potential in early public health warning through wastewater surveillance, personalized health management via sweat biomarkers, and clinical resource optimization by improving organ viability. Collectively, these strategies not only address fundamental bottlenecks in current sensing technologies but also offer a scalable paradigm that advances the frontiers of intelligent, adaptive sensing systems. | en_US |
| dcterms.extent | x, 220 pages : color illustrations | en_US |
| dcterms.isPartOf | PolyU Electronic Theses | en_US |
| dcterms.issued | 2026 | en_US |
| dcterms.educationalLevel | Ph.D. | en_US |
| dcterms.educationalLevel | All Doctorate | en_US |
| dcterms.LCSH | Electrochemical sensors | en_US |
| dcterms.LCSH | Biosensors | en_US |
| dcterms.LCSH | Nanostructured materials | en_US |
| dcterms.LCSH | Wearable technology | en_US |
| dcterms.LCSH | Hong Kong Polytechnic University -- Dissertations | en_US |
| dcterms.accessRights | open access | en_US |
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