Full metadata record
| DC Field | Value | Language |
|---|---|---|
| dc.contributor | Department of Mechanical Engineering | en_US |
| dc.contributor.advisor | Su, Zhongqing (ME) | en_US |
| dc.contributor.advisor | Zhou, Limin (ME) | en_US |
| dc.creator | Wang, Qingqing | - |
| dc.identifier.uri | https://theses.lib.polyu.edu.hk/handle/200/14380 | - |
| dc.language | English | en_US |
| dc.publisher | Hong Kong Polytechnic University | en_US |
| dc.rights | All rights reserved | en_US |
| dc.title | Additively manufactured nanocomposite sensors with low-dimensional nanofillers for multiphysics sensing : from structural battery status evaluation to health monitoring of composites | en_US |
| dcterms.abstract | The rapid development of next-generation energy systems, wearable electronics, and lightweight multifunctional composites is driving the need for intriguing sensing technologies that can operate reliably across a broad spectrum of mechanical and acoustic environments. Conventional sensors such as strain gauge, lead zirconate titanate (PZT) wafers, or brittle fibre Bragg grating (FBG), while they are effective in specific regimes, often suffer from limitations such as high rigidity, poor compatibility with host structures, or constraints on frequency bandwidth, being confined to a narrow range. In particular, scalable, flexible, and broadband sensing solutions remain underexplored, despite their critical importance for applications spanning from personalized healthcare to structural health monitoring (SHM). | en_US |
| dcterms.abstract | In this PhD research project, a new class of nanocomposite sensors based on low-dimensional conductive fillers is developed and validated, demonstrating its capability of offering broadband sensing spanning from quasi-static strain gauging, through acoustic vibration measurement, to ultrasonic guided wave acquisition. The performance of the developed sensors is systematically evaluated across multiphysics scenarios: monitoring charge–discharge-induced strain evolution and external impacts in structural batteries, detecting acoustic signals for wearable healthcare applications such as speech recognition, and enabling ultrasonic guided wave–based SHM in fiber-reinforced polymers (FRP) composites. Additive manufacturing-driven fabrication strategy progresses in a stepwise manner, beginning with standalone sensors produced via aerosol jet printing (AJP), advancing to hybrid systems that combine fused deposition modeling (FDM) with AJP to embed sensors within carbon fiber–reinforced polymer (CFRP) laminates, and culminating in totally additively manufactured multifunctional composites with inherent self-sensing capabilities. | en_US |
| dcterms.abstract | To start with, an implantable graphene–polyvinyl alcohol (PVA)-coated glass fiber sensor is first developed and integrated into structural batteries using dip-coating where it achieves ultra-low strain detection limits of 0.009% in tension and stable durability over 2000 cycles. Beyond capturing charge–discharge-induced deformations, the sensor provides rapid detection of external impacts, enabling early warnings against thermal runaway and mechanical damage. This establishes the feasibility of embedding sensitive nanocomposite sensors within structural energy storage systems for real-time monitoring under both electrochemical and mechanical stimuli. | en_US |
| dcterms.abstract | Extending this concept from energy devices to structural composites, a non-intrusive graphene nanoplatelet/epoxy sensor is then co-cured within glass fiber–reinforced polymers (GFRPs) using stencil printing. Benefiting from seamless material compatibility, the embedded sensor combines the inherent strength of GFRPs with broadband sensitivity, detecting responses from quasi-static strains to ultrasonic guided waves up to 600 kHz. This highlights the potential of structurally integrated nanocomposite sensors for in situ SHM, while preserving the host composite’s mechanical integrity. | en_US |
| dcterms.abstract | While these efforts demonstrate feasibility, ensuring reliable and scalable fabrication becomes critical for practical applications. To accommodate this, AJP is employed to precisely formulate and deposit graphene/cellulose nanocrystal (CNC) inks with varied concentrations. Process optimization ensures uniform deposition, and the resulting sensors exhibit tunable sensitivity and stable performance across strain regimes ranging from quasi-static to ultrasonic. This advancement underscores the capability of AJP to deliver reproducible and customizable nanocomposite sensors tailored for diverse monitoring needs. | en_US |
| dcterms.abstract | The broad frequency responsiveness of AJP-printed sensors further enables their application in both wearable healthcare and SHM. A polyurethane-encapsulated graphene/CNC acoustic sensor is developed using AJP, which demonstrates high sensitivity (9.7×10-6 dB⁻¹) and achieves 95.9% accuracy in digit recognition assisted by machine learning, offering an assistive platform for individuals with speech impairments. At higher frequencies, the printed sensor network embedded into glass fiber–reinforced polymer (GFRP) laminates captures impact waves, enabling accurate impact localization and advancing SHM in demanding environments. These embedded demonstrations highlight that AJP-printed sensors can be seamlessly integrated into structural composites, suggesting a natural progression toward manufacturing not only the sensing components but also the structural host itself via additive manufacturing. | en_US |
| dcterms.abstract | Building on this concept, this research advances the framework of “totally-additive-manufacturing” by combining FDM with AJP to fabricate multifunctional CFRP composites. Structural and sensing components are directly printed in a seamless process, producing composites with embedded nanocomposite networks that maintain mechanical integrity while offering ultrahigh sensitivity to strains and ultrasonic perturbations up to 200 kHz. This approach demonstrates a new paradigm for multifunctional structural design, where load-bearing capacity and self-sensing capabilities are integrated by design rather than retrofitted. | en_US |
| dcterms.abstract | In conclusion, this PhD study establishes a comprehensive framework for the design, fabrication, and application of broadband nanocomposite sensors, spanning from standalone devices to fully integrated multifunctional composites, by leveraging advancements in additive manufacturing. By uniting low-dimensional conductive materials with additive manufacturing technologies, this research not only expands the fundamental understanding of scalable sensing architectures but also opens practical pathways for real-time monitoring in energy systems, wearable healthcare, and advanced structural composites. The outcomes highlight the transformative potential of additive manufacturing in creating next-generation multifunctional structures that combine mechanical robustness with intelligent self-sensing capabilities. | en_US |
| dcterms.extent | xxx, 179 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.accessRights | open access | en_US |
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