Mechanical Engineering
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Item type: Item , Access status: Open Access , Investigation and Characterization of Carbon Films Sputtered on Silica Aerogel Monoliths(2026-07-24) Atash Dehghan, Niknaz; O'Brien, Paul G.This study investigates the deposition of a 500 nm carbon (C) layer onto hydrophilic bare silica aerogels (BSA) using the magnetron sputtering method. By leveraging the mesoporous structure of silica aerogel, a carbon-coated aerogel nanocomposite was produced. Spectroscopic characterization of the resulting nano composite revealed ultraviolet scattering behavior, enhanced visible light absorption, and changes in optical transmittance. FTIR spectroscopy further demonstrated that the carbon layer reduced transmittance in the near-infrared (NIR) and mid-infrared (MIR) regions. Infrared thermal imaging confirmed a photothermal response, where samples coated with a 500 nm carbon layer reached temperatures up to 59 °C under simulated solar irradiation at an intensity of 100 mW/cm². Solara absorptance calculations further showed an increase from approximately 6.9% for BSA to 75.8% for CSSA, indicating enhanced solar energy absorption after carbon sputtering. In addition, carbon capture experiments were performed to evaluate the influence of carbon sputtering on CO₂ adsorption and desorption behavior. The findings demonstrate that carbon sputtering modified the optical and photothermal properties of silica aerogels and provided insight into their potential use in carbon capture applications.Item type: Item , Access status: Open Access , Discovering Correlations Between Genetic Modifications and Structural Changes in Adult Zebrafish Eye Using Optical Coherence Tomography(2026-07-24) Sabour Rouh Aghdam, Shiva; Tabatabaei, NimaVisual impairments, such as refractive errors and cataracts, present a growing global health challenge, driving the critical need for advanced diagnostic imaging and genetically tractable animal models. The zebrafish (Danio rerio) has emerged as a premier model for vision research; however, translating clinical Optical Coherence Tomography (OCT) to adult zebrafish presents significant optical challenges regarding tissue penetration and lateral resolution. This thesis presents an interdisciplinary approach bridging mechanical engineering and vision biology, aiming to optimize a customized OCT imaging framework to uncover the structural consequences of targeted genetic modifications in the adult zebrafish eye. To overcome inherent optical limitations, a dual Spectral-Domain OCT (SD-OCT) platform was engineered and optimized. A custom 1310 nm system was tailored to maximize tissue penetration depth, enabling comprehensive whole-eye biometry from the anterior cornea to the posterior retina. Concurrently, an 880 nm system equipped with a specialized probe was optimized for high-resolution microstructural retinal imaging. Paired with rigorous image processing, including multi-volume despeckle averaging and index-matching protocols applied to freshly euthanized specimens, this dual-system approach successfully achieved measurement-grade structural clarity and mitigated scattering artifacts. This validated imaging framework was subsequently applied to investigate the roles of gap junction (connexin) and hemichannel (pannexin) proteins in ocular development and structural maintenance. Quantitative biometry revealed distinct, channel-specific phenotypes. Depletion of the connexin gjd2b/Cx35.1 resulted in significantly reduced axial length and hyperopic shifts, whereas closely related Cx27.5 knockouts exhibited no structural biometric alterations. Investigations into the pannexin family demonstrated that both Panx1b and Panx2 deficiencies led to increased axial lengths and myopic shifts, with Panx2 knockouts also displaying marked lens epithelial malformations. Furthermore, a comprehensive longitudinal study of Panx1a mutants revealed a progressive structural decline characterized by axial myopia, age-related cataract-like lens texture change, epithelium lens defects, and significant retinal ganglion cell layer thinning. Ultimately, this research establishes a robust, non-invasive quantitative phenotyping methodology for small animal models. By directly linking optical instrumentation design to biological discovery, this work provides critical insights into the genetic regulation of ocular growth and integrity, establishing a strong structural foundation for future translational investigations into human visual diseasesItem type: Item , Access status: Open Access , Development of Novel Aerogel-Copper Composite Electrodes for Enhanced Electrochemically Mediated Amine Regeneration (EMAR) Based CO₂ Capture Using Photocatalysis(2026-07-24) Halim, Md. Akibul; Freire-Gormaly, MarinaElectrochemically Mediated Amine Regeneration (EMAR) is an alternative to thermal amine scrubbing because solvent regeneration is driven by electricity rather than heat. In EMAR, CO₂ absorbed by an amine solvent is released by electrochemically generated Cu²⁺ ions that compete with the amine for CO₂, enabling regeneration without heat input. However, practical systems remain limited by charge-transfer resistance and mass-transport constraints. This work investigates TiO₂ aerogel–modified copper foam electrodes for photo-assisted EMAR operation. TiO₂ aerogel powder was deposited on copper foam using APTES-assisted dip coating. Material structure and surface chemistry were characterized using SEM, XRD, XPS, BET, and μCT. Electrochemical performance was evaluated under dark and UV conditions. The three-cycle coated electrode (TCF3) showed lower regeneration energy and higher Faradaic efficiency than copper plate and bare copper foam electrodes. UV illumination enhanced electrochemical activity at lower current densities, demonstrating improved EMAR electrode performance.Item type: Item , Access status: Open Access , High Accuracy Thermal Characterization and Process Improvement for 3d-Printed Continuous Pitch Carbon Fibers(2026-07-24) Ali, Mouaz Mohammed; Kempers, RogerThis thesis investigates the development of high-thermal conductivity polymer composites through the process improvement of Continuous Pitch-based Carbon Fiber (CPCF) 3D printing. While previous research has identified CPCF as a viable solution for enhancing the thermal performance of 3D-printed parts, significant discrepancies exist between experimental results and theoretical predictions using the parallel model for composites. This research identifies and addresses the factors contributing to these discrepancies. First, a new fiber characterization methodology was established, comparing traditional microscopy with pycnometry to accurately determine the cross-sectional area and volume fraction of K13D2U fiber tows within the composites. Second, a high-accuracy thermal conductivity measurement apparatus was designed, calibrated, and validated. Furthermore, process improvements were implemented in the coating and printing processes to mitigate fiber breakage and maintain tow integrity. The implementation of these optimized processes resulted in the fabrication of a full-scale 3D-printed composite sample. Measurements conducted using a newly developed macro thermal conductivity apparatus demonstrated a significant improvement in thermal performance compared to prior studies, achieving a thermal conductivity of 36.63 W/mK at a volume fraction of 6.42%. While some deviations from the ideal parallel model remain due to inherent discontinuities within the fiber tow, this study contributes a validated framework for the precise fabrication and characterization of high-performance CPCF composites, offering a path forward for thermal management applications in additive manufacturing.Item type: Item , Access status: Open Access , Core-Shell Compound Droplet Impact on a Solid Surface(2026-07-24) Alkomy, Ismail Mohammad Hassan; Amirfazli, AlidadDroplet impact on solid surfaces controls critical outcomes in printing, coating, spray cooling, encapsulation and additive manufacturing, where both the impact regime and the maximum spreading factor, (i.e., β_max, that is the maximum coverage diameter the drop leaves on the surface normalized by its initial diameter), set footprint, coverage and material retention. In these processes, multicomponent core-shell droplets offer internal structure as an additional degree of freedom, yet their impact behavior is far less understood than that of single-liquid droplets. This thesis investigates the normal impact of millimetric core-shell droplets on smooth solid surfaces, with the aim of predicting impact outcome and β_max using a unified framework that combines experiments, an energy-balance model and machine learning. Experiments are performed with water and water-glycerol cores encapsulated by silicone oil shells of varied viscosity, while systematically varying impact velocity and core volume fraction. High-speed imaging is used to classify impacts into jetting, partial rebound, spreading-contact and their splashing counterparts, and to measure β_max. The data are expressed in a compact multicomponent non-dimensional space based on an equivalent Weber number that accounts for both external and internal interfaces, together with phase-specific Reynolds numbers for core and shell. On this foundation, a compound-droplet energy-balance model is formulated that treats β_max as the outcome of a global balance between initial kinetic and surface energies and viscous dissipation in core and shell, with separate scaling laws for each phase. The model predicts β_max accurately across the experimental parameter range and reveals how energy partitioning shifts with equivalent Weber number, core fraction and shell viscosity exploiting the comprehension of the underlying physics behind the process. In parallel, supervised machine learning models, trained on the same non-dimensional features, deliver high-fidelity predictions of both impact outcome and β_max, while interpretability analyses recover and even improve the dominant physical controls identified by experiments and the energy-balance model. Together, these three pillars demonstrate how internal structure in core-shell droplets can be exploited to manipulate impact behavior and provide predictive tools suitable for analysis and design.Item type: Item , Access status: Open Access , Predicting Business Angel Early-Stage Decision Making Using AI(2026-07-24) Katcharovski, Yan; Maxwell, Andrew L.External funding is crucial for early-stage ventures, yet business angel decision-making remains subjective and resource-intensive. The Critical Factor Assessment (CFA), a validated eight-factor venture evaluation framework, has demonstrated superior predictive accuracy over investors' own decisions. However, full evaluation requires multiple trained evaluators and several days per assessment, limiting adoption at scale. This study investigates whether AI can overcome these constraints. Multiple Large Language Models (LLMs) were prompted to assign CFA scores to 600 transcribed Shark Tank pitches with known deal outcomes. Machine learning classification models trained on the LLM-generated CFA scores achieved 85.0% accuracy in predicting deal/no-deal outcomes. The top-performing model (GPT-4.1-mini) exhibited very strong correlation with trained human evaluators (Spearman's ρ = 0.909, p < .001), substantially exceeding mean human–human agreement (ρ = 0.465). The integration of AI-based feature extraction with a validated decision-making framework yielded a scalable, reliable approach to early-stage venture evaluation.Item type: Item , Access status: Open Access , Evaluation and Identification of Promising CO2 Photocapture Materials(2026-07-24) Sahu, Tanay; O'Brien, Paul G.Anthropogenic CO₂ emissions demand rapid mitigation, yet prevailing capture technologies remain energy-intensive due to thermally driven regeneration. In direct air capture (DAC), dilute ambient CO₂ concentrations make regeneration the dominant cost driver. This thesis presents a materials-to-device framework for photo-assisted CO₂ capture, integrating density functional theory (DFT), fixed-bed breakthrough experiments, and machine-learning (ML) surrogates to link molecular mechanisms to reactor performance. DFT calculations on low-index transition-metal facets under controlled surface charge densities, a representation for photoexcited carriers, reveal that adsorption strength is strongly charge and composition-dependent, producing a photoswitch-like response where charge state governs adsorption versus desorption. A photo-assisted breakthrough reactor was subsequently developed using PEI-impregnated silica, with indirect solar-selective illumination yielding more uniform heating and faster desorption than direct in-bed lighting. Open-cell Cu, Al, and Ni foams were evaluated as conductive model substrates, achieving ~0.3–1.1 mmol m⁻² per cycle, with Ni exhibiting the highest gravimetric uptake. Illumination and applied DC bias produced reproducible desorption enhancements under isothermal conditions, supporting surface-charge modulation beyond bulk thermal effects. ML models trained on the DFT dataset achieved strong predictive accuracy (R² > 0.8), enabling scalable screening of alloy–facet–site candidates. These findings motivate hybrid reactor designs combining conductive metal foams with chemisorptive overlayers for energy-efficient, electroresponsive CO₂ regeneration.Item type: Item , Access status: Open Access , Design and Fabrication of Polyester-Based Bio-Based Adhesive Reinforced by Chitin Nanowhiskers(2026-07-24) Hsieh, Nathan Robert; Leung, Siu-NingThis thesis investigates the potential of chitin nanowhiskers (CNWs), a renewable bio-based nanomaterial, to enhance a commercial polyester (PE) resin (Bondo® Fibreglass Resin). Compared to epoxy systems, which are associated with sensitization, respiratory, and dermatological hazards during processing, polyester resins present comparatively fewer health risks, making them a suitable platform for sustainable adhesive development. The influence of CNW content, processing conditions, and dispersion methods was studied with respect to mechanical strength, adhesion, and thermal stability. Low CNW loadings (0.25–0.50 wt.%) improved strength, ductility, and heat resistance, while higher amounts led to clustering and reduced performance. Moderate heating improved dispersion and properties, whereas prolonged low-temperature processing weakened them. Among dispersion approaches, ethanol offered the most balanced improvements, while dry mixing gave stability but weaker interfacial bonding. Overall, the findings demonstrate that optimizing CNW incorporation can significantly improve polyester resin adhesives, supporting the development of stronger, tougher, and more sustainable alternatives to conventional materials.Item type: Item , Access status: Open Access , Microparticles Focusing Inside Rigid Zigzag Microchannels and Application to Bacteria Enrichment(2026-07-24) Refaei, Ahmed Ayman Mohamed; Rezai, PouyaSample preparation is vital for biomedical diagnostics, environmental monitoring, and food safety, with enrichment of microparticles and microorganisms essential for reliable detection. Label-free microfluidic enrichment offers a portable alternative to centrifugation and filtration, which require bulky equipment or external forces. Passive inertial microfluidics, particularly zigzag microchannels, enable efficient, high-throughput particle manipulation through Dean flow. However, knowledge gaps remain in understanding micrometer-sized behavior in rigid zigzag channels, evaluating design parameters, and predicting Dean drag velocity and force. This thesis systematically investigates rigid zigzag microchannels for focusing and enrichment. Objective 1 compared rigid (PMMA) and soft (PDMS) devices using microparticles (1-3.9 µm) and E. coli bacteria, showing superior focusing in rigid channels. Objective 2 employed COMSOL Multiphysics and Taguchi DOE to optimize geometry, achieving > 80% focusing efficiency. Objective 3 demonstrated enrichment of GFP-labeled E. coli with factors of 2.6 and 8 after one and two passes while preserving ~84% viability. This work establishes a robust, biocompatible platform with strong potential for portable diagnostics.Item type: Item , Access status: Open Access , Fluorometric Detection of Multiple Bacteria in Water Using Cell Imprinted Polymer Thin Films Integrated into a Microfluidic Channel(2026-07-24) Mahmoud, Islam; Rezai, PouyaWaterborne pathogens threaten public health, but standard detection methods—culture plating and molecular assays—are slow, laborious, and confined to centralized labs. Biosensors promise rapid, on-site monitoring, yet antibody-based designs demand cold-chain handling and are fragile. This thesis introduces a fluorescence microfluidic sensor built on whole-cell imprinted polymers (CIPs), offering a robust, reagent-free alternative for duplex detection in water. CIP thin films were formed in situ within microchannels by polymerizing around target bacterial cells, creating selective cavities. Multiple CIP regions on a single chip enable parallel capture of different species. After trapping cells, optimized FITC injection generates a fluorescence signal proportional to bacterial concentration. In singleplex tests with Salmonella, the sensor achieved a limit of detection (LOD) of 1.47 × 10³ CFU/mL, a limit of quantification (LOQ) of 5.28 × 10³ CFU/mL, and a linear response from 10³ to 10⁷ CFU/mL. Selectivity assays showed preferential Salmonella binding over non-targets. Duplex mode captured both Salmonella and E. coli concurrently at concentrations above 10⁵ CFU/mL. Although multiplexing reduced sensitivity, the CIP-based sensor requires minimal sample volume, no complex prep, and avoids cold storage, underscoring its field-ready potential. Future work will focus on polymer optimization, signal amplification, and validation with real environmental samples.Item type: Item , Access status: Open Access , Investigation of Airborne Transmission of Covid-19 and Other Transmissible Airborne Diseases in Airplanes, and Public Indoor Spaces Using Computational Fluid Dynamics and Spatiotemporal Risk-Maps(2026-07-24) Abu Raihan Ibna Ali; Freire-Gormaly, MarinaAirborne transmission through respiratory-generated aerosol is identified as one of the major causes of spreading infectious respiratory diseases such as COVID-19. Assessing the risks associated with virus-laden aerosol exposure in a high-density indoor environment is crucial for the risk mitigation of airborne contagious disease transmission. Identification of the most effective strategies is required for the mitigation of airborne disease transmission in the indoor environment. The Eulerian-Lagrangian method combined with two-way coupling was used to numerically obtain the aerosol transport, spatial distribution, and deposition information in indoor environments using Computation Fluid Dynamics (CFD). The study found that aerosol transmission is highly influenced by different factors such as escalator operational speed, ventilation configuration type, index passenger location, and number of outlets. The highly infection zones change accordingly. Further study is required to determine the impact of other associated factors with different intervention strategies.Item type: Item , Access status: Open Access , Investigation and Characterization of the Optical, Thermal, and Adsorption Properties of Carbon Aerogels for CO2 Capture Applications(2026-03-10) Heidari, Parham; O'Brien, Paul G.Climate change driven by rising atmospheric CO₂ concentrations has intensified the need for efficient, regenerable solid sorbents. Carbon aerogels are promising candidates due to their ultra-high porosity, low density, and tunable structure, yet their coupled optical, photothermal, and CO₂ adsorption behaviour as monolithic sorbents remains insufficiently characterized. This thesis investigates a disc-shaped carbon aerogel for CO₂ capture under flue-gas-like conditions to clarify how its radiative and thermal properties govern adsorption performance and photothermal regeneration. The aerogel was characterized using UV–Vis–NIR and FTIR spectroscopy to measure reflectance, transmittance, and absorptance across the solar and thermal-infrared ranges. Mid-wave infrared thermography under a xenon arc lamp (1 Sun irradiance) quantified transient heating and cooling. Dynamic breakthrough experiments with a 11% CO₂ / 89% N₂ mixture at 25 °C, followed by photothermal desorption at 110 °C, were performed to determine CO₂ capacity and regeneration performance. Optical measurements showed negligible transmittance and low reflectance from the ultraviolet through the mid-infrared, corresponding to broadband absorptance generally above 0.9 and high effective emissivity in the thermal-imaging band. Under 1 Sun illumination, the surface temperature rose from ~28 °C to ~64 °C within 1–2 min and cooled rapidly back toward ambient once the light source was removed, indicating efficient radiative heating and low thermal mass. Breakthrough measurements yielded a net CO₂ adsorption capacity of 1.88 mmol g⁻¹ and a photothermal desorption capacity of 1.14 mmol g⁻¹, with good reproducibility but partial hysteresis between adsorption and desorption. Overall, the results demonstrate that carbon aerogels can combine meaningful CO₂ uptake with favourable photothermal characteristics, making them strong candidates for radiatively driven temperature-swing adsorption processes. The work provides a quantitative baseline for future material design, further characterization, and reactor-level optimisation of carbon-aerogel-based CO₂ capture systemsItem type: Item , Access status: Open Access , What limits the greater adoption of 3D printing in Canada? Identifying the Barriers to the Adoption of 3D printing in Canada(2026-03-10) Di Scipio, Nicholas; Maxwell, Andrew L.Despite significant advances in materials, equipment, and applications, the adoption of 3D printing in Canadian manufacturing remains limited, with most firms restricting its use to prototyping rather than full-scale production. This thesis investigates why this gap persists by examining the economic, technical, organizational, and cultural factors shaping adoption decisions. Drawing on semi-structured interviews with industry stakeholders across manufacturing firms, suppliers, and supporting organizations, the study combines empirical insights with established technology adoption theories, including the Technology Acceptance Model, Diffusion of Innovation, and the Product Adoption Process. The findings show that slow adoption is not driven by technical limitations alone. Instead, adoption is influenced by interconnected perceptions of risk, cost, capability, and organizational readiness, reinforced by conservative decision-making cultures, limited internal expertise, and uncertainty around qualification and certification. Customer expectations related to lead time, customization, and reliability further shape adoption behavior, either accelerating experimentation or reinforcing risk aversion. Regional infrastructure differences and ecosystem maturity also affect firms’ ability to progress beyond trial use. Based on these findings, the thesis proposes a synthesized adoption framework that captures adoption as an iterative, feedback-driven process rather than a linear sequence. The framework integrates individual perceptions, organizational conditions, and external pressures to better reflect real-world adoption dynamics. This research contributes a practical and theoretically grounded lens for understanding 3D printing adoption in Canada and provides a foundation for future research, policy development, and industry strategies aimed at supporting broader and more sustained adoption.Item type: Item , Access status: Open Access , Photothermal Lateral Flow Assay with Inertial Microfluidic Enrichment for Early Detection of E. coli in Urinary Tract Infections(2026-03-10) Ghazi, Yasaman; Rezai, PouyaEscherichia coli is the leading cause of urinary tract infections (UTIs), yet rapid and specific diagnosis at the point of care remains challenging. Conventional diagnostic methods, including urine culturing and microscopy, are time-intensive, require trained personnel, and often lack specificity for E. coli, limiting their effectiveness in resource-limited or time-critical settings. While lateral flow assays (LFAs) offer simplicity and portability, their clinical utility is constrained by a high visual limit of detection (LOD). This thesis presents an integrated diagnostic platform that combines passive microfluidic bacterial enrichment with photothermal detection to significantly improve LFA sensitivity for UTI diagnostics. Bacterial preconcentration was achieved using viscoelastic forces generated by flowing polyethylene oxide (PEO) solutions through custom-fabricated PDMS microchannels with straight, symmetric zigzag, and asymmetric zigzag geometries. Optimal enrichment was obtained in a straight 25 µm × 25 µm channel operated at 2 µL/min with 1000 ppm PEO, resulting in approximately an order-of-magnitude increase in bacterial concentration through sample volume reduction while retaining target cells. In parallel, a photothermal detection approach based on lock-in thermography was developed to detect temperature modulations arising from nanoparticle–target interactions on LFA test and control lines. This method enabled quantitative signal extraction beyond visual inspection and provided an additional two-order-of-magnitude sensitivity enhancement. Together, the integrated enrichment and photothermal detection platform achieved an overall ~1000-fold sensitivity improvement compared to standard visual LFAs. These results demonstrate the strong potential of combining passive microfluidic preconcentration with photothermal readout for rapid, sensitive, and reliable point-of-care UTI diagnostics. Identified limitations include manual operation, reliance on desktop-based processing, and pressure constraints of PDMS microchannels. Future work should focus on validation with clinical urine samples, platform automation with onboard fluidic and signal processing, evaluation of rigid microchannels for higher-pressure operation, and extension to additional bacterial pathogens and diagnostic applications.Item type: Item , Access status: Open Access , Development of Emissive Porous Polymers and Parabolic Trough Underside Reflectors for Enhanced Radiative Cooling(2026-03-10) Chiu, Po-Chun; O'Brien, Paul G.A trough-enhanced radiative cooling (RC) system was developed and experimentally evaluated to achieve high-efficiency passive cooling under real outdoor conditions. Polymer-based porous PVDF-HFP emitters with high solar reflectance and strong atmospheric emittance were fabricated and integrated with parabolic trough reflectors. Monte Carlo ray tracing and heat balance simulations were conducted to predict temperature performance under various solar irradiance and convection scenarios. The experimental results revealed stable sub-ambient cooling of 1.2–4.2 °C during the day and up to 4 °C at night, demonstrating consistent cooling even under partial cloud coverage. Numerical predictions agreed well with measurements, showing less than 1 °C deviation, indicating the model’s reliability in evaluating RC performance. The validated model enables predictive design and optimization of trough-integrated RC systems, while the findings highlight the potential of reflective geometries in enhancing cooling power and scalability for energy-efficient thermal management and sustainable building applications.Item type: Item , Access status: Open Access , Development of a Self-Heating Consolidation Procedure for 3D-Printed Continuous Wire Polymer Composite Laminates(2026-03-10) Barbuio, Thomas John; Melenka, Garrett; Kempers, RogerThe voids in 3D-printed continuous wire polymer composites (CWPCs) reduce the wire-polymer adhesion, which can decrease their strength and stiffness and their in-part sensing accuracy. This thesis shows the development, implementation and effects of a consolidation procedure to reduce the voids in unidirectional and cross-ply 3D-printed CWPC laminates. The consolidation procedure used resistive heating combined with hot-pressing to reduce the internal voids. Image processing of sample cross sections proved the void content in consolidated samples were 91.6% lower compared to unprocessed, while flexural tests found 5% and 12% higher flexural strength and stiffness respectively. Next, the effects of the consolidation procedure were tested on the uniaxial tensile properties of unidirectional and cross-ply 3D-printed CWPC samples, showing promising results for transverse reinforced CWPC samples. The results of the two studies performed showed that the consolidation procedure significantly reduces the void content of the samples, and thus positively impacts the mechanical properties.Item type: Item , Access status: Open Access , Laser-Carbonized Graphene and Lignin Films for Sustainable Transient RFID Electronics(2025-11-11) Khan, Juveiria; Rizvi, RezaThe growing problem of electronic waste calls for new materials that are sustainable and easy to recycle. This thesis focuses on developing conductive films for transient and flexible electronics using two different material systems. In the first part, cellulose paper was used as a biodegradable base. Three types of coatings were prepared: (i) graphene oxide (GO), (ii) GO with ascorbic acid (AA) as a reducing agent, and (iii) GO with a mixture of ascorbic acid and sodium lignosulfonate (Na-Lgs) to provide extra carbon content. After coating, the samples were treated with a laser to create conductive patterns directly on the cellulose. This study shows that cellulose can serve as a compostable material for electronics while still offering useful electrical properties. In the second part, polyethylene terephthalate (PET) films were coated with compressible flow exfoliated (CFE) graphene. PET provided strength and flexibility, while the graphene coating gave an initial conductivity that was further improved by laser carbonization. The PET/CFE system achieved very low sheet resistance, with the best value recorded at 16.17 Ω/sq, showing excellent electrical performance compared to many earlier studies. To evaluate both systems, several techniques were used: SEM to study the surface and cross-section of the films, TGA to test thermal stability, Raman spectroscopy to analyze graphitic structure, FTIR to confirm chemical changes, and sheet resistance measurements to check electrical performance. Overall, the results show two promising directions: cellulose-based films for biodegradable and eco-friendly devices, and PET/CFE graphene films for high conductivity and robust performance. In particular, the PET/CFE graphene system, with its low sheet resistance, shows strong potential for further development towards commercial RFID tags and other high-performance flexible electronic devices.Item type: Item , Access status: Open Access , Automated Micro-CT Image Segmentation and Void Analysis of HDPE-HGM Syntactic Foams Using Machine Learning(2025-11-11) Shiv Shankar, Riya Vasan; Melenka, Garrett; Rivzi, RezaSyntactic foams are a subclass of composite materials in which the matrix is embedded with hollow microspheres, offering a high strength-to-weight ratio suitable for the aerospace, marine, and automotive industries. The microspheres create porosity, visually indistinguishable from voids caused by manufacturing during imaging, both of which influence mechanical performance. Quantification and classification are, therefore, crucial for quality control and predictive modelling. This thesis proposes an integrated pipeline utilizing micro-CT imaging and unsupervised learning to segment and quantify voids, particles, and matrix in HDPE-HGM syntactic foams. A hybrid segmentation technique leveraging slice-wise thresholding and K-means clustering resulted in an F1 score of 0.92 compared to LabKit for voids. Voids were further classified into raster voids and HGM cavities based on shape descriptors, with subsequent spatial analysis performed using the R-index and clustering coefficients. Morphological features were correlated to Ultimate Tensile Strength and Young's Modulus. A custom GUI enables 3D visualization and segmented mesh export, facilitating the creation of digital twins for enhanced material analysis and process optimization.Item type: Item , Access status: Open Access , Electrochemical Microfluidic Sensors with Integrated Ion-Selective Polymer Membranes for the Detection of Trace Ions in Water(2025-11-11) Oseyemi, Ayobami Elisha; Rezai, PouyaThere is an increasing demand for low-cost, portable, and sensitive sensing technologies for detecting trace levels of metal ions in water to support public health, environmental monitoring, and energy applications. Traditional analytical methods, while accurate, are limited by their reliance on bulky equipment, high cost, and complex electrode modification, making them unsuitable for real-time or on-site use. This research addresses these limitations by developing a microfluidic electrochemical sensor platform that integrates in-situ synthesized, stand-alone ion-imprinted polymer (IIP) membranes for the selective detection of sodium (Na⁺), lead (Pb²⁺), and lithium (Li⁺) ions in water. The study employed a stepwise methodology: an ion-selective polymer membrane was first developed to detect salinity, achieving a 28-fold sensitivity improvement and a detection limit of 0.45 ppm. Next, a Na-IIP membrane using 15-crown-5 as an ionophore achieved 58 ppb detection with over threefold sensitivity enhancement. Finally, Pb-IIP and Li-IIP membranes were developed, attaining detection limits of 7.3 ppb and 168 ppb, respectively, with high selectivity over competing ions. All configurations demonstrated high reproducibility, multi-ion selectivity, and recovery rates ranging from 69% to 109% in municipal tap water. The stand-alone membrane design simplifies fabrication, enhances stability, and is compatible with continuous-flow operation. This work advances the development of scalable, point-of-need sensing systems and offers a foundation for future multiplexed and automated water quality monitoring platforms.Item type: Item , Access status: Open Access , Low Reynolds Number Settling of Cylindrical Rods with Various Geometries in a Quiescent Fluid(2025-11-11) Hamidi, Amirhossein; Hanson, RonaldThis dissertation is motivated by the atmospheric transport of microplastic fibres, a growing environmental concern. The atmosphere is recognized as a major pathway for the long-range transport of microfibres. However, many atmospheric simulations simplify fibre geometry, often representing them as volume-equivalent spheres or straight cylinders, despite the more complex shapes observed in microfibre samples from atmospheric deposits. This research aims to enhance our understanding of the settling behavior of curved, V-shaped, U-shaped, and S-shaped cylindrical rods within the Reynolds number and aspect ratio range associated with the atmospheric transport of microfibres. A series of experiments were conducted using millimeter-scale metal rods with aspect ratios ranging from 10 to 120, settling in a quiescent water-glycerin chamber to replicate Reynolds numbers below 7. A stereo-PTV system was employed, with two side cameras tracking terminal settling velocities and orientations, while a bottom camera captured potential spinning motions. Using a three-dimensional calibration algorithm, the terminal velocities and orientations of the rods were determined in real-life space. Results demonstrate that curved and V-shaped rods settle faster than straight rods of the same dimensions, with V-shaped rods settling only slightly faster than curved rods of equivalent projected length. U-shaped rods exhibit a transition in orientation from vertical to oblique above a critical Reynolds number or below a critical middle arm length ratio. They consistently settle faster than straight rods because of their non-zero inclination angle. Furthermore, their terminal velocity either peaks at a specific aspect ratio or remains constant due to a trade-off between side arm length and rod inclination. S-shaped rods exhibit spinning motions at a constant rate while settling at the same velocity as the straight rods of identical dimensions. Their spinning rate peaks at an intermediate middle arm length ratio, which was experimentally and theoretically investigated. New models were developed to estimate the terminal velocity of rods with these geometries, which can also be applied to predict the terminal velocity and the horizontal travel distance of microfibres of various shapes. This study highlights the crucial role of fibre morphology in determining vertical terminal velocity and, consequently, horizontal dispersion in the atmosphere.