Browsing by Author "Birss, Viola Ingrid"

Now showing 1 - 6 of 6
  • Thumbnail Image
    ItemEmbargo
    Aqueous Chemical Solution Deposition of Epitaxial Lead-Free Ferroelectric Sodium Potassium Niobate (KNN) thin films
    (2023-05-12) Mohammed, Ahmed Zaher; Dolgos, Michelle; Birss, Viola Ingrid; Shi, Yujun; Roberts, Edward; Shimizu, George
    Potassium Sodium Niobate (KxNa1-xNbO3, KNN) thin films were fabricated on SrTiO3 (STO) substrates using an environmentally friendly aqueous Chemical Solution Deposition (CSD) approach, employing water-soluble Na, K, and Nb polyoxometalate precursors. This green route for KNN thin film fabrication offers reduced environmental impact and potential industrial scalability. The annealing recipe was optimized through a detailed investigation, finding that a one-minute annealing at 700°C after each deposition yielded the best structural properties. The impact of varying the K+/Na+ stoichiometry on the films' structural properties was systematically examined. The investigation demonstrated a trend between the K+/Na+ molar ratio in the precursor solution and the strain-state and lattice parameters of the resulting films, suggesting adding 50% excess potassium in the precursor solution is promising for optimal ferroelectric performance. Leveraging the versatility of the aqueous synthesis, lithium was incorporated as a dopant in the precursor solution. Different Li concentrations were investigated, and it was determined that a 6% Li concentration improved the films' structure compared to undoped samples. This demonstrates the potential of aqueous deposition for incorporating dopants to enhance material properties. The study further highlighted the potential for strain engineering and additional dopant incorporation using the aqueous CSD method, opening up avenues for further exploration and optimization of KNN thin films' properties.
  • Thumbnail Image
    ItemOpen Access
    Dielectric Thin-Films for Improving the Durability of AC Electrothermal Microfluidic Devices
    (2024-08-21) Cenaiko, Stirling Autumn; Dalton, Colin; Birss, Viola Ingrid; Natale, Giovanniantonio
    Microfluidic devices such as lab-on-a-chip, organ-on-a-chip and micro-total analysis systems allow for fast and precise testing of biofluids but can be limited in their capacity to perform more complex tests with currently available particle and fluid manipulation methods. Electrokinetics offers a way to precisely control particles and fluids using electric fields without the use of moving parts such as valves and diaphragms. Electrokinetics mainly includes dielectrophoresis, electroosmosis and electrothermal phenomena. Devices using these phenomena are limited in the voltage that can be applied, as higher voltages, along with higher fluid conductivities, significantly increase the risk of electrolysis and electrode degradation due to electrochemical reactions. AC electrothermal (ACET) is the most effective electrokinetic technique for pumping and mixing high conductivity fluids (including many biofluids, such as blood and urine). This thesis investigates the simulation and fabrication of dielectric thin-films for improving the durability of ACET micropump electrodes. RF-sputtering was investigated as a means to produce high-permittivity thin-film dielectrics. RF-sputtering is a widely-available method to coat high purity thin-films. Sputtering parameters (including power, oxygen content and temperature) were investigated to determine their impact on the deposition of metal oxides. This work also uses simulations to investigate the influence of spatially variant electrical phases on ACET fluid velocity, as well as simulating the dielectric coating effectiveness. This work showed that RF-sputtering can cause significant damage to the materials used for the microelectrodes of ACET devices. However, utilising certain process parameters, RF-sputtering can successfully be used as a method to deposit high-permittivity dielectrics to decrease degradation of ACET electrodes at higher applied voltages. These dielectric coatings may be applied to other forms of electrokinetic devices to improve their longevity and electrochemical stability.
  • Thumbnail Image
    ItemOpen Access
    Evaluating Innovative Electrochemical Systems in the Energy Sector with Life Cycle Assessment
    (2024-07-04) Nishikawa, Emily; Bergerson, Joule A.; Birss, Viola Ingrid; McCoy, Sean Thomas; Ponnurangam, Sathish; Sinton, David Allan
    Innovative technologies such as carbon conversion technologies, drop-in fuel production, and automotive batteries are being developed to reduce greenhouse gas emissions. However, assessing the potential emissions of these emerging technologies presents significant challenges. This thesis explores how assessment frameworks can be adapted to effectively evaluate these new solutions by expanding boundaries, functional units, feedstocks, and metrics to support more informed decision-making. Life cycle assessment (LCA) studies typically evaluate systems with defined products, which may not apply to emerging technologies. These studies often limit assessments to known components, such as intermediate products in cradle-to-gate studies. The first part of the thesis expands the boundary to cradle-to-grave by proposing potential markets or uses for the intermediate products. Additional insights are provided, facilitating and encouraging technology developers to apply LCA even at early development stages. In other cases, emerging technologies and novel resources nearing deployment, such as lithium production and refining in North America, have been scarcely studied for their potential environmental impacts. Alternative battery technologies such as sodium-ion batteries are also being explored, which is assessed in the context of competition with lithium-ion batteries. A hybrid functional unit that includes considerations of the use phase of both lithium and sodium batteries is employed to avoid completely excluding the use phase as commonly seem in comparative assessments. The second part of the thesis demonstrates that including design parameters for battery use offers a broader context for evaluating competition among different battery technologies. The final part of this thesis focuses on deployment decisions, using aviation fuel production as a case study. This area presents numerous feedstock and technological pathway options. The scope is expanded to consider both types of feedstocks typically studied separately (biomass and CO2) and adapts an iterative framework to include complementary metrics (production cost and supply risks), leading to a more comprehensive assessment and more effective decision-making. This thesis addresses the challenges of assessing emerging technologies. The findings emphasize that LCA modeling choices strongly influence conclusions. Expanding boundaries, considering alternative pathways, and incorporating related key metrics offer additional insights for comprehensive assessments and informed decisions regarding emerging technologies.
  • Thumbnail Image
    ItemOpen Access
    Methodological Analysis of an Improved Gluten Quantitation Aptamer-based Biosensor
    (2022-09-22) Kuri Martinez, Juan Carlos; Yadid-Pecht, Orly; Turner, Raymond J.; Murari, Kartikeya; Birss, Viola Ingrid
    Fluorescence resonance energy transfer based aptamer are currently being studied in many research groups due to their potential contribution as an alternative gluten standard for gluten- quantitation. The current gold standard withholds critical limitations due to the nature of the system, hence this aptamer-based sensor (or aptasensor for short) application represents one of the alternatives; yet, drawbacks such as low signal-to-noise ratio and reliability are in the scope of research groups aiming to overcome them. In this study, multiple variations of the protocol are assessed based on correctly classifying food samples as their actual concentration of gluten, this is coined as the accuracy of the biosensor. The study also aims to overcome the current limitation of the gold standard in fermented samples by including soy sauce and malt vinegar in the tests. And different additives aiming to help overcoming the limitation were implemented into the protocol and assessed. This approach allowed the biosensor to classify the products with 98.28% of accuracy, and 0% of error in classifying gluten-rich products (false-negatives) within the first 3 days of bioassay preparation; yet, this bioassay needs to be studied further as only 18 different off-the-shelf products were tested (over 800 tests in total). Additionally, after the first week, false-negatives increased to around 5% and remained that way until the end of the first month. The cause of this relies mostly on the decomposition of the conjugate reduced graphene oxide and polyethylene glycol that are implemented in the system. This implies that further research aiming solely at additives or alternative reagents that increase the lifespan or stability of the conjugate would augment the overall performance.
  • Thumbnail Image
    ItemEmbargo
    Study of Electrochemical Methane Oxidation to Oxygenates
    (2024-04-10) Al-Attas, Tareq Ali Salem; Kibria, Md Golam; Thangadurai, Venkataraman; Karan, Kunal; Roberts, Edward (Ted) PL; Birss, Viola Ingrid; Morales Guio, Carlos Gilberto
    Methane (CH4), a primary component of natural gas, plays a vital role in energy and chemical production. However, conventional methods of chemical production tend to be resource-intensive and often result in the release of CH4 through venting or flaring in oil and gas operations. Decentralized technologies that leverage renewable energy can mitigate CH4 emissions while generating revenue. Electrochemical oxidation of CH4 (eCH4OR) into valuable fuels and materials offers a flexible solution that can operate in varied conditions. Nevertheless, achieving desirable outcomes at scale is challenging due to the high energy requirements for breaking the C–H bonds of CH4. This thesis focuses on developing catalysts for high-rate and selective electrooxidation of CH4 while also aiming to deepen our understanding of the reaction mechanism. Drawing inspiration from iron (IV)-oxo (FeIVO) metalloenzymes that activate C–H bonds, a copper-iron-nickel (CuFeNi) catalyst for selectively oxidizing CH4 into formate using a peroxide-assisted pathway is presented. The synergistic effect of the metals to selectively oxidize CH4 is explored by in situ spectroelectrochemical studies (i.e. XANES and UV-Vis) and density functional theory (DFT) calculations. Specifically, the analyses revealed the presence of high valent FeIV as the active site for CH4 oxidation, attained by the reactive oxygen species generated during the partial oxidation of H2O2 at low overpotentials compared to water oxidation reaction (OER) on nickel. Furthermore, the critical role of copper in preventing the overoxidation of valuable oxygenates to CO2 was revealed. We achieved a formate faradaic efficiency of ~42% at a current density of 32 mA cm−2 (i.e., partial current of ~13 mA cm−2) and a low applied potential of 0.9 VRHE. Additionally, the thesis examines the reaction pathways of the eCH4OR using hematite (α-Fe2O3) as an electrocatalyst. Different electrochemical and in situ spectroelectrochemical techniques, including ATR-SEIRAS, EIS, and PTR-TOF-MS, were employed to comprehend the mechanism of this reaction. The electrochemical oxidation current density uncovered non-faradaic adsorption of CH4 molecules at lower applied potentials. The non-faradaic adsorption of CH4 molecules was further confirmed through ATR-SEIRAS. In situ ATR-SEIRAS also revealed the presence of the FeIVO species and CH4 oxidation intermediates, correlating them with the applied potential. Thisanalysis unveiled the formation of oxygenated products, including CH3OH, HCOOH, CH3COOH, and their corresponding intermediate adsorbed species, such as •OCH3, •OCOH, and •OCOCH3. Notably, C–C coupling between –COCH3 and –CH3 via ketonization resulted in CH3COCH3 formation. PTR-TOF-MS supported our findings by confirming that acetone is the primary liquid product generated, achieving a faradaic efficiency of 6.3% at 2.3 VRHE. This result is attributed to its formation by coupling acetate and formate intermediates. Consequently, we developed proposed reaction pathways for the selective electrooxidation of CH4 to C1-C3 products. The thesis extends to present techno-economic and life-cycle assessments of electrification options for CH4 utilization. Initially, the study highlights the economic viability of electrifying reformers and boilers in traditional technology. A futuristic scenario discusses one-step methanol synthesis via the direct eCH4OR and illustrates the impact of cell voltage and electricity prices on the calculated minimum selling price of methanol. For instance, methanol production can be profitable at electricity prices below ¢4 per kWh at a total operating cell voltage of 2.0 V. The analysis establishes electricity emission goals to maintain net CO2 emissions within the acceptable range for current methanol synthesis. It is shown that the emissions intensity of the electricity source must be under 181 kgCO2 per MWh for the electrochemical route.
  • Thumbnail Image
    ItemOpen Access
    The Electrochemistry of Ferrocenyl-thiolate Self-Assembled Monolayers for use in a Toll-like Receptor 4-based sensor
    (2021-08-20) Singh, Raunak; Birss, Viola Ingrid; MacCallum, Justin Laine; Sutherland, Todd Christopher
    Detection of biological agents by traditional bench-top instrumentation is insufficient for purposes of real time on-site analysis, which is imperative for biodefense applications. Unlike radiological and chemical warfare agents, sophisticated detection systems have not yet been designed for immediate sensing of biological agents. Development of field-deployable biosensors is a response to fulfill this gap, specifically, the demand for immediate recognition of samples of unknown origin requiring broad-based detection capabilities. Our research group has been pursuing this venture by creating an electrochemical biosensor that is able to detect the bacterial endotoxin, lipopolysaccharide (LPS), produced by gram negative bacteria. Our biosensor utilizes Toll-like Receptor 4 (TLR4) immunoproteins as the biorecognition element. These immunoproteins are surface immobilized via ternary alkanethiolate self-assembled monolayers (SAMs) deposited on polycrystalline Au surfaces. These SAMs possess a uniquely low interfacial resistance (? 1 k?) due to the presence of a Ferrocenyl-thiolate component, which mediates electron transfer from dissolved Fe(CN)64- to the underlying Au substrate. The work presented in this thesis focuses on the problem, and its subsequent solution, encountered with the SAM electrochemistry portion of the TLR4 sensor assembly. The issue was initially detected by false positive responses of the sensor in the absence of LPS-containing bacterial lysate, exhibiting an increase in resistance of similar intensity in both the absence and presence of heat-killed Salmonella typhimurium (HKST) bacterial lysate. The primary cause of the TLR4 sensor drift was determined here to be the instability of the Fc+ group, which is generated repeatedly during the mediation of the Fe(CN)64- oxidation process. This is consistent with past literature that alluded to the irreversible redox deactivation of the Fc+ group under non-optimal conditions. This problem was remedied in this work by replacing phosphate ions from the buffer solution by perchlorate, but as proteins such as TLR4 should be kept in neutral conditions, another solution was sought. This involved replacing the original Fc-thiol molecule (i.e., 11-mercaptodecyl-ferrocenylcarboxamide (Fc-amide)) with 11-(ferrocenyl)undecanethiol (FcC¬11).These novel ternary SAMs containing the stable FcC11 component were then used to prepare a new generation of TLR4-based sensors, which showed negligible drift and were able to reliably detect LPS from 0.0128 to 5000 µg/mL. This demonstrates that utilizing Fc-thiolate SAMs is now a viable method to prepare low-resistance biosensors for use as field-deployable systems.