Novel metal oxide for sensing, taking advantages of external fields

This PhD thesis explores the development and study of new metal oxide materials, including indium tin oxide (ITO) and nickel ferrite (NiFe₂O₄) spinels, for advanced biosensing, using tools like muon spin relaxation (μSR) experiments to tap into their potential. The main goal was to create metal oxides with special features—oxygen vacancies, sulfur doping, and surface changes—to boost their magnetic, electronic, and catalytic abilities for fast, affordable biosensors. We aimed to tackle disease detection challenges, especially for SARS-CoV-2, by using external fields to understand and improve how these materials work at a microscopic level. Our work shows that bare ITO can act as a biosensor part component to spot detect SARS-CoV-2 antibodies by using catalytic reactions to shift surface resistance, leading to a low-cost, quick electrical biosensor checked with resistance tests. We also looked at ITO in a new way in Chapter 3, reviewing computer-based studies on how surface tweaks—like adding certain molecules—improve its catalytic power, giving us ideas to make it even better. Then, we made non-stoichiometric NiFe₂O₄ with oxygen vacancies by changing the iron-to-nickel mix using a co-precipitation method, and μSR showed it had both ferrimagnetic and superparamagnetic traits. To push NiFe₂O₄ further, we added sulfur to create porous microcage structures, and μSR revealed better biosensing in tricky complex fluids like fetal bovine serum (FBS). External fields, especially μSR at TRIUMF, were key here. These facilities allowed us to explore the materials’ magnetic properties, showing shifts from ferrimagnetic to superparamagnetic states as temperature and sulfur content rose. This helped us evaluate how defects shape material behavior, steering us toward better sensor designs. Tests showed sulfur-doped NiFe₂O₄ beat ITO at picking up antigens, thanks to oxygen vacancies and charge movement effects. Future work will focus on optimizing defect concentrations, miniaturizing devices, and exploring energy storage applications. This thesis establishes a foundation for defect-engineered metal oxides, using external fields like μSR to unlock their potential in healthcare and beyond, offering a pathway for innovative sensing technologies.

Grantor dc:publisher

University of Guelph

Author dc:creator

• Fattahi, Arash

Advisor dc:contributor.advisor

• Ghandi, Khashayar

• metal oxide
• biosensor
• muon spin spectroscopy

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10214/29528

OAI record oai:identifier

https://atrium.lib.uoguelph.ca/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aatrium.lib.uoguelph.ca%3A10214%2F29528