Thesis
Optimising temperature and electromagnetic sensing using nanodiamonds and fluorescence microscopy
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2023
- Thesis identifier
- T16594
- Person Identifier (Local)
- 201867282
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- The motivation behind this research project was to add the capability of magnetic field and temperatures sensing using nanodiamonds as an all-optical probe in biological systems. Fluorescent nanodiamonds are an exciting prospect for use as an optical sensor within the field of biology. Not only does their small size (5 nm - 100 nm) allow them allow the targeting of micro-structures and organelles within single cells, but they have also been shown to be non-cytotoxic. Coupling these characteristics with optically stable fluorescent defects within the diamond structure, fluorescent nanodiamond could be used as a long-lived all optical sensor for investigating sub-cellular environments without impacting or impairing the ordinary function of the cell. The aim of the project was to introduce the ability to perform optically detected magnetic resonance spectroscopy (ODMR) measurements of an ensemble of nitrogen-vacancy (NV−) defect centres within nanodiamond crystals, with the aim of refining the magnetic and temperature sensing measurement protocols for use in biological systems. Initial experiments revolved around implementing the well established ODMR measurement regime for use in our confocal system. In this investigation, I discovered that ring resonators were are suitable for use in our experimental set-up, as the oil-immersion objective grounded the microwave field generated, limiting the contrast of the ODMR measurement to under 1% across the region in which a uniform microwave field is produced. More effective for ODMR spectroscopy proved to be the combination of the coplanar waveguide and copper micro-wire antenna for microwave delivery to the sample, regularly resulting in ODMR contrast greater than 10%. I also explored the measurement parameters that can effect the sensitivity of the NV− centres to an static magnetic field. Throughout this investigation, and optimising the applied excitation and microwave power, I was able to achieve a maximum DC magnetic field sensitivity of 1.13 ± 0.04 µT/√Hz. In the pursuit of the temperature sensing capability of the NV− centre, I attempted to perform ODMR measurements using the Oko-Labs 301-H temperature stage. The stage was incompatible with our measurements owing to the large sample drift observed when the stage was in operation. This drove the development of an ODMR with Referencing measurement scheme that allowed us to compensate for the effects of measurement drift across an experiment. This measurement technique proved to be very powerful and was able to allow for accurate determination of the resonant microwave frequency of the NV− centre even when faced with 15% loss in fluorescent signal due to drift across the ODMR spectra. Further development of the NV− thermometry protocol was made with the introduction of a multi-point measurement scheme that had been outlined in literature. The introduction of this measurement scheme still allowed for the measurement of temperature using the ODMR spectra from an NV− ensemble, despite using just four applied microwave frequencies. In the absence of a suitable environment chamber, I developed a measurement protocol to simulate the effects of a temperature change on the measured ODMR spectra of the NV centre. With this measurement protocol, I was able to compare and contrast three different multi-point ODMR thermometry analysis schemes that had been presented in literature. Finally, I was able to test the ODMR measurement protocols developed throughout this project on nanodiamonds inside Macrophage and THP1 cells. In these experiments I showed that our confocal system is capable of measure the effect of an applied magnetic field and simulated temperature change on the ODMR spectra of a nanodiamond embedded within biological material. In the case of the simulated temperature change experiments, we were able to determine that the measurement scheme first presented by Fujiwara et al in [1] is the most effective measurement scheme for monitoring temperature changes using our measurement system and biological samples.
- Advisor / supervisor
- Patton, Brian
- Resource Type
- DOI
Relazioni
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PDF of thesis T16594 | 2023-06-05 | Pubblico | Scaricare |