Implementation of DAQ/FPGA electronics and control software for Optically Detected Magnetic Resonance (ODMR) experiments on a widefield microscope

• Autor(a) principal: Teixeira, Ana Amélia Carvalho
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10348/11951
• topic: ODMR; widefield fluorescence microscopy

The main objective of this thesis is to develop and test the experimental upgrade of a wide-field fluorescence microscope that will allow optically-detected magnetic resonance (ODMR) experiments to be performed at optical centers in diamonds, known as NitrogenVacancies (NVs). The optically detected magnetic resonance technique may be used as a non-invasive magnetometry technique. Magnetic field detection applications may involve NVs implanted in diamond or fluorescent nanodiamonds. Both of these samples are compatible with the upgraded ODMR setup developed in this thesis. In the future, the ODMR wide-field microscope could be used to investigate magnetic nanostructures with applications in cancer treatment such as magnetic nanoparticles, and in medical research, especially in neurosciences. The NVs in diamond create highly fluorescent color centers, which are the basis of the ODMR technique. By using fluorescent nanodiamonds, the NVs can be localized in close proximity to specific organelles or axons, where temperature or magnetic field measurements are relevant. This thesis describes the implementation of the necessary hardware, such as the microwave generator, the field programmable gate array, and its synchronization with an EMCCD detector implemented in a device control software developed in Python 3.10. Testing of the developed setup included running OMDR experiments on two types of diamond samples. First, a nanodiamond sample was visualized and the ODMR signal was further analyzed in selected regions of interest where a single or a cluster of nanodiamonds are present. Next, a diamond with a uniform layer of NVs at a depth of 5 nm from the surface, was used. Two areas of the diamond could be identified, an area with magnetic nanoparticle agglomerates and an area of magnetic nanoparticle hybrids, where superparamagnetic nanoparticles are protected within a Wax matrix. ODMR experiments in the presence and absence of an external magnetic field were performed for both particles to distinguish their magnetization. In summary, the addition of an ODMR upgrade has been successfully integrated into a wide-field total internal reflection fluorescence (TIRF) microscope, which allows simultaneous collection of ODMR characterization across the entire field of view. Its magnetic field sensitivity is discussed and compared with state-of-the-art ODMR implementations in confocal microscopy settings using ODMR traces collected on two types of diamond. The simultaneous magnetometry, once optimized, may provide a relevant tool for the study of neuronal networks.