Characterization of nanoparticles with optical fluidic cavity
<p>The optical trapping of nanoparticles and biomolecules has recently attracted considerable attention as a means for the manipulation and characterization of target analytes. Nano-particulate pollutants and microbiological organisms, such as viruses, have optical characteristic signatures ba...
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| Format: | Thesis |
| Language: | English |
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2022
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| _version_ | 1826316532524777472 |
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| author | Malmir, K |
| author2 | Smith, J |
| author_facet | Smith, J Malmir, K |
| author_sort | Malmir, K |
| collection | OXFORD |
| description | <p>The optical trapping of nanoparticles and biomolecules has recently attracted considerable attention as a means for the manipulation and characterization of target analytes. Nano-particulate pollutants and microbiological organisms, such as viruses, have optical characteristic signatures based on their refractive index, size, and polarizability, as well as spectral signatures. By leveraging these properties, optical sensing and spectroscopy techniques have proven to be powerful tools for detecting and characterizing nanoparticles at the single-particle level. In this work, we show that the confined optical field in a Fabry-Perot style microcavity resonator can be used as a means for both trapping and measuring nanoparticle characteristics with high resolution. This characterization is performed by recording the spectral shift of the mode wavelength when the particles diffuse through the microcavity. The maximum mode displacement provides an accurate measure of the polarizability of each particle. We illustrate an accurate measurement of the distribution of polarizabilities in a solution containing a mixture of 50 nm, 75 nm, and 100 nm polystyrene particles in water. This work also studies the theory behind the behavior of particles in an optofluidic microcavity based on the particle size, the optical power, and throughput of a given instrument. Based on the developed theory, the dynamic characteristics of particle trapping in an optofluidic microcavity are further investigated by simulating a stochastic model of nanoparticle dynamics. Furthermore, this work introduces a new model for analyzing the dynamics of nanoparticles in fluidic systems and studying the optical trapping potential. This model allows to accurately design an optical microfluidic system for trapping the desired range of particles based on the flow rate and the optical power, and subsequently detect nanoparticles with high resolution. We express the trapping rate of nanoparticles as a function of the flow rate, the optical power, and the size of particles. Thus, the technique proposed in this work provides a deep understanding of the optical trapping of nanoparticles in flowing fluid, which is crucial for trapping and manipulating nanoparticles and biomolecules. We also show that similar-sized particles of different materials can be distinguished as a result of the difference in refractive indexes, which means the introduced method is sensitive to the refractive index. Therefore, it can be a powerful method to analyze nanoparticles in a solution in applications where we need high-resolution measurement at the single-particle level.</p> |
| first_indexed | 2024-03-07T07:15:03Z |
| format | Thesis |
| id | oxford-uuid:470eeabd-7f4f-426a-98ed-9122a592158c |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:46:45Z |
| publishDate | 2022 |
| record_format | dspace |
| spelling | oxford-uuid:470eeabd-7f4f-426a-98ed-9122a592158c2024-12-08T09:17:36ZCharacterization of nanoparticles with optical fluidic cavityThesishttp://purl.org/coar/resource_type/c_db06uuid:470eeabd-7f4f-426a-98ed-9122a592158cPhotonicsCavity resonatorsOptofluidicsEnglishHyrax Deposit2022Malmir, KSmith, J<p>The optical trapping of nanoparticles and biomolecules has recently attracted considerable attention as a means for the manipulation and characterization of target analytes. Nano-particulate pollutants and microbiological organisms, such as viruses, have optical characteristic signatures based on their refractive index, size, and polarizability, as well as spectral signatures. By leveraging these properties, optical sensing and spectroscopy techniques have proven to be powerful tools for detecting and characterizing nanoparticles at the single-particle level. In this work, we show that the confined optical field in a Fabry-Perot style microcavity resonator can be used as a means for both trapping and measuring nanoparticle characteristics with high resolution. This characterization is performed by recording the spectral shift of the mode wavelength when the particles diffuse through the microcavity. The maximum mode displacement provides an accurate measure of the polarizability of each particle. We illustrate an accurate measurement of the distribution of polarizabilities in a solution containing a mixture of 50 nm, 75 nm, and 100 nm polystyrene particles in water. This work also studies the theory behind the behavior of particles in an optofluidic microcavity based on the particle size, the optical power, and throughput of a given instrument. Based on the developed theory, the dynamic characteristics of particle trapping in an optofluidic microcavity are further investigated by simulating a stochastic model of nanoparticle dynamics. Furthermore, this work introduces a new model for analyzing the dynamics of nanoparticles in fluidic systems and studying the optical trapping potential. This model allows to accurately design an optical microfluidic system for trapping the desired range of particles based on the flow rate and the optical power, and subsequently detect nanoparticles with high resolution. We express the trapping rate of nanoparticles as a function of the flow rate, the optical power, and the size of particles. Thus, the technique proposed in this work provides a deep understanding of the optical trapping of nanoparticles in flowing fluid, which is crucial for trapping and manipulating nanoparticles and biomolecules. We also show that similar-sized particles of different materials can be distinguished as a result of the difference in refractive indexes, which means the introduced method is sensitive to the refractive index. Therefore, it can be a powerful method to analyze nanoparticles in a solution in applications where we need high-resolution measurement at the single-particle level.</p> |
| spellingShingle | Photonics Cavity resonators Optofluidics Malmir, K Characterization of nanoparticles with optical fluidic cavity |
| title | Characterization of nanoparticles with optical fluidic cavity |
| title_full | Characterization of nanoparticles with optical fluidic cavity |
| title_fullStr | Characterization of nanoparticles with optical fluidic cavity |
| title_full_unstemmed | Characterization of nanoparticles with optical fluidic cavity |
| title_short | Characterization of nanoparticles with optical fluidic cavity |
| title_sort | characterization of nanoparticles with optical fluidic cavity |
| topic | Photonics Cavity resonators Optofluidics |
| work_keys_str_mv | AT malmirk characterizationofnanoparticleswithopticalfluidiccavity |