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Title:Portable optical microscopic systems for nanoparticle detection
Author(s):Liu, Leyang
Contributor(s):Cunningham, Brian
Degree:B.S. (bachelor's)
Subject(s):photonic crystals
interferometric scattering microscopy
Abstract:Optical imaging of individual nanoparticles (NPs) has gained significant attention in recent years because of its important application in fields such as biosensing. However, traditional optical microscopes’ capabilities of observing materials less than 100 nanometers are limited due to limited signal-to-noise ratio. In this thesis, we designed and built two microscopic systems incorporated with photonic crystals (PCs) that can capture the image of NPs of 100 nanometers and less in diameter. With a budget of under 7000 dollars each, the systems occupy approximately one-tenth the space of their full-size predecessors and are convenient to be transported between laboratories. The first system is photonic resonator absorption microscopy (PRAM), which matches the surface plasmonresonant wavelength of the nano-urchins (NUs) to the resonant wavelength of the PCs. The reflected light intensity is significantly decreased at this wavelength, forming a type of microscopy that we can use for biosensing. The other system is photonic resonator interferometric scattering microscopy (PRISM), in which the scattered light of nano-spheres (NSs) on PCs interferes with the reflected reference light to create an intensity contrast. The PCs amplify the scattered light through resonant near-field enhancement and improves the collection efficiency of the scattered photons by gathering them into the in-plane guided modes. These benefits enable us to image NPs smaller than those of the PRAM system, reaching the 40-nanometer regime. The fabrication and characterization of PC will also be discussed in this thesis.
Issue Date:2021-05
Genre:Dissertation / Thesis
Date Available in IDEALS:2021-08-11

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