This thesis presents the development of a refractometric sensor based on
quantum dot-embedded polystyrene microspheres. The technique uses optical
resonances within a microsphere, known as Whispering-Gallery Modes (WGMs), which
produce narrow spectral peaks. The basic theory of WGMs is reviewed and specifically
discussed for biosensing application.
The spectral shifts of WGM peaks are sensitive to changes in the local refractive
index. In the experiments, two-photon excited luminescence from the quantum dots
couples into several WGMs within the microresonator. By optimizing the detection area,
the spectral visibility of the WGMs is improved. The spectral shifts are measured as the
surrounding index of refraction changes. The experimental sensitivity is about five times
greater than that predicted by Mie theory.
The sensor element is based on commercially available dielectric microspheres
with a diameter about 10 μm. Thus, the technique is more economic and suitable for
sensing applications, compared to microspheres of 100 μm in size which can only be
made in the laboratory.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/85998 |
| Date | 10 October 2008 |
| Creators | Pang, Shuo |
| Contributors | Meissner, Kenith E. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, born digital |
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