Chen Zhang

ORCID Identifier(s)

0000-0002-6136-4882

Graduation Semester and Year

2022

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Electrical Engineering

Department

Electrical Engineering

First Advisor

Yuze Sun

Abstract

ABSTRACT: Optofluidic droplet lasers have been developed for different applications in biomedical sciences, such as biosensing, cell tracking, tissue imaging, on-chip spectroscopy, and flow cytometry. Utilizing different generation methods, droplet lasers can be categorized as either static droplet lasers or droplet lasers on the flow. Static droplet lasers, which are supported by a surface or levitated by an external force, can be optically probed for an extended period of time, and thus enabling continuous monitoring of the lasing emission. However, static droplet lasers suffer from low-throughput generation, large size distribution, and poor reproducibility. In contrast, droplet lasers on the flow can be generated in high-throughput by microfluidic devices to yield monodispersed droplets with well-controlled and tunable cavity size. However, because of the flowing nature, the droplet lasers have very limited interaction time with a probe light which makes continuous monitoring of lasing emissions challenge. My research focuses on developing a universal high-throughput microfluidic platform that can generate optofluidic droplet lasers with various structures and optical functions. The platform is based on microfluidic flow-focusing on glass capillaries. A subsequent UV curing unit can be integrated on the platform by demand to cure droplets into microbeads or microcapsules. In this dissertation, we first described the development and characterization of the droplet laser generation platform, in which both single emulsion droplets and double emulsion droplets were reported. Then we demonstrated the development of polymerized single emulsion droplet lasers that were robust, size-tunable, and can be conveniently collected, transferred, and stored for later use after generation. The lasing microbeads used for refractive index sensing were demonstrated to show their prospect in biosensing. Next, we studied the microfluidic platform for double emulsion droplets generation with different material combinations to achieve various optical microresonators. The curing of double emulsion droplets was studied for achieving a low-threshold microcapsule laser. Last, we demonstrated the versatility of this microfluidic platform by developing droplet lasers with ionic liquids. The conclusion and future research directions were presented in the last chapter.

Keywords

Whispering gallery modes, Lasers, Optofluidics, Microfluidics, Flow-focusing platforms

Disciplines

Electrical and Computer Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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