Scanning Super-resolution Imaging in Microfluidic Environment Using Microsphere Super-lens and Optically-induced Dielectrophoresis

Abstract

This thesis reports on the realization of near-field scanning super-resolution imaging in microfluidic environment through combining opto-electrokinetic (OEK) micro-manipulation system with microsphere super-lens microscopy. OEK systems are versatile platforms for micro-and nano-scale manipulation, separation, immobilization, patterning of single entity or mass entities. On the other hand, microsphere super-lens microscopy is a recent near-field imaging technique that can reach down to 50nm resolution without requiring high-precision probes, complex super-lens or fluorescence.

A section of the thesis presents efforts on constructing and improving the OEK micro-manipulation platform.A review of the theories in electro-kinetic forces, in particularly dielectrophoretic force, is presented. High level of interactivity has been demonstrated in the platform, making it possible for remote and real-time micro-manipulation through a mobile phone application. Moreover, the OEK system offers a wide array of toolbox, such as the ability to crosslink different types of polymers, pattern gold nanoparticles and deposit organic salts. A thorough study of the quantification of the dielectrophoretic force is also being documented, providing a basis for the scanning motion of the microsphere lens in a microfluidic environment for super-resolution imaging.

Another section of this thesis describes approaches to further advance the microsphere super-lens microscopy:including collecting and extracting more information through image processing and vertical scanning, removing the background noise through spatial filtering and inclined illumination, discovering new imaging modes, and expanding the theory and mechanism of super-resolution by microspheres. A particular attention is given to the new discovery of “real-imaging” mode for microsphere super-lens, which can offer flexibility and compatibility to various objective lenses.

Finally, this thesis also demonstrates the potential of combining these two systems. It is the demonstration of the first non-cantilever-based solution to realize scanning near-field super-resolution imaging inside a confined microfluidic environment.

Date of Award	9 Nov 2016
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Wen Jung LI (Supervisor)