Microfluidic platforms for thermal convection-based manipulation and microcasting system

概要

This thesis describes the applications of particle manipulation based on thermal convection in microfluidics and a microfluidic system based on microcasting technology in biological field. Microfluidics refers to the science and methods that control, manipulate, process, and analyze small amounts of fluids. This technique is revolutionizing the traditional methods and equipment with the great advantages of the miniaturization ability, saving time, space, reagent, and cost, together with accelerating reaction rate and enhancing the sensitivity. The main proposal of this thesis is to explore this new manipulation method by thermal convection in microfluidics, develop integrated microfluidic and microcasting systems, and show the new opportunities in the biological field. Therefore, this research is both of an exploratory nature and practical application. In the initial part of this research, I investigate thermal convection in a static fluid and develop a contactless manipulation platform based on thermal convection. The platform combines microheaters and an area cooling system to precisely steer sedimentary particles or cells through thermal convection. Results of a cell viability test confirmed the method's biocompatibility. In the second part, I explore thermal convection in a continuous fluid and present an integrated microfluidic system based on thermal convection to realize 2D/3D manipulation. By increasing the temperature of the microheater, the direction of particle motion changes from the horizontal direction to the vertical direction. Based on the principle, a polydimethylsiloxane (PDMS) microchannel with multi-outlets in different height is developed to demonstrate the application for 2D/3D manipulation. Third, I develop a microcasting system in microfluidics for cell patterning. The microcasting system is based on a degassed PDMS microchannel without any pumps to control the flow. Through experiments and simulations, the pressure change, geometry parameters, and viscosity effect are clarified. Long-time cell patterning is archived by using the cross-linked albumin as the casting material for cell culture. Overall, I develop the microfluidic platform based on thermal convection for particles/cells manipulation and microcasting system for cell culture, which extends the way of manipulation in microfluidics and showcases successful application in biological process.