| A thermal bubble actuated, nozzle-diffuser pumping system is demonstrated by the combination of several innovative micromachined components, including a micro-to-macro fluidic interconnector, a bubble-powered nozzle-diffuser pump, a microfluidic mixer, and a micro gas bubble filter. As part of this research, characterization of the transient thermal bubble formation mechanism in the micro scale is also conducted to assist the design and optimization of the thermal bubble powered microfluidic system.; Polysilicon resisters, 100 x 10 x 0.5 μm3, are fabricated and tested in isopropyl alcohol (IPA) to study the transient bubble formation phenomena. After a bubble is formed, the bubble growth rate is found to be proportional to the square root of time that is similar to the heat diffusion controlled bubble growth mode in the macro scale experiments. The overall transient temperature responses are analyzed by a first-order heat transfer model and verified with experimental results.; A microfabrication process for micro-to-macro fluidic interconnectors is developed for high density fluidic interconnection by using integrated polymer sealant.; A bubble powered micro pump is demonstrated based on the nozzle-diffuser channel design to regulate flow and the nucleation and collapsing of bubbles to create actuation.; The thermal bubble actuated micro pump is integrated with a microfluidic mixer and a gas bubble filter to complete a microfluidic system. Finally, a gas bubble filter is demonstrated by utilizing width of microchannels to create a pressure barrier to separate gas bubbles and pure liquid. Gas bubble of 10μm in diameter or larger are successfully filtered out in experiments.; The research results provide alternative approaches for many issues in microfluidic systems, such as liquid actuation, micro-to-macro fluidic interconnection, microfluidic mixing, and liquid/gas separation. Some future research directions, such as thermal analysis of the micro pump and detail bubble growing/collapsing mechanism, are proposed to mature the developed micro devices. (Abstract shortened by UMI.)... |
