| The goal of this study is to develop novel microfabrication methods and microfluidic devices for BioMEMS applications. The emphasis is on the development of new hot embossing techniques, the design of microfluidic functions and biocompatible packaging methods for polymeric microfluidic chips.;First, two unconventional hot embossing techniques were developed: laser assisted and sacrificial template based hot embossing. In laser assisted embossing, localized micro patterning can be achieved on polymer surfaces with a cycle time of less than 1 minute due to the localized heating, which is comparable with that of micro injection molding. The sacrificial template based hot embossing solved the de-molding issue involved in conventional hot embossing especially for high aspect ratio microstructures. Embossing of microstructures with aspect ratio of 6 was demonstrated successfully and the possibility of laser assisted embossing in conjunction with sacrificial template embossing was investigated.;A fishbone microvalve was designed based on the concept of super-hydrophobicity such that the valve function remains after protein blocking, a required step in some enzyme-linked immuno-sorbent assays (ELISA) applications to prevent non-specific binding. Compared with another type of super-hydrophobic microvalve developed based on the micro-/nano structure formation by chemical synthesis, the fishbone valve can be easily incorporated into the microfluidic designs. Polymer compact-disk (CD) microfluidic platform integrated with different fluidic features was designed and fabricated. We have demonstrated successfully that flow sequencing can be achieved on a CD-like microfluidic platform.;For packaging microfluidic platforms, a new interstitial bonding technique has been developed, which bonds the polymer-based microfluidic platforms without introducing any alien materials in to microchannels. This method can easily bond biochips with complex flow patterns, but in a relatively smaller size. A multi-channel DNA sequencing chip was demonstrated experimentally. Another bonding method, CO2 assisted bonding, was also demonstrated for bonding a 5-inch CD platform. By applying a thin PLGA interlayer, the CD platform can be bonded at low temperature and low pressure to achieve a hermetic bonding. ELISA tests showed that both bonding methods have no or little effect on the activity of preloaded proteins, which is essential for microfluidic designs that requires preloading of some regents such as proteins, antibody/antigen and cells. |
