Type of Document	Dissertation
Author	Shao, Guocheng
Author's Email Address	gshao1@tigers.lsu.edu, opt_sgc@hotmail.com
URN	etd-03242011-201607
Title	Polymer Based Microfabrication and Its Applications in Optical MEMS and BioMEMS
Degree	Doctor of Philosophy (Ph.D.)
Department	Engineering Science (Interdepartmental Program)
Advisory Committee	Advisor Name Title Wang, Wanjun Committee Chair Charalampopoulos, Tryfon T. Committee Member Choi, Jin-Woo Committee Member Soper, Steven A. Committee Member Hynes, Robert I. Dean's Representative
Keywords	microchip immunoassay microlens microfluidic cytometer thick su-8
Date of Defense	2010-11-22
Availability	unrestricted
Abstract Due to its ease of fabrication, low cost and great variety of functionalities, polymer has become an important material in microfabrication. MEMS devices with polymer as the structure material have found applications in various fields, especially in BioMEMS and optical MEMS. In this dissertation, three polymer based microfabricated devices/components have been developed and tested. Various polymer based fabrication techniques, such as high aspect ratio SU-8 photolithography, three dimensional polydimethylsiloxane (PDMS) soft lithography, multi-layer soft lithography and PDMS double casting technique have been developed/studied and employed in the device fabrication process. The main contribution of this dissertation includes: (1) Developed two novel methods for the fabrication of out-of-plane microlens. The PDMS and UV curable polymer (NOA73) replication technique made possible the fast replication of out-of-plane microlens and broaden the lens material selection. The in-situ pneumatical microlens fabrication technique, on the other hand, provides feasible method to integrate out-of-plane microlens into microfluidic chips requiring minimal design footprint and fabrication complexity. (2) Design, fabrication and test of a microchip flow cytometer with 3-D hydrofocusing chamber and integrated out-of-plane microlens as on-chip optical detection component. The developed micro flow cytometer offers 3-D hydrofocusing like conventional cytometer cuvette, and has on-chip microlens for optical signal collection to improve the detection efficiency. With the latest design improvement, the hydrofocusing chamber can focus the sample stream down to less than 10 m in diameter in both vertical and horizontal directions. (3) Development of a PDMS microchip based platform for multiplex immunoassay applications. Integrated micro valves were employed for manipulation of fluidic reagents in the microchannel network. PDMS surface was used as the solid phase substrate for immuno-reactions. Preliminary results showed that, even with low cost polyclonal goat anti-mouse IgG as the reporter antibody, the detection limit of goat mouse IgG can reach as low as 5 ng/mL (about 33 pM). With the continuous advance in microfabrcation technique and polymer science, polymer based microfabrication and polymer MEMS devices will keep to evolve. In the future, more work needs to be done in this field with great potential and endless innovations.
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