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Dual-elastomer tip arrays are developed as a simple and cost-effective approach to significantly improve the uniformity and precision of polymer pen lithography (PPL). Both experiment and mechanical simulation demonstrate that the hard-apex, soft-base tip structure of the dual-elastomer tip array leads to precise control of feature size and reduced variation among different tips over large areas through fine control of the tip deformation. The dual-elastomer tip array is believed to be readily applied to fabricate nano- and microstructures for fundamental study and applications such as bioassays, sensors, optical and electronic devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

This thesis describes a novel microfluidic platform to control the macromolecular concentrations and their applications in constructing the phase diagram of polymer aqueous solutions and in the high-throughput screening of protein crystallization conditions at the nanoliter scale. The microfluidic platform was fabricated using the soft-lithography method and based on poly(dimethylsiloxane) (PDMS) material, which is widely used in microfluidic device. PDMS is gas and water permeable elastomer. By exploiting the permeability of the gas and water in PDMS, we developed the degassed-PDMS nanoliter liquid dispensing system, the controlled microevaporation method in constructing the phase diagram of polymer aqueous solution, and the screening platform of protein crystallization conditions., This thesis describes two types of degassed-PDMS nanoliter liquid dispensing system. One is dispensing without the microvalve, in which various liquids are dispensed through the degassed PDMS microchannel. It involves two steps: in the first step, the PDMS microchannel patch (or the entire microchip) is placed in a vacuum chamber for a certain time; in the second step, the target liquid is deposited at the inlet of the PDMS channel and dispensed into the PDMS microchamber. The other method is dispensing with the aid of PDMS microvalve. This method combines the valve control and degassed PDMS pumping source, which provides more control over on the liquid dispensing, such as isolating, mixing, etc., Zhou, Xuechang., Adviser: Bo Zheng., Source: Dissertation Abstracts International, Volume: 72-04, Section: B, page: ., Thesis (Ph.D.)--Chinese University of Hong Kong, 2010., Includes bibliographical references (leaves 53-56)., Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web., Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web., also in Chinese., isbn: 9781124494142, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Zhou, Xuechang., Thesis (M.Phil.)--Chinese University of Hong Kong, 2007., Includes bibliographical references (leaves 51-53)., s in English and Chinese., p.i, 摘要 --- p.ii, Acknowledgement --- p.iii, Table of contents --- p.iv, Chapter 1 --- Introduction --- p.1, Chapter 1.1 --- Protein crystallization --- p.1, Chapter 1.1.1 --- The principle of protein crystallization --- p.3, Chapter 1.1.2 --- Protein crystallization approaches --- p.4, Chapter 1.1.3 --- Screening strategies and approaches --- p.6, Chapter 1.2 --- Microfluidic systems for protein crystallization --- p.7, Chapter 1.2.1 --- Integrated valve-controlled microfluidic system --- p.8, Chapter 1.2.2 --- Droplet-based microfluidic system --- p.9, Chapter 1.2.3 --- Objective of the research --- p.10, Chapter 2 --- Nanoliter Liquid Dispensing Method --- p.12, Chapter 2.1 --- Introduction --- p.12, Chapter 2.2 --- Experimental --- p.14, Chapter 2.2.1 --- The fabrication of SU-8 master --- p.14, Chapter 2.2.2 --- The fabrication of PDMS microfluidic device --- p.16, Chapter 2.2.3 --- The fabrication of glass and PMMA microwells --- p.17, Chapter 2.2.4 --- The liquid dispensing into microwells --- p.17, Chapter 2.3 --- Results and discussions --- p.20, Chapter 2.3.1 --- The internal vacuum pumping source --- p.20, Chapter 2.3.2 --- The efficiency of the pumping --- p.23, Chapter 2.3.3 --- The removal of PDMS channel patch --- p.26, Chapter 2.4 --- Conclusion --- p.29, Chapter 3 --- The Screening of Protein Crystallization Conditions --- p.30, Chapter 3.1 --- Introduction --- p.30, Chapter 3.2 --- Experimental --- p.31, Chapter 3.2.1 --- The design and fabrication of the screening chip --- p.31, Chapter 3.2.2 --- The screening of protein crystallization conditions --- p.32, Chapter 3.2.3 --- Crystallization and X-ray diffraction of an unknown protein --- p.33, Chapter 3.3 --- Results and discussions --- p.33, Chapter 3.3.1 --- Sparse matrix screening strategy in microwell arrays --- p.33, Chapter 3.3.2 --- The results of the sparse matrix screening --- p.39, Chapter 3.3.3 --- Crystal extraction and X-ray diffraction --- p.40, Chapter 3.4 --- Conclusion --- p.41, Chapter 4 --- Conclusion --- p.43, Chapter 4.1 --- Summary --- p.43, Chapter 4.2 --- Discussions and future directions --- p.44, Appendix Information --- p.47, References --- p.51, http://library.cuhk.edu.hk/record=b5893176, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)