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Type of Document	Dissertation
Author	Vyawahare, Saurabh
Author's Email Address	saurabhv AT caltech.edu
URN	etd-05252006-223101
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-05252006-223101
Title	Manipulating fluids : advances in micro-fluidics, opto-fluidics and fluidic self-assembly
Degree	PhD
Option	Engineering and Applied Science
Advisory Committee	Advisor Name Title Axel Scherer Committee Chair Marc William Bockrath Committee Member Michael Elowitz Committee Member Scott E. Fraser Committee Member
Keywords	FRET cascade quantum dot barcode elastomeric micro-fluidics solvent resistant micro-fluidics surface plasmon capillary flows
Date of Defense	2006-05-16
Availability	mixed
Abstract This dissertation describes work in three inter-related areas – micro-fluidics, opto-fluidics and fluidic self-assembly. Micro-fluidics has gotten a boost in recent years with the development of multilayered elastomeric devices made of poly (dimethylsiloxane) (PDMS), allowing active elements like valves and pumps. However, while PDMS has many advantages, it is not resistant to organic solvents. New materials and/or new designs are needed for solvent resistance. I describe how novel fluorinated elastomers can replace PDMS when combined with three dimensional (3-D) solid printing. I also show how another 3-D fabrication method, multilayer photo-lithography, allows for fabrication of devices integrating filters. In general, 3-D fabrications allow new kinds of micro-fluidic devices to be made that would be impossible to emulate with two dimensional chips. In opto-fluidics, I describe a number of experiments with quantum dots both inside and outside chips. Inside chips, I manipulate quantum dots using hydrodynamic focusing to pattern fine lines, like a barcode. Outside chips, I describe our attempts to create quantum dot composites with micro-spheres. I also show how evaporated gold films and chemical passivation can then be used to enhance the emission of quantum dots. Finally, within fluids, self-assembly is an attractive way to manipulate materials, and I provide two examples: first, a DNA-based energy transfer molecule that relies on quantum mechanics and self-assembles inside fluids. This kind of molecular photonics mimics parts of the photosynthetic apparatus of plants and bacteria. The second example of self-assembly in fluids describes a new phenomena - the surface tension mediated self assembly of particles like quantum dots and micro-spheres into fine lines. This self assembly by capillary flows can be combined with photo-lithography, and is expected to find use in future nano- and micro-fabrication schemes. In conclusion, advances in fluidics, integrating materials like quantum dots and solvent resistant elastomers along with 3-D fabrication and methods of self assembly, provide a new set of tools that significantly expand our control over fluids.
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