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Microfluidics Platforms for Quantitative, Multiplexed Protein Detection


Ahmad, Habibullah (2011) Microfluidics Platforms for Quantitative, Multiplexed Protein Detection. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/04A6-YT31.

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This thesis describes the development of microfluidic platforms that enable cheap, facile, rapid, and multi-parameter protein sensing. The first section of this work describes two strategies for high density DNA microarray patterning: microcontact printing and flow patterning. A protocol is provided for micron-scale alignment of multiple PDMS stamps to a single substrate, and a simple strategy to allow very low aspect-ratio stamping is enumerated.

The second section describes the formation of high density antibody microarrays using flow patterned DNA microarrays in conjunction with DEAL chemistry, and applies these microarrays to biological measurements. The platform’s performance is first characterized using a human chorionic gonadotropin assay, and is subsequently used to stratify 22 cancer patients from frozen serum samples by quantifying the levels of twelve serum proteins. A microfluidic plasma separation device is then detailed to allow for similar measurements from fresh finger pricks of blood.

The third section of this work outlines improvements to the flow patterning platform through two alternate schemes: covalent attachment and DMSO patterning. Both protocols are shown to dramatically increase the consistency of microarray elements across a single chip when compared to the initial method. Theoretical simulations are used to describe the mechanism by which DMSO enhances patterning consistency.

The fourth section describes the design and fabrication of a robotics system that is capable of autonomously interfacing and manipulating PDMS substrates, and its application to producing barcode microarrays. The resulting substrates show unprecedented consistency from chip to chip, and we demonstrate through massively parallel single-cell measurements that data derived from different substrates is statistically indistinguishable.

Finally, we introduce an integrated software and hardware package designed to facilitate and automate microfluidic control at the laboratory level. We further provide the technical details of a related system which optimizes and comprehensively automates microfluidic blood assays such that even non-technical users who have never worked with microfluidics can regularly obtain the same standard of data that is produced in the lab.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Microfluidics, Protein Detection, Molecular Patterning, Microcontact Printing, Biosensing, Automation
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemistry
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Heath, James R.
Thesis Committee:
  • Gray, Harry B. (chair)
  • Barton, Jacqueline K.
  • Scherer, Axel
  • Heath, James R.
Defense Date:23 February 2011
Non-Caltech Author Email:habib (AT)
Additional Information:Title varies in 2011 Commencement Program: Microfluidic Platforms for Quantitative, Multiplexed Protein Detection.
Record Number:CaltechTHESIS:06072011-185553467
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6506
Deposited By: Habibullah Ahmad
Deposited On:14 Jun 2011 22:09
Last Modified:09 Oct 2019 17:11

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PDF (PhD Thesis) - Final Version
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