Applications of Liquid Repellent Surfaces and Patterned Wettability for Microfluidics and LC-MS
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Authors
Salomons, Timothy
Date
Type
thesis
Language
eng
Keyword
Microfluidics , LC-MS , Fractionation , Superhydrophobic surfaces , Slippery Liquid Infused Porous Surfaces
Alternative Title
Abstract
Microfluidic devices make heavy use of liquid repellent surfaces in a variety of different manners. Digital microfluidics uses liquid repellent surfaces to ensure that sample droplets do not inadvertently adhere to the device and that analyte is not lost to adsorption. Superhydrophobic surfaces are a popular choice for such a purpose but are unable to repel organic solvents due to their low surface tension. This thesis explores the potential of the omniphobic Slippery Liquid Infused Porous Surface (SLIPS) as a replacement for superhydrophobic surfaces in digital microfluidics. A SLIPS was incorporated into a magnetically actuated digital microfluidic device, and the parameters for successful actuation of droplets on the device were thoroughly investigated. In addition, a series of demonstrative applications were conducted with the device. Two liquid-liquid extractions were performed using the SLIPS-based device. The first: a simple extraction of an organic dye to determine its partition coefficient (logP). The second: a more complex extraction of natural products from the media of a bacterial culture, followed by mass spectral analysis to confirm the successful extraction of natural products. In addition, the synthesis of nylon 6,6 was performed on the device, with successful synthesis verified with mass spectrometry. Our experiments demonstrated the ability to perform synthetic reactions as well as chemical analysis using digital microfluidic devices equipped with omniphobic surfaces.
Liquid repellent surfaces are also used in sessile droplet microfluidics, where they are used to generate regions of patterned wettability and surface energy traps (SETs). This thesis explored a potential application of patterned wettability, in the design and construction of a micro-fractionation device for LC-MS. The high density of the SET array allows for a much greater number of micro-fractions to be stored than in a well-plate or tray of vials. The micro-fractions can then be stored or transported before being analyzed via the liquid micro-junction surface sampling probe (LMJ-SSP). We found that target shaped SETs 2.5mm in diameter spaced 1mm apart were ideal for a flow rate of 500μL/min, although the optimal SET parameters are expected to increase and decrease in accordance with the LC flow rate. A model separation of caffeine and phenacetin was archived using the micro-fractionator, with individual fractions each spanning 0.36s of separation time. Mass spectral analysis of the archived separation was performed using the LMJ-SSP, and the chromatogram reconstructed from mass spectral data over 24 hours after the separation was performed. The success of this experiment demonstrated the ability to store LC separations on a chip and analyze them at a later date, which allows LC-MS experiments to be performed asynchronously, providing increased flexibility in analytical chemistry workflows.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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Copying and Preserving Your Thesis
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.