The development of microfluidic devices for environmental and food quality analysis
Date
2012
Authors
Jokerst, Jana Catherine, author
Henry, Charles, advisor
Barisas, George, committee member
Strauss, Steven, committee member
Borch, Thomas, committee member
Tjalkens, Ronald, committee member
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Abstract
Whether termed micro-total analysis systems, lab-on-a-chip, or microfluidic devices, the technologies that define the field of microfluidics have shown great promise for overcoming many challenges in environmental, clinical, and biological analyses. The numerous advantages these devices bring to analysis, such as cost, reduced analysis time, minimal sample and reagent requirements, integration of multiple processing steps in a single device, and the possibility for automation and on-site analysis, make them attractive alternatives to conventional instrumentation. The work comprising this dissertation focuses on novel, miniaturized platforms for both food and water quality analysis. The development of two devices for these applications will be presented: a microchip capillary electrophoresis (MCE) method for the determination of perchlorate in drinking water and a paper-based analytical device (μPAD) for the detection of foodborne, pathogenic bacteria. Recent advances in microfluidics have had a significant focus in environmental analysis. The portability and rapid analysis these devices provide has brought us closer to on-site monitoring of environmental matrices and real-time measurements in these systems. Perchlorate has gained considerable attention over the past decade as a water contaminant. Prolonged consumption of contaminated drinking water has been linked to impaired thyroid function, leading to a number of adverse health effects. Current detection methods rely on expensive bench-top instruments, housed in a centralized laboratory. While these techniques offer high sensitivity and low detection limits, they are costly, time-consuming, and do not provide the ability to monitor perchlorate on-site. This dissertation describes the development of a microchip capillary electrophoresis device capable of rapid analysis of ppb levels of perchlorate in drinking water. Unique separation chemistry in which zwitterionic surfactant micelles are incorporated into the running buffer allows for selective analysis of perchlorate. The device performance was tested via analysis of spiked drinking water samples with detection limits of the system below the U.S. Environmental Protection Agency requirement. Further advancement of the device for analysis of more complex environmental samples is also discussed herein. The remaining chapters present a novel, paper-based device for bacterial detection. Faster, simpler methods of detecting foodborne pathogens are highly desired, particularly in the food industry. Existing methodologies are time-consuming, cumbersome, and require highly trained personnel. Often, several days are required for confirmation of food contamination, and in an industry with time-sensitive products, this delay is a major hindrance. Presented here is a paper-based analytical device (μPAD) developed for more rapid and simple detection of three foodborne pathogens: Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica. The μPAD provides a fast, easy-to-use technology for first-level screening that compliments existing methods. The device comprises a simple spot test on filter paper and utilizes species-specific enzymatic assays for colorimetric bacteria detection. In this work, the device is used to detect the three pathogens in spiked ready-to-eat meat samples. Concentrations as low as 101 cfu/cm2 were detected within an 8-12 h of enrichment. While this first phase of development shows great promise, work is ongoing to enhance assay selectivity and reduce overall analysis time.
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Subject
microfluidics
perchlorate
pathogenic bacteria
paper-based analytical devices