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Abstract

The consumption of alcohol during breastfeeding can lead to ethanol-contaminated breastmilk, and when consumed by infants, can cause reduced intake of milk and improper development. Health organizations provide oversimplified and vague guidelines to breastfeeding women regarding alcohol consumption. Commercialized products exist to enumerate the presence of ethanol in breastmilk but are underdeveloped. Laboratory separation and detection methods offer accurate and sensitive results, but require off-site testing, expensive equipment, and skilled personnel. This thesis addresses the lack of point-of-care sensors to detect ethanol in breastmilk by developing a microfluidic sensor that uses capacitively coupled contactless conductivity detection and micellar electrokinetic chromatography to separate and detect ethanol in bovine skim milk as a preliminary step towards detecting ethanol in breastmilk. A custom-built capacitively coupled contactless conductivity microfluidic sensor is developed and the effects of shielding techniques and electrode spacing against the signal-to-noise ratio are optimized. The optimal results are achieved with a ground line shielding technique and 500 μm electrode spacing. For ethanol separation, micellar electrokinetic chromatography, a mode of microchip capillary electrophoresis, is employed with a 20 mM citrate, 30 mM sodium dodecyl sulfate, and 4.3% 0.1 M sodium hydroxide (v/v) background electrolyte solution. Ethanol is detected in three Canadian milk brands in five minutes average and a limit of detection of 0.97% (v/v) is achieved. The developed microfluidic sensor serves as a promising approach to the on-site testing of ethanol in breastmilk using laboratory grade separation and detection methods on a miniaturized scale.