Integrating Biosensors for Air Monitoring and Breath-Based Diagnostics

Abstract: The air we breathe is the concern of all of us but nevertheless we only know very little about airborne particles, and especially which biological microorganisms they contain. Today, we live in densely populated societies with a growing number of people, making us particularly vulnerable to air transmission of pathogens. With the recent appearance of highly pathogenic types of avian influenza in southeast Asia and the seasonal outbreaks of gastroenteritis caused by the extremely contagious norovirus, the need for portable, sensitive and rapid instruments for on-site detection and monitoring of airborne pathogens is apparent.Unfortunately, the integration incompatibility between state-of-the-art air sampling techniques and laboratory based analysis methods makes instruments for in-the-field rapid detection of airborne particles an unresolved challenge.This thesis aims at addressing this challenge by the development of novel manufacturing, integration and sampling techniques to enable the use of label-free biosensors for rapid and sensitive analysis of airborne particles at the point-of-care or in the field.The first part of the thesis introduces a novel reaction injection molding technique for the fabrication of high quality microfluidic cartridges. In addition, electrically controlled liquid aspiration and dispensing is presented, based on the use of a thermally actuated polymer composite integrated with microfluidic cartridges.The second part of the thesis demonstrates three different approaches of biosensor integration with microfluidic cartridges, with a focus on simplifying the design and integration to enable disposable use of the cartridges.The third part to the thesis presents a novel air sampling technique based on electrophoretic transport of airborne particles directly to microfluidic cartridges. This technique is enabled by the development of a novel microstructured component for integrated air-liquid interfacing. In addition, a method for liquid sample mixing with magnetic microbeads prior to downstream biosensing is demonstrated.In the fourth part of the thesis, three different applications for airborne particle biosensing are introduced and preliminary experimental results are presented.