Integrated Biosensor Systems: Automated Microfluidic Pathogen Detection Platforms And Microcantilever-Based Monitoring Of Biological Activity
Recent advances in micro- and nanofabrication technology have led to the development of a wide range of integrated biosensor platforms. Though multiple sensors and assays have been developed for the rapid and sensitive detection of cells, proteins, and other small molecules, few systems have successfully integrated sample preparation, sample handing, and detection components onto a single platform. This dissertation has aimed to tackle some of the challenges associated with developing innovative and portable biosensor platforms. In this work, microfluidic modules for fluid handling using electrohydraulic pumps, magnetic bead-based sample preparation protocols, DNA extraction, purification, and real-time amplification detection were individually investigated and ultimately integrated into a single microfluidic chip platform. A LabView®-based instrument was designed to automate the platform, allowing the user to easily interface with the instrument and modify parameters via laptop-controlled software. Although technical challenges still remain for increasing cell capture efficiencies, detection sensitivities, and assay optimization, the platform presented here provides a solution for the portable field-deployable detection of foodborne pathogens with raw-sampleto-result capabilities. In addition to an integrated microfluidic pathogen detection platform, we also developed a cantilever-based biosensing system for the monitoring of changes in biological activity of single cells. We fabricated an array of tipless gold-coated silicon nitride cantilevers with an exposed nitride pad at the tip for chemical functionalization to capture single cells. As part of these investigations, experiments were performed which successfully demonstrated the monitoring changes in the increased activity of bacterial flagella and detection of capture and subsequent immunogenic events in RBL mast cells. Our efforts in developing integrated biosensor systems not only demonstrates improvements in microfluidic devices and cantilever-based sensing technologies, but also provides exciting new avenues toward the development of innovative integrated biosensor systems.
dissertation or thesis