Multi-functional Centrifugal Microfluidic Discs for Rio-detection Applications

This work is motivated by the need of miniaturized and automated biomedical assay platforms in the field of point-of-care applications. The focus of microfluidic system for integrated biomedical assays has attracted more and more attention in recent years. Centrifugal microfluidics, or lab-on-a-disc (LOAD), is believed to be an excellent candidate to tackle complex biomedical analysis problems with a broad range of validated functional units such as valving, mixing and metering. However, it is still at early stage. While many individual biological analysis steps, functions, and systems have been demonstrated, there are relatively few examples of real LOAD. New developments targeting true sample-to-answer devices for biomedical assays will lead to wide-spread utilization of centrifugal microfluidic technologies as a valuable tool in the near future. The goal of this study is on the emphasis of new technical achievements towards establishing advanced centrifugal microfluidic disc-based analysis devices for various biomedical applications.;In this thesis, we have demonstrated a simple yet convenient disc to perform bead-based immunoassays. The disc embeds a series of passive valves and a beads damming structure onto a downscale network. Without beads pre-packaging for specific assays and expensive liquid dispensing system, a broad range of bead based immunoassays can be conducted flexibly on the disc in a rapid and low-cost manner. The integrated platform contains all the necessary functional elements thus allow one-step parallel assays through a frequency protocol. To prove our concept, quantitative analysis of ovalbumin of various concentrations was performed on the device. The integrated device only requires the addition of samples and a single run of device with a precise acceleration speed (3 rpm/s) to trigger a cascade of events that is controlled by the increasing speed, and it takes 5 min 33 s for the solutions to move entirely from the loading pads to the waste chamber followed by the detection. The beads (45 mum - 160 mum) with detection antibody are washed and then aggregated to the small targeted detection region with a small damming microchannel (40 mum) which allows free passage of small molecules while retaining the beads. Our work demonstrates the feasibility of using centrifugation as a possible automated immunoassay system in the future.