The development of a rapid, miniaturized, and efficient on-chip sample preparation for "real" sample analysis remains a major bottleneck for the realization of a lab-on-a-chip approach in point-of-care diagnostics. We developed a fully integrated and automated labon-a-disc using centrifugal microfluidics to provide a "sample-in and answer-out" type of biochemical analysis solution with simple, size-reduced, and cost-efficient instrumentation.1 Here, I present various examples of the fully integrated "lab-on-a-disc" developed for broad applications ranging from medical diagnostics to food, environment, and energy applications (Fig. 1A). Active valves on a spinning discWe pioneered the concept of laser-irradiated ferrowax microvalves (LIFM) with colleagues at Samsung Advanced Institute of Technology (SAIT), which provided a simple and robust tool for obtaining fluidic control on a spinning disc.2 The key achievement of this work was the rapid and wireless actuation of multiple valves by simple laser irradiation on nanoheaters, which are 10-nm-sized ferro-oxide nanoparticles dispersed in paraffin wax (Fig. 1B).2 The response time of both the normally open and normally closed valves was very short, and the actuation of the valves was independent of the sequence of the spin speed, sample type, or material properties of the substrates. More recently, we

A portable, disc-based, and fully automated enzyme-linked immuno-sorbent assay (ELISA) system is developed to test infectious diseases from whole blood. The innovative laser irradiated ferrowax microvalves and centrifugal microfluidics were utilized for the full integration of microbead-based suspension ELISA assays on a disc starting from whole blood. The concentrations of the antigen and the antibody of Hepatitis B virus (HBV), HBsAg and Anti-HBs respectively, were measured using the lab-on-a-disc (LOD). All the necessary reagents are preloaded on the disc and the total process of the plasma separation, incubation with target specific antigen or antibody coated microbeads, multiple steps of washing, enzyme reaction with substrates, and the absorbance detection could be finished within 30 minutes. Compared to the conventional ELISA, the operation time was dramatically reduced from over 2 hours to less than 30 minutes while the limit of detection was kept similar; e.g. the limit of detection of Anti-HBs tests were 8.6 mIU mL(-1) and 10 mIU mL(-1) for the disc-based and the conventional ELISA respectively.

We report a fully integrated device that can perform both multiple biochemical analysis and sandwich type immunoassay simultaneously on a disc. The whole blood is applied directly to the disposable "lab-on-a-disc" containing different kinds of freeze-dried reagents for the blood chemistry analysis as well as reagents required for the immunoassay. The concentrations of different kinds of analytes are reported within 22 min by simply inserting a disc to a portable device. Using the innovative laser irradiated ferrowax microvalves together with the centrifugal microfluidics, the total process of plasma separation, metering, mixing, incubation, washing, and detection is fully automated. The analyzer is equipped with an optical detection module to measure absorbances at 10 different wavelengths to accommodate the various kinds of reaction protocols. Compared to the conventional blood analysis done in clinical laboratories, it is advantageous for point-of-care applications because it requires a smaller amount of blood (350 μL vs. 3 mL), takes less time (22 min vs. several days), does not require specially trained operators or expensive instruments to run biochemical analysis and immunoassay separately.

No abstract

No abstract