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

Today, the focus in microfluidic platforms for diagnostics is on the integration of several analysis steps toward sample-to-answer systems. One of the main challenges to integration is the requirement for serial valving to allow the sequential release of fluids in a temporally and spatially controlled manner. The advantages offered by centrifugal microfluidic platforms make them excellent candidates for integration of biological analysis steps, yet they are limited by the lack of robust serial valving technologies. This is especially true for the majority of centrifugal microfluidic devices that rely on hydrophilic surfaces, where few passive serial valving techniques function reliably. Building on the useful functionality of centrifugal microfluidic siphoning previously shown, a novel serial siphon valve is introduced that relies on multiple, inline siphons to provide for a better controlled, sequential release of fluids. The introduction of this novel concept is followed by an analytical analysis of the device.Proof-of-concept is also demonstrated, and examples are provided to illustrate the range of functionality of the serial siphon valve. The serial siphon is shown to be robust and reproducible, with variability caused by the dependence on contact angle, rotation velocity, and fluidic properties (viz., surface tension) significantly reduced compared to current microfluidic, centrifugal serial valving technologies.

The applications of microfluidic technologies in medical diagnostics continue to increase, particularly in the field of nucleic acid diagnostics. While much attention has been focused on the development of nucleic acid amplification and detection platforms, sample preparation is often taken for granted or ignored all together. Specifically, little or no consideration is paid to the development of microfluidic systems that efficiently extract nucleic acids from biological samples. Here, a centrifugal microfluidic platform for mechanical sample lysis and homogenization is presented. The system performs sample lysis through a magnetically actuated bead-beating system followed by a centrifugal clarification step. The supernatant is then transferred for extraction using a unique siphon. Several other new microfluidic functions are implemented on this centrifugal platform as well, including sample distribution, a unique hydraulic capillary valve, and self-venting. Additionally, the improved system has features with a small footprint designed specifically for integration with further downstream processing steps. Biological validation of the platform is performed using Bacillus subtilis spores and clinical samples (nasopharyngeal aspirates) for respiratory virus detection. The platform was found to be as efficient as in-tube bead-beating lysis and homogenization for nucleic acid extraction, and capable of processing 4 samples in batch to near PCR-ready products in under 6 min.

Over the past two decades, centrifugal microfluidic systems have successfully demonstrated their capability for robust, high-performance liquid handling to enable modular, multi-purpose lab-on-a-chip platforms for a wide range of life-science applications. Beyond the handling of homogeneous liquids, the unique, rotationally controlled centrifugal actuation has proven to be specifically advantageous for performing cell and particle handling and assays. In this review we discuss technologies to implement two important steps for cell handling, namely separation and capturing/counting.

There has been a recent surge of research output on magnetophoretic lab-on-a-chip systems due to their prospective use in a range of applications in the life sciences and clinical diagnostics. Manifold applications for batchmode or continuous-flow magnetophoretic separations of cells, proteins, and nucleic acids are found in bioanalytics, cell biology, and clinical diagnostics. To ensure stable hydrodynamic conditions and thus reproducible separation, state-of-the-art magnetophoretic lab-on-a-chip systems have been based on pressure-driven flow (Gijs in Microfluid