spin rates are known it is possible to create an automated programme to control the
change in spin rate at specific times throughout the process. Figure5.24shows a
sequence of three real images acquired from a disc designed to isolate blood
plasma, meter these samples and distribute them to the periphery of the disc
following the liquid handling protocol defined in Figs.5.10and5.11. Coloured
water is used as the functional liquid for better visualisation. First, the sample
centrifuged at 30 Hz. Once the plasma has been separated the spin rate is increased
to 40 Hz to burst the first DF valve, this releases the plasma to flow into the metering
chambers and the excess to the overflow waste chamber (Fig.5.24b). Finally, the
spin rate is increased again to 50 Hz which bursts the final two DF valves allowing
the metered plasma to reach the prefilled reagent chambers (Fig.5.24c).
8 Conclusion
The Centrifugal Microfluidic platform offers great versatility in the field of bio-
medical diagnostics with applications in environmental monitoring and beyond;
this versatility is due to its ease of use and minimal hardware requirements. In the
best case scenario, a Lab-on-a-Disc can run a diagnostic test with a minimal impute
Fig. 5.24 Disc functionality photographed by the custom spin stand described in Fig.5.7
5 The Centrifugal Microfluidic: Lab-on-a-Disc Platform 141