Mechanically programmed valving technology and the active flow switching application in centrifugal microfluidics

Centrifugal microfluidic system (Lab-on-CD) is attractive for realizing the conventional laboratory processes on a single microfluidic platform. Efficient valving technology for centrifugal microfluidics is highly desired for fluidic sample regulation. This paper reports a new valving technology based on the intrinsic centrifugal force. The valving system is mechanically programed to achieve sequential control of fluidic samples. The performance of the valving system was tested using a microfluidic chip fabricated using 3D printing technology. The valve can be controlled by manipulating the rotational speed and showed good performance. The effect of the system’s physical parameters on the burst frequencies of the valve and the interaction between different valves were investigated both experimentally and theoretically. The burst frequencies of the valves can be tuned easily by changing the physical parameters of the mechanical system. An active flow switch was designed and tested based on sequential control of multiple valves. It is capable of operation at low rotation frequency with no requirement for reversed rotation direction as in other reported work. The valving system is highly reliable, compact, and easy to be fabricated. It works independent of the microfluidic chip, thus could be reversibly used and easily reconfigured for different application on the centrifugal platform.