Membrane-based valves and inward-pumping system for centrifugal microfluidic platforms

This paper presents an innovative valving and inward pumping technology for elastic polymer based centrifugal microfluidic platform actuated using a specially designed flyball governor. The multilayer microfluidic disc was fabricated using polydimethylsiloxane (PDMS) replica molding process with soft lithography technique. The operational principle is based on the interaction between the elastic PDMS membrane and the actuators (including spring plungers and pins) installed on the flyball governor system. The flyball governor was used as the transducer to convert the rotary motion into a reciprocating linear motion for control of the valve. In addition, the valve's burst frequency can be tuned by changing the pre-load settings of the mechanical system and the valve can be used for multiple valving operations. The experimental results show that the burst frequency of the valve with the same geometry design can range from 900 rpm to 1600 rpm. An inward pump consisting of a membrane valve and a compression chamber was also designed, fabricated, and tested. The pumping cycle can be repeated to obtain a nearly 100% pump efficiency for one cycle. The technology reported in this paper has the potentials to enable a wide variety of operation sequences needed in biological, chemical and medical applications in Lab-on-CD systems.