PDMS membrane with integrated open-porous foam featuring a gradient in pore-size for simultaneous filtration and pumping of fluids in microfluidic structures

In this contribution we present a concept for simultaneous filtration and pumping solely realized with a single polymer based membrane. An open-porous foam with a gradient in pore size, which essentially resembles a nozzle-diffuser structure, is integrated into the center of a flexible PDMS (Polydimethylsiloxane) membrane, which is placed into a small fluid cavity with symmetric inlet and outlet geometry. The actuation of the membrane is achieved with an electromagnetic coil from the outside and a small magnetic ring, which has also been integrated into the membrane. The sinusoidal excitation of the membrane leads to a vibrational movement of the membrane in the fluid cavity, and due to the asymmetry in pore size of the integrated foam a unidirectional fluid flow evolves in the system. Thus, the proposed device can be used for simultaneous pumping and filtration with the additional advantage of reduced sensitivity to fouling.