Magnetically controlled flexible valve for flow manipulation in polymer microfluidic devices

The paper describes design and fabrication of simple, magnetically actuated flexible polymer valve for flow manipulation in the microfluidic network. The valve is made up of a polymer composite. The CoFe2O4 was embedded in PDMS (Polydimethylsiloxane) for making this polymer composite. The composites of different volume percentage loading of CoFe2O4 were used and for each concentration valves of different thicknesses were fabricated, as thin rectangular membranes. This membrane was magnetized in the thickness direction and showed typical permanent magnet behaviour. For actuation of the valve the membrane was deflected by externally applied magnetic force which can close either of the channels. The flow manipulation and proper operation of the valve depends on thickness and percentage loading of magnetic material in membrane as well as dimensions of channel, chamber and membrane with respect to the location of outlet channels. The microfluidic channel was completely close for any fluid flow rate.