Microfluidic circuits with tunable flow resistances

Microfluidic devices, due to their conveniently small size and the unique physicochemical behavior of fluids in microscale volumes, have become essential tools in many areas of science and technology. Fluid flow in microchannels, microvalves, and micropumps have many parallels with electrical current through wires, switches, and current sources of microelectronic circuits. The equivalent of a variable resistor, however, is still unavailable. Here the authors present addressable microarrays of deformable elements producing sixteen levels of flow resistance. Using a purely resistive electrical circuit analog, they predict the steady-state output of a three-inlet mixer.