A screw-actuated pneumatic valve for portable, disposable microfluidics

This work describes a simple and inexpensive approach for controlling the pneumatic valves that were invented in Quake's group to miniaturize the whole system for portable and disposable microfluidic devices. The valves are assembled from two parts. One is the polydimethylsiloxane (PDMS) channels formed by multilayer soft lithography. The other is a polymethylmethacrylate (PMMA) frame with machine screws for pressure control. Turning the screws into the control channel inlet (filled with water and covered with a thin PDMS membrane) actuates the valve by creating pressure in the control channel. This method avoids the bulky and expensive external pressure-control facilities and can be easily integrated into portable and disposable devices.