Pumping fluids in microfluidic systems using the elastic deformation of poly(dimethylsiloxane)
This paper demonstrates a methodology for storing and pumping fluids that provide a useful capability for microfluidic devices. It uses microfluidic screw valves to isolate fluids in poly(dimethylsiloxane) (PDMS) microcompartments, in which the pressure of the liquid is stored in the elastic deformation of the walls and ceiling of the compartments. Fluids can be stored under pressure in these structures for months. When the valves are opened, the walls and ceiling push the fluid out of the compartments into microfluidic channels. The system has five useful characteristics: (i) it is made using soft lithographic techniques; (ii) it allows multiple reagents to be preloaded in devices and stored under pressure without any additional user intervention; (iii) it makes it possible to meter out fluids in devices, and to control rates of flow of fluids; (iv) it prevents the user from exposure to potentially toxic reagents; and (v) it is hand-operated and does not require additional equipment or resources.