A pneumatically-actuated three-way microvalve fabricated with polydimethylsiloxane using the membrane transfer technique

In this paper, a three-way microvalve system composed of three independent one-way valve units is presented; Each valve unit has a membrane, which is actuated by external negative air pressure. Intervals between the valve units are smaller than 780 mu m, which opens up the possibility of realizing a high-density microvalve array. The small intervals were realized by providing the system with a layer of microchannels to conduct the air pressure to the valve units. In spite of the extra layer of microchannels, the device has been fabricated through a simple process by adopting polydimethylsiloxane (PDMS) as the material for the microchannel chips as well as the membrane. In particular, a newly developed technique for wafer level transfer of a PDMS membrane has been proven to be effective. Flow characteristics of the microvalve system for water are presented. The microvalve works in an on-off manner with hysteresis. No leakage has been observed in the closed state. In the open state, measured flow resistances (pressure drops) are within the range of 1.65-2.29 kPa (mu l min(-1))(-1), and consistent with an electric circuit model.