A normally closed PDMS (polydimethylsiloxane) microvalve

This paper describes a newly developed, normally closed microvalve composed of a molded polydimethylsiloxane (PDMS) microchannel (width 140 µm x height 25 µm) and a spin-coated PDMS membrane (350 µm square), which is deflected by external negative air pressure. By adopting replica molding technique and deep reactive ion etching (DRIE), the fabrication process has been largely simplified in comparison with previously reported microvalves. Load-deflection data of the membrane and flow characteristics of the microvalve are presented. The microvalve works in an on-off style with hysteresis. No leakage has been observed in the closed state.