Improved design of low-pressure fluidic microvalves

Multilayer soft lithography (MSL) is used to fabricate monolithic elastomeric on-off microvalves by adopting a two-layer cross-channel architecture. The performance of microvalves is strongly dependent on the two-channel geometry (width, height and shape) and on the thickness of the interlayer membrane. Using a finite element model previously validated against experiments, we propose a new fluidic microvalve design, based on the concept of chemically swelling the thin interlayer membrane so as to induce two stable equilibrium configurations. The complete closure of the new valve may then be achieved by applying a much reduced actuation pressure, down to 1/4 of the pressure needed by the standard monostable design. The maximum stress in the interlayer membrane of the bistable valve also drops to 1/3 of the value corresponding to the standard design. (Some figures in this article are in colour only in the electronic version)