A Hybrid Three-Way Valve for Gas Chromatography Systems

This paper reports a three-way valve that combines a lithographically microfabricated silicon substrate and valve seats with prefabricated piezoelectric actuators and polyimide valve membranes. The microvalve is designed for low dead volume and flow channel chemical resistance, as needed for gas chromatography systems. In contrast with valves that use microfabricated valve membranes, the incorporation of prefabricated membranes significantly simplifies manufacturing and improves the structural robustness. Further, this three-way valve provides independent open-close control for each flow path, rather than simply switching the flow from one path to the other, which is the case for most three-way valves. The overall footprint of the device is 3x3x1.5 cm(3). Each flow path of the three-way valve provides an open-state flow conductance of 4.42 sccm/kPa, a leakage flow conductance of 0.0012 sccm/kPa, and an overall open-close ratio of 3.68x10(3). In preliminary tests, the valve had been switched 1900 times over 24 hours without showing any performance variation.