A gas chromatography assembly has a substrate wafer with grooves and a valve seat etched therein. A plate cooperates with the wafer and the grooves to define gas channels: a carrier gas channel and a sample gas channel, each passing through the valve seat. A valve actuator is attached to the valve seat...http://www.google.com.tw/patents/US4474889?utm_source=gb-gplus-share專利 US4474889 - Miniature gas chromatograph apparatus
