Thermally regulated valve for minute flows

In this work, a gas valve using a microstructured silicon valve lid and a stainless steel valve seat clamped axially together in an aluminum cylinder is investigated. The difference in coefficient of thermal expansion of these components makes the valve open and close on a temperature change. A simple model accounting for elastic deformation of the system’s components is proposed to facilitate design of the valve. By means of a helium leak detector, a typical increase in flow rate from 1.0×10−8to1.0×10−4sccs gaseous helium under a pressure of up to 10bars was observed upon the increase of temperature from 12 to around 98°C, after a single breaking-in. Plastic deformation of the valve seat as a consequence of an imprint of the microstructured valve lid and contaminating particles was studied. Microscopy confirmed a tolerance for particles of up to a few micrometers in diameter. Larger particles were found to be a possible cause of failure.