Gas microvalves
We design, fabricate and evaluate low-footprint microvalves for large gas flow control. The research includes optimisation of flow nozzle and valve actuator design.
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Micropneumatic devices are microfabricated components that are used to control the pressure and/or flow characteristics of a fluid. Commercially available microvalves are expensive and focus on niche markets where typically component size reduction outweighs cost increase, or where semiconductor valve materials can withstand harsh gas environments. The microvalve industry can be successful outside the specific niche markets it currently focuses on if the cost-per-performance can be reduced to a level in the range of conventional components. The research in this field at the Department of Signals, Sensors and Systems focuses therefore on component cost reduction through miniaturisation.
One research effort introduced the optimal nozzle shape for the most common type of gas microvalves: seat microvalves [1,2]. The analysis of the nozzle geometry of this type of valves showed that an optimal nozzle design consists of a large amount of ultraminiaturised parallel orifices rather than one single orifice structure. This design allows controlling larger gas flow while minimising the required actuator stroke.
In another study, a novel micromachined knife gate valve, the X-Valve, was introduced [3]. This component is designed as the hart of so-called IP-converter or EP-converter, which convert an electronic signal (current I or voltage E) into a pneumatic signal (pressure P). The novel IP-converter concept contains a set of two X-Valves that control the pneumatic connection between a supply pressure port, a work pressure port and a vent port. Demonstrator X-Valve structures were fabricated and measurements confirm that the novel design allows for controlling gas flows of at least one order of magnitude above today’s microdevices. The design and construction of a completely microfabricated micromachined IP-converter is on-going.
The figure shows a schematic view of a micromachined IP-converter containing two knife gate valves, X-valves. For each X-Valve flow and valve actuation are perpendicular to one another, hence the X-Valve name. The valve actuators thus do not counteract the pneumatic force they control and can be made small in size, resulting in smaller overall device dimensions.
Project sponsor
- Vinnova (Swedish Agency for Innovation Systems) through the SUMMIT competence centre
