Contributing Editor, MEMS Investor Journal
Heating, ventilation, air conditioning and refrigeration (HVAC/R) today use bulky solenoid-controlled valves to manage the flow of refrigerants. But Microstaq claims its MEMS based silicon expansion valve (SEV) is smaller and more accurate than both conventional valves including the most advanced pulse motor valves (PMVs) and thermostatic expansion valves (TXVs).
Founded in 2000, Microstaq subsequently licensed its MEMS microvalve technology from TRW and has developed the technique for its SEV technology. The MEMS microvalve itself only controls nanoliters, but is used as a pilot to provide proportional command pressure to a conventional spool valve that can be sized to fit nearly any amount of flow.
The MEMS based Microstaq chip housing its silicon expansion valve (bottom) is much smaller than a conventional solenoid valve.
"We are the only ones developing MEMS silicon microvalves that can be used as a pilot for controlling very large flows," said Rachid Kaina, General Manager of HVAC/R.
The company’s initial application is HVAC/R, but it is also planning to aim for the automotive market too. "We ares initially targeting HVAC/R market, but our next generation devices are targeting automobile transmissions," said Nelson Fuller, Vice President of Research. "We can put six of these microvalves in the same area as two conventional soleniods in an automatic transmission."
Used inside a standard assembly housing, the Microstaq chip serves as the heart of its metering system.
The MEMS micro valve is constructed from two layers of silicon and a third electrically controlled central mechanical layer with integrated resistors that heat up to provide linear motion due to their thermal expansion thereby opening and closing the microfluidic ports on the chip.
The Microstaq MEMS chips permit two-way piloted flow control to be used as an expansion valve in HVAC/R systems.
The company’s MEMS microvalve is currently in production for retrofitting into existing HVAC/R applications, and will be integrated into original equipment manufacturers (OEMs) new models starting next year.
Copyright 2010 MEMS Investor Journal
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