doi:10.1038/nindia.2013.158 Published online 26 November 2013
Researchers have fabricated a silicon microregulator from silicon wafers and an actuator. This microregulator can be used to control the flow of gases and liquids, and is promising for use as a microvalve in satellite propulsion based on ion thrusters .
Conventional valves for controlling gas and liquid flow normally employ a magnetic component, as it enables them to rapidly generate large forces and deflections. Most such valves are applied to control the flow of either gases or liquids — but not both. There is dearth of studies describing valves for controlling the flows of both gases and liquids.
To develop such a versatile valve, the researchers fabricated the silicon microregulator from two silicon wafers. The bottom wafer housed the inlet and outlet channels, whereas the top wafer acted as a valve. The top and bottom wafers were bonded together at their peripheries by gold bond. A piezoelectric actuator was attached to the top of the device using adhesive.
The researchers used helium and nitrogen gases and water to test the efficacy of the microregulator in controlling gas and liquid flow. The flow rate through the valve was measured for inlet pressures ranging from 1 bar to 6 bar and for voltages between 0 volts and 160 volts.
The flow rate through the microregulator increased with increasing voltage as well as with increasing pressure; of these two parameters, the voltage had the greatest effect on the flow rate. At 160 volts and 6 bar, helium had a higher flow rate than nitrogen. The flow rate of water under the same conditions was considerably lower than those of nitrogen and helium. The microregulator can be used to accurately control the volume of water.
The valve in the microregulator was found to be leak tight for operating pressures up to 5 bar. It is suitable for the development of microsatellites — a new trend in space research.