Normally-closed, leak-tight piezoelectric microvalve under ultra-high upstream pressure for integrated micropropulsion

This paper presents a leak-tight piezoelectric microvalve, operating at extremely high upstream pressures for microspacecraft applications. The device is a normally-closed microvalve fabricated mostly by the micromachining of silicon wafers. The microvalve consists of a custom-designed piezoelectric stack actuator bonded onto silicon valve components, such as the seat, boss and tether, in a stainless steel housing. Major seating configurations include narrow edge seating rings and tensile-stressed silicon tethers that contribute to the desired normally-closed leak-tight operation. The microvalve operations have been demonstrated with a ´helium leak detector scale´ leak rate of 10^-4 sccm at 800 psi. Dynamic microvalve operations of up to 1 kHz have been successfully demonstrated at the pressures in the range of 0∼1000 psi. The measured static flow rate of a microvalve with an applied potential of 10 V is 52 sccm at an inlet pressure of 300psi. The measured power consumption, to hold the microvalve seat fully open, is 3 mW with the applied potential of 30 V. The measured dynamic power consumption is 180 mW for 100 Hz continuous operation at 100 psi.