Leak-tight piezoelectric microvalve for high-pressure gas micropropulsion

This paper describes the results of our development of a leak-tight piezoelectric microvalve, operating at extremely high upstream pressures for microspacecraft applications. The device is a normally closed microvalve assembled and fabricated primarily from micromachined silicon wafers. The microvalve consists of a custom-designed piezoelectric stack actuator bonded onto silicon valve components (such as the seat, boss, and tether) with the entire assembly contained within a stainless steel housing. The valve seat configurations include narrow-edge seating rings and tensile-stressed silicon tethers that enable the desired, normally closed, leak-tight operation. Leak testing of the microvalve was conducted using a helium leak detector and showed leak rates of 5 x 10(-3) sccm at 800 psi (5.516 MPa). Dynamic microvalve operation (switching rates of up to 1 kHz) was successfully demonstrated for inlet pressures in the range of 0 similar to 1000 psi. The measured static flow rate for the microvalve under an applied potential of 10 V was 52 seem at an inlet pressure of 300 psi. The measured power consumption, in the fully open state, was 3 mW at an applied potential of 30 V. The measured dynamic power consumption was 180 mW for 100 Hz continuous operation at 100 psi.