A piezoelectric microvalve for cryogenic applications

Abstract

This paper reports on a normally open piezoelectrically actuated microvalve for high flow modulation at cryogenic temperatures. One application envisioned is to control the flow of a cryogen for distributed cooling with a high degree of temperature stability and a small thermal gradient. The valve consists of a micromachined die fabricated from a silicon-on-insulator wafer, a glass wafer, a commercially available piezoelectric stack actuator and Macor TM ceramic encapsulation that has overall dimensions of 1 × 1 × 1 cm 3. A perimeter augmentation scheme for the valve seat has been implemented to provide high flow modulation. In tests performed at room temperature the flow was modulated from 980 mL min −1 with the valve fully open (0 V), to 0 mL min −1 with a 60 V actuation voltage, at an inlet gauge pressure of 55 kPa. This range is orders of magnitude higher flow than the modulation capability of similarly sized piezoelectric microvalves. At the cryogenic temperature of 80 K, the valve successfully modulated gas flow from 350 mL min −1 down to 20 mL min −1 with an inlet pressure of 104 kPa higher than the atmosphere. The operation of this valve has been validated at elevated temperatures as well, up to 380 K. The valve has a response time of less than 1 ms and has operational bandwidth up to 820 kHz.

A Microvalve With Integrated Sensors and Customizable Normal State for Low-Temperature Operation

“…The fabrication process is a variant of the process previously used to create flexure suspended microvalves [20]. Steps have been added to the process to create the embedded sensors, and other steps have been altered to increase yield and decrease process complexity.…”

“…For this paper, piezoelectric actuation is used, to allow proportional flow control, to generate high force, and to minimize the power consumption. Piezoelectric microvalves without integrated sensors have been developed for space applications [18], [19] and in our previous work, they have been shown to work in a cryogenic environment [20].…”

A low-power high-flow shape memory alloy wire gas microvalve

“…The SMA-wire-actuated microvalve also offers the lowest power consumption with respect to existing high-flow microvalves, and is only outperformed by PZT microvalves, which however provide an order of magnitude lower flow rate per footprint. The SMA wire actuator valve has more than one order of magnitude lower power consumption than the gate valves with in-plane actuation [9,10] and has two [4] 6 .3 × 6.6 0% 0.8 W n/a n/a Park et al (seat valve, PZT) [5] 1 orders of magnitude lower voltage than the PZT microvalve [5]. The main drawback of the SMA wire valve compared to the other valves is the high relative leakage.…”

A feasibility study on using inkjet technology, micropumps, and MEMs as fuel injectors for bipropellant rocket engines

“…Only basic calculations have been performed to assess its performance-the in depth analysis and refinement of this design will be the subject of future work. The use of cryogenic propellants has not been taken into account since few data exist relative to the capability of PZT to work at cryogenic temperatures even though work by Park et al [24] has demonstrated a PZT actuated microvalve that operates down to 40 K.…”