Actuator materials for extreme environments

• Published in: 2005 International Conference on MEMS,NANO and Smart Systems p. 459
• Main Authors: Alberta, E.F., Jiang, X., Rehrig, P., Hackenberger, W.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 2005
• Subjects: Ceramics; Cryogenics; Force control; Optical materials; Piezoelectric actuators; Shape control; Space missions; Telescopes; Temperature distribution; Venus
• ISBN: 0769523986; 9780769523989
• DOI: 10.1109/ICMENS.2005.2

There is a growing need for actuator materials that can operate efficiently at extreme temperatures. For example: the James Webb Space Telescope (JWST) requires shape and position control actuators that operate near 30 K (-243/spl deg/C); while NASA's planned Venus mission requires actuators that operate at 460/spl deg/C (733 K). This paper discusses novel piezoelectric single crystal actuators and ultrasonic motors have been developed for use in cryogenic environments as low as 20 K (-253/spl deg/C) and new ceramic piezoelectrics that operate at temperatures as high as 500/spl deg/C (773 K). Various single crystal piezoelectric actuators have been developed including stack actuators and flextensional actuators with strokes up to 250 /spl mu/m and resolutions of >1 nm at temperatures between 20 K and 300 K. A wobbling mode cryomotor has also developed with a stroke of 1 to 10 mm and a resolution of 20 nm in the temperature range of 77 K to 300 K. The cryogenic actuators presented in this paper feature high precision displacement control, high force output, quick response, low power consumption, and are free of magnetic field interference. These cryogenic actuators are very promising for shape control, precision positioning and force control in various NASA, military and civilian applications such as cryogenic adaptive optics for space telescopes, interferometers in terrestrial planet finder missions, and spectrometers for remote sensing applications. New actuator materials have also been developed specifically for high-temperature applications. This paper addresses development of this material for an ultrasonic rock drilling-coring-abrading tool to quickly sample Venus surface material for chemical analysis. The key innovation behind this device is a BiScO/sub 3/-PbTiO/sub 3/ based piezoelectric ceramic that has been modified to have high resistivity up to 500/spl deg/C. This material was found to have very good piezoelectric properties to the depoling temperature of 420/spl deg/C, and at 450/spl deg/C it functioned as an electrostrictor with an induced piezoelectric coefficient of /spl sim/450 pC/N under a 7 kV/cm DC bias.