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Titanium-Nickel Shape Memory Thin Film Actuators for Micromachined Valves

Published online by Cambridge University Press:  15 February 2011

H. Kahn ,
W. L. Benard ,
M. A. Huff  and
A. H. Heuer
H. Kahn
Affiliation:
Department of Materials Science and Engineering
W. L. Benard
Affiliation:
Department of Electrical Engineering and Applied Physics, Case Western Reserve University, Cleveland, Ohio 44106
M. A. Huff
Affiliation:
Department of Electrical Engineering and Applied Physics, Case Western Reserve University, Cleveland, Ohio 44106
A. H. Heuer
Affiliation:
Department of Materials Science and Engineering
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Abstract

Microelectromechanical valves have been fabricated from silicon wafers using standard bulk micromachining techniques, which utilize thin (2 μm) films of sputter-deposited titaniumnickel as the actuators. The TiNi shape memory alloy actuators are thermally driven by resistive heating, through the passage of an electric current. TiNi diaphragms (8.4 mm wide) are fabricated and tested in a pressure-temperature controlled fixture in order to determine the mechanical properties of the shape memory film. If a silicon island is left attached to the center of the diaphragm, this can act as a “boss” whose movement against an orifice will open and close the valve. The orifice can be etched into a second silicon wafer or machined from another rigid material. Use of mechanical spacers and external bias springs result in a normally-closed or normally-open configuration. Modulations of up to 90 percent have been observed in gas flows of up to 0.6 liter/min. Water flows as high as 5 ml/min. have been modulated by 60 percent.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 444: Symposium I – Materials for Mechanical and Optical Microsystems , 1996 , 227
Copyright
Copyright © Materials Research Society 1997

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