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Proceedings Paper

Applications of shape memory alloys: advantages, disadvantages, and limitations
Author(s): A. David Johnson; Valery Martynov; Vikas Gupta
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Paper Abstract

Titanium-nickel (TiNi) based shape memory alloys (SMAs) are used in a wide range of applications. They are especially practical as thin film actuators because of the large work output per unit of actuator mass and ability for rapid thermal cycling due to large surface to volume ratio. Sputter deposited thin TiNi film has been developed for use in miniature actuators for microvalves, microrelays, optical switches and also for building small implantable medical devices. Chemical composition of the deposited SMA must be held within close limits and for the film to have shape memory properties a crystallization anneal is required. To avoid flaws in film quality the surface on which SMA is deposited has to meet certain criteria. Basic MEMS processes (photolithography and chemical etching) are used for device fabrication. Although TiNi is resistant to most chemicals, some acids used in MEMS can damage it. Thus, selection of processes and reagents compatible with TiNi requires care and experimentation. This paper discusses some applications of SMA thin films along with experience gained in bringing device s to production readiness. It illustrates simple design rules for incorporating shape memory microactuators in MEMS devices and describes some of the pitfalls to be avoided.

Paper Details

Date Published: 28 September 2001
PDF: 11 pages
Proc. SPIE 4557, Micromachining and Microfabrication Process Technology VII, (28 September 2001); doi: 10.1117/12.442964
Show Author Affiliations
A. David Johnson, TiNi Alloy Co. (United States)
Valery Martynov, TiNi Alloy Co. (United States)
Vikas Gupta, TiNi Alloy Co. (United States)

Published in SPIE Proceedings Vol. 4557:
Micromachining and Microfabrication Process Technology VII
Jean Michel Karam; John A. Yasaitis, Editor(s)

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