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Proceedings Paper

Shape memory micromechanisms for microvalve applications
Author(s): Manfred Kohl; Matthias Popp; Berthold Krevet
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Paper Abstract

Two micromechanisms including a microactuator of a shape memory alloy (SMA) and a retaining system are presented, which are implemented in a microvalve to maintain a closed condition while no power is supplied. In one design, the retaining system is realized by a pseudoelastic SMA microspring coupled to the SMA microactuator. Alternatively, a pressure compensation mechanism is developed based on two mechanically coupled membranes, which are located above and below the SMA microactuator. The mechanical, electrical and thermal behaviors of the SMA microactuator are simulated by a coupled finite element program. Based on force-displacement characteristics of microspring and microactuator, a design of the two micromechanisms is developed. The investigation reveals several advantages of the pressure-compensation mechanism. In particular, pressure compensation allows a maximum controllable pressure difference of more than 500 kPa compared to 100 kPa for the microspring mechanism. Furthermore, a larger actuation stroke close to the maximum possible design value is achieved. Dynamic flow measurements reveal similar time constants for both mechanisms of 15 and 55 ms for opening and closing, respectively.

Paper Details

Date Published: 21 July 2004
PDF: 12 pages
Proc. SPIE 5387, Smart Structures and Materials 2004: Active Materials: Behavior and Mechanics, (21 July 2004); doi: 10.1117/12.539490
Show Author Affiliations
Manfred Kohl, Forschungszentrum Karlsruhe (Germany)
Matthias Popp, Forschungszentrum Karlsruhe (Germany)
Berthold Krevet, Forschungszentrum Karlsruhe (Germany)

Published in SPIE Proceedings Vol. 5387:
Smart Structures and Materials 2004: Active Materials: Behavior and Mechanics
Dimitris C. Lagoudas, Editor(s)

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