- Medical Applications of Sputter-Deposited Shape Memory Alloy Thin Films

Shape memory alloys are able to provide high work output when due to the martensitic transformation. Therefore, they are a promising candidate for actuation mechanisms in microsystems, e.g. in microvalves. Sputter deposited SMA thin films are already in use as free-standing films or as composites. Since it is also possible to deposit and structure the SMA composites on Si substrates by photolithographic techniques, the fabrication process is compatible to MEMS and therefore most favorable for an number of applications. Superelastic shape memory materials are of special interest in medical applications due to the large strains at constant stress and their biocompatibility. Superelastic NiTi thin films have been fabricated by magnetron sputtering using cast melted targets. Special heat treatment was performed to adjust superelastic properties and transformation temperatures. A superelastic strain of up to 6.5% at 37°C was obtained. Although NiTi shows an excellent biocompatibility enhanced antibacterial properties would significantly broaden its application range. Coatings containing Ag have already been used for this application. In order to apply this approach to TiNi-based alloys thin films of different TiNiAg compositions have been prepared by sputtering.

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Some factors affecting the properties of sputter deposited NiTi-based shape memory alloy thin films

10.1117/12.468642 ◽

2002 ◽

Cited By ~ 7

Author(s):

Xu Huang ◽

Yong Liu

Keyword(s):

Thin Films ◽

Shape Memory Alloy ◽

Shape Memory ◽

Factors Affecting ◽

Sputter Deposited

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Sputter-Deposited Shape-Memory Alloy Thin Films: Properties and Applications

MRS Bulletin ◽

10.1557/mrs2002.46 ◽

2002 ◽

Vol 27 (2) ◽

pp. 111-114 ◽

Cited By ~ 86

Author(s):

Akira Ishida ◽

Valery Martynov

Keyword(s):

Thin Film ◽

Thin Films ◽

Shape Memory Alloy ◽

Shape Memory ◽

Microelectromechanical Systems ◽

Sputter Deposition ◽

Bulk Materials ◽

Shape Memory Actuators ◽

Sputter Deposited ◽

Memory Characteristics

AbstractShape-memory alloy (SMA) thin films formed by sputter deposition have attracted considerable attention in the last decade. Current intensive research demonstrates that unique fine microstructures are responsible for the superior shape-memory characteristics observed in thin films as compared with bulk materials. Simultaneously, much effort has been undertaken to develop and fabricate micro devices actuated by SMA thin films. This article reviews the research to date on shape-memory behavior and the mechanical properties of SMA thin films in connection with their peculiar microstructures. Promising applications such as microvalves are demonstrated, along with a focused discussion on process-related problems. All of the results indicate that thin-film shape-memory actuators are ready to contribute to the development of microelectromechanical systems.

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