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Micropatterned Freestanding Superelastic TiNi Films

Authors

  • Rodrigo Lima de Miranda,

    1. Faculty of Engineering, Chair for Inorganic Functional Materials, Institute for Materials Science, University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany
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  • Christiane Zamponi,

    1. Faculty of Engineering, Chair for Inorganic Functional Materials, Institute for Materials Science, University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany
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  • Eckhard Quandt

    Corresponding author
    1. Faculty of Engineering, Chair for Inorganic Functional Materials, Institute for Materials Science, University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany
    • Faculty of Engineering, Chair for Inorganic Functional Materials, Institute for Materials Science, University of Kiel, Kaiserstr. 2, 24143 Kiel, Germany
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  • Funding by the German Research Foundation (DFG) via the Collaborative Research Center SFB 459 and financial support of the Deutsche Forschungsgemeinschaft within the project QU 146/11-1 is gratefully acknowledged.

Abstract

Micropatterned freestanding superelastic TiNi films in the thickness range between 20 and 100 µm are attractive materials for medical in vivo applications. Micropatterning of these materials by UV lithography and etching is a challenging task, as wet etching has severe design limitations due to its isotropic nature while dry etching shows much to low etching rates. This study presents a method to fabricate freestanding TiNi films (with thicknesses higher than 20 µm) with a minimum feature size 5 µm based on UV lithography, sacrificial layer and wet etching technology. This method was successfully applied to the fabrication of TiNi films with 50 µm thickness and 25 µm feature size. These superelastic films showed remarkable tensile strengths up to 1100 MPa and elongations upon fracture of more than 40%.

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