Micropatterned Freestanding Superelastic TiNi Films

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%.

Effect of crystallographic compatibility and grain size on the functional fatigue of sputtered TiNiCuCo thin films

“…Further information on the structuring process can be found in [24,27]. The as deposited amorphous samples with a thickness of 18 µm have been homogenized and crystallized in a sequential annealing step using a rapid thermal annealing device.…”

Thin NiTi Films Deposited on Graphene Substrates

“…These microstructural effects in terms of grain orientation and size in thin NiTi films have not been reported before. Typically, the use of Si substrates in combination with thin Cu interlayers results in randomly oriented grains with no fiber texture of the topmost NiTi layer [1,4,8]. Obviously, our microstructural observations must be directly related to the novel combination of graphene and the Cu interlayer.…”

“…To fully implement these novel ideas, it will be necessary to not only provide the composite materials but also to produce the materials in large dimensions and/or in forms like functional foils. Usually free-standing NiTi films are produced by wet-chemical processing [4]. The production of free-standing films without the need of complex chemical processes is another substantial challenge.…”

In Vitro Corrosion Assessment of Additively Manufactured Porous NiTi Structures for Bone Fixation Applications

“…Recently, Nickel-titanium (NiTi) alloys, also known as Nitinol, have become attractive for various applications due to their unique characteristics, such as their shape memory behavior and superelasticity, which allows them to recover from large strains as high as 8% [1][2][3][4]. In addition, NiTi alloys are more biocompatible when implanted inside the human body, and have a more desirable strength and modulus of elasticity compared to the metallic alloys conventionally used (e.g., Ti-6Al-4V) [5][6][7][8].…”