Near Net-Shape Fabrication of Superelastic NiTi Devices by Sputtering and Photoetching

NiTi-films were fabricated by DC magnetron sputtering from cast-melted disc targets. The obtained freestanding films revealed superelastic properties in tensile testing experiments. At 37°C superelastic properties were achieved showing a closed-loop hysteresis and a plateau of more than 5% strain. Photolithography and wet etching technology were applied in order to fabricate net-shaped devices. Achievable structure sizes range in the order of the NiTi film thickness, i.e. typically between 5 and 15 (mu)m. Tensile testing experiments reveal a remarkable strain tolerance of these devices which summed up to a superelastic strain of up to 5%. It has been demonstrated that the deposition process can be transferred to the fabrication of NiTi tubes, which have high potential for application as vascular implants, e.g. stents.