P. J. S. Buenconsejo, H. Y. Kim, S. Miyazaki, University of Tsukuba, Tsukuba, Japan
Recent trends in surgery toward less-invasive surgical procedures require biomedical microdevices, such as stents, catheters and guidewires. Superelastic Ti-Ni microtubes are attractive for these practical applications, but the size of commercially available Ti-Ni microtubes is limited to bigger than 250 μm in inner diameter. In this study, a novel method was utilized to fabricate Ti-Ni microtubes by sputter-deposition on a Cu-wire of 50 μm diameter. During sputter-deposition, the Cu-wire was rotated at 15rpm in order to completely cover the Cu-wire with Ti-Ni. After deposition, Cu was removed by etching to produce a tube hole. SEM observation of the cross-section showed a uniform wall thickness of 6 μm and an inner diameter of 50 μm. The composition of the microtubes was determined to be Ti-52at.%Ni by EPMA. As-deposited microtubes were amorphous and they were crystallized at 873K for 3.6ks. The shape memory effect was confirmed by thermal cycling under various constant stresses using a tensile machine. The Ms at zero applied stress was estimated to be 170K. Stable superelastic behavior of Ti-Ni microtube was confirmed by tensile tests at room temperature, therefore microtubes fabricated by this novel method are attractive for practical applications.
Summary: Recent trends in surgery toward less-invasive surgical procedures require biomedical microdevices, such as stents, catheters and guidewires. Superelastic Ti-Ni microtubes are attractive for these practical applications, but the size of commercially available Ti-Ni microtubes is limited to bigger than 250 μm in inner diameter. In this study, a novel method was utilized to fabricate Ti-Ni microtubes by sputter-deposition on a Cu-wire of 50 μm diameter. The microstructure, shape memory behavior and mechanical properties were investigated.
