Rapid Formation and Testing of Self-expanding NiTi Frames with a Small Form Factor Suitable for Minimally Invasive Implants

NiTiNOL (commonly referred to as nitinol or NiTi) wires feature exceptional shape memory and super-elastic characteristics, while shape-setting is often a costly process. Among the steps in this process, heat treatment requires exposure to high temperatures for shape-setting. Traditionally, metal fixtures are used for this purpose. However, their manufacturing costs can be significant, which is unideal for iterating prototypes. This work demonstrates a recently introduced approach using sacrificial fixtures made of copper tubes, which eliminates the need for expensive fixtures. These copper tubes allow for the formation of complex geometries, and they offer a scaffold for various phases of the fabrication process. Moreover, ammonium persulfate is used for selective copper etching, which simplifies the production of NiTi frames. This work's findings confirm the effectiveness of this technique and demonstrate the successful shape-setting of NiTi wires for self-expanding frames. This methodology paves the way for future research, allowing for rapid prototyping of NiTi wireframes for various applications, especially those in medical devices.