Shape-Setting of Self-Expanding Nickel-Titanium Laser-Cut and Wire-Braided Stents to Introduce a Helical Ridge

Area of Science:

• Biomaterials Engineering
• Medical Device Manufacturing
• Cardiovascular Interventions

Background:

• Altered hemodynamics from endovascular devices can impact peripheral stenting success.
• Flow-enhanced stent designs aim to restore physiological blood flow and reduce complications.
• Manufacturing flow-enhanced Nickel-Titanium (Ni-Ti) stents requires specialized processes due to Ni-Ti's complex behavior.

Purpose of the Study:

• To develop and refine a manufacturing method for inducing a helical ridge on Ni-Ti self-expanding stents.
• To investigate the effects of shape-setting parameters on stent mechanical performance, material properties, and surface finish.
• To establish a feasible heat treatment regime for helical shape-setting in laser-cut and wire-braided Ni-Ti stents.

Main Methods:

• Developed a manufacturing process involving custom fixtures for helical shaping, followed by air furnace heat treatment and cold water quenching.
• Systematically explored heat treatment parameters (e.g., 500°C/30min) for shape-setting.
• Assessed mechanical properties, material transformation temperatures (Af), and surface finishing via microscopy.

Main Results:

• Successfully imparted a helical ridge onto both laser-cut and wire-braided Ni-Ti stents.
• Identified optimal heat treatment parameters (500°C/30min) yielding suitable transformation temperatures (Af=23.5°C) and comparable mechanical properties.
• Confirmed no adverse effects on surface finishing and successful deliverability testing with full recovery of helical configuration.

Conclusions:

• Demonstrated the feasibility of an additional heat treatment process for helical shape-setting of Ni-Ti stents.
• This method can be applied to laser-cut and wire-braided devices for advanced stent designs.
• The developed technique supports the creation of flow-enhanced stents to improve peripheral stenting outcomes.