Optimizing femtosecond laser fabricating strategy of Nitinol hypotube for vascular interventional surgery

Abstract

Guidewires and catheters are essential in minimally invasive procedures, particularly in accessing targets within the vascular system for neuron surgery. Femtosecond lasers can precisely cut nickel-titanium micro tubes, known as Nitinol hypotubes, serving as the heads of micro guidewires while protecting their core tips. The quality and geometry of these hypotubes depend on the focus of the laser cutting system. We evaluated the cutting efficiency and quality of Nitinol hypotubes using objective lenses with three numerical apertures (NA). Quantitative analysis indicated that higher NA objectives yield better surface quality, resulting in lower debris. Additionally, cutting with high NA objectives produced significantly lower arithmetic mean surface roughness and enhanced mechanical properties. Using a two-temperature model, we simulated the interaction between femtosecond lasers and Nitinol, showing that higher NA objectives increase electron temperatures, thus improving material removal efficiency. This study also tested the optimized Nitinol hypotube prformance in simulations of invasive neuron surgery.