Effect of laser polishing on the surface roughness and corrosion resistance of Nitinol stents

In this paper, we investigated the effect of laser polishing at different treatment times on the surface roughness and corrosion resistance of a biliary nickel-titanium (NiTi or Nitinol) stent. A specific area of the stent wire surface was checked for changes in roughness by scanning electron microscopy (SEM) and a noncontact profilometer. The corrosion resistance was assessed by potentiodynamic polarization test and electrochemical impedance spectroscopy. The surface characterization revealed that laser polishing reduced the surface roughness of stent by 34-64% compared to that of the as-received stent surface condition depending on the treatment time (i.e., 700-1600 μm). Measurements using potentiodynamic polarization in simulated body fluid solution showed better anti-corrosion performance of laser-polished stent compared to magnetically-polished stent and has comparable corrosion resistance with the as-received stent condition. In this paper, we have shown a preliminary study on the potential of laser polishing for the improvement of surface roughness of stent without affecting much its corrosion resistance.