Femtosecond laser surface texturing of pure zinc for biomedical applications

Femtosecond laser surface texturing is a promising technique to tune the corrosion behavior of biodegradable materials to better match tissue healing rates. Zinc stands out for its biodegradability, moderate corrosion rate, and low corrosion product accumulation, but the effects of laser texturing parameters on its degradation rate have not been fully explored yet. This work investigates femtosecond laser texturing of pure zinc, evaluating the effects of laser intensity, scanning speed, pitch, and number of passes on surface properties and corrosion performance. The ultrashort laser pulses enabled precise surface structuring through localized material removal while limiting the heat affected zone, with an increase in the surface oxygen content of the textured samples. The influence of laser texturing parameters was assessed using a statistically planned approach. All laser variables significantly affected roughness, leading to a regression model with an adjusted-R 2 of 0.99. Higher roughness also enhanced surface hydrophobicity. Laser-treated samples were subjected to immersion tests over 14 days in NaCl solution, which caused significant mass losses and increased solution pH, both strongly dependent on the laser radiant exposure. In general, laser-treated samples exhibited lower mass losses and pH changes than non-treated zinc, which is attributed to the formation of the protective oxide layer generated during laser treatments. The maximum Zn 2+ concentration was reached on the first day and subsequently decreased over time due to the precipitation of corrosion products. These results demonstrate the possibility of tailoring the degradation behavior of zinc surfaces for biomedical applications.