A strongly hydrophobic and serum-repelling surface composed of CrN films deposited on laser-patterned microstructures that was optimized with an orthogonal experiment

Abstract

Owing to frequent contact with blood, the external working medium easily adheres to medical devices such as scalpels and stents, which possibly reduces their performance. To solve this problem and with inspiration from the superhydrophobic and self-cleaning properties of natural lotus leaves, a novel surface composed of laser-patterned (LP) microstructures, with chromium nitride (CrN) films deposited on top, was fabricated on 316 L stainless steel by combining laser patterning and magnetron sputtering. A self-designed circular pattern array was used to generate the LP microstructures. Then, the effects of five key processing parameters, such as the diameter of the circular pattern, spacing of the circular pattern, laser fluence, laser scanning velocity and number of scans, on the wettability of the LP/CrN surface were evaluated using an L16 (45) orthogonal experiment, after which the surface was optimized to further enhance hydrophobicity and serum repellence. The optimized surface strongly corresponded with the Cassie-Baxter model and demonstrated a water (serum) contact angle of 147.7 ± 1.1° (144.2 ± 0.8°) and roll-off angle of 10.8 ± 1.7° (17.1 ± 3.1°), thus showing strongly hydrophobic and serum-repelling characteristics. Moreover, the optimized surface had a weak coffee-stain effect after 60 min of evaporation and exhibited remarkable corrosion resistance in a 3.5 wt% NaCl solution via a potentiodynamic polarization method. This study provides useful insight into the fabrication of a hydrophobic and serum-repelling surface, which can be used to address the problem of blood-adhesion on medical devices.