3D Micropatterned Functional Surface Inspired by Salvinia Molesta via Direct Laser Lithography for Air Retention and Drag Reduction

Bioinspired functional surfaces are attracting increasing interest in surface engineering, mostly the field of wettability. The Salvinia-effect is a remarkable example superficial air retention and drag force reduction caused by selective chemical coating (super-hydrophobic wax hydrophilic dead cells) peculiar 3D hierarchical morphological structures. replication Salvinia-like patterns at microscale has always been prevented limitations microfabrication techniques, thus hindering relevant technological applications this dimensional scale. Integrating laser lithography traditional dimensionally downscaled, micropatterned inspired for first time both morphology hairs present on Salvinia Molesta leaves reproduced. effect design different energies (bare hydrophilic, hydrophobic, hydrophilic/hydrophobic coating) wettability modeled investigated. demonstrated to be super-hydrophobic terms apparent static contact angle (up 170°) provide tunable adhesion with roll-off from less than 10° 90°. They successfully proved underwater capability, sustained stable Cassie-Baxter state under external hydrostatic pressure up 4 atm. proposed tested hydrodynamic conditions: 40% energy saved.