Microstructure-induced Petal Effect on Hierarchical Ceramic Surfaces Fabricated by Multi-step Imprinting

This study demonstrates the bio-inspired petal effect—high water adhesion with superhydrophobicity—on sintered alumina surfaces fabricated via multi-step imprinting. A hierarchical surface of 50 μm macro-waves and 2 μm micro-lines exhibited this effect. Notably, 2 μm single-scale patterns showed lower contact angles than flat surfaces, contradicting conventional geometric models. We attribute this anomaly to “microstructure-induced pinning”, where the increased exposure of grain boundaries creates localized hydrophilic defects in the hydrophobic coating. This highlights the impact of geometric structures and micro-defects on wettability, providing a crucial foundation for developing durable functional surfaces.