Unravelling the mystery of fish scales in lowering ice adhesion

The influence of static surface properties, such as free energy, toughness, and elasticity, on icephobicity has been extensively studied and documented in existing literature. However, there remains limited understanding of the role played by surface dynamic characteristics in facilitating ice removal. This study investigates the ice adhesion strength of authentic Arctic salmon (Salmon salar) skin, revealing intriguing anisotropic ice adhesion behavior. Results indicate a significant decrease in ice adhesion strength (141 ± 47 kPa) when sheared against the growth orientation of fish scales compared with shearing along this orientation (353 ± 95 kPa). The distinctive structural evolution of fish scales during shearing can lead to a sequential rupture process, thereby diminishing ice adhesion. Additionally, the study highlights the significance of the opening and peeling capacity of fish scales in controlling ice detachment, defined as the ability of unit scales to separate from their underlying structures and adhesives under applied force. Enhancing this capacity could further reduce ice adhesion strength (66 ± 15 kPa), facilitating effortless ice detachment on fish scales. The mechanical robustness of fish scales offers new possibilities for designing hard and durable anti-icing surfaces.