Leaf beetles inspire novel water-resistant surface using concave structures

By mimicking the structure of a leaf beetle, researchers have developed a superhydrophobic surface resistant to water droplet impact and pressure. This technology is anticipated to enhance efficiency and reduce maintenance costs across various industries, including marine, aviation, and energy. The results are published in Advanced Materials.

Led by Professor Dong Woog Lee in the School of Energy and Chemical Engineering at UNIST, the research team has drawn inspiration from a concave pillar (CP) structure, which is found in the pulvilli of some leaf beetle species and the soil-dwelling springtail (collembola) species. Based on this natural architecture, the team has implemented CP surfaces that can maintain superhydrophobicity even under harsh environmental conditions.

By leveraging these original structures found in nature, the researchers successfully prevented the droplets from wetting the surface and achieved improved superhydrophobicity. The newly developed structure has demonstrated significantly greater resistance to impact and water pressure compared to conventional superhydrophobic surfaces.

Superhydrophobicity is defined as the property that allows water to easily roll off without penetrating the surface. This property has numerous applications across various domains, including self-cleaning, anti-icing, and anti-fouling.

Existing superhydrophobic surfaces exhibit limitations, particularly in scenarios where the surfaces get easily wet when shock or pressure is applied to water droplets. To address these challenges, a stable anti-wetting mechanism is essential to maintain superhydrophobicity even in harsh conditions.

The research team utilized the concave structures observed in leaf beetles and soil-dwelling springtails as a basis for their work. By employing this concept, they created CP surfaces with concave cavities that exhibited stable superhydrophobicity, even when subjected to high-speed water droplet collisions and elevated hydrostatic pressures.

Experimental results indicated that the CP structure experienced approximately 1.6 times greater resistance to wetting upon impact compared to the normal pillar (NP) structure. Under high-water-pressure conditions, approximately 87% of the NP structure became wet, whereas only 7% of the CP structure experienced wetting.

The concave cavities generate an air cushion upon contact with water droplets, functioning much like a spring to prevent water penetration. As a result, the CP surface maintained a stable superhydrophobicity for over 24 hours.

Professor Lee stated, “We have introduced a new direction for the design of stable superhydrophobic surfaces. If this design is successfully implemented, it is expected to make significant contributions across various industrial applications.”