Rice and Butterfly Wing Effect Inspired Low Drag and Antifouling Surfaces: A Review

In this article, a comprehensive overview of the reported rice and butterfly wing effect discovered by the authors is presented with the hope to attract and inspire others in the field. Living nature has inspired researchers for centuries to solve complex engineering challenges with much attention given to unique structures, materials, and surfaces. Such challenges include drag reducing and antifouling surfaces to save energy, lives, and money. Many flora and fauna exhibit low drag and antifouling characteristics, such as shark skin and lotus leaves, due to their hierarchical microstructured morphologies. The authors have reported that rice leaves and butterfly wings combine the shark skin (anisotropic flow leading to low drag) and lotus leaf (superhydrophobic and self-cleaning) effects, producing the so-called rice and butterfly wing effect. Such surfaces have been fabricated with photolithography, soft lithography, hot embossing, and coating techniques. Fluid drag, anti-biofouling, anti-inorganic fouling, contact angle, and contact angle hysteresis results are presented to understand the role of sample morphology. Conceptual modeling provides design guidance when developing novel low drag and antifouling surfaces for medical, marine, and industrial applications.