Design and Fabrication of Bioinspired Engineering Surfaces


Student thesis: Doctoral Thesis

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Awarding Institution
  • Zuankai WANG (Supervisor)
Award date19 May 2020


After millions-years of evolution for adaption and optimization, natural living organisms are often endowed with rich morphologies and chemical compositions to fulfill specific functions, mimicking which allows us to invent new materials. Despite extensive advances in micro/nano fabrication techniques have made it possible to fabricate artificial surfaces that with desired size, composition, and wettability, our materials selection is still restricted in a narrow spectrum. Moreover, our ability to rationally design surface topography as well as chemical composition to achieve preferential performance remains limited, which severely hinder the practical application of functional biomimetic surfaces. This thesis aims to develop the strategies for the design and fabrication of various bioinspired surfaces with specific functions, and explore how surface topography regulate the solid-liquid-gas triple phase interactions. The thesis would not only advance our fundamental understanding of the interfacial interactions, but also provide guidance for the design and fabrication of engineering surfaces to mimic the functions of natural creatures. In the long run, the rationally designed artificial surfaces are expected to achieve superior functions that even go beyond the natural counterparts.

Firstly, we demonstrate that it is possible to transform the disordered distribution of condensate droplets into ordered arrays on the chemically homogeneous but physically heterogeneous cavity-patterned surfaces, a phenomenon that has not been systematically investigated in a previous study. Such a disorder-to-order transition demands an exquisite competition between the length scales of droplets and cavities. In particular, the confinement effect imposed by patterned cavities should be well controlled to allow for the energetically favorable transition. This study would not only enrich our fundamental understanding of the interplay between droplets dynamics and surface topography, but also provide guidance for the design of surface topography for many practical applications.

Secondly, inspired by the cuticles of springtails, we designed and fabricated hierarchical doubly reentrant structures by direct laser writing lithography technique, which solves the dilemma between high static repellency and pressure resistance. The top layer of the hierarchical structures is designed to have smallest size, which serves to minimize the liquid-solid contact area to preserve a high static repellency, while the lower layer with a larger cover could further enhance the pressure resistance. Such hierarchical structures well overcome the limitation of conventional single layered structures, and thus would provide important insight for the development of novel biomimetic structures.

Finally, we developed a technique to replicate the sophisticated natural and biomimetic structures based on configurable, elastic crack engineering, which transforms the detrimental crack effect into a powerful tool for the faithful, scalable, and cost-effective fabrication of various hierarchical structures on a wide range of engineering materials. The use of crack engineering dramatically enriches the freedom and flexibility in the design of materials to mimic various natural living organisms, and paves the road for translating nature’s inspirations into real-world applications.