Activity: Examinations and supervision › Supervisor activities
In this thesis report, the intersection of bio-inspired surfaces and additive manufacturing is investigated, with the aim of determining the feasibility and viability of leveraging 3D printing technologies to rapidly prototype surfaces that mirror those found in nature. While both of these areas are heavily researched, the overlap of the two is an area filled with endless potential, ranging from the medical industry to product design and much more. The ability to rapidly and inexpensively reproduce bio-inspired surfaces using conventional 3D printing at microscale would thus serve to enable the scientific community to conduct optimisation of 3D surface model designs and printing process parameters. This would allow for improved forecasting of surface properties before investment in nano-fabrication takes place. However, as biological surfaces display divergent and numerous features, this report utilises the gecko toes, known for their dry adhesion properties, as a case study and a basis for investigation. As a point of departure, a literature geometry based on the gecko toe is used as a benchmark. With reference to the research consulted in the duration of this project, this report identifies multi-hierarchical structures, feature geometry, feature density, and manufacturing methods used as the key determinants of how well 3D printing can emulate the intricate features of the gecko’s toes. In this regard, Stereolithography (SLA) and Direct Light Processing (DLP) are characterised via experiments involving translating a simplification of the gecko toes features derived from the literature (literature sample) into a CAD model, and thereafter printing the model while manipulating different process parameters. In this particular case, DLP was found to outperform SLA in relation to features sizes, tolerances and other qualitative and quantitative criteria. As such, this thesis focuses on DLP as the most promising manufacturing method for the purpose of this project’s aim. Based on conducting a wettability test (water drop angle measurement), it was determined that smaller and more intricate designs showed better wettability properties compared with the simplified literature geometry. This is indicative of that the simplification of bio-inspired surfaces is likely detrimental to the emergent properties of the replicated geometry. Hence, the capabilities of 3D printing geometries to print smaller, denser an more complex surface features should enable a closer match between synthetic bio-surfaces and real ones.