Towards the optimal design of micro-structured surfaces: from micro-fabrication to surface characterization

Low-free-energy-surfaces own remarkable engineering performances in many fields ranging from self-cleaning solar panels to airplane wings and biomedical implants. A large number of studies have shown that both the surface chemistry and the micro-textures strongly influence the adhesion properties of materials offering a broad variety of alternatives to engineer low-free-energy surfaces. However, their optimal design still encounters several issues both from fabrication and characterization standpoint. In this thesis, some micro-fabrication and surface characterization techniques have been exploited to provide new ideas and concepts for the optimal surface design. First, 13 samples have been fabricated using cone shaped elements with different geometrical dimensions and then contact angle measurements have been carried out to characterize the wetting properties of the surface. Then, a microstructure printed on a deformable substrate has been designed and optimized to achieve a reversible switch from hydrophobic to super-hydrophobic behaviour. The experimental results show that a trade-off between the best surface properties and the minimum mechanical deformations is needed in order to improve the long term reliability of the engineering surfaces.