Manufacturing of multiscale structured surfaces

Multiscale structured surfaces are a way to provide advanced, otherwise not attainable functionality on a technical part. Applications of such parts can be manifold, and numerous works have already covered the transfer of natural examples into bio-inspired surfaces or the geometrical and functional metrology of such surfaces. After briefly presenting typical functionalities of multiscale structured surfaces, this keynote paper will focus on the available manufacturing processes and review their capabilities to generate multiscale structured surfaces. To compare such processes, the so-called “multiscality” is defined that characterizes the structured surfaces according to the lateral and vertical extent of the individual stacked elements and is used as a first indicator to assess the difficulty of their manufacture. As the boundaries of what is considered a multiscale structure are diffuse, ranges of low, medium and high multiscality are defined instead. After presenting the state of the art of manufacturing processes currently utilized for the manufacture of (not only multiscale) structured surfaces, this keynote paper summarizes the capabilities of single-step and multi-step/multi-physics approaches for their applicability across different scales and gives an outlook on which processes could potentially become relevant in the future.