Design of Mechanical Metamaterials Fabricated Via Two-Photon Lithography and Atomic Layer Deposition

M. Diamantopoulou


mponents with high resolution down to a few nanometers. The expansion of that technology has arised a relatively new field of research at which the length scale effects of different materials combined with complex architectures have been explored for the past twenty years. Micro- and nanolattices consisting of several unit cells have been realized with the emergence of this technology. A wide variety of materials (photoresists) are utilized for achieving the low resolution feature size of 3D complex structures in the two-photon polymerization process. For modeling the behavior of structures made of various photoresist materials, researchers have investigated till now with a study-specific manner the mechanical properties of the desired photoresist with the aim of extracting information which can be used as inputs for the numerical analysis. However, a photoresist material can have properties which span over a large range and depend on primarily the fabrication parameters chosen each time. Thus, in this work an extensive study is conducted by varying the fabrication parameters of the two-photon lithography technique and utilizing this information in order to train a model that can predict the mechanical behavior of different resins. Additionally, there has been a long discussion regarding the trade-off between different properties that the microlattices exhibit. In specific, there is a sacrifice between recoverable ceramic microlattices and stiffness. It has been shown that ceramic microlattices exhibit shape recoverability upon unloading during an uniaxial compression test. The recoverability, however, deteriorates as the ceramic coating becomes thicker; simultaneously though the stiffness of the lattice is higher. Double- wall tube architecture is proposed as an alternative design to overcome this trade-off between recoverability and enhanced stiffness compared to the most investigated single-wall tube architecture.