The need for control of the elastic properties of architected materials has been accentuated due to the advances in modelling and characterization. Among the plethora of unconventional mechanical responses, controlled anisotropy and auxeticity have been promulgated as a new avenue in bioengineering applications. This paper aims to delineate the mechanical performance of characteristic auxetic and anisotropic designs fabricated by multiphoton lithography. Through finite element analysis the distinct responses of representative topologies are conveyed. In addition, nanoindentation experiments observed in-situ through scanning electron microscopy enable the validation of the modeling and the observation of the anisotropic or auxetic phenomena. Our results herald how these categories of architected materials can be investigated at the microscale.

We use a previously unexplored Bayesian optimization framework, “evolutionary Monte Carlo sampling,” to systematically design the arrangement of defects in an architected microlattice to maximize its strain energy density before undergoing catastrophic failure. Our algorithm searches a design space with billions of 4 × 4 × 5 3D lattices, yet it finds the global optimum with only 250 cost function evaluations. Our optimum has a normalized strain energy density 12,464 times greater than its commonly studied defect-free counterpart. Traditional optimization is inefficient for this microlattice because (i) the design space has discrete, qualitative parameter states as input variables, (ii) the cost function is computationally expensive, and (iii) the design space is large. Our proposed framework is useful for architected materials and for many optimization problems in science and elucidates how defects can enhance the mechanical performance of architected materials.

The advances in laser fabrication technologies have provided the means to create complex structural features in micro- and nanoscale. Hierarchical features, imitating natural materials, can be architected, providing remarkable mechanical performance. In addition, metamaterial structures, ranging from mechanical to bioengineering, with unprecedented properties, can be utilized for engineering applications. In this paper, we summarize conducted work on the laser-aided fabrication of architected structural and biological materials. To effectively design "meta-implants", the design and structural principles encompassing these architected materials must be comprehended and substantiated. To this end, we fabricated by multiphoton lithography 3D mechanical metamaterial structures having as the principal objective to control failure and increase the strain energy capacity of the structure. New design concepts for 3D mechanical metamaterials were also introduced, exhibiting tailored buckling for enhanced strain hardening, high energy absorption and resilience to large deformations. Furthermore, we developed the processes required to create large scale bioscaffolds, that can be utilized in biological science and biomedical engineering for in vitro models.