The collection of scaffolding geometries is designed with the support of NX-12 (Siemens PLM Solutions) as main computer-aided design and engineering software (CAD-CAE). Solid- and surface-based operations are employed to create trusses, unit elements and building blocks, whose replication and hybridization using matrix, Boolean and recursive tools lead to complex-shape scaffolds with biomimetic features. The simulation capabilities of NX-12 are applied to the evaluation of performance, including mechanical and fluidic properties, and the creation of design maps. Additional CAD and computer-aided manufacturing (CAM) resources are used to incorporate special surface features to the generated lattices, which may enable innovative cell-material interaction studies, and to evaluate manufacturability and analyze the impact of geometrical modifications performed following design for additive manufacturing strategies.

In this regard, it is important to highlight the use of 3D Coat (Pilgway), which is used as digital sculpting software to generate real printable topographies by mapping previously generated grayscale masks upon the surfaces of three-dimensional CAD models. CAD texturing is normally performed following two main families of methods, bump or texture mapping and displacement mapping. The former modifies the surface normals of designed objects and use the perturbed normals during light calculations, to simulate bumps and wrinkles and achieve realistic rendering, but without actually modifying the surface geometry. The latter apply heightmaps to cause a real effect (including a modified stereolithographic or “stl” file for printing purposes), by displacing points or voxels of the designed surfaces, according to the value of the heightmap applied to each point of the surface. 3D Coat enables both approaches but, in for the creation of a subset of textured scaffolding geometries for present OS library, we resort to the real surface modifications achievable through displacement mapping for the third step of the design process.  

Considering that the collection is arranged for the manufacturing of scaffolds applying a wide set of AMTs, two slicers are used as supporting CAM tools. First of all, Chitubox v.1.9.1 (ChiTu Systems) is utilized as key reference slicer for digital light projection, stereolithography and LCD printing. In short, the software slices CAD models and generates black and white digital masks that can be used for digitally processing photopolymers and slurries. The printability of multimaterial constructs and the impact of mesh quality on the generated masks’ resolution can be analyzed thanks to Chitubox. Together with this slicer, Ultimaker Cura 4.13.1 is employed as state-of-the-art slicer for generating printing paths for fused-deposition modeling, inkjet printing systems and bioprinters, among others. Both of them are user-friendly free slicers that reinforce the open-source approach of the generated collection and help to make 3D printing accessible to users worldwide. Their application is extremely extended and their options for fine-tuning the eventually needed supporting structures constitute interesting resources for R&D tasks and towards final productivity and sustainability, which is connected to minimizing the volume of printable supports.

With these CAD-CAE-CAM resources, six (1-6) main subsets of OS scaffolds are designed, evaluated, optimized and shared as digital libraries through different channels: 1) a collection of unit cells as standard scaffolding geometries; 2) a collection of multiscale, hierarchical, recursive or fractal-like scaffolds for their biomimetic interest; 3) a set of functionally-graded constructs; 4) a set of combinations of the previous geometries to exemplify the versatility and complexity achievable through multimaterial additive manufacturing; 5) an assortment of cell scaffolding textures with systematic variations; and 6) a subset of microtextured lattices to evaluate the potentials of scaffolds with design-controlled topographies (these two last subsets 5-6 shared as companion library of textured test probes).

Table below summarizes selected designs from the open-source scaffolds libraries (monomaterial):

Table below summarizes selected designs from the open-source scaffolds libraries (multimaterial):