A limitation, when it comes to 3D printed biomimetic structures with micrometer and sub-micrometer precision are computer aided design (CAD) programs. Existing CAD software is usually based on “manual” step-by-step design principles intended and suitable for subtractive and formative manufacturing methods rather than organic designs for additive manufacturing. The resulting structures can hence deviate strongly from their natural tissue counterparts and small design changes of complex objects usually result in time consuming workflows [1–4]. Alternatively, tissue imaging dataset derived designs have been used[3,5] to recapitulate native geometries accurately, but lack systematic variation and adjustment of individual design parameters.
Algorithmic design based on parametric and algorithmic modelling provides an alternative and allows to efficiently explore and optimize geometries based on a set of logical operations and user defined rules.[6–8] Algorithmic design algorithms can yield hierarchical branching patterns resembling those found in nature[4,8] and enable scalable design automation (e.g. scan to print).
To experimentally realize perfusable biomimetic microtissue, we designed an alveoli network using algorithmic design principles. This lead to a set of hollow alveoli surrounded by a capillary network (A). Both alveoli and capillaries can be contacted via distinct in- and outlets for cell seeding, medium perfusion and tidal ventilation. This algorithmic design approach allows for deliberate design permutations such as alveoli size, degree of vascularization and wall thickness (B). Using dip-in mode TPS printing, the algorithmic design was printed both with acrylate-based resin and imaged with scanning electron microscopy (C, left), as well as with gelatin-based resin and imaged with two-photon fluorescence microscopy (C, right).