Fig. 2: GRACE allows printing adaptive and feature-driven prints with complex geometries.

A showcase of GRACE printing by generating targeted features around randomly distributed, fluorescently stained alginate spheres detected within the resin. a, A spherically wrapped channel network architecture is generated around the alginate spheres, showing the process from acquiring the raw data to generating the target model (shown rendered) and, finally, printing and imaging the resultant construct. The light-sheet sections at different depths of the printed gel show in greyscale the stained GelMA and the cross-sections of the convoluted channels printed within the gel, whereas the unstained particles are circled in red (or in green) to improve visualization and to distinguish them from cross-sections of the channels. Scale bars, 1 mm. b, Interconnection of randomly distributed alginate spheres with printed struts, showing a render of the target geometry (blue) and resultant light-sheet reconstruction in 3D after printing. c, Encapsulation, with corresponding light-sheet 3D reconstruction post-printing indicating presence of spheres. Scale bar, 1 mm. d,e, Parametric discrimination of generated features based on size (d) or spectral emission (e). Here different populations receive either a single grazing channel or a more complex spherical channel network. Scale bars, 2 mm. f, Automated alignment of a cartilage model to femoral head in a two-part sequential print, with computation for the alignment (post-scanning) taking <5 s to perform on a common personal computer. Our transformed cartilage model was printed directly onto the femoral head, resulting in a multicomponent sequentially printed construct with correct relative positioning of its components. Scale bar, 2 mm.