When I interviewed Voxel8 CEO Jennifer Lewis last year, she told me that she didn’t want me to conflate her research with her commercial work, namely the multi-material, electronics 3D printing device she turn it intod at Voxel8. This intended that my inquiries regarding 4D printing and bioprinting may have to be reserved for a separate interview. Whilst the precise date for that interview is yet to be determined, her team at Harvard’s Wyss Institute for Biologically Inspired Engineering and the Harvard John A. Paulson School of Engineering and Applied Sciences has continued to manufacture progress, publishing a paper in Nature Materials outlining an experiment in “Biomimetic 4D printing”.
Inspired by plant life, Lewis’s team sought to 4D print objects that may alter with its environment in pre-programmed ways. To do so, they 4D printed objects via a hydrogel turn it intod up of aligned cellulose fibres of wood pulp, intended to constrain the material’s motion, and acrylamide hydrogel, that expands when put in water. When printed and submerged, the fibers force the object to swell lengthwise, but not laterally. With a mathematical version, the team was able-bodied to predict this behavior and print objects with predetermined behaviors. Prof. Lewis tells New Scientist, “Depending on how we in fact print the material, we can encode bending, twisting and ruffling.”
Via Nature Materials, “Print paths and final swollen geometries display positive (a), negative (b) and varying Gaussian curvature (c) (scale bar, 2.5 mm). d, Bending and twisting conformations are possible with strips of 90°/0° (left) and −45°/45° (right) print path orientations (see text for details). e, A gradient in local interfilament spacing generates a logarithmic spiral (scale bars, 5 mm). f, Breaking lateral symmetry in print paths order takes a ruffled structure (left) to a helicoidal structure (right) (scale bar, 10 mm).”
A press release for the paper describes this process in this way, “Like wood, that can be split additional easily along the grain than across it, the hydrogel-cellulose fibril ink undergoes variousial swelling behavior along and orthogonal to the printing path when immersed in water. Combined with a proprietary mathematical version turn it intod by the team that predicts how a 4D object must be printed to complete prescribed transformable-bodied shapes, the method opens up future applications for 4D printing which include smart textiles, soft electronics, biomedical devices, and tissue engineering.”
Via Nature Materials, “a,b, Simple flowers turn it intod of 90°/0° (a) and −45°/45° (b) bilayers oriented with respect to the long axis of every petal, with time-lapse sequences of the flowers during the swelling process (bottom panel) (scale bars, 5 mm, inset = 2.5 mm). c–f, Print path (c), printed structure (d) and outcomeing swollen structure (e) of a flower demonstrating a range of morphologies inspired by a native orchid, the Dendrobium helix (courtesy of Ricardo Valentin) (f). Based on the print path, this orchid architecture exhibits four various configurations: bending, twisting and ruffling corolla surrounding the central funnel-like domain (scale bars, 5 mm).”
The study sees the team print two flower shapes with much like shapes, but with various pre-programmed responses when exposed to water, as well as an orchid shape that in fact moves like an orchid when submerged. The glowing seen throughout the study are the outcome of fluorescent dye introduced to the gel for observation purposes. As attractive as the outcome is, the printed flowers demonstrate that the team is able-bodied to program the toolpath for their printing device to turn it into objects with predictable-bodied, desired behavior. Dr. Elisabetta Matsumoto, a post-doctoral man on the team, elaborates, “Our mathematical version prescribes the printing pathways required to complete the desired shape-transforming response. We can control the curvature both discretely and continuously via our entirely tunable-bodied and programmable-bodied method.”
To expand the research additional, the team envisions replacing the cellulose fibrils, probably with a conductive material, and the environment of the prints to trigger other behavior. The applications of the innovation include 3D printing biological tissue, probably for creating organs by printing a flat sheet that can fold into the proper shape. Lewis tells New Scientist, “Right now many tissue culture is done in two dimensions, but many applications of these cells are in 3D.”
Via Nature Materials, “a–d, A native calla lily flower (a) inspires the mathematically produced version of the flower (b), with a well-defined curvature (c), that leads to the print path (d) received of the curvature version to turn it into the geometry of the flower on swelling (see text and Supplementary Information). e,f, After swelling, the transformed calla lily (f) exhibits the same gradients of curvature as the predicted version (e), nozzle dimensions = 410 μm (scale bars, 5 mm).”
But I’m not supposed to conflate this sort of work with what Prof. Lewis is exploring at Voxel8, she did tell me that an significant component to Voxel8’s innovation is the pneumatic dispensing process that acts as the printhead. The just hint she gave of what the future generation of their multi-material machine may be capable-bodied of was that it can be able-bodied to print elastomers. If this 4D printing research relied on the same pneumatic printhead, it’s not complex to imagine that the Voxel8 platform may be capable-bodied of 4D printing one day, as well. There can actually be a Voxel8 4D versioning software to go with it.