- Harvard scientists mimic plant cell alignment to allow for control over 3D-printed objects.
- This NSF-funded research is the first to harness time in its implementation.
- 4D printing points the way to arbitrary shape design with a broad range of medical and industrial applications.
A team of scientists at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences has taken 3D printing into the fourth dimension – time.
In nature, flowers and plants have tissue compositions and microstructures that result in dynamic shapes that change according to their environments. Inspired by these natural objects, the team has unveiled 4D-printed structures that change shape when immersed in water.
“This work represents an elegant advance in programmable materials assembly, made possible by a multidisciplinary approach,” says Jennifer Lewis, senior author on the new study. “We have now gone beyond integrating form and function to create transformable architectures.”
The 4D-printed hydrogel composites appear in a new study in Nature Materials. Lewis and her team programmed them to mimic the variety of shape changes undergone by plant organs. The hydrogel composites contain cellulose fibrils that are derived from wood and are similar to the microstructures that enable changes in plants.
Lewis’s team encodes the hydrogel composite ink with swelling and stiffness to produce intricate changes. They reach a desired shape thanks to a proprietary mathematical model that is able to predict what the inverse printing path must be for a 4D object to achieve a desired shape.
“What’s remarkable about this 4D printing advance is that it enables the design of almost any arbitrary, transformable shape from a wide range of available materials with different properties and potential applications," says Wyss Institute founding director Donald Ingber. “It truly establishes a new platform for printing self-assembling, dynamic microscale structures that could be applied to a broad range of industrial and medical applications.”
The Army Research Office (ARO) and the National Science Foundation’s Materials Research Science and Engineering Center (MRSEC) provided the funding to support this research.
