4D printing with plant-like behaviour. Via Harvard Gazette
As the world gets to grips with what 3D printing is, what it can and cannot do and where it can be used to add real value, 4D printing comes in to take its place and invite the same lot of questions all over again.
The technology has been in existence for some time but there are conflicting views as to what 4D printing actually is. We have heard various interpretations of these ‘self-printing objects’ form Nervous System's technology where a print is condensed into a small build platform and unfolds into its intended shape to Skylar Tibbits’ self assembly and programmable material technologies coming out of MIT’s Self-Assembly Lab and even 5D PRINTING at Autodesk.
Now researchers at the Wyss Institute for Biologically inspire Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences, have introduced a different take on 4D printing with a technology, inspired by plant life, that can produce structures which change shape when immersed in water.
The study was carried out by senior author and Voxel8 Co-founder, Jennifer Lewis and a team of science and mathematics researchers specialising in evolutionary biology, material physics and composite printing.
Mimicking the nature of plant life, the technology deposits hydrogel structures containing cellulose fibrils which resemble the microstructures found in plants that cause them to change shape according to their environments. During printing, the tiny cellulose are aligned on a flat print bed to allow swelling and stiffness, which can be predicted and controlled to produce intricate shape changes when immersed in water. A variety of hydrogel materials can be used to produce different responses from the stimuli. The method works with a proprietary mathematical model, which determines how a 4D object must be printed in order to achieve determined transformable shapes.
Print is immersed in water to activate transformation.
“Using one composite ink printed in a single step, we can achieve shape-changing hydrogel geometries containing more complexity than any other technique, and we can do so simply by modifying the print path,” said A. Sydney Gladman, a graduate research assistant specialising in the printing of polymers and composites at the Wyss Institute and SEAS. “What’s more, we can interchange different materials to tune for properties such as conductivity or biocompatibility.”
“This work represents an elegant advance in programmable materials assembly, made possible by a multidisciplinary approach,” Lewis, commented. “We have now gone beyond integrating form and function to create transformable architectures.”
Potential future applications for this type of 4D printing technology include smart textiles, soft electronics and even to grow new organs.