A team of researchers from Chalmers University of Technology in Sweden have developed an innovative technique for 3D printing wood-based inks in a way that closely mimics the ultrastructure of natural wood. The ability to recreate the cellular architecture of wood using 3D printing could open up countless opportunities in the creation of green products derived from trees, including clothes, furniture, packaging, personal care products and more.
Like all plants and natural materials, trees have unique properties that enable them to grow and withstand and thrive in certain environments. Wood—as can be visualized by the grain—has specific properties in terms of porosity, toughness and torsional strength. Unfortunately, these properties are difficult to maintain in the processing of wood, which requires sawing, planing or curving. Other wood processing techniques, for making products like paper or textiles, completely do away with the underlying ultrastructure and architecture of wood cells.
The new technique pioneered by the researchers at Chalmers University, however, enables wood to be printed into the shape of products while recreating the natural ultrastructure of the material, thus capturing the strength and properties of natural wood.
The process relies on a wood-based ink previously developed by the team of researchers, which was created by converting wood pulp into a printable nanocellulose gel. Now, the research team has found a way to interpret wood’s genetic code and instruct a 3D printer to replicate the ultrastructure of wood.
“This is a breakthrough in manufacturing technology,” commented Professor Paul Gatenholm, project leader at the Wallenberg Wood Science Centre at Chalmers. “It allows us to move beyond the limits of nature, to create new sustainable, green products. It means that those products which today are already forest-based can now be 3D printed, in a much shorter time. And the metals and plastics currently used in 3D printing can be replaced with a renewable, sustainable alternative.”
The researchers also found that by adding hemicellulose—a component of plant cells—to the 3D printable ink, the material became stronger, resembling the process of lignification, where cell walls are built.
The breakthrough in wood 3D printing could lead to the development of innovative wood-based products that can be designed and “grown” at faster turnaround times than natural wood products.
Among the products being explored by the research group is a packaging concept consisting of honeycomb structures with chambers between the printed walls. In this experiment, the researchers demonstrated the ability to encapsulate solid particles inside those chambers. Because of cellulose’s oxygen barrier properties, the 3D printed structure could be an effective form of packaging for food or pharmaceuticals.
“Manufacturing products in this way could lead to huge savings in terms of resources and harmful emissions,” Gatenholm added. “Imagine, for example, if we could start printing packaging locally. It would mean an alternative to today’s industries, with heavy reliance on plastics and C02-generating transport. Packaging could be designed and manufactured to order without any waste.”
Interestingly, the researchers also believe their 3D printing technology could be used in space. To date, the team has already demonstrated the process at a workshop at the European Space Agency (ESA) and is working with Florida Tech and NASA to test the materials in microgravity environments.
“The source material of plants is fantastically renewable, so the raw materials can be produced on site during longer space travel, or on the moon or on Mars. If you are growing food, there will probably be access to both cellulose and hemicellulose,” said Gatenholm. “Traveling in space has always been the catalyst for material development on earth.”
The full study, “Materials from trees assembled by 3D printing – Wood tissue beyond nature limits”, was recently published in the journal Applied Materials.