Sweden’s Chalmers University of Technology researchers have just announced that they’ve printed a very small 3D chair with electrical properties using cellulose nanomaterials. From a June 17, 2015 news item on Nanowerk,
A group of researchers at Chalmers University of Technology have managed to print and dry three-dimensional objects made entirely by cellulose for the first time with the help of a 3D-bioprinter. They also added carbon nanotubes to create electrically conductive material. The effect is that cellulose and other raw material based on wood will be able to compete with fossil-based plastics and metals in the on-going additive manufacturing revolution, which started with the introduction of the 3D-printer.
Here’s the 3D-printed chair,
A June 17, 2015 Chalmers University of Technology press release (also on EurekAlert*), which originated the news item, describes the problem with printing from cellulose nanomaterials and how it was solved,
The difficulty using cellulose in additive manufacturing is that cellulose does not melt when heated. Therefore, the 3D printers and processes designed for printing plastics and metals cannot be used for materials like cellulose. The Chalmers researchers solved this problem by mixing cellulose nanofibrils in a hydrogel consisting of 95-99 percent water. The gel could then in turn be dispensed with high fidelity into the researchers’ 3D bioprinter, which was earlier used to produce scaffolds for growing cells, where the end application is patient-specific implants.
The next challenge was to dry the printed gel-like objects without them losing their three-dimensional shape.
“The drying process is critical,” Paul Gatenholm explains. “We have developed a process in which we freeze the objects and remove the water by different means as to control the shape of the dry objects. It is also possible to let the structure collapse in one direction, creating thin films.”
Furthermore, the cellulose gel was mixed with carbon nanotubes to create electrically conductive ink after drying. Carbon nanotubes conduct electricity, and another project at Wallenberg Wood Science Center aims at developing carbon nanotubes using wood.
Using the two gels together, one conductive and one non-conductive, and controlling the drying process, the researchers produced three-dimensional circuits, where the resolution increased significantly upon drying.
The two gels together provide a basis for the possible development of a wide range of products made by cellulose with in-built electric currents.
“Potential applications range from sensors integrated with packaging, to textiles that convert body heat to electricity, and wound dressings that can communicate with healthcare workers,” says Paul Gatenholm. “Our research group now moves on with the next challenge, to use all wood biopolymers, besides cellulose.”
The research findings are presented this week at the conference New Materials From Trees that takes place in Stockholm, Sweden, June 15-17 .
The research team members are Ida Henriksson, Cristina de la Pena, Karl Håkansson, Volodymyr Kuzmenko and Paul Gatenholm at Chalmers University of Technology.
This research reminds me of another effort, a computer chip fashioned of cellulose nanofibrils (CNF) from the University of Wisconsin-Madison (mentioned in my May 27, 2015 post).
* EurekAlert link added June 18, 2015.