Smart packaging and textiles are future uses for 3D printed cellulose
As 3D printing is used in an increasing number of settings and applications, the search for new materials has taken off. Exciting new research comes out of Chalmers University of Technology in Sweden where researchers have managed to print and dry three-dimensional objects made of cellulose for the first time with the help of a 3D-bioprinter.
Many 3D printers use plastic filament made of PLA and ABS, materials with several characteristics that make them suitable for 3D printing, including the fact that they are soft and moldable when heated and that they return to a solid state when cooled. But as 3D printing is used in an increasing number of settings and applications, the search for new materials has taken off. Exciting new research comes out of Chalmers University of Technology in Sweden where researchers have managed to print and dry three-dimensional objects made of cellulose for the first time with the help of a 3D-bioprinter.
“Combing the use of cellulose to the fast technological development of 3D printing offers great environmental advantages,” says Paul Gatenholm, professor of Biopolymer Technology at Chalmers and the leader of the research group in a statement. “Cellulose is an unlimited renewable commodity that is completely biodegradable, and manufacture using raw material from wood, in essence, means to bind carbon dioxide that would otherwise end up in the atmosphere.” The researchers believe that cellulose can compete with other 3D printing materials such as metal and plastic.
Since cellulose can’t be melted, the scientists had to find a way to work around this limitation. They integrated the bio-based material into a hydrogel consisting of 95 to 99 % water. The gel could then be dispensed into the researchers’ 3D bioprinter. The next challenge was to dry the printed structures and keeping them intact. “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.”
While printing with cellulose was one research goal, the scientists went a step further and made the material conductive by integrating carbon nanotubes. The nanotubes were also used in a hydrogel and by using the two gels together and controlling the drying process, the researchers produced three-dimensional circuits where the resolution increased significantly upon drying.
A renewable conductive material has an almost unlimited number of applications ranging from smart packaging to textiles with integrated electronics to wound dressings that can communicate with healthcare workers. As a next step, the research team is expanding their 3D printing efforts from cellulose to all wood biopolymers.
Photos: Peter Widing