Researchers at Chalmers University of Technology have 3D printed an object made entirely by cellulose for the first time using a 3D bioprinter.
As an organic compound, cellulose is the main component of cell walls in green plants and therefore the most abundant organic polymer on Earth. It has so far not been used in additive manufacturing processes, as it does not melt when heated. This is why wood filament, for example, consists of a mixture of PLA thermoplastic and tiny wood particles.
However, a breakthrough has now been accomplished by Professor Paul Gatenholm and his team at Wallenberg Wood Science Center. For the first time, they have 3D printed cellulose from wood using a 3D bioprinter. By mixing cellulose nanofibrils in a hydrogel consisting of 95 to 99 percent water, they obtained a gel that was then 3D printable. The next critical step was to dry the objects without them losing their shape. “The drying process is critical,” explains Paul Gatenholm. “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.”
In an additional step, carbon nanotubes were mixed into the cellulose gel, creating electrically conductive ink after drying. Combining the two gels, the team was able to produce 3D circuits.
“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.”