Microextrusion-based 3D printing for the free-shape deposition of functional cellulose-based electronic materials

Cellulose is the most abundant renewable biomaterial, featuring a wide range of applications. In the form of aqueous suspension of microfibrils, it is also highly processable, which has opened new doors to a number of industrial applicative scenarios. In particular, extrusion 3D printing enables the free-form fabrication of stable cellulose-based constructs with applications, among others, in flexible electronics. However, most of these devices still rely on costly metal elements and show a relatively low cellulose fraction, mainly associated to the substrate. Here, we applied an optimization strategy to the microextrusion-based 3D printing of microfibrillated cellulose/hydroxypropylcellulose composites, which were further modified by the addition of nanocarbon and doped ZnS powders, thus endowing the materials with conductive and electroluminescent properties, respectively. The formulations were also demonstrated to be non-cytotoxic and, in principle, suitable for application in contact with living matter. In conclusion, we fabricated and integrated cellulose-based 3D printed materials with a broad applicative potential ranging from flexible electronics to biocompatible devices, potentially leading to the development of a new class of cellulose-based (bio)electronic components with reduced environmental impact.