A group of scientists at the University of Coimbra (UC) uses cellulose from bacteria for 4D printing to be environmentally friendly and sustainable.

The development of these materials brings countless possibilities for use: devices where there is no electrical power, intelligent clothing for athletes in high competition that regulates perspiration depending on the ambient temperature, biomedical devices, and others.

The group of researchers, eager to make a "green" transition from 3D to 4D printing, have used bacteria as "living tools" in the production of cellulose, a highly versatile natural polymer.

After the process of selecting the bacteria that would best serve the project, there was work to obtain the cellulose needed to produce a material that would make 4D printing possible.

Ana Paula Piedade, researcher at CEMMPRE - Centre for Mechanical Engineering, Materials and Processes - at FCTUC, explained that the raw material obtained was mixed "with dissimilar polymers (with different properties of each of the celluloses) and, from there, we produced the biocomposites and developed the filaments suitable for 4D printing". And, since the raw material undergoes metamorphosis in contact with different environments, the biggest challenge is to guarantee the return to its original form. This reversibility of the material continues to be a challenge, although "4D technology allows the material to transform and then return to its original form", assured Ana Paula Piedade.

The technology now developed is sustainable and low-cost, because the bacteria only need "food" (which can be, for example, food waste) to produce cellulose, and environmentally friendly.

"Ninety-seven percent of the material used stays in the part itself that is printed, that is, the residue produced is minimal and, even so, this residue can be used for the production of more filaments," stresses Ana Paula Piedade.

The next phase of the research will focus on the design of structures for specific applications, namely the design of devices that can take advantage of this 4D effect.

"We will explore different approaches to manufacturing 4D devices, because you have to think very carefully about how you are going to print, define the geometry of what you are going to print, and optimize processes that ensure the 4D effect," he concludes.

Financed in the amount of 250 thousand euros by the Fundação para a Ciência e a Tecnologia (FCT) and by European funds (COMPETE 2020), the project counts with the collaboration of the Instituto Politécnico da Leiria (IPL).

Source: lmagazine