Biocomposite mineralized after 3D printing


Lausanne – A team at the Swiss Federal Institute of Technology Lausanne (EPFL) has developed an ink for 3D printing that contains a bacterium. Under certain conditions, it triggers a process that transforms the material of the printed object into biocomposite. It is light and strong, porous and solid.

Using an EPFL ink called BactoInk, the material of any 3D-printed object transforms into a mineralized biocomposite in four days or less. This is achieved by the live bacterium Sporosarcina pasteurii, which is added to the ink. When exposed to a solution containing urea, it triggers a mineralization process that produces potassium carbonate.

According to an EPFL statement, at the end of this mineralization process, the material has properties that are extremely difficult to produce in a laboratory or factory, especially using environmentally friendly materials and processes: Like bone or shell, it is light and strong, porous and solid. A corresponding study has now been published in the trade medium “materials today”.

As the head of the soft materials laboratory in the EPFL School of Engineering, Esther Amstad, explains, the structures previously made from 3D printing inks with the addition of minerals tend to develop cracks or shrink the object. “So we came up with a simple trick: Instead of printing minerals, we printed a polymer scaffold with our BactoInk, which is then mineralized in a second, separate step.” After about four days, the mineralization process triggered by the bacteria in the scaffold results in a final product with a mineral content of over 90 percent, he said.

As she continues, these composites resemble natural materials more than today’s synthetic composites. Potential applications reportedly range from restoring artwork to building artificial coral reefs to repairing bones. mm