3D printable ink containing bacteria will be used in many fields

“For example, they must behave like a solid when at rest but still be extrudable through a 3D printing nozzle – sort of like ketchup," she adds.

Amstad notes that while microscopic mineral particles have been added to 3D printing inks in the past to meet some of these flow requirements, the resulting structures have a tendency to be soft or to shrink after drying, which causes cracking and a loss of control over the shape of the finished output.

The power of 'BactoInk'

Amstad states this innovative approach can be applied in several fields, including biology, ecology, and even the arts. Moreover, cracks or chips in a statue can be treated with BactoInk by injecting it right there.

“The versatility of the BactoInk processing, combined with the low environmental impact and excellent mechanical properties of the mineralized materials, opens up many new possibilities for fabricating lightweight, load-bearing composites that are more akin to natural materials than to today’s synthetic composites,” Amstad says.

EPFL's study was published in Materials Todayon February 18.

Study abstract:

Nature fabricates organic/inorganic composites under benign conditions, yet, in many cases, their mechanical properties exceed those of the individual building components it is made from. The secret behind the evolutionary pivot is the unique ability of nature to control structure and local composition of its materials. This tight control is often achieved through compartmentalization of the reagents that can be locally released. Inspired by nature, we introduce an energy-efficient process that takes advantage of the compartmentalization to fabricate porous CaCO3-based composites exclusively comprised of nature-derived materials whose compressive strength is similar to that of trabecular bones. The unique combination of nature-derived materials, 3D printability, and good mechanical properties is achieved through the formulation of these materials: We combine microgel-based granular inks that inherently can be 3D printed with the innate potential of engineered living materials to fabricate bacteria-induced biomineral composites. The resulting biomineral composites possess a porous trabecular structure that comprises up to 93 wt% CaCO3 and thereby can withstand pressures up to 3.5 MPa. We envisage this system to have the potential to be used in art restoration, serve as artificial corals to help the regeneration of marine reefs, and, with additional work, might even allow the reparation of broken or partially disintegrated natural mineral-based materials such as certain parts of bones.