A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 3 5 6 3D PRINTSHOP BIOCOMPOSITE USES BACTERIA TO INDUCE MINERALIZATION Researchers have developed a 3D- printable ink that contains a bacterium and uses a two-step process to mineralize the material within days. The resulting material could be used alongside coral reefs, bone, and in art repair. The ink, dubbed BactoInk, contains Sporosarcina pasteurii, a bacterium which, when exposed to a urea-containing solution, triggers a mineralization process that produces calcium carbonate (CaCO3). Esther Amstad, the lab head at Ecole Polytehcnique Fédérale de Lausanne, says, “instead of printing minerals, we printed a polymeric scaffold using 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 leads to a final product with a mineral content of over 90%.” The result is a strong and resilient biocomposite, which can be produced using a standard 3D printer and natural materials, and without the extreme temperatures often required for manufacturing ceramics. Final products no longer contain living bacteria, as they are submerged in ethanol at the end of the mineralization process. Amstad believes that the restoration of artworks could be greatly facilitated by BactoInk, which can also be directly injected into a mold or target site—a crack in a vase or a chip in a statue, for example. The ink’s mechanical properties lend it the strength and shrinkage resistance necessary to repair a work of art, as well as prevent further damage during the restoration process. The method uses only environmentally friendly materials and produces a mineralized biocomposite, which makes it a promising candidate for building artificial corals, which can be used to help regenerate damaged marine reefs. Finally, the fact that the biocomposite’s structure and mechanical properties mimic those of bone could potentially make it interesting for future biomedical applications. www.epfl.ch/en. OPTIMIZING COMPOSITION FOR 3D PRINTING ON MARS Parts 3D printed using a mix of Martian rock dust and a titanium alloy show promise to build tools or rocket parts on the planet Mars. The parts were made by Washington State University researchers with as little as 5% up to 100%Martian regolith, a black powdery substance meant to mimic the rocky, inorganic material found on the surface of the red planet. While the parts with 5% Martian regolith were strong, the 100% regolith parts proved brittle and cracked easily. Still, even high-Martian content materials would be useful in making coatings to protect equipment from rust or radiation damage, says Amit Bandyopadhyay, corresponding author on the study published in the International Journal of Applied Ceramic Technology. Bandyopadhyay first de- monstrated the feasibility of this idea in 2011 when his team used 3D printing to manufacture parts from lunar regolith, simulated crushed moon rock, for NASA. Since then, space agencies have embraced the technology, and the International Space Station has its own 3D printers to manufacture needed materials on site and for experiments. For this study, Bandyopadhyay along with graduate students Ali Afrouzian and Kellen Traxel, used a powder- based 3D printer to mix the simulated Martian rock dust with a titanium alloy, a metal often used in space exploration for its strength and heat-resistant properties. As part of the process, a high-powered laser heated the materials to over 2000°C. Then, the melted mix of Martian regolith-ceramic and metal material flowed onto a moving platform that allowed the researchers to create different sizes and shapes. After the material cooled down, the researchers tested it for strength and durability. wsu.edu. BactoInk could be used to restore damaged artworks. Courtesy of Eva Baur. A mix of Martian rock and titanium alloy could be used to 3D print parts on Mars. Courtesy of NASA.
RkJQdWJsaXNoZXIy MTYyMzk3NQ==