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Both strong and tough, using bacteria to make automotive materials

What would you think if someone told you that bacteria are not terrible and can even make engineering materials that are strong, resistant, and resilient? This is not an illusion, but the USC Viterbi School of Engineering published in “Advanced Materials”

The researchers studied a special kind of bacteria-S. pasteurii, which is known for secreting an enzyme called urease. When urease is exposed to urea and calcium ions, calcium carbonate is produced. This mineral compound is an important part of bones or teeth.

In this research, the key innovation is to guide bacteria to grow calcium carbonate minerals to obtain an ordered microstructure similar to natural mineralized composite materials. Researcher Qiming Wang said: “Bacteria know how to save time and energy to do things. They have their own wisdom. We can use their ingenuity to design hybrid materials that are better than synthetic materials.”

In fact, drawing inspiration from nature is not new in engineering. “Although microorganisms such as bacteria, fungi, and viruses can sometimes be harmful to cause disease, they can also be beneficial. We have a long history of using microbial materials for processing, such as using yeast to brew beer. But research on the use of microorganisms to make engineering materials Limited.” Qiming Wang said.

The new biological material combines live bacteria and synthetic materials together, and the mechanical properties shown are better than any current natural or synthetic materials. To a large extent, this is due to the pellet structure in the material, which is characterized by multiple layers of minerals arranged at different angles to each other, forming a “twisted” or spiral shape. This kind of structure is difficult to manufacture by synthetic means alone, so the researchers use bacteria to achieve this goal.

In order to make this material, the researchers 3D printed a grid structure with empty squares and laid the grid layers at different angles to form a spiral shape. Then, bacteria are introduced into the structure. Bacteria naturally like to attach to surfaces, so they use their “legs” to grasp the material. Next, the bacteria secrete urease, which promotes the formation of calcium carbonate crystals. They grow along the surface and eventually fill the small squares or voids in the grid structure.

“We have done mechanical tests to prove that this structure is very strong. They can also resist crack propagation and fracture, and help suppress or dissipate the energy inside the material. It can be applied to infrastructure such as aerospace panels and vehicle frames. “Doctoral student An Xin said. In addition, this active material is relatively light, and can also provide material choices for defense applications such as body armor or vehicle armor.

When repairs are needed, bacteria can even be re-added to these materials. The researchers said: “These biological materials still have the properties of self-growth. When the material is damaged, we can add bacteria to make it grow again. For example, if we apply it to the frame, we can repair the damaged material when necessary.”(More: honda brio rs

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