Researchers from Johns Hopkins University in Baltimore have created a material that can change its stiffness based on the force applied. This development could lead to materials that can reinforce themselves to stop damage.
Sung Hoon Kang, senior study author and assistant professor in the Department of Mechanical Engineering at the Hopkins Extreme Materials Institute says, “Imagine a bone implant or a bridge that can self-reinforce where a high force is applied without inspection and maintenance. It will allow safer implants and bridges with minimal complication, cost and downtime.”
Researchers have tried creating self-reinforcing materials before, but they’re difficult to create and the process is expensive. Previous attempts have also required active management and have a limit to how much force they can take.
Kang and his colleagues immersed polymer films made from materials that can take a mechanical force and turn it into an electrical charge in a fluid that was like blood plasma. They let the materials soak in the fluid, and they noticed that minerals began forming on the surface. They also found out that by changing the ion composition of the fluid, they could change the types of minerals that formed on the surface.
The researchers then anchored a beam and slowly increased the stress from one end of the materials to the other. The parts of the materials that had more stress applied had a larger mineral build-up, and the height of the minerals was proportionate to the square root of the force applied. "Our findings can pave the way for a new class of self-regenerating materials that can self-reinforce damaged areas," says Kang.
The method developed is simple and inexpensive. Kang hopes that these materials could be used to help with bone fractures or with dental issues. The team’s findings are reported in Advanced Materials.