Researchers Inspired by Human Bones, 3D Print Extremely Light, Strong Structures

Scientists often look towards biology, when they set out to find the most efficient way of doing something. Whether it’s photosynthesis as a means for energy conversion, or the human brain as a way to store and recall information, biology can be a great inspiration for new, more efficient technologies.

This seems to be the case, in a publication today by German researchers at the Karlsruhe Institute of Technology. They were seeking to find a material that was both light, but also strong, that could be 3D printed with current technology today. What in nature is light, but also extremely strong for it’s weight? The answer, human bones. Bones are constructed of thin calcium, phosphorus, and other mineral segments which form hollow connecting structures. This makes them light, which would usually mean weak, however the way the hollow structures within a bone connect in certain patterns, transfers weight evenly, making them extremely durable and resistant to a good deal of stress.

This inspiration led the researchers to use very precise lasers to 3D print tiny objects with the same type of repeating structures found in the bones of any human being. The researchers used a special polymer which they covered in an aluminum compound, for the material of the 3D printed structures. The objects are so small, that they had to use special 3D laser lithography in order to get accuracy down to one micron in diameter.  As you see in the image below of the final printed objects, they used several different patterns to test which ones would stand up to the most stress.

The research will likely be a major stepping stone for the development of stronger lighter materials within literally every industry imaginable. There is still more research to be done, but this is a tremendous accomplishment, and one which shows yet another way 3D printers could change the world we live in for the better.

The abstract for the research reads as follows:

To enhance the strength-to-weight ratio of a material, one may try to either improve the strength or lower the density, or both. The lightest solid materials have a density in the range of 1,000 kg/m3; only cellular materials, such as technical foams, can reach considerably lower values. However, compared with corresponding bulk materials, their specific strength generally is significantly lower. Cellular topologies may be divided into bending- and stretching-dominated ones. Technical foams are structured randomly and behave in a bending-dominated way, which is less weight efficient, with respect to strength, than stretching-dominated behavior, such as in regular braced frameworks. Cancellous bone and other natural cellular solids have an optimized architecture. Their basic material is structured hierarchically and consists of nanometer-size elements, providing a benefit from size effects in the material strength. Designing cellular materials with a specific microarchitecture would allow one to exploit the structural advantages of stretching-dominated constructions as well as size-dependent strengthening effects. In this paper, we demonstrate that such materials may be fabricated. Applying 3D laser lithography, we produced and characterized micro-truss and -shell structures made from alumina–polymer composite. Size-dependent strengthening of alumina shells has been observed, particularly when applied with a characteristic thickness below 100 nm. The presented artificial cellular materials reach compressive strengths up to 280 MPa with densities well below 1,000 kg/m3.

The entire research paper can be read at the following link:  https://www.pnas.org/content/early/2014/01/29/1315147111.full.pdf+html?sid=098a4176-77fb-4812-8ec0-01a0491c16dd

Discuss this research at 3DPrintboard: https://3dprintboard.com/showthread.php?1627-3D-Printing-Bone-Like-Structures-For-Strength-and-Weight