Russian scientists have patented a technology for creating nature-like materials with programmable properties by 3D printing. The new technique makes it possible to obtain structures that mimic the living bone or cartilage tissue of the human body. On the basis of their developments, scientists intend to produce substitutes for intervertebral discs and other implants. Their serial production can begin in 2025. Experts noted the promising technology for creating materials of the future.
Cellular structures
Scientists of the MISIS University of Science and Technology have patented a new method of manufacturing products from biosimilar materials with auxetic properties. Auxetics are substances that have unusual physical qualities. For example, when stretched, they do not become thinner, like ordinary materials, but thicker. And when compressed, they do not decrease, but increase.
This is due to the special shape of the structures they consist of. Usually auxetics contain concave elements, which provide unusual physical qualities. From the Greek language, the term translates as “that which tends to increase.”
Scientists expect to use their developments primarily to create substitutes for bone and cartilage tissues of the human body.
Due to their features, auxetic materials demonstrate a number of useful mechanical properties. In particular, they can absorb external pressure. They also resist destruction well and withstand multiple cyclic loads. In the human body, blood vessels and tubular bones can serve as samples of auxetics.
Currently, many methods of obtaining auxetics have been developed. However, modern computing technologies and 3D printing have revolutionized this field. With their help, scientists were able to develop and produce a lot of various structures with auxetic properties.
The research of Moscow scientists also lies in this area. The peculiarity of their development lies in the fact that they have learned to “program” the properties of auxetics in advance in accordance with the tasks set.
— The properties of materials depend on their internal structure. For example, the size of the pores and the thickness of the ribs between them. Our approach allows us to design new materials from geometrically correct cells. For example, by adjusting the sharpness of the angle between the edges of the cells, we can obtain the required characteristics,” said Vladislav Lvov, co-author of the development, engineer of the Scientific and Educational Center for Biomedical Engineering at NUST MISIS.
Vertebrate keiji
The process of creating a material consists of several stages. First, the necessary parameters for porosity and pore size are set in a special program, then the optimal size and shape of the cell is calculated. In particular, the possibilities of additive technologies are taken into account. Then the entire volume that needs to be filled is “built up” with cells. After that, the designed model structure is sent for 3D printing.
— Experiments have shown that printed cells in which the angles between the edges are smaller than the right angle (auxetic materials) they have higher statistical compressive strength and fatigue strength than cells based on structures with an angle of inclination of more than 90 degrees (cellular structures), — Vladislav Lvov noted.
Scientists saw the most promising direction for the application of their developments in the creation of nature-like materials. In particular, they have developed a technology for the production of 3D-printed vertebral cages — artificial implants that are used to completely or partially replace the intervertebral disc. They function as shock absorbers under various loads experienced by the spine, and provide its flexibility. Keiji is used when there is a herniated disc or when it is thinning due to age.
— During the operation, the damaged area of the intervertebral disc is removed and a cage is put in its place. This is, in fact, a minidomcrat whose task is to maintain the height of the spine. Most often, keiji are made of metals or polymers,” Vladislav Lvov explained.
The specialist explained: it is important to make sure that the mechanical properties of the cage material and the bones that it connects match each other. If the material is too hard, the vertebra will crumble, and if it is too loose, the cage itself will collapse. As a result, a new surgical intervention will be required.
— The use of auxetics makes it possible to solve this problem, since by their structure they mimic the native, that is, the native bone tissue of the body, — said the scientist.
Materials of the Future
Vladislav Lvov noted that the experimental samples of vertebrate cages with auxetic structure, made of titanium alloy, showed high strength and endurance during testing.
— The use of auxetic materials is not a new technology. But modern additive and computational methods have given it a rebirth. Including in the field of personalized medicine,” said Vadim Manukovsky, Honored Doctor of Russia, Director of the St. Petersburg Research Institute of Emergency Medicine.
On the basis of auxetics, it is possible to create medical fixators that will ideally cover individual parts of the human body, repeating their individual characteristics. For example, a broken finger, lower back or neck, the expert explained.
— If scientists develop technologies to create auxetics with programmable properties, this will open up broad prospects for them in creating materials of the future, — the engineer-inventor, general designer of the engineering company Unitsky String Technologies Inc. told Izvestia. Anatoly Yunitskiy.
He suggested that such materials would be in demand in the skin of spacecraft. Thanks to their properties, they will be able to absorb the impact energy of a micrometeorite or space debris and save expensive equipment. In the same capacity, auxetics will be useful when creating alien stations. In the field of medicine, on the basis of auxetics, it is possible to create dressings that distribute medicines proportionally. In general, the range of their application in various spheres of our life may soon be very wide, the specialist believes.
— Research in the field of development of new biomedical materials, specialists of the Research Scientific and Educational Center of Biomedical Engineering are carried out within the framework of the federal program “Priority-2030″. At the same time, the creation of a line of spinal cages that will be able to return thousands of people to normal life is one of the key directions,” said Alevtina Chernikova, Rector of MISIS University.
The head stressed that the industrial production of these products will be launched at one of the partner production sites in 2025.
In the future, scientists intend to continue developing biosimilar implants based on auxetic materials for other parts of the human body.
A source: https://e-cis.info/news/569/111668/
