Bandage-kirigami
At MIT, they came up with kirigami-a bandage that repeats the bends of the joints and does not fall off
Maxim Agadzhanov, Geektimes
It is very difficult to put a bandage on the elbow and knee joints. Even if you do everything right, after a few cycles of flexion-extension, the bandage slides. In addition, ordinary fabric of any type causes certain inconveniences to the skin after a few hours. Now MIT engineers have tried to find a new solution, and they seem to have succeeded.
The basis of this solution is kirigami, the Japanese art of making figurines with scissors. In origami, paper is only folded without using a knife or scissors. So, MIT has developed a new type of bandage, which, thanks to incisions on the surface, can withstand more than 100 cycles of flexion-extension. The secret is the location of the longitudinal sections relative to each other.
The researchers attached a "kirigami film" to the knee of a volunteer and found that every time the knee is bent, the usual film does not withstand the load well. But the "kirigami film" copes with this perfectly, withstanding not only stretching, but also compression. In order to show the potential of the film, the group created a real bandage. A variety of miniature sensors can be fixed on its surface, which can be useful both in sports and in hospitals.
According to the developers, the idea of using kirigami when creating this kind of bandages expands the possibilities of their use. "Now, if we talk about electronics, people attach devices to places with a slight deformation. But where the deformation is stronger, usually nothing is placed. I think kirigami is a solution that allows you to use wearable electronics even where it has not been used before," said Ryuke Jiao, a representative of the development team.
The scientists published the results of their work in the authoritative medical publication Soft Matter (Zhaoet al., Kirigami enhances film adhesion).
Work began on the creation of the kirigami film in August 2016. Then the team of researchers received a task from Chinese colleagues to create an improved version of a pain-relieving bandage. A Chinese company produced and sold such bandages, but was not too happy with their limited functionality.
"They are quite widespread, especially in China, but if you try to fix them on the elbow or knee joints, the bandage will very quickly cease to perform its functions and simply fall off," say the developers of the flexible bandage. "This is a huge problem for the company, and she asked to solve it."
Almost from the very beginning, the developers decided to try kirigami as a potential solution to the problem. The art of kirigami has been developing for several centuries, and allows you to create the most complex shapes from paper, which cannot be done using origami in any way. It was decided to take this idea as a basis. As it turned out, kirigami improves not only the flexibility of the source material, but also allows it to be better fixed on the surface of the arm or leg.
Test versions of the bandage were printed on a 3D printer, which made it possible to create a bandage of any shape and almost any size. The film can be made from both conventional polymers and metal. Specialists conducted tests with bending, stretching and compression of the material. It turned out that the bending of the "kirigami film" withstands much better than usual.
After many tests, scientists have found an almost ideal option for a bandage. Scientists have already filed a patent application, which is under consideration. They also continue to cooperate with the Chinese company, from whose assignment the project started. According to representatives of the company, in the same China, bandages that relieve pain (for example, from stretching) are very popular, so the authors of the idea hope to popularize the development.
The development itself may not seem too significant compared, for example, with bionic prostheses. But the benefit of the "kirigami film" is that it is made of a special polymer that can also be used to inject drugs into the human body through the skin. Bandages can be of any shape, and they can be used for a wide range of tasks in different fields – from sports, to, as already mentioned, medical.
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