Polar bears can survive in the extremely cold Arctic, and their thick hair and subcutaneous fat play a vital role. Recently, inspired by this, Zhejiang University scholars developed a bionic fiber, which successfully made a rabbit realize "thermal stealth". Different from "optical stealth", "thermal stealth" refers to the stealth effect achieved because infrared thermal imaging equipment can not identify the heat emitted by organisms. The results of this research are also expected to make people wear warmer clothes and even let soldiers wear "stealth uniforms."
According to American media reports on February 21st, Professor Bai Hao from the School of Chemical Engineering and Biological Engineering of Zhejiang University led his team to imitate the hair structure of polar bears and developed an orderly and porous thermal insulation fabric. This kind of fabric is not only very warm, but also has the special function of "invisibility".
professor Bai Hao of Zhejiang university? Xinhua video screenshot
It is understood that under the microscope, polar bear hair is a transparent hollow porous structure, which is an excellent thermal insulation fiber. Not only that, their hair can reflect infrared radiation, making polar bears almost invisible in thermal imaging cameras.
in order to imitate this structure, Bai Hao team dissolved silk in water to make a spinning solution with a water content of 95%. After that, the mixture was slowly injected into a cryogenic device with a syringe to form frozen porous fibers with a diameter of about 2 microns and containing ice crystals. Finally, through freeze-drying, the ice crystals in the fiber sublimate, leaving many ordered lamellar holes.
They covered the woven fabric on a rabbit and observed it with a thermal imaging camera. The results show that the camera can hardly detect the heat of rabbits in the environment of -1℃ to 4℃.
The rabbit's body can be "invisible" in the infrared thermal imaging camera
It is reported that Sylvain Deville, a scientist from Cavaillon, has used the same ice template method to make porous fibers. However, De Ville believes that Zhejiang University has demonstrated a stronger ability to control the fiber structure.
In the research, Bai Hao's team also added carbon nanotubes to bionic fibers to create a new electric heating fabric. Under the voltage of 5 volts, the electrically heated fabric can automatically rise from 24℃ to 36℃ within one minute. Although the heated fabric no longer has the "thermal stealth" effect, it has become a "winter dress" with better warmth retention effect.
Bai Hao has also obtained a patent for this frozen spinning technology, and he hopes to develop this fabric into a commodity. Moreover, he is also very optimistic about his achievements in the fields of industry and military. "If you use it to produce military uniforms, you can hide the traces of soldiers."
However, De Ville believes that Bohol's goal may not be achieved in the short term. "With the current technology, the process of producing a fabric is too time-consuming to reach the level of mass production."
It is reported that the next research direction of Bai Hao's team is to improve the strength of this bionic material and integrate it with more materials to expand new functions.