High-frequency terahertz waves have great potential to replace X-ray examinations in the future and be used in space research, among other things. Researchers at Linköping University found, in a study published in Advanced sciencedemonstrated that the transmittance of terahertz radiation could be controlled by an airgel made of cellulose and a conductive polymer. An important feature to be able to unlock more uses for terahertz waves.
The terahertz range is the wavelengths that fall between microwaves and infrared on the electromagnetic spectrum and have a very high frequency. Thanks to this, many researchers believe that terahertz waves have great potential for use, among other things, in space research, security technology and communications systems. In medical imaging, it can be an interesting alternative to X-ray examinations as the waves can pass through most non-conductive materials without damaging any tissue.
But there are a number of technological hurdles before terahertz signals can be widely used. Among other things, terahertz radiation is difficult to produce efficiently. Materials that can receive and control the transmittance of terahertz waves are also needed.
Now researchers at Linköping University have done just that They developed a material that can turn on and off the absorption of terahertz signals through a redox reaction. The material is airgel, one of the lightest solid materials in the world.
– It acts as an adjustable filter for terahertz waves. In one position, the electromagnetic signal will not be absorbed, and in the other position it can be absorbed. This property could be useful for long-range signals, such as space or radar signals, says Shanji Chen, a postdoctoral fellow at the Laboratory of Organic Electronics, LOE, at Linkoping University.
The researchers at Linköping used a conductive polymer, PEDOT:PSS, and cellulose to create their airgel. They also designed the airgel with outdoor applications in mind. It is hydrophobic (hydrophobic) and can be frozen with the help of the heat of the sun.
Conductive polymers have many advantages Compared to other materials used to create modifiable materials. Among other things, they are biocompatible, durable and have great adaptability. Controllability comes from the ability to change the charge density in the material. The big advantage of cellulose is its relatively cheap production cost compared to other similar materials and that it is a renewable material, which is key to sustainable applications.
“The transmittance of terahertz waves can be regulated within a wide frequency range between about 13% and 91% with our material, which is very high tunability,” says Zhaoyang Kuang, a postdoctoral researcher at LOE.
The study was funded, among others, by the Swedish Research Council, the Strategic Research Foundation, the Foundation for the Internationalization of Higher Education and Research, the Knut and Alice Wallenberg Foundation, the Wallenberg Center for Wood Science and through the Strategic Program of the Swedish Government. Investment in new functional materials, AFM, at Linköping University.
Article: Broadband switchable terahertz absorbers based on a cellulose polymer airgel procedure; Zhaoyang Kuang, Shangzi Chen, Min Luo, Qilun Zhang, Xiao Sun, Shaobo Han, Qingqing Wang, Valery Stanishev, Vanya Darakcheva, Referrant Crespin, Mats Fahlmann, Dan Zhao, Qi Wen, Magnus B. Johnson; Advanced sciencepublished online November 23, 2023. DOI: 10.1002/advs.202305898
facts: The terahertz range is the wavelengths that fall between microwaves and infrared on the electromagnetic spectrum. The waves range in width from 0.1 to 1 millimeter, and their frequency is as low as 0.3 terahertz and as high as 30 terahertz. 1 terahertz means that 1,000 billion waves are transmitted or received in one second.
communication
Shanji Chen, postdoctoral fellow, [email protected], 011-36 34 90
Chaoyang Kuang, postdoctoral fellow, [email protected], 011-36 34 67
Magnus Johnson, Professor, [email protected], 011-36 34 03
The press release he sent:
Anders Tornholm
Media communication, Linköping University
013-28 68 39
[email protected]
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