Aerogels could be key to future terahertz technology

High-frequency terahertz waves have great potential in many applications, including next-generation medical imaging and communications.Researchers from Sweden’s Limping University showed in a study published in the journal advanced science, the transmission of terahertz light through aerogels made of cellulose and conducting polymers is tunable. This is an important step toward unlocking more applications for terahertz waves.

The terahertz range covers wavelengths on the electromagnetic spectrum between microwave and infrared light. It occurs very frequently. Therefore, many researchers believe that the terahertz range has great potential for applications in areas such as space exploration, security technology, and communication systems.

It could also be an interesting alternative to X-rays in medical imaging, since the waves can pass through most non-conductive materials without damaging any tissue.

However, there are some technical obstacles that need to be overcome before terahertz signals can be widely used. For example, it is difficult to generate terahertz radiation in an efficient manner, requiring materials that can receive and modulate the transmission of terahertz waves.

Researchers at Limping University have now developed a material whose absorption of terahertz signals can be turned on and off through redox reactions. The material is aerogel, one of the lightest solid materials in the world.

“It’s like a tunable filter for terahertz light. In one state, the electromagnetic signal is not absorbed, but in another state it is. This property is very useful for long-range signals or radar signals from space ,” Chen Shangzhi said. Postdoctoral fellow in the Organic Electronics Laboratory of Lianping University.

Linkping researchers used a conductive polymer, PEDOT:PSS, and cellulose to create the aerogels. They also designed the aerogels with outdoor applications in mind. It is both waterproof (hydrophobic) and defrosts naturally through heating by sunlight.

Conductive polymers offer many advantages over other materials used to create tunable materials. In addition to this, they are biocompatible, durable, and highly adaptable. Tunability comes from the ability to change the charge density in the material. The huge advantage of cellulose is that it is relatively cheap to produce compared to other similar materials, and it is a renewable material, which is key to sustainable applications.

“The transmission of terahertz waves in a wide frequency range can be adjusted between 13% and 91%, which is a very large modulation range,” said LOE postdoc Chaoyang Kuang.