Silk-Based Material Could Power Future 6G Networks

A transparent composite made from recycled silk can manipulate terahertz light frequencies, the range expected to underpin 6G networks. This discovery, published in Nature Sustainability, comes from a collaboration between Imperial College London and the University of Michigan College of Engineering.

The material's properties rival plastic while retaining silk's natural structure. It is lighter than most metals and stronger than many petroleum-based polymers. In tests, its mechanical strength matched carbon-fiber-reinforced polymers used in aviation and automotive manufacturing. The composite is also biocompatible; when implanted in mice, it gradually degraded, suggesting potential for temporary medical implants.

Controlling Light Polarization

The core breakthrough involves the material's interaction with terahertz radiation, a range considered vital for future communication systems like 6G, which could transmit data hundreds of times faster than 5G. The silk composite can alter light's polarization—the direction of an electromagnetic wave's oscillation—creating an additional channel for encoding information. This ability is rare in transparent materials.

Nick Kotov, a professor of chemistry and engineering at the University of Michigan, explained the challenge:

"It's difficult to create a material with terahertz optical activity that can rotate light and still be practically transparent. This composite is unique because it can do this at the frequencies needed for many future technologies. Typically, such biomaterials absorb terahertz light very strongly, so very little light comes out."

Preserving Fiber Structure

The material's unique properties stem from silk's internal organization. Its molecular structure combines ordered crystalline regions with amorphous, less structured zones, providing both strength and flexibility. Co-author Chunmei Li noted:

"For such a flexible material, it is surprisingly strong. Through processing, we can surpass the capabilities of many other biomaterials."

Unlike previous methods, the new technique does not dissolve the silk but physically compresses it. Fibers are heated to 125–215°C under pressures of 1,900–9,800 atmospheres. Water is removed, and the structure fuses into a single sheet while preserving key crystalline elements.

Eco-Friendly Processing

A secondary goal of the work is reducing textile waste. Instead of dissolving silk in chemical reagents and turning it into powder, the researchers applied a gentler approach. Emiliano Bilotti of Imperial College London explained:

"Silk's remarkable properties come from its hierarchical microstructure. We wanted to preserve as much of the pristine fibers as possible."

The process can be technologically simple: boiling removes sericin, the natural protein binding the fibers, after which the material is pressed into sheets.

Future Applications

The team is currently assessing the technology's scalability and potential integration into sensors, optical elements, and telecommunications components. A life-cycle analysis is underway to evaluate the approach's true environmental efficiency. If scalability is confirmed, recycled silk could find use in 6G devices, lightweight structural components, packaging, and biomedical implants.