Researchers in Japan have made brittle silicon stretchable by etching microscopic spiral springs into it, creating a material whose response to terahertz waves can be tuned by pulling it. The work, reported on 27 October 2026, came from the Osaka Research Institute of Industrial Science and Technology with the University of Osaka and Tohoku University, and was published in the journal Optica.

How stretching changes the material

Using microelectromechanical systems fabrication, the team etched spiral-shaped gaps through a silicon wafer 200 micrometres thick, forming spring arms about 10 micrometres wide. The resulting structure is self-supporting and needs no polymer or metal backing. When it is stretched, the gaps between the silicon arms widen, increasing the proportion of air and reducing the material's effective refractive index, which changes how terahertz waves pass through it.

Stretching the pattern by 12.6% reduced the refractive index by about 6% for one polarisation and 8% for the other, showing that deformation can tune the material's birefringence. The researchers said mechanical deformation opens a new route toward tunable terahertz circuits built with MEMS technology. Terahertz waves sit between microwaves and light, and are discussed in the reports for material inspection and future wireless communication, rather than as a finished product.

Sources: Phys.org and Nanowerk.