Researchers Develop Flat Optical Fiber With 1,000x Greater Pressure Sensitivity

Researchers at Sweden's KTH Royal Institute of Technology and the UK's University of Southampton have constructed a flat, ribbon-shaped silica optical fiber that demonstrates up to 1,000 times higher pressure sensitivity than standard cylindrical fibers. The development, published in Nature Communications and first reported by TechXplore, introduces a high-aspect-ratio platform designed to transform how structural changes are measured in industrial hardware and energy systems.

Instead of mechanically flattening traditional round fibers post-fabrication, the team developed a manufacturing process that shapes the glass preform from the outset. Using laser-assisted glass processing, the researchers formed internal microstructures, including micro-scale air channels and specialized material inclusions, directly within the quadrilateral silica framework.

The flat structural profile allows the physical frame of the optical strand to function directly as a sensing element. In physical laboratory trials, the high-aspect-ratio design significantly magnified mechanical responses to pressure. The researchers also created a multi-parameter sensor variant by infusing sections of the internal cavities with a tin-based alloy, enabling the fiber to simultaneously measure localized temperature shifts alongside physical stress.

According to KTH researcher Pawel Maniewski, the accomplishment represents a fundamental evolution in photonics rather than a minor geometric variation. "This is not just a different-looking fiber," Maniewski noted, describing the technique as "a new design space for optical fiber." He added that "by changing the geometry, we can make the glass itself much more responsive to the physical world around it."

Because the ribbon-like fiber utilizes standard silica, it retains operational compatibility with conventional optical networks while offering key advantages over legacy electronic sensors. Optical sensing systems are immune to electromagnetic interference, possess minimal mass and volume, and can endure harsh, chemically aggressive, or high-temperature operating conditions that would degrade electronic micro-sensors.

The design offers immediate commercial potential across several advanced engineering sectors. Embedded inside lightweight composite materials, the flat fibers could provide real-time structural health monitoring for commercial aircraft, autonomous drones, and civil infrastructure. Additionally, integrating the sensors directly inside energy storage cells could track internal pressure and heat variations to catch battery malfunctions before thermal failures occur.

Looking forward, the research team aims to scale the technology for commercial integration. University of Southampton professor Chris Holmes emphasized that the milestone gives optical sensing "a new dimension," noting that the project's next phase will focus on transitioning the flat fiber platform from proof-of-concept testing to operational deployments across advanced composites, intelligent drones, and safer battery technologies.