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Silk sensor detects damage in composites
Tuesday, 04 July 2017

MARYLAND – Researchers at the National Institute of Standards and Technology (NIST) in the United States have developed a new sensor made of silk that detects damage to composite materials during its manufacture. NIST says that the new process facilitates the design of strong and better composites before they come off the production line.

The NIST project claims to have developed a way of embedding a nanoscale damage-sensing probe made of ebony and silk, into a lightweight composite, in order to detect damage to composites in the manufacturing process. The probe, called a mechanophore, is made from the dye, rhodamine spirolactam, which reacts to applied force and exposes damage to composites during their manufacturing process.

Researchers fixed the dye to silk fibres, inside an epoxy-based composite, then applied progressive amounts of force to the material, stress-activating the dye, which showed imperfections in the composite. NIST said it has also developed a specific red laser and microscope to take photos of the composite under a black light to detect the dye. Photos can show fractures in the interior of the material, with the tiniest amount of damage now available to view.

The research at NIST was led by Jeffrey Gilman, who said: “The sensor solves a long-time problem in the development of composites and provides a way forward for designers of these materials to optimise them for various applications. There have long been ways to measure the macroscopic properties of composites. But for decades the challenge has been to determine what was happening inside, at the interface”.

Designers have previously wrestled with the problem of a material’s durability and its ability to withstand force until now, NIST says. Practical applications for the sensor includes fuel-efficient vehicles and bridges.

Gilman says NIST also plans to expand its composites research to explore the sensor’s applications in various composites, and how look at they can withstand cold and heat. Composites that can perform with prolonged exposure to water are in high demand for use on bridges and wind turbines, according to the research conducted by NIST.

This research was published in the Advanced Materials Interfaces journal and can be found: here.