Colour shows where it hurts: NTU sensor makes structural stress visible
A polymer from Singapore changes colour depending on the load – from cooler tones to red. It needs neither battery nor wiring and is meant to flag excessive stress on bridges and cables early.
Photo: SSMG-ITALY / Wikimedia Commons, CC BY-SA 3.0 (cropped and resized)
Video: YouTube · NTUsg · youtube.com
Researchers at Nanyang Technological University (NTU) in Singapore have developed a sensor that makes mechanical stress visible to the naked eye. The material is a smart polymer that takes on a different colour depending on the load: as stress rises, it shifts like a traffic light from cooler tones towards red. The study led by Assistant Professor Gun Kim and his PhD student Seungo Baek was published in the journal Advanced Science, and the School of Civil and Environmental Engineering presented it on 23 September. NTU has also released a video about it.
The sensor works without batteries, wiring or complex monitoring systems. The sensing function is built into a network of entangled polymer chains, so the material can serve as both a sensor and a structural component. It shows not only where stress is concentrated but also how severe it is. According to Baek, it can measure both strain and stress.
The technology is intended for bridges, cables and other critical infrastructure where excessive stress needs to be detected early. No training is needed to read the colour, Kim says. So far the material has been tested on individual samples; the team is working on scaling it up to full-size structural components.