NUS researchers innovate scalable robotic fibres with light-emitting, self-healing and magnetic properties

A team of interdisciplinary scientists from the Department of Materials Science and Engineering under the College of Design and Engineering at the National University of Singapore (NUS) has developed flexible fibres with self-healing, light-emitting and magnetic properties.

The Scalable Hydrogel-clad Ionotronic Nickel-core Electroluminescent (SHINE) fibre is bendable, emits highly visible light, and can automatically repair itself after being cut, regaining nearly 100 per cent of its original brightness. In addition, the fibre can be powered wirelessly and manipulated physically using magnetic forces.

With multiple useful features incorporated into a single device, the fibre finds potential applications as light-emitting soft robotic fibres and interactive displays. It can also be woven into smart textiles.

The team's research, conducted in collaboration with the Institute for Health Innovation & Technology (iHealthtech) at NUS, was published in Nature Communications on 3 December 2024.

Light-emitting fibres have become an area of burgeoning interest owing to their potential to complement existing technologies in multiple domains, including soft robotics, wearable electronics and smart textiles. For instance, providing functionalities like dynamic lighting, interactive displays and optical signalling, all while offering flexibility and adaptability, could improve human-robot interactions by making them more responsive and intuitive.

However, the use of such fibres is often limited by physical fragility and the difficulty of integrating multiple features into one single device without adding complexity or increasing energy demands.

The NUS research team's SHINE fibre addresses these challenges by combining light emission, self-healing and magnetic actuation in a single, scalable device. In contrast to existing light-emitting fibres on the market, which cannot self-repair after damage or be physically manipulated, the SHINE fibre offers a more efficient, durable and versatile alternative.

The fibre is based on a coaxial design combining a nickel core for magnetic responsiveness, a zinc sulphide-based electroluminescent layer for light emission and a hydrogel electrode for transparency. Using a scalable ion-induced gelation process, the team fabricated fibres up to 5.5 metres long that retained functionality even after nearly a year of open-air storage.

The fibre's hydrogel layer self-heals through chemical bond reformation under ambient conditions, while the nickel core and electroluminescent layer restore structural and functional integrity through heat-induced dipole interactions at 50 degrees Celsius.

The SHINE fibre can be knitted or woven into smart textiles that emit light and easily self-heal after being cut, adding an element of durability and functionality to wearable technology. With its intrinsic magnetic actuation, the fibre itself can also function as a soft robot, capable of emitting light, self-healing, navigating confined spaces and signalling optically even after being completely severed. Additionally, the fibre can be used in interactive displays, where its magnetism allows for dynamic pattern changes that facilitate optical interaction and signalling in the dark.