Light-Activated Metal Structures Morph Without Coatings
Researchers have developed a light-responsive metal structure that can change shape and rise from a flat surface without needing a separate light-absorbing coating, opening doors for new interfaces and soft robots.
Mechanical engineers at KAIST have created a novel shape-memory alloy (SMA) structure that transforms into a three-dimensional form when exposed to light, eliminating the need for external light-absorbing coatings. This development utilizes a single UV laser process to create a "photothermally driven meta-morphing structure" from a flat NiTi SMA sheet.
The technology draws inspiration from kirigami, an art form involving cutting and folding paper to create 3D shapes. Researchers precisely cut and fold a metal sheet to achieve a predetermined 3D form. Shape-memory alloys, known for their lightweight nature and ability to generate significant force, are ideal for applications like soft robots and wearable actuators, as they return to a programmed shape when heated.
A key challenge with previous photothermal SMA actuators was the NiTi alloy's inefficient absorption of near-infrared light. This often required additional coatings like graphene oxide or TiN films, which could detach over time, add weight, and slow response times. The KAIST team overcame this by using UV laser micromachining to create kirigami patterns and simultaneously form a micro-nano porous titanium oxide layer on the surface through laser-induced oxidation.
This integrated process significantly enhances near-infrared light absorption without external additions. The team also demonstrated control over deformation height and force by adjusting structural parameters. Furthermore, they achieved "spatiotemporal actuation control," allowing different regions to deform sequentially by spatially controlling the laser-induced oxidation, essentially encoding deformation order and timing directly into the material's light-absorption properties.
To showcase the potential applications, the researchers integrated these photothermal SMA metastructures with a multichannel near-infrared LED array. This enabled the creation of 3D shape displays and haptic interfaces, successfully forming the letters "KAIST" and displaying directional tactile navigation signals. The developed laser programming technology is described as a manufacturing-friendly platform that encodes both mechanical deformation and optical properties into a single metallic structure, with broad applications for light-controlled morphing interfaces.
This development represents a significant advancement in photothermal actuation by eliminating the need for separate coatings on shape-memory alloys. By integrating light absorption and mechanical design through UV laser micromachining and kirigami principles, the researchers have created a more robust and efficient morphing structure. This monolithic approach is highly relevant for creating lightweight, wirelessly controlled actuators for soft robotics, wearable devices, and adaptive interfaces, potentially simplifying manufacturing and improving performance.
Edited by the news editor with AI from the original report — please refer to the original source.