A reactive cone prepared from the new active textile. Image: Pedro Silva/Aalto University.
A reactive cone prepared from the new active textile. Image: Pedro Silva/Aalto University.

New textiles developed by researchers at Aalto University in Finland change shape when they heat up, giving designers a wide range of new options. In addition to offering adjustable aesthetics, such responsive smart fabrics could also help to monitor people’s health, improve thermal insulation, and provide new tools for managing room acoustics and interior design.

The new fabrics weave together old technology and a new approach. Liquid crystalline elastomers (LCEs) were developed in the 1980s. They are a smart material that can respond to heat, light or other stimuli, and they’ve been used as thin films in soft robotics. Although LCEs have been made into fibres, they hadn’t previously been made into textiles.

In collaboration with researchers at the University of Cambridge in the UK, a team from the Multifunctional Materials Design research group at Aalto University, led by Jaana Vapaavuori, has now used LCE yarns to make woven fabrics using conventional textile crafting techniques, and tested how they behave. The researchers report this work in a paper in Advanced Materials.

The team wove LCE yarn in different patterns to make plain fabric, satin, twill and a weft rib fabric. They made two versions of each pattern using either a soft or stiff LCE yarn, and then they tested how the different fabrics responded to heat from an infrared lamp.

All of the LCE fabrics contracted as they warmed up, though the exact response differed from pattern to pattern. The changes were reversible – the patterns relaxed back to their original shape as their temperature dropped.

“At first, the impact of using industrial textile techniques with these kinds of new materials wasn’t clear to us,” says Pedro Silva, a postdoctoral researcher at Aalto University who led the study. “The elasticity of the two types of LCE yarn is comparable to spandex or even softer. That meant it was essential to understand if the textile industry could use these yarns and how the combination with conventional yarns would impact their movement.”

Next, the team combined LCE yarns with linen and nylon in a radial pattern to weave a circle that would lift itself into a cone when heated. Heating the pattern caused the LCE yarn to contract, pulling the cloth up into a cone. As it cooled, the cone relaxed back into a flat circle.

This proof-of-concept brings smart, reactive textiles one step closer to reality. “From day one of this project, we took on the challenge of working with experts spanning different disciplines at two institutes,” says Maija Vaara, a PhD student at Aalto University who crafted the weaves and laces. “The research succeeded and benefited tremendously from this multidisciplinarity, and now the results are openly available. We hope our work will trigger new ways of thinking when it comes to the materials of tomorrow.”

This story is adapted from material from Aalto University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.