This photo shows researchers measuring the electrical conductivity of a knitted textile actuator. Photo: Thor Balkhed/Linköping University.
This photo shows researchers measuring the electrical conductivity of a knitted textile actuator. Photo: Thor Balkhed/Linköping University.

By coating a normal fabric with an electroactive material, researchers have given it the ability to actuate in the same way as muscle fibers. This opens new opportunities for designing ‘textile muscles’ that could, for example, be incorporated into clothes, making it easier for people with disabilities to move. The study, which was carried out by researchers at Linköping University and the University of Borås in Sweden, is reported in a paper in Science Advances.

Developments in robot technology and prostheses have been rapid, due to recent technological breakthroughs. For example, devices known as ‘exoskeletons’ that act as an external skeleton and muscles have been developed to reinforce a person's own mobility.

"Enormous and impressive advances have been made in the development of exoskeletons, which now enable people with disabilities to walk again," says Edwin Jager, associate professor in the Division of Sensor and Actuator Systems at Linköping University. "But the existing technology looks like rigid robotic suits. It is our dream to create exoskeletons that are similar to items of clothing, such as ‘running tights’ that you can wear under your normal clothes. Such device could make it easier for older persons and those with impaired mobility to walk."

Current exoskeletons are driven by motors or pressurized air. In the new study, the researchers have taken advantage of lightweight and flexible fabrics to develop what can be described as ‘textile muscles’. The researchers took a mass-produced fabric and coated it with an electroactive material, which provides the force to power the textile muscle. Applying a low voltage to the fabric causes the electroactive material to change volume, which in turn causes the yarn or fibers to increase in length. The exact properties of the textile can then be controlled by its woven or knitted structure.

"If we weave the fabric, for example, we can design it to produce a high force. In this case, the extension of the fabric is the same as that of the individual threads," explains Nils-Krister Persson, associate professor in the Smart Textiles Initiative at the Swedish School of Textiles, University of Borås. "But what happens is that the force developed is much higher when the threads are connected in parallel in the weave. This is the same as in our muscles. Alternatively, we can use an extremely stretchable knitted structure in order to increase the effective extension."

In the paper, the researchers show that the textile muscles can be used in a simple robot device to lift a small weight. They demonstrate that the technology can lead to new ways of designing and manufacturing devices known as ‘actuators’, which – like motors and biological muscles – can exert a force.

"Our approach may make it possible in the long term to manufacture actuators in a simple way and hopefully at a reasonable cost by using already existing textile production technologies. What's more interesting, however, is that it may open completely new applications in the future, such as integrating textile muscles into items of clothing," says Jager.

This story is adapted from material from Linköping 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.