Materials

Electric Coating Turns Fabrics Into Soft Exoskeletons

New "textile muscles" could assist laborers, the elderly or people with disabilities.

<p>Thor Balkhed/Linköping University</p>

In the future, we may need a whole new definition for the muscle shirt.

Researchers in Sweden have developed an electroactive "textile muscle" system that turns apparel fabrics into external, artificial musculature. The technology could power a new kind of soft exoskeleton solution for laborers, people with disabilities or anyone who needs a little extra when pulling and lifting.

It works like this: Lightweight apparel fabric is coated with an electroactive material in a process similar to dyeing. After the material dries, any low voltage current applied to the fabric - by way of a wearable battery, say - changes the shape of the fabric and produces force in a designated direction or configuration. As the individual threads change volume, the particular pattern or weave in the fabric amplifies and directs movement.

It's essentially the same kind of mechanical action that powers our own muscles, according to the researchers at Linköping University and the University of Borås in Sweden. Similar soft exosuit systems have been developed, but the Swedish technology is designed to be used with mass-producible fabrics, the typical cotton or synthetic materials used to make clothing worldwide.

"We envision these actuators to be integrated in items of clothing," co-author Edwin Jager told Seeker.

A close-up photograph of a knitted textile actuator (or textile muscle) showing the individual loops. | Thor Balkhed/Linköping University

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One immediate question arises: Just as our organic muscles are anchored to our bones, wouldn't the textile muscles need to be pull against some kind of rigid structure?

"Indeed, there would be a need to somehow attach the actuators to the body," said Jager, associate professor at the Division of Sensor and Actuator Systems at Linköping University. "This could be in the form of a tight elastic 'sleeve,' similar to the ones currently used to give support for injured joints, like the knee and elbows sleeves or pads you can buy at pharmacies or sport shops."

Jager and his team are also investigating solutions in which the artificial muscles could pull against Velcro bands wrapped around the limb on both sides of a joint.

"Such rigid elements or structures, where needed, can be integrated in the textile using a fully automated process and employing lightweight materials," Jager said.

Measuring the electrical conductivity of a knitted textile actuator. | Thor Balkhed/Linköping University

To test the possibilities of the new technology, the researchers wrapped a sample of their textile actuator (or "textuator") around a lever arm made from Scandinavia's great gift to humankind - Legos. The textuator was able to move the arm and lift a two-gram weight.

As a next step, the research team hopes to make specific adjustments to the fabric and the polymer coating to design a soft exoskeleton suit to assist with walking.

"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," Jager said in press materials accompanying publication of the research. "Such devices could make it easier for older persons and those with impaired mobility to walk."

The research was published today in the journal Science Advances.

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