From the Sector

Smart textiles have the potential to revolutionise healthcare. In his doctoral thesis in textile technology at the University of Borås, Emanuel Gunnarsson presents unique solutions to the bottleneck that has long inhibited the market.

With an ageing population, increasing demands are being placed on healthcare and smart textiles can offer a solution where only imagination sets limits. “The long-term goal of most smart textiles is for them to be so easy to use that the user doesn't think of them as anything more than regular garments. No special procedure should be needed to use them. If we succeed in that, we won't burden healthcare by having healthcare personnel administer vital parameter monitoring such as blood pressure and pulse, as the user can handle it themselves,” said Emanuel Gunnarsson.

In his work, he has investigated how a t-shirt for measuring heart rhythm and movement patterns, and garments for electrostimulation, can be produced in a single step. This involves the connection between the contact surfaces (electrodes), the insulated conductive paths between the electrode and the contact point, and the electrical measuring equipment required.

“This, as far as we know, has never been described before. We are completely convinced that this is the solution to a significant bottleneck when it comes to getting the smart textile market going in earnest,” said Emanuel Gunnarsson.

His work has resulted in two different simple ways to produce smart textiles. He demonstrates that sensors can be integrated using standard textile manufacturing methods. The research also includes criticism of some of the methods used to measure the functionality of smart textiles, and advice on how to do it better instead.

“The next natural step will be to see how these garments cope with one of the toughest challenges a garment faces, namely washing. Especially as these garments must be worn closest to the skin, they will need to be washed relatively often,” said Emanuel Gunnarsson.

Studies from other universities indicate that the yarns used to measure signals from the body do not withstand many washes, but after a small pilot study, Emanuel Gunnarsson is hopeful of the opposite.

Electronically conductive fibres are already in use in smart textiles, but in a recently published research article, ionically conductive fibres have proven to be of increasing interest. The so-called ionofibres achieve higher flexibility and durability and match the type of conduction our body uses. In the future, they may be used for such items as textile batteries, textile displays, and textile muscles.

The research project is being carried out by doctoral student Claude Huniade at the University of Borås and is a track within a larger project, Weafing, the goal of which is to develop novel, unprecedented garments for haptic stimulation comprising flexible and wearable textile actuators and sensors.

In Claude Huniade’s project, the goal is to produce conductive yarns without conductive metals.
"My research is about producing electrically conductive textile fibres, and ultimately yarns, by coating non-metals sustainably on commercial yarns. The biggest challenge is in the balance between keeping the textile properties and adding the conductive feature," said Claude Huniade.

Currenty, the uniqueness of his research leans towards the strategies employed when coating. These strategies expand to the processes and the materials used.

Uses ionic liquid
One of the tracks he investigates is about a new kind of material as textile coating, ionic liquids in combination with commercial textile fibres. Just like salt water, they conduct electricity but without water. Ionic liquid is a more stable electrolyte than salt water as nothing evaporates.

"The processable aspect is an important requirement since textile manufacturing can be harsh on textile fibres, especially when upscaling their use. The fibres can also be manufactured into woven or knitted without damaging them mechanically while retaining their conductivity. Surprisingly, they were even smoother to process into fabrics than the commercial yarns they are made from," explained Claude Huniade.

Ionofibres could be used as sensors since ionic liquids are sensitive to their environment. For example, humidity change can be sensed by the ionofibers, but also any stretch or pressure they are subjected to.

"Ionofibres could truly shine when they are combined with other materials or devices that require electrolytes. Ionofibres enable certain phenomena currently limited to happen in liquids to be feasible in air in a lightweight fashion. The applications are multiple and unique, for example for textile batteries, textile displays or textile muscles," said Claude Huniade.

Needs further research
Yet more research is needed to combine the ionofibres with other functional fibres and to produce the unique textile devices.

How do they stand out compared to common electronically conductive fibres?
"In comparison to electronically conductive fibres, ionofibers are different in how they conduct electricity. They are less conductive, but they bring other properties that electronically conductive fibers often lack. Ionofibres achieve higher flexibility and durability and match the type of conduction that our body uses. They actually match better than electronically conductive fibres with how electricity is present in nature," he concluded.