A new development based on the ability of plants being able to absorb water through their roots has inspired a textile membrane which promises to revolutionise garment thermal regulation.
The HYDRO_BOT technology, developed by Swiss company Osmotex, takes the principle of osmosis, where plants draw in moisture from the soil through their roots, and accelerates its effects through the use of electricity.
Due to this, the HYDRO_BOT membrane has the capability to rapidly wick sweat away from the human body and expel it on the other side. As such an efficient solution to sweat-wicking, the technology has the potential for use in ski gear solutions.
Engineered electronics
Due to the speed at which humans sweat, particularly when participating in physical activity, the development team had to find a solution to keep up. By applying a voltage of around 1.5 volts, they were able to speed up the membrane’s osmosis process.
The special polymer membrane is only 20 micrometres thick and is coated on both sides with a noble metal by means of plasma coating. According to Osmotex, this is achieved by using just under 0.2 grams of gold per ski jacket. While this has an impact on the price of the membrane compared to using silver, gold has been proven to be much more durable than silver-coated electrodes.
When the electrical voltage is applied to the membrane, salt ions and the liquid surrounding them transfer through the tiny pores in the membrane to the other side, thus taking them away from the body.
In order to complete the electrical circuit, a conventional battery, which can be switched on or off depending on the weather and the activity, is connected to the membrane. “Even without current, liquid passes through the membrane,” says Dirk Hegemann of Empa’s Advanced Fibers lab.
“However, as soon as an electrical voltage is applied, the pumping effect increases significantly,” he continues. According to Empa, a Swiss materials science and technology research institute, the membrane can pump out around 10 litres of liquid per square metre per hour by electro-osmosis.
Ski-jacket integration
The final version of the product will have the electro-osmosis membrane integrated into a ski jacket within a number of functional layers. Simon Annaheim from Empa’s Biomimetic Membranes and Textiles lab, says: “Thanks to our new physical and numerical models, we were able to optimise the textile structure of the HYDRO_BOT technology.”
Empa’s experiments in its special climate chamber shave shown that the electro-osmotic principle not only work in aspects of physics but that it also meets the physiological requirements of the human body.
Osmotex anticipates that the jackets with HYDRO_BOT technology will be available on the market for the 2018/19 season. Meanwhile, Norwegian sportswear manufacturer KJUS and Swiss textile company Schoeller are developing the technology further.
Schoeller displayed a prototype version of an electro-osmosis jacket at ISPO Munich 2018, the world’s leading trade fair for the sports industry, on 28-31 January. This was the first time the jacket had been on display to the public.
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