This ‘HYDRO_BOT’ is said to use the same principles that enable plants to draw water from the soil via their roots. The creators say this wearable technology accelerates the process by applying a voltage of around 1.5 volts.
According to the team, a polymer membrane with a thickness of 20 micrometers is used to ensure that liquid is actively transported by electro-osmosis from the inside to the outside. The polymer membrane is coated with a noble metal by means of plasma coating. The creators have said this is done by using just under 0.2 grams of gold per ski jacket. This has an impact on the price of the membrane, but the benefits lie in its durability.
When an electrical voltage is applied to the membrane, salt ions – and with them the liquid surrounding them – migrate through pores in the membrane to the outside.
The membrane is equipped with a conventional battery to attract these salt irons, which the creators say can be switched on depending on weather and body activity.
“Even without current, liquid passes through the membrane. However, as soon as an electrical voltage is applied, the pumping effect increases significantly,”explained Dirk Hegemann from Empa’s Advanced Fibers lab.
The membrane is said to be able to pump out around ten litres of liquid per square meter and hour by electro-osmosis.
The idea is to for the electro-osmotic membrane to be integrated into a ski jacket within various functional layers.
“Thanks to our new physical and numerical models, we were able to optimise the textile structure of the HYDRO_BOT technology," said Simon Annaheim from Empa’s Biomimetic Membranes and Textiles lab.
Empa conducted experiments in its climate chambers, which they claim demonstrated that the electro-osmotic principle not only works in aspects of physics but also meets the physiological requirements of the human body.
Using the anatomically shaped sweat manikin known as ‘SAM’ apparently simulated how the human body behaves during exercise. SAM moved, heated up and ejected precisely defined quantities of liquid through 125 tiny nozzles.
“SAM and the data it provided us with enabled us to objectively analyse the wearing comfort and functionality of HYDRO_BOT clothing," Annaheim concluded.