Electro-osmosis in Performance Wear
Wearable technology has been around for what seems to be an eternity of helping us to be better, faster, healthier, stronger.
Yet, tracking the progress of apparel market, only an insignificant amount of brands are successfully providing truly uncompromising products that feature this new, exciting wave of devices promising to change the way we perform. My work for high-end ski wear brand Kjus has inspired me to dig a bit deeper into a new technology on the market, which could change forever winter sports, as well as, in the near future, our relationship with apparel.
- Why is moisture wicking in performance wear important?
The human body as it is acts like the perfect mechanism to take care of our demands, signifying and reacting when we need it, carrying us every day, helping us perform all our desired activities, communicate, work, do sports. One could say evolution has shaped it in a way that would best assist us in living a wholesome life. As ever curious creatures, however, we like to explore our possibilities, our limits, and test how far we can go, how fast we can be, how much better than yesterday we are able to perform. This is why, we constantly develop more sensitive and more intuitive technology that could work in harmony with our own bodies, helping us get this unique sense of achievement every time we overcome our limits.
As societal ambitions constantly grow, it is important to find more creative ways of dealing with the limitations of our own bodies, and a sensible way to start is by tackling an issue all athletes experience. Sweating.
The amount of liquid and vapour released by our bodies during exercise can vary depending on the athlete and activity and is a healthy reaction of the body, in some cases, however, it could seriously affect the performance, and, sometimes, health too.
In extremely hot conditions, for instance, trapped moisture heats up and can cause fatigue and diminished performance, whereas in cold conditions it cools down and could lead to chilling and hypothermia. Due to excess moisture, garments also become considerably heavier and may cause skin damage as a result of chafing.
During exercise the human body reaches a temperature greater than 37 °C, which is the reason sweat is produced. Liquid is then absorbed more or less by any fabric close to the athlete’s skin, however, if moisture fails to evaporate, it starts heating up, causing the body to produce even more sweat.
This means that the fabric immediately next to the skin should be able to perform two important tasks – absorb moisture, and transport it to the surface, from where it goes into the atmosphere. This occurs by a capillary force (wicking) and should be valid for liquid, as well as vapour, in order to ensure maximal comfort to the body. Looking into the wicking process, the larger the evaporation area, the quicker the process, which means that wicking speeds up when the gaps between fibres become thinner, consequently when fibres are finer. It is therefore important to increase both the hydrophilic and hydrophobic qualities of materials used, which is possible using a few methods: changing the ﬁbre surface chemistry, usage of modiﬁed cross sectional ﬁbres, yarn engineering (blending), fabric engineering and fabric chemical treatments with silicones, enzymes or alkalis.
- What makes fabrics moisture wicking?
Currently, on the market there are a number of companies, known for high-quality production or innovative technology in the making of moisture wicking fabrics. A good example is the Dutch company Teijin, which, with its moisture wicking products, is catering for various businesses – from automotive and oil & gas, to civil engineering, ballistic protection, providing materials with moisture management functions.
Knitted fabric made with Fibaliver® material, which is also available on the market, changes the stitch density in order to improve air permeability when humidity is sensed.
Another approach in the manufacturing of moisture wicking materials is the usage of mineral particles in yarn production with special cross section, which causes the end product to manage moisture and provide a cool feel. In the making of this yarn, a Flycool® powder is used to create the fabric, which is a mixture of two main components – minerals making for a cool feeling (glass, malachite, marble, ore, iron, gold), and materials, enabling heat dissipation (graphite, silicon, aluminium, nitrogen, boron).
So far, it is known that wicking abilities increase proportionately to the increase of acrylic content in yarn blends, as well as with the usage of coarse yarns. In order to boost the wicking ability of these fabrics, another process has been explored, which could be implemented in performance gear where needed.
- What is electro-osmosis?
Electro-osmotic flow (electro-osmosis) is the motion of liquid, induced by an applied potential across a porous material, capillary tube, membrane, microchannel, or any other fluid conduit.
Upon the application of voltage, a net excess of positive ions in the adjacent liquid migrates, towards the cathode, drawing the liquid along them.
Using a membrane, more specifically, as a viable option for the textile industry, electro-osmosis causes protons moving through this proton exchange membrane (PEM) to drag water molecules from one side (anode) to the other (cathode), or through the membrane. Due to this process, bulk fluid motion is observed, the velocity of which is linearly proportional to the applied electric field, and dependent on the material used to conduct the microchannel.
- Implementation of electro-osmosis in sportswear design.
The Swiss Federal Laboratories for Material Science EMPA St. Gallen were first to implement this approach in apparel, working in cooperation with Thalwil-based Osmotex. In order to appropriately execute the principles of electro-osmosis and apply them to apparel design, they use a polymer membrane with a thickness of only 20 micrometers, coated on both sides with a noble metal by means of plasma coating. Silver and gold are both appropriate facilitators of conduction, gold being significantly more durable than silver, making it a preferred coating for the electrodes.
Swiss performance skiwear brand KJUS has adopted this technology for their 7Sphere Hydro_Bot jacket, allowing complete comfort and wicking in extreme conditions.
To achieve this, two back panels are incorporated in the back, which is a high-sweat zone, using body mapping. A membrane coated with 0.2 grams of gold per jacket is then inserted, made up of trillions of pores per m2 and surrounded by conductive fabric. A small electrical pulse of 1.5 volts is then applied to the membrane (gold-lined HYDRO_BOT fabric), causing the salt ions of sweat to move through tiny pores in the membrane, along with the liquid, and transporting it to the outside.
The HYDRO_BOT membrane can pump out 10 litres of liquid per square meter and hour, using electro-osmosis. It is equipped with battery, which can be switched on and off depending on activity, wearer, and perspiration. Even without current, liquid still passes through the membrane, however when an electrical shock is applied, the pumping effect increases significantly, turning the tiny pores into micro-pumps.
The 7Sphere jacket’s pumping principle might sound complicated but it is actually quite easy to use – it could simply be switched on and off with the integrated control unit or via Bluetooth from the iPhone and Android compatible app.
- What is the future of electro-osmosis in performance wear?
Although electro-osmosis is a relatively simple process, there is a long way to go, until it is fully implemented by other apparel companies.
If we look at the upsides of this technology, it makes for truly uncompromising products, causing the HYDRO_BOT jacket to be up to 10 times more efficient than jackets with regular membranes, as the usage of regular membranes doesn’t allow pumping out of sweat fast enough in tough weather conditions. Electro-osmosis is also not adversely affected by freezing temperatures, which grants the best performance in any weather and it allows some excellent self-monitoring features. The app coming with Kjus 7Sphere HYDRO_BOT jacket is also able to give recommendations on how to regulate body temperature, minimizing sweat production, based on the amount of sweat passing through the back panels.
A main drawback is the cost of manufacturing of such membranes, due to the usage of gold or silver coating, significantly impacting the price of the final product. It is not yet clear whether this could be implemented in more high-stretch garments (such as baselayers and gym wear) , due to breakage (the membrane panels should not be twisted).
Other industries, however, have reported further developments based on electro-osmosis, in the areas such as work and protective clothing, medical applications like hospital bed covers and wound care, air conditioning systems, microfluids, cosmetics and many more.
Electro-osmotic textiles for athletes, posted :Monday, January 28th, 2018
Electro-osmotic textiles for athletes, posted :Monday, January 28th, 2018
From: Engineering Textiles, 2009
Moisture-management properties of bi-layer knitted fabrics for sportswear
T Suganthi, P SenthilkumarFirst Published February 9, 2017
Transfer Wicking Mechanisms of Knitted Fabrics Used as Undergarments for Outdoor Activities
Q. Zhuang, S.C. Harlock, D.B. Brook
First Published August 1, 2002
The Interaction of Water with Fabrics
Rita M. Crow, Randall J. Osczevski
First Published April 1, 1998
Moisture Vapor Transport Behavior of Polyester Knit Fabrics
C. Prahsarn, R. L. Barker, B. S. Gupta
First Published April 1, 2005
Wicking Behavior and Drying Capability of Functional Knitted Fabrics
R. Fangueiro, A. Filgueiras, F. Soutinho, …
First Published March 18, 2010
Effects of fabrics with dynamic moisture transfer properties on skin temperature in females during exercise and recovery
Xiaofen Lin, Yi Li, Jinyun Zhou, …
First Published April 10, 2015
Significance of Moisture Management for High Performance Textile Fabrics
Dr. S. K. Chinta, Ms. Pooja D. Gujar
D.K.T.E Textile & Engineering Institute, Ichalkaranji, India
International Journal of Innovative Research in Science, Engineering and Technology
Cornell University, College of Engineering, Kirby Research Group
16th November 2018, Hünenberg, New ski jacket uses electro-osmotic technology