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The potential applications of scientific processes are not always obvious at the time of their development…
Microfluidics, the precise control of fluids used in lab-on-a-chip applications, could wick away sweat to help keep you fresh and dry, according to engineers at the University of California, Davis.
Lab-on-a-chip devices rely on being able to move, mix or separate extremely small volumes of fluid to perform combinations of laboratory tasks in a very compact space, often no larger than a few square centimetres. Developing new devices requires a good understanding of how fluids will move through defined channels, and how to manipulate this flow to maintain the required reactions.
Inspired by this, graduate students Siyuan Xing and Jia Jiang in the Micro-Nano Innovations lab (cleverly abbreviated to MiNI) developed a new textile that incorporates hydrophilic threads into a highly-water repelling fabric. The threads attract and channel water, or sweat, allowing it to be moved from its source (in this case, perhaps your armpits) to another location on the outside of the garment. From there, it can simply run off or evaporate, meaning the fabric can remain dry, comfortable and breathable.
Even under extremely sweaty conditions, the channels will continue to move water to the outside of the garment, as the hydrophilic nature of the fabric surrounding the channels works to pump the water through. The surface tension of droplets on the outside also establishes a pressure gradient, so even if the channels themselves are completely saturated, the pumping effect continues unabated.
— Water droplets are vigorously repelled by the fabric — unless they are taken up by hydrophilic threads. Courtesy of Holly Ober, UC Davis
Their results, published in Lab on a Chip, demonstrate continuous pumping of 1.3 millilitres per hour for a square centimetre of fabric (1.3ml/h/cm2), far exceeding their estimated average human sweat rate of up to 0.21ml/h/cm2.
Waterproof, breathable fabrics are not a new idea. Athletes of all abilities can suffer from clothing becoming damp, clingy and uncomfortable, which can lead to painful chafing in endurance sports or hiking.
This new fabric may be high-tech, but could be low cost. The hydrophilic channels themselves could be made from cotton, simply stitched in the right pattern into existing water-resistant fabrics. So the next time you go for a run, you could be wearing lab-on-a-chip technology!