Researchers, including one of Indian origin, have developed a low-cost paper-based skin patch that changes colour to indicate different levels of hydration, which may be used by marathon runners and military personnel to help prevent dehydration. “Hydration in humans is a delicate parameter,” said Babak Ziaie, professor at Purdue University in the US.
“Even small deviations such as 2 per cent from normal levels can affect a person’s cognitive and physical performance by more than 30 per cent,” said Ziaie.
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The palm-size patch consists of filter paper that is laser-machined to create a radial array of strips, which are laminated with a water-impermeable film to form microchannels.
The channels are loaded with a water-activated dye at one end. As sweat secretion increases, the strips are activated sequentially, changing from blue to red and providing easily identifiable levels of moisture loss.
Conventional methods for monitoring hydration are either invasive, require non-portable equipment or do not yield results immediately. “In comparison, our approach is a fast, user-friendly dermal patch for collecting and measuring sweat secretion. And our fabrication process could be scaled up to large-volume manufacturing,” Ziaie said.
The patch was tested at a sweating rate of 90 microliters per hour over a square centimetre of skin, which corresponds to normal human sweat rates.
“We have talked to many experts including marathon directors, the Ironman World Championship, Olympic triathlon athletes and many collegiate and professional coaches, athletes, race directors and EMTs to validate the need for this kind of product,” said graduate student Vaibhav Jain.