Dehydration can now be measured with ease thanks to laser machined filter paper. Researchers at Purdue University used CO2 laser processing to create a radial array of strips on their new skin patches that change color to indicate different levels of hydration. Purdue University researchers show off a newly developed skin patch that changes color to indicate different levels of hydration, representing a potential new medical technology. Here, the patch is shown recording hydration at specific time intervals. Courtesy of Purdue University/Vaibhav Jain, Manuel Ochoa. The arrays are laminated with a water-impermeable film to form microchannels. These channels are loaded with water-activated dye. As a person sweats, the strips are activated, changing from blue to red to provide easily identifiable levels of moisture loss. Babak Ziaie, a researcher and professor of biomedical engineering and electrical and computer engineering at Purdue, told Photonics Media that using photonics technology speeds up the production of their innovative product. “By using the CO2 laser and photonics advances we are able to produce the products at large scale and at a very low price. It literally costs a few pennies to create each one with the laser,” he said. Potentially, the paper-based skin patch could be used by athletes, military personnel and many others to help prevent dehydration. Conventional methods for monitoring hydration are either invasive, require non-portable equipment, or do not yield results immediately. “Ours is a single device that gives visual feedback. It is different than any other product on the market,” said Ziaie. “With our laser-based production, we can accommodate large-volume manufacturing.” The Purdue team has filed a patent application for the concept through the Office of Technology Commercialization of the Purdue Research Foundation. They are currently doing beta testing and talking to different businesses to conduct field tests.