Researchers at Northwestern University have developed a sticker that can measure chloride levels in sweat in real-time through a simple color change.
The sticker is applied to the skin and wicks sweat inside itself through a set of microfluidic channels, where an onboard bioassay measures chloride levels, a marker of cystic fibrosis. The technology may end up simplifying cystic fibrosis diagnosis in newborns.
Cystic fibrosis is a genetic disease caused by a malfunctioning chloride channel in epithelial cells. It typically results in very thick mucus in the airways, leading to serious breathing issues and infections, and it can also affect the digestive system. Early diagnosis is important, as patients can suffer malnourishment if they do not receive appropriate treatment soon after birth.
At present, diagnosis involves a heel prick test, and if this reveals an abnormality then clinicians place a bulky “sweat collector” bracelet around the child’s wrist, to perform a lab analysis of sweat chloride levels. In theory, the device should be able to collect enough sweat for analysis within about 30 minutes, but it often can’t.
“Some parents bring their baby in for testing and are sent home without a confirmed result because the device was unable to collect enough sweat,” said Susanna McColley, a researcher involved in the study, via a press release. “They go home, without knowing if their baby has a serious disease or not, and their baby cannot yet start treatment. It can be agonizing.”
To address this, these researchers have developed a sticker that can collect and analyze sweat for chloride levels automatically, producing a noticeable color change. Parents can take a picture of the skin sticker once a color changes occurs and send the image to a clinician for analysis. A laboratory is cut out of the picture, allowing for a much easier diagnostic process.
“The device uses a network of microfluidic channels to collect sweat directly from the skin and route it to chambers to react with chemical reagents,” said Tyler Ray, another researcher involved in the project. “Those reagents cause a change in color that correlates to the chloride concentration level. By collecting and analyzing sweat at the point of collection, we can enable an earlier diagnosis. This is crucial for preventing severe complications and improving long-term patient outcomes.”
Interestingly, the technology may also be useful for cystic fibrosis patients who want to monitor their condition or see if a therapy is helping. “Because this device is untethered, we plan to use it beyond clinical environments,” said Roozbeh Ghaffari, another researcher who worked on the study. “In light of these new capabilities and further clinical validation, cystic fibrosis patients receiving treatment could someday use the sweat sticker at home to track their symptoms and hydration levels during daily living.”