Parents of newborns who receive a positive cystic fibrosis (CF) screening will admit to licking their babies. A lot. That’s understandable, considering the danger of malnutrition and other complications for infants in their first weeks of life. 

Early detection reduces the risk of these complications and improves treatment outcomes. A team of researchers at Northwestern University have developed a soft skin patch that offers results within minutes, rather than the days it can take to receive a diagnosis from conventional sweat tests.

CF affects one in every 3,300 babies born in the United States. The disease prevents a chemical called chloride from moving through cell membranes as it should. This results in thick mucus formation that builds up within the body, primarily in the lungs, digestive system, and other organs. The chloride also causes sweat to retain extra salt, hence the baby “lick test.”

Newborns have a heel prick test within a few days of birth to screen for CF. Parents who receive a positive screen must bring their infant in for a sweat test. Traditionally, this test requires a hard device strapped to the baby’s wrist. Following the sweat test, anxious parents must wait days for lab results to confirm whether the child has the disease. Smaller babies may not produce enough sweat, and the wrist device can slip and slide, compromising the sample; in these instances, the test must be repeated.  

Clinical trials at the Cystic Fibrosis Center at the Ann & Robert H. Lurie Children’s Hospital of Chicago showed that the skin-mounted sticker adheres comfortably to the baby’s arm and collects 33% more sweat than the traditional test, reducing the need for repeated testing. The rapid results performed with comparable accuracy to standard testing.

The sticker collects sweat in circular channels that change color when chloride is present. Pediatricians can use a smartphone to analyze the colors and make a diagnosis. They can also photograph the sticker and send the image to a lab for immediate confirmation.

The sticker could decrease the amount of time it takes for infants to receive a conclusive CF diagnosis, improving outcomes by accelerating the beginning of treatment. It may also make CF testing in medically underserved areas easier to access.

The research team published the results of their findings in the journal Science Translational Medicine. The team believes the sticker has applications beyond diagnosis, such as monitoring disease progression in children.