“Sweat Stickers” May Ease Cystic Fibrosis Diagnosis and Management

An elevated chloride concentration in an infant’s sweat is indicative of the genetic, progressive disease cystic fibrosis. Many current diagnostics work by detecting levels of chloride in sweat, however, current approaches can have poor sensitivity, often need to be repeated, and use unwieldy wrist-wrapped devices, making them impractical for infants with soft skin and low levels of sweat.

Now, a team has developed a solution: an adhesive, noninvasive, microfluidic device called a “sweat sticker” that may streamline the early diagnosis of cystic fibrosis. The sweat stickers, which capture and analyze sweat in real time with colorimetric readout, enable scientists to easily gather and analyze sweat from the skin of infants and children. Further, benchtop testing and validation in patients with cystic fibrosis showed that smartphone imaging of sweat stickers adhered to the skin could monitor sweat chloride concentrations.

This work is published in Science Translational Medicine in the article, “Soft, skin-interfaced sweat stickers for cystic fibrosis diagnosis and management.”

Diagnosing cystic fibrosis in infancy or childhood is critical to achieving good outcomes, as current treatments must be given early to extend lifespans and alter the course of the disease. To address this need, a collaborative team led by the group of John Rogers, PhD, professor of materials science and engineering, and the founding director of the Center on Bio-Integrated Electronics at Northwestern University, developed their sweat stickers—soft, microfluidic devices with a multilayered design that can conform to the skin of both infants and adults.

When tested, the stickers collected sweat as effectively as a traditional method named MSCS in a pilot study with 18 healthy subjects and 33 patients. The subjects ranged from 2 months to 51 years old. Unlike MSCS, the stickers gathered enough sweat to avoid any repeated tests and did not cause uncomfortable skin indentations in infants. This suggests that the stickers could address design obstacles that have held back the diagnosis and treatment of cystic fibrosis in pediatric patients.

A sweat sticker on an infant after the conclusion of a sweat test. [T.R. Ray et al., Science Translational Medicine (2021)]The stickers rapidly collect and store sweat from the skin, which can be analyzed using a smartphone application.

The authors noted that, “intimate, conformal coupling with the skin supports nearly perfect efficiency in sweat collection without leakage” and that, “real-time image analysis of chloride reagents allows for quantitative assessment of chloride concentrations using a smartphone camera, without requiring extraction of sweat or external analysis.”

The researchers call for larger studies to further establish their platform’s accuracy and precision. They noted that the wearable microfluidic technologies and smartphone-based analytics reported “establish the foundation for diagnosis of CF outside of clinical settings.”