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A simple sweat test for cystic fibrosis: Cystic fibrosis is diagnosed in infants by use of sweat testing as elevated chloride concentrations in sweat are indicative of cystic fibrosis. The current approach can have poor sensitivity and require repeated testing. Toward the goal of developing a noninvasive, simple test for cystic fibrosis, Ray et al. devised an adhesive microfluidic device, or "sweat sticker," to capture and analyze sweat in real time with colorimetric readout. 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. Results support further testing of the sweat stickers in larger studies. The concentration of chloride in sweat remains the most robust biomarker for confirmatory diagnosis of cystic fibrosis (CF), a common life-shortening genetic disorder. Early diagnosis via quantitative assessment of sweat chloride allows prompt initiation of care and is critically important to extend life expectancy and improve quality of life. The collection and analysis of sweat using conventional wrist-strapped devices and iontophoresis can be cumbersome, particularly for infants with fragile skin, who often have insufficient sweat production. Here, we introduce a soft, epidermal microfluidic device ("sweat sticker") designed for the simple and rapid collection and analysis of sweat. Intimate, conformal coupling with the skin supports nearly perfect efficiency in sweat collection without leakage. 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. Clinical validation studies involving patients with CF and healthy subjects, across a spectrum of age groups, support clinical equivalence compared to existing device platforms in terms of accuracy and demonstrate meaningful reductions in rates of leakage. The wearable microfluidic technologies and smartphone-based analytics reported here establish the foundation for diagnosis of CF outside of clinical settings. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the use of skin-interfaced wearable microfluidic device and smartphone image processing platform to analyze regional sweating rate and sweat chloride concentration (CI-) for sports science applications. The aim is to determine the correct time and amount of personalized fluid-electrolyte intake of athletes participating in competitive sports to maintain their proper hydration and electrolyte balance.

Wearable sweat sensors rely either on electronics for electrochemical detection or on colorimetry for visual readout. Non-ideal form factors represent disadvantages of the former, while semiquantitative operation and narrow scope of measurable biomarkers characterize the latter. Here, we introduce a battery-free, wireless electronic sensing platform inspired by biofuel cells that integrates chronometric microfluidic platforms with embedded colorimetric assays. The resulting sensors combine advantages of electronic and microfluidic functionality in a platform that is significantly lighter, cheaper, and smaller than alternatives. A demonstration device simultaneously monitors sweat rate/loss, pH, lactate, glucose, and chloride. Systematic studies of the electronics, microfluidics, and integration schemes establish the key design considerations and performance attributes. Two-day human trials that compare concentrations of glucose and lactate in sweat and blood suggest a potential basis for noninvasive, semi-quantitative tracking of physiological status.