A skin sensor for analyzing the composition of sweat
Researchers at Northwestern University, working under the guidance of Professor John A. Rogers, have developed a first-of-its-kind soft, flexible microfluidic sensor that adheres firmly to the skin and measures the content of various compounds in human sweat during exercise.
Sweat is a saturated solution of chemical compounds, the analysis of concentrations of which can provide important information about the state of human health. However, traditional methods of collecting sweat for laboratory analysis using adsorbing sponges severely limit the possibilities of this approach.
The authors, who have long been engaged in the development of "epidermal" electronic platforms, which are thin flexible devices attached to the skin surface for monitoring various physiological parameters, decided to adapt such a platform to expand the capabilities of sweat analysis. To do this, they equipped it with a complex system of microfluidic channels and reservoirs.
The resulting device, whose size and thickness are comparable to the size of a 25-cent coin, is designed for single use for several hours. It is glued directly to the skin of the forearm or back. During physical exercises, sweat enters through four thinnest microfluidic channels into the device, where it is distributed over four circular reservoirs. In these tanks, a reaction occurs that causes a change in the color of the chemical compounds contained in them, the intensity of which is quantitatively correlated with the concentrations of glucose, chloride and lactate, as well as with the level of acidity.
These four biomarkers were chosen because their combination accurately reflects the state of human health. In addition, the device allows you to determine the intensity of sweating and moisture loss by the body, as well as, if necessary, save sweat samples for subsequent laboratory analysis.
Wirelessly, the device launches an application on the smartphone that takes a photo of it and analyzes the image to obtain data on the concentrations of biomarkers. This information can help a person to learn in a timely manner about the need for measures such as drinking water or special drinks, as well as possible medical problems.
Two groups of athletes took part in the study of the accuracy and reliability of the device: one group was engaged in exercise bikes in controlled conditions of the fitness center, and the other took part in the long-distance cycling race El Tour de Tucson, held in arid and difficult conditions. Sensors were placed on the forearms and backs of athletes.
For the first group of athletes, the authors compared the concentrations of biomarkers in samples of the same sweat obtained using a new sensor and using traditional laboratory methods. The obtained results confirmed the comparability of the obtained results.
The second group of athletes tested the reliability of the sensor in difficult and unpredictable desert conditions. The device proved its reliability, it was firmly held on the skin of athletes, did not leak and provided reliable data.
The developers note that the capabilities of the new device are not limited to analyzing the compounds contained in sweat. At the present stage, it makes it possible to identify a biomarker of cystic fibrosis, which indicates the prospects of its use in clinical practice.
Article A. Koh et al. A soft, wearable microfluidic device for the capture, storage, and colorimetric sensing of sweat is published in the journal Science Translational Medicine.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on materials from Northwestern University: Researchers develop soft, microfluidic 'lab on the skin' for sweat analysis.
25.11.2016