Patch monitors the water and electrolyte balance during exercise

A new patch with integrated sensors monitors the water and electrolyte balance during exercise in real time. In the future, the plaster should help competitive athletes to optimize their fluid balance during competitions.

Barrington (USA). A team led by Lindsay Baker from the Gatorade Sports Science Institute in Barrington has presented a high-tech plaster with an integrated sweat sensor that is designed to help competitive athletes monitor their water and electrolyte balance. According to the magazine Science Advances published papers, the sensor records the salt concentration and the amount of sweat in real time and uses this to determine the fluid requirement.

The recently presented prototype contains two serpentine microchannels. The first microchannel contains a dye that changes color depending on the amount of sweat. The second microchannel contains a hydrogel in which a chemical reaction is generated when perspiration penetrates. Depending on the salt content of the sweat, the hydrogel turns pink to a greater or lesser extent.

The color changes in the two microchannels can be monitored in real time with a smartphone camera. A corresponding app uses the colors to automatically determine the athletes’ water and electrolyte requirements.

Practical test with 312 athletes

To test the new sweat sensor, the scientists carried out an experiment with 312 test persons in different sports, including running, cycling and tennis. Some of the test persons wore additional sweat-absorbing pads during sporting activities, with which the amount of sweat released could later be analyzed in the laboratory. It turned out that both measurement methods deliver almost identical results.

The salt content, which the scientists determined using the chloride concentration, could also be determined with almost the same precision using both measurement methods. The analysis in the laboratory only provided better results for very small amounts of sweat.

Further optimization of the welding sensor

The tests show that the measurement of the amount of sweat by the new sensor delivers usable results during training. Further development steps should improve the measurement of the salinity even more.

In the future, the sensor plaster could then help competitive and professional athletes to monitor their sweating behavior during training and during competition and to plan their intake of water or electrolyte drinks more precisely. In addition, the scientists also see potential for use in some disciplines of popular sports, including, above all, endurance sports such as racing cyclists or marathons, in which the fluid balance is of great importance.

Science Advances, doi: 10.1126/sciadv.abe3929

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