Scientists at King Abdullah University of Science and Technology (KAUST) are tracking the human body's water levels to determine if a person is dehydrated by measuring how their skin interacts with a touchscreen.

The team used a basic capacitive sensor — like those found in smartphone screens — that is capable of detecting subtle changes in skin moisture. The researchers explained that when a fingertip touches the sensor, it notes alterations in skin capacitance, which is a measure of how effectively the skin stores electric charge, which can vary according to hydration levels.

Source: KAUST

The team believes that such data might one day enable people to monitor their hydration in real time without the need for needles, wearables or lab work. Instead, a simple touch could alert someone to drink water or replenish fluids before the onset of symptoms like dizziness or fatigue.

"We envision real-time, everyday, user-friendly hydration monitoring, where users simply place their finger on their smartphone screen to assess their hydration status," the researchers added.

To test the technology, the KAUST researchers obtained more than 4,000 fingertip readings from fasting volunteers as well as from athletes engaged in a game of ultimate Frisbee or working out at the gym. Machine-learning models were then trained to turn tiny changes in skin conductance into a measure of the body's water content.

During trials of the technology, the team was able to distinguish between hydrated and dehydrated states up to 92% of the time among athletes and 87% of the time among fasting individuals.

The technology is detailed in the article, “Noninvasive Monitoring of Dehydration of Fasting and Sportspeople Subjects via Skin Capacitance,” which appears in the IEEE Sensors Journal.