New wearable sensor tracks body water hydration in real time

Staying hydrated sounds simple. But when temperatures rise and the body sweats more, it's not always easy to know when you're running low on water. Dehydration can sneak up quickly—whether you're playing football, battling a fire, working outside, or just spending your day in an office. Even mild dehydration can affect how you think, move, and feel. More serious cases can be dangerous, leading to heatstroke, kidney problems, or even heart trouble.

Despite the risks, keeping track of how much water your body needs—and when it needs it—is hard. Traditional tools like blood tests or urine samples are slow, uncomfortable, and only give you a one-time reading. New solutions are needed that are fast, reliable, and easy to use in daily life. Now, scientists at The University of Texas at Austin may have found a better way.

Led by engineer Nanshu Lu, a team at UT Austin developed a small wearable sensor that tracks hydration in real time without needles, wires, or lab tests. Their study, published in Proceedings of the National Academy of Sciences, shows that this new tool can give continuous hydration feedback as you move through your day.

“Dehydration is a silent threat that affects millions of people every day,” said Lu, a professor in the Cockrell School of Engineering. “Our wearable sensor provides a simple, effective way to monitor hydration levels in real time, empowering individuals to take proactive steps to stay healthy and perform at their best.”

The sensor uses bioimpedance, a technique that checks how electricity flows through the body. Since water is a strong conductor of electricity, tissues filled with water let the electrical current move easily. When the body loses water, the tissues resist the flow more. By placing electrodes across the arm, the device sends a small and safe electrical signal through the skin. This signal changes based on how much water is in the muscle.

To make sure their device worked well in both lab settings and real life, the team ran a series of experiments. In one test, eight volunteers took a diuretic—a drug that causes the body to lose fluid. As participants dehydrated, their arm’s electrical resistance increased. The sensor’s readings strongly matched the amount of body weight lost, with a Pearson correlation of 0.956 ± 0.033. This means that changes in the sensor readings closely followed how much water people actually lost.

“We saw that arm bioimpedance is not only sensitive to hydration changes but also aligns closely with whole-body hydration measurements,” said Matija Jankovic, a post-doctoral researcher in Lu's lab and co-author of the study. “This means the sensor can be a reliable surrogate for tracking hydration levels, even during everyday activities like walking, working, or exercising.”

In another experiment, participants wore the sensor during 24 hours of normal life—eating, sleeping, and moving around freely. Even with regular activity, the device still captured clear changes in hydration. Whether people were drinking fluids or sweating it out, the device responded right away. Unlike older technologies, this sensor doesn’t require large machines or lab visits. It's wireless, dry, and flexible enough to move with your body. Data goes straight to a smartphone app, so users can track hydration wherever they are.

This device isn't just for athletes or emergency workers. It has the potential to benefit anyone who wants to stay well-hydrated, from students on campus to older adults managing health conditions. Hydration plays a central role in how the body works. Water helps organs function, supports body temperature, and keeps your brain and muscles performing their best. Yet many people don't drink enough water. Chronic dehydration is common, and often overlooked.

Even slight dehydration can reduce focus, coordination, and endurance. Left unchecked, it can raise the risk of serious problems, like kidney stones or heart strain. That’s why a simple tool that tracks hydration without effort could make a big difference.

The new sensor might also help patients with medical conditions. Continuous hydration monitoring could support better care for kidney disease, cardiovascular problems, or long-term dehydration. And it could help prevent sudden issues during recovery from illness or surgery. “And hopefully, it could help our Longhorn student athletes compete and stay healthy on hot days,” Lu added.

For now, the sensor measures relative changes in hydration—how your levels shift during the day. But researchers are already working on the next step: building a database of reference values to estimate absolute hydration status. By collecting readings from many people, the team hopes to create a baseline that shows what “normal” hydration looks like.

The researchers are also exploring new designs to make the device even easier to wear. These include breathable “e-tattoos” and sweat-wicking materials for long-term comfort. They plan to test the sensor on larger groups of people and expand to other parts of the body, like the forearm or thigh.

A key finding in their simulations was that when electrode placement was optimized across the arm, a strong linear link formed between the sensor readings and the electrical resistance of muscle. Since muscle resistance changes based on water content, this result proved that arm-based measurements could stand in for full-body data.By comparing these readings to known hydration standards, it may even be possible to estimate someone’s absolute hydration state—not just how it changes over time.

“This is just the beginning,” Lu said. “Our goal is to make simple hydration monitoring accessible to everyone.”

From long shifts in the sun to intense training sessions, the dangers of dehydration won’t go away. But with this wearable device, the ability to track and manage hydration could finally be within reach—for anyone, anywhere.

Note: The article above provided above by The Brighter Side of News.

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