NC State researchers John Muth and Yong Zhu have developed a wearable hydration monitor that will cost only a dollar. Funded through the NC State-based ASSIST Engineering Research Center, which receives funding from the National Science Foundation, the wireless sensor that can be worn on the wrist or the chest and that monitors the dehydration level of the skin. The signal from the device can then easily be transmitted to a laptop or a smartphone.

“The sensor consists of two electrodes made of an elastic polymer composite that contains conductive silver nanowires,” Zhu said. “These electrodes monitor the electrical properties of the skin. Because the skin’s electric properties change in a predictable way based on an individual’s hydration, the readings from the electrodes can tell how hydrated the skin is.”

Shanshan Yao, a postdoctoral research scholar who has worked on this project noted that this is something which the commercial devices are unable to do.

“The skin hydration monitors on the market typically implement rigid electrodes and the overall system is bulky, expensive and hard to be worn continuously,” Yao said.

The applications of the device are wide and far-reaching. A person’s water content is crucial to regulate body temperature, blood pressure and heart rate, among other things. Skin hydration is an important way to analyze various disease states and to evaluate the effectiveness of medical therapies and cosmetic treatments. Therefore, skin hydration sensors could potentially benefit athletes, patients, first-responders, military personnel and people who work or live in extreme conditions, as well as cosmetic companies.

Currently, the researchers have successfully verified that the measurements are insensitive to the surrounding humidity level. They are also expanding the scope of the device and developing a prototype that includes hydration sensor, electrocardiography (ECG) electrodes, and strain sensor that can monitor human motions.

While the research team is faced with testing under different conditions and scaling-up, a critical step yet to be accomplished is to attain commercialization by manufacturing at a large scale to lower costs.

“When we can make the devices in large quantity, we will be happy to consider making them available to NC State students,” Zhu said.