Last December, several members of the U.S. Air Force volunteered for a sweaty mission. During extra workout sessions at the Air Force Research Laboratory in Ohio, the volunteers wore on their backs adhesive patches that collected their perspiration. Sensors in the patches were able to detect the specific levels of electrolytes in the sweat the volunteers released. That data was transmitted wirelessly to a laptop computer app where researchers could analyze it in real time.
“We can measure the sodium and potassium levels — the electrolyte balance that correlates with dehydration,” says GE materials scientist Azar Alizadeh, who is developing the patch with her team at GE Global Research and outside partners including the Nano-Bio Manufacturing Consortium, NextFlex, Air Force Research Laboratory, State University of New York, Binghamton, and New York State’s Empire State Development arm. “This could be so important to anyone who is working in hot or high-stress conditions, like firefighters, miners or elite athletes.” The research was recently published in the Royal Society of Chemistry’s Lab on a Chip journal.
The disposable wireless patch, which can fit in the palm of your hand, is made from materials used in medical tape and wound dressings. It contains two key elements: microfluidics technology and a sensor. GE engineers originally used microfluidics in jet engines to manipulate the natural airflow currents coming through the engine and channel them to optimize efficiency and performance. In a similar sense, Alizadeh has created a patch with tiny pathways and valves that can channel sweat into a conduit that contains a sensor.
“At the sensing site, the sensor is designed to detect the sodium or potassium levels, and when that happens, an electric signal is produced,” Alizadeh says. “This signal is transmitted via Bluetooth to the computer.” Right now, the wireless range of the patch is approximately 30 feet. If the person wearing the patch is getting dehydrated, those electrolytes will be off-balance, and whoever is monitoring the patch program will be able to see this in real time.
Alizadeh says that her team at GE Global Research is now “in the process of converting this program to a mobile app.” They are working with Dublin City University, the wearable technology company Shimmer Sensing, and the technology company UES, Inc. Alizadeh says the patch — which is still about two years away from getting on the market — eventually will be programmed to establish a hydration baseline for individual people. Every person has a slightly different electrolyte balance and sweat rate, which the patch will pick up on over time. The more the wearer uses the patch, the better it will be at determining through an algorithm if and when the user is dehydrated.
Self-monitoring is one application, but the device might also tell a trainer to allow an elite athlete to rest, warn a supervisor of an occupational safety concern or notify a fire crew to pull back a firefighter experiencing dangerous levels of dehydration. Thirst, after all, is not always the first sign that someone is not properly hydrated.
The technologies underlying the sweat patch can also be beneficial for patient monitoring in the healthcare space. ABI Research forecasts the market for patient-monitoring wearables, which includes remote and on-site devices, will grow from 8 million shipments in 2016 to 33 million in 2021. Their increasing availability is expected to significantly reduce healthcare costs in a variety of ways.
For example, wearables can help patients and their doctors detect medical conditions like high blood pressure early. They encourage patients to take control — by making fitness goals and tracking their progress, for example — so that they aren’t showing up at the doctor’s office with more serious ailments down the road. And they allow physicians to remotely access a patient’s vitals without an office visit. One estimate shows that wearables and digital apps could save more than $200 billion in healthcare costs over the next 25 years in the United States. “Wearable devices already are having a dramatic impact in changing the healthcare system,” Alizadeh says. “But we believe if you can buy these devices at very low cost like you buy a box of Band-Aids, the impact could be transformative.”
The Air Force has been an eager test subject during the research and development phase. “We are very excited about beginning to demonstrate and realize the impacts that new materials, processing and manufacturing concepts can have on delivering new capabilities to diverse communities of Air Force personnel,” says AFRL scientist and government lead for NBMC Jeremy Ward.
Dr. Malcolm Thompson, executive director of NextFlex, one of the research partners, says that “monitoring the chemistry of humans non evasively is the next frontier of medicine for the chronically sick, warfighters, athlete and that highly stressed premature baby who is so small that you have limited access to sampling their blood. We are very proud to have GE as a member and partner in this major milestone in medical care which saves lives and reduces medical costs,” Thompson says.