New look at sweat from the outside in
Wearable device monitors athletes’ body chemistry as they perspire
“Sweat is an interesting body fluid. It is rich with information, filled with chemicals.”
Ali Javey, lead researcher and UC Berkeley professor
Scientists are looking to advance athletic performance using the body’s most ubiquitous response to physical activity: sweat.
A personal health monitoring system created by UC Berkeley and Stanford researchers goes a step beyond popular techniques such as measuring a person’s heartbeats or the number of steps taken.
“Sweat is an interesting body fluid,” said lead researcher Ali Javey, a UC Berkeley professor of electrical engineering and computer sciences. “It is rich with information, filled with chemicals.”
The scientists are particularly interested in electrolytes and metabolites, along with skin temperation ture, that give insight into what’s going on inside an athlete’s body during physical activity, and they have created a flexible, wearable band of sensors to measure it all in real time.
The band senses the composi- of four main compounds in sweat and syncs that information to a smartphone app in real time to let athletes know ahead of time that they are at risk of dehydration, cramping or overheating.
Any one of those is unpleasant news to athletes, caused by the loss of essentials like sodium, potassium or glucose sweated out of the body.
The new technology is designed to provide an athlete information to help understand and get the most out of his or her physical performance, said George Brooks, UC Berkeley professor of integrative biology and co- author of the study.
“If a person is very active, they want to know what their losses are so they can manage the losses and replace what they lose,” Brooks said. “It’s sort of like why we wear the heart rate monitors, so we know the level of effort we put in. This even goes beyond that.”
This technology is the first of its kind that can measure the composition of sweat as it appears on the skin. Scientists historically have only been able to track the body’s fluid composition during workouts through invasive blood samples or bothersome specialized cups attached to the body, which would both have to be sent off to the lab for time- consuming analysis.
“Historically it has been difficult to perform sweat analysis,” Javey said. “The nice thing about the sensor system is it’s very comfortable to wear and doesn’t need much sweat: just onetenth of a droplet to work.”
The band of sensors measures the amounts of sodium, potassium, lactate and glucose in sweat because levels of those compounds have been shown to be indicative of physical health.
For example, they said sodium and potassium levels could indicate dehydration or muscle cramps, lactate levels could warn of blood flow problems, glucose could track blood sugar levels and skin temperature could show overheating.
Researchers tested their wearable sensors on 26 men and women who exercised on indoor stationary bikes or on outdoor tracks and trails. Someday, they said, it could be used to remotely monitor people for an array of health conditions and not just to track and improve fitness.
“In the future I imagine that we will all have devices like this to measure a range of different things,” Brooks said. “There are many medical applications.”
The researchers hope to conduct a large- scale study of their device on volunteers to allow them a better understanding of what levels of various molecules in sweat mean for physical fitness and general human health, Javey said. They have filed a patent on their work, but he said they are not currently collaborating with anyone to commercialize their technology.
“This is just academ-icbased research for proof of concept, so it would be up to a company to apply this technology and put it into a product,” Javey said. “But we do hope our technology could eventually be translated into a product sometime in the future.”
The researchers detailed their work in a study published Jan. 27 in the journal Nature. Kevin Schultz is a San Francisco Chronicle staff writer. E- mail: kschultz@ sfchronicle. com Twitter: @ KevinEdSchultz