Science & Technology

A device that uses sweat for real time physiology check

Researchers believe that this technology may be further enhanced for studying patterns and providing personlised medicine

By Aakanksha Varma
Published: Thursday 28 January 2016

A team of scientists has created a health-monitoring device that can provide real-time analysis of a person’s physiological state on their smart phone using their sweat.

Researchers say it is the first fully integrated device that can provide continuous monitoring of multiple biochemicals in sweat. Other sweat-based and non-invasive sensors either monitor only a single molecule at a time or lack signal processing that can adjust for temperature effects or interactions among different molecules.

"Human sweat contains physiologically rich information, thus making it an attractive body fluid for non-invasive wearable sensors,” said study principal investigator Ali Javey, a UC Berkeley professor of electrical engineering and computer sciences in a press release.

Sweat is an easily obtainable bodily fluid that contains a variety of different biomarkers — from simple ions to protein molecules and heavy metals such as cadmium, mercury and arsenic. "However, sweat is complex. So we have developed a system that simultaneously and selectively measures multiple sweat analytes, and wirelessly transmits the processed data to a smart phone,” adds Javey.

Presently, sweat studies collect perspiration off the body in containers and then analyse it in the lab. Sweat is already used to diagnose certain diseases (like cystic fibrosis), to detect drug use and to optimize athletic performance. However the data used aren’t real-time or continuous.  

Study co-lead authors Wei Gao and Sam Emaminejad worked to develop a prototype that packs five sensors onto a flexible circuit board. The sensors measure the metabolites glucose and lactate, the electrolytes sodium and potassium, and skin temperature.

"The integrated system allows us to use the measured skin temperature to calibrate and adjust the readings of other sensors in real time," said Gao. "This is important because the response of glucose and lactate sensors can be greatly influenced by temperature."

Future Scope for body-monitoring

A paper published in Nature journal describes how the flexible sensors detect the presence of different molecules and ions based on their electrical signals.

“The more glucose or lactate in your sweat, the more electrical current is generated at the sensor’s surface. And the more sodium and potassium, the larger the voltage,” explained Emaminejad. “When your skin temperature goes up, the higher temperature increases the signal from glucose, making it look like you are releasing more glucose in your sweat than you actually are. Thus, it’s important to measure both temperature and molecules at the same time to calibrate the device.”

Researchers believe that future devices will be much smaller and will be able to instantaneously alert users to health problems such as fatigue, dehydration and dangerously high body temperatures. They speculate further on how the technology may evolve. “With continuous, real-time monitoring of populations of people, we’ll be able to study the collected data for patterns that can guide clinically oriented investigations and deliver personalised medicine,” said co-author Ron Davis, professor of biochemistry at Stanford.

George Brooks, a UC Berkeley professor of integrative biology and co-author of the study said, "When studying the effects of exercise on human physiology, we typically take blood samples. With this non-invasive technology, someday it may be possible to know what’s going on physiologically without needle sticks or attaching little, disposable cups on you."

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