Samsung funds research into wearable to measure biochemical and electrical signals
June 14, 2016
Samsung has funded research into a flexible wearable device that can monitor both biochemical and electric signals in the human body. Developed by engineers at the University of California San Diego, the Chem-Phys patch records electrocardiogram (ECG) heart signals and tracks levels of lactate, a biochemical that is a marker of physical effort, in real time.
The device can be worn on the chest and communicates wirelessly with a smartphone, smart watch or laptop. It could have a wide range of applications, from athletes monitoring their workouts to physicians monitoring patients with heart disease.
Nanoengineers and electrical engineers at the UC San Diego Center for Wearable Sensors worked together to build the device, which includes a flexible suite of sensors and a small electronics board. The device can also transmit the data from biochemical and electrical signals via Bluetooth.
Nanoengineering professor Joseph Wang and electrical engineering professor Patrick Mercier at the UC San Diego Jacobs School of Engineering led the project, with Wang’s team working on the patch’s sensors and chemistry, while Mercier’s team worked on the electronics and data transmission.
“One of the overarching goals of our research is to build a wearable tricorder-like device that can measure simultaneously a whole suite of chemical, physical and electrophysiological signals continuously throughout the day,” Mercier said. “This research represents an important first step to show this may be possible.”
Most commercial wearables only measure one signal, such as steps or heart rate, Mercier said. Almost none of them measure chemical signals, such as lactate.
That is the gap that the sensor designed by researchers at the Jacobs School of Engineering aims to bridge. Combining information about heart rate and lactate – a claimed first in the field of wearable sensors – could be especially useful for athletes wanting to improve their performance. Both Mercier and Wang have been fielding inquiries from Olympic athletes about the technologies the Center for Wearable Sensors produces.
“The ability to sense both ECG and lactate in a small wearable sensor could provide benefits in a variety of areas,” said Kevin Patrick, a physician and director of the Center for Wireless & Population Health Systems at UC San Diego. “There would certainly be interest in the sports medicine community about how this type of sensing could help optimise training regimens for elite athletes. The ability to concurrently assess ECG and lactate could also open up some interesting possibilities in preventing and/or managing individuals with cardiovascular disease."
The researchers’ biggest challenge was making sure signals from the two sensors didn’t interfere with each other. This required some careful engineering and a fair bit of experimentation before finding the right configuration for the sensors.
Researchers used screen printing to manufacture the patch on a thin, flexible polyester sheet that can be applied directly to the skin. An electrode to sense lactate was printed in the centre of the patch, with two ECG electrodes bracketing it to the left and the right. Engineers went through several iterations of the patch to find the best distance between electrodes to avoid interference while gathering the best quality signal. They found that a distance of four centimetres between the ECG electrodes was optimal.
Researchers also had to make sure the ECG sensors were isolated from the lactate sensor. The latter works by applying a small voltage and measuring electric current across its electrodes. This current can pass through sweat, which is slightly conductive, and can potentially disrupt ECG measurements. So the researchers added a printed layer of soft water-repelling silicone rubber to the patch and configured it to keep the sweat away from the ECG electrodes, but not the lactate sensor.
The sensors were then connected to a small custom printed circuit board equipped with a microcontroller and a Bluetooth Low Energy chip, which wirelessly transmitted the data gathered by the patch to a smartphone or a computer.
The patch was tested on three male subjects, who wore the device on their chest, near the base of their sternum, while doing 15 to 30 minutes of intense activity on a stationary bike. Two of the subjects also wore a commercial wristband heart rate monitor. The data collected by the ECG electrodes on the patch closely matched the data collected by the commercial wristband. The data collected by the lactate biosensor followed closely data collected during increasing intensity workouts in other studies.
Next steps include improving the way the patch and the board are connected and adding sensors for other chemical markers, such as magnesium and potassium, as well as other vital signs. Physicians working with Wang and Mercier are also excited about the possibility of analysing the data from the two signals and see how they correlate.
Funding came from the National Institute of Biomedical Imaging & Bioengineering at the National Institutes of Health, Samsung and the Arnold & Mabel Beckman Foundation.
• Samsung Electronics has unveiled the Gear Fit2 and the Gear IconX consumer fitness devices.
The Gear Fit2 has an embedded GPS and a heart rate monitor that provide accurate and robust fitness tracking and measurement, while providing instant feedback on the user’s workout. The Gear IconX are cord-free earbuds that can track fitness information and provide users with feedback on their running performance.
“Living a healthy lifestyle is a top priority for consumers to enjoy fulfilling lives,” said Younghee Lee, executive vice president at Samsung Electronics. “Our wearable technology can enhance existing routines and blend fitness and fun. The Gear Fit2 and Gear IconX are specialised to easily address these needs, ultimately allowing users to get more out of their fitness experiences and everyday activities.”