San Diego – A research team at the University of California, San Diego, has developed a tiny flexible patch that’s worn on a user’s chest to monitor sweat and heart rate while working out. Scientists claim that the Chem-Phys is the first wearable gadget to track both biochemical signals and electrical heart markers, according to a paper published Wednesday in the journal Nature Communications.

The researchers said the Chem-Phys is able to monitor the user’s electrocardiogram heart signals and the levels of lactate, which decrease as they work out. The data recorded in a trial of the prototype was transmitted to a mobile app and then compared with data obtained by other fitness trackers.

Chem-Phys is a hybrid sensing system wore on user's chest
The researchers claim that the Chem-Phys is the first wearable gadget to track both biochemical signals and electrical heart markers. Credit:

The tiny patch has three sensors built on a two-inch polyester sheet. One of them detects lactate from sweat and the other two capture heart rate. The device sends the data to a nearby computer via Bluetooth thanks to a lithium-ion battery-powered chip built on the patch.

“We introduce a skin-worn wearable hybrid sensing system that offers simultaneous real-time monitoring of a biochemical (lactate) and an electrophysiological signal (electrocardiogram), for more comprehensive fitness monitoring than from physical or electrophysiological sensors alone,” the paper reads.

The team tested the Chem-Phys during 30-minute workouts. It recorded heart rate data which closely matched the electrocardiogram’s readings. The researchers have plans to investigate whether the same wearable gadget can be used to track other vital signs.

The patch is so small that it wasn’t easy for the scientists to ensure that the biochemical signals didn’t interfere with the electrical heart markers, as they explained in Nature Communications. They placed the EKG electrodes about 1.5 inches from the lactate sensor in the middle to reduce risks of cross-talk in the circuits.

The importance of hybrid systems

The researchers remarked in the paper the importance of the development of hybrid systems given the complexity of the human body. They say a wide variety of factors occur during intense physical activity and noted that keeping track of physiologic effects taking place while working out can benefit athletes, the elderly and many other people.

Study authors recommend the realization of further research in the field of wearable sensors by developing new sensing modalities in order to integrate them with the existing ones and provide a complete information. The idea, they say, is to create devices that allow users to have real-time access to a wider range of parameters that are relevant to performance states, diseases and health conditions. Researchers pointed out that it’s not enough to conduct infrequent tests in clinical labs, which is why they focus on a continuous, multimodal sensor fusion to better understand a person’s well-being.

Other recent research on wearable trackers

The paper released on Nature Communications mentioned a Gao et al test which demonstrated a wearable patch capable of simultaneously monitoring levels of electrolytes and metabolites found in human sweat. However, study authors noted that the device lacks electrophysiology sensors that could help it become a multimodal sensor.

A separate team led by Ali Javey of UC Berkley created in January a small flexible gadget that uses a printed plastic sensor array to track lactate, glucose, sodium, potassium and body temperature. Another team based at the University of Cincinnati in Ohio has also been working on wearable sweat sensors.

Source: Nature Communications