Star Trek fans will be familiar with the tricorder – a device used in the fictional TV series to scan and gather detailed information about places and living things. Now, researchers have brought the technology to the real world, creating a wearable, tricorder-like device that can measure biochemical and electrical signals in the human body simultaneously.
The device – called the “Chem-Phys patch” – measures real-time levels of lactate, a biochemical that serves as an indicator of physical activity, as well as the heart’s electrical activity.
Put simply, the novel technology monitors a person’s fitness levels and heart function at the same time, and it is the first device that can do so.
“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,” says co-project leader Patrick Mercier, of the Jacobs School of Engineering at the University of California-San Diego.
“This research represents an important first step to show this may be possible.”
Mercier and colleagues reveal how the device was created and how it works in a study published in Nature Communications.
According to the team, the majority of wearable fitness trackers currently on the market only have the ability to measure one body signal at a time, such as the number of steps taken or heart rate.
Furthermore, almost none of them have the ability to measure chemical signals, such as lactate.
Mercier and colleagues set out to address this gap in the field by creating a wearable sensor that can simultaneously measure electrical and biochemical body signals.
The Chem-Phys patch is made of a thin, adhesive, flexible sheet of polyester, which the researchers manufactured using screen printing.
A lactate-sensing electrode is situated in the center of the patch, and two electrocardiogram (EKG) electrodes – which sense the heart’s electrical signals – are situated either side.
The main challenge the team faced was ensuring that the signals from each electrode did not interfere with each other, which could skew the results.
The researchers placed the electrodes at various distances from each other and tested which distance best avoided interference. They found that a distance of 4 centimeters – around 1.5 inches – between the EKG electrodes provided the best quality signal.
Additionally, the researchers needed to ensure the EKG sensors were entirely separate from the lactate sensor; because the lactate sensor works with the help of a small voltage, which can pass through sweat, it has the potential to disrupt EKG readings.
To make sure sweat only comes into contact with the lactate sensor, avoiding the EKG electrodes, a soft, water-repellent silicone rubber was added to the device.
Next, the researchers connected each sensor to a small, custom-printed circuit board. This consists of a microcontroller and a Bluetooth low energy chip, which send the information gathered by the device to a smartphone, smartwatch, or laptop.
For their study, Mercier and colleagues tested the Chem-Phys patch on three men as they engaged in 15-30 minutes of intense cycling.
All three men wore the patch on their chest, near the base of their sternum, and two of the men also wore a commercial heart rate monitor on their wrist.
The researchers found that the data collected by the EKG electrodes closely matched the data collected by the commercial heart rate monitor.
Furthermore, they found that the information gathered by the lactate sensor closely matched lactate data collected during increasing physical activity in previous studies.
Based on their results, the researchers believe their Chem-Phys patch brings closer the possibility of a wearable fitness device that simultaneously measures a variety of body signals.
The researchers say their device could prove useful in a number of areas.
“There would certainly be interest in the sports medicine community about how this type of sensing could help optimize training regimens for elite athletes.
The ability to concurrently assess EKG and lactate could also open up some interesting possibilities in preventing and/or managing individuals with cardiovascular disease.”
Dr. Kevin Patrick, University of California-San Diego