Wearable patch monitors patients with heart disease
Engineers at the University of California San Diego have developed the first polyester wearable device capable of monitoring both biochemical and electric signals in the human body
The Chem-Phys patch records electrocardiogram (EKG) 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, communicates wirelessly with a smartphone, smart watch or laptop and according to the University of California San Diego, could be used to help physicians monitor patients with heart disease.
Nanoengineers and electrical engineers at the UC San Diego Center for Wearable Sensors worked together to build the device that wirelessly transmits the data from biochemical and electrical signals via bluetooth.
Joseph Wang, a nanoengineering professor and electrical engineering professor Patrick Mercier at the UC San Diego Jacobs School of Engineering led the project.
Mercier said: “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. 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, with almost none of them measure chemical signals, such as lactate.
The ChemPhys patch is the first wearable sensor capable of monitoring both biochemical and electric signals in the human body. The patch consists of a custom-made board and screen-printed 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 EKG electrodes bracketing it to the left and the right.
Researchers had to make sure the EKG 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 EKG measurements.
To avoid this, 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 EKG electrodes, but not the lactate sensor, according to the University of California San Diego.
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.
Kevin Patrick, a physician and director of the Center for Wireless and Population Health Systems at UC San Diego, who was not involved with the research, said: “The ability to sense both EKG and lactate in a small wearable sensor could provide benefits in a variety of areas.
“The ability to concurrently assess EKG and lactate could open up some interesting possibilities in preventing and/or managing individuals with cardiovascular disease."