Local researchers said they have developed an electronic patch that can check health by monitoring sweat.
On Thursday, the Korea Advanced Institute of Science and Technology (KAIST) said Professor Kwon Kyeong-ha of the Electrical Engineering Department and Professor Kim Jong-uk of Chemical Engineering Department at Sungkyunkwan University developed a wireless electronic patch that measures the volumetric flow and total loss of sweat in real-time.
To collect sweat easily as biomarkers, one has to use the discoloration that appears in reaction with chemical reagents. To do so, one has to measure sweat flow rate and accumulative loss in real-time.
The research team developed a wearable, wireless, electronic patch that can monitor sweat flow rate and sweat loss. Using the discoloration, the platform was integrated with microfluidic systems to analyze the sweat components.
To monitor the sweat release rate in real-time, the researchers designed a “thermal flow sensing module.” They made a sophisticated microfluidic channel to allow the collected sweat to flow through a narrow passage and put a heat source on the outer surface of the channel to induce heat exchange between the sweat flowing inside the channel and the heated channel.
As a result, the researchers could develop a wireless electronic patch that can measure the temperature difference in a specific location upstream and downstream of the heat source with an electronic circuit and convert it into a digital signal to measure the sweat release rate in real-time.
The patch accurately measured the perspiration rate in the range of 0-5 microliters/minute (μl/min), which was considered physiologically significant, the KAIST said.
The research team successfully measured chloride, glucose, creatine concentration, pH, and volumetric flow rate in sweat. The research team said these indicators could be used to diagnose cystic fibrosis, diabetes, kidney dysfunction, and metabolic alkalosis.
As the sweat flowing in the microfluidic channel was completely separated from the electronic circuit, the new patch overcame the shortcomings that existing flow rate measuring devices were vulnerable to corrosion and aging.
The patch can be easily attached to the skin with a flexible circuit board printing technology and silicone sealing technology and has a sensor that detects changes in skin temperature.
Using a smartphone app, a user can check data, measured by the wearable patch, in real-time.
“The wireless electronic patch can be widely used for personal hydration strategies, detection of dehydration symptoms, and other health management purposes,” Kwon said.
The patch can also be used in a systematic drug delivery system, such as measuring the blood flow rate in blood vessels near the skin surface or measuring the drug release rate in real-time to calculate the exact dosage, he added.
The KAIST said it was seeking the technology patent with John Rogers, a professor at the Northwestern University, and Wearifi, a wearables developer in Boston, the U.S.
The study was published in Natures Electronics, with the title, “An on-skin platform for wireless monitoring of flow rate, cumulative loss, and temperature of sweat in real-time” in March.