Professor Ko Seung-hwan's research team at the Department of Mechanical Engineering in Seoul National University developed a wearable electronic device that can be attached to the skin like a bandage to measure blood pressure in real time. The research results were published in the international journal Advanced Functional Materials last June.
There are about 1.3 billion hypertension patients worldwide. Of these, only 21% properly track their blood pressure. The low rate is due to the inefficiency of the traditional cuff method used for measuring blood pressure. The cuff method involves wrapping an air pocket around the arm, applying pressure, and then measuring blood pressure. However, the measurement is one-time, making continuous monitoring difficult, and if patients take measurements in an inaccurate position or feel psychologically tense, the accuracy of the measurements can decrease.
The research team devised continuous blood pressure monitoring technology based on the observation that the time it takes for electrical signals (electrocardiograms) and mechanical signals (pulses) generated simultaneously by the heart to reach the wrist varies with blood pressure. The electrical signals are rapidly transmitted throughout the body at the moment the heart beats, allowing them to be detected almost immediately at the wrist. In contrast, mechanical signals are delayed in transmission as blood is pushed through the arteries during heart contractions, taking some time until the wrist skin slightly moves after the heart beats.
This time difference is directly related to blood pressure. When blood pressure is high, blood flow speeds up, shortening the time difference between the two signals, whereas when blood pressure is low, the difference lengthens. Based on this principle, the research team implemented a model that accurately detects both signals with every heartbeat and analyzes the results to continuously measure systolic and diastolic blood pressure.
Capturing the subtle changes in the skin that occur with blood flow is not easy. Therefore, as the next step, the research team devised an electronic device that naturally adheres to the patient's skin using a unique material called liquid metal. Liquid metal, which remains in a liquid state at room temperature and conducts electricity well, also has the property of stretching like skin, making it suitable as the material for this electronic device.
To draw circuits precisely with liquid metal, the research team developed an original method called 'laser sintering.' By momentarily heating finely dispersed liquid metal particles with a laser to fuse them together, they were able to draw circuits only at specific desired locations.
The developed electronic device excels in both electrical and mechanical performance, allowing for precise measurement of both electrocardiograms and pulses derived from the heart. The research team also confirmed through experiments that the device maintains its performance even when stretched up to 700% of its original length or when stretched more than 10,000 times. Additionally, they successfully measured the rapid increase and recovery process of blood pressure that occurs before and after actual exercise.
Professor Ko Seung-hwan, who led the research, noted, "This research achievement will change the existing perception that measuring blood pressure is cumbersome and that once a day is sufficient," adding, "Especially, its significance lies in presenting a healthcare interface that can detect and interpret physiological signals in real time in daily life using a non-invasive method."
References
Advanced Functional Materials (2025), DOI : https://doi.org/10.1002/adfm.202505089