New wearable device offers real-time blood pressure monitoring

Seoul National University College of Engineering announced that a research team led by Professor Seung Hwan Ko of the Wearable Soft Electronics Lab, Department of Mechanical Engineering, has developed a wearable electronic device that attaches to the skin like a bandage and enables real-time, continuous monitoring of blood pressure over extended periods.

Unlike conventional cuff-based blood pressure monitors that use an inflatable air bladder to apply pressure to the arm, this new technology continuously measures blood pressure with a compact, flexible electronic patch, garnering global attention for its convenience and innovative design.

Supported by SNU-Global Excellence Research Center establishment project, this collaborative study was conducted jointly with Carnegie Mellon University (U.S.) and has been published in the online edition of Advanced Functional Materials (Impact Factor 19.0, top 4.9% in JCR for Materials Science).

Globally, only 21% of the estimated 1.3 billion people with hypertension effectively manage the condition, posing a major public health concern. However, the cuff-based blood pressure measurement method currently in widespread use is limited to one-time measurements, making continuous measurement difficult. In addition, the size of the cuff causes discomfort, making it unsuitable for long-term blood pressure monitoring during daily life. Additionally, Measurement inaccuracies can also occur due to improper positioning or stress-induced changes during use.

Such limitations prevent detection of dynamic blood pressure changes linked to individual health status and lifestyle, which hinders early diagnosis and prevention of cardiovascular diseases. There is an urgent need for new technologies that allow patients to comfortably measure their blood pressure continuously by simply attaching a device to the skin.

The research team that tackled this problem devised a continuous blood pressure monitoring technology based on the observation that the time it takes for electrical signals (electrocardiogram) and mechanical signals (pulse) generated simultaneously in the heart to reach the wrist varies depending on blood pressure. Electrical signals are transmitted rapidly throughout the body as soon as the heart beats, so they are detected almost immediately at the wrist. On the other hand, mechanical signals are delayed in transmission as blood is pushed out during heart contraction, so it takes some time for the wrist skin to move slightly after the heart beats.

This time difference is directly related to blood pressure. When blood pressure is high, blood flow speed increases, shortening the time difference between the two signals. Conversely, when blood pressure is low, the time difference lengthens. Based on this principle, the research team implemented a model that continuously measures systolic and diastolic blood pressure by precisely detecting the two signals with each heartbeat and analyzing the results.

However, it is not easy to detect subtle changes in the skin caused by blood flow. Therefore, the research team took the next step and designed 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 even at room temperature and conducts electricity well, is suitable as a material for this electronic device because it has the same elasticity as skin.

However, liquid metal has very high surface tension, making it extremely difficult to draw circuits precisely or create fixed shapes. To overcome this limitation, the research team devised a unique process called "laser sintering." By using this method, which involves heating finely dispersed liquid metal particles with a laser to fuse them together, it is possible to draw circuits only at specific desired locations. Finally, the research team successfully developed a wearable electronic device for continuous blood pressure measurement that possesses excellent electrical conductivity and is easily deformable, without the need for additional chemicals, using this process.

This electronic device has excellent electrical and mechanical performance, enabling it to accurately measure both electrocardiograms and heart rates originating from the heart. In addition, the research team confirmed through experiments that the device maintains its performance even when stretched to 700% of its original length or repeatedly stretched more than 10,000 times. Furthermore, they successfully measured the rapid rise and recovery of blood pressure before and after actual exercise, demonstrating more precise blood pressure monitoring capabilities than the existing cuff method.

The continuous blood pressure measurement wearable electronic device developed in this study is expected to revolutionize the way we manage our health in our daily lives. Simply attaching it to the wrist allows real-time monitoring of blood pressure changes, eliminating the inconvenience of having to measure blood pressure only at hospitals or static locations as before. Especially for patients with chronic conditions like hypertension, often referred to as a "silent killer," this electronic device provides practical assistance by enabling them to monitor their current condition anytime and anywhere.

It can also track sudden changes or recovery in blood pressure during exercise, making it useful for personalized exercise prescriptions and fitness coaching. Furthermore, it has industrial potential as a core technology that can be integrated into various types of wearable devices, such as smartwatches, patch-type medical devices, and breathable clothing-type sensors. In the long term, it is expected to contribute to accelerating the arrival of a smart healthcare era where anyone can prevent diseases and manage their health in everyday settings rather than in hospitals.

Professor Seung Hwan Ko, who led the study, commented, "This research challenges the conventional belief that blood pressure measurement is inconvenient and sufficient only once a day. Our system proposes a new healthcare interface capable of detecting and analyzing physiological signals noninvasively and in real time." He added, "Given its potential applications in intensive care monitoring, workplace safety, and lifestyle health data analytics, this technology could become a practical tool for improving quality of life in the modern era."

Co–first authors Jung Jae Park and Sangwoo Hong are working on follow-up research to further advance biosignal-based smart sensor technology based on this study. The two researchers plan to continue their research to enhance the practicality and expandability of this technology by integrating various substrate materials, wireless communication functions, and AI-based data analysis technology.