New Ultrasonic Technology for Cuffless Blood Pressure Monitoring Developed
A research team, including Dr. Shin Hur at the Korea Institute of Machinery and Materials (KIMM) and Dr. Byung-Chul Lee's team at the Korea Institute of Science and Technology (KIST), has developed a skin-attachable, non-invasive blood pressure sensor. This technology utilizes ultrasonic waves to track real-time changes in vascular diameter, eliminating the need for a traditional blood pressure cuff.
Sensor Design and Functionality
The sensor incorporates PMN-PT (Lead Magnesium Niobate–Lead Titanate) single-crystal piezoelectric composites, integrated onto a flexible substrate using a low-temperature soldering process. A dual-side tin–bismuth (SnBi) low-temperature solder bonding technique was applied to prevent depolarization during integration. The sensor is an ultrasonic transducer array (UTA) with a 5x4 array structure. It transmits ultrasonic beams into the skin, detects signals reflected from vessel walls, and measures changes in vessel diameter to calculate real-time systolic and diastolic blood pressure.
Constructed on a flexible polyimide (PI) substrate with a Parylene-C encapsulation layer, the sensor adheres to human skin. Its total thickness is less than 0.5 mm, and it weighs under 1 gram, designed for extended wearability.
Technical Advantages
The team conducted multi-physics simulations using COMSOL to optimize acoustic propagation. The low-temperature soldering method, conducted below 150 °C, addresses thermal depolarization common in lead-based piezoelectric devices, maintaining a high signal-to-noise ratio (SNR) and electrical bonding reliability.
This ultrasonic method offers advantages over existing optical cuffless blood pressure measurement technologies, which are susceptible to external factors like skin color, movement, and lighting, and are limited to superficial blood vessels. The developed ultrasonic sensor can measure diameter changes in deeper blood vessels. Unlike traditional rigid PZT ultrasonic sensors, the PMN-PT composite, combined with low-temperature soldering, allows for conformal attachment to curved skin surfaces without performance degradation. The simplified structure achieves high SNR without requiring acoustic matching or backing layers, improving manufacturing efficiency.
Validation and Accuracy
The sensor's accuracy was validated using an artificial-skin vascular phantom. Measured systolic blood pressures showed an error of ±4 mmHg, and diastolic pressures had an error of ±2.3 mmHg. These results meet the AAMI clinical standard of ±5 mmHg for non-invasive blood pressure monitoring.
Future Applications
The developers state that this technology represents a continuous, cuff-free blood pressure monitoring system using a skin-attachable ultrasonic sensor. They anticipate its integration with AI-based blood pressure analysis, forming a core platform for personalized cardiovascular disease prediction and smart healthcare.
Funding and Publication
This development was supported by the Ministry of Trade, Industry and Resources' Materials and Components Technology Development Program. The research was published in January 2026 in Microsystem & Nanoengineering under the title "Skin-Conformal PMN-PT Ultrasonic Sensor for Cuffless Blood Pressure Sensing via Eutectic Solder Integration."