A pioneering ultrasonic technology has emerged, facilitating cuffless, non-invasive blood pressure monitoring by tracking real-time changes in vascular diameter. The innovation promises to be a foundational element in forthcoming wearable healthcare devices and smart medical monitoring systems.
The groundbreaking development is attributed to a research team led by Dr. Shin Hur at the Korea Institute of Machinery and Materials (KIMM), with contributions from Syed Turab Haider Zaidi of the UST–KIMM School, in collaboration with Dr. Byung-Chul Lee’s team at the Korea Institute of Science and Technology (KIST). This team has engineered the first skin-attachable, non-invasive blood pressure sensor utilising PMN-PT single-crystal piezoelectric composites through a low-temperature soldering process.
The sensor employs a dual-side SnBi low-temperature solder bonding technique to integrate high-performance piezoelectric devices onto a flexible substrate, avoiding depolarisation. The fabricated ultrasonic transducer array (UTA) penetrates the skin with an ultrasonic beam, detecting signals from vessel walls to measure changes in vessel diameter. This method accurately calculates blood pressure values corresponding to systolic and diastolic phases. Constructed on a flexible polyimide substrate with Parylene-C encapsulation, the sensor adheres securely to the skin, maintaining a thickness under 0.5 mm and a weight below 1 g for prolonged wearability.
The sensor’s operation involves transmitting ultrasound generated by PMN-PT single-crystal composites into blood vessels. Reflected echoes are analysed to measure vascular diameter and calculate blood pressure. Multi-physics simulations using COMSOL were conducted to optimise acoustic propagation and reflection. The low-temperature soldering method, operating below 150 °C, prevents thermal depolarisation in lead-based piezoelectric devices, ensuring high signal-to-noise ratio and electrical bonding reliability.
Current optical cuffless blood pressure measurement technologies suffer from environmental susceptibility and limitations to surface-level vessels. In contrast, this ultrasound-based technology measures actual diameter changes in deeper vessels beneath the skin. The PMN-PT composite, combined with low-temperature soldering, ensures conformal attachment to curved surfaces without performance degradation. The sensor offers high accuracy within ±4 mmHg and skin-attachable flexibility, surpassing existing technologies.
Validation was achieved using an artificial-skin vascular phantom, demonstrating measurement errors of ±4 mmHg for systolic and ±2.3 mmHg for diastolic pressures, meeting the AAMI clinical standard of ±5 mmHg. This accuracy is among the highest reported for non-invasive ultrasonic blood pressure monitoring.
Dr. Shin Hur stated, “This technology is the first to demonstrate continuous, cuff-free blood pressure monitoring using a skin-attachable ultrasonic sensor. Combined with AI-based blood pressure analysis, it will evolve into a core platform for personalised cardiovascular disease prediction and smart healthcare.”
The development was supported by the Ministry of Trade, Industry, and Resources’ Materials and Components Technology Development Program. The research is documented in the January 2026 edition of Microsystems & Nanoengineering, a leading journal in the Instruments & Instrumentation category.
