Cuffless Blood Pressure Monitoring via Ultrasonic Sensor

A recent breakthrough in health monitoring technology has been reported, showcasing a novel ultrasonic sensor developed by Dr. Shin Hur's team at the Korea Institute of Machinery and Materials (KIMM). This innovative device allows for cuffless, non-invasive blood pressure measurement by employing ultrasonic waves to monitor real-time alterations in vascular diameter without the use of traditional cuffs.

Overview of the Technology

This research has been published in the journal Microsystems & Nanoengineering, representing a significant advancement in medical monitoring devices. The team, including researcher Syed Turab Haider Zaidi and in collaboration with Dr. Byung-Chul Lee’s group from the Korea Institute of Science and Technology (KIST), has engineered the first skin-attachable non-invasive blood pressure sensor utilizing single-crystal piezoelectric composites.

Mechanism of the Ultrasonic Sensor

The sensor utilizes a tin–bismuth low-temperature solder bonding technique that integrates high-performance piezoelectric devices onto a flexible substrate. The innovative design consists of a 5×4 ultrasonic transducer array (UTA), enabling efficient blood pressure measurement through the following operational principles:

• The sensor transmits ultrasonic beams that penetrate the skin and collect echoes reflected from blood vessel walls.
• It processes these reflected signals to compute real-time changes in blood vessel diameter, allowing the device to derive systolic and diastolic blood pressure values.

The sensor, built on a flexible polyimide (PI) substrate and encapsulated with Parylene-C, achieves a total thickness under 0.5 mm and weighs less than 1 g, ensuring comfort and adaptability for long-term use.

Advantages Over Traditional Technologies

Traditional blood pressure measurement methods are often vulnerable to external influences such as skin color, movement, and ambient light. Additionally, they typically measure blood vessels located only near the skin's surface. In contrast, this ultrasonic technology provides several advantages:

1. Direct Measurement: Capable of assessing diameter changes in deeper blood vessels.
2. Enhanced Wearability: Unlike previous rigid PZT sensors, the PMN-PT composite is designed for conformal attachment on curved skin surfaces.
3. Simplified Structure: Eliminates the need for additional acoustic matching layers, thus improving manufacturing processes and efficiency.
4. High Accuracy: Achieves measurements within ±4 mmHg, significantly enhancing reliability over conventional methods.

Validation of the Sensor

The validation process involved utilizing an artificial-skin vascular phantom to ensure the accuracy of the new sensor. The findings indicated measurement errors of:

These results align with the AAMI clinical standard of ±5 mmHg, showcasing one of the highest accuracy levels for non-invasive ultrasonic blood pressure monitoring systems to date.

Future Potential and Applications

Dr. Shin Hur remarked on the innovative nature of this technology, stating, “This technology is the first to demonstrate continuous, cuff-free blood pressure monitoring using a skin-attachable ultrasonic sensor.” The promising implications of this research indicate that, when combined with other health monitoring technologies, it could evolve into a key platform for predicting cardiovascular diseases and enhancing smart healthcare solutions.

In conclusion, the development of this ultrasonic sensor not only marks a significant technological advancement in non-invasive health monitoring but also opens new avenues for creating user-friendly and effective health management devices.

References

Zaidi, S. T. H., et al. (2026). Skin-conformal PMN-PT ultrasonic sensor for cuffless blood pressure sensing via eutectic solder integration. Microsystems & Nanoengineering. Retrieved from Phys.org