Conformal Ultrasonic Device for Non-Invasive Central Blood Pressure Monitoring

An engineering study focused on developing a conformal ultrasonic device using stretchable circuit patterning for non-invasive monitoring of central blood pressure and deep-tissue hemodynamics.

Overview

Developed a soft, skin-conformal ultrasonic patch for continuous, non-invasive monitoring of central blood pressure and deep-tissue hemodynamics. The device maintains signal integrity during natural body motion, enabling real-time cardiovascular monitoring outside clinical settings.

Publication

Wang C, Li X, Hu H, Zhang L, Huang Z, Lin M, Zhang Z, Yin Z, Huang B, Gong H, et al. Monitoring of the central blood pressure waveform via a conformal ultrasonic device. Nature Biomedical Engineering, 2018;2(9):687-695. doi: 10.1038/s41551-018-0287-x

Key Innovation

Challenge: Conventional blood pressure monitoring is intermittent (cuff-based) or invasive (catheter-based), failing to capture dynamic cardiovascular changes in real-world conditions.

Solution: A stretchable ultrasound transducer that conforms to curved body surfaces (neck, chest) and maintains acoustic coupling during motion.

Technical Features

Device Architecture

  • Stretchable circuitry: Copper-polyimide flexible electrodes
  • Soft substrate: Elastomeric material for skin conformability
  • Piezoelectric transducer: Laser micro-cut for precision
  • Biocompatible encapsulation: Silicone-based protective layer

Key Capabilities

  • Continuous arterial pulse monitoring
  • Central blood pressure waveform reconstruction
  • Maintains performance during body motion
  • Non-invasive deep-tissue imaging

Validation Results

Clinical Accuracy

  • Successfully measured carotid artery and internal jugular vein pulsations
  • Waveform quality comparable to rigid clinical ultrasound probes
  • Stable acoustic coupling under dynamic conditions

Performance Metrics

  • High-fidelity hemodynamic waveforms
  • Accurate pulse transit time measurements
  • Reliable long-term monitoring capability

Clinical Significance

Central blood pressure (at the aorta) is a better predictor of cardiovascular risk than peripheral measurements (arm cuff). This device enables:

  • Continuous monitoring of cardiovascular health
  • Early detection of hemodynamic changes
  • Home-based cardiovascular assessment
  • Personalized medicine through real-time data

Fabrication Process

  1. Circuit patterning: Stretchable copper-polyimide networks
  2. Laser micro-cutting: Precision electrode fabrication
  3. Transducer integration: Piezoelectric element embedding
  4. Elastomer encapsulation: Soft protective coating
  5. Acoustic optimization: Maintained signal transparency

Applications

This wearable ultrasound technology enables:

  • Continuous cardiovascular monitoring for at-risk patients
  • Real-time hemodynamic assessment during exercise
  • Home-based health tracking for chronic conditions
  • Early warning system for cardiovascular events

Impact

This work represents a transformative step toward wearable clinical-grade medical devices, combining:

  • Soft materials engineering
  • Biocompatible electronics
  • Advanced ultrasound imaging
  • Continuous health monitoring

Supervision

Conducted under Prof. Sheng Xu, Department of NanoEngineering, UC San Diego (Xu Research Group).