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Sensitivity improvement of subharmonic-based pressure measurement using phospholipid-coated monodisperse microbubbles
Pengcheng Wang1, Chunjie Tan1, Xiang Ji2
1School of Sensing Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China.
Ultrasonics Sonochemistry
|March 3, 2024
Summary
Monodisperse microbubbles significantly enhance ultrasound-based blood pressure measurement sensitivity. Using uniform microbubbles improves subharmonic signal consistency and measurement accuracy for clinical applications.
Area of Science:
- Biomedical Engineering
- Acoustic Physics
Background:
- Non-invasive blood pressure measurement using ultrasound and microbubbles is promising.
- Current microbubble limitations include wide size distribution and diverse shell properties, reducing measurement sensitivity.
- Improving microbubble uniformity is key to enhancing subharmonic-based pressure sensing.
Purpose of the Study:
- To investigate the use of monodisperse microbubbles for improved sensitivity in ultrasound-based blood pressure measurements.
- To compare the subharmonic response of monodisperse versus polydisperse microbubbles to ambient overpressure.
- To optimize ultrasound parameters for maximal subharmonic emission from monodisperse microbubbles.
Main Methods:
- Fabrication of monodisperse and polydisperse microbubbles using microfluidics and mechanical agitation.
- Systematic variation of ultrasound parameters: frequency, peak negative pressure (PNP), and pulse length.
- Analysis of subharmonic amplitude response to varying ambient overpressure for both microbubble types.
Main Results:
- Monodisperse microbubbles exhibited an optimal excitation frequency (2.8 MHz) for subharmonic emission, unlike polydisperse ones.
- Three distinct response regimes (occurrence, growth, saturation) were observed with increasing PNP.
- Monodisperse microbubbles showed a monotonic decrease in subharmonic amplitude with overpressure, enabling higher sensitivity.
- Achieved a ~6.5 times higher maximum sensitivity (1.18 dB/kPa) with monodisperse microbubbles compared to polydisperse (0.18 dB/kPa).
Conclusions:
- Monodisperse microbubbles provide a more consistent subharmonic signal response to ambient pressure changes.
- The use of uniform microbubbles significantly enhances the sensitivity and reliability of ultrasound-based non-invasive blood pressure monitoring.
- This advancement holds potential for more accurate clinical blood pressure assessments.
