Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles

This study presents an experimental investigation of the influence of MB concentration on the resonance frequency of lipid-coated microbubbles (MBs). Expanding on theoretical models and numerical simulations from previous research, this work experimentally investigates the effect of MB size on the r...

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Main Authors: Hossein Haghi, Mahshid Yaali, Agata A. Exner, Michael C. Kolios
Format: Article
Language:English
Published: Elsevier 2025-01-01
Series:Ultrasonics Sonochemistry
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Online Access:http://www.sciencedirect.com/science/article/pii/S135041772400419X
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author Hossein Haghi
Mahshid Yaali
Agata A. Exner
Michael C. Kolios
author_facet Hossein Haghi
Mahshid Yaali
Agata A. Exner
Michael C. Kolios
author_sort Hossein Haghi
collection DOAJ
description This study presents an experimental investigation of the influence of MB concentration on the resonance frequency of lipid-coated microbubbles (MBs). Expanding on theoretical models and numerical simulations from previous research, this work experimentally investigates the effect of MB size on the rate of resonance frequency increase with concentration, a phenomenon observed across MBs with two different lipid compositions: propylene glycol (PG) and propylene glycol and glycerol (PGG). Employing a custom-designed ultrasound attenuation measurement setup, we measured the frequency-dependent attenuation of MBs, isolating MBs based on size to generate distinct monodisperse sub-populations for analysis. The resonance frequency of MBs was determined by identifying the attenuation peak in the broadband attenuation ultrasound attenuation measurements. Our experimental findings confirm that larger MBs (≈2.1μm) demonstrate a more significant shift in resonance frequency (≈ 5 MHz, ≈ 40%) as a function of MB concentration. In contrast, smaller MBs (≈1.3μm) show a minor shift in the resonant frequency (≈ 1.8 MHz, ≈ 8%), underlining the importance of size in determining acoustic behavior compared to changes in the lipid shell properties. Additionally, we observed that resonance frequency increase with concentration reaching a saturation point at higher concentrations. This plateau occurs at higher concentrations for larger MBs (≈2.1μm), while smaller MBs (≈1.6μm and ≈1.3μm) reach this saturation point at lower concentrations. Furthermore, the study highlights the small effect of bubble–bubble interactions on the resonance frequency of MB populations, particularly at lower MB concentrations and for smaller MBs. This insight is important for applications utilizing MB clusters, such as contrast-enhanced ultrasound imaging and MB-mediated therapies. While both size and lipid shell composition influence resonance frequency, MB size has a more significant effect. In conclusion, our findings affirm the need to consider both MB size and concentration when utilizing MBs for clinical and industrial ultrasonic applications.
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spelling doaj-art-00f76bb2a5bf42498a7230afe8117e6f2025-08-20T02:40:15ZengElsevierUltrasonics Sonochemistry1350-41772025-01-0111210717010.1016/j.ultsonch.2024.107170Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubblesHossein Haghi0Mahshid Yaali1Agata A. Exner2Michael C. Kolios3Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario, Canada; Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between St. Michael’s Hospital and Toronto Metropolitan University, 209 Victoria St, Toronto, Ontario, Canada; Corresponding author at: Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario, Canada.Toronto Metropolitan University, 350 Victoria Street, Toronto, Ontario, Canada; Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between St. Michael’s Hospital and Toronto Metropolitan University, 209 Victoria St, Toronto, Ontario, CanadaDepartment of Radiology, Case Western Reserve University, Cleveland, OH, 44106, USAToronto Metropolitan University, 350 Victoria Street, Toronto, Ontario, Canada; Institute for Biomedical Engineering, Science and Technology (iBEST), a partnership between St. Michael’s Hospital and Toronto Metropolitan University, 209 Victoria St, Toronto, Ontario, CanadaThis study presents an experimental investigation of the influence of MB concentration on the resonance frequency of lipid-coated microbubbles (MBs). Expanding on theoretical models and numerical simulations from previous research, this work experimentally investigates the effect of MB size on the rate of resonance frequency increase with concentration, a phenomenon observed across MBs with two different lipid compositions: propylene glycol (PG) and propylene glycol and glycerol (PGG). Employing a custom-designed ultrasound attenuation measurement setup, we measured the frequency-dependent attenuation of MBs, isolating MBs based on size to generate distinct monodisperse sub-populations for analysis. The resonance frequency of MBs was determined by identifying the attenuation peak in the broadband attenuation ultrasound attenuation measurements. Our experimental findings confirm that larger MBs (≈2.1μm) demonstrate a more significant shift in resonance frequency (≈ 5 MHz, ≈ 40%) as a function of MB concentration. In contrast, smaller MBs (≈1.3μm) show a minor shift in the resonant frequency (≈ 1.8 MHz, ≈ 8%), underlining the importance of size in determining acoustic behavior compared to changes in the lipid shell properties. Additionally, we observed that resonance frequency increase with concentration reaching a saturation point at higher concentrations. This plateau occurs at higher concentrations for larger MBs (≈2.1μm), while smaller MBs (≈1.6μm and ≈1.3μm) reach this saturation point at lower concentrations. Furthermore, the study highlights the small effect of bubble–bubble interactions on the resonance frequency of MB populations, particularly at lower MB concentrations and for smaller MBs. This insight is important for applications utilizing MB clusters, such as contrast-enhanced ultrasound imaging and MB-mediated therapies. While both size and lipid shell composition influence resonance frequency, MB size has a more significant effect. In conclusion, our findings affirm the need to consider both MB size and concentration when utilizing MBs for clinical and industrial ultrasonic applications.http://www.sciencedirect.com/science/article/pii/S135041772400419XBubble dynamicsCavitationUltrasoundBubble–bubble interactionMicrobubblesUltrasound contrast agents
spellingShingle Hossein Haghi
Mahshid Yaali
Agata A. Exner
Michael C. Kolios
Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
Ultrasonics Sonochemistry
Bubble dynamics
Cavitation
Ultrasound
Bubble–bubble interaction
Microbubbles
Ultrasound contrast agents
title Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
title_full Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
title_fullStr Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
title_full_unstemmed Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
title_short Experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
title_sort experimental investigation on the effect of concentration on the resonance frequency of lipid coated ultrasonically excited microbubbles
topic Bubble dynamics
Cavitation
Ultrasound
Bubble–bubble interaction
Microbubbles
Ultrasound contrast agents
url http://www.sciencedirect.com/science/article/pii/S135041772400419X
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