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Title: A novel model for an encapsulated microbubble based on transient network theory
Encapsulated microbubbles (EMBs) are widely used to enhance contrast in ultrasound sonography and are finding increasing use in biomedical therapies such as drug/gene delivery and tissue ablation. EMBs consist of a gas core surrounded by a stabilizing shell made of various materials, including polymers, lipids and proteins. We propose a novel model for a spherical EMB that utilizes a statistically-based continuum theory based on transient networks to simulate the encapsulating material. The use of transient network theory provides a general framework that allows a variety of viscoelastic shell materials to be modeled, including purely elastic solids or viscous fluids. This approach permits macroscopic continuum quantities – such as stress, elastic energy and entropy – to be calculated locally based on the network configuration at a given location. The model requires a minimum number of parameters that include the concentration of network elements, and the rates of attachment and detachment of the elements to and from the network. Using measured properties for a phospholipid bilayer, the model closely reproduces the experimentally-measured radial response of an ultrasonically-driven, lipid-coated microbubble. The model can be readily extended to large nonspherical EMB deformations, which are important in many biomedical applications.  more » « less
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24th European Symposium on Ultrasound Contrast Imaging
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National Science Foundation
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