Numerical analysis of viscoelasticity of two-dimensional fluid membranes under oscillatory loadings

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Main Authors: Takeishi, Naoki, Santo, Masaya, Yokoyama, Naoto, Wada, Shigeo
Format: Preprint
Published: 2022
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author Takeishi, Naoki
Santo, Masaya
Yokoyama, Naoto
Wada, Shigeo
author_facet Takeishi, Naoki
Santo, Masaya
Yokoyama, Naoto
Wada, Shigeo
contents Biomembranes consisting of two opposing phospholipid monolayers, which comprise the so-called lipid bilayer, are largely responsible for the dual solid-fluid behavior of individual cells and viruses. Quantifying the mechanical characteristics of biomembrane, including the dynamics of their in-plane fluidity, can provide insight not only into active or passive cell behaviors but also into vesicle design for drug delivery systems. Despite numerous studies on the mechanics of biomembranes, their dynamical viscoelastic properties have not yet been fully described. We thus quantify their viscoelasticity based on a two-dimensional (2D) fluid membrane model, and investigate this viscoelasticity under small amplitude oscillatory loadings in micron-scale membrane area. We use hydrodynamic equations of bilayer membranes, obtained by Onsager's variational principle, wherein the fluid membrane is assumed to be an almost planar bilayer membrane. Simulations are performed for a wide range of oscillatory frequencies $f$ and membrane tensions. Our numerical results show that as frequencies increase, membrane characteristics shift from an elastic-dominant to viscous-dominant state. Furthermore, such state transitions obtained with a 1-$μ$m-wide loading profile appear with frequencies between $O(f) = 10^1-10^2$ Hz, and almost independently of surface tensions. We discuss the formation mechanism of the viscous- or elastic-dominant transition based on relaxation rates that correspond to the eigenvalues of the dynamical matrix in the governing equations.
format Preprint
id arxiv_https___arxiv_org_abs_2210_11074
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Numerical analysis of viscoelasticity of two-dimensional fluid membranes under oscillatory loadings
Takeishi, Naoki
Santo, Masaya
Yokoyama, Naoto
Wada, Shigeo
Biological Physics
Soft Condensed Matter
Biomembranes consisting of two opposing phospholipid monolayers, which comprise the so-called lipid bilayer, are largely responsible for the dual solid-fluid behavior of individual cells and viruses. Quantifying the mechanical characteristics of biomembrane, including the dynamics of their in-plane fluidity, can provide insight not only into active or passive cell behaviors but also into vesicle design for drug delivery systems. Despite numerous studies on the mechanics of biomembranes, their dynamical viscoelastic properties have not yet been fully described. We thus quantify their viscoelasticity based on a two-dimensional (2D) fluid membrane model, and investigate this viscoelasticity under small amplitude oscillatory loadings in micron-scale membrane area. We use hydrodynamic equations of bilayer membranes, obtained by Onsager's variational principle, wherein the fluid membrane is assumed to be an almost planar bilayer membrane. Simulations are performed for a wide range of oscillatory frequencies $f$ and membrane tensions. Our numerical results show that as frequencies increase, membrane characteristics shift from an elastic-dominant to viscous-dominant state. Furthermore, such state transitions obtained with a 1-$μ$m-wide loading profile appear with frequencies between $O(f) = 10^1-10^2$ Hz, and almost independently of surface tensions. We discuss the formation mechanism of the viscous- or elastic-dominant transition based on relaxation rates that correspond to the eigenvalues of the dynamical matrix in the governing equations.
title Numerical analysis of viscoelasticity of two-dimensional fluid membranes under oscillatory loadings
topic Biological Physics
Soft Condensed Matter
url https://arxiv.org/abs/2210.11074