Lateral hydrodynamics in supported membranes: The Evans-Sackmann model and its extensions

TL;DR

This paper reviews the Evans-Sackmann hydrodynamic model for lateral transport in supported membranes, covering its development, extensions, and applications including active and chiral membranes with odd viscosity.

Contribution

It provides a comprehensive overview of the model's extensions and recent advances in understanding membrane hydrodynamics, including active and chiral effects.

Findings

Quantitative interpretation of tracer diffusion in supported bilayers.

Extensions to include inclusions, phase separation, and many-body interactions.

Discussion of odd viscosity as a signature of membrane chirality.

Abstract

We review the theoretical development and modern applications of the Evans-Sackmann hydrodynamic model for lateral transport in supported fluid membranes. We first cover the original formulation, emphasizing the linear momentum decay term that captures membrane-substrate coupling mediated by a thin lubricating fluid layer. This coupling term enables quantitative interpretation of tracer diffusion measurements in supported bilayers. Building on this foundation, we survey theoretical extensions that relax standard boundary conditions at the inclusion perimeter, where inclusions refer to embedded objects such as proteins, lipid domains, or tracer particles within the membrane. We discuss the drag of a disk and a liquid domain, as well as the dynamics of membrane phase separation. We further highlight how the supported-membrane mobility tensor serves as a unifying tool for systematic treatments of correlated diffusion, polymer dynamics, phase separation kinetics, and many-body interactions in quasi-two-dimensional environments. Finally, we discuss recent extensions to active and chiral membranes, where odd viscosity provides a transverse hydrodynamic response and offers a possible route for detecting chirality in two-dimensional fluids.