Elastic deformation during dynamic force measurements in viscous fluids

TL;DR

This paper reviews the elastohydrodynamic interactions between viscous fluids and deformable surfaces, highlighting their impact on force measurements and discussing current challenges in understanding soft hydrodynamic phenomena.

Contribution

It provides a comprehensive theoretical and experimental overview of elastic deformation effects in viscous fluid interactions during dynamic force measurements.

Findings

Elastic deformation influences surface force measurements.

Hydrodynamic interactions are affected by substrate properties.

Current challenges include substrate layering and viscoelastic effects.

Abstract

Understanding and harnessing the coupling between lubrication pressure and elasticity provides materials design strategies for applications such as adhesives, coatings, microsensors, and biomaterials. Elastic deformation of compliant solids caused by viscous forces can also occur during dynamic force measurements in instruments such as the surface forces apparatus (SFA) or the atomic force microscope (AFM). We briefly review hydrodynamic interactions in the presence of soft, deformable interfaces in the lubrication limit. More specifically, we consider the scenario of two surfaces approaching each other in a viscous fluid where one or both surfaces is deformable, which is also relevant to many force measurement systems. In this article the basic theoretical background of the elastohydrodynamic problem is detailed, followed by a discussion of experimental validation and considerations, especially for the role of elastic deformation on surface forces measurements. Finally, current challenges to our understanding of soft hydrodynamic interactions, such as the consideration of substrate layering, poroelasticity, viscoelasticity, surface heterogeneity, as well as their implications are discussed.