Elastic deformations driven by non-uniform lubrication flows

TL;DR

This paper explores how non-uniform lubrication flows can induce complex, controllable deformations in elastic plates, with potential applications in soft robotics and microfluidic device reconfiguration.

Contribution

It introduces a theoretical framework linking fluid property gradients to elastic deformations, including a method to design zeta-potential distributions for desired shape changes.

Findings

Derived a governing equation relating deformations to fluid property gradients.

Provided a method to determine zeta-potential for specific deformation patterns.

Presented solutions for transient and time-periodic deformation scenarios.

Abstract

The ability to create dynamic deformations of micron-sized structures is relevant to a wide variety of applications such as adaptable optics, soft robotics, and reconfigurable microfluidic devices. In this work we examine non-uniform lubrication flow as a mechanism to create complex deformation fields in an elastic plate. We consider a Kirchoff-Love elasticity model for the plate and Hele-Shaw flow in a narrow gap between the plate and a parallel rigid surface. Based on linearization of the Reynolds equation, we obtain a governing equation which relates elastic deformations to gradients in non-homogenous physical properties of the fluid (e.g. body forces, viscosity, and slip velocity). We then focus on a specific case of non-uniform Helmholtz-Smoluchowski electroosmotic slip velocity, and provide a method for determining the zeta-potential distribution necessary to generate arbitrary static and quasi-static deformations of the elastic plate. Extending the problem to time-dependent solutions, we analyze transient effects on asymptotically static solutions, and finally provide a closed form solution for a Green's function for time periodic actuations.