Elastic Cheerios effect: self-assembly of cylinders on a soft solid

TL;DR

This paper investigates how rigid cylinders on soft gels interact and self-assemble through elastic deformations, revealing exponential attraction forces and clustering behavior driven by the gel's energy landscape.

Contribution

It introduces an elastic analog of the Cheerios effect, combining experiments, scaling, and simulations to characterize cylinder interactions on soft solids.

Findings

Effective two-body interaction is exponential in separation distance.

Cylinders cluster when close, but become elastically arrested if too far apart.

The dynamics follow an exponential behavior with respect to separation.

Abstract

A rigid cylinder placed on a soft gel deforms its surface. When multiple cylinders are placed on the surface, they interact with each other via the topography of the deformed gel which serves as an energy landscape; as they move, the landscape changes which in turn changes their interaction. We use a combination of experiments, simple scaling estimates and numerical simulations to study the self-assembly of cylinders in this elastic analog of the Cheerios effect for capillary interactions on a fluid interface. Our results show that the effective two body interaction can be well described by an exponential attraction potential as a result of which the dynamics also show an exponential behavior with respect to the separation distance. When many cylinders are placed on the gel, the cylinders cluster together if they are not too far apart; otherwise their motion gets elastically arrested.