Shape-shifting droplet networks

TL;DR

This paper demonstrates how programmable droplet networks can change shape through osmotic gradients, enabling reversible folding and unfolding, with potential applications in osmotic robotics.

Contribution

It introduces a method to induce reversible shape transformations in droplet networks via osmotic interactions, advancing the development of osmotic robotic systems.

Findings

Reversible folding-unfolding observed through molecular dynamics simulations.

Networks become faceted via buckling as they change shape.

Quasi-one-dimensional networks evolve into three-dimensional structures.

Abstract

We consider a three-dimensional network of aqueous droplets joined by single lipid bilayers to form a cohesive, tissue-like material. The droplets in these networks can be programmed to have distinct osmolarities so that osmotic gradients generate internal stresses via local fluid flows to cause the network to change shape. We discover, using molecular dynamics simulations, a reversible folding-unfolding process by adding an osmotic interaction with the surrounding environment which necessarily evolves dynamically as the shape of the network changes. This discovery is the next important step towards osmotic robotics in this system. We also explore analytically and numerically how the networks become faceted via buckling and how quasi-one-dimensional networks become three-dimensional.