Patterning droplets with durotaxis

TL;DR

This paper demonstrates that simple liquid droplets can undergo durotaxis, moving along substrate stiffness gradients without external gradients, enabling new large-scale patterning techniques for microfluidic and microfabrication applications.

Contribution

It reveals that liquid droplets can exhibit durotaxis solely through substrate stiffness modulation, a phenomenon previously observed only in cells.

Findings

Droplets move toward stiffer regions on soft substrates.

Durotaxis occurs without chemical, thermal, electrical, or topographical gradients.

This method allows precise droplet positioning for patterning applications.

Abstract

Numerous cell-types have shown a remarkable ability to detect and move along gradients in stiffness of an underlying substrate -- a process known as durotaxis. The mechanisms underlying durotaxis are still unresolved, but generally believed to involve active sensing and locomotion. Here, we show that simple liquid droplets also undergo durotaxis. By modulating substrate stiffness, we obtain fine control of droplet position on soft, flat substrates. Unlike other control mechanisms, droplet durotaxis works without imposing chemical, thermal, electrical or topographical gradients. This enables a new approach to large-scale droplet patterning and is potentially useful for many applications, such as microfluidics, thermal control and microfabrication.