Fibrotaxis: gradient-free, spontaneous and controllable droplet motion on soft solids

Area of Science:

• Fluid dynamics
• Materials science
• Surface science

Background:

• Passive droplet transport commonly relies on material property gradients, limiting velocity and distance.
• Existing methods face challenges due to intrinsic length scales and gradient dependence.

Purpose of the Study:

• To introduce and investigate droplet fibrotaxis, a novel gradient-free droplet transport mechanism.
• To explore the key parameters influencing droplet velocity and transport distance in fibrotaxis.

Main Methods:

• High-fidelity numerical simulations were employed to model the droplet-solid interaction.
• Systematic variation of parameters including fluid wettability, fiber orientation, anisotropy strength, and elastocapillary number.

Main Results:

• Fibrotaxis achieves spontaneous and gradient-free droplet transport.
• Controllable droplet velocity and long-range transport were demonstrated.
• Fluid wettability, fiber orientation, anisotropy strength, and elastocapillary number were identified as critical parameters.

Conclusions:

• Fibrotaxis offers a promising alternative to gradient-based droplet transport methods.
• This mechanism has significant potential for applications in self-cleaning surfaces, water harvesting, and medical diagnostics.