Sustained and Uniform Self-transport of Condensate Droplets via a Bionic Dual-Gradient Wedged Groove

Droplet self-transport offers considerable potential for applications such as thermal management, water harvesting, and lab-on-a-chip systems. However, its unsteady dynamics greatly impede the stable and long-distance transport essential for condensate removals and condensation enhancement. Herein, we propose a bionic dual-gradient wedged groove to regulate the nucleation site and enable the continuous and uniform transport of condensate droplets. Molecular dynamics simulations and theoretical analysis show that the droplets form and move along an energetically favorable pathway and are persistently constricted by groove walls while growing. The resultant Laplace pressure gradient provides a sustained driving force for continuous droplet motion. Moreover, it is revealed that the droplet transport performance is influenced by the groove geometry and wettability synergistically. Increasing the groove depth and surface hydrophobicity and appropriately reducing the groove opening angle can modulate the balance between actuation and resistance forces, thereby improving the droplet transport efficiency. These findings are expected to advance the understanding of sustained and uniform droplet transport and offer insights into achieving efficient condensate removal in advanced heat transfer technologies.