Self-propelled droplet dynamics on superhydrophobic surfaces under low-pressure conditions
Phys. Rev. E 113, 065506 – Published 22 June, 2026
DOI: https://doi.org/10.1103/zl6s-sqrb
Abstract
The self-removal of sessile droplets under low-pressure conditions is critical for extreme-environment surface engineering. Combining high-speed photography with quantitative analysis, we reveal the unique dynamics of ethylene glycol-water solution droplets on irregular micro-nanostructured superhydrophobic surfaces. The experimental results demonstrate asymmetric depinning driven by evaporation-induced local overpressure gradients, generating a recoil momentum toward the pinned side that propels the droplet to move along the surface at a steady acceleration. This acceleration follows a quadratic scaling law with the evaporation flux. When the local overpressure exceeds the triple-phase line pinning forces, the droplets transition to the levitation phase. However, the unevenness of the surface micro-nanostructures leads to the instability of levitation, causing the droplet to rapidly recontact the surface and enter the secondary steady acceleration phase. Subsequently, the droplet maintains a dual-phase periodic transition mode of acceleration–levitation until it disappears from the field of view. In this study, we elucidate the synergy between recoil momentum and dynamic overpressure, advancing the fundamental understanding of low-pressure complex droplet dynamics and enabling surface morphology design strategies for droplet control in extreme environments.
