Droplet Migration Characteristics on Liquid-Infused Surfaces by Mechanical Vibration.

In industrial applications such as condensation heat transfer, frost suppression, and fog collection, the droplet in the Wenzel state exhibits a strong adhesion to the surface, hindering its migration. To prevent the wetting transition and improve droplet migration, a novel method by combining wettability gradients, liquid infusion, and mechanical vibration is proposed in this paper. A curved microgrooved surface with gradient wettability is fabricated via photolithography on a silicon wafer, and then, silicone oil is infused to form the liquid-infused surface. Subsequently, a vertical vibration is applied to induce droplet deformation, enhancing directional migration. To characterize droplet deformation, the maximum deformation coefficient (βm) is introduced, and it consistently varies with the average migration velocity (vavg). The effects of vibration parameters, surface area fraction, droplet volume, and surface tension on vavg and βm are analyzed. Results indicate that the vibration deformation of droplets changes with vibration frequency. At the resonance frequency, the droplet exhibits significant stretching and spreading, resulting in a marked increase in vavg. Furthermore, there exists an optimal amplitude at the resonance frequency. Additionally, reducing the solid area fraction significantly weakens contact line pinning, further increasing the vavg and βm. As the droplet volume and surface tension increase, both vavg and βm increase. Experimental results and theoretical analysis reveal a linear correlation between βm and CaOh-1. This work provides theoretical and technical insights into controlling droplet migration, offering a new perspective for optimization in industrial applications.