Viscous-capillary entrainment on bioinspired millimetric structure for sustained liquid transfer

Abstract

Liquid entrainment with a solid architecture passing through the fluid-fluid interface is ubiquitous and widely used in industrial processes as a liquid transfer method. Besides liquid properties, solid structures play a core role in entrainment. Although the influence of its macroscopic curvatures and microscale roughness has attracted years of research, the effect and potential of the commonly seen millimetric structures have not been sufficiently explored and exploited. Here, we demonstrate enhanced liquid entrainment on the millimetric structured surface by the co-effect of viscosity and capillarity for sustained liquid transfer of small deviation, including high-quantity uptake and practically operational drainage with small and relatively uniform droplet dripping time of varied liquid viscosities. With the overall process of viscous-capillary entrainment, we achieve stable cyclical arrayed liquid transport, showing its potential for sustained liquid transfer in intractable situations in laboratory, industry, and even daily life.

Bio-inspired sustained entrainment in immiscible liquid–liquid systems for collecting floating oil

“…1(a)). 12,15,22,[42][43][44] Considering the tongue's enhancement effect on the air-liquid entrainment, we abstracted it as a typical model to investigate its behavior in the liquid-liquid entraining process. The experimental setup includes a 3D-printed rod as the solid object, a liquid tank containing two liquids, and a high-speed camera to record the entrainment (Fig.…”

“…In summary, our study identified two primary mechanisms to hinder the upward drainage of entrained oil in our experimental setup: (1) use of spiky plates: by employing spiky plates with a high number density, we were able to pin the liquid–liquid interface effectively. This action formed periodic menisci with negative Laplace pressure, 22 thereby supporting and stabilizing the oil film above it; (2) oil film ‘necking’: another observed phenomenon was the ‘necking’ of the oil film, which constricted the passage of oil, retaining it below the necking point, as depicted in Fig. 2(d).…”

“…[16][17][18][19][20][21] Examples include the unique surface of a bee's tongue, with its intricate design, which can inspire the development of advanced materials and surfaces for improved liquid handling and retention. 22 Despite these insights, most research on the liquid entrainment problem has primarily concentrated on the interactions between air and liquid phases, [23][24][25][26][27][28] and spawned abundant variants, such as the drop entrainment problem. [29][30][31][32][33][34] The complexities involved in the solid-forced entrainment in liquidliquid systems are oen neglected.…”

“…16–21 Examples include the unique surface of a bee's tongue, with its intricate design, which can inspire the development of advanced materials and surfaces for improved liquid handling and retention. 22…”

Fast prototype and rapid construction of three-dimensional and multi-scaled pitcher for controlled drainage by systematic biomimicry

“…Next, we utilized x-ray imaging coupled with a drop-impact set-up to visualize the water film rupture and drainage on the pitcher's mouth (figure 1(d)). The real-time observations and an in-depth understanding of the mechanism can be achieved by in situ x-ray computer microtomography [46][47][48]. Our experiments involve releasing a water drop (radius R = 2.5 mm, velocity U = 1.0 m•s −1 ) onto a pitcher's mouth and filming the film rupture and drainage dynamics inside the sample chamber of Micro-CT under 25 kV x-ray tube voltage (figure 1(d)).…”