Wettability-Engineered Meshes for Gas Microvolume Precision Handling in Liquids

Abstract

The interaction of rising gas bubbles with submerged air-repelling or air-attracting surfaces is relevant to various technological applications that rely on gas-microvolume handling or removal. This work demonstrates how submerged metal meshes with super air-attracting/repelling properties can be employed to manipulate microvolumes of air, rising buoyantly in the form of bubbles in water. Superaerophobic meshes are observed to selectively allow the passage of air bubbles depending on the mesh pore size, the bubble volume-equivalent diameter, and the bubble impact velocity on the mesh. On the other hand, superaerophilic meshes reduce or amplify the volume captured from a train of incoming bubbles. Finally, a spatial wettability pattern on the mesh is used to control the size of the outgoing bubble, and an empirical relation is formulated to predict the released gas volume. The study demonstrates how porous materials with controlled wettability can be used to precisely modulate and control the outcome of bubble/mesh interactions.

Machine Learning Prediction of TiO2-Coating Wettability Tuned via UV Exposure

“…Over time, developments in surface engineering techniques have facilitated the manipulation of different liquids on wettable and nonwettable surfaces. In particular, different spreading behavior of liquids on wettable and nonwettable surfaces has demonstrated a variety of interesting phenomena by confining and transporting liquid volumes passively via spatially juxtaposed wettable and nonwettable regions, partitioned by sharp wettability contrast lines. − In the past two decades, applications of such surfaces have become increasingly popular in different areas, such as electronic cooling, − condensation heat transfer, , open-surface microfluidics, and air bubble manipulation underwater. , …”

Influence of Surface Wettability on Bubble Formation and Motion

“…Surface wettability is generally characterized by the equilibrium contact angle (CA) of a sessile droplet on the surface in air. The superhydrophilic (SHI) surface in air (CA < 10°) becomes superaerophobic under water and vice versa for the superhydrophobic (SHO) surface (CA > 150°). , Air bubble manipulation in a submerged state has been investigated both using active − and passive methods − related to surface wetting properties. For example, bubble movement on the superwetted surface covered by special lubricant (ferrofluid or paraffin) under the stimulus of the magnetic field or light is investigated for the bubble intentional control. , In addition, some surfaces doped with magnetic particles are used to manipulate bubble motion under the stimulus of the magnetic field .…”

“…For example, bubble movement on the superwetted surface covered by special lubricant (ferrofluid or paraffin) under the stimulus of the magnetic field or light is investigated for the bubble intentional control. , In addition, some surfaces doped with magnetic particles are used to manipulate bubble motion under the stimulus of the magnetic field . Most of passive methods are based on surface wettability patterns such as wedge-shaped channel, − constant-width channel, Janus surface, − cone, , wettability gradient surfaces, , and dual rails . The surfaces were mainly fabricated by chemical etching ,, and laser milling. ,− ,,, The pumpless air bubble spreading is driven by the force arising from the asymmetric channel geometry or wettability gradient.…”

“…Most of passive methods are based on surface wettability patterns such as wedge-shaped channel, − constant-width channel, Janus surface, − cone, , wettability gradient surfaces, , and dual rails . The surfaces were mainly fabricated by chemical etching ,, and laser milling. ,− ,,, The pumpless air bubble spreading is driven by the force arising from the asymmetric channel geometry or wettability gradient.…”

Lateral Spreading of Gas Bubbles on Submerged Wettability-Confined Tracks

“…The advancement of surface engineering techniques has facilitated scalable approaches for fabricating wettable and nonwettable surfaces, on which a variety of liquids can be manipulated. Distinctly different behaviors of fluids encountering wettable and nonwettable surfaces enable effective confinement of liquid volumes on surfaces possessing spatially juxtaposed wettable and nonwettable domains separated by a sharp wettability-contrast line. − The scientific literature from the last two decades bears testimony to the applicability of wettability-patterned surfaces in open-surface microfluidics, pool boiling, condensation, , and electronics cooling. , A superhydrophobic (water-repelling) surface behaves as a superaerophilic (air-attracting) one when submerged in water, and vice versa for a superhydrophilic surface. , A review of the various fabrication techniques for obtaining superaerophobic and superaerophilic surfaces was recently presented by George et al Numerous studies have shown possible applications of such surfaces in gas harvesting, − wastewater remediation, catalytic action, drag reduction, etc.…”