Droplets Crawling on Peristome‐Mimetic Surfaces

Abstract

Controlling the mobility of liquids along surfaces is widely exploited in various technologies to achieve self‐lubrication, phase‐change heat transfer, and microfluidics. Despite commendable progress in directional liquid transport on peristome‐mimetic surfaces, liquid merely spreads directionally with a wetted trail remaining. It is a challenge to achieve directional contracting of spreading liquid at the rear side and ultimately unidirectional motion in bulk from one site to another. Here it is shown that liquids resting on the peristome‐mimetic surfaces can crawl directionally and rapidly in an inchworms‐like way under the action of sudden spontaneous bubbles levitation. Vacuuming or chemical reaction induces sudden nucleation, growth, coalescence (Ostwald ripening process), and rupture of bubbles in the asymmetric microcavities of the peristome‐mimetic surface with directional overpressure beneath the liquid, resulting in the guided contracting and spreading of the liquid. Bubbles regulate this new mode of liquid directional motion. The strategy offers opportunities for liquids directional motion for various applications, such as in microfluidic devices, oil–water separation, and water collection systems.

Replica of Bionic Nepenthes Peristome-like and Anti-Fouling Structures for Self-Driving Water and Raman-Enhancing Detection

“…The zwitterion polymer (2-methacryloyloxyethyl phosphorylch cation flowchart is shown in Figure 3. The bionic replica of the PDMS treated by plasma cleaning for 1 min (Figure 3a) and then immerse (Figure 3b) [27,28]. In addition to activating the surface functional gro treatment can effectively improve the uniformity of the modification pre-treated PDMS was treated by oxygen atmospheric plasma (AP P Electronic Co., Ltd., Taipei, Taiwan) (Figure 3c) to polymerize the MPC polymer brushes (Figure 3d) at an operating power of 1.2 kW and ox slm (L/min) for 10 s, and a 1.2 cm distance was maintained from the p…”

“…The zwitterion polymer (2-methacryloyloxyethyl phosphorylcholine, MPC) modification flowchart is shown in Figure 3. The bionic replica of the PDMS membrane was pre-treated by plasma cleaning for 1 min (Figure 3a) and then immersed in MPC solution (Figure 3b) [27,28]. In addition to activating the surface functional groups, the hydrophilic treatment can effectively improve the uniformity of the modification.…”

“…The plane structure is reproduced on PDMS through transfer-printing technology [13,26,27]. Most studies choose PDMS as the transfer material due to its excellent pattern reproduction accuracy, easy preparation, and ease of observation, etc.…”

Anisotropy-induced directional self-transportation of low surface tension liquids: a review

“…59,61 Experimental and numerical studies have characterized the directional transportation of these unique structures in terms of surface wettability, as well as the viscosity and surface tension of the liquid. [66][67][68][69][70] In 2017, Chen et al 6 also fabricated bio-inspired unidirectional liquid spreading surfaces using inclined UV exposure of SU-8 photoresist. Various arc-curvatures and wedge angles were fabricated to investigate the effect of structural features on the spread mechanism (Fig.…”

Bioinspired Surface with Superwettability for Controllable Liquid Dynamics

“…Revealing the mechanisms behind these natural occurrences not only helps to solve the annoying problems of liquid overflow and splashing events that occur in daily life [ 12–14 ] but also inspires the innovative applications, such as agricultural irrigation, pesticide sprays, fog collection, lubrication, printing, microfluidic operation, soft robotics, oil–water separation, seawater desalination, biomedicine, microreactor, self‐assembly, and energy conversion. [ 2,15–31 ]…”