Coalescence-induced jumping of droplets on superomniphobic surfaces with macrotexture

Vahabi, Hamed; Wang, Wei; Mabry, Joseph M.; Kota, Arun K.

doi:10.1126/sciadv.aau3488

Cited by 123 publications

(113 citation statements)

References 42 publications

Supporting

Mentioning

111

Contrasting

Order By: Relevance

“…In section 2.2, we have defined the surface energy and the kinetic energy. Based on these discussions, we denoted the initial surface energy as Esurf,i , Esurf,i = Ai, the surface energy when the droplet departs from the surface 38 where Ai is the initial surface area of two droplets and Ad is the surface area when the droplet departs from the surface. The energy conversion rate can be obtained according to the following formula.…”

Section: Energy Analysismentioning

confidence: 99%

“…Designing special structures to enhance jumping is also a hot topic in this field. Both Wang et al 37 and Vahabi et al 38 set ridges between two droplets on a smooth superhydrophobic surface, and concluded that the droplet jumping height as well as the energy conversion rate increased significantly comparing with jumping on a superhydrophobic surface without a ridge.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Droplet jumping induced by coalescence of a moving droplet and a static one: Effect of initial velocity

Chu

Zhang

et al. 2020

Chemical Engineering Science

View full text Add to dashboard Cite

The phenomenon of coalescence-induced droplet jumping on superhydrophobic surfaces has a wide range of applications such as hotspot cooling, surface self-cleaning, anti-icing, and defrosting. Previous experimental and numerical studies mainly focused on the coalescence of static droplets with varying droplet properties and substrate structures. However, in practice, it is more common to see a moving droplet hit a stationary one, which leads to a coalesced droplet jumping from the surface. To explore the effect of initial velocity on the jumping behavior of coalesced droplet, we performed simulations using the volume of fluid method with a dynamic contact angle model, and validated the simulation results against our experiments. We analyzed the morphology evolutions, velocity variations and energy conversion rates during the jumping process. The results show that the initial velocity of the moving droplet accelerates the droplet deformation during jumping, resulting in a unique departure feature. Droplet departs at different stages under different initial velocities, and the departure velocity is approximately constant at the first stage and then increases with increasing initial velocity. The variation in energy conversion rate is consistent with the departure velocity which suggests the conversion rate has a slight change in low initial velocity range. This work shall bring new insights into the droplet jumping regulation and promote the application of droplet jumping in related fields.

show abstract

Section: Energy Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Droplet jumping induced by coalescence of a moving droplet and a static one: Effect of initial velocity

Chu

Zhang

et al. 2020

Chemical Engineering Science

View full text Add to dashboard Cite

show abstract

“…To our surprise, the model captures space-time symmetry-breaking motions observed in real drops and may anticipate nonlinear behavior like torus dynamics and droplet jumping, currently under active study for real drops [19].…”

Section: Resultsmentioning

confidence: 93%

Steiner triangular drop dynamics

Wesson

Steen

2020

Chaos: An Interdisciplinary Journal of Nonlinear Science

View full text Add to dashboard Cite

Steiner's circumellipse is the unique regularization of any triangle to a circumscribed ellipse with the same centroid, a regularization that motivates our introduction of the Steiner triangle as a minimal model of a liquid droplet. The center of mass of the Steiner drop, a deforming triangle with one side making sliding contact against a planar basal support, is governed by Newton's law. The dynamical system of the Steiner drop lives in a four dimensional phase space and exhibits a rich one-parameter family of dynamics. Two invariant manifolds are identified with "bouncing" and "rocking" periodic motions; these intersect at the stable equilibrium and are surrounded by nested quasiperiodic motions. We study the inherently interesting dynamics and also find that this model, however minimal, can capture space-time symmetries of real drops.

show abstract

“…Superomniphobic surfaces are extremely repellent to and display negligible adhesion with virtually all contacting liquids, having high or low surface tension . Such high liquid repellency and negligible adhesion, which lead to high droplet mobility on the surface, have attracted tremendous interests in wide variety of applications such as self‐cleaning, chemical shielding, corrosion resistance, water energy harvesting, membrane separation, and lab‐on‐chip devices . As such, superomniphobic surfaces have been fabricated on numerous substrates such as metals, polymers, glass, and paper .…”

mentioning

confidence: 99%

Superomniphobic Papers for On‐Paper pH Sensors

Movafaghi

Cackovic

Wang

et al. 2019

Adv Materials Inter

Self Cite

View full text Add to dashboard Cite

surface, have attracted tremendous interests in wide variety of applications such as self-cleaning, [2,3] chemical shielding, [4] corrosion resistance, [5] water energy harvesting, [6][7][8][9] membrane separation, [10] and lab-on-chip devices. [11,12] As such, superomniphobic surfaces have been fabricated on numerous substrates such as metals, polymers, glass, and paper. [13][14][15][16][17][18][19][20][21][22][23][24] Among these, paper-based superomniphobic surfaces are of great importance because paper is flexible, inexpensive, lightweight, breathable, and recyclable. However, prior reports [25][26][27][28][29][30][31] that relied on tuning the inherent heterogenous texture of papers to achieve superomniphobicity have failed to demonstrate low roll-off angle (or low contact angle hysteresis, indicative of negligible solidliquid adhesion) with low surface tension liquids. [32] To overcome this issue, in this work, we developed a superomniphobic paper through a simple technique of growing nanofilaments on the microfibers of the paper. Unlike prior work, [16,21,[33][34][35] our superomniphobic paper displays very low roll-off angle, indicative of ultra-high droplet mobility, even with low surface tension liquids (e.g., n-hexadecane). Further, the required hierarchical texture is formed using a grow-from approach on inherent microfibers of the paper, without noticeably altering the microscale features (i.e., diameter and distance of the microfibers). We also developed a facile method to control the motion and adhesion of the droplets on the superomniphobic paper. Utilizing the liquid mobility in a controlled manner on our superomniphobic papers, we fabricated a simple on-paper pH sensor. We envision that due to simple fabrication technique, flexibility, lightweight, breathability, selective permeability, and ultra-high droplet mobility, our superomniphobic papers will have numerous applications including lab-on-paper devices, water-oil separation, and devices (e.g., water drones and microrobots) with enhanced weight-bearing capacity.When a liquid droplet contacts a nontextured (i.e., smooth) solid surface, it displays an equilibrium (or Young's) contact angle θ Y at triple-phase contact line. [36] Whereas, if the droplet contacts a textured solid surface, it displays an apparent contact angle θ * and adopts either the Wenzel (or fully wetted) state [37] or the Cassie-Baxter state [38] to minimize its overall free energy. In the Cassie-Baxter state, which is preferred for designing super-repellent surfaces, an air layer is trapped between the surface texture and the contacting liquid droplet.

show abstract

Coalescence-induced jumping of droplets on superomniphobic surfaces with macrotexture

Abstract: Superomniphobic surfaces with macrotextures allow coalescence-induced jumping of droplets at Ohnesorge number >1.

Cited by 123 publications

References 42 publications

Droplet jumping induced by coalescence of a moving droplet and a static one: Effect of initial velocity

Droplet jumping induced by coalescence of a moving droplet and a static one: Effect of initial velocity

Steiner triangular drop dynamics

Superomniphobic Papers for On‐Paper pH Sensors

Contact Info

Product

Resources

About