CONTROLLED LIQUID/SOLID MOBILITY USING EXTERNAL FIELDS ON LUBRICANT-IMPREGNATED SURFACES
A method for precise control of movement of a motive phase on a lubricant-impregnated surface includes providing a lubricant-impregnated surface, introducing the motive phase onto the lubricant-impregnated surface, and exposing the droplets to an electric and/or magnetic field to induce controlled movement of the droplets on the surface. The lubricant-impregnated surface includes a matrix of solid features spaced sufficiently close to stably contain the impregnating lubricant therebetween or therewithin. The motive phase is immiscible or scarcely miscible with the impregnating lubricant.
1 . A method for controlling movement of a motive phase on a liquid-impregnated surface, the method comprising:
providing a liquid-impregnated surface, said surface comprising an impregnating liquid and a matrix of solid features spaced sufficiently close to contain the impregnating liquid therebetween or therewithin;
introducing the motive phase onto the surface, the motive phase comprising (or consisting essentially of) a phase that is immiscible with (or only scarcely miscible with) the impregnating liquid; and
exposing the motive phase to an electric field and/or a magnetic field to induce controlled movement of the motive phase on the surface.
2 . The method of claim 1 , further comprising applying a non-uniform electric field to induce the controlled movement of the motive phase on the surface.
3 . The method of claim 1 , further comprising applying an non-uniform magnetic field to induce the controlled movement of the motive phase on the surface and wherein the liquid droplets are cloaked by the impregnating liquid.
4 . The method of claim 1 , wherein the impregnating liquid comprises a member selected from the group consisting of silicone oil, a perfluorocarbon liquid, a perfluoro fluorinated vacuum oil, a fluorinated coolant, an ionic liquid, a fluorinated ionic liquid that is immiscible with water, a silicone oil comprising PDMS, a fluorinated silicone oil, a liquid metal, an electro-rheological fluid, a magneto-rheological fluid, a ferrofluid, a dielectric liquid, a hydrocarbon liquid, a fluorocarbon liquid, a refrigerant, a vacuum oil, a phase-change material, a semi-liquid, grease, synovial fluid, bodily fluid, or any combination thereof.
5 . The method of claim 1 , wherein the motive phase is liquid droplets.
6 . The method of claim 5 , wherein the liquid-impregnated surface is a surface of a condenser, wherein the liquid droplets comprise a condensing liquid, and wherein the controlled movement of the liquid droplets on the surface enhances shedding of the condensing liquid, thereby enhancing efficiency of heat transfer provided by the condenser.
7 . The method of claim 1 , wherein the liquid-impregnated surface is a surface of a solar panel, wherein the motive phase comprises dust particles, and wherein the controlled movement of the motive phase on the surface effectively removes the dust particles from the solar panel.
8 . The method of claim 7 , wherein the solar panel self-generates (e.g., by collecting energy from the sun) sufficient energy to provide the electric field to induce controlled movement of the motive phase on the surface.
9 . The method claim 1 , wherein the motive phase comprises biological material.
10 . The method of claim 1 , wherein the motive phase is ice and wherein exposing the ice to the electric and/or the magnetic field induces controlled movement of the ice on the surface to de-ice the surface.
11 . The method of claim 1 , wherein the surface is a surface of a vessel and wherein the motive phase is oil or gas in contact with the surface.
12 . The method of claim 11 , wherein exposing the oil or gas to the electric and/or the magnetic field induces the oil or gas to move in a controlled manner and/or to prevent buildup of the oil or gas on the surface of the vessel.
13 . The method of claim 1 , wherein exposing the motive phase to the electric and/or the magnetic field induces inhibition of hydrate adhesion upon the surface.
14 . The method of claim 1 , wherein exposing the motive phase to the electric and/or the magnetic field comprises reducing an amount of scale buildup formed on the surface.
15 . The method of claim 1 , wherein exposing the motive phase to the electric and/or the magnetic field induces the motive phase to move to a desired location.
16 . The method of claim 1 , wherein the liquid-impregnated surface is a microchannel of an electro hydrodynamic (EHD) pump.
17 . The method of claim 1 , wherein φ=0, where φ is a representative fraction of the projected surface area of the liquid-impregnated surface corresponding to non-submerged solid at equilibrium.
18 . The method of claim 1 , wherein one or both of the following holds:
(i) 0<φ≦0.25, where φ is a representative fraction of the projected surface area of the liquid-impregnated surface corresponding to non-submerged solid at equilibrium; and
(ii) S ow(a) <0, where S ow(a) is spreading coefficient, defined as γ wa −γ wo −γ oa , where γ is the interfacial tension between the two phases designated by subscripts w, a, and o, where w is the liquid of the liquid droplets (e.g., water), a is surrounding gas (e.g., air), and o is the impregnating liquid (e.g., oil).
19 . The method of claim 1 , wherein the lubricant entirely cloaks the motive phase.
20 . The method of claim 1 , wherein the lubricant does not cloak the motive phase.
21 . The method of claim 1 , wherein the lubricant forms pulled-up regions around the motive phase to induce movement of the motive phase.
22 . The method of claim 1 , further comprising replenishing a supply of the impregnating liquid.
23 . The method of claim 1 , wherein the surface is microtextured.
24 . The method of claim 1 , wherein the solid features comprise at least one member selected from the group consisting of a polymeric solid, a ceramic solid, a fluorinated solid, an intermetallic solid, and a composite solid.
25 . The method of claim 1 , wherein the solid features comprise a chemically modified surface, a coated surface, and/or a surface with a bonded monolayer.
26 . The method of claim 1 , wherein the solid features comprise at least one member selected from the group consisting of posts, nanoneedles, nanograss, substantially spherical particles, and amorphous particles.
27 . An article comprising a liquid-impregnated surface, said surface comprising an impregnating liquid and a matrix of solid features spaced sufficiently close to stably contain the impregnating liquid therebetween or therewithin, wherein the impregnating liquid comprises a ferrofluid, the ferrofluid being configured to induce controlled movement of a motive phase introduced on the surface when the motive phase is exposed to a magnetic field.
28 . An article comprising a liquid-impregnated surface, said surface comprising an impregnating liquid and a matrix of solid features spaced sufficiently close to stably contain the impregnating liquid therebetween or therewithin, wherein the impregnating liquid is configured to induce controlled movement of a motive phase introduced on the surface when the motive phase is exposed to an electric field and/or a magnetic field.
29 . The article of claim 27 , wherein the article is a member selected from the group consisting of a pipeline, a steam turbine part, a gas turbine part, an aircraft part, a wind turbine part, eyeglasses, a mirror, a power transmission line, a container, a windshield, an engine part, a nozzle, a tube, or a portion or coating thereof.