Controlled liquid/solid mobility using external fields on lubricant-impregnated surfaces

Abstract

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.

What is claimed is: 
     
         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.