US20080164145A1

US20080164145A1 - Devices and Methods for Antifouling

Info

Publication number: US20080164145A1
Application number: US11/940,568
Authority: US
Inventors: Frederick Vosburgh
Original assignee: NEKTON RESEARCH LLC
Current assignee: iRobot Corp
Priority date: 2006-11-20
Filing date: 2007-11-15
Publication date: 2008-07-10

Abstract

A method of clearing a surface of an object contaminated with a polar material includes the steps of: providing an object having a surface with a plurality of spaced apart electrodes, the electrodes being connected with a voltage source and capable of sustaining a time-varying charge; inducing a first electric field on the plurality of electrodes of a magnitude and for a duration to induce drops of the polar material to take a first dimensional aspect; and inducing a second electric field on the plurality of electrodes of a magnitude and for a duration to induce the drops of the polar material to take a second dimensional aspect. With this method, surfaces such as the head window of a periscope can be cleaned/cleared of contaminants without requiring a manual cleaning and without the use of problematic coatings.

Description

RELATED APPLICATION

This application claims priority from U.S. Provisional Patent Application Ser. No. 60/866,520, filed Nov. 20, 2006 and entitled Devices and Methods for Antifouling, the disclosure of which is hereby incorporated herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to systems and methods of antifouling or momentum transfer. More specifically it relates to use of electric fields to transfer momentum to water for the purpose of antifouling or providing force.

BACKGROUND OF THE INVENTION

Underwater vehicles, such as submarines, often have windows and other transparent surfaces through which observations are made. One specific example is a periscope mounted on a submarine that can extend out of the water while the remainder of the submarine remains submerged. Once out of the water, the periscope can be employed to observe nearby objects. In addition, optical sensing via the periscope at visible and IR wavelengths can assist the mission capabilities of a submarine force, e.g. for automated target ID/tracking and intelligence operations.
Unfortunately, submergence of a periscope can lead to growth of biofilm which causes drops to cling to the head window. Exemplary fouling agents that can contribute to biofilm formation include plankton, bacteria, fungi, mud, grime, slime, plaque, kelp, inorganic materials such as salt, and organic materials. If any of these materials adhere to the transparent surface of the periscope, even in droplet form, the visibility of the periscope can be compromised.
Clearing the periscope surface of contaminants can be troublesome. In most cases, either an individual must be sent topside to clean, an activity that typically requires the submarine to surface, or the cleaning must wait until the submarine docks at a port. It would be desirable to provide an alternative clearing technique that can be performed while the submarine is largely submerged.
To avoid visibility problems due to drops, periscope head windows traditionally have been coated with antifouling compounds to prevent biofilm development. Unfortunately, coating life can be shorter than a mission, as well as being highly toxic and problematic to apply (and now many are banned by international treaty). Permitted anti-fouling coatings, such as ablative coatings (see, e.g. U.S. Pat. Nos. 5,545,823 and 7,118,616), coatings that rapidly leach such bacteriostatic materials such as octyl sulfates and zosteric acid to retard microorganism attachment (see, e.g., U.S. Pat. No. 7,087,661), hydrophobic coatings (see, e.g., U.S. Pat. Nos. 6,743,516 and 6,114,446) and interpenetrating networks of glass and silicone (U.S. Pat. No. 6,559,201), provide inadequate anti-fouling activity or are too short-lived to be useful for head window clearing.
In view of the foregoing, a safe, effective and affordable method for anti-fouling of the head window and other surfaces exposed to fouling or other water-borne matter would be desirable.

SUMMARY OF THE INVENTION

As a first aspect, embodiments of the present invention are directed to a method of clearing a surface of an object contaminated with a polar material. The method comprises the steps of: providing an object having a surface with a plurality of spaced apart electrodes, the electrodes being connected with a voltage source and capable of sustaining a time-varying charge; inducing a first electric field on the plurality of electrodes of a magnitude and for a duration to induce drops of the polar material to take a first dimensional aspect; and inducing a second electric field on the plurality of electrodes of a magnitude and for a duration to induce the drops of the polar material to take a second dimensional aspect. With this method, surfaces such as the head window of a periscope can be cleaned/cleared of contaminants without requiring a manual cleaning and without the use of problematic coatings.
As a second aspect, embodiments of the present invention are directed to a method of clearing a surface of an object contaminated with a polar material, comprising the steps of: providing an object having a surface with a plurality of spaced apart electrodes, the electrodes being connected with a voltage source and capable of sustaining a time-varying charge; inducing a first electric field on the plurality of electrodes arranged in alternating first and second sets, wherein the first set takes a positive charge under the first electric field and the second set takes a negative charge under the first electric field, the electric field being induced at a magnitude and for a duration to induce a drop of the polar material to take a first dimensional aspect; and inducing a second electric field on the plurality of electrodes in which at least one electrode in the first set takes a neutral or negative charge and at least one electrode in the second set takes a neutral or positive charge, with the result that the drop of polar liquid moves along the object surface. This method can be performed to cause drops to translate across the surface, thereby removing contaminants.
As a third aspect, embodiments of the present invention are directed to a method of clearing a surface of an object contaminated with a polar material, comprising the steps of: providing an object having a surface with a plurality of spaced apart electrodes, the electrodes being connected with a voltage source and capable of sustaining a time-varying charge; inducing a first electric field on the plurality of electrodes arranged in alternating first and second sets, wherein the first set takes a positive charge under the first electric field and the second set takes a negative charge under the first electric field, the electric field being induced at a magnitude and for a duration to induce a drop of the polar material to take a first flattened shape; ceasing the induction of electric field on the plurality of electrodes, with the result that the drop of polar liquid takes a second relaxed shape; repeating the inducing and ceasing steps to cause the drop of polar liquid to alternately switch between the first and second shapes and provide a scrubbing action to the object surface. This method can clean, clear or defog a surface.
As a fourth aspect, embodiments of the present invention are directed to an object with anti-fouling capability, comprising: a surface with a plurality of spaced apart electrodes, the electrodes being capable of sustaining a time-varying charge; a voltage source connected with the electrodes; and a controller for controlling the voltage of the electrodes, the controller configured to (a) induce a first electric field on the plurality of electrodes of a magnitude and for a duration to induce drops of a polar material on the object surface to take a first dimensional aspect, and (b) induce a second electric field on the plurality of electrodes of a magnitude and for a duration to induce the drops of the polar material to take a second dimensional aspect. One exemplary surface include the head window of the periscope of a submarine, which can be cleaned/cleared of contaminants without the need for manual intervention.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 a is a schematic diagram illustrating the behavior of a water droplet on a surface in accordance with embodiments of the present invention, wherein the water droplet is in a first, relaxed shape under no charge from electrodes in the surface.

FIG. 1 b is a schematic diagram illustrating the water droplet of FIG. 1 a in a second, flattened shape as electrodes in the surface are charged.

FIG. 2 a is a schematic diagram illustrating how the sequential charging of electrodes can move a water droplet over a surface.

FIG. 2 b is a schematic diagram illustrating how repeated charging of electrodes can move a droplet over an entire surface.

FIG. 3 is a perspective view of a windshield for submarine in which electrodes are embedded according to embodiments of the invention.

FIG. 4 is a schematic perspective view of a submarine in which the windshield of FIG. 3 is mounted.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention will now be described more fully hereinafter, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein the expression “and/or” includes any and all combinations of one or more of the associated listed items.
In addition, spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. Thus, the exemplary term “under” can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Well-known functions or constructions may not be described in detail for brevity and/or clarity.
It is well known to those versed in the art that an electric field can interact with a polar molecule such as water and exert a force on the fluid as means of transferring momentum to it. It is also known that momentum transfer can be used to propel a fluid as a means of displacing matter as means of antifouling. As used herein, water is defined as H₂O in liquid or solid form, which material can comprise discrete quantities, such as drops, or a more or less continuous coating, such as bio-slime. Water can also refer to fog, mist, spume, snow or ice, as well as splashing compositions containing water.
Antifouling is defined here as removing undesirable solid or fluid matter from a surface. In some cases antifouling refers more specifically to clearing or cleaning an underwater object from surface fouling with biological or man-made materials.
The present invention is directed to devices and methods for creating an electric field that can interact with a polar liquid and/or matter contained therein proximate a surface, either directly or by creating a force. The field or force can act to repel, attract, accelerate, vibrate disturb, disperse, deform, detach, displace, abrade and/or remove matter. Some of the many uses can comprise clearing a surface and sanitizing a surface.
The polar material typically comprises water but is also intended to cover any aqueous or other polar composition. Exemplary compositions include but are not limited to pure liquids, mixtures, suspensions, solutions, slurries, and gels, and may include slime, plaque, organisms, organic material, and inorganic material.
Turning now to the figures, FIG. 1 a illustrates an underlying block of the invention, depicting a water drop 50 on a surface 12 a comprising an electric field device (EFD) 500 comprising two electrodes 520, a battery 540 or other voltage source and a switch 560 in an open condition reflective of a device in an off condition. In an off condition, EFD 500 creates no field and therefore exerts no force on drop 50. The profile of the drop 50 is therefore reflective of water physical properties and adhesive interaction with surface 12 a. FIG 1 b depicts EFD 500 on surface 12 a with switch 560 in a closed condition as means of providing a drop-affecting field and resulting in deformed drop 50 a spread/flattened with respect to electrodes 520. Depending on the conditions, the drop 50 may change in other dimensional aspects.
FIGS. 2 a and 2 b illustrate at time t₁and time t₁+Δt an embodiment of EFD 500 comprising a design that can provide voltage to one or more positive condition electrode 520 a and one or more negative condition electrode 520 b, which combination of negative condition and positive condition comprise an electronic displacer 520 c. In some cases, EFD 500 can comprise a construction providing one or more null condition electrode 520 d situated between alternating sets of positive condition electrodes 520 a and negative condition electrodes 520 b. In the figures, each electrode's condition (charge) is depicted as positive (+), negative (−) or null (o), and can be sustained in a time-varying manner. It will be known to those versed in the art that, in the absence of an exerted force, the profile of drop 50 is reflective of water properties and adhesion to EFD 500. In the presence of an electric field generated by EDF 500, force will result in a deformed/flattened drop 50 a with respect to displacer 520 c as depicted at time t₁+Δt. In some cases, the device comprises any type that can provide electrode switching to displaced field and/or force reflective of electronic switching as means of displacing molecules of water.
FIG. 2 b depicts a drop 50 a proximate a plurality of locations 524 on surface 12 a at a plurality of times t=0, 1, 2, 3, and 4. Referring to FIGS. 2 a and 2 b, one or more electrode 520 is mounted with respect to location 524. In some cases, the electrode condition at a location 524 is reflective of switch condition closed (c) or open (o), wherein closed condition can provide a field and open condition cannot. In some cases, a closed condition with respect to one or more locations 524 comprises a displacer 520 c. While presented here in terms of drops and electrodes, the invention is applicable any form of water and to electrode and/or displacer configuration.
At time 0 locations 524 1 through 12 are reflective of an open switch condition so no field is created and drop 50 comprises an undeformed profile. In this example, switch condition is closed with respect to location 524 1, 2, 3, and 4 and open with respect location 524 5 through 10. The field created at locations 524 1, 2, 3, 4 flattens and spreads drop 50 a with respect to locations 524 reflective of closed switch condition. At time 2, switch condition is closed with respect to locations 524 3, 4, 5, 6 and open with respect to locations 524 1, 2, and 7 through 12. At time 3, switch condition is closed with respect to locations 524 5, 6, 7, 8 and open with respect to locations 524 1, through 4 and 7 through 12, again shifting location of field and drop 50 a. It will be seen by those versed in the art that serial change in switch condition with respect to location 524 can provide a translating field and force on water as means of displacing the drop 50 a.
FIG. 3 illustrates an embodiment of an EFD 500 which can generate a field with respect to a plurality of generally linear electrodes 520 connected to a battery 540 by a switch 560 shown here in closed condition reflective of a created field proximate the surface of the surface 12 a that can exert force to provide a deformed drop 50 a reflective of flattening or coalescing as means to reduce fogging and light affecting. In some cases, EFD 500 can further comprise a signal generator 580 of any type that can provide a dynamic signal that can exert dynamic force as means of dislodging, e.g. by vibrating, to provide enhanced draining of water by gravity. In some cases, an EFD can comprise a hydrophobic or superhydrophobic coating of any type that can further enhance draining by gravity. Spacing and dimensions of electrodes 520 can be responsive to desirable force and/or voltages.
In some cases, the EFD 500 comprises one or more conductive elements having an aspect ratio greater than 2.0. Conductive element type comprises at least one of an array, lead, conductor, transistor, switch, insulator, base, amplifier, connector, or other mechanical component. Aspect ratio is defined here as length divided by width in the plane of the clearing surface.
FIG. 4 depicts an antifouling system (“cleaner”) 100 mounted on a periscope head window 12 on a submarine 10. Cleaner 100 can be any type that can create an electric field providing momentum transfer to water proximate window 12 as means of at least one of; antifouling, clearing, and cleaning. In the illustrated embodiment, electrodes 120 are oriented up/down the window 12, although horizontal and other orientations are also acceptable.
Electrodes 120 may be separated and covered by one or more insulating material (not illustrated herein). In some cases, the device comprises a substantially transparent insulation layer providing a desirable degree of electrical insulation reflective of the multiplication product of thickness and dielectric material constant. A material with a high dielectric constant can be used when a thin insulator layer is desirable, e.g. to enhance at least one of transparency, uniformity, flexibility, and manufacturability. In some cases, an electrode material can comprise a compliant composition, such as zinc-tin-oxide, providing device deformability where desired.
Illustrative insulating materials include; silicon dioxide, glass, plastic, Spinel, mineral, ceramic, SU-8, polyimide, air, vacuum or other materials characterized by a desirable diaeletric constant. In some cases, electrodes 120 can comprise a planar disposition, although in some cases electrodes 120 can comprise a dual planar disposition. Spacing among electrodes in any layer or between layers, and thickness of insulating layer, can comprise any magnitude providing a desirable electric field.
In some cases, cleaner 100 comprises any design that can provide an electric field that can affect fouling or other aqueous material directly or via momentum transfer. In some cases, cleaner 100 includes a sprayer 140 of any type such as nozzle, pipe, pump or other type fluid provider that can be mounted proximate the window 12 to provide water, soluablizing agent, or cleaning fluid.
Electrodes 120 can be integrated in or be permanently or reversibly mounted on window 12. In some cases, electrodes can be comprised in an appliqué that can be attached during manufacture, retrofit, or modification of an object. An appliqué is defined herein as any device that can be attached to a head window 12 or other desirably cleared or cleaned surface. In some cases, the appliqué is compliant, wherein compliance provides for attachment of appliqué to a curved surface. One acceptable compliant composition is zinc tin oxide. Attachment is provided by an attachment component of any type, for example glue, magnet, mechanical interlock, chemical adhesion, or fastener of any type. The type of attachment can be at least one of permanent, temporary, controllable, or reversible.
In some cases, cleaner 100 comprises a surface that is more or less flat and/or provides light transmission that is more or less free of attenuation, obstruction, distortion, diffraction, or other alteration. Cleaner 100 can comprise a plurality of electrodes 120 in any configuration that can provide an antifouling field and/or force as means of repelling and/or removing matter, where removing can comprise at least one of disturbing, dislodging, disrupting, dispersing, detaching, or displacing a polar material.
It will be apparent to those versed in the art that cleaner 100 can be integrated into any object as means of antifouling. For example, it can be integrated into buoys, moored platforms, monitoring equipment, viewing port, window, water pipes, building aspect, or infrastructure, as well as any other vehicle or object having at least of portion that is desirable maintained in a cleaned, defogged, or cleared condition.
Cleaner 100 comprises at least one associated component 160, 260 responsive to embodiment or use. Component 160, 260 can be any type including at least one of a circuit, energy source, switch, regulator, signal generator, timer, amplifier, controller, water detector, and/or user interface. Illustrative electricity sources include battery and vessel electrical system. The switch can be of any type comprising one or more element which can be open or closed. In some cases, the switch comprises a plurality of elements that can be switched in one or more spatial and/or temporal combinations. Energy supply or regulator can be any type that can provide a desirable magnitude and/or polarity of voltage to electrodes. In some cases, signal generator comprises any type that can provide a desirably varying voltage. In some cases, controller is any type of device that can provide control for at least one component.
In some cases, a switch is any type that can provide propagating field as means of providing propagating momentum transfer in a desirable direction, e.g. to propel the submarine forward. In some cases, a voltage controller is any type that can provide voltage responsive to desirable magnitude and/or direction of momentum transfer.
In some cases, a switch can be any type that can provide a field pattern yielding momentum transfer across the electrodes, e.g. by providing voltage to electrodes in spatial and temporal sequence that can create a propagating field and thereby exert a propagating force to disturb, disrupt, dislodge, or displace fouling and/or aqueous matter from the periscope head window, although a propagating field type is not required.
In some cases, an electrode 120 comprises at least partly transparent construction and/or composition, although this is not required. Transparent is defined herein as permitting propagation of at least one wavelength of electromagnetic radiation. One transparent construction comprises semiconductor, conductor, metal, or nanostructure electrodes comprising a plane or surface through which a visual image is readily seen. Exemplary materials include oxide formulations of zinc, tin and aluminum (with one acceptable transparent composition among many being indium titanium oxide), carbon nanotubes, or gold, copper, or other conductive materials that can be formed in a layer thin enough to provide transparency. Another acceptable transparent composition is zinc titanium oxide, which is additionally transparent to infrared light. The material may comprise more than one component material, such as carbon nanotubes in a matrix, wherein the matrix can comprises at least one of organic and inorganic constituents. Other compositions transparent to other wavelengths of electromagnetic radiation are also acceptable.
In some cases, transparent construction can comprise some dimensional aspect, wherein dimensions such as electrode width and spacing permit passage of light. One exemplary configuration with a geometric aspect is conductive elements that are narrow and spaced apart such that at least 25% of radiation substantially orthogonal to the clearing face can propagate through the device without striking a conductive element. A second exemplary construction is a conductive element narrower than a desirably propagated wavelength of radiation, e.g. 500 nanometers for certain wavelengths of visible light. One example material aspect is substantial transparency at a desirable wave length, e.g. indium-titanium-oxide for visible light. In some cases, transparency of the electrodes is with respect to visible wavelengths of electromagnetic radiation; in other cases, transparency is with respect to other wavelengths of radiation.
In some cases, the device comprises a non-distorting construction of any type that can provide visual use that is not substantially distorted. For example, electrodes can be mounted in a manner providing a smooth outer surface that does not substantially distort light passing through the device.
In some cases, at least one component of the device is relatively thin, i.e. in a direction substantially orthogonal to the clearing surface. In some cases, the device is deformable, for example to provide conformal attachment to a curved surface. In some cases, at least one component of the device is compliant, defined as relatively distortable without substantial damage. One example is a conductive or array element formed of a compliant material such as zinc-tin-oxide or analogous material.
In some cases, the device comprises a signal generator of any type that can provide a dynamic field, for example one exerting dynamic force that can disturb or dislodge a water drop by inducing vibration that can alter drop adhesion and facilitate draining under the influence of gravity.
In some cases, the device can comprise signal generator and switch in any configuration that can provide dynamic signal to a plurality of electrodes or sequence of pluralities of electrodes for a desirable time or with a desirable duty cycle.
Although the window of a submarine is illustrated herein, those skilled in this art will recognize that the cleaning techniques and structures described herein may be suitable for a clearing surface on any object operable proximate water, including but not limited to vessels, vehicles, machinery, buildings and components thereof. Clearing surface is defined as a surface with respect to which water or other polar material is desirably displaced or deformed. Exemplary surfaces include those of objects such as a window, sensor, transmitter, or receiver intended for operation or use with respect to a desirable wavelength of electromagnetic radiation.
In some cases, the device comprises an actuator that can produce force or torque, which device can be attached to an object on which force or torque is desirably exerted. The object is any type located with respect to a gas-liquid interface, such as the ocean surface, which object is desirably subjected to a force or a torque.
One exemplary object is a toy boat wherein the device is mounted at the stern proximate water surface and aligned in the desired propulsion direction. A second example is a towing actuator comprising a propulsor-type of the device and a connector, such as a rope, providing a mechanical link to a desirably towed object. A third example is rocking-damped ball, buoy, or other float located with respect to the ocean surface, wherein the float comprises one or more units of inventive device, an energy source, a rocking sensor and a controller. A tilt sensor is any type that can detect orientation, or change or rate of change thereof, for example rocking of a buoy due to ocean waves. As a rocking damper, one or more unit of the inventive device is mounted on the float with respect to the ocean surface, and connected to energy source, sensor and controller. Units can be spaced evenly, regularly, unevenly, and/or haphazardly or randomly.
Suitable uses comprise anti-fouling, cleaning, clearing and momentum transfer.
Antifouling can be used to provide or maintain a clean and/or dry surface, reduce drag, enhance fuel economy, and/or provide enhanced maintenance. In some cases, antifouling can be used to provide clean a surface, e.g. boat hull or transducer, such as an electro-optical or infrared sensor or camera exposed to fouling by mud or other sediments splashed onto it during rain. Antifouling can also include cleaning a building, building component, machinery or machinery component. Examples include walls and pipes. Momentum transferring can be used to provide propulsion and/or steering, e.g. of a boat, buoy or towing device.
Antifouling methods can comprise electrical, mechanical, and/or hydrodynamic techniques. An illustrative electrical method comprises creating a field that can at least partly repel and/or retard settling and/or adhering of fouling matter. An illustrative mechanical method comprises creating a dynamic field causing cause vibration of a surface and/or proximate material to create adverse settling conditions and/or to dislodge settled matter of any type. An illustrative hydrodynamic method comprises creating a field that exerts a force on water to provide momentum transfer, e.g. using a water jet or electronic wiper, to drive water over the surface to dislodge or wash away settled matter or water drops.
Methods of use comprise providing electric energy (hereinafter “voltage”) to a plurality of electrode to create an electric field of any type that can interact with polar matter, e.g. water, to provide momentum transferring and/or polar interaction with respect to fouling matter and/or water. Transfer of momentum can be used to provide cleaning, drag reducing, and/or antifouling including drop clearing. Polar interaction can provide a direct affect, e.g. by providing a repelling or detaching influence on organisms.
Additional uses of the device include generating force or torque, for example on an object proximate an air-water interface. A first illustrative use is propulsion of a toy boat. Propulsion is provided by operating a unit of the inventive device mounted, e.g. at the stern of the boat, such that water is displaced and a propulsion force is produced. A second use is towing an object, wherein a towing actuator comprising the inventive device is connected to a desirably towed object such that the device generates a force at the gas-liquid interface that can be transmitted via a connector to the desirably towed object. A third illustrative use is to damp rocking of an object floating at an air-water interface, which rocking can be produced by ocean waves and which damping comprises, sensing tilt, processing the output of the sensor using the controller to determine a torque that can provide a countervailing tilt, and providing a signal the inventive device reflective of the determined torque.
In some cases, field creating can be provided by at least one of switching, regulating, and changing voltage. In some cases, switching comprises switch opening and/or closing with respect to one or more electrode. Regulating can comprise at least one of increasing, maintaining and decreasing voltage. Changing can comprise oscillating amplitude and/or frequency.
Voltage can be switchably provided to a plurality of electrodes and/or sets of electrodes in a desirable temporal relationship, e.g. in sequence or in repeated sequence. In some cases, switchably providing can is used to create a spatially displaced, or propagating, force for continuing water displacing. In some cases, providing comprises voltage regulated providing, e.g. simultaneously providing energy of differing voltage to a plurality of electrodes. In some cases, switchably providing and voltage regulating are temporally coordinated.
In some cases, the method comprises dislodging drops of water, e.g. on the periscope head window, such as by creating a field exerting a dynamic force that can disturb, deform, dispel, displace or dislodge drops and facilitate their draining under the force of gravity. One example comprises using a signal generator to create a dynamic field to disturb water or an aqueous composition, e.g. by vibration, as means of adhesion disturbing.
In some cases, the method comprises providing a polar fluid, dispersant, surfactant or other solvent to a surface with respect to which is desirably cleaned. For example, a sprayer can provide polar fluid, e.g. water, to the periscope head. In some cases, polar fluid comprises soap or other cleaning solution. In some cases, it comprises a component providing desirable properties such as alcohol to prevent freezing.
Energy providing comprises any means that can displace water in a desirable direction. Example directions include across electrodes, along electrodes, or a combination thereof. Force of a desirable magnitude can be exerted by controlling voltage with respect to one or more electrode.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.

Claims

1. A method of clearing a surface of an object contaminated with a polar material, comprising the steps of:

providing an object having a surface with a plurality of spaced apart electrodes, the electrodes being connected with a voltage source and capable of sustaining a time-varying charge;

inducing a first electric field on the plurality of electrodes of a magnitude and for a duration to induce drops of the polar material to take a first dimensional aspect; and

inducing a second electric field on the plurality of electrodes of a magnitude and for a duration to induce the drops of the polar material to take a second dimensional aspect.

2. The method defined in claim 1, wherein the plurality of electrodes are arranged in alternating first and second sets, wherein the first set takes a positive charge under the first electric field and the second set takes a negative charge under the First electric field.

3. The method defined in claim 2, wherein the first set of electrodes takes a negative charge under the second electric field.

4. The method defined in claim 2, wherein the first set takes a neutral charge under the second electric field.

5. The method defined in claim 1, wherein the electrodes are generally linear and extend across the object surface.

6. The method defined in claim 1, wherein the object surface is transparent.

7. The method defined in Clam 1, wherein the polar material comprises water.

8. The method defined in claim 1, further comprising the step of introducing a cleaning fluid to the object surface prior to the inducing steps.

9. A method of clearing a surface of an object contaminated with a polar material, comprising the steps of:

inducing a first electric field on the plurality of electrodes arranged in alternating first and second sets, wherein the first set takes a positive charge under the first electric field and the second set takes a negative charge under the first electric field, the electric field being induced at a magnitude and for a duration to induce a drop of the polar material to take a first dimensional aspect; and

inducing a second electric field on the plurality of electrodes in which at least one electrode in the first set takes a neutral or negative charge and at least one electrode in the second set takes a neutral or positive charge, with the result that the drop of polar liquid moves along the object surface.

10. The method defined in claim 9, wherein each of the electrodes is capable of taking a positive, negative and neutral charge.

11. The method defined in claim 9, further comprising repeating the steps of inducing a first electric field and inducing a second electric field in order to continue to move the drop of polar liquid along the object surface.

12. The method defined in claim 9, wherein the electrodes are generally linear and extend across the object surface.

13. The method defined in claim 9, wherein the object surface is transparent.

14. The method defined in Clam 9, wherein the polar material comprises water.

15. The method defined in claim 9, further comprising the step of introducing a cleaning fluid to the object surface prior to the inducing steps.

16. A method of clearing a surface of an object contaminated with a polar material, comprising the steps of:

inducing a first electric field on the plurality of electrodes arranged in alternating first and second sets, wherein the first set takes a positive charge under the first electric field and the second set takes a negative charge under the first electric field, the electric field being induced at a magnitude and for a duration to induce a drop of the polar material to take a first flattened shape;

ceasing the induction of electric field on the plurality of electrodes, with the result that the drop of polar liquid takes a second relaxed shape;

repeating the inducing and ceasing steps to cause the drop of polar liquid to alternately switch between the first and second shapes and provide a scrubbing action to the object surface.

17. The method defined in claim 16, wherein the electrodes are generally linear and extend across the object surface.

18. The method defined in claim 16, wherein the object surface is transparent.

19. The method defined in claim 16, wherein the polar material comprises water.

20. The method defined in claim 9, further comprising the step of introducing a cleaning fluid to the object surface prior to the inducing and ceasing steps.

21. An object with anti-fouling capability, comprising:

a surface with a plurality of spaced apart electrodes, the electrodes being capable of sustaining a time-varying charge;

a voltage source connected with the electrodes; and

a controller for controlling the voltage of the electrodes, the controller configured to (a) induce a first electric field on the plurality of electrodes of a magnitude and for a duration to induce drops of a polar material on the object surface to take a first dimensional aspect, and (b) induce a second electric field on the plurality of electrodes of a magnitude and for a duration to induce the drops of the polar material to take a second dimensional aspect.

22. The object defined in claim 21, wherein the surface is a transparent surface.

23. The object defined in claim 21, wherein the object is a submersible vehicle.

24. The object defined in claim 21, wherein the electrodes are generally linear and extend across the object surface.

25. The object defined in claim 21, further comprising a source for applying a cleaning fluid to the surface.