Deposit dissipating layer

Described in this disclosure is a surface configured to break down deposits thereon. The surface may include breakdown structures, oleophilic structures, and hydrophilic structures. The oleophilic structures and hydrophilic structures are configured to disperse a deposit, such as fingerprint residue, to the breakdown structures. This dispersion increases the surface area of the deposit with respect to the breakdown structures, increasing the contact area between the two. The breakdown structures modify the deposit physically, chemically, or both, such that fragments are distributed into the ambient environment. The surface may be applied to portable electronic devices.

BACKGROUND

Fingerprints, dirt, and other materials deposited on surfaces may adversely impact the aesthetics, functionality, or both of those surfaces. For example, a fingerprint or other type of smudge on a touchscreen of a portable electronic device may be unsightly and interfere with a user's ability to view an image presented on the touchscreen.

Certain implementations and embodiments will now be described more fully below with reference to the accompanying figures, in which various aspects are shown. However, various aspects may be implemented in many different forms and should not be construed as limited to the implementations set forth herein. Like numbers refer to like elements throughout. The figures are not drawn to scale. Unless otherwise specified relative sizes or proportions between elements of the figures are illustrative and are not to be construed as limiting.

DETAILED DESCRIPTION

Users may physically touch surfaces on a wide variety of objects including portable electronic devices, in-vehicle entertainment or control systems, desktop computers, and so forth. These touches may leave behind deposits, such as fingerprints, smudges, and other materials. These deposits may adversely impact the aesthetics, functionality, cleanliness, and/or any other attribute of the objects. For example, fingerprints and smudges on a touchscreen may adversely impact the ability of the user to clearly see images presented on the screen.

Described in this application are examples of surfaces comprising structures which disperse and break down the deposits into fragments, providing a self-cleaning effect. These structures may be comprised of materials which are oleophilic, hydrophilic, or both. This surface may have one or more layers which may be applied to, or integrated with, the objects such as portable electronic devices. The surfaces described in this disclosure have a thickness greater than zero. Within this thickness, the surface may include one or more layers, one or more different materials or structures, or a combination thereof. For example, the surface may comprise a film, a layer having interspersed structures, and so forth.

The breakdown of the deposit may involve chemical processes, physical processes, or a combination thereof. Once broken down, the resulting fragments may fall away from the surface, volatilize into the ambient atmosphere, or otherwise be distributed into the environment. In some implementations at least a portion of the resulting fragments may remain within the surface.

One or more dispersion layers may be operable to or may be configured to disperse the deposit across a portion of a breakdown layer. The dispersion increases surface area of the deposit in contact with the breakdown layer. This increased surface area allows the breakdown layer to interact with more of the deposit. This may improve breakdown of the deposit, reduce time to break down the deposit, and so forth.

The dispersion layers may include one or more materials. These materials may be hydrophilic materials, oleophilic materials, or a combination thereof. In one implementation, the dispersion layers may comprise a layer of hydrophilic material arranged atop a layer of oleophilic material, which in turn is atop the breakdown layer. The dispersion layers may include one or more dispersion structures. For example, the dispersion structure may comprise a mesh incorporating hydro- and oleo-philic materials. The dispersion layers are configured to distribute the deposit across the breakdown layer. In some implementations, functionality of the dispersion layers may be incorporated into the breakdown layer.

The breakdown layer may operate through one or more mechanisms. In one implementation, photocatalysis may use energy from photons provided by a light source to generate chemical species such as free radicals which chemically react with the deposit. These chemical species may be generated from reactants in the ambient atmosphere, the deposit itself, the breakdown layer, or a combination thereof.

The breakdown layer renders the deposit into fragments which may be dispersed into the ambient environment. For example, chemical reactions may change a portion of the deposit into material which is more volatile and will outgas more readily to the ambient environment. Other chemical reactions may break the deposit into fragments which may then dissipate to the ambient environment.

By dispersing and breaking down the deposit, the surface may improve the aesthetics, hygiene, or other aspects of the object. For example, microbes may be broken down by the surface, reducing the possible transfer of disease. Furthermore, usability of the object may be improved during operation by reducing or eliminating impact of the deposit. For example, by breaking down fingerprints and smudges until they dissipate, the user may be better able to see information presented on a touchscreen.

Illustrative Devices

FIG. 1is an illustrative system100. A portable electronic device102is depicted. The portable electronic device102(“device”) may be a tablet computer, smartphone, portable content player, eBook reader, medical device, piece of instrumentation, and so forth. The device102is portable in that a user may hold the device102or readily relocate the device102from one location to another.

The device102has an enclosure104, such as an integral case, cover, and so forth. The device102may also have a display106, configured to provide visual information such as displayed content108to the user. The display106may have a front or a top, through which the user is able to see the displayed content108. In some implementations, the display106may be combined with some mechanism to detect a touch thereto, such as a touch sensor, camera, and so forth, to form a touchscreen.

A surface110may be applied to, or formed as part of, one or more of the enclosure104, the display106, and so forth. As described above, the surface110has a thickness which is greater than zero. For example, the surface110may be greater than one picometer thick. The surface110is configured to accept contact with an external object, such as a finger112or other part of a user's hand. The external object may transport or exude materials, which may be transferred to the surface110, forming a deposit114. The transfer may result from contact, proximity, and so forth. For example, the deposit114may comprise material from the tip of the finger112, such as exudate produced by the eccrine glands of the finger112. The deposit114may manifest as a fingerprint, smudge, droplet, splash, spill, and so forth. The deposit114may comprise one or more of organic or in-organic components.

The surface110is operable to process the deposit114such that it is broken down into fragments, chemically reacted with, and so forth. The surface110may include a breakdown layer. In some implementations, the breakdown layer may comprise titanium dioxide operable to provide photocatalysis120when illuminated by ultraviolet light. As illustrated here, a light source116such as the sun, room lights, or an illuminator built into the device102, provide photons118to the breakdown layer of the surface110. These photons118may provide the energy for the photocatalysis120to occur in the breakdown layer of the surface110. As photocatalysis120proceeds, the deposit(s)114may be broken down into fragments or otherwise reacted such that they no longer are apparent to the user. The surface110is disclosed in more detail in the figures below.

The surface110may be configured to be opaque, or at least partially transparent or translucent to one or more wavelengths of visible light. For example, the surface110as used atop the display106is configured such that the displayed content108is visible to the user during operation. In one implementation, the surface110may be transmissive to at least 60% of one or more visible wavelengths incident upon the surface110. The surface110may not be uniformly transmissive to all wavelengths of visible light. For example, the surface110may exhibit higher transmissivity at red wavelengths compared to blue.

In another implementation the surface110may be opaque or at least partially transmissive to non-visible light. For example, when used atop an optical fingerprint reader device, the surface110may be transparent to one or more wavelengths of non-visible light, such as near-infrared or ultraviolet used by the fingerprint reader device.

In other implementations, the surface110may be configured to be opaque to one or more wavelengths of visible light, non-visible light, and so forth. For example, the surface110may be arranged atop the enclosure104of the device102, such as on one or more of the bezel, sides, or back. As the user handles the portable electronic device102and imparts deposits114on the surface110, the deposits114are broken down. As described above, this improves the aesthetics and may also improve safety by preventing the surface110from remaining slippery due to an accumulation of the deposits114.

The surface110may also be operable to be reflective at one or more wavelengths. For example, the surface110may be operable to be reflective to infrared wavelengths.

In addition to the device102, the surface110may be used on other objects. For example, the surface110may be applied to tabletops, door handles, and so forth.

FIG. 2illustrates a cross section200of the surface110along the line “A-A” as depicted inFIG. 1. The cross section200depicts the display106and other internal circuitry202of the portable electronic device102, such as a processor, memory, battery, and so forth. The surface110is depicted as covering the exterior of the device102. In other implementations the surface110may cover the display106or portions of the exterior except for the display106. For example, the surface110may be configured to cover the back and sides of the device102, leaving the display106uncovered. The surface110may be applied by way of coating, physical vapor deposition, chemical vapor deposition, as a film, as a fabric, and so forth.

Depicted here is an enlarged view204of a portion of the surface110. In the enlarged view204an oleophilic layer206is depicted. The oleophilic layer206is includes oleophilic materials which exhibit an affinity for oil-based materials. This affinity may use one or more of molecular or chemical characteristics of the oleophilic materials, physical characteristics, such as size and shape, or any combination to provide the affinity. The oleophilic materials may include, for example, hydrocarbons, thermoplastics, polycarbonate, polyvinylchloride, polymer materials, such as PET (polyethylene terephthalate), PP (polypropylene), PTFE (polytetrafluoroethylene) and PVDF (polyvinylidene fluoride), any other type of materials having an affinity for oils or combination thereof. Additionally or alternatively, the material may be treated (e.g., coated) to become oleophilic, be naturally oleophilic, or combination thereof. The oleophilic layer206may be arranged proximate to a hydrophilic layer208. Proximity may include adjacency, abutment, contact, and so forth between two objects. For example, the oleophilic layer206may be adjacent to the hydrophilic layer208. In some implementations, the oleophilic layer206or other oleophilic structures described herein may include a plurality of different oleophilic materials.

The hydrophilic layer208includes hydrophilic materials which exhibit an affinity for aqueous or water-based materials. The hydrophilic materials may include polymers comprising hydroxyls, acids, oxides, or organic salts. In some implementations, the hydrophilic layer208or other hydrophilic structures described herein may include a plurality of different hydrophilic materials

Affinity of one material for another material may be measured as a surface contact angle. The surface contact angle may be obtained by placing a droplet of a probe liquid, such as an oil- or water-containing compound, on a material under test. A contact angle may be described as an angle between the surface of the material under test, through the droplet, and a tangent of the droplet's ovate shape at an edge of the droplet. In one implementation, measurement of the contact angle may comprise applying a drop of the probe liquid to the surface of the material and measuring an angle between the surface and the tangent of the droplet using a contact angle goniometer with a microscope or camera for visualization of the drop. The contact angle may also be described using the static sessile drop method, dynamic sessile drop method, dynamic Wilhelmy method, and so forth.

A high contact angle may be indicative of a low solid surface energy or chemical affinity for the material in the droplet. For example, a probe liquid of pure water placed on a material such as polytetrafluoroethylene (“PTFE”) may exhibit a water contact angle of about 110 degrees. PTFE may be considered “hydrophobic”. Conversely, a low contact angle may be indicative of a high solid surface energy or chemical affinity. For example, a probe liquid of pure water placed on a material such as poly(methyl methacrylate) (“PMMA”) may exhibit a water contact angle of about 68 degrees. PMMA may be considered “hydrophilic”. In one implementation, the contact angle may be determined using a system such as the VCA Optima™ by AST Products Inc., of Billerica, Mass.

Other probe liquids may be used to characterize the material. For example, squalene and/or other oil-based compounds may be used to determine oil contact angles. The oil contact angle is indicative of the affinity of the material to oil-based compounds. As used in this disclosure, a material is deemed to be “-philic” for a probe liquid when the contact angle is less than about 100 degrees, and “-phobic” when the contact angle is greater than 100 degrees.

In accordance with some example embodiments discussed herein, the oleophilic layer206or oleophilic material described in this disclosure may be characterized by an oil contact angle for a squalene-based material of less than 40 degrees. The hydrophilic layer208or hydrophilic material in this disclosure may have a water contact angle of less than 100 degrees.

The oleophilic layer206is proximate to the hydrophilic layer208. The hydrophilic layer208, in turn, may be proximate to the breakdown layer210. As described above, proximity may include adjacency, abutment, contact, and so forth between two objects. The breakdown layer210, in turn, is proximate to a barrier layer212. In another implementation the oleophilic layer206may be proximate to the breakdown layer210, while the hydrophilic layer208is atop the oleophilic layer206.

The barrier layer212is impermeable to water- and oil-based materials. For example, the barrier layer212may comprise a glass, plastic, metal, ceramic, composite, and so forth. In some implementations the barrier layer212may be used as a substrate upon which the breakdown layer210may be deposited or coupled to during manufacturing. In some implementations, the barrier layer212may be omitted, while in others the barrier layer212may comprise another structure, such as a portion of a display device, exterior plastic of a housing or case, and so forth.

The breakdown layer210is configured to render the deposit114such that pieces thereof may be dispersed into the ambient environment. The breakdown layer210may use one or more mechanisms to produce these pieces. For example, the breakdown layer210may comprise nanostructures formed from titanium dioxide. These nanostructures are configured to support photocatalysis120, using as reactants the ambient environment, the deposit114, or both. The photocatalysis120may use the photons118to energize the reaction. The breakdown layer210is discussed in more detail below with regard toFIG. 3.

The deposit114may come in contact with the upper or outer layer of the surface110. The oleophilic layer206and the hydrophilic layer208are configured to disperse or distribute at least a portion of the deposit114such that surface area of the deposit114is increased relative to a first surface area at a time of contact with the surface110. In this illustration, deposit dispersion214is indicated as the deposit114spreads out. This increase in surface area increases the area of the breakdown layer210which is in contact with the deposit114, thus providing additional opportunity for the deposit114to be broken down by the action of the breakdown layer210.

For ease of illustration, and not necessarily as a limitation, the portion of the surface110which is configured to distribute the deposit114may be designated a dispersion layer(s)216. In this illustration, the dispersion layer216comprises the oleophilic layer206and the hydrophilic layer208. The dispersion layer216is proximate to the breakdown layer210, which in turn is proximate to the barrier layer212. In some implementations, the dispersion layer216, the breakdown layer210, and the barrier layer212may be laminated or otherwise bonded to one another to form the surface110. In other implementations, such as described below with regard toFIG. 4, functions of the dispersion layer(s)216may be integrated into the breakdown layer210.

The dispersion layer216illustrated here and below is depicted with a single oleophilic layer206and a single hydrophilic layer208for ease of illustration, and not necessarily as a limitation. In some implementations the dispersion layers216may include a plurality of oleophilic layers206, hydrophilic layers208, or both. For example, the dispersion layers216may comprise a first oleophilic layer206(1) proximate to a first hydrophilic layer208(1) which in turn is proximate to a second oleophilic layer206(2) proximate to a second hydrophilic layer208(2), and so forth.

A second view depicts the deposit114as dispersed218by the dispersion layer(s)216. In this view, the deposit114has been drawn into and is now below the surface of the dispersion layer(s)216. In some implementations, the surface110may now appear to be noticeably cleaner. Meanwhile, the breakdown layer210may be breaking down the deposit114.

The dispersion layer(s)216may be configured to provide an index of refraction which is similar to that of the deposit114. For example, the index of refraction for the dispersion layer216may be 1.4, approximately the same as that of human fingerprints. Matching the indices of refraction may reduce visibility of the deposit114.

The surface110may also be configured to provide other characteristics, such as antiglare, antireflection, and so forth. These characteristics may be provided by configuring one or more of the dispersion layer(s)216, the breakdown layer210, the barrier layer212. For example, thickness of the oleophilic layer206may be adjusted to provide an antireflective effect to one or more wavelengths of incident light.

Fabrication of the surface110may include one or more of lamination, chemical vapor deposition, physical vapor deposition, sputtering, painting, or other type of coating process. For example, the breakdown layer210may be applied as a coating onto the barrier layer212, followed by the hydrophilic layer208and the oleophilic layer206. In another implementation, fabrication may include introduction of structures, such as described below with regard toFIG. 4.

FIG. 3illustrates examples300of the breakdown layer210interacting with the deposited material114. Cross sectional views of the deposited material114before breakdown302and after breakdown304are depicted.

Before breakdown302, deposit particles306are shown in contact with the surface of the breakdown layer210. In some implementations the deposit particles306may be proximate to, but not necessarily in contact with, the breakdown layer210. In some implementations the deposit114may be broken into deposit particles306using one or more of the dispersion layers216, configuration of the breakdown layer210, and so forth. For example, in one implementation the breakdown layer210may comprise surface features configured to direct the deposit114into deposit particles306.

As described above, the breakdown layer210is configured to modify the deposit114. The modification may include physical disassociation or breaking up the deposit particles306into fragments308. These fragments308may then be dissipated into the ambient environment through outgassing, mechanical displacement, motion of the surface110, and so forth. For example, the fragments308may volatilize and outgas to the ambient atmosphere. In some implementations, at least a portion of the fragments308may be retained within the surface110. For example, some fragments308may remain within the dispersion layer(s)216.

The fragments308may comprise the same compound(s) as the deposit particles306, such as where the breakdown layer210operates to mechanically fragment the deposit particle306. The fragments308may comprise compounds which chemically differ from the deposit particles306, such as where the modification includes a chemical reaction. For example, the breakdown layer210may produce free radicals such as hydroxyl radicals (OH) which chemically react with one or more compounds in the deposit particles306. This chemical reaction may result in a mechanical fragmentation of the deposit particles306.

The breakdown layer210may comprise one or more materials. These materials may include a catalyst or catalytic material configured to facilitate chemical reactions suitable for breakdown of the deposit particles306. This catalyst may be activated by one or more mechanisms. As described above, the breakdown layer210may be configured to use incident photons118in a photocatalytic120reaction. For example, incident ultraviolet photons118may energize a reaction using titanium dioxide in the breakdown layer210to produce free radicals which may then chemically react with the deposit particles306.

Heat310may also be used to supply energy for breakdown of the deposit particles306. For example, thermocatalysis may take place on the breakdown layer210using heat310generated by operation of the portable electronic device102.

In some implementations the breakdown layer210may utilize electricity312to break down the deposit particles306. For example, an electrolytic reaction may break apart the deposit particles306.

The breakdown layer210may be operable to emit material314. For example, the breakdown layer210may be operable to emit ions which may then react with the deposit particles306. For example, the breakdown layer210may be doped with, or otherwise include, compounds operable to release ions. Continuing the example, the emitted material314may comprise silver ions which are reactive with at least a portion of the deposit114. In some implementations release of the emitted materials314may be controlled using heat310or electricity312.

The breakdown layer210may be configured to use one or more of the mechanisms described above. For example, photocatalysis120may be used in conjunction with electricity312and emitted material314to facilitate break down of the deposit particles306.

In some implementations the breakdown layer210may have other characteristics. For example, the breakdown layer210may comprise one or more antimicrobial materials, such that microorganisms such as bacteria, viruses, and so forth are destroyed or damaged during the break down process.

FIG. 4illustrates a cross section400of a variant of the surface110depicted inFIG. 2. The cross section is along the line “A-A” as depicted inFIG. 1. Depicted here is an enlarged view of a portion of the surface110.

In this implementation the breakdown layer210comprises a plurality of breakdown structures402and one or more of a plurality of oleophilic structures404or hydrophilic structures406. As illustrated here, the one or more breakdown structures402, the one or more oleophilic structures404, and the one or more hydrophilic structures406are interspersed with one another. This interspersion may be regular or may be amorphous. For example, regular interspersion may comprise an ordered repeating pattern such as breakdown structure402, oleophilic structure404, hydrophilic structure406, which then repeats. Regular interspersion may be provided by selective emplacement, self-assembly, and so forth. In comparison, amorphous distribution or interspersion is depicted here, in which the placement of the various structures is unordered.

The breakdown structures402may include catalytic materials. In one implementation the breakdown structures402may comprise nanoparticles of titanium dioxide operable to support catalysis. Other materials such as metals operable to emit ions may also be included.

The oleophilic structures404comprise one or more oleophilic materials as described above. The hydrophilic structures406comprise one or more hydrophilic materials as described above. In some implementations the oleophilic structures404and the hydrophilic structures406may be combined to form a single structure. In some implementations combined oleo-hydro-philic408structures may also be used. These structures may comprise amphiphilic materials. Amphiphilic materials possess both hydrophilic and oleophilic properties. These oleo-hydro-philic structures408may provide be configured to provide some hydrophilic action as well as some oleophilic action. The oleo-hydro-philic structures408may comprise surfactants, amphiphiles, and so forth. In one implementation, the oleo-hydro-philic structures408may comprise polyoxyethylene coupled to one or more other molecules.

The relative positioning of the structures in the breakdown layer210as depicted here may be maintained by way of a matrix. The matrix is configured to be porous to the deposit114. The matrix may comprise a polymer, an aerogel, a sol-gel, a xerogel, a template material, composite material, and so forth. For example, the matrix may comprise a thermoplastic, thermoset polymer, acrylate, polycarbonate, and so forth. In some implementations the polymer matrix may have a low to medium density of cross-links between polymer chains.

For example, the matrix may comprise a silica-based aerogel into which the structures have been placed during or after manufacture. In another example, the structures may be added to liquid silicone rubber, which may subsequently harden with the structures encapsulated within. In another example, during the production of the matrix comprising a template material, one or more of the breakdown structures402, the oleophilic structures404, or the hydrophilic structures406may be infused into the matrix.

In operation, the breakdown layer210depicted here draws the deposit114into the Interstices of the matrix. The deposit dispersion214may be aided by the oleophilic structures404and the hydrophilic structures406. The breakdown structures402proximate to the deposit114, either within the matrix or on the surface thereof, proceed to break down the deposit114as described above.

FIG. 5illustrates a variation500of the surface110comprising a dispersion structure. The cross section is along the line “A-A” as depicted inFIG. 1. Depicted here is an enlarged view of a portion of the surface110.

In this implementation, the dispersion layer216comprises a dispersion structure502. The dispersion structure502is configured to accept initial contact with the deposit114. Proximate to the dispersion structure502is the breakdown layer210. The breakdown layer210, in turn, is proximate to the barrier layer212.

The dispersion structure502may comprise a two- or three-dimensional structure which is configured to provide the deposit dispersion214. In one implementation the dispersion structure502may include a mesh, grid, interlocking space filling array, and so forth. The dispersion structure502comprises one or more materials. These materials may be oleophilic, hydrophilic, amphiphilic, oleophobic, hydrophobic, or a combination thereof. For example, the dispersion structure502may comprise a mesh having oleophilic material arranged in columns and hydrophilic material arranged in rows. In some implementations an ordinarily phobic material may exhibit philic properties at least in part because of the structure. For example, an oleophobic material formed into a mesh may operate in an oleophilic fashion.

The dispersion structure502may comprise features between nanometer and micrometer sizes. For example, the dispersion structure502may comprise a nanomesh. The nanomesh may comprise a nanostructured two-dimensional material. The nanomesh may be formed by way of self-assembly techniques. The structure of the nanomesh may include nanometer-scale pores. For example, each pore in the nanomesh may be approximately 2 nanometers in diameter. The nanomesh may support nanocatalysis. In some implementations, the dispersion structure502may include a plurality of structures. These structures may include one or more meshes, features, grids, honeycombs, pillars, fractal features, and so forth. In one implementation the structures may comprise nanomeshes. For example, a first nanomesh may be configured to act oleophilically while a second nanomesh may be configured to act hydrophilically.

The dispersion structure502may be fabricated using lithography, embossing, chemical action, molecular self-assembly, and so forth. For example, the dispersion structure502may be formed by photolithographic techniques.

FIG. 6illustrates a cross section600of one implementation of the dispersion structure502. The cross section is along the line “A-A” as depicted inFIG. 1. Depicted here is an enlarged view of a portion of the surface110.

In this illustration, the dispersion structure502comprises hydrophilic structures602and oleophilic structures604interspersed with one another. As shown in this example, the oleophilic structures604and the hydrophilic structures602are generally parallel to one another and arranged within a common plane.

In some implementations the dispersion structure502may be configured such that there is a space or gap between portions of the dispersion structure502and the breakdown layer210. This may provide additional surface area on the breakdown layer210for the deposit114to be dispersed to.

In another example, these oleophilic structures604and hydrophilic structures602may comprise strands in a mesh. The oleophilic structures604comprise an oleophilic material. The hydrophilic structures602comprise a hydrophilic material. For example, the structures602-604may comprise a core coated with the corresponding hydrophilic or oleophilic material.

In some implementations a single structure may have a first portion which is hydrophilic and a second portion which is oleophilic. For example, one portion of the dispersion structure502may be hydrophilic while another portion is oleophilic.

In some implementations the dispersion structure502may comprise the oleo-hydro-philic material which is both hydrophilic and oleophilic. For example, the dispersion structure502may comprise a material having a water contact angle of about 100 degrees or less and an oil contact angle for squalene of 100 degrees or less. The dispersion structure502may be configured with channels or other features configured to elicit the deposit dispersion214across the breakdown layer210.

FIG. 7illustrates a cross section700of another implementation of the dispersion structure502. The cross section is along the line “A-A” as depicted inFIG. 1. Depicted here is an enlarged view of a portion of the surface110.

In this illustration, the dispersion structures502comprise features proximate to or joined with the breakdown layer210. A crenellated pattern is illustrated, with the crenellations comprising a hydrophilic structure702comprising a hydrophilic material and an oleophilic structure704comprising an oleophilic material. As described above, the dispersion structures502are configured to distribute the deposit114across the breakdown layer210.

In another implementation, the crenellations may comprise a discrete hydrophilic structure702separated from the oleophilic structure704by a distance. For example, these features may be arranged in a “checkerboard” pattern, alternating in two dimensions across the surface of the breakdown layer210.

In some implementations the dispersion structure502may comprise electrodes. These electrodes may be configured to apply electricity312to aid in electrocatalysis or other mechanisms to break down the deposit114.

FIG. 8illustrates a cross section along the line “A-A” as depicted inFIG. 1of another implementation800of the surface110. In this implementation, the dispersion layer216comprises a combined oleo-hydro-philic layer802(“combined layer”). The combined layer802may comprise both oleophilic material and hydrophilic material. For example, oleophilic particles and hydrophilic particles may be placed into a matrix which is permeable to the deposit114. The combined layer802is configured to provide deposit dispersion214of the deposit114so as to increase the surface area of the deposit114proximate to the breakdown layer210.

In implementations where the breakdown layer210uses photocatalysis120, the photons118used to activate the reaction may be provided at least in part from a light source116which is part of the device102. For example, the light source116may comprise one or more illuminators such as light emitting diodes or quantum dots coupled to an illumination control module804. The illumination control module804may be configured to receive a signal, and based on that signal, activate the one or more illuminators. The illuminators may be configured to emit ultraviolet light suitable to produce the photocatalysis120with titanium dioxide in the breakdown layer210. In other implementations, the illuminators may provide photons118of other wavelengths as used to activate the breakdown layer210.

A light distribution layer806may be coupled to the barrier layer212(or the breakdown layer210where the barrier layer212is omitted) and to the light source116. The light distribution layer806is configured to distribute photons118from the light source116across the breakdown layer210. The light distribution layer806may provide a uniform distribution, or the distribution may provide higher photon levels118at particular points or regions on the breakdown layer210. The light distribution layer806may use refraction, reflection, diffraction, and so forth to distribute the light. In some implementations the light distribution layer806may be omitted and the light source116may illuminate the breakdown layer210directly. In some implementations the light source116may also act as a backlight or a front light to a display106.

FIG. 9illustrates a sequence900of the deposit114on the surface110over time. In this illustration, time increases down the page as indicated by the arrow902.

At time=1, the deposit114is placed on the surface of the surface110. For example, the finger112may have touched the surface of the surface110which is atop the enclosure104. This touch leaves behind a deposit114, such as a fingerprint. The deposit114interferes with the appearance of the surface110. For example, the fingerprint may be visible.

At time=2, the deposit114is dispersed by the dispersion layer(s)216. As described above, the deposit114having a width “W1” at the time of deposition may be drawn into the dispersion layer(s)216, at least until those layers are saturated. At this point, the deposit114may be much less apparent to the user. For example, the fingerprint may appear to fade.

At time=3, dispersion continues, the deposit particles306of the deposit114are proximate to the breakdown layer210or breakdown structures402, and breakdown begins. As indicated, the deposit114may have spread out, as indicated by width “W2”. For example, the photons118may activate the photocatalysis120such that free radicals produced thereby begin to disassociate the deposit particles306into fragments308.

At time=4, the breakdown continues. The dispersion layer(s)216may also continue to disperse the deposit114, increasing the surface area thereof and thus increasing the quantity of the deposit114which are reacted with by the breakdown layer210or the breakdown structures402. The deposit114continues to break down into deposit particles306which may be outgassed, or which fall away from the surface110, leaving the surface110clean.

At time=5, the breakdown is complete and the fragments308have been dissipated. While some deposit particles306or fragments308may remain, the majority have been removed from the surface110. As a result, the deposit114is much less visible to the user, or may be gone completely. The surface110may now appear to be clean, and the user experience is improved.

FIG. 10is a flow diagram1000of a process of assembling the surface110by way of molding. The process may be performed manually, automatically, or by a combination of manual and automatic steps.

In some implementations, the surface110, or an object which will incorporate the surface110such as the enclosure104, may be created by molding. For example, injection molding may be used to create the surface110which may then be applied to the enclosure104. In another example, the enclosure104may be formed using injection molding at which time the surface110as described above may be formed.

At1002, breakdown structures402are introduced into at least a portion of a mold. In one implementation the breakdown structures402may be blown into the mold as a powder. In another implementation, the breakdown structures402may be dispersed within the mold as a liquid. In one implementation the breakdown structures402may comprise titanium dioxide nanoparticles. In some implementations one or more other structures such as the oleophilic structures404, the hydrophilic structures406, and so forth may also be introduced into the mold. Furthermore, in some implementations the various structures may be introduced in a particular order so as to generate particular layers or structures within the resulting surface110. For example, the oleophilic structures404and the hydrophilic structures406may be introduced into the mold first, followed by the breakdown structures402.

At1004, matrix material is placed within the mold. The matrix material may comprise a liquid, powder, granulated material, solid, and so forth. For example, the matrix material may comprise liquid silicone rubber which is pumped or poured into the mold.

In some implementations additional mechanisms may be used to distribute one or more of the structures throughout the matrix material. These may include centrifuging the mold, applying an electrical field, applying a magnetic field, applying a temperature gradient, and so forth.

At1006the matrix material is solidified, incorporating at least a portion of the breakdown structures402, the oleophilic structures404, and the hydrophilic structures406and Introduced into the mold. Thus, the matrix material acts to retain at least a portion of the structures introduced into the mold. Solidification of the matrix material may include curing or other processes such as application of pressure, light, heat, electricity, waiting, and so forth. In some implementations the structures may act as a release agent to separate the matrix material of the now formed surface110from a surface of the mold.

In some implementations additional operations may be performed. For example, the now solidified material which forms the matrix may be processed to introduce interstices or pores through which the deposit114may travel to come into contact with the breakdown structures402retained therein.

FIG. 11is a flow diagram1100of a process of creating the surface110by way of coating. Coating may include the process of applying one or more materials to a surface by way of a spray, mist, brush, electroplating, electrostatic charge, electrophoretic coating, liquid coating, and so forth. In one example, the coating may employ a material in a solvent or carrier material, such as in electrophoretic deposition in which colloidal particles are suspended in the solvent and migrate under the influence of an electric field. In another example, no solvent or carrier may be employed, such as in powder coating.

At1102, a substrate is prepared for application of material. The preparation may include one or more of application of a primer, cleaning, sanding, and so forth. The substrate may comprise a portion of the enclosure104, the barrier layer212, the breakdown layer210, or other structure.

At1104a first coat of material is applied to at least a portion of the substrate. The first coat of material may comprise breakdown structures402. In some implementations the first coat may be cured before proceeding to1106.

At1106a second coat of material is applied to at least a portion of the first coat of material. The second coat of material may comprise one or more of the oleophilic structures404, the hydrophilic structures406, or structures which are both oleophilic and hydrophilic.

At1108, one or more of the first coat or the second coat cure. The curing may include the use of heat, light, moisture, waiting, application of another material, and so forth. For example, the surface110may be illuminated with ultraviolet light for a predetermined period of time to cure the materials.

In some implementations, an additional coat or layer of material porous to the deposit114may be applied. The additional coat may modify abrasion resistance of the surface110, change the color of the surface110, and so forth. Additionally, in some implementations a single coat or more than two coats of material may be applied to the substrate.

FIG. 12is a flow diagram1200of a process of activating the breakdown layer210using one or more signals. The portable electronic device102may perform the process.

Block1202determines a predetermined number of touches to a surface comprising the surface110. For example, an input control may determine that 95 touches have been made to the surface110based on touch sensor input. As described above, the surface110includes a dispersion layer216and a breakdown layer210.

Block1204generates one or more signals configured to activate the breakdown layer210. This generation may be based on the predetermined number of touches having been reached or exceeded. For example, a processor may be configured to generate an interrupt signal which in turn activates circuitry controlling the light source116in the device102, such as described inFIG. 8. In another example, the interrupt signal may activate circuitry controlling the application of heat310, electricity312, emission of material314, and so forth as described above with regard toFIG. 3.

Block1206breaks down one or more deposits114on the surface110based on activation of the breakdown layer210by the one or more signals. For example, the deposit114may be broken down by photocatalysis120which is activated by the photons118produced by the light source116which has been turned on by the interrupt signal.

In another implementation, a timer may be used such that the generation of the one or more signals occurs after a predetermined amount of time that the device is in operation. In yet another implementation, a sensor may detect the deposit(s)114on the surface110and based on that detection generate the one or more signals.

Those having ordinary skill in the art will readily recognize that certain steps or operations illustrated in the figures above can be eliminated or taken in an alternate order. Moreover, the methods described above may be implemented as one or more software programs for a computer system and are encoded in a computer readable storage medium as instructions executable on one or more processors.

The computer readable storage medium can be any one of an electronic storage medium, a magnetic storage medium, an optical storage medium, a quantum storage medium and so forth. Separate instances of these programs can be executed on or distributed across separate computer systems. Thus, although certain steps have been described as being performed by certain devices, software programs, processes, or entities, this need not be the case and a variety of alternative implementations will be understood by those having ordinary skill in the art.

Additionally, those having ordinary skill in the art readily recognize that the devices and techniques described above can be utilized in a variety of devices, environments and situations.

Although the present disclosure is written with respect to specific embodiments and implementations, various changes and modifications may be suggested to one skilled in the art and it is intended that the present disclosure encompass such changes and modifications that fall within the scope of the appended claims.