WO2015144918A1 - Micropits for ultrasonic treatment - Google Patents

Abstract

The invention provides a method for treating an object (100), the method comprising: (a) providing a liquid (210); (b) arranging the object (100) in the liquid (210), wherein the object (100) is at least partially enclosed in an enclosure (300), wherein the enclosure (300) comprises polymeric enclosure material (310) having a polymeric material surface (320) directed to the object (100), the polymeric material surface (320) comprising cavities (330) having equivalent circular diameters selected from the range of 10 μm - 2 mm; and (c) providing ultrasound to the liquid (210).

Description

Micropits for ultrasonic treatment

FIELD OF THE INVENTION

The invention relates to a method for treating an object to bubbles, such as to ultrasonic cavitation. The invention further relates to a layer and an enclosure (comprising such layer) that may be applied in the method, and the use of the enclosure for subjecting a solid (or liquid) material to ultrasound. BACKGROUND OF THE INVENTION

The use of ultrasound is known in the art. EP2315235, for instance, describes a method and apparatus for cleaning semiconductor substrates, wherein a nucleation structure is mounted facing a surface of the substrate to be cleaned, said nucleation structure having nucleation sites on a surface of the structure. The substrate and structure are brought into contact with a cleaning liquid, which is subsequently subjected to acoustic waves of a given frequency, e.g. megasonic waves. The nucleation template features easier nucleation formation than the surface that needs to be cleaned. This could be obtained in different ways: make a template with a higher contact angle when in contact with the liquid than the substrate surface to be clean. Therefore, bubbles nucleate on the structure and not on the surface to be cleaned. EP2315235 describes an apparatus comprising a tank, a transducer and a means for mounting the substrate and nucleation structure in the above manner.

SUMMARY OF THE INVENTION

Ultrasound irradiation of liquids is widely used for cleaning in various industries, including e.g. the manufacturing industry, the health care industry, etc.. Its uses range from e.g. cleaning jewelry and dental instruments, wafers in the computer industry, metal parts, but ultrasound irradiation may also be used for surface treatment, atomization and emulsification. Ultrasound irradiation is herein also indicated as "ultrasonic cavitation", since ultrasonic cleaning relies on the formation and collapse of bubbles (cavitation) due to ultrasound (sound with frequencies above the audible regime of about 20 kHz). These bubbles may generate several physical effects (such as streaming, jetting and Shockwaves, plasma, light emission, etc.) and chemical effects (radical formation such as ΌΗ, ·ΝΟ_χ) that appear to be useful for instance for the cleaning of various objects and substrates. Bubbles are also involved in other ultrasonic liquid processes, including atomization, emulsification and modification of surfaces (increasing roughness, surface activation). Furthermore, ultrasonic cavitation has been used for water treatment, particle atomization, liquids emulsification and synthesis of nanomaterials.

The use of bubbles to actuate or modify the environment of cells, and other biological applications, has gained the attention of the scientific and industrial community. Applications include drug uptake and cell membrane lysis. Recently, the food industry has shown an interest in using ultrasound in certain processes such as dairy product modification. Alternatively to the collapse of bubbles, it has been shown that injection of bubbles and their subsequent sonication can improve existing processes such as washing and chemical reactions.

The existing ultrasonic technology relies on the appearance of bubbles from defects or crevices (nuclei) in the walls of a container or dissolved motes in the bulk liquid. However, the amount and location of these nuclei usually cannot be controlled. Furthermore, in ultrasonic cleaning, there are often difficult-to-access places such as inside hollow instruments (e.g. endoscopes) that are difficult to access with ultrasound. Often, an expensive large volume of liquid such as acetone, or the use of additional detergents are needed, which is not economically nor environmentally favorable. Electrical-to-mechanical conversion efficiencies are not higher than 10^~6, rendering ultrasonic cleaning slow or inefficient for several industries. All these factors limit an extended use of ultrasound, especially in industries dealing with novel, fragile, or miniature objects and/or high throughput demands.

Hence, it is an aspect of the invention to provide an alternative method for treating an object, or other material, to ultrasonic cavitation, which preferably further at least partly obviates one or more of above-described drawbacks, and which method may especially enhance or improve ultrasonic treatment. It is a further aspect of the invention to provide a layer of a material, which layer may e.g. be used to conformally enclose an object, or to create an enclosure (for enclosing such object), which layer (or enclosure) further at least partly obviates one or more of above-described drawbacks, and which layer (or enclosure) may especially enhance or improve ultrasonic treatment.

The invention provides a method that has been shown capable of controlling the microbubbles (herein also indicated to as "bubbles") in space and time, i.e. the location and activity of the microbubbles are well defined. This control allows for a much higher cleaning/treatment efficiency of ultrasonic processes. Control over the microbubbles is achieved by creating artificial crevices or cavities (such as e.g. having diameters typically in the range of 10-2000 μπι) on the surface of a substrate, in which air (or another gaseous material) is entrapped. When the substrate is vibrated ultrasonically by subjecting a liquid comprising the substrate to ultrasound, cavitation bubbles are generated from the air pockets entrapped by the crevices. Especially, the present invention provides a method for enhancing cavitation effects by influencing not only the acoustic amplitude, but also the bubble population. Moreover, the (micro)bubbles generated may essentially be controlled regarding their size and location by the method and products as described herein. To this end, the cavities are provided. The cavities are herein also indicated as "micropits" or "crevices"

Hence, in a first aspect the invention provides a method for treating an object (or other material), such as with ultrasonic cavitation, the method comprising (a) providing a liquid, (b) arranging the object in the liquid (or providing material to an enclosure), wherein the object (or other material) is (thus) especially enclosed in an enclosure, wherein the enclosure comprises an enclosure material having a material surface directed to the object (or the other material), the material surface comprising cavities, especially having equivalent circular diameters selected from the range of about 10 μιη - 2 mm, and (c) providing ultrasound to the liquid (thereby especially generating cavitation bubbles in the liquid). Especially, by configuring the material surface (comprising the cavities) to the object (or other material), the bubbles generated may effectively be directed towards the object (or other material) to be treated e.g. for surface treatment of the object, such as for cleaning of an object.

Especially an object may be treated with the herein described method.

However, the cavitation bubbles may further effectively be used for process intensification, such as in chemical processing or food processing. The process intensification, for instance, may be used in emulsification processes, such as in the preparation of an (oil-water or water- oil) emulsion, like in the preparation of mayonnaise wherein the liquid materials may be emulsified. The method further may be effectively used for synthesis of nano -materials. Hence, amongst others, the invention provides micropits for cleaning an object, or for other purposes.

Hence, in an embodiment the invention provides a method for treating an object, the method comprising: (a) providing a liquid; (b) arranging the object in the liquid, wherein the object is at least partially enclosed in an enclosure, wherein the enclosure comprises (polymeric) enclosure material having a (polymeric) material surface directed to the object, the (polymeric) enclosure material surface comprising cavities, especially having equivalent circular diameters selected from the range of 10 μιη - 2 mm; and (c) providing ultrasound to the liquid. In yet a further embodiment, the invention provides a method for treating liquid material, the method comprising: (a) providing a liquid; (b) arranging the liquid material in an enclosure in the liquid, wherein the enclosure comprises (polymeric) enclosure material having a (polymeric) material surface directed to the liquid material, the (polymeric) material surface comprising cavities, especially having equivalent circular diameters selected from the range of 10 μιη - 2 mm; and (c) providing ultrasound to the liquid.

It has been shown that especially with the present method surface treatment, such as cleaning, may be more efficient than with prior art methods. Further, with a relative cheap method in a reliable way objects can be cleaned, such as medical tools, contact lenses, jewelry, a fastener (such as a screw, a nut, a bolt, etc.), etc.. These may for instance be provided packaged in the enclosure, and may thus be treated with the present method before use, in e.g. a hospital.

The use of the term "enclosure" does not imply that the object (or other material) is necessarily entirely enclosed. Hence, herein it is also indicated that the object may at least partly be enclosed. Further, the enclosure may include a main opening, which may not necessarily be closed. Of course, in embodiments, the enclosure may be closed (during execution of the herein described method).

Further, the enclosure may include a liquid tight enclosure with cavities that are not configured as through cavities. In yet other embodiments, the enclosure may be substantially closed (optionally except for a main opening), but with through holes (i.e. cavities configured as through holes). In such embodiment, the enclosure may not be entirely water tight, but for instance in some embodiments it may still be possible to entrap gas in these through holes that can be used for generating cavitation, depending upon the dimensions of the cavities, the ultrasound frequency and the time needed to subject the object (or other material) to the bubbles.

In a further embodiment, the enclosure (first enclosure) comprising through holes may be enclosed by a second enclosure, wherein gas is provided to a space between the first and second enclosure, and wherein especially the gas may enter the first enclosure via the through holes. Hence, in an embodiment the object is at least partially enclosed by a first enclosure, wherein the first enclosure comprises (polymeric) enclosure material having a (polymeric) material surface directed to the object, the (polymeric) material surface comprising cavities having equivalent circular diameters selected from the range of 10 μιη - 2 mm, wherein the first enclosure comprises through hole cavities, wherein the first enclosure is partially enclosed by a second enclosure, wherein the method further comprises providing a gas to a space between the first enclosure and the second enclosure. Especially, during application of the ultrasound part of the second enclosure is in contact with a second liquid. In yet a further embodiment, the second enclosure is configured to only partially enclose the first enclosure, and wherein during application of the ultrasound part of the first enclosure and part of the second enclosure is in contact with the second liquid. Such embodiment may allow a good penetration of the ultrasound as well as an enhanced generation of bubbles. In yet a further specific embodiment, the second enclosure and the first enclosure are configured to provide an envelope, with the envelope having an opening for introduction of the gas, and with the through cavities in the first enclosure as outlets. Optionally, a plurality of openings may be applied. During execution of the method, a gas pressure at least higher than ambient pressure is provided to the envelope by introduction of gas through the opening. The first and second enclosure are configured to provide a space or envelope.

In yet other embodiments, the enclosure may include a mesh enclosure. Such enclosure is not a liquid tight enclosure. The meshes are substantially larger than the cavities.

Further, the enclosure may comprise a rigid or non-rigid (flexible) enclosure material.

A liquid tight enclosure especially may be used to subject one or more liquids to ultrasound. However, a liquid tight enclosure may also be used to treat a subject a (solid) object (by applying ultrasound to the liquid in the enclosure and/or surrounding the enclosure).

Hence, the object treated thus refers to an object substantially consisting of solid material, which is visible or tangible and is relatively stable in form, though it might be flexible. In those embodiments, the enclosure may be closed or may include through openings, including meshes. In other embodiments, liquid material may be treated. In such instance, the enclosure will in general be closed, to contain the liquid. Nevertheless, in these embodiments the enclosure may e.g. include a main opening (during treatment), which is arranged over the liquid(s). The term "treatment" and "treating" and similar terms may refer to substantially any action, but especially including cleaning, starting and/or enhancing a reaction, starting and/or enhancing emulsification, mixing or enhancing mixing, etc..

These embodiments are further elucidated below.

The enclosure material especially comprises a solid enclosure material. Further, this enclosure material (i.e. the material substantially constituting the enclosure) may be a rigid enclosure material, such as a metal, a rigid polymer, or a glass. The enclosure material may also comprise a flexible enclosure material, such as a flexible polymer. Especially, the enclosure is flexible, wherein the flexibility may stem from the (physical) enclosure material properties as well as the dimensions (such as the thickness of a layer or mesh structure) of the enclosure material comprised in the enclosure. For example the enclosure material may comprise a flexible polymer such as a (thin) flexible plastic or a (artificial) rubber. However, the enclosure material may also comprise a rigid enclosure material, for instance if the enclosure comprises a net or a wire gauze, such as a wire gauze comprising thin metal wires or polymer wires. However, the wire gauze may (thus) also comprise a flexible material, such as flexible polymeric material. The enclosure material may comprise a plastic or any other material. Especially, however, the enclosure material may be selected allowing transmission of ultrasound (larger than 0%). This may especially be of relevance when the enclosure is configured to substantially completely enclose an object. In a specific embodiment, the enclosure material especially is a polymeric material, such as a plastic or a (synthetic) rubber. Especially, the polymeric material may be selected from the group consisting of ABS (acrylonitrile butadiene styrene), Nylon (or polyamide), Acetate (or cellulose), PLA (poly lactic acid), terephthalate (such as PET polyethylene terephthalate), EPDM, Polypropylene (PP) (or polypropene), Polystyrene (PS), PE (such as expanded- high impact-Polythene (or polyethene), Silicone rubber, Low density (LDPE) or High density (HDPE) polyethylene, PVC (polyvinyl chloride), Polychloroethene, natural rubber, styrene- butadiene rubber (SBR), etc. In an embodiment, the enclosure material of the method described herein, comprises a polymeric enclosure material, wherein the polymeric enclosure material comprises a flexible polymeric enclosure material. In a specific embodiment, the flexible polymeric enclosure material comprises one or more of polypropylene (PP) and polyethylene (PE).

A flexible enclosure is especially advantageous because it may enclose the object to be treated substantially conformally to enhance an effective treatment of the body enclosed. Especially, the cavities may be arranged such that the shortest distance between a cavity and the object (to be treated) is preferably less than 1 cm, to enhance the treatment of the object (see also below). Furthermore, when using an enclosure substantially conformally enveloping an object to be treated, it may be advantageous to select a pattern of cavities (like local cavity density, local size of the cavities, local shape of the cavity, etc.) that may enhance a local required treatment of the object. It further may e.g. be advantageous to configure a shape of an enclosure especially based on a shape of the object to be treated.

Hence, in an embodiment, the method further comprises generating the enclosure in dependence of the object to be treated, such as in dependence of the size of the object, the shape of the object, the locally required bubbles, etc.. Especially configuring the shape of the enclosure to allow enclosing the object substantially conformal may be advantageous. Hence, in an embodiment the method may further comprise generating a shape of the enclosure in dependence of a shape of the object to be treated. In a further embodiment, the method comprises providing the cavities in dependence of the object to be treated. It may especially be advantageous applying a method comprising generating a shape of the enclosure in dependence of the shape of the object and further providing the position of the cavities in dependence of the shape of the object. By configuring the pattern of cavities to the shape of the body, the treatment may be performed more efficiently and focused. Moreover, especially a specific location on the body may be treated more severely (such as when the treatment is a cleaning treatment, the location of dirty spots and stains), or less severely, or may substantially not be treated (especially e.g. a location being more fragile and/or more susceptible to ultrasound).

The motion of cavitation bubbles towards an object may be a result of the effect of the so called secondary Bjerknes forces, which may make bubbles close to an object "feel" the presence of their image bubble on the other side of the object surface as an attraction force, driving the bubbles closer to the object. Especially, a bubble that is less than 1 cm apart from the surface of an object may be attracted to the object and may effectively bring about the intended effect (as a result of the ultrasonic cavitation). Hence, it may be advantageous to generate the enclosure in dependence of the shape of the object to be treated, and preferably especially arranging the cavities of the enclosure within a range of 0 - 1 cm apart from the object. Hence, it may be especially advantageous if shortest the distance between the enclosure and the object is substantially less than 1cm (at a location of the object to be treated). Further, it may be advantageous that at least part of the object is at a non-zero distance from the enclosure, such as at least 10 μιη, such as at least 20 μιη, i.e. with liquid between the object and the enclosure.

The enclosure, further, may comprise elements to keep the (plastic) enclosure submerged and in place, such as gas pockets to ensure floatation and/or ballasting pieces of solids.

In another aspect, the invention provides a layer of (polymeric) material having a (polymeric) surface comprising cavities, especially having equivalent circular diameters selected from the range of about 10 μιη - 2 mm, and especially having depths of at least 5 μιη. The layer of material may especially be of polymeric material. However, the layer of material may also comprise another material, especially the material comprises a flexible material (see also above). The layer may especially be used to wrap around - or to provide adjacent to - an object to be treated. The layer may further be used to provide a (flexible) enclosure, especially an enclosure comprising the layer to contain a solid and/ or a liquid, such as an object or a mixture of liquid(s) and /or solid(s). Hence, the enclosure may comprise one or more layers configured as enclosure, such as e.g. polymeric sheets melted together at one or more edges to provide a bag. Especially, the enclosure may (at a later stage) be used to subject the solid or liquid contained in the enclosure to ultrasound. The layer may be used for different applications and in different methods. The layer, and especially an enclosure comprising the layer, may especially be applied in the method of the present invention. Vice versa, the method as described herein, may especially comprise an enclosure comprising the layer according to the invention. The layer may have a thickness in the range of about 5 μιη - 5 mm, especially in the range of 5 μιη - 2 mm, such as in de range of 5 μιη - 0.5 mm, or in the range of 0.5 mm - 2 mm. Especially, a layer comprising a polymeric material may have a thickness ranging from 5 μιη - 0.5 mm. In an embodiment, the layer has a thickness of at least 10 μιη, such as at least 100 μιη. The layer may comprise polymeric material, such as flexible polymeric material, a metal, such as stainless steel, or a glass. Especially the layer comprises a flexible material. Hence, the enclosure may especially comprise a flexible bag (with a (single) main opening).

The layer may further comprise a closed (water tight) layer or a layer with openings (such as a mesh). The layer may in an embodiment be closed, with indentations (as cavities); i.e. no through holes. Hence, in an embodiment the layer is a closed layer. In this embodiment, the layer is thus water tight.

Furthermore, in an embodiment the closed layer may be water tight while comprising cavities or perforations through the layer (through holes).

In yet another embodiment, the layer may comprise an open layer comprising openings that are especially (substantially) larger that the size of the cavities. Hence, in an embodiment, the layer comprises a mesh, especially a polymeric mesh, wherein the (polymeric) mesh comprises the material, especially the (polymeric) material comprising mesh openings.

The layer may comprise a rigid layer or a flexible layer (see also above).

Especially, the layer may comprise a flexible layer, allowing to wrap around an object or to be comprised in a flexible enclosure. Especially a flexible enclosure, wherein the flexible enclosure especially may be used in the method described herein. It may especially be advantageous if the layer comprises a flexible material, especially a flexible polymeric material. Hence, in a specific embodiment, the invention provides a layer of polymeric material, wherein the polymeric material comprises a flexible polymeric material, especially comprising the layer of a polymeric material having a polymeric material surface comprising cavities having equivalent circular diameters especially selected from the range of 10 μιη - 2 mm, and having depths of especially at least 5 μιη.

Hence, in a specific embodiment the layer is a closed layer, especially a closed polymeric layer. In a further embodiment, the layer comprises a mesh, especially a polymeric mesh. In this latter embodiment, the layer especially comprises the polymeric material comprising the mesh openings.

Especially, the layer may be used to provide an enclosure, especially a flexible enclosure to contain a material, such as a liquid material or solid material. In a specific embodiment, the enclosure is designed to enclose an object (as embodiment of solid material). Hence, especially for such a kind of object the enclosure may comprise a (flexible) enclosure, such as a (flexible) polymeric bag, and may especially be used in the method described herein.

However, the enclosure may also be applied in an alternative method. The enclosure may for instance also be used for performing a physical or chemical process with the material(s) contained, wherein the process may be induced or enhanced by and/or intensified by providing ultrasonic cavitation to the material(s) contained. For example, emulsification of at least two liquids may be provided by providing the liquids into the enclosure and subjecting the enclosure to ultrasound. Additionally, a physical mixer may be used, wherein the ultrasound intensifies the mixing process. Especially an enclosure comprising the layer provided herein may be used for the method. Hence, the method described herein may comprise a solid material, such as an object, and alternatively or additionally other material, such as a liquid. Hence, the object described herein may in some embodiments also be replaced by another material such as a liquid or a solid, especially a liquid. Hence, instead of an "object" also a "liquid material" or "solid material" may be applied in the herein described method.

Moreover, in yet a further aspect, the invention provides an enclosure comprising the layer described herein, comprising an opening for introduction of a solid (such as especially an object) or liquid material. The enclosure may comprise at least one layer as described herein. The enclosure, for instance may comprise exactly one layer according to the present invention, wherein the layer is arranged to provide an enclosure, or the layer may be combined with another layer not comprising cavities, to provide an enclosure. The enclosure may also comprise two (or more) layers according to the present invention wherein the two or more layers are configured to provide an enclosure. For instance two layers with a different pattern of cavities, or one flexible layer and one rigid layer, or even another combination of two (or more) layers according to the present invention may be assembled to provide the enclosure.

The layers may especially be configured in dependence of the object to be treated. In an embodiment, one layer may be provided over another layer, wherein more than one layer may enclose a material comprised in the enclosure (when in use). In addition, other configurations are possible to configure an enclosure comprising at least one layer according to the invention. In a specific embodiment, the invention further provides an enclosure (comprising a layer) as described herein comprising trough holes, wherein the enclosure is at least partially enclosed by a second enclosing element comprising a gas. The second enclosing element may especially be connected to the enclosure by a gas tight seal disabling a flow of gas via the connection. Especially, in such an embodiment extra gas may be introduced in the enclosure via the through holes. In a further embodiment, the second enclosure may further comprise an opening to provide a flow of gas in the second enclosure. Especially by providing a gas to the second enclosure an enhanced flow of gas through the through hole into the enclosure may be provided. It further appears to be advantageous if the enclosure is provided with an (extra) opening allowing gas to leave the enclosure, especially a second opening configured to control the flow of gas leaving the enclosure.

In an embodiment, the invention provides a method, comprising providing a bath with the liquid, wherein the enclosure comprises a mesh wherein the mesh comprises the material, especially the object, comprising mesh openings and threads comprising the cavities. An enclosure comprising a mesh especially may not be a liquid tight enclosure. Moreover, the mesh openings especially are substantially larger than the cavities. An object may be placed in the mesh and arranged in a bath comprising a liquid. Especially a flexible mesh may enclose the object to be treated substantially conformally to enhance an effective treatment of the body enclosed. It further may be advantageous to configure multiple objects in the mesh. Additionally one or more extra meshes may be configured around the body to further enhance the potential generation of bubbles. A mesh may further be advantageous, since the ultrasound transparency of such enclosure may be larger. Hence, the ultrasound transparency of the thread material may be relatively low, since the ultrasound can progress through the mesh openings. For instance, metal threads may be applied. The mesh may either be a rigid mesh or a flexible mesh. However, the mesh especially is a flexible mesh allowing the mesh (or the enclosure comprising the mesh) substantially to match the shape of the object enclosed. Hence, especially, a mesh (also indicated herein as "wire gauze") comprising a rigid enclosure material may comprise threads (or wires) having a smaller diameter (or other essential lengths determining the flexibility) than a mesh comprising a flexible enclosure material. Especially a characteristic smallest size (such as a diameter or a width or a thickness) for a rigid enclosure material, such as metal, may be selected in the range of 0.1 mm - 10 mm, such as 0.1 mm - 1.5 mm, or especially 0.2 - 1 mm, and a characteristic smallest size of a flexible enclosure material, such as a polymer, may be selected in the range of 0.1 - 10 mm, such as 0.1 - 5 mm, especially 0.5 - 2 mm. The treads may be configured as wires but may also be configured as layers (such as strips), having a non-circular cross-section, such as a substantially square or substantially rectangular cross-section.

Especially, the equivalent circular diameter of the mesh opening may be selected from the range of about 0.5 mm - 30 mm, especially 1 mm - 15 mm, and even more especially 1 mm - 5 mm. However, mesh openings may also be larger.

In a specific embodiment, the enclosure comprises a polymeric mesh, wherein the polymeric mesh comprises the polymeric enclosure material.

In a further embodiment, a layer comprises a mesh, wherein the mesh comprises crevices or cavities at its nodes. The mesh, especially comprises a flexible mesh and for example can be imagined as a mandarin net. Such mesh may for instance be used to suspend an object to be cleaned at a given distance from the bottom of an ultrasonic bath, in order to prevent the object from affecting the ultrasound generation and damage of the bath's inner surface. In the prior art, rigid baskets are used inside an ultrasonic bath and these baskets are typically made out of metal. It appears that such baskets significantly affect the ultrasound field. Embedding artificial cavities in the basket surfaces may already promote the generation of cavitation for cleaning. However, placing an object to be cleaned in a mesh, or wrapping a mesh around the object may be more advantageous. The mesh may comprise a rigid solid enclosure material such as metal, or a flexible solid enclosure material that allows for wrapping around the object to be cleaned. Especially the mesh comprises a flexible enclosure material.

A characteristic depth of a cavity is selected in the range from 5 μιη - 500 μιη, especially 5 μιη - 100 μιη. However, cavities comprising a larger depth are also possible. Moreover, the cavity depth may be as large as the thickness of the enclosure wherein the cavity essentially comprises an opening (through the enclosure) or perforation. Hence, the invention provides in an embodiment a material surface (of especially an enclosure), wherein the cavities have a depth of at least 5 μιη. Hence, the cavities may in an embodiment be through holes or perforations. In yet another embodiment the cavities comprise indentations (i.e. no through holes).

The cavities may be selected in size and shape (but also e.g. in number of cavities per cm², depth of the cavity, etc.). For instance, in an embodiment, all cavities are circular cavities (i.e. cavities having circular cross-sections) with substantially equal (circular) diameters. In another embodiment, all cavities are circular and the (circular) diameter of the cavities is selected from the range of 10 μιη - 2 mm. In yet another embodiment, cavities comprising a circular shape (cross-section) as well as cavities comprising an elongated shape (cross-section) and cavities comprising a triangle (cross- section) and cavities comprising a square shape (cross-section) are provided. In yet another embodiment at least two differently shaped (cross-sections) cavities or cavities comprising at least two different dimensions are provided. Especially, all cavities having an equivalent circular diameter selected in the range of 10 μιη - 2 mm.

Herein the equivalent circular diameter of a random shaped cavity is defined by 2*V( cross-sectional area of the cavity/π) (being equal to the diameter of a circular shape with the same area). The size of the most advantageous equivalent circular diameter may depend on the frequency of the ultrasound waves generated. Especially, the applied equivalent circular diameter may be selected smaller at a higher ultrasound frequency (to be applied) and the selected equivalent circular diameter may be selected larger at a lower ultrasound frequency (to be applied). The cavities may especially have equivalent circular diameters selected from the range of 10 μιη - 2 mm, even more especially in the range of 10 - 500 μιη, such as 10 - 100 μιη. The cavities may especially have a circular cross-section. However, alternatively the cavities may have a square, rectangular, triangular, or other cross- section. Especially however, in an embodiment the shapes (cross-sections) of the cross- sections are substantially identical over the material surface. Further, the cavity density may especially be in the range of 0.1 - 1000 cm^"2, such as 1 - 1000 cm^"2 (i.e. 1 - 1000 micropits per square centimeter).

The enclosure or layer described herein may be generated in dependence of the type of enclosure and/or the (enclosure) material. An enclosure comprising a metal mesh, for instance may be configured from a metal thread comprising cavities provided by a laser. Arranging the threads may comprise weaving the thread(s) to provide the mesh, but also alternative ways to arrange are possible. A metal or a polymer mesh also may be configured from a commercial metal or polymer type wire gauze provided with cavities (in the threads). A water (or liquid) tight enclosure may for instance be configured from a water (or liquid) tight layer, wherein cavities are provided.

For instance cavities may be provided by a laser to obtain the desired shape, depth, and size. Alternatively, especially small cavities may be provided by a dry plasma etching technique. Furthermore, it appears to be an advantageous method to provide cavities in a layer, especially a polymer layer by a squeezing the layer in a mold comprising protrusions (such as small spikes) of the size and shape of the required cavities, and successively arranging the layer into an enclosure. The mold may be configured by precision tooling, however, the mold also may be provided by 3D-printing (allowing to design the cavity pattern). Especially by providing a (tailor made) mold, a tailor made enclosure (for an object or another material to enclose) may be provided that substantially conformally may enclose the object (or other material). The depth and shape of the cavities may especially be configured by the shape and the size of the protrusions. The depth, however, may further be configured by the pressure of squeezing the mold. Large (long) protrusions and or large pressures may especially be applied to provide trough holes or perforations (cavities having a depth larger than the thickness of the layer). Hence, the invention also provides an embodiment wherein the method further comprises providing a mold comprising protrusions for generating at least part of the enclosure by contacting an enclosure (base) material, such as a polymeric material, with the mold to provide the cavities in the enclosure material, such as the polymeric enclosure material.

Further, also a combination of different cavities may be applied. Further, the cavity depth and/or cavity shape may differ over the material surface (of the enclosure). Further, the cavity dimensions may be selected in dependence upon the frequency of the ultrasound; or vice versa, the frequency of the ultrasound may be selected in dependence of the cavity dimension (see also below).

The bath may be a bath (or liquid container) comprising the liquid, wherein successively bubbles may be generated by ultrasound provided by an ultrasonic horn. However, it may especially be advantageous if the bath comprises an ultrasonic bath comprising an ultrasound wave generator. Also combinations may be applied.

An enclosure comprising a mesh advantageously may be applied in a bath comprising the liquid. In an embodiment of the invention, a method is provided comprising enclosing an object to be treated (to treat or to support treating) in the enclosure comprising a mesh, successively arranging the object (in the enclosure) in the bath comprising a liquid, and finally subjecting the object to bubbles generated in the liquid (at the (enclosure (especially the thread) comprised) material) by ultrasound. Of course, the enclosure may also be first arranged in the liquid, followed by arranging the object in the enclosure.

The ultrasound may especially be generated by for instance an ultrasound wave generator comprised in the bath and/or by an ultrasonic horn (manually) provided in the liquid. Especially, for treating multiple objects at the same time, it may be advantageous to apply the method in a bath. It furthermore may be advantageous to apply the mesh described herein. However, for treating a single object, it may be advantageous to directly provide the ultrasound (in the liquid) in an enclosure that does not comprise mesh openings, especially an enclosure that may contain the liquid without requiring a complete bath (filled with the liquid). This may especially be advantageous if the treatment requires a specific liquid, such as a cleaning liquid such as water, pure or diluted solutions of acetone, ethanol, or strongly alkaline or acidic solutions (or solvents). Hence, the invention also provides a method wherein the enclosure is configured to contain the liquid, wherein the method especially further comprises arranging an ultrasonic horn in the liquid in the enclosure, and subjecting the object to ultrasound.

However, as also indicated above, it may also be advantageous using a closed (liquid tight) enclosure and subjecting the object in the closed liquid containing enclosure to ultrasound generated in an ultrasound bath. Especially for subjecting multiple objects to ultrasonic cavitation, it may be advantageous to use a bath, such as a standard ultrasonic (cleaning) bath, and to enclose the objects individually (in the enclosure(s), wherein the enclosure(s) may be used to substantially match the shape of the object).

Hence, in an embodiment, the invention further provides a method comprising arranging the enclosure in a bath comprising a second liquid and subjecting the object to ultrasound by providing ultrasound to the second liquid. Further, the ultrasound radiation may be directed to the second liquid (like in the case of an ultrasonic bath), but alternatively or additionally the ultrasound radiation may be directed directly in the first liquid in the enclosure (such as when including an ultrasonic horn in the first liquid), when the enclosure is a liquid tight enclosure. It may further be advantageous, especially if the enclosure is liquid tight, to select a first liquid that differs from the second. The first liquid for instance may comprise a cleaning agent whereas the second liquid may comprise water. However, the first liquid and the second liquid may also be selected to be equal. The first liquid and the second liquid for instance both may comprise water. Hence, in embodiments wherein a liquid tight enclosure is applied, the liquid within the enclosure may differ from the second liquid in the bath. As indicated above, e.g. the liquid in the enclosure may include a cleaning liquid. Or the treatment is used to treat the liquid for other purposes.

The effects induced by (acoustic cavitation) bubbles is especially determined by the response to the effects of a collapsing bubble, the location of the bubble and the number of bubbles. It was found that these parameters essentially may be controlled by the acoustic waves and by the size and location of the cavities that induce the bubble formation. However, also a bubble may react differently towards different acoustic waves. Hence the selected acoustic wave generator settings (such as frequency, amplitude, waveform, etc.) may correlate with a desired cavity pattern (such as size of the cavity, location of the cavity, cavity density etc.). Additionally, due to effects such as acoustic shielding and bubble-bubble interactions extra correlations may be present. Next to that, there may be a frequency dependent lower acoustic power threshold for cavitation activity, also referred to as the nucleation threshold, and e.g. the selected acoustic wave frequency may affect a possible temperature rise. Hence it is especially advantageous for treating a broad range of objects to apply different settings to the acoustic wave generator and/or select the dimensions of the cavities. The optimal size of the cavities for cavitation enhancement may depend on the ultrasound frequency, with smaller cavities requiring higher frequencies in order to be excited properly. An estimate of the frequency/cavity size relation can be made from the resonance frequency approximation for a free gas bubble in water (Minnaert theory): radius (mm) X frequency (kHz) = 3.3. This number is different for each liquid, dissolved gas and ultrasound pressure. For typical ultrasonic frequencies used in the industry (20 - 200 kHz), the pore size will be in the micrometer to millimeter range. As an example for a surface comprising cavities in water, the cavity size may be around 100 μιη at a frequency of 33 kHz. Hence in an embodiment of the invention comprises a method, wherein the ultrasound has a frequency in the range of 20 kHz - 1 MHz, and wherein the equivalent circular diameters are selected from the range of d=(3.3*c)/(2*f), wherein d is the equivalent circular diameter (mm), f is the frequency (kHz) and c is a constant selected from the range of 0.2 - 5. Also a range of c values may be chosen (and thus a range of diameters)). In this way, one may take into account the use of different environmental conditions such as different liquids, gases, and pressures. By default, c may be chosen as 1.

Even more especially, in an embodiment the invention provides a method, wherein the ultrasound has a frequency in the range of 20 kHz - 1 MHz, and wherein the equivalent circular diameters are selected from the range of: , 1/2

D = 2*(c/(2*7I*f/))*((3*Y *Patm)/p) wherein D is the equivalent circular diameter (m), f is the frequency (Hz) and c is a constant selected from the range of 0.2 - 5, γ is the polytropic coefficient of the gas inside the bubble, Pat_m is the ambient pressure (Pa), and p is the fluid density (kg/m³). By default, c may be chosen as 1.

In a further aspect, the invention provides the use of an enclosure as provided herein, especially wherein the enclosure comprises one or more layers constituting the enclosure, wherein the enclosure is especially used to contain a (solid or liquid) material, for treating the solid or liquid material to ultrasound, such as with the method as described herein.

The layer or enclosure may also be used for process intensification (i.e. a treatment comprising process intensification). The layer or enclosure especially may be used to intensify a chemical or physical process by focusing and enhancing the effect of ultrasound at a specific location (in the enclosure). Mixing, for instance, may be intensified by bubbles that may (locally) be generated from the cavities by ultrasound inside the enclosure.

The enclosure or layer may also be used for surface modification (of an object), especially while using the herein described method. Surface modification of an object may e.g. include a surface reaction (with the liquid) of the surface of the object.

Alternatively or additionally, the layer or enclosure may be used for cleaning of the object, especially while using the herein described method. It appears to be advantageous to apply the method described herein for cleaning a medical tool. Additionally or optionally the enclosure described herein may be used to clean the medical tool.

Hence, the object may comprise a medical tool, or a contact lens, or an additive manufactured object (a 3D printed object), or a jewelry item, or historical artifacts, or car components, or screws, or ferrules, or transport belt pockets, or semiconductor wafers, or research lab-ware, etc. etc..

Alternatively or additionally, the enclosure may be used for process intensification, such as enhanced mixing or emulsification, with the enclosure enclosing a liquid material and optionally a solid material. Alternatively or additionally, the enclosure may be used for a synthesis of nanomaterial.

In yet a further embodiment, the invention provides a particle comprising small openings holes or pores on the outer surface, with a specific size, whereby the pores act as the above-mentioned artificial crevices or cavities. Upon submerging these particles in a liquid, air is entrapped in the pores. The air pockets may act as sources of cavitation nuclei, which, under the influence of ultrasound, may enhance cleaning or other surface modifications on a nearby surface. These 'cleaning-enhancing' particles or 'mobile micropits' may increase the number of cavitation nuclei present in a liquid, especially allowing a much lower cavitation threshold than the usual energy value (electric power) to form cavitation. These particles therefore do not clean in a direct way (i.e. abrasion), but rather may enhance cleaning in an indirect way, by facilitating cavitation effects known to cause cleaning, such as Shockwaves, liquid jets, shear stresses, etc.

Applying these cleaning-enhancing particles advantageously may allow enhanced cleaning of surfaces and inside hollow spaces that are difficult to access. The particles, especially may enhance the cavitation occurrence without needing surfactants or other chemicals. This enhancement reduces the treatment time required, thereby speeding up the cleaning process and reducing the amount of power. In production processes, both effects can have an overall positive impact in revenues. Cavities of a single size or with a specific size distribution pattern may be provided artificially into a material. Additionally or alternatively, a porous material with a specific pore size distribution may be fabricated. Cavity sizes of the cleaning-enhancing particles may be configured based on a specific ultrasonic frequency in a given application. Artificial cavities may allow for further control over the cavitation enhancement process. The size of the particles may be selected to allow a particle to enter the small places to be cleaned in a specific application. However, they especially also must be large enough to comprise one or more pores. Hence the particles are especially selected comprising a particle sizes ranging from 100 μιη to a few mm in diameter. The shape of the particles may be less relevant, although sharp, protruding edges may be avoided to prevent damage to the surfaces to be cleaned. Air entrapment in the cavities may further be stimulated by hydrophobization of the cavity walls. A hydrophobic coating may be provided to the external and internal surface of the particle, or a naturally hydrophobic porous material may be selected.

In an embodiment, the cleaning-enhancing particles may be provided to the liquid contained in an ultrasonic bath, and to the inside of e.g. a hollow instrument to enhance cavitation in its interior. In another embodiment, the method comprises an ultrasonic horn or the like to generate ultrasound at a specific place (nearby the particles). In order to perform cleaning or surface modifications, the particles may need to be close to that surface. Hence, an embodiment comprises stirring the liquid containing the particles. Neutrally buoyant particles may be preferred in this situation, which can be achieved by selecting/creating a material with certain porosity and density. The aggregation of these particles further may be avoided, by providing a surfactant to the liquid. Especially providing a surfactant to the liquid may prevent particles from clustering which may (negatively) affect their working.

After the cleaning process, the particles may have to be removed from the objects that have been cleaned and from the liquid. Several ways can be envisaged to achieve this in an effective way, depending on the application: making them float, sink or dissolve. Dissolution, especially may be provide by providing specific (operating) conditions, such as a temperature change, a pH changes or a long exposure time to water, chemicals, ultrasound or other conditions.

The invention provided herein may be used in several processes such as micro-fabrication technology for wafer cleaning, photolithographic applications, for emulsification or atomization processes, water treatment, food industry, biological applications, oral healthcare, etc. The invention, especially may be used in any application that involves ultrasound and bubbles.

With the present invention the volumes of cleaning liquids/solutions needed and energy provided to the system may be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

Fig. 1 schematically depicts the method according to the present invention using an enclosure as described herein;

Figs. 2, 3a-3b schematically depict some embodiments of the method and/or the enclosure of the invention.

Figs. 4a-4b schematically depict some elements of the enclosure; Fig. 5 schematically depicts a possible way to configure a layer and enclosure; Fig. 6 schematically depicts another embodiment according to the invention; Figs. 7a- 7b schematically depict some further aspects of the invention.

The schematic drawings are not necessarily on scale.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1 schematically depicts an object 100 subjected to bubbles, for instance for a surface treatment of the object 100, such as for cleaning the object. The object 100 is at least partially enclosed in an enclosure 300, in a liquid 210 (within said enclosure). The enclosure comprises cavities 330 in its material surface 320 that are directed towards the object 100. The cavities may induce bubbles 400 under the influence of ultrasound 600. The cavities may have a random shape, or a regular shape, such as a circular, triangle, or square shape, etc. with equivalent circular diameters in the range of 10 μιη - 2 mm. In the embodiment given in figure 1, the enclosure 300 comprises a polymeric enclosure material 310 (comprising a layer 1300). Here, the enclosure 300 may essentially consist of two layers 1300, which together constitute a bag. The enclosure 300 with the (first) liquid 210 is provided in a bath 200 comprising the second liquid 220. Here, the enclosure is a closed (water or liquid tight, however may be open at one side (here main opening 301)) enclosure wherein the object 100 or any other material 1000 (for instance one or more liquids) to be treated by ultrasound is placed. The bath comprises a liquid 220 wherein the ultrasound waves 600 are generated, that successively travel to the first liquid 210 inside the enclosure. The bubbles 400 are successively evolving at the cavities 330 by means of the ultrasound waves 600 generated by an ultrasound generator. The figure also shows that (clouds of) bubbles interact with each other. This interaction amongst others may be affected by the design of the cavity and cavity pattern and the presence of the object 100. Fig. 1 also schematically depicts an embodiment of the enclosure 300 of the invention, configured as a bag of which the sides have been modified to include the cavities 330. It appeared that cavities in a polymeric material 310 act as source for cavitation bubbles 400 when placed inside an ultrasound field 600 such as present in an ultrasonic bath 650. The embodiment especially may be flexible and conformally enclosing the object, wherein the distance d_s between the object and the cavities is minimal. Preferably the distance is substantially less than 1 cm to further enhance the interaction between the cavitation bubbles and the object. During treatment, at least part of the object is thus in contact with a liquid.

An object 100 may be introduced via the opening 301 in the enclosure. Especially, a solid or liquid material 1000 may be introduced in the enclosure via the opening 301. In the embodiment the bag (or enclosure) can separate the bag contents (solid or liquid material 1000, such as the object 100) from the total bath liquid volume. For example, the user may not want to fill the entire bath with a special chemical and use a bag for using a small volume of the chemical. Alternatively, the contaminants that are cleaned off an item can be contained to the bag and may not contaminate the entire ultrasonic bath (when using a water tight enclosure 300), thereby preventing the need to clean the entire bath after every use and reducing degradation of the bath itself by contaminants. The bags with modified walls may allow for more bubbles to be generated, thereby increasing the ultrasonic cleaning efficiency for the external parts of objects 100 (e.g. coins 100). The bags can also be beneficial for emulsification and other sonochemistry uses, e.g. food processing and chemical preparations of solid or liquid material 1000.

Fig. 2 schematically depicts another embodiment of the method, wherein an ultrasonic horn 241 is used. Herein the enclosure comprises the object 100 to be treated and the horn 241 providing the ultrasound 600 generating the bubbles 400 is placed directly in the enclosure. This way, especially no bath is required to hold the enclosure. However, an ultrasonic horn may also be used in an embodiment wherein the enclosure 300 (including the first liquid 210) is placed in a bath 200 or a container or for instance a beaker comprising a second liquid 220, and wherein the horn 241 is provided in the second liquid 220.

The enclosures 300 described herein can be tuned to the application by changing the size, depth and spacing/pattern/position of the cavities 330. The size and material of the enclosure itself can be selected in order to accommodate objects 100 or other materials 100 of specific sizes and/or strong chemicals. Furthermore, adjustment of the pattern of the cavities can enhance cleaning/treatment in specific places, or omit sections from the cleaning process that don't need any cleaning (e.g. because of fragile structures).

Fig 3a schematically depicts an enclosure 300 comprising a polymeric mesh 341, wherein the polymeric mesh 341 comprises the polymeric enclosure material 310. The enclosure comprises mesh openings 342 and threads 343 comprising the cavities 330, see also fig. 4b. The enclosure especially is configured to envelop the object 100 conformally. Therefore, the enclosure especially comprises a flexible enclosure material, such as a flexible polymeric enclosure material.

Fig 3b also schematically depicts an embodiment comprising a mesh 314, especially wherein only one layer 1300 is applied. The object 100 is located adjacent to the layer 1300 and the bubbles 400 are generated at the cavities 330. The figure also schematically indicates that cavities 330 may also be configured at crossing locations of the threads 342.

Figs 4a and 4b schematically depict a section of a layer 1300 and/or an enclosure 300 comprising respectively a closed layer and mesh 341. Especially in the closed layer, the configured cavities 330 may be configured as indents 331, especially having a minimal depth of 5 μιη. However, the cavities may completely perforate the layer being configured as through holes 332 (i.e. the height or depth of the cavities is substantially identical to the thickness of the layer 1300 or enclosure (layer) 300. In embodiments both types of cavities may be provided. In Fig 4b schematically a mesh section is depicted comprising threads 343 and mesh openings 342. Cavities 330 are provided in the threads, especially with a size D smaller than the size Do of the openings or meshes. Hence, the equivalent circular diameters of the cavities are substantially smaller than the equivalent circular diameter of the meshes. Assuming that the meshes or mesh openings 342 have a substantially square cross-section with edges having lengths a, the equivalent circular diameter is 2*V(a²/7i), i.e. 2*aV(l/7i). The width of the threads 343 is indicated with reference D_m, and may e.g. be in the range of 0.1 - 100 mm, such as 0.5 - 5 mm.

Figure 5 schematically depicts an embodiment of the method wherein a mold 500 is applied to generate at least part of the enclosure 300 or layer 1300. The mold comprises protrusion 510 at a predetermined location enabling to configure a desired pattern of cavities in (or through) the surface 320 of the material when the polymeric material (being the base (enclosure) material of a layer or enclosure) is contacted with (and squeezed by) the mold.

Fig. 6 schematically depicts yet another embodiment of the method, comprising a particle 350 containing cavities 330 or pores on the outer surface, with a specific size D, whereby the pores act as the above-mentioned artificial crevices 330. Upon submerging these particles 350 in a liquid 210, air is entrapped in the pores. The air pockets can act as sources of cavitation nuclei, which, under the influence of ultrasound, enhance cleaning or other surface modifications on a nearby surface.

Fig. 7a schematically depicts an embodiment of the method wherein a material 1000 (not shown) is enclosed in a first enclosure 360. The first enclosure, may especially be an enclosure 300 as described herein. The first enclosure, may comprise a first layer 1305, which especially may comprise a layer 1300 as described herein. The first enclosure is partially enclosed by a second enclosure 370 or second layer 1310. The second layer 1310 and the second enclosure 370 especially enclose the first enclosure 360 at the locations of the through hole cavities 400 present in the first enclosure 360. The second layer 1310 (or second enclosure 370) may for instance be connected to (the first layer 1305 of) the first enclosure 360 by a gas tight seal 730. The (second layer 1310 of the) second enclosure 370 may for example be heat sealed or glued to each other. But also other techniques are known to provide a gas tight seal. Gas may be provided via an inlet 710 to the space 1400 between the first enclosure 360 and the second enclosure 370. Successively the gas may leave the space 1400 via the cavities 330, in the embodiment especially functioning as envelope gas outlet 715 in (the layer 1305 of) the first enclosure 360 to supply extra cavitation bubbles 400 (see also Fig. 7b), and to enhance the ultrasound treatment. Successively the gas may stay in the first enclosure 360, or it may leave the first enclosure 360, via e.g. an extra gas outlet 720 that may be regulated (to control the supply of gas entering the envelope 700 in the space 1400 via the gas inlet 710). The second enclosure 370, especially the second layer 1310 only partly encloses the first enclosure 360 or first layer 1305 (at the relevant places) to support the transmission of ultrasound generated in the second liquid 220 to the first liquid 210 surrounding a material 1000 like an object 100 (not shown in the figure) to be treated. Space 1400 is herein also indicated as envelope 700. Envelope 1400 is in this embodiment shaped with a kind of lobes or hollow ribs. Hence, in an embodiment the envelope 1400 comprises hollow rib elements, which only partly enclose the first enclosure 360 (or first layer 1305). The lobs may especially be configured to convey gas, but allowing liquid elsewhere. If the whole intermediate envelope is filled with gas, then the transmission of ultrasound might be less efficient.

Herein, as gas may e.g. air or Nitrogen be applied. Optionally, one or more of argon and SF₆ may be applied. Also combinations of two or more of (these) gasses may be applied.

Fig. 7b may schematically depict a cross section of the embodiment depicted in figure 7a, especially a cross-section at the line 7B-7B in Fig. 7a, wherein the second enclosure layer 1310 encloses the first layer 1305 providing the partially enclosing second enclosure 370 especially at the location of the through hole cavities 332 in the first enclosure 360. However, Fig 7b may also schematically depict a cross section of another embodiment wherein the second enclosure 370 for instance completely encloses the first enclosure 360 and providing an envelope (1400) with gas between substantially the complete first enclosure 360 and the second enclosure 370. In such an embodiment, the ultrasound especially may be generated inside the first liquid 210, for instance by a horn (not shown in the figure), so a more efficient ultrasound transfer from the generator to the first liquid 210 may be provided.

The term "substantially" herein, such as in "substantially consists", will be understood by the person skilled in the art. The term "substantially" may also include embodiments with "entirely", "completely", "all", etc. Hence, in embodiments the adjective substantially may also be removed. Where applicable, the term "substantially" may also relate to 90% or higher, such as 95% or higher, especially 99% or higher, even more especially 99.5% or higher, including 100%. The term "comprise" includes also embodiments wherein the term "comprises" means "consists of. The term "and/or" especially relates to one or more of the items mentioned before and after "and/or". For instance, a phrase "item 1 and/or item 2" and similar phrases may relate to one or more of item 1 and item 2. The term "comprising" may in an embodiment refer to "consisting of but may in another embodiment also refer to "containing at least the defined species and optionally one or more other species".

Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

The devices herein are amongst others described during operation. As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The invention further applies to a device comprising one or more of the characterizing features described in the description and/or shown in the attached drawings. The invention further pertains to a method or process comprising one or more of the characterizing features described in the description and/or shown in the attached drawings.

The various aspects discussed in this patent can be combined in order to provide additional advantages. Furthermore, some of the features can form the basis for one or more divisional applications.

Claims

CLAIMS:

1. A method for treating an object (100), the method comprising:

providing a liquid (210);

arranging the object (100) in the liquid (210), wherein the object (100) is at least partially enclosed in an enclosure (300), wherein the enclosure (300) comprises polymeric enclosure material (310) having a polymeric material surface (320) directed to the object (100), the polymeric material surface (320) comprising cavities (330) having equivalent circular diameters selected from the range of 10 μιη - 2 mm;

providing ultrasound to the liquid (210).

2. The method according to claim 1 , comprising providing a bath (200) with said liquid (210), wherein the enclosure (300) comprises a polymeric mesh (341), wherein the polymeric mesh (341) comprises said polymeric enclosure material (310), comprising mesh openings (342) and threads (343) comprising said cavities (330).

3. The method according to claim 1, wherein said enclosure (300) is configured to contain said liquid (210).

4. The method according to claim 3, comprising arranging the enclosure (300) in a bath (200) comprising a second liquid (220) and treating the object (100) by providing ultrasound to the second liquid (220).

5. The method according to any one or the preceding claims, comprising arranging an ultrasonic horn (241) in said liquid (210) in said enclosure.

6. The method according to any one of the preceding claims, wherein the polymeric enclosure material (310) comprises a flexible polymeric material.

7. The method according to any one of the preceding claims, wherein the ultrasound has a frequency in the range of 20 kHz - 1 MHz, and wherein the equivalent circular diameters are selected from the range of D=2*(c/(2*n*tf))*((3 VP_atm)/p)^1/2 wherein D is the equivalent circular diameter (m), f is the frequency (Hz), c is a constant selected from the range of 0.2-5, γ is the polytropic coefficient of the gas inside the bubble, P_atm is the ambient pressure (Pa), and p is the fluid density (kg/m³).

8. The method according to any one of the preceding claims, wherein the cavities

(330) have a depth of at least 5 μιη.

9. The method according to any one of the preceding claims, further comprising generating a shape of said enclosure (300) in dependence of a shape of the object (100) to be treated, and providing the position of the cavities (330) in dependence of the object (100) to be treated.

10. The method according to claim 9, wherein the method further comprises providing a mold (500) comprising protrusions (510) for generating at least part of said enclosure (300) by contacting polymeric enclosure material (310) with said mold (500) to provide said cavities (330) in said polymeric enclosure material (310).

11. The method according to any one of the preceding claims, wherein the object (100) is at least partially enclosed by a first enclosure (360), wherein the first enclosure (360) comprises polymeric enclosure material (310) having a polymeric material surface (320) directed to the object (100), the polymeric material surface (320) comprising cavities (330) having equivalent circular diameters selected from the range of 10 μιη - 2 mm, wherein the first enclosure (360) comprises through hole cavities (330), wherein the first enclosure (360) is partially enclosed by a second enclosure (370), wherein the method further comprises providing a gas to a space (1400) between the first enclosure (1300) and the second enclosure (370), and wherein during application of the ultrasound part of the second enclosure (370) is in contact with a second liquid (220).

12. The method according to claim 11, wherein the second enclosure (370) is configured to only partially enclose the first enclosure (360), and wherein during application of the ultrasound part of the first enclosure (360) and part of the second enclosure (370) is in contact with the second liquid (220).

13. A layer (1300) of polymeric enclosure material (310) having a polymeric material surface (320) comprising cavities (330) having equivalent circular diameters selected from the range of 10 μιη - 2 mm, and having depths of at least 5 μιη.

14. The layer (1300) according to claim 13, comprising a polymeric mesh (341), wherein the polymeric mesh (341) comprises said polymeric enclosure material (310) comprising mesh openings (342).

15. The layer (1300) according to claim 13, wherein the layer (1300) is a closed layer.

16. The layer (1300) according to any one of the preceding claims 13-15, wherein the polymeric enclosure material (310) comprises a flexible polymeric material.

17. An enclosure (300) comprising the layer (1300) according to any one of the preceding claims 13-16, comprising an opening (301) for introduction of a solid or liquid material (1000).

18. The enclosure (300) according to claim 17, wherein the enclosure comprises a first layer (1305) defining said enclosure (300) and a second layer (1310), wherein the second layer partially encloses said first layer (1305), wherein the first layer and second define an envelope (700), wherein the envelope (700) comprises an inlet (710), and wherein the envelope comprises outlets (7150), wherein the outlets comprises said cavities (330), wherein the cavities (330) are through holes in the first layer (1305).

19. Use of an enclosure (300) according to any one of claims 17-18, wherein the enclosure (300) comprises one or more layers (1300) constituting said enclosure (300), wherein the enclosure (300) is used to contain said material (1000), for treating said material (1000), wherein the material (1000) comprises a solid material or a liquid material.

20. The use according to claim 19, wherein the solid material comprises an object (100).

21. The use according to claim 20, for cleaning said object (100).

22. The use according to any one of the preceding claims 20-21, for surface modification of a surface of said object (100).

23. The use according to any one of the preceding claims 20-22, wherein the object (100) comprises a medical tool.

24. The use according to any one of the preceding claims 20-22, wherein the object (100) comprises a jewelry item.

25. The use according to any one of the preceding claims 20-22, wherein the object (100) comprises a 3D printed object.

26. The use according to any one of the preceding claims 20-22, wherein the object (100) comprises a fastener.