Dye tattoo removal

Abstract

A method of removing a dye tattoo from a region of skin comprising creating voids in the region of skin, the voids extending from a surface of the epidermis into the dermis, applying a removal compound to the region of skin, degrading the dye by the action of the removal compound, and removing the removal compound from the region of skin. A system for dye tattoo removal comprising a sensor for sensing a location of the surface of a region of tattooed skin of a subject, a dermal penetration device for creating voids in the region of skin, the voids extending from a surface of the epidermis into the dermis, a controller responsive to the sensor to control the dermal penetration device to create voids into but not through the dermis in the region of skin, and a dispenser for dispensing a removal compound to the region of skin.

Description

[0001] 1 KSF01 -134375PC

[0002] DYE TATTOO REMOVAL

[0003] This invention relates to a system and method of removing a dye tattoo.

[0004] BACKGROUND TO THE INVENTION

[0005] Tattooing is the practice of marking skin. Conventional tattooing methods use a needle, often in combination with an electric motor, to pierce the skin repeatedly. Conventional tattoo ink comprises pigments, especially inorganic pigments. Such pigments are especially challenging to remove in a tattoo removal process, often requiring many sessions of laser tattoo removal to break down the pigments sufficiently so that they can be excreted by the body. There is a need for a method of producing tattoos that may be removed more simply and effectively than conventional tattoos.

[0006] The use of dyes in tattooing has previously been unsuitable for producing permanent or long-lasting tattoos. Soluble dyes in particular are broken down in the body by natural processes such as an immune response. It would be desirable to utilise dyes as tattoo ink in such a way that lasting tattoos may be made. It is also desirable to be able to remove dye tattoos with minimal pain and in a short period of time, for example in a single session.

[0007] Conventional tattoo removal processes require a human operator to direct a laser beam at the tattoo site on a subject. Specialist training of an operator to operate a laser for tattoo removal is required. The human operator is susceptible to overlapping treated areas, which may cause excessive pain to the subject. The human operator has a limited ability to perform tattoo removal over an extended period, meaning that the total number of subjects treated in a day is limited. There is a need for a tattoo removal process that does not involve a human operator.

[0008] The methods of tattoo removal described herein are particularly effective for removing dye tattoos. The methods of tattoo removal described herein may be automated and performed without a human operator. 2 KSF01 -134375PC

[0009] SUMMARY OF INVENTION

[0010] According to a first aspect there is provided a method of removing a dye tattoo from a region of skin comprising: applying a removal compound to the region of skin; degrading the dye by the action of the removal compound; and removing the removal compound from the region of skin.

[0011] According to a further aspect there is provided a method of removing a dye tattoo from a region of skin comprising: creating voids in the region of skin, the voids extending from a surface of the epidermis into the dermis; applying a removal compound to the region of skin having the created voids; degrading the dye by the action of the removal compound; and removing the removal compound from the region of skin.

[0012] The method may comprise, prior to applying the removal compound, creating voids in the region of skin. The voids may extend from a surface of the epidermis into the dermis. The voids may not extend into the hypodermis. The voids may not extend through the dermis into the hypodermis.

[0013] Removing the removal compound may comprise washing the region of skin.

[0014] The removal compound may be applied in the form of a powder. The removal compound may be applied in the form of a liquid. The removal compound may comprise a liquid in which a powder is suspended or in which an active component has been dissolved.

[0015] The dye may be degraded by decolourisation. The dye may be degraded by removal. The removal compound may decolourise the dye, for example by causing a chemical degradation of molecules of the dye so as to reduce their colour intensity. The removal compound may cause molecules of the dye to react to one or more products which are more readily flushed from the skin than the dye.

[0016] The removal compound may comprise one or more of the following: a reducing agent, oxidizing agent, chelating agent, nucleophilic species, or complex-disrupting agents. 3 KSF01 -134375PC

[0017] The removal compound may comprise a reducing agent.

[0018] The removal compound may comprise a sodium compound. The sodium compound may be sodium dithionite, sodium bisulfite, sodium metasilicate, or a combination of two or more thereof.

[0019] The voids in the region of skin may be created by a laser. Preferably voids are created using a CO2 laser. Preferably voids are created by a pulsed laser.

[0020] Respective voids may be spaced apart by a distance of at least 50 pm, preferably 100 pm.

[0021] The step of creating voids may comprise removing a basement membrane, the basement membrane being between the epidermis and the dermis.

[0022] The method may further comprise applying an anti-pigmentation agent to the region of skin.

[0023] The dye tattoo may comprise a reactive dye molecule.

[0024] According to a second aspect there is provided a system for dye tattoo removal comprising: a sensor for sensing a location of the surface of a region of tattooed skin of a subject; a dermal penetration device for penetrating into the skin; a controller responsive to the sensor to control the dermal penetration device to penetrate into but not through the dermis in the region of skin of the subject; and a dispenser for dispensing a removal compound to the region of skin.

[0025] According to a further aspect there is provided a system for dye tattoo removal comprising: a sensor for sensing a location of the surface of a region of tattooed skin of a subject; a dermal penetration device for creating voids in the region of skin, the voids extending into the dermis; a controller responsive to the sensor to control the dermal penetration device to create voids into but not through the dermis in the region of skin; and a dispenser for dispensing a removal compound to the region of skin. 4 KSF01 -134375PC

[0026] The dermal penetration device may comprise a laser. Preferably the laser is a CO2 laser. Preferably the laser is a pulsed laser.

[0027] The controller may be configured to cause the laser to create voids in the dermis.

[0028] The controller may be configured to cause the laser to create voids in the dermis which do not extend through the dermis into the hypodermis.

[0029] The dispenser may contain a removal compound comprising a reducing agent.

[0030] The removal compound may comprise one or more of the following: a reducing agent, oxidizing agent, chelating agent, nucleophilic species, or complex-disrupting agents.

[0031] The removal compound may comprise a sodium compound.

[0032] The sodium compound may comprise sodium dithionite, sodium bisulfite, sodium metasilicate, or a combination of two or more thereof.

[0033] The system may further comprise a processor and a memory, the memory storing in non-transient form instructions executable by the processor to cause the processor to implement functions of the system.

[0034] BRIEF DESCRIPTION OF THE FIGURES

[0035] The present invention will now be described by way of example with reference to the accompanying drawings. In the drawings:

[0036] Figure 1 shows a schematic cross section of skin.

[0037] Figure 2 shows a scheme of tattoo removal.

[0038] Figure 3 shows steps of a tattoo removal process. 5 KSF01 -134375PC

[0039] Figure 4 shows an arrangement for making voids in skin.

[0040] Figure 5 shows a top-down view of a region of skin.

[0041] DETAILED DESCRIPTION

[0042] The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art.

[0043] The general principles defined herein may be applied to other embodiments and applications without departing from the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0044] There is provided a method of removing a dye tattoo from a region of skin comprising: applying a removal compound to the region of skin; degrading the dye by the action of the removal compound; and removing the removal compound from the region of skin. The tattooed region of skin may be referred to as the treated region of skin. The removal of the removal compound from the treated region of skin is at least partial removal.

[0045] A dye is a substance used to add colour, for example to cells or tissue. A dye may comprise a chromophore, which is a moiety which absorbs light at a particular wavelength and reflects light at a wavelength in the visible spectrum, thereby appearing coloured.

[0046] The process of tattoo removal will be described with reference to figures 1 to 5. Figure 1 shows a schematic cross section of skin 100. The skin 100 has an upper layer, the epidermis 101 , a dermis layer 102 and a hypodermis layer 103. In undamaged skin, the epidermis is the outer layer of the skin, and the dermis is a layer between the epidermis and the hypodermis. The epidermis 101 has an upper surface exposed, e.g. to air, at the outer surface of the skin. On the opposing side of the epidermis, the 6 KSF01 -134375PC epidermis has an inner boundary at its interface 104 with the dermis 102. The interface 104 comprises a basement membrane, also called a basal membrane. The dermis 102 comprises connective tissue, such as collagen, reticular and elastic fibres. The dermis 102 comprises a papillary layer, proximal to the epidermis, and a reticular layer, proximal to the hypodermis. The papillary layer is composed of looser connective tissue; that is to say connective tissue that is looser than the general density of the reticular layer. The reticular layer is composed of denser connective tissue; that is to say connective tissue that is denser than the general density of the papillary layer. The papillary and reticular layers may not be clearly distinguishable from one another, there is a gradient of transition from papillary to reticular as the depth from the surface of the skin increases.

[0047] Dye introduced only to the epidermis 101 will be removed by the natural exfoliation of epidermal cells over time. It is not believed to be possible to produce a lasting tattoo by superficial application of a dye. It is believed to be necessary to situate dye in a deeper layer of skin than the epidermis to permit the formation of a lasting tattoo. A dye tattoo comprises dye in the dermis layer 102. A dye tattoo comprises dye that is beneath the basement membrane 104 of the epidermis 101. A dye tattoo may be a durable tattoo that has a dye as its principal colouring component. A dye tattoo may be a durable tattoo that has a dye as its only colouring component.

[0048] The tattoo may be applied as set out in our co-pending application entitled “Dye Tattoo”, or as set out in co-pending application “Tattooing”.

[0049] The term ‘dye tattoo’ as used herein preferably means a tattoo made by a dye. As used herein ‘dye’ preferably means a substance or combination of substances capable of producing a visible colour in the dermis. A dye may be a colouring agent in which the chromophores are in solution in a solvent. A dye is distinct from conventional tattoo inks which comprise pigments, especially inorganic pigments. These pigments may be solid particles having a size between 200 nm - 200 pm. The presently described methods of tattoo removal are effective for dye tattoos rather than the removal of conventional pigment inks. 7 KSF01 -134375PC

[0050] The term ‘dye’ preferably includes materials which are colourless or weakly coloured prior to fixation in the skin but which develop or reveal colour when situated in the skin. Such dyes may develop colour as a result of a chemical and / or physical reaction, for example by a change in pH, by oxidation or reduction, a photochemical activation, covalent bonding to constituents of the skin, or a combination of two or more thereof.

[0051] Figure 2 shows a schematic cross section of skin and a tattoo removal process. The process is represented as progressing from left to right in figure 2. Skin 200 comprises an epidermal layer 201 , a dermal layer 202, and a hypodermal layer 203. A region of dye in the dermis is indicated at 204. The method of removal is suitable for degrading dye in the dermis. A removal compound 205 is applied to the skin. The removal compound 205 degrades the dye, a region of dye undergoing degradation by the removal compound is indicated by region 206 in the dermal layer 202. The removal compound is removed from the region of skin, for example by applying a liquid 207. The dye 204 that was present in the dermis is removed by being degraded by the removal compound. A region in the dermis having had the dye removed is indicated at 208.

[0052] The removal compound may be in powder form. The removal compound in the form of a powder may at least partially dissolve in extracellular fluid and / or intercellular fluid. The removal compound may dissolve in exudates from the skin and may enter the dermis along a concentration gradient. The removal compound may alternatively be provided in solution.

[0053] Preferably the removal compound is selected for providing a combination of properties, specifically (i) being tolerable in the skin, i.e. not so harmful that irreparable damage is done to the skin or excessive pain inflicted, and (ii) being able to degrade a dye.

[0054] The removal compound may comprise one or more of the following: a reducing agent, oxidizing agent, chelating agent, nucleophilic species, or complex-disrupting agents. Preferably the reagents are biocompatible or tolerable to skin. The removal compound may be formulated as a powder, solution, suspension, or gel. The removal compound is selected to degrade, decolorize, or solubilize dyes which have undergone fixation in 8 KSF01-134375PC the dermis. A dye tattoo may have been ‘fixed’ in the dermis by reaction with components of the dermis or extracellular matrix. The dye may have been fixed by binding of the dye to one or more components of the extracellular matrix. Such components include fibrous proteins (e.g. collagen, elastin), cell-adhesive glycoproteins (e.g. fibronectin, laminin), proteoglycans and glycosaminoglycans (e.g. hyaluronic acid, chondroitin sulfate, dermatan sulfate, heparan sulfate), constituents of the basement membrane, and constituents of the papillary dermis. Advantageously, the methods of tattoo removal described herein are suitable for removing such fixed dyes. The tattoo removal is preferably suitable for removing dye from the dermis and / or extracellular matrix.

[0055] Examples of reagents for dye degradation or decolorization, suitable for use in or as a removal compound include: reducing agents, oxidizing and / or bleaching agents, nucleophilic and / or hydrolytic agents, chelating agents, complex-disrupting agents, or a combination of two or more thereof. Further examples of each type of reagent will be given.

[0056] Reducing agents may function as electron donors. Reducing agents have been found to be effective for degradation of dyes of the following type: azo, quinone-imine, indigoid, reactive-dye chromophores. Examples of reducing agents include sodium dithionite (Na2S2O4, also known as sodium hydrosulfite), sodium bisulfite (NaHSOs), sodium metabisulfite (Na2S20s), sodium sulfite (Na2SOs), thiourea dioxide (formamidine sulfinic acid), ascorbic acid, sodium ascorbate, stannous chloride (SnCI2), cysteamine, sodium 2-mercaptoethanesulfonate (MESNA) for thiol-mediated reduction, sodium borohydride (NaBFU), and borane complexes (e.g. in buffered low-concentration solution).

[0057] Oxidizing and / or bleaching agents are effective for oxidative cleavage of conjugated systems, catechol or polymerised adducts e.g. polydopamine-type dyes. Examples of oxidizing agents include hydrogen peroxide (H2O2), carbamide peroxide, sodium percarbonate, perborate, persulfate (ammonium or potassium), sodium hypochlorite (NaOCI), sodium periodate (Nal04), peracetic acid, performic acid, and benzoyl peroxide. Sodium periodate (NaIC ) has been found to be effective for cleavage of 9 KSF01 -134375PC vicinal diols in catechol-based dyes. Advantageously, benzoyl peroxide is highly tolerable in skin.

[0058] Nucleophilic and / or hydrolytic agents are effective for cleavage of dye-tissue covalent linkages such as sulfone, triazine, or imine bonds. Examples of nucleophilic agents include alkaline hydrolytic agents (having a pH of about 8 to about 11 ) such as sodium or potassium carbonate, bicarbonate and hydroxide. Further examples of nucleophilic agents include hydroxylamine, methoxyamine, nucleophilic amines such as ethanolamine and morpholine, thiols such as MESNA, cysteamine, glutathione, weak acids (having a pH of about 3 to about 5) such as citric acid, lactic acid, and acetic acid. Methoxyamine has been found to be effective for disruption of imine / Schiff-base linkages. Thiols has been found to be suitable to attack sulfone or epoxide adducts. Weak acids have been found to be suitable to catalyse hydrolysis of triazine or epoxide bonds

[0059] Chelating and / or complex-disrupting agents are effective removal compounds for dyes which form coordinate bonds to metal ions (such as Ca2+, Fe3+, Cu2+, Zn2+). Examples of chelating agents include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), ethylene glycol bis([3-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), citric acid, tartaric acid, deferoxamine (an iron chelator), and penicillamine (a copper chelator).

[0060] Further examples of removal compounds include enzymatic or photo-activated processes such as peroxidase- or laccase-catalysed oxidation, and UV-assisted photobleaching.

[0061] The removal compound may comprise surfactants or penetration enhancers (e.g., phospholipids, polysorbates, betaines) to facilitate reagent diffusion through the voids.

[0062] A combined approach may be used to apply removal compounds. First and second removal compounds may be mixed together and applied to the skin. Alternatively, a sequential approach may be taken in which a first removal compound is applied, followed by a second removal compound. A sequential application of a reducing agent and an oxidizing agent may be utilized to degrade a dye by redox. 10 KSF01 -134375PC

[0063] Preferably the removal compound is a decolourising agent. The removal compound may comprise a reducing agent. The removal compound may comprise sodium. The removal compound may comprise sodium dithionite, sodium bisulfite, sodium metasilicate, or a combination of two or more thereof. Sodium dithionite is also known as sodium hydrosulfite.

[0064] The removal compound may comprise an oxidising agent. The removal compound may comprise a bleaching agent. The removal compound may comprise sodium hypochlorite in solution.

[0065] Degradation of the dye may include decomposition and / or decolourisation of the dye. Decolourisation of the dye may be achieved by shifting the electron density of a coloured dye molecule. In an example, sodium dithionite reduces a dye molecule by donating an electron to the dye molecule.

[0066] Thus, removal of the tattoo may comprise substantially reducing the visual prominence of the tattoo or treating the skin such that the tattoo cannot be seen. The removal compound balances efficacy and biocompatibility in order to limit skin irritation while achieving degradation of the dye.

[0067] Figure 3 shows steps of a tattoo removal process in a region of skin 300. The process is represented as progressing from left to right in figure 3. A dye tattoo comprises dye 304 in the dermis. Figure 3 shows the region of skin 300 having a void 301 extending through the epidermis layer and into the dermis layer. The void may be made by any suitable means, for example by using microneedles. In another example, voids may be made by using a laser. The laser may be a CO2 laser. The laser may be a pulsed laser. The void 301 made be formed by laser ablation. The void may have a columnar profile, the void may be substantially cylindrical. The cross-section of the void may be substantially constant over the majority of the length of the void. The void made be formed at a location of a region of dye in the dermis. 11 KSF01 -134375PC

[0068] A removal compound 305 is applied to the skin. The removal compound 305 penetrates the skin via the void 301 . The removal compound 305 degrades the dye, a region of degraded dye is indicated by region 306.

[0069] The removal compound is at least partially removed from the region of skin, for example by applying a liquid 307. The liquid may be for example water, a weak acid having a pH of 3 - 7, or a weak alkali having a pH of 7 - 9. The removal compound may be neutralised to about pH 7 by the application of a liquid. The application of a liquid 307 to the skin may cause the liquid 307 to move into the void 301 and to flush out dye from the skin. The void may function as a channel 308 for dye to be removed from the skin. The dye may move along a concentration gradient in the channel 308. Without being bound by theory, it is thought that the dye is drawn out of the skin by capillary action.

[0070] A partially healed void 309 is shown. After the application and removal of the removal compound, the void in the skin will begin to heal. The profile of the void is reduced in depth and extent from the void 301 . The skin heals over time by a biological healing process involving platelets, macrophages and fibroblasts.

[0071] The natural healing process may be supported by the application of topical agents to the voids after the dye is removed. For example, soothing agents such as pantothenic acid and ceramides may be applied. An antiseptic may be applied to the treated area, for example chlorhexidine. The healing process may be supported by applying a sterile bandage to the treated area of skin. An anti-pigmentation agent may be applied to the treated area of skin to reduce the risk of pigmentation. The anti-pigmentation agent may be a retinoid.

[0072] Put another way, the process of dye tattoo removal described above involves the following steps in order:

[0073] 1 . One or more voids are made from the surface of the skin into the dermis, or at least through the basement membrane situated between the epidermis and dermis.

[0074] 2. A removal compound is applied to the skin over the region of the voids. The removal compound may enter the voids by capillary action. The removal compound may dissolve in intercellular fluid and / or exudates due to the voids being made in the skin. 12 KSF01 -134375PC

[0075] Ideally, the removal compound is applied immediately after they voids have been formed.

[0076] 3. The removal compound is at least partially removed from the region of skin. Preferably the removal compound is washed from the skin. Subsequently, topical agents may be applied to the treated area such as an antiseptic.

[0077] In an example, a powdered removal compound is applied to the skin in a region of a dye tattoo. Preferably, the dye tattoo is at least partially exposed to promote removal. In this example, the removal compound is applied in a dry form. The removal compound may dissolve in dermal exudate. Dermal exudate may comprise extracellular fluid (which may include interstitial fluid, plasma, and transcellular fluid) and / or blood and / or sweat. The dermal layer of skin may exude fluid in response to being penetrated and / or the epidermal layer being removed to expose the dermis. The removal compound may enter the skin along a concentration gradient. The removal compound may flow from a region of relatively higher concentration at the surface of the skin to a region of relatively lower concentration inside the dermis.

[0078] In an illustrative example, 1 g of sodium dithionite powder is sprinkled onto a region of skin that has been microneedled. The sodium dithionite dissolves in dermal exudate and enters the dermis. Dye present in the dermis is decoloured by reaction with the sodium dithionite. From the point of application of the sodium dithionite, a waiting period of 10 minutes is observed. At the end of the waiting period, the region of skin is washed thoroughly with distilled water.

[0079] The removal compound may comprise one or more chemical components.

[0080] Figure 4 shows an exemplary system for dye tattoo removal. The system 400 comprises a scanner 401 and a dermal penetration device 402 for penetrating into the skin. The dermal penetration device 402 is preferably for making voids in the skin. Microneedling may be used to penetrate the skin. A plurality of needles having a diameter less than 1 mm may be used. The device 402 may be a laser. The laser may be a CO2 laser. The laser may be a pulsed laser. The laser may comprise a lens 403 and, in operation, a beam 404. The device 402 is connected to a processor 405. The system could be implemented by one or more computer devices which could be co- 13 KSF01 -134375PC located or distributed across multiple locations. The processor 405 comprises or is in communication with a memory storing in non-transient form instructions executable by the processor to cause the processor to implement functions of the system as described below. The system 400 comprises a display 406, the display may be configured to receive user-input and to display content to a user of the system. The processor 405 may be in communication with the display 406. Alternatively, the display 406 may be in communication with a different processor. The system may further comprise a dispenser 407 for dispensing a removal compound.

[0081] The scanner 401 is suitable for imaging a region of tattooed skin. For example, the scanner may comprise a camera, binocular imaging hardware, an infrared imaging device, or a LIDAR sensor. It is advantageous to determine the depth and topography of tattooed skin so that the device 402 can make voids at the appropriate depth in the skin. It is advantageous to be able to determine the depth and topography of a region of tattooed skin prior to tattoo removal so that the removal compound can be automatically applied.

[0082] The scanner 401 is preferably configured to send an indication of a scanned region of skin to the processor 405. The processor 405 may generate a planned arrangement of voids to be marked in response to data received from the scanner. The processor may determine adjustments to a pre-planned arrangement of voids to be marked in response to the scanner data. For example, in a 10cm by 10cm region of tattooed skin scanned on a user’s forearm, the imaged areas at the outer and inner forearm will be detected as curved and further away from the scanner while the centre of the forearm will be detected as relatively planar and closer to the scanner. An arrangement of voids may be determined in response to the scanned region of tattooed skin. For example, voids may be positioned on lines of the tattoo detected by the scanner. The arrangement of voids may be modified in response to the determined topography of the region of skin, for example to make deeper voids at regions detected as being further from the scanner. In other words, regions further from the scanner may be designated as requiring a greater depth than regions closer to the scanner. 14 KSF01 -134375PC

[0083] The system 400 may further comprise a dispenser 407 for dispensing a removal compound. In an exemplary process of dye tattoo removal, an area of tattooed skin is scanned, voids are made in the scanned area of tattooed skin, and a removal compound is applied to the area containing voids. The dispenser may comprise a nozzle or movable opening that is controlled to open and release the removal compound.

[0084] The system is particularly advantageous as it permits the removal of a tattoo without the need for a trained human operator. This is especially beneficial for large tattoos, which may take several hours to be removed by a conventional laser removal process. It is further advantageous as only a single session of removal according to the described process might be required to significantly remove a dye tattoo.

[0085] An exemplary use of the system 400 will be described for illustration. A user of the system having a dye tattoo initiates the system by making a selection on the display 406. The display provides instructions to the user to position their tattooed skin under the scanner 401 . The scanner images the region of tattooed skin. The scanner sends an indication of the scanned region of skin to the processor 405. The processor generates a plan for removal of the tattoo, the plan may comprise positional instructions to move the dermal penetration device 402, the plan may comprise an arrangement of sites to be penetrated by the device 402. Once the plan for removal has been generated, the display 406 provides instructions to the user to move their tattooed skin under the dermal penetration device 402. The scanner may detect when the treated region is optimally positioned relative to the device 402 and provide feedback to the user. The region of tattooed skin is penetrated to expose the dermis, for example by laser ablation to form voids in the epidermis and basement membrane. This region of skin will be referred to as the treated region. The display provides instructions to the user to move the treated region proximal to the dispenser 407. The scanner may detect when the treated region is optimally positioned relative to the dispenser and provide feedback to the user. The dispenser 407 dispenses a removal compound which enters the treated region. A subsequent washing fluid may be dispensed to remove the removal compound. Amounts of the removal compound may remain after washing, but suitably the majority is removed from the skin. 15 KSF01 -134375PC

[0086] Figure 5 shows a top-down view of a region of skin 500. Voids 501 in the skin are made by any suitable method, such as by laser ablation. Each void is seen as a hole in the top-down view of figure 5. Each void may have a diameter of between 10 pm to 500 pm, preferably between 50 pm to 150 pm. Respective voids may have a horizontal spacing 502 of at least 50 pm, preferably at least 100 pm. Respective voids may have a vertical spacing 503 of at least 50 pm, preferably at least 100 pm. The minimum spacing being of this length ensures that there is enough skin surrounding a void to allow good healing of the area of skin after the removal process has taken place. The horizontal spacing 502 and vertical spacing 503 may be equal.

[0087] The total depth of the void will depend on the thickness of the epidermis. The thickness of the epidermis varies for different persons, and at different body parts of the same person (for example, the eyelid epidermis is particularly thin, while the heel epidermis is significantly thicker). Preferably the voids extend through the basement membrane so that the removal compound can penetrate the dermis. Preferably the voids extend from the epidermis-dermis interface into the dermis by a depth of 10 pm - 80 pm, preferably about 50 pm, for instance in the range from 45 pm to 55 pm.

[0088] The equipment described above with reference to figure 4 is preferably programmable to form a series of voids in the skin of a subject. The equipment may image the skin to determine its distance from a reference plane. Using that information the equipment may adjust the process of forming the voids so that each void has a desired depth. The desired depth may depend on the depth of the dermis at the location of the void. The equipment may be pre-programmed to estimate the depth of the dermis based on the scanning of the subject and / or on information provided to it such as the age, height and weight of the subject. The equipment may then adjust the power of an optical beam and / or the distance from the skin of a head from which the beam is generated so as to form voids of the desired depth. The equipment may be programmed with a scanned image of the tattoo to be removed. The equipment may then determine a pattern of voids to apply for removing that tattoo. The equipment may determine the pattern of voids so that voids have a higher density in darker regions of the tattoo and a lower density in lighter regions of the tattoo (which contain less dye). 16 KSF01 -134375PC

[0089] The system and methods of dye tattoo removal described herein are distinct from conventional laser tattoo removal techniques which degrade pigment tattoos by causing pigment particles to breaking down. The systems and methods herein remove a dye tattoo by targeting the dye itself with a removal compound. In particular, the removal compound is selectively applied to the dermis in order to degrade the dye. The system and method of removal advantageously cause minimal damage to the tattooed skin by the formation of voids into the dermis to deliver the removal compound. In contrast, known techniques of chemical tattoo removal involve the application of bleaching agents to the epidermis which can induce the entire region of skin to peel. A chemical peel, where tattoo removal occurs through the destruction of skin structures and removal of a layer of necrotic tissue, is significantly more damaging than the removal techniques described herein.

[0090] The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description, it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

[0091] The foregoing description of example embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. Many modifications and variations are possible in light of this disclosure. It is intended that the scope of the present disclosure be limited not by this detailed description, but rather by the claims appended hereto.

Claims

17 KSF01-134375PCCLAIMS1 . A method of removing a dye tattoo from a region of skin comprising: creating voids in the region of skin, the voids extending from a surface of the epidermis into the dermis; applying a removal compound to the region of skin; degrading the dye by the action of the removal compound; and removing the removal compound from the region of skin.

2. A method as claimed in claim 1 , wherein removing the removal compound comprises washing the region of skin.

3. A method as claimed in any preceding claim, wherein the removal compound applied is in the form of a powder.

4. A method as claimed in any preceding claim, wherein the dye is degraded by decolourisation.

5. A method as claimed in any preceding claim, wherein the removal compound comprises a reducing agent.

6. A method as claimed in any preceding claim, wherein the removal compound comprises a sodium compound.

7. A method as claimed in claim 6, wherein the sodium compound is sodium dithionite, sodium bisulfite, sodium metasilicate, or a combination of two or more thereof.

8. A method as claimed in any preceding claim, wherein the voids do not extend through the dermis into the hypodermis.

9. A method as claimed in any preceding claim, wherein the voids in the region of skin are created by a laser.18 KSF01 -134375PC10. A method as claimed in any preceding claim, wherein respective voids are spaced apart by a distance of at least 50 pm, preferably 100 pm.11 . A method as claimed in any preceding claim, wherein creating voids comprises at least partially removing a basement membrane, the basement membrane being between the epidermis and the dermis.

12. A method as claimed in any preceding claim, further comprising applying an antipigmentation agent to the region of skin.

13. A method as claimed in any preceding claim, wherein the dye tattoo comprises a reactive dye molecule.

14. A system for dye tattoo removal comprising: a sensor for sensing a location of the surface of a region of tattooed skin of a subject; a dermal penetration device for creating voids in the region of skin, the voids extending from a surface of the epidermis into the dermis; a controller responsive to the sensor to control the dermal penetration device to create voids into but not through the dermis in the region of skin; and a dispenser for dispensing a removal compound to the region of skin.

15. A system as claimed in claim 14, wherein the dermal penetration device comprises a laser.

16. A system as claimed in claim 15, wherein the controller is configured to cause the laser to create voids in the dermis which do not extend through the dermis into the hypodermis.

17. A system as claimed in any of claims 14 to 16, wherein the dispenser contains a removal compound comprising a reducing agent.

18. A system as claimed in claim 17, wherein the removal compound comprises a sodium compound.19 KSF01 -134375PC19. A system as claimed in claim 18, wherein the sodium compound is sodium dithionite, sodium bisulfite, sodium metasilicate, or a combination of two or more thereof.

20. A system as claimed in any of claims 14 to 19, further comprising a processor and a memory, the memory storing in non-transient form instructions executable by the processor to cause the processor to implement functions of the system.

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