ADHESIVE SKIN PATCH AND METHOD FOR MANUFACTURING THE ADHESIVE SKIN PATCH - Patent application

Abstract

An adhesive skin patch and method that allows for the provision of an adhesive skin patch that is very thin, easily conforms to deformations of the skin, and yet can be manufactured in a sequential industrial process that can be automated for commercial production. The adhesive skin patch includes a conductive portion that provides contact to the skin and access for external electrical contacts.

Description

[Technical field]

[0001] This document relates to printed electronics and, in particular, to an improved adhesive skin patch and an improved method for manufacturing the adhesive skin patch. [Background technology]

[0002] The use of monitoring applications that process information from direct skin sensor interaction is continually growing. For example, continuous monitoring of a person's sleep quality, physical condition, or exercise effectiveness is already quite commonplace. Diagnostic applications attempt to observe selected vital signs of the monitored subject for longer periods outside of the laboratory environment. For these purposes, various kinds of sensors and electrodes are fitted into, for example, watches, rings, straps, and belts.

[0003] One important type of on-skin device is an adhesively applied, removable skin patch, which has already been used for a considerable number of years in medical applications. However, an affordable and comfortable to wear skin patch for frequent and / or long-term use is not yet available. Many commercially available skin patches still include a stiff substrate sheet that feels uncomfortable when glued onto the skin, particularly for longer periods of time. Those skin patches also tend to include components that protrude outward and cannot be discreetly hidden under a person's clothing. At least some of the components or connections are even exposed, which makes the patch unable to be used safely in moist or wet conditions.

[0004] Some more recent solutions provide skin patches formed from a hybrid combination of flexible and integrated rigid components rather than including a traditional reinforcing substrate. However, these skin patches also suffer from the same lack of comfort in use, and due to the level of complex integration, they tend to be relatively expensive to manufacture. Such hybrid solutions are not really suitable for use in applications that require the skin patch to be comfortable to use, easily replaceable, and disposed of after use of the skin patch.

[0005] Epidermal electronics is a new class of wearable technology in which ultra-thin, lightweight, and flexible or even stretchable devices are attached to the skin by conformal contact. However, despite considerable progress in research, several limiting factors have hindered the exploitation of epidermal electronics in practical applications. When in use, skin patches are subject to mechanical deformation and humidity changes, and providing a structure that is thin and flexible and that adequately protects the conductive parts from moisture is a complex technical challenge. In addition, so far only customized fabrication methods have been used to produce the samples shown, and the connectivity issues remain to be fully resolved. Although images of very thin patches with underside skin contacts have already appeared in publications, the output connections shown rely solely on additional external wiring configurations. Summary of the Invention [Problem to be solved by the invention]

[0006] It is an object of the present disclosure to provide adhesive skin patches and methods that allow for the provision of adhesive skin patches that are very thin, easily conform to deformations of the skin, and yet can be manufactured in a sequential industrial process that can be automated for commercial production. [Means for solving the problem]

[0007] The object of the present invention is achieved by an adhesive skin patch and a method, which are characterized in that they are recited in the independent claims. Exemplary embodiments of the present disclosure are disclosed in the dependent claims.

[0008] In the following, examples for the implementation of the invention will be explained in more detail with reference to the accompanying drawings. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 1 illustrates an example layer structure for an exemplary adhesive skin patch. [Figure 1B] FIG. 1 illustrates an example layer structure for an exemplary adhesive skin patch. [Figure 1C] FIG. 1 illustrates an example layer structure for an exemplary adhesive skin patch. [Diagram 2] FIG. 2 shows a top view of the on-skin portion of an adhesive skin patch. [Diagram 3] FIG. 1 illustrates steps in a method for creating a layered structure for an adhesive skin patch. [Figure 4] FIG. 1 includes three images showing an exemplary skin patch formed by a layered structure. [Diagram 5] FIG. 1 illustrates an advantageous use case for an adhesive skin patch. [Figure 6A] FIG. 1 illustrates layers of an upper skin portion in an exemplary multi-layer stack for a skin patch. [Figure 6B] FIG. 1 illustrates layers of an upper skin portion in an exemplary multi-layer stack for a skin patch. [Figure 6C] FIG. 1 illustrates layers of an upper skin portion in an exemplary multi-layer stack for a skin patch. [Figure 7A] FIG. 13 illustrates layers of the upper skin portion in a further exemplary multi-layer stack for a skin patch. [Figure 7B]FIG. 13 illustrates layers of the upper skin portion in a further exemplary multi-layer stack for a skin patch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 1A to 1C illustrate example layer structures for an adhesive skin patch applicable as a wearable electronic device, or part of a wearable electronic device, that collects information about a subject through contacts placed on the subject's skin.

[0011] An adhesive patch that conformably settles on the skin requires that it be so thin that it cannot be manufactured or moved onto the skin without some reinforcing support structure. The stack of Figures 1A to 1C thus shows an on-skin portion 100 and a releasable portion 102, where the on-skin portion 100 forms a skin patch that remains attached to the skin of the subject during use, and the releasable portion 102 can be removed from the stack after the on-skin portion 100 is safely and conformably attached onto the skin. The releasable portion provides the necessary reinforcement for the various manufacturing and moving steps that precede the actual use of the adhesive patch.

[0012] The term layer in this document refers to a thickness of deposited material that fully or partially covers an underlying surface formed by one or more previously deposited layers. The underlying surface may be planar, for example if it is provided by a planar substrate sheet, or it may be curved resulting from a pattern or organization in a previously deposited layer. In successive deposition stages, the currently deposited layer tends to conform to the contours of the underlying surface, for example filling in underlying patterned recesses if such exist in the underlying layer.

[0013] The term connector in this document refers to a conductive element including a connector area or a combination of a connector area and a sensing area. The connector may be realized as a one layer pattern or as a pattern including two layers, a layer for the connector area and a layer for the sensing area. Figures 1A to 6B show an example where the connector is provided as a conductive layer pattern. Figure 7 shows an example where the connector area is realized by a two layer pattern, one stacked on top of the other.

[0014] FIG. 1A shows a schematic example of a basic layer stack for a skin patch. In this example, the releasable portion 102 includes a layer of liquid soluble polymer 106. The liquid soluble polymer 106 is a substance that functions in the layer stack as a carrier for the on-skin portion 100. The liquid soluble polymer 106 is a polymer material that is robust enough to act as a substrate for an accumulated web or sheet that is formed in the layer deposition step of an industrial manufacturing process. The liquid soluble polymer 106 remains attached to the on-skin portion 100 during the fabrication and transfer stages, but can be easily dissolved when the on-skin portion is attached onto the skin. Advantageously, the liquid soluble polymer is soluble in water so that the layer can be very easily washed off after the on-skin portion is placed on the skin. However, polymers that are soluble in other liquid solvents may be applied within the scope. The layer of liquid soluble polymer 106 is configured to be significantly less elastic than the on-skin portion, such that it is not stretchy in nature, but rather provides mechanical support to the on-skin patch, thus preventing wrinkling or stiffening of the ultra-thin portion during the application step. For example, the material composition of the liquid soluble polymer may be selected to provide the required stiffness, and / or the layer of liquid soluble polymer 106 may be significantly thicker than the on-skin portion 100.

[0015] FIG. 1B shows a schematic representation of an alternative layer stack, in which the releasable part is a bilayer combination including a further support layer 104. This bilayer structure is advantageous for implementations in which the mechanical stresses on the layer stack at certain stages are high, for example when the layer stack is manufactured by roll-to-roll processing. The support layer 104 is thus advantageously made of a material that is flexible enough for roll-to-roll processing, but robust enough to act as a substrate for an accumulated web or sheet formed in the layer deposition step of the industrial manufacturing process. The support layer 104 can also be used to protect other parts of the skin patch on its way to the user. For example, the support layer 104 can be designed to be removed from the layer of liquid soluble polymer 106 before the skin patch is applied onto the skin, so that at the time of application the skin patch only includes the layer stack of FIG. 1A. Alternatively, the support layer 104 may be designed to be removed from the layer of liquid soluble polymer 106 after the skin patch is applied onto the skin, so that both the layer of liquid soluble polymer 106 and the support layer 104 protect the thin and easily crumpled on-skin portion 100 until it is safely applied onto the skin. Various materials may be used for the support layer, examples of such materials include polymers, paper, paperboard, and the like. Advantageously, the support layer is made of polyethylene terephthalate (PET), which is very well suited for this purpose due to its material properties. PET films are well adapted to roll-to-roll processing, and PET films that are elastic enough for roll-to-roll processing still support the softer and more elastic parts of the layer stack very well. PET film is also easy to use when a support layer needs to be detached from the layer of liquid soluble polymer 106 .

[0016] The on-skin portion 100 is a skin patch, which includes an adhesive layer, an elastic layer, and a conductive layer enclosed between the adhesive layer and the elastic layer in the basic form of the skin patch. Figures 1A and 1B show an example of the on-skin portion 100, which includes a first layer 108 of polysiloxane, a conductor in the form of a conductive layer 110, and an adhesive layer 114. The term polysiloxane here refers to polymerized siloxanes, also known as silicones. Silicones exhibit many properties that make them useful for use in skin patches, such as low thermal conductivity, low chemical reactivity, low toxicity, thermal stability, electrical insulation, to mention a few. In the context of very thin skin patches, it is particularly advantageous that the selected polysiloxane can be deposited as a fluid onto the underlying layer stack to create a patterned form, and then cured to function as an elastic solid. The term elastic solid refers here to a polymer that has a solid form but provides rubber-like elasticity. An advantageous type of polysiloxane for these illustrative examples includes silicone compositions that include polydimethylsiloxane (PDMS), also known as dimethylpolysiloxane or dimethicone. The mechanical properties of PDMS are influenced by various factors that can be determined before the PDMS is cured, so that they are relatively easy to adjust to function after curing as an elastic solid. Due to the viscoelastic properties of PDMS before curing, it is also well suited for deposition onto a accumulating web or sheet in a sequential industrial process.

[0017] The adhesive layer may be provided with any type of conformal skin-friendly adhesive, for example selected from commercially available acrylic and silicone skin adhesives. The essential requirement for the embodiment of Figures 1A and 1B is that the adhesive layer material is capable of being formed into an elastic layer structure that sticks to the skin but maintains its patterned form during use.

[0018] 1C shows an example of an on-skin portion 100 including a first layer of polysiloxane 108, a conductive layer 110, a second layer of polysiloxane 112, and an adhesive layer 114. The second layer of polysiloxane may be included in the stack to provide an additional protective and / or electrically insulating layer between the conductive and adhesive layers.

[0019] In all the examples of Figures 1A to 1C, the conductor is a conductive layer 110 formed into a pattern including a conductor region 116 and a sensing region 118 in electrical connection with the conductor region 116. In some applications, the conductor region 116 and the sensing region 118 may at least partially overlap. As can be seen from all Figures 1A to 1C, the first layer 108 of polysiloxane includes an opening 120 for at least a portion of the conductor region 116. The expression "opening for" in this context can be interpreted by considering that the layers on which the on-skin portion is deposited form a planar reference plane 150 that extends in two mutually orthogonal in-plane directions IP1 and IP2, and that the layer stack is grown in an out-of-plane direction OP that is orthogonal to the two in-plane directions, as shown in Figures 1A to 1C. An opening in one layer relative to a portion in another layer means that the opening is a discontinuity in the layer thickness and that the projection of the opening on a reference plane and the projection of the portion in the other layer at least partially coincide. In sequential industrial layer deposition processes, openings in lower layers are typically at least partially filled by material of the next deposited layer. This means, in fact, that the resulting structure does not substantially contain void space, and the term opening does not refer to an empty recess in this context.

[0020] Thus, the opening 120 in FIG. 1A is a discontinuity in the layer structure of the first layer 108 of polysiloxane, and the projection of the opening 120 and the projection of the conductor region 116 on the reference plane at least partially coincide. When the layer of the conductor region is deposited, it at least partially fills the opening 120 and can bring the surface of the conductive part locally in line with the side of the first layer 108 of polysiloxane. When the releasable part of the liquid-soluble polymer 106 is removed, this locally exposed part of the first layer 108 of polysiloxane and also of the conductor region 116 is exposed. Thus, the layered structure aspect is beginning to be innovatively used to provide contacts for external electrical connections. During the layer deposition, the fluid material of the conductor region 116 at least partially fills the opening 120, thus providing an exposed interface for the conductive path to the sensing region 118. This interface for external electrical connection becomes available for use without further operation or additional wiring arrangements when the liquid soluble polymer 106 is dispersed by a solvent from the surface of the layer stack. As will be explained in more detail later, the opening 120 may be provided by conventional patterning means in a sequential on-going industrial process, but due to the specific layer stack structure presented herein, the opening 120 provides an output for electrical information available through the skin contact portion of the sensing region 118.

[0021] The sensing area 118 here represents a portion of a layer pattern comprising a material or a structured combination of materials, certain electrical properties of which change as a function of a change detectable on the skin of a subject. Such changes may be, for example, a change in surface potential, a chemical change, a temperature change, or a mechanical change (e.g., strain). In the example of FIG. 1, the sensing area comprises a combination of silver / silver chloride paste (Ag / AgCl) that is responsive to biopotentials generated by excitable cells. This response can be detected as a measurable signal by an external electrical connection. Examples of measurable biopotential signals include electrocardiogram (ECG), electromyogram (EMG), electroencephalogram (EEG), and electrooculogram (EOG), to name a few.

[0022] 1A and 1B, as shown in , the adhesive layer 114 includes an opening 124 for at least a part of the sensing area 118. Again, this expression means that the opening 124 is a discontinuity in the layer thickness of the adhesive layer 114, and that the projection of the opening 124 and the projection of the sensing area 118 on the reference plane 150 at least partially coincide. The role of the opening 124 is to leave the sensing area 118 exposed on the skin side. The adhesive layer 114 is very thin, the whole layer structure of the on-skin portion 100 is very flexible and conformal, and human skin is very flexible, so that in fact this opening does not form an air gap space between the skin and the sensing area 118, but the sensing area presses against the skin in use so that direct skin contact can be achieved for measurement by the sensing area 118.

[0023] In configuration 1C, the polysiloxane second layer 112 is between the conductive layer and the adhesive layer 114 and further includes an opening 122 for at least a portion of the sensing area 118. The opening 122 is thus a discontinuity in the layer thickness of the polysiloxane second layer 112, and the projection of the opening 122 and the projection of the sensing area 118 on the reference plane at least partially coincide. The role of the opening 122 is to combine with an opening 124 on the adhesive layer 114 to expose the sensing area 118 on the skin side. The second layer of polysiloxane 112 is very thin and the entire layer structure of the on-skin portion 100 is very flexible and conformal; human skin is very flexible, so that in fact the openings in the second layer of polysiloxane 112 and the adhesive layer do not form an void space between the skin and the sensing area 118, but rather the sensing area presses against the skin in use so that direct skin contact can be achieved for measurement.

[0024] As can be seen from Fig. 1C, despite the parts of the conductive layer 110 being intentionally left exposed through the openings 120, 122, the remainder of the conductive layer 110 is tightly pressed between the first layer of polysiloxane 108 and the second layer of polysiloxane 112. This means that in the areas beyond the openings 120, 122, the first layer of polysiloxane and the second layer of polysiloxane surround the conductive layer in a watertight manner. By reducing the exposure to changes in humidity, this packaged layer structure further improves the operational stability of the measurement.

[0025] Due to the required conformality, the thickness of the adhesive layer is preferably less than 100 μm, more preferably between 5 μm and 15 μm. The thickness of the conductive layer is preferably less than 30 μm, more preferably between 5 μm and 15 μm. The thickness of the polysiloxane layer is preferably less than 100 μm, more preferably between 5 μm and 15 μm. The thickness of the conductive layer is preferably less than 30 μm, more preferably between 5 μm and 15 μm. The thickness of the liquid soluble polymer layer is preferably less than 200 μm, more preferably between 50 μm and 100 μm. The thickness of the support layer is preferably less than 200 μm, more preferably between 20 μm and 50 μm.

[0026] FIG. 2 shows a top view of the on-skin portion 200 of the adhesive skin patch illustrated by the layer structure of FIG. 1A to FIG. 1C after removal of the releasable portion. The structure is described with reference to FIG. 1C, but as already explained, the skin patch does not necessarily include a second layer of polysiloxane. The outer surface of the on-skin portion 200 is formed from a surface of the first layer of polysiloxane 202 that includes an opening 204. A first portion 206 of the conductor area is accessible for external electrical connection through the opening 204 in the first layer of polysiloxane 202. A second portion 208 of the conductor area is intimately enclosed under the outer surface of the on-skin portion 200 between the first layer of polysiloxane 202 and the second layer of polysiloxane or adhesive layer under the first layer of polysiloxane 202. The second portion 208 of the conductor area ends at the sensing area 210, which is further secured under the first layer of polysiloxane 202 but exposed to the skin underneath through an opening in the adhesive layer or through a common opening in the second layer of polysiloxane and the adhesive layer that bonds the second layer of polysiloxane to the skin underneath. The layer structure illustrated by Figs. 1 and 2 shows how the conductive path between the first portion 206 of the conductor area and the sensing area can be provided in an integrated format without additional external wiring arrangements or other complicated procedures during manufacturing. It is noted that the format and pattern shown in Fig. 2 are merely exemplary. A wide variety of electrode and conductor formats may be applied in the pattern of conductors.

[0027] Figure 3 illustrates the steps of the method for creating a layered structure for an adhesive skin patch as described by Figures 1C and 2. Additional details for the explanation of Figure 3 may be referenced from Figures 1 and 2, and vice versa. Figure 3 is a schematic drawing presenting the steps and the sequence of those steps in a simplified form; the arrangement of the reels, the motors, and the mechanism for rolling the reels themselves are well known to those skilled in the art of printed electronics and will not be discussed in more detail herein.

[0028] In the method, the web to be worked on rests on a support layer carrier that is reeled for the process. Advantageously, the carrier is made of polyethylene terephthalate (PET), which is well suited for roll-to-roll reeling even at sub-millimeter thicknesses of the order of 0.01-0.5 millimeters, and provides a robust and protective base for the subsequent deposition steps. A layer of liquid soluble polymer is then deposited on the surface of the carrier (step 300). The liquid soluble polymer may be applied in liquid form on the surface of the carrier and may need to be cured before the subsequent deposition steps. Curing may include drying, heat treatment, chemical treatment, or the like.

[0029] In a next step, a first layer of polysiloxane is deposited on the layer of liquid soluble polymer (step 302). The polysiloxane may be, for example, a polydimethylsiloxane-based material. The first layer of polysiloxane comprises at least one opening, which requires that it is deposited in a patterned fashion. Advantageously, the patterning is achieved by masking the parts of the lower surface of the liquid soluble polymer that are not intended to be covered by the polysiloxane with a protective masking film, such as PET. The protective masking film is typically removed before the polysiloxane is cured for the next deposition step. Other methods for patterning, such as slot-die coating or screen printing, may be applied without departing from the scope of protection.

[0030] In the next step, a conductive layer pattern comprising conductor and sensing regions is deposited on the first layer of polysiloxane (step 304). It should be noted that FIG. 3 is schematic. Depending on the patterning method and materials selected, the deposition step 304 may be realized in one process step or it may comprise two or more sub-steps, for example a sub-step for depositing the conductor regions with one material and another sub-step for depositing the sensing regions with another material. Advantageously, the conductor regions are made of a highly conductive material, like copper or silver. The sensing regions may comprise a quantity or combination of materials whose electrical properties change as a function of the detectable changes on the skin of the subject. The sensing regions may alternatively comprise a structured combination of materials whose electrical properties are responsive to the detectable changes on the skin of the subject. There are many known methods for depositing conductive patterns on a moving sheet or web, for example screen printing, stencil printing. During deposition, the pattern of the conductive layer is positioned such that the conductor areas of the pattern are aligned to at least partially coincide with the openings in the first layer of polysiloxane, meaning that during deposition the deposited material at least partially fills the openings in the underlying first layer of polysiloxane.

[0031] In the next step, a second layer of polysiloxane is deposited on the conductive layer (step 306). Moreover, the second layer of polysiloxane includes at least one opening, so that the second layer needs to be deposited in a patterned fashion. Advantageously, the patterning is achieved by masking the parts of the lower surface of the liquid soluble polymer that are not intended to be covered by the polysiloxane with a protective masking film, such as PET or polyethylene (PE). The polysiloxane typically needs to be cured, and the protective masking film is preferably removed before the polysiloxane is cured for the next deposition step. As mentioned above, other methods for patterning, such as slot die coating, may be applied without departing from the scope of protection.

[0032] Finally, a layer of skin adhesive is deposited on the second layer of polysiloxane (step 308), further patterned to include openings that correspond to the sensing areas. The layer of skin adhesive can be deposited on the second layer of polysiloxane before the second layer of polysiloxane is deposited on the conductive layer, or the deposition can be accomplished as a separate step.

[0033] Roll-to-roll processing is a fabrication method used to manufacture products. In a roll-to-roll process, a web of material can be continuously fed from one reel onto another, and at the same time, material can be added to or removed from the advancing web to produce the desired product. By means of a defined layer structure, as illustrated by FIG. 3, a continuous stream of adhesive skin patches can be formed as an accumulated web in an industrial roll-to-roll process that proceeds sequentially through the layer deposition steps described herein. Since roll-to-roll processing requires a certain robustness in the reeled web, the double layer structure presented in FIG. 1C can be advantageous for such applications. By adjusting the process parameters (such as the speed of the web) and the material properties of the liquid soluble polymer 106, the processing method can be realized without step 301, i.e., starting by depositing a first layer of polysiloxane onto the film of liquid soluble polymer.

[0034] Alternatively, the layered structure can be industrially fabricated in a sequential sheet-to-sheet printing process, where the described deposition steps are performed progressively on a substrate sheet. As a more detailed implementation example, in a sheet-to-sheet process, a water-soluble polyvinyl alcohol (PVA) film can be formed on a PET carrier film by wire bar coating (step 300). A premixed two-component PDMS-based silicone elastomer is then deposited on a portion of the PVA film by wire bar coating (step 302). A portion of the PVA film is left exposed by masking the PVA film with a PET film, and the masking PET film is removed before curing the silicone elastomer. In the next step, a silver interconnect pattern is fabricated by screen printing partly on the silicone elastomer layer and partly on the exposed PVA layer (step 304). The portions of the silver interconnect pattern on the exposed PVA then form exposed pads for external electrical connection (when applied onto the skin). The silver interconnect pattern is then encapsulated by another layer of silicone elastomer by wire bar coating (step 306). Areas of the skin electrodes are left exposed by masking the silicone elastomer layer with a sheet of protective polyethylene (PE) liner (with low tack adhesive) film before wire bar coating and removing the mask film before curing. Silver / silver chloride (Ag / AgCl) skin electrodes are then fabricated on the exposed interconnects (step 304). A silicone-based two-component skin adhesive is then deposited by wire bar coating (step 308). The silver / silver chloride skin electrodes are masked by a protective polyethylene (PE) liner film that is removed after coating. Optionally, especially in commercial production, a protective film can be laminated onto the skin adhesive layer in the same process.

[0035] Figure 4 includes three images showing an exemplary skin patch formed by the layered structure described by Figures 1 and 2. The examples show how well the ultra-thin skin patch conforms to the skin even under stress ((i) compression, (ii) torsion, (iii) stretching).

[0036] FIG. 5 illustrates an advantageous use case for an adhesive skin patch formed by the layer structure described herein. FIG. 5 shows two exemplary skin patch articles 500, 502, which are described in more detail by FIG. 2. Each of these skin patches 500, 502 includes a skin electrode 504, 506 formed from a sensing region of a conductive layer in the layer stack. Each of these skin patches 500, 502 further includes an external contact 508, 510 and a conductive path 512, 514 that electrically connects the external contact to the skin electrode. The external contact and the conductive path are further formed from a conductive region of the conductive layer in the layer stack. FIG. 5 further shows an intervening unit 504, a separate electrical device that can be connected to the external connection of the skin patch 500, 502. The intervening element 504 can be a more complex device that includes electrical components configured to process, store, and / or output information based on signals derived from the skin electrodes. The arrangement results in a very compact setup, for example for electrocardiogram (ECG) monitoring.

[0037] In the earlier described examples, the conductor comprises a conductive layer 110 between the first layer 108 of polysiloxane and the adhesive layer 114 or between the first layer 108 of polysiloxane and the second layer 112 of polysiloxane. The sensing area 118 of the conductive layer 110 is then open to skin contact and the conductive area 116 is open directly to external contact through a recess 120 in the first layer 108 of polysiloxane. However, the skin patch may also be a multi-layer structure including one or more conductors, each of which may be separated from the other conductors by at least one layer of polysiloxane and thus electrically isolated. The conductors may be electrically connected by vias extending through one or more intermediate layers of polysiloxane. The vias may extend through one separate layer of polysiloxane, or the vias may extend through two or more intermediate layers of polysiloxane to interconnect two conductive layers. The vias may, in some configurations, extend through one or more conductive layer patterns, thus interconnecting three or more conductive layers.

[0038] 6A to 6C illustrate layers of an on-skin portion 600 in an exemplary multi-layer stack for a skin patch. Elements corresponding to each other in FIGS. 1A to 1C and 6A to 6C are indicated by similar reference numbers, and additional descriptions for those elements may be referred to from the descriptions of FIGS. 1A to 1C. The on-skin portion 600 of FIG. 6A corresponds to the embodiment of FIG. 1C and includes a first layer 608 of polysiloxane, a first conductor in the form of a first conductive layer 610, a second layer 612 of polysiloxane, and an adhesive layer 614. The first conductive layer 610 is formed into a pattern including a conductor region 616 and a sensing region 618 in electrical connection with the conductor region 616. However, in the examples that follow, the on-skin portion of the multi-layer structure includes an additional layer between the first layer 608 of polysiloxane and the first conductive layer 610 of the first connector. Further layers in the example of FIG. 6A include a third layer 652 of polysiloxane and a second conductive layer 650, which are deposited on the first layer 608 of polysiloxane before the deposition of the first conductive layer 610, in the order shown in FIG. 6A. The second conductive layer 650 is patterned into the form of at least one conductor. The first conductor is provided in the form of the first conductive layer 610 and includes a sensing area 618 and a conductor area 616. In use, the sensing area 618 is in contact with the skin through an opening 622 in the second layer 612 of polysiloxane and an opening 624 in the adhesive layer 614. However, now the opening 620 in the first layer 608 of polysiloxane opens to a second conductor provided by the second conductive layer 650, not directly to the conductor area 616 of the first conductive layer 610. This second conductor is electrically connected to a conductor region 616 in the first conductive layer 610 by means of a via 658. The signal generated on the skin is then accessible through the second conductive layer 650.

[0039] In the manufacturing process, the via between two conductive layers is first formed by patterning a recess in the intermediate layer or layers of polysiloxane between the conductive layers. When the conductive layer is deposited over the recess, the recess becomes filled with the fluid conductive material of the conductive layer, forming the via after curing. In the example of FIG. 6A, the via 658 is formed by patterning a recess that extends through the third layer 652 of polysiloxane. The third layer 652 of polysiloxane is patterned in this example such that a recess for the via 658 extends through the third layer 652 of polysiloxane, and when the conductor region 616 of the first conductive layer 610 is deposited, the fluid conductive material fills the recess and the via 658 is formed.

[0040] Thus, in the example of FIG. 6A, the first conductor is provided by the first conductive layer 610 and the second conductor is provided by the second conductive layer 650. Vias 658 electrically connect the first and second conductors. Thus, a signal generated through the skin contact of the first conductor (through the sensing area 618 of the first conductive layer 610) can be accessed through the second conductor (access to the conductive layer 650 through the opening 620 in the first layer of polysiloxane 608). Alternatively, an electrical signal can be sent onto the skin through the second conductor.

[0041] The example of Figure 6B illustrates a further option, where the further layers between the first layer of polysiloxane 608 and the first conductive layer 610 include the second conductive layer 650 described by Figure 6A, the third layer of polysiloxane 652, and further the third conductive layer 654 and the fourth layer of polysiloxane 656. These layers are deposited on the first layer of polysiloxane before the first conductive layer 610 and in the order shown in Figure 6B.

[0042] In the example of FIG. 6B, the second conductive layer 650 is formed into a pattern including two separate layer portions 650-1 and 650-2. These portions 650-1 and 650-2 are electrically isolated by the deposition of the third layer 652 of polysiloxane, thus forming two separate conductors. The third conductor may then be provided by the second portion 650-2 of the second conductive layer 650. The fourth conductor may then be provided by the third conductive layer 654, which includes a sensing region 670 and a conductor region 672. The sensing region 670 of the third conductive layer 654 is exposed to the skin through openings in the adhesive layer 614, the second layer 612 of polysiloxane, and the fourth layer 656 of polysiloxane. Due to the multi-layer structure, the adhesive patch may then include skin electrodes at various locations within the overall surface area of ​​the patch. 6B, the conductor area 672 of the third conductive layer 654 may be separately connected to the portion 650-2 of the second conductive layer 650 by means of a via 658. Thus, the signal generated through the skin contact of the fourth conductor (through the sensing area 670 of the third conductive layer 654) may be externally accessed through the third conductor (access to the portion 650-2 through an opening 678 in the first layer of polysiloxane 608). Alternatively, the electrical signal may be input through the third conductor and delivered onto the skin through the fourth conductor.

[0043] Figure 6C illustrates an example that corresponds to that of Figure 1A in that the adhesive layer 614 is patterned to include an opening 624 for the sensing region 618 of the first conductive layer 610, and the structure does not include the second layer of polysiloxane 612 shown in Figure 1C or Figures 6A and 6B. In the layers below the first conductive layer 610, the stack includes the layers described by the example of Figure 6B.

[0044] As discussed, the vias can extend through the layers of polysiloxane without crossing. This means that the stack described can provide various combinations of input and output interfaces at freely selected locations in the skin patch. The multi-layer format allows for high-density packaging of electronics and thus more complex circuits and operating functions. Due to the inventive use of fluids that can fill recesses in the earlier cured format and can even be patterned and cured to form recesses, the overall structure still remains extremely thin even when stacked into a multi-layer format. Thus, when the patch is glued onto the skin, it conforms to the wrinkles, contours and elastic movements of the skin, thereby minimizing the disturbance caused by the measurement realized by the skin patch.

[0045] 6A-6C, the conductor provided by the conductive layer is a pattern that does not necessarily cover the entire surface area underneath. In the figures, unnumbered boxes within the layer stack illustrate quantities of polysiloxane or adhesive material that fill at least a portion of the areas of the conductive layer that are not covered by the underlying pattern due to the wet stage of the deposition process.

[0046] Figures 7A and 7B illustrate further examples of on-skin portions 700 in a multi-layer stack for a skin patch. Elements corresponding to each other in Figures 1A to 1C, 6A to 6C, and 7A to 7B are indicated by similar reference numerals, and additional descriptions for those elements may be referenced from the descriptions of Figures 1A to 1C and 6A to 6C.

[0047] The example of Fig. 7A corresponds to the example described by Fig. 6B. As in Fig. 6B, the on-skin portion 700 includes a first layer 708 of polysiloxane, a first conductor provided by a first conductive layer 710, a second layer 712 of polysiloxane, and an adhesive layer 714. The first conductive layer 710 is formed into a pattern including a conductor region 716 and a sensing region 718 in electrical connection with the conductor region 716. Furthermore, in this example, further layers of the multilayer structure include a second conductive layer 750, a third layer 752 of polysiloxane, and a fourth layer 756 of polysiloxane, in the order shown in Fig. 7A. The second conductive layer 750 is also patterned into the form of two separate layer portions 750-1 and 750-2 of conductive material. These portions 750-1 and 750-2 are made in an electrically isolated manner by the deposition of a third layer 752 of polysiloxane, thus forming two separate conductors, the second conductor and the third conductor.

[0048] However, this time the fourth conductor is provided by two overlapping conductive layers, a third conductive layer 780 and a fourth conductive layer 782. The third conductive layer 780 provides the conductor area of ​​the fourth conductor and the fourth conductive layer 782 provides the sensing area of ​​the fourth conductor. The third conductive layer 780 is deposited as a pattern on the third layer 752 of polysiloxane and the fourth conductive layer 782 is deposited as a pattern on the third conductive layer 780. The fourth layer 756 of polysiloxane is deposited on top of the third conductive layer 780 and the fourth conductive layer 782 fills the void spaces in the underlying third and fourth conductive layers 780, 782 during its wet deposition stage. The third layer 754 and the fourth layer 756 of polysiloxane are patterned to include recesses for vias 758, which will be filled with conductive material during the deposition of the conductor regions 716 of the first conductive layer 710. The third layer 754 of polysiloxane is further patterned to include recesses for vias 774, which will be filled with conductive material during the deposition of the third conductive layer 780. The second layer 712 and the fourth layer 756 of polysiloxane, and the adhesive layer 714, which are deposited after the fourth conductive layer 782, are patterned to include recesses that provide openings for at least a portion of the conductive layer 782 of the fourth conductor.

[0049] Thus, in the example of FIG. 7A, the signal generated through the skin contact of the first conductor (through the sensing area 718 of the first conductive layer 710) can be externally accessed through the second conductor (access to portion 750-1 through the opening 720 in the first layer of polysiloxane 708). Alternatively, an electrical signal can be input through the second conductor and sent onto the skin through the first conductor. The third conductor is provided by the second portion 750-2 of the second conductive layer 750, and the fourth conductor is provided by the combination of the third conductive layer 780 and the fourth conductive layer 782. The signal generated through the skin contact of the fourth conductor (through the sensing area provided by the third conductive layer 782) can be externally accessed through the third conductor (access to portion 750-2 through the opening 778 in the first layer of polysiloxane 708). Alternatively, the electrical signal may be input through a third conductor and transmitted onto the skin through a fourth conductor.

[0050] 7A, the fourth layer of polysiloxane 756, the second layer of polysiloxane 712, and the adhesive layer 714 are formed on top of the third layer of polysiloxane 752, exposing the sensing area 782 of the fourth conductor where it is surrounded by the adhesive layer, which means that a firm connection to the skin around the third connector 780 is ensured.

[0051] Figure 7B illustrates an example that corresponds to the examples of Figure 1A or 6C in that the structure does not include the second layer of polysiloxane 712 shown in Figure 7A. Below the first conductive layer 710, the stack includes the layers described by the example of Figure 7A.

[0052] The examples described herein are schematic and non-limiting illustrations of elements and terms necessary to disclose the present invention. For example, the conductive layer that in some examples provides both the sensing area and the conductor area may be replaced by two conductive layers, one conductive layer providing the sensing area and the other conductive layer providing the conductor area, and vice versa. The example stacks in Figures 6A to 6C and 7A to 7C show stacks with and without a second layer of polysiloxane, but one or more additional layers of polysiloxane or other suitable materials may equally well be included in the stack. It is clear to those skilled in the art that the described structures and deposition steps have various possible implementation options that are not explicitly shown here but are encompassed by the scope of the appended claims.

Claims

1. 1. An adhesive skin patch comprising a first layer of polysiloxane, a first conductor, and an adhesive layer, the first conductor includes a conductor region and a sensing region in electrical communication with the conductor region; the first layer of polysiloxane comprises openings for at least a portion of the conductor area of ​​the first conductor or for a further conductive layer electrically connected to the conductor area of ​​the first conductor by one or more vias; The adhesive layer includes an opening for at least a portion of the sensing area of ​​the first conductor.

2. 10. The adhesive skin patch of claim 1, wherein the first conductor is a conductor layer formed into a pattern including the conductor region and the sensing region.

3. 3. The adhesive skin patch of claim 1 or 2, wherein the polysiloxane comprises polydimethylsiloxane.

4. 3. The adhesive skin patch of claim 1 or 2, wherein the portion of the conductor region of the first conductor is configured to provide a contact for electrical connection with the sensing region.

5. the adhesive skin patch includes a second layer of polysiloxane between the first conductor and the adhesive layer; The adhesive layer and the second layer of polysiloxane include a common opening for at least a portion of the sensing area.

3. An adhesive skin patch according to claim 1 or 2, characterized in that

6. 6. The adhesive skin patch of claim 5, wherein in the area beyond the opening, the first layer of polysiloxane and the second layer of polysiloxane surround the first conductor in a watertight manner.

7. the adhesive skin patch comprises one or more additional conductors, each conductor separated from another conductor by one or more intermediate layers of polysiloxane; The conductors of the adhesive skin patch are electrically connected by vias that extend through one or more intermediate layers of polysiloxane.

3. An adhesive skin patch according to claim 1 or 2, characterized in that

8. 8. The adhesive skin patch of claim 7, wherein at least one of the vias passes through two or more intermediate layers of polysiloxane to interconnect two conductors.

9. 3. An adhesive skin patch according to claim 1 or 2, characterized in that the skin patch comprises a releasable portion.

10. 10. The adhesive skin patch of claim 9, wherein the releasable portion comprises a layer of a liquid soluble polymer.

11. 11. The adhesive skin patch of claim 10, wherein the liquid soluble polymer is soluble in water.

12. 1. A method for creating a layer structure for an adhesive skin patch, comprising: depositing a first layer of polysiloxane onto the layer of liquid soluble polymer, the first layer being patterned to contain openings and cured to act as an elastic solid; depositing on the first layer of polysiloxane a first conductor including a conductor region and a sensing region in electrical connection with the conductor region, or depositing on the first layer of polysiloxane a second conductor, at least one intermediate layer of polysiloxane, and a first conductor including a conductor region and a sensing region, wherein the conductor region of the first conductor or the second conductor is aligned to at least partially coincide with the opening in the first layer of polysiloxane; depositing a layer of skin adhesive over the first conductor, the layer being patterned to include an opening that coincides with the sensing area of ​​the first conductor; A method comprising:

13. 13. The method of claim 12, wherein the first conductor is provided as a conductive layer formed into a pattern including the conductor region and the sensing region.

14. 14. The method of claim 12 or 13, characterized in that a second layer of polysiloxane is deposited on the first conductor, the second layer being patterned to include an opening that coincides with the opening patterned for the layer of skin adhesive and coincides with the sensing area.

15. 14. A method according to claim 12 or 13, characterized in that said layer of liquid soluble polymer is initially deposited on the surface of a sheet of supporting substrate.

16. 14. The method according to claim 12 or 13, characterized in that the layer structure is created in a roll-to-roll process, the layer structure being formed from a web of the roll-to-roll process progressing sequentially through the deposition stages.

17. 14. A method according to claim 12 or 13, characterized in that the layer structure is created in a sheet-to-sheet printing process, the layer structure being formed on a supporting substrate sheet which is processed in a progressive sequence through the deposition stages.

18. 14. The method according to claim 12 or 13, characterized in that the deposition of the first conductor is carried out in two parts, the conductor area being deposited before the deposition of the second layer of polysiloxane and the sensing area being deposited into the opening in the second layer of polysiloxane before or after the deposition of the second layer of polysiloxane.

19. depositing said second conductor in the form of a second conductive layer; depositing one or more intermediate layers of polysiloxane on the second conductive layer; patterning the one or more intermediate layers of polysiloxane with recesses; depositing the first conductor such that the recess is filled with a conductive material, thereby forming a via electrically connecting the first conductor to the second conductor. The method according to claim 12, characterized in that

20. depositing the second conductor as part of a second conductive layer comprising the second conductor and a third conductor; depositing a fourth conductor on at least one of said intermediate layers of polysiloxane, said fourth conductor including a conductor region and a sensing region in electrical communication with said conductor region; patterning an intermediate layer of polysiloxane between the third conductor and the fourth conductor with recesses; depositing the fourth conductor such that the recess is filled with a conductive material, thereby forming a via electrically connecting the third conductor to the fourth conductor.

20. The adhesive skin patch of claim 19,

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