Improved electronic device suitable for skin contact

Abstract

The invention provides, amongst other aspects, an electronic device suitable for skin contact, the electronic device comprising: a layer stack comprising an electrically insulating path and an electrically conducting path stacked atop the electrically insulating path; and a skin adhesive layer stacked atop the layer stack and the transfer layer, wherein the electrically conducting path comprises a skin-facing zone configured to be facing the skin, wherein the skin adhesive layer comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin.

Description

Improved electronic device suitable for skin contactField of the invention

[0001] The present invention relates to the technical domain of medical wearables, particularly to an improved electronic device suitable for skin contact.Background art

[0002] With the advent of printed electronics, new possibilities have been achievable in the technical domain of medical solutions, particularly that of medical monitoring solutions. The monitoring of a person’s health and body conditions can provide useful preventive and accurate information. These conditions can be measured through smart patches, smart textiles or other wearables that also need to be flexible and comfortable to the wearer or user.

[0003] Electronic skin patches and diagnostic electrodes are becoming increasingly important in the medical world. They enable remote and continuous monitoring of a patient’s health condition. Typical monitoring solutions include multilayer disposable patches with integrated electrodes for a wide range of applications, including ECG, EEG and EMG monitoring, skin conductivity (GSR) measurement or even electrostimulation. Such multilayer disposable patches rely on a Polyurethane (PU) or a Thermoplastic PU (TPU) substrate, therefore this involves a PU or a TPU applied as a layer to a carrier, a hard plastic. However, with PU-based patches and the TPU-based patches, the carrier is removed during production and discarded (i.e., single use). Other patches rely on polyester as a substrate, where a transfer tape and / or an overlay layer is used. However, polyester-based patches, as well as PU-based patches and TPU-based patches, are complex to fabricate and require a lot of work to put together. Furthermore, they suffer from breathability issues and are typically uncomfortable to the wearer or user. The PU or TPU layer typically also comprises sublayers according to a hot-melt principle, with a PU or a TPU sublayer with higher and a PU or a TPU sublayer with lower melting point, with the latter layer being melted between non-woven and PU or TPU at production. However, similar issues, including, complex fabrication, breathability issues and comfort issues, also arise.

[0004] Thus, there is a need for material combinations which are simpler to fabricate and produce less waste, while ensuring maximal ease of use and wearing comfort.

[0005] The present invention aims at addressing issues, such as the issues mentioned above.Summary of the invention

[0006] According to a first aspect, the invention provides a process for fabricating at least one electronic device according to the present invention, the process comprising: providing a transfer layer, forming a layer stack atop the transfer layer, forming a skin adhesive layer atop the layer stack and preferably the transfer layer, and separating the transfer layer from the layer stack and preferably the skin adhesive layer, wherein the step of forming a layer stack comprises: forming an electrically insulating path atop the transfer layer, andforming an electrically conducting path atop the electrically insulating path and preferably the transfer layer, wherein the skin adhesive layer comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin, preferably wherein a portion of the electrically conducting path relates to a skin-facing zone configured to be facing the skin.

[0007] In embodiments, an optional optimization is provided to enhance and / or to better preserve the adhesive strength of the skin adhesive. This is set out in the detailed description.

[0008] According to a second aspect, the present invention provides an electronic device suitable for skin contact, the electronic device comprising: a layer stack comprising an electrically insulating path and an electrically conducting path at least partially stacked atop the electrically insulating path; and a skin adhesive layer stacked atop the layer stack, wherein the skin adhesive layer comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin, preferably wherein a portion of the electrically conducting path relates to a skin-facing zone configured to be facing the skin.

[0009] By not including a substrate, such as TPU or polyester, the electronic device may advantageously be much thinner, which can therefore be more conformable when applied to the skin and more breathable. Moreover, avoiding a substrate (layer) in itself can also result in cost reduction. This may also allow for avoiding textile lamination, which can further reduce the cost and further make it possible to keep the electronic device thin.

[0010] Preferably, the electronic device comprises external interfacing means for connecting the electronic device to an external device. This can allow the monitoring of measurements measured by the electrically conducting path on the external device. Furthermore, this can allow the external device to transmit (electrical) signals to the conductive path, e.g., to calibrate, to control, to stimulate, to record, etc.

[0011] According to a third aspect, the invention provides a system comprising: an electronic device according to the present invention; and a connector for connecting the electronic device to the external device, preferably via the external interfacing means.

[0012] According to a fourth aspect, the invention offers a kit comprising: an electronic device according to the present invention, preferably a system according to the present invention; and a set of instructions and / or illustrations directing a user to adhere the electronic device onto the skin.

[0013] Preferred embodiments and their advantages are provided in the description and the dependent claims.

[0014] Further objectives, features and advantages of the electronic device according to the present invention will be apparent from the description below and the appended drawings. Objectives, features, and advantages of the process of fabrication described herein will also be apparent.Brief description of the drawings

[0015] The present invention will be discussed in more detail below, with reference to the attached drawings.

[0016] Fig. 1-3, 4A, 4B, 5A, and 5B each show an example electronic device according to the invention.

[0017] Thereby, Fig. 1-3 show an exploded view of an electronic device according to the invention. Furthermore, Fig. 4A and 5A show a longitudinal cross-section of an electronic device according to the invention, and Fig. 4B and 5B show a transversal cross-section of the respective electronic device according to the invention. Furthermore, Fig. 6A-6G show a top view of an electrically conducting path in an electronic device according to the present invention.Description of embodiments

[0018] The following descriptions depict only example embodiments and are not considered limiting in scope. Any reference herein to the disclosure is not intended to restrict or limit the disclosure to exact features of any one or more of the exemplary embodiments disclosed in the present specification.

[0019] 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. The terms are interchangeable under appropriate circumstances and the embodiments of the invention can operate in other sequences than described or illustrated herein.

[0020] Furthermore, the various embodiments, although referred to as “preferred” are to be construed as exemplary manners in which the invention may be implemented rather than as limiting the scope of the invention.

[0021] The term “comprising”, used in the claims, should not be interpreted as being restricted to the elements or steps listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising A and B” should not be limited to devices consisting only of components A and B, rather with respect to the present invention, the only enumerated components of the device are A and B, and further the claim should be interpreted as including equivalents of those components.

[0022] The term “stacked” refers to the arrangement of layers and / or paths on top of each other. The material of layers and / or paths may be deposited using various techniques such as 3D printing, inkjet printing, screen printing, gravure printing, transfer printing, sequential printing or laminating. Stacking may relate to filling holes and / or gaps in a path or layer, such as via-filling and / or through-hole filling. In this document, the paths and / or layers may not all have the same dimensions, particularly lengths and widths, thus, a path and / or layer may be stacked on multiple paths and / or layers. For example, if a first layer islonger than a second layer in a stacked configuration, it does not necessarily mean that the extended portion of the first layer is also stacked atop the second layer. The extended portion may therefore be stacked atop a third layer atop which the second layer is stacked, particularly atop a first portion of the third layer different from a second portion of the third layer atop which the second layer is stacked. Thus, if a first path or layer is stacked atop a second path or layer, 1 ) the first path or layer may be completely stacked atop the second path or layer (i.e., the bottom surface of the first layer is completely covered) because the first path or layer has equal dimensions (width and length) whereby the top surface of the second path or layer has been completely stacked (or covered), 2) the first path or layer may be completely stacked atop the second path or layer (i.e., the bottom surface of the first layer is completely covered) because the first path or layer has smaller dimensions (width and / or length) whereby the top surface of the second path or layer has been partially stacked (or covered), or 3) the first path or layer may be partially stacked atop the second path or layer (i.e., the bottom surface of the first layer is partially covered) because the first path or layer has equal dimensions (width and length) whereby the top surface of the second path or layer has been completely stacked (or covered),

[0023] In this document, the term "conforming" refers to suitability to conform closely to the body's contour. This may be a desirable property in the context of the invention, as it may improve the overall contact with the skin. This may have advantages relating to improved electronic contact between a portion of the device and the skin. However, in addition or alternatively, this may equally relate to improving the overall adherence and / or holding in place of the device with respect to the skin, which may relate to allowing a reduced use of adhesive (e.g., glue) and / or an improved ergonomics for the device and / or increasing the comfort of wearing the device over longer periods, e.g., an entire day, or several days, such as two days, three days, four days, five, days, six days, one week, or more. In embodiments, the device being conforming may relate to the device being "cohesive". Therein, the term "cohesive" may relate to the device being both conforming and allowing for retention and elasticity. In embodiments, the device may be adhering such that no adherence means other than adhesive are required, i.e., without the use of an extra closure.

[0024] The term "breathable" may refer to describe the ability of a material to allow the passage of air and / or moisture without causing damage to at least one of a path, a layer, the ink or the underlying encapsulant. In embodiments, the electronic device comprises a breathable coating or barrier layer in between the layer stack and the skin adhesive layer and / or in between the paths and / or layers comprised in the layer stack. By ensuring that the thickness of the breathable coating or barrier layer is smaller than that of any of the paths and / or layers, the overall breathability of the device can be increased. The breathable coating or barrier layer may comprise at least one from the insulating material group and / or at least one from the conductive material group. This can also help minimize the amount of ink required while maintaining electrical conductivity and / or insulation. In embodiments, at least one of the paths and / or layers in the layer stack (i.e., at least one of the electrically insulating layer, the further electrically insulating layer and the electrically conducting path (or layer)) and / or the skin adhesive layer comprises vents, such as (pin)holes or perforations. The vents may be strategically placed to help improve airflow and reduce moisture build-up underneath the electronic device and / or on a surface of any layer or path, particularly the (further) electrically insulating path or layer and / or the electrically conductive path or layer. In embodiments, the electrically conducting path comprises at least one of microflakes, microwires and microparticles (e.g.,silver microflakes), which can have inherently better breathability properties than traditional conductive inks. In embodiments, the skin adhesive layer may have a reduced thickness to increase breathability and flexibility of the skin adhesive layer. It may be advantageous to combine a thin skin adhesive layer on top the layer stack having vents in at least one path or layer therein. Examples of advantageous thicknesses of the skin adhesive layer are described herein.

[0025] The term “skin adhesive” relates to an adhesive material that is biocompatible and non-toxic. Preferably, the adhesive material may provide a comfortable and secure attachment of the electronic device to the skin. In embodiments, the skin adhesive material may comprise at least one from the adhesive group of: silicone, pressure-sensitive adhesive material, biodegradable adhesive material, water-soluble adhesive material, carbon-containing material. The silicone may comprise Polydimethylsiloxane (PDMS), liquid silicone, silicone gel. The pressure-sensitive adhesive material may comprise acrylic PSA, rubber PSA, silicone PSA, water-based PSA. The biodegradable adhesive material may comprise starch-based, cellulose-based, such as carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), Hydroxypropyl methylcellulose (HPMC), and Sodium carboxymethyl cellulose (NaCMC), Chitosan-based adhesive material. The water-soluble adhesive material may comprise HEC, CMC, NaCMC, HPMC, Polyvinyl alcohol (PVA), etc. The carbon-containing material may comprise at least one from the carbon group of: graphene, carbon nanotubes, and carbon black, etc. For example, the skin adhesive layer may comprise a carbon- loaded adhesive material.

[0026] The term “electrode” relates to an electrical component configured to allow contact between the human body (i.e., skin) and the electrically conducting path, particularly, the electrically conducting layer.

[0027] The term “path” relating to the terms “electrically conducting path” and “(further) electrically insulating path”, refers to a continuous structure or route between two points within the electronic device, particularly the layer stack. An electrically conducting path may relate to a continuous conductive material or structure, which can enable the flow of electrical current or signal from one point to another, e.g., from one component to another or from the electronic device to the skin and vice versa. An electrically insulating path may relate to a continuous insulating material or structure, which prevents the flow of electrical current or signals between two conductive elements or surfaces. The path may consist of a layer or may comprise the layer. Thus, the path is not limited to being a single layer and may extend along or comprise a plurality of layers.

[0028] The term “skin-facing zone” refers to a zone configured to be facing the skin, preferably allowing a portion of the electrically conducting path or a portion of the electrically conducting layer relating to said skin-facing zone to be in contact with the skin either directly or indirectly (e.g., via an electrode).

[0029] The term "encapsulant layer” relates to a protective coating or material which may be provided to a surface (e.g., to a surface of the layer stack, such as below the layer stack) or around a periphery of a component (e.g., around the periphery of the layer stack) to shield them from external factors that may cause damage or degradation.

[0030] The term “substrate” refers to a material or structure onto which various components, such as electrodes, sensing elements, and microelectronics are provided. A substrate provides mechanical support, electrical conductivity and biocompatibility for the components provided thereto. Typical materials used as substrates include, PET, PU or TPU. Prior art methods may rely on a multilayer TPU substrates comprisinga hotmelt layer (for thermal bonding) and a "hard" (typically, plastic such as TPU) layer used as carrier and removed during the production, wherein said hard layer is single use (not reusable). The invention may provide an alternative thereto by relying on substrates where layers removed during production may be reusable. In example prior art methods, a printed silver-containing ink may be provided over the multilayer PU or TPU substrate (Ag, something additionally relating to AgCI), followed by the provision of a hydrogel layer (or other layer with electrical conductivity relying on ion conduction) with limited shelf life, as the hydrogel properties may deteriorate rapidly over time (e.g., desiccation). The invention may provide an alternative thereto by avoiding such hydrogel, e.g., by relying on metal containing materials or on carbon- containing material, e.g., carbon-containing skin adhesive layer, as such material allows for regular (nonion-involving) conductivity. Furthermore, in prior art methods, a non-woven layer may be provided over a low temperature hotmelt layer of a multilayer PU or TPU substrate, followed by "ironing" (heating) to melt the hotmelt layer for obtaining an adherence between the non-woven layer and the PU or TPU substrate layer.

[0031] Prior art methods may involve a two-sided tape, wherein both sides of the liner are provided with an adhesive such as glue, and wherein the liner may relate, e.g., to two-sided tape. Such two-sided tape is complex in production and in handling, adding to the cost of goods as well as to the manufacturing process cost. This may be known for prior art methods and devices relying on polyester (PET), where device production may relate to providing layers on a two-sided transfer tape, typically followed by the providing of a form of backing, e.g., a non-woven backing or a foam backing. In contrast, the invention may allow to avoid such complex two-sided transfer tape by not relying on any means or substrate requiring adhesive on both sides.

[0032] In embodiments, an optional optimization is provided, i.e., an additional method step, as part of the manufacturing process, to enhance and / or to better preserve the adhesive strength of the skin adhesive. This may serve as preventive measure to handle cases of limited adhesion capacity of the skin adhesive, i.e., adhesion which may be found acceptable for some use cases but not sufficient for certain other use cases. Particularly, this may relate to an (example) process step wherein, following the printing of the ink, a layer of skin adhesive is laminated over it. Subsequently, the entire assembly is removed from the carrier, such that the ink is transferred onto the skin adhesive. In embodiments, in areas where no ink is present, the skin adhesive remains exposed and retains its tackiness, thereby enabling adhesion to the skin at a later stage. However, it has been observed that such a handling process can affect the adhesive strength of the skin adhesive. In simple terms, because the adhesive has already adhered to a surface once, its bonding strength may deteriorate, leading to limited skin adhesion strength. An optional optimization may be provided, as additional method step.

[0033] In some embodiments with optional optimization, the optional optimization involves the use of a masking film (a foil) with openings corresponding to the ink regions. This masking film is applied over the carrier bearing the ink and features cutouts at locations where ink is present. When the skin adhesive is laminated, it comes into contact only with the ink or the masking film. This masking film may, for example, be a release liner, thereby minimizing the impact on the adhesive properties of the skin adhesive. Accordingly, in embodiments, the process comprises the further step of providing a masking film with a geometry comprising openings corresponding to ink regions; applying the masking film over the formedlayer stack; wherein the geometry of the masking film is such that at least 80% of the skin adhesive layer, preferably essentially the entire skin adhesive layer, touches either the layer stack or the masking film and not the transfer layer. Thereby, in embodiments, at least part of, preferably all of, the masking film relates to a release liner of the skin adhesive layer.

[0034] In embodiments, the process comprises the step of providing a release linerover the skin adhesive; alternatively, the release liner may be provided over the skin adhesive already. In some embodiments with optional optimization, the optional optimization relates to partial removal (instead of full removal) of the release liner of the skin adhesive. The partial removal may thereby relate to the release liner being pre-cut (e.g., by kiss-cutting using a laser or die-cutting), whereby only the segments corresponding to the ink zones are removed. The skin adhesive, with its partially intact release liner (now featuring openings), may then be laminated onto the ink-bearing film. In this manner, the ink may be selectively transferred onto the skin adhesive, with reduced impact on the adhesive performance due to minimal pre-exposure. Accordingly, in embodiments, the skin adhesive layer is provided with a release liner, and the process further comprises: partially removing, from the release liner of the skin adhesive layer, segments corresponding to layer stack zones; wherein the steps of forming the skin adhesive layer atop the layer stack and the transfer layer and separating the transfer layer therefrom relates to selectively transferring the layer stack onto the skin adhesive layer. Thereby, in embodiments, the partial removal relates to the release liner being pre-cut. In embodiments, the being pre-cut relates to kiss-cutting. In embodiments, the kiss-cutting relates to using a laser and / or to die-cutting.

[0035] In embodiments, the skin adhesive layer is a conformal layer. The conformal skin adhesive layer may cover the steps, corners and curves of the layer stack in a substantially uniform manner (as shown in the embodiment of Fig. 4A-4C and 5A-5C). In embodiments, the skin adhesive layer serves as an insulator to the (external) contours of the electrically conductive path. Thus, the skin adhesive layer can prevent any loss of conductivity to the outside of the electronic device, e.g., when touched by a naked hand,

[0036] In embodiments, the electronic device extends longitudinally, wherein the paths and / or layers comprised in the electronic device, such as the layer stack (i.e., any or each of the paths, preferably layers, comprised therein) and the skin adhesive layer extend longitudinally and are stacked transversely.

[0037] In embodiments, the electronic device, preferably the electrically conducting path, further comprises external interfacing means configured for connecting the electronic device, preferably the electrically conducting path, to an external device. In embodiments, the external interfacing means relate to a snap button. In embodiments, external interfacing means other than a snap button may be provided, either in addition to or instead of a snap button. This may relate to external interfacing means such as one or more of any of a ZIF (zero insertion force) connector and / or a pogo pin (or, equivalently, a spring-loaded pin) and / or an alligator clip (or, equivalently, a crocodile clip). The snap button may comprise a top part and a bottom part, wherein the top part and the bottom part can connect / mate with each other.

[0038] In embodiments, the electronic device comprises a release layer atop of which the layer stack is stacked, preferably, atop of which the skin adhesive layer is further stacked. The release layer may be a release liner, e.g., a thin film. In embodiments, the release layer relates to the transfer layer atop of which the layer stack and / or the skin adhesive layer is / are stacked. The release layer can protect the layer stack, particularly the electrically conducting path, more particularly the portion of the electrically conducting pathwhich relates to the skin-facing zone, from degradation (e.g., due to oxidation, corrosion, temperature fluctuations, humidity, UV radiation, mechanical stress, chemical reactions, etc.). The release layer can protect the skin adhesive layer and / or electrode from dust and / or contamination caused by external factors, such as sticking to other surfaces before the electronic device is applied to its intended surface, i.e., skin. The release layer acts as a protective cover for the adhesive, allowing it to be easily separated or "released" when needed. Once the release layer is peeled off, the self-adhesive electronic device can be applied to its desired surface.

[0039] In embodiments, the external interfacing means may extend transversely towards and through the skin adhesive layer or an opening (e.g., aperture or annulus) therein, preferably from and through the release layer or an opening therein, more preferably through the layer stack or an opening in each of the path and / or layer therein, most preferably from the electrically conductive path.

[0040] In embodiments, a size (e.g. diameter, sides, width, length, etc.) of the opening in the skin adhesive layer may be larger than that of the external interfacing means to allow the external interfacing means to easily extend therethrough and / or to allow access to the external interfacing means. Preferably, the opening in the skin adhesive layer may be laser-cut or die-cut, such as in a cross-shape, to allow the external interfacing means to extend therethrough. This may be advantageous allowing for more adhesive surface area between the skin adhesive layer and the layer stack A size of the opening in the layer stack or in each path and / or layer therein, preferably in the electrically insulating path or layer and / or the further electrically insulating path or layer, may be smaller than that of the largest part of the external interfacing means, such as the base of, e.g. snap button, and larger than the smallest part of the external interfacing means, such as the head of, e.g. snap button. A size of the opening in the electrically conducting layer may be laser-cut or die-cut, such as in a cross-shape, to allow the external interfacing means to extend therethrough, while electrically connecting thereto. This may be advantageous allowing for a better electrical conductivity between the electrically conducting path and the external interfacing means. A size of the opening in the release layer may be larger than that of the external interfacing means.

[0041] In embodiments, the external interfacing means is electrically connected to the electrically conducting path. The external interfacing means may extend transversely towards and through the skin adhesive layer, preferably through an opening in the skin adhesive layer, more preferably further through the release layer or an opening therein. In preferred embodiments, the external interfacing means is electrically connected to another portion of the electrically conducting path other than the portion relating to the skin-facing zone. In embodiments, the skin-facing zone is at one end of the electrically conducting path and the external interfacing means is electrically connected to another end, e.g., an opposite end of the electrically conducting path. It would be more advantageous to keep the external interfacing means close enough to the skin-facing zone, thereby reducing the length of the electrically conducting path, and thus, reducing any loss of conductivity, e.g. due to dissipation.

[0042] In embodiments, the electrically conducting path is partially stacked atop the electrically insulating path, wherein the portion of the electrically conducting path relating to the skin-facing zone is configured to be facing the skin, preferably configured to be in contact with the skin. The portion of the electrically conducting path relating to the skin-facing zone may extend transversely, i.e., in a direction configured to be towards the skin. The portion of the electrically conducting path relating to the skin-facing zone mayextend longitudinally away from one end of the electrically insulating layer. The skin-facing zone and / or the portion of the electrically conducting path relating to the skin-facing zone may be surrounded by the electrically insulating layer, preferably tangentially surrounded.

[0043] In embodiments, the electrically insulating path consists of an electrically insulating layer. Alternatively, the electrically insulating path comprises the electrically insulating layer and an opening, such as an aperture or an annulus. The aperture (e.g., a hole in the electrically insulating path) may provide the skin-facing zone for the electrically conducting path. The annulus may relate to the space within a ring formed by the electrically insulating path and may provide the skin-facing zone for the electrically conducting path. In embodiments, the electrically insulating path comprises at least one electrically insulating layer and at least one opening, preferably a plurality of electrically insulating layers and respectively a plurality of openings.

[0044] In embodiments, the electrically conducting path consists of an electrically conducting layer. The portion of the electrically conducting path relating to the skin-facing zone may be a portion of the electrically conducting layer relating to the skin-facing zone. The portion of the electrically conducting path or layer may serve as an electrode. In such a case, the skin-facing zone may have enough contact with the skin, allowing the skin-facing zone and / or the portion of the electrically conducting layer relating to the skin-facing zone to contact the skin when adhered thereto. Alternatively, in embodiments, the electrically conducting path comprises at least one electrically conducting layer and at least one electrode, preferably a plurality of electrically conducting layers and respectively a plurality of electrodes. Preferably, the electrically conducting path comprises an electrically conducting layer and at least one of an electrode and an external interfacing means. The portion of the electrically conducting path relating to the skin-facing zone may be a portion of the electrically conducting layer relating to the skin-facing zone. The portion of the electrically conducting path or layer may be stacked atop the electrode and / or may relate to the skin-facing zone configured to be facing the skin. The electrode may be at least partially, preferably completely, comprised in the portion of the electrically conducting layer relating to the skin-facing zone. For instance, a first part of the electrode comprised in the portion of the electrically conducting layer relating to the skin-facing zone, and a second part of the electrode is stacked atop the electrically insulating layer. Preferably, the electrode may be completely comprised in the portion of the electrically conducting layer relating to the skin-facing zone, e.g., the electrode is not stacked atop the electrically insulating layer. In one example, the electrode is surrounded by the electrically insulating layer, preferably longitudinally surrounded. In another example, the electrode extends longitudinally away from one end of the electrically insulating layer. Thus, the electrode may be provided to fill in the gap to the skin created by the interference and / or the thickness of the electrically insulating layer. The electrically conducting layer may have any shape possible between one end and another end, such as between the skin-facing zone (or the portion relating thereto) and the external interfacing means (or the portion configured to be connected thereto).

[0045] In embodiments, the external interfacing means is electrically connected to the electrically conducting path. The external interfacing means may extend transversely towards and through the skin adhesive layer, preferably through an opening in the skin adhesive layer and / or further through the release layer or an opening therein. The external interfacing means may be via an opening in the skin adhesive layer, e.g., with a snap button. Alternatively, the external interfacing means may be accessible by bendingpart of the electronic device where the external interfacing means is connected to the electrically conducting path, while ensuring that the portion of the electrically conducting path relating to the skin-facing zone is in contact with the skin.

[0046] In embodiments, the external interfacing means is in another portion of the electrically conducting path other than the portion relating to the skin-facing zone. In embodiments, the skin-facing zone is at one end of the electrically conducting path and the external interfacing means is at another end, e.g., opposite end of the electrically conducting path. It would be more advantageous to keep the external interfacing means close enough to the skin-facing zone, thereby reducing the length of the electrically conducting path, and thus, reducing any loss of conductivity, e.g. due to dissipation.

[0047] In embodiments, the skin adhesive layer comprises the electrode, preferably, the electrode may be at least partially, preferably completely, located atop the portion of the electrically conducting path or atop the portion of the electrically conducting layer relating to the skin-facing zone. The electrode may be configured to indirectly allow the electrical connection between the skin and the electrically conducting path or layer. The electrode may be stacked atop the layer stack, particularly atop the electrically conducting path or layer, preferably atop the portion of the electrically conducting path or layer relating to the skinfacing zone.

[0048] In embodiments, the shape of the electrode is similar to a shape of the opening, such as aperture or annulus in the electrically insulating layer (i.e., of the inner contour of the aperture or annulus in the electrically insulating layer). The diameter or the sides of the electrode may be greater than or equal to the diameter or sides of the aperture or annulus in the electrically insulating layer (i.e., of the inner contour of the aperture or annulus in the electrically insulating layer). In embodiments, the shape of the electrode is similar to a shape of the portion of the electrically conducting path relating to the skin-facing zone. The diameter or the sides of the electrode may be greater than or equal to, preferably greater than, the diameter or sides of the portion of the electrically conducting path relating to the skin-facing zone. The larger the electrode, the more surface area may be configured to be in contact with the skin. Thus, the electrode can allow for improved electrical conductivity between the electrically conducting path and the skin.

[0049] In embodiments, the electrically conducting path comprises at least one from the conductive material group of: a metal-containing material, a conductive inorganic salt-containing material, a conductive polymer-containing material, etc. The choice of material may depend on the specific application, cost, availability, and printing technique used. The metal-containing material may comprise at least one from the metallic group of: aluminium, gold, copper, silver, iron, nickel, zinc, tin, lead, magnesium, cobalt, etc. The metal-containing material may comprise at least one of metallic microflakes, metallic microparticles and metallic microwires from the metallic group. Said at least one of metallic microflakes, metallic microparticles and metallic microwires can be dispersed in organic solvents or water-based solutions to form printable inks. The conductive inorganic salt-containing material may comprise at least one from the conductive inorganic salt group of: Silver Chloride (AgCI), Copper Sulfate (CuSO4), Nickel Oxide Hydroxide (Ni(OH)2), Iron Sulphide (FeS2 or FeS3), Cobalt Oxide (CoO or Co3O4), Manganese Dioxide (MnO2), Zinc Oxide (ZnO), etc. The conductive inorganic salt-containing material may comprise at least one cation from the metallic group in combination with at least one anion (e.g., chloride, sulfate, nitrate, bromide, iodide, oxide, etc.). The conductive polymer-containing material may comprise at least one from the conductive polymergroup of: Hydrogel, PEDOT (Polyaniline Derivatives), PPy (Polypyrole), and P3HT (Poly(3- hexylthiophene)), etc. The at least one from the conductive material group may be deposited using various printing techniques, such as inkjet, gravure, or screen printing.

[0050] In embodiments, the electrode comprises at least one from the conductive material group. In embodiments, the electrically conducting layer comprises at least one from the conductive material group. For example, the electrically conducting layer and the electrode (e.g., comprised in the electrically conducting path) both comprise the same conductive material (e.g., Ag or AgCI). In embodiments, the electrically conducting layer comprises at least one from the conductive material group and the electrode comprises at least one other from the conductive material group. For example, the electrically conducting layer comprises a conductive inorganic salt-containing material (e.g., AgCI) and the electrode (e.g., comprised in the skin adhesive layer) comprises a conductive polymer-containing material (e.g., hydrogel). In another example, the electrically conducting path comprises one metal-containing material (e.g., Ag) and the electrode comprises a carbon-containing material (e.g., a carbon-loaded skin adhesive layer).

[0051] In embodiments, the electrically insulating path comprises at least one from the insulating material group of: a thermosetting-containing material, an acrylic-containing material, a silicone-containing material, a ceramic-containing material, an organic-inorganic hybrid material, etc. The choice of material may depend on factors such as mechanical stability, flexibility, stretchability, required dielectric strength, thermal stability, chemical resistance, and processability. The electrically insulating path may relate to a dielectric path. The thermosetting-containing material may be a resin and / or may comprise at least one from the thermosetting resin group of: polyester, epoxy, polyimide, benzocyclobutene (BCB), etc. The thermosetting-containing material or resin can form a cross-linked structure upon curing. The acryliccontaining material may be a resin and / or may comprise at least one from the acrylic group of: Poly(methyl methacrylate) (PMMA), Poly(ethyl methacrylate) (PEMA), Poly(butyl methacrylate) (PBMA), Polystyreneacrylate (PSA), Acrylonitrile-butadiene-styrene (ABS), etc. The acrylic-containing material can offer moderate dielectric strength and low dissipation factor, making them suitable for applications where high electrical insulation is not required. The silicone-containing material may comprise at least one a silicone group of: polydimethylsiloxane (PDMS), polyvinylidene difluoride (PVDF), etc. The silicone-containing material can offer high dielectric strength and low dissipation factor, making them suitable for applications where high electrical insulation is essential. The ceramic-containing material may comprise at least one from the ceramic group of: barium titanate (BaTiO3), alumina (AI2O3), etc. The ceramic-containing material can offer extremely high dielectric strength, low dissipation factor, and excellent thermal stability, making them suitable for applications where the highest level of electrical insulation is required. The organic- inorganic hybrid material may comprise at least one from the hybrid group of: sol-gel derived silica, Organosilanes, Poly(urethane-isocyanate)s (PUIs), etc. The organic-inorganic hybrid material can offer a good balance between mechanical strength, thermal stability, and electrical properties. The organic- inorganic hybrid material can be more processable than traditional ceramic materials, allowing for greater design flexibility in the printing process. The at least one from the insulating material group may be deposited using various printing techniques, such as inkjet, gravure, or screen printing. The at least one from the insulating material may provide at least one of high mechanical stability, high mechanical flexibility, high mechanical stretchability, high dielectric strength, low dissipation factor, and good resistance tomoisture, chemicals, and temperature cycling. In embodiments, the electrically insulating layer comprises at least one from the insulating material group. In embodiments, the contour of the opening, such as aperture or annulus, comprises at least one from the insulating material group. In embodiments, the electrically insulating layer and the contour of the opening comprises the same at least one from the insulating material group.

[0052] In embodiments, the layer stack comprises a further electrically insulating path stacked atop the electrically conducting path. Thus, the electrically conducting path may be partially sandwiched between two electrically insulating paths or layers. Preferably, parts of the electrically conducting path, e.g., at least part of the electrically conducting layer and / or parts other than the skin-facing zone, may be sandwiched between two electrically insulating paths or layers. In embodiments, the further electrically insulating path comprises a further electrically insulating layer, preferably, consisting thereof. The further electrically insulating path may ensure that the electronic device has enough thickness on top of the electrically conducting path, particularly on top of the portion of the electrically conducting path relates to a skin-facing zone, to provide the required support and / or rigidity for said portion of the electrically conducting path (e.g., the electrode) to maintain consistent contact with the skin.

[0053] In embodiments, the further electrically insulating path or layer comprises at least one from the insulating material group. In embodiments, the electrically insulating path or layer comprises at least one from the insulating material group and the further electrically insulating path or layer comprises at least one other from the insulating material group. In alternative embodiments, both the electrically insulating path or layer and the further electrically insulating path or layer comprise the same at least one from the insulating material group.

[0054] In embodiments, the skin adhesive layer comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin. In preferred embodiments, the skin adhesive layer comprises a nonadhesive side having a backing material, which may be from the group of: non-woven, PU, TPU, polyester, urethane, textile, foam, etc. The adhesive layer, particularly the electrode comprised therein, may comprise a carbon-containing material (e.g., a carbon-loaded adhesive material) or conductive polymer-containing material (e.g., hydrogel).

[0055] In embodiments, the skin adhesive layer, particularly the adhesive side has a thickness of at most 75 microns, at most 50 microns, at most 45 microns, at most 40 microns, at most 35 microns, at most 30 microns, at most 25 microns. Thus, the adhesive side may have a thickness in the range of 10-75 microns. In embodiments, the non-adhesive side of the skin adhesive layer has a thickness of at most 150 microns, at most 100 microns, at most 90 microns, at most 80 microns, at most 70 microns, at most 60 microns, at most 50 microns, at most 45 microns, at most 40 microns, at most 35 microns, at most 30 microns, at most 25 microns. Thus, the non-adhesive side may have a thickness in the range of 10-150 microns The lower thicknesses can allow the electronic device to be more breathable, e.g. through inherent permeability or allowing to apply small opening or vents more easily, while a thicker adhesive layer can provide improved processing thereof (due to the improved handling thereof).

[0056] In embodiments, the electrically conducting path or layer has a thickness of at most 15 microns, at most 14 microns, at most 13 microns, at most 12 microns, at most 11 microns, at most 10 microns, at most5 microns. In embodiments, at least one of the electrically insulating path or layer and the further electrically insulating path or layer has a thickness of at most 20 microns, at most 18 microns, at most 16 microns, at most 14 microns, at most 12 microns, at most 10 microns, at most 5 microns. In embodiments, at least one, preferably each, of the electrically insulating path or layer and the further electrically insulating path or layer has a thickness of at most 20 microns, at most 18 microns, at most 16 microns, at most 14 microns, at most 12 microns, at most 10 microns, at most 5 microns. The thickness can allow the paths and / or layers to be more breathable, e.g. through inherent permeability or allowing to apply small opening or vents more easily. It will be understood that although each of the paths and / or layers may have the same thickness, it is preferable that each thereof has a respective thickness based on the needs of thereof. For example, for insulation and protection needs the electrically insulating path or layer may have a thickness larger than the electrically conductive path or layer. In embodiments, all paths or layers in the layer stack have similar thicknesses. In preferred embodiments, each of the electrically insulating path or layer and / or the further electrically insulating path or layer have a thickness which is greater than the thickness of the electrically conducting path or layer.

[0057] In embodiments, the release layer has a thickness of at most 250 microns, at most 200 microns, at most 150 microns, at most 100 microns, at most 50 microns.

[0058] In embodiments, the electronic device comprises a stiffening layer. The stiffening layer may be stacked atop the skin adhesive layer, preferably atop a portion of the skin adhesive layer relating to the external interfacing means, i.e., where the external interfacing means can be accessed, such as via an opening, slit or by bending the electronic device). For example, the external interfacing means is a snap button, extending through a slit in the skin adhesive layer, wherein the stiffening layer is stacked atop the skin adhesive layer, preferably atop a portion surrounding said opening or slit. The stiffening layer may be sandwiched between the top part of the snap button and the skin adhesive layer. In another example the external interfacing means is a ZIF connector, accessible by bending part of the electronic device where the ZIF connector is connected to the electrically conducting path, and the stiffening layer is stacked atop the portion of the skin adhesive layer which is stacked atop the ZIF connector. The stiffening layer may provide an additional thickness to the electronic device, particularly to provide a more rigid portion for allowing a user to connect the external interfacing means more robustly to the connector.

[0059] In embodiments, the stiffening layer has a thickness of at most 200 microns, at most 175 microns, at most 150 microns, at most 125 microns, at most 100 microns, at most 75 microns, at most 50 microns. Thus, the stiffening layer may have a thickness in the range of 20-200 microns. The stiffening layer may comprise an adhesive material, such as a skin adhesive material or another adhesive material.

[0060] In embodiments, the portion of the electrically conducting path relating to the skin-facing zone comprises a conductive material and a plurality of openings. The shape of the portion of the electrically conducting path relating to the skin-facing zone may be circular. Other shapes, such as polygonal (i.e., triangle, square, rectangle, pentagon, hexagon, etc.) can also be used. In preferred embodiments, the ratio of the openings to the conductive material is at least 1.5:1 , at least 2:1 , at least 3:1 , at least 4:1 , at least 5:1 , at least 6:1 , at least 7:1 , at least 8:1 , etc. Examples of different ratios are described with reference to Fig. 6A-6G. These particular ratios allow the conductive material to conduct enough electrical signals or current between the skin and the electrically conducting path (via the portion thereof relating to the skin-facing zone), while ensuring that the skin adhesive layer can still properly adhere to the skin. This ensures more flexible and comfortable adhesion of the electronics device to the skin, while more effectively conducting electrical signals or current. Thus, the need for an electrode, such as in the electrically conducting layer (e.g., dry electrode) or in the skin adhesive layer (e.g., hydrogel) is reduced, preferably removed.

[0061] In embodiments, the opening in at least one of the skin adhesive layer, the electrically conducting layer, the electrically insulating layer, the further electrically insulating layer and the release layer, relating to the external interfacing means (i.e., for allowing the extension of the external interfacing means therethrough or for allowing the access to the external interfacing means) may be a slit, such as a crossshaped slit, e.g. by means of a die cut, a laser cut, a perforation, etc. In preferred embodiments, the skin adhesive layer and the electrically conductive layer each comprises an opening relating to the slit.

[0062] In embodiments, the system comprises an electronic device according to the present invention, and a connector for connecting the electronic device to the external device, preferably via the external interfacing means. The connector may be connected to the external interfacing means. In embodiments, the connector provides a wired connection between the electronic device to the external device. Alternatively, the connector may provide a wireless connection between the electronic device and the external device. The connector may comprise a complementary connection to the external interfacing means, such as a socket for a snap button, or a ZIF connector having compatible pin arrangements that can connect / mate with the external interfacing means being a flat connection (e.g., cable), or pogo pins that can connect / mate with the external interfacing means being a pogo pad.

[0063] In embodiments, the connector comprises a transmitter for transmitting data, such as setting information and / or measurements, to the external device, particularly to a receiver end of the external device. In preferred embodiments, the connector comprises a receiver for receiving signals, such as control signals, preferably from a transmitter end of the external device. The control signals may relate to at least one of: providing a power supply to the electronic device, wireless protocols (e.g., Bluetooth, Wi-Fi, or Zigbee, which enable the sensor to transmit data to the external device directly or indirectly, e.g. via a server or cloud), trigger signals (e.g., electrical inputs that can be used to initiate a specific function in the electronic device), calibration signals (e.g., transmitting reference signals to enable the electronic device to accurately measure physical parameters), control parameters (e.g., adjustable parameters that allow the user to modify the behaviour of the electronic device) and software commands (e.g., instructions transmitted to the electronic device to modify settings and / or behaviour of the electronic device).

[0064] In embodiments, the system comprises the external device. The external device may comprise a display and / or a graphical user interface (GUI). The GUI may allow the user to visualize the received data from the electronic device, e.g. on the display of the external device. The GUI may allow the user to select and / or generate control signals to transmit to the electronic device. The external device may be a sever or a cloud server, a portable electronic device (e.g., laptop, smart phone, etc.), etc.

[0065] In embodiments, the system comprises a printed circuit board (PCB). The PCB may serve as the connector for providing a connection between the electronic device and the external device. The PCB may be a flexible PCB. The flexible PCB may still allow the electronic device to be flexible and comfortable to the user when applied to their skin compared to electronic devices where rigid connectors are used.

[0066] In embodiments, the kit comprises an electronic device according to the present invention, preferably a system according to the present invention; and a set of instructions and / or illustrations directing a user to adhere the electronic device onto the skin. Such instructions may be printed on the release layer (e.g. on the surface facing away from the layer stack and / or skin adhesive layer), on a package in which the electronic device or system is provided, on the skin adhesive layer (e.g., the surface facing away from the layer stack or configured to be facing away from the skin), or on a separate paper or booklet in the kit.

[0067] To inform the user regarding proper use of the electronic device, instructions in the form of written instructions and / or illustrations may be provided with a packaged electronic device. A kit can thus be provided comprising an electronic device according to the invention, a set of instructions for attaching or adhering the electronic device to the skin, and optionally, an outer package. The kit may further comprise the connector (i.e., comprised the system according to the present invention).

[0068] In embodiments, the process for fabricating at least one electronic device relates to a method for manufacturing the at least one electronic device.

[0069] In embodiments, the invention relates to providing one or more paths and / or layers over a substrate that is removed during production and may be reusable. This may relate to a hard plastic layer, although a wide range of materials may be suitable for this purpose. In embodiments, the substrate may thereby act as the transfer layer or foil.

[0070] In embodiments, a first step is providing a transfer layer or film atop of which the layer stack and the skin adhesive layer are stacked. A second step is forming the layer stack atop the transfer layer. The second step comprises forming the electrically insulating layer atop the transfer layer and forming the electrically conducting layer atop the electrically insulating layer and preferably the transfer layer. A third step is forming the skin adhesive layer atop the layer stack (i.e., on the top side of the layer stack facing away from the transfer layer) and preferably atop the transfer layer, wherein the skin adhesive layer comprises an adhesive side having the skin adhesive material, wherein a first portion of the adhesive side faces the layer stack (e.g., the electrically conducting path or the further insulating path), and a second portion of the adhesive side is configured to be facing the skin. The first step may be provided by applying a pre-existing transfer layer (e.g., a transferfilm that has already been used). The second may be performed by printing a respective material (e.g., ink). The third step may be performed, such as laminating, by applying a pre-existing skin adhesive layer.

[0071] In embodiments, the skin adhesive layer may be partially formed atop a portion of the transfer layer, particularly atop a portion of the transfer layer where the layer stack is not formed.

[0072] In preferred embodiments, a portion of the electrically conducting path relates to the skin-facing zone configured to be facing the skin.

[0073] In advantageous embodiments, the transfer layer is separated from the layer stack, and preferably from the skin adhesive layer. The transfer layer may thus be reused for fabricating or manufacturing further electronic devices. In embodiments, the process comprises forming a release layer at the bottom side of the layer stack after which the transfer layer has been separated from the formed layer, i.e. the layer stack and preferably the skin adhesive layer. The forming of the release layer may be performed by applying a pre-existing release layer. Alternatively, the transfer layer may act as the release layer. Thus, the transferlayer may be separated from the layer stack and / or the skin adhesive layer (e.g., released) when the electronic device is to be applied to the skin (e.g., adhered or attached).

[0074] In embodiments, the invention may relate to providing the external interfacing means in array before singularization into individual electronic devices. The singularization may relate to singularization means, e.g., to die cutting, lasering, perforating, snapping, etc. Thus, the process comprises a step of dividing the formed layers into at least two electronic devices after providing the external interfacing means. The formed layers may include the formed layer stack and the skin adhesive layer, preferably in addition to the release layer. In alternative embodiments, the invention may relate to providing the external interfacing means after singularization into individual electronic devices. Thus, the process comprises a step of dividing the formed layers into at least two electronic devices before providing the external interfacing means.

[0075] In embodiments, the forming of the release layer may be performed before providing the external interfacing means. Thus, the release layer may comprise openings to accommodate the external interfacing means therethrough. In alternative embodiments, the forming of the release layer may be performed after providing the external interfacing means. Thus, the release layer may comprise openings to accommodate the external interfacing means therethrough, preferably, the release layer completely covers the bottom side (i.e., configured to be skin facing) of the electronic device, including the external interfacing means.

[0076] In embodiments, the opening in at least one of the skin adhesive layer, the electrically conducting layer, the electrically insulating layer, the further electrically insulating layer, and the release layer, (i.e., for allowing the extension of the external interfacing means therethrough or for allowing the access to the external interfacing means), relating to the external interfacing means, may be provided during the step of singularization. Preferably, the opening in at least the skin adhesive layer and the electrically conducting layer relating to the external interfacing means may be provided during the step of singularization, particularly by the singularization means. For example, said opening(s) may be laser-cut or die-cut, such as in a cross-shape.

[0077] In a fifth aspect, there is provided a device set comprising a plurality of electronic devices according to the first aspect of the present invention, preferably a system set comprising a plurality of systems according to the second aspect of the present invention.

[0078] In embodiments, the device set comprises a plurality of attached electronic devices (i.e., not singularized).

[0079] In embodiments, the system set comprises a device set and a plurality of respective connectors for connecting the respective electronic device to the external device, preferably via the respective external interfacing means.

[0080] In embodiments, the process for fabricating at least one electronic device, preferably a plurality of electronic devices or at least one device set, more preferably a plurality of device sets according to the present invention, comprises: providing a (common) transfer layer, forming respective layer stacks of the plurality of electronic devices atop the transfer layer, forming respective skin adhesive layers of the plurality of electronic devices atop the respective layer stacks and the transfer layer, andseparating the transfer layer from the respective layer stacks and the respective skin adhesive layers, wherein the step of forming respective layer stacks comprises: forming respective electrically insulating paths atop the transfer layer, and forming respective electrically conducting paths atop the respective electrically insulating paths, wherein respective portions of the respective electrically conducting path relate to respective skinfacing zones (23a) configured to be facing the skin, wherein the respective skin adhesive layers comprise respective adhesive sides having a skin adhesive material, wherein respective first portions of the respective adhesive sides face the respective layer stacks, and respective second portions of the respective adhesive sides are configured to be facing the skin.Another electronic device

[0081] According to another first aspect, which is not limiting to the invention, there is provided an electronic device suitable for skin contact, the electronic device comprising: an encapsulant layer; a layer stack stacked atop the encapsulant layer, wherein the layer stack comprises an electrically conducting path; and a skin adhesive layer stacked atop the layer stack, wherein the skin adhesive layer comprises a first adhesive side having an adhesive material, wherein the first adhesive side faces away from the layer stack and is configured to be facing the skin, preferably wherein a portion of the electrically conducting path relates to a skin-facing zone configured to be facing the skin.

[0082] In preferred embodiments, the layer stack comprises an electrically insulating path stacked atop the electrically conducting path.

[0083] In embodiments, the skin adhesive layer comprises a second adhesive side having an adhesive material, wherein a first portion of the second adhesive side faces the layer stack, and a second portion of the second adhesive side faces the encapsulant layer. Preferably, the skin adhesive layer comprises an opening, such as aperture or an annulus, preferably in a portion of the skin adhesive layer relating to the skin-facing zone (e.g., atop of the portion of the electrically conducting path relating to the skin-facing zone). The aperture (e.g., a hole in the skin adhesive layer) may provide the skin-facing zone for the electrically conducting path. The annulus may relate to the space within a ring formed by the skin adhesive layer and may provide the skin-facing zone for the electrically conducting path.

[0084] In embodiments, the skin adhesive layer is a conformal layer. The conformal skin adhesive layer may cover the steps, corners and curves of the layer stack in a substantially uniform manner.

[0085] In embodiments, the encapsulant layer is a conformal layer. The conformal encapsulant layer may cover the steps, corners and curves of the layer stack in a substantially uniform manner. In embodiments, the encapsulant layer serves as an insulator to the (external) contours of the electrically conductive path.Thus, the encapsulant layer can prevent any loss of conductivity to the outside of the electronic device, e.g., when touched by a naked hand,

[0086] In embodiments, the electrically conducting path consists of an electrically conducting layer. The portion of the electrically conducting path relating to the skin-facing zone may be a portion of the electrically conducting layer relating to the skin-facing zone. The portion of the electrically conducting path or layer may serve as an electrode. In such a case, the skin-facing zone may have enough contact with the skin, allowing the skin-facing zone and / or the portion of the electrically conducting layer relating to the skin-facing zone to contact the skin when adhered thereto. Alternatively, in embodiments, the electrically conducting path comprises at least one electrically conducting layer and at least one electrode, preferably a plurality of electrically conducting layers and respectively a plurality of electrodes. The electrode may be partially comprised in the portion of the electrically conducting layer relating to the skin-facing zone. The electrode may be stacked atop the portion of the electrically conducting layer and / or may relate to the skin-facing zone configured to be facing the skin. For instance, a first part of the electrode comprised in the portion of the electrically conducting layer relating to the skin-facing zone, and a second part of the electrode atop of which the electrically insulating layer is stacked. Preferably, the electrode may be completely comprised in the portion of the electrically conducting layer relating to the skin-facing zone, e.g., the electrically insulating layer is not stacked atop the electrode. In one example, the electrode is surrounded by the electrically insulating layer, preferably tangentially surrounded. In another example, the electrode extends longitudinally away from one end of the electrically insulating layer. Thus, the electrode may be provided to fill in the gap to the skin created by the interference and / or the (combined) thickness of the skin adhesive layer and / or the electrically insulating path or layer. The electrically conducting layer may have any shape possible between one end and another end, such as between the skin-facing zone (or the portion relating thereto) and the external interfacing means (or the portion configured to be connected thereto).

[0087] In embodiments, the electrically conducting path comprises at least one electrically conducting layer and at least one electrode, preferably a plurality of electrically conducting layers and respectively a plurality of electrodes.

[0088] In embodiments, the electrically insulating path consists of an electrically insulating layer. Alternatively, the electrically insulating path comprises the electrically insulating layer and an opening, such as an aperture or an annulus. In embodiments, the electrically insulating path comprises at least one electrically insulating layer and at least one opening, preferably a plurality of electrically insulating layers and respectively a plurality of openings.

[0089] In embodiments, the electronic device, preferably the electrically conducting path, further comprises external interfacing means configured for connecting the electronic device, preferably the electrically conducting path, to an external device.

[0090] In embodiments, the external interfacing means relate to a snap button. In embodiments, external interfacing means other than a snap button may be provided, either in addition to or instead of a snap button. The external interfacing means may extend transversely towards and through the encapsulant layer, preferably through an opening in the encapsulant layer. The external interfacing means may be provided through a respective opening in at least one of the skin adhesive layer, the electrically insulating layer, and the electrically conductive layer (and electrically connected thereto).

[0091] In embodiments, the external interfacing means is electrically connected to the electrically conducting path. The external interfacing means may extend transversely towards and through the encapsulant layer, preferably through an opening in the encapsulant layer. The external interfacing means may be provided through a respective opening in at least one of the skin adhesive layer, the electrically insulating layer, the electrically conductive layer (and electrically connected thereto), and the release layer. In preferred embodiments, the skin-facing zone is in a first portion of the electrically conducting path and the external interfacing means is electrically connected to a second portion of the electrically conducting path. The first portion may include the one end of the electrically conducting path and the second portion may include the opposite end of the electrically conducting path. In highly preferred embodiments, the skinfacing zone is at one end of the electrically conducting path and the external interfacing means is electrically connected to an opposite end of the electrically conducting path. This can ensure that the external interfacing means is close enough to the skin-facing zone.

[0092] In embodiments, the external interfacing means may extend transversely from and through the skin adhesive layer, preferably towards and through an opening (e.g., aperture or annulus) in the skin adhesive layer, more preferably further towards and through the encapsulant layer or an opening therein, most preferably from the electrically conducting path.

[0093] In embodiments, a size (e.g. diameter, sides, width, length, etc.) of the opening in the skin adhesive layer may be larger than that of the external interfacing means to allow the external interfacing means to easily extend therethrough and / or to allow access to the external interfacing means. Preferably, the opening in the skin adhesive layer may be laser-cut or die-cut, such as in a cross-shape, to allow the external interfacing means to extend therethrough. This may be advantageous allowing for more adhesive surface area between the skin adhesive layer and the layer stack A size of the opening in the layer stack or in each path and / or layer therein, preferably in the electrically insulating path or layer and / or the further electrically insulating path or layer, may be smaller than that of the largest part of the external interfacing means, such as the base of, e.g. snap button, and larger than the smallest part of the external interfacing means, such as the head of, e.g. snap button. A size of the opening in the electrically conducting layer may be laser-cut or die-cut, such as in a cross-shape, to allow the external interfacing means to extend therethrough, while electrically connecting thereto. This may be advantageous allowing for a better electrical conductivity between the electrically conducting path and the external interfacing means. A size of the opening in the release layer may be larger than that of the external interfacing means. A size of the opening in the encapsulant layer may be larger than that of the external interfacing means to allow the external interfacing means to easily extend therethrough and / or to allow access to the external interfacing means. The opening in the encapsulant layer may be laser-cut or die-cut, such as in a cross-shape, to allow the external interfacing means to extend therethrough. The opening in the encapsulant layer may be a non-printed area in the encapsulant layer to allow the external interfacing means to easily extend therethrough and / or to allow access to the external interfacing means,

[0094] In embodiments, the external interfacing means is comprised in the electrically conducting path. The external interfacing means may extend transversely towards and through the encapsulant layer, preferably through an opening in the encapsulant layer. Optionally, the external interfacing means may further be provided through a respective opening in at least one of the skin adhesive layer, and theelectrically insulating layer. In embodiments, the skin-facing zone is in a first portion of the electrically conducting path and the external interfacing means is in a second portion of the electrically conducting path. The first portion may include the one end of the electrically conducting path and the second portion may include the opposite end of the electrically conducting path. In highly preferred embodiments, the skinfacing zone is at one end of the electrically conducting path and the external interfacing means is at an opposite end of the electrically conducting path.

[0095] In embodiments, the electrically conducting path comprises at least one from the conductive material group, as described herein with respect to the first aspect of the invention. For example, the electrically conducting layer and the electrode (e.g., comprised in the electrically conducting path) both comprise the same conductive material (e.g., Ag or AgCI). In embodiments, the electrode comprises at least one from the conductive material group. In embodiments, the electrically conducting layer comprises at least one from the conductive material group. In preferred embodiments, the electrically conducting layer comprises at least one from the conductive material group and the electrode comprises at least one other from the conductive material group. For example, the electrically conducting layer comprises a conductive inorganic salt-containing material (e.g., AgCI) and the electrode (e.g., comprised in the skin adhesive layer) comprises a conductive polymer-containing material (e.g., hydrogel). In another example, the electrically conducting path comprises one metal-containing material (e.g., Ag) and the electrode comprises a carbon- containing material (e.g., a carbon-loaded skin adhesive layer).

[0096] In embodiments, the electrically insulating path comprises at least one from the insulating material group, as described herein with respect to the first aspect of the invention. In embodiments, the electrically insulating layer comprises at least one from the insulating material group. In embodiments, the aperture or annulus comprises at least one from the insulating material group. In preferred embodiments, the electrically insulating layer and the aperture or annulus comprises the same at least one from the insulating material group.

[0097] The encapsulant may ensure that the electronic device has enough thickness below the electrically conducting path (i.e., configured to be facing away from the skin), particularly below the portion of the electrically conducting path which relates to a skin-facing zone, to provide the required support and / or rigidity for said portion of the electrically conducting path (e.g., the electrode) to maintain consistent contact with the skin. Additionally or alternatively, the layer stack may comprise a further electrically insulating path atop which the electrically conducting path is stacked. Thus, the electrically conducting path may be partially sandwiched between two electrically insulating paths or layers. In embodiments, parts of the electrically conducting path, e.g., at least part of the electrically conducting layer and / or parts other than the skin-facing zone, may be sandwiched between the electrically insulating path and the encapsulant layer or between the two electrically insulating paths or layers. In embodiments, the further electrically insulating path comprises a further electrically insulating layer, preferably, consisting thereof. The further electrically insulating path may further ensure that the electronic device has enough thickness below the electrically conducting path, particularly below the portion of the electrically conducting path which relates to a skinfacing zone, to provide the required support and / or rigidity for said portion of the electrically conducting path (e.g., the electrode).

[0098] In embodiments, the encapsulant layer comprises at least one from the insulating material group, as described herein with respect to the first aspect of the invention.

[0099] In embodiments, the further electrically insulating path or layer comprises at least one from the insulating material group, as described herein with respect to the first aspect of the invention. In embodiments, the electrically insulating path or layer comprises at least one from the insulating material group and the further electrically insulating path or layer comprises at least one other from the insulating material group. In alternative embodiments, both the electrically insulating path or layer and the further electrically insulating path or layer comprise the same at least one from the insulating material group.

[0100] In embodiments, the shape of the electrode is similar to a shape of the opening, such as aperture or annulus in the electrically insulating layer (i.e., of the inner contour of the aperture or annulus in the electrically insulating layer). The diameter or the sides of the electrode may be greater than or equal to the diameter or sides of the aperture or annulus in the electrically insulating layer (i.e., of the inner contour of the aperture or annulus in the electrically insulating layer). In embodiments, the shape of the electrode is similar to a shape of the portion of the electrically conducting path relating to the skin-facing zone. The diameter or the sides of the electrode may be greater than or equal to, preferably greater than, the diameter or sides of the portion of the electrically conducting path relating to the skin-facing zone. The larger the electrode, the more surface area may be configured to be in contact with the skin. Thus, the electrode can allow for improved electrical conductivity between the electrically conducting path and the skin. In embodiments, the shape of the electrode is similar to a shape of the opening, such as aperture or annulus in the skin adhesive layer (i.e., of the inner contour of the aperture or annulus thereof) relating to the skinfacing zone (i.e., atop the portion of the electrically conducting path relating to the skin-facing zone). The diameter or the sides of the electrode may be greater than or equal to the diameter or sides of the aperture or annulus in the electrically insulating layer (i.e., of the inner contour of the aperture or annulus in the electrically insulating layer). This allows for more effective contact between the electrode and the skin when the electronic device is applied, while ensuring that enough adhesive material is also in contact with the skin to allow for improved attachment to the skin.

[0101] In embodiments, the skin adhesive layer comprises two adhesive sides having an adhesive material, wherein a first adhesive side faces the layer stack, and a second adhesive side is configured to be facing the skin. The adhesive layer, particularly the electrode comprised therein, may comprise a carbon- containing material (e.g., a carbon-loaded adhesive material) or conductive polymer-containing material (e.g., hydrogel).

[0102] In embodiments, the electronic device comprises a release layer stacked atop the skin adhesive layer, preferably further atop the skin-facing zone and / or the electrode. The release layer may be a release liner, e.g., a thin film. The release layer can protect the layer stack, particularly the electrically conducting path, more particularly the portion of the electrically conducting path which relates to the skin-facing zone, from degradation (e.g., due to oxidation, corrosion, temperature fluctuations, humidity, UV radiation, mechanical stress, chemical reactions, etc.). The release layer can protect the skin adhesive layer and / or electrode from dust and / or contamination caused by external factors, such as sticking to other surfaces before the electronic device is applied to its intended surface, i.e., skin. The release layer acts as aprotective cover for the adhesive, allowing it to be easily separated or "released" when needed. Once the release layer is peeled off, the self-adhesive electronic device can be applied to its desired surface.

[0103] In embodiments, the skin adhesive layer, particularly the first adhesive side has a thickness of at most 75 microns, at most 50 microns, at most 45 microns, at most 40 microns, at most 35 microns, at most 30 microns, at most 25 microns. Thus, the first adhesive side may have a thickness in the range of 10-75 microns. In embodiments, the second adhesive side of the skin adhesive layer has a thickness of at most 75 microns, at most 50 microns, at most 45 microns, at most 40 microns, at most 35 microns, at most 30 microns, at most 25 microns. Thus, the second adhesive side may have a thickness in the range of 10-75 microns. The lower thicknesses can allow the electronic device to be more breathable, e.g. through inherent permeability or allowing to apply small opening or vents more easily, while a thicker adhesive layer can provide improved processing thereof (due to the improved handling thereof).

[0104] In embodiments, the electrically conducting path or layer has a thickness of at most 15 microns, at most 14 microns, at most 13 microns, at most 12 microns, at most 11 microns, at most 10 microns, at most 5 microns. In embodiments, at least one of the electrically insulating path or layer and the further electrically insulating path or layer has a thickness of at most 20 microns, at most 18 microns, at most 16 microns, at most 14 microns, at most 12 microns, at most 10 microns, at most 5 microns. In embodiments, at least one, preferably each, of the electrically insulating path or layer and the further electrically insulating path or layer has a thickness of at most 20 microns, at most 18 microns, at most 16 microns, at most 14 microns, at most 12 microns, at most 10 microns, at most 5 microns. The thickness can allow the paths and / or layers to be more breathable, e.g. through inherent permeability or allowing to apply small opening or vents more easily. It will be understood that although each of the paths and / or layers may have the same thickness, it is preferable that each thereof has a respective thickness based on the needs of thereof. For example, for insulation and protection needs the electrically insulating path or layer may have a thickness larger than the electrically conductive path or layer. In embodiments, all paths or layers in the layer stack have similar thicknesses. In preferred embodiments, each of the electrically insulating path or layer and / or the further electrically insulating path or layer have a thickness which is greater than the thickness of the electrically conducting path or layer.

[0105] In embodiments, the release layer has a thickness of at most 250 microns, at most 200 microns, at most 150 microns, at most 100 microns, at most 50 microns.

[0106] In embodiments, the electronic device comprises a stiffening layer stacked atop the encapsulant layer, preferably atop a portion of the encapsulant layer relating to the external interfacing means, i.e., where the external interfacing means can be accessed, such as via an opening, slit or by bending the electronic device). For example, the external interfacing means is a snap button, extending through a slit in the encapsulant layer, wherein the stiffening layer is provided at the bottom side of the encapsulant layer preferably atop a portion surrounding said opening or slit. The stiffening layer may be sandwiched between the top part of the snap button and the encapsulant layer. In another example the external interfacing means is a ZIF connector, accessible by bending part of the electronic device where the ZIF connector is connected to the electrically conducting path, and the stiffening layer is stacked atop the portion of the skin adhesive layer which is stacked atop the ZIF connector. The stiffening layer may provide an additional thickness tothe electronic device, particularly to provide a more rigid portion for allowing a user to connect the external interfacing means more robustly to the connector.

[0107] In embodiments, the stiffening layer has a thickness of at most 200 microns, at most 175 microns, at most 150 microns, at most 125 microns, at most 100 microns, at most 75 microns, at most 50 microns. Thus, the stiffening layer may have a thickness in the range of 20-200 microns. The stiffening layer may comprise an adhesive material, such as a skin adhesive material or another adhesive material.

[0108] In embodiments, the opening in at least one of the skin adhesive layer, the electrically conducting layer, the electrically insulating layer, the further electrically insulating layer, the encapsulant layer, and the release layer, relating to the external interfacing means (i.e., for allowing the extension of the external interfacing means therethrough or for allowing the access to the external interfacing means) may be a slit, such as a cross-shaped slit, e.g. by means of e.g. a die cut, a laser cut, a perforation, etc. In preferred embodiments, the encapsulant layer and the electrically conductive layer each comprises an opening relating to the slit.

[0109] In another second aspect , which is not limiting to the invention, there is provided a system comprising an electronic device according to the other first aspect of the invention, and a connector for connecting the electronic device to the external device, preferably via the external interfacing means. The connector may be connected to the external interfacing means. In embodiments, the connector provides a wired connection between the electronic device to the external device, ice. Alternatively, the connector may provide a wireless connection between the electronic device and the external device. The connector may comprise a complementary connection to the external interfacing means, such as a socket for a snap button or a ZIF connector having compatible pin arrangements that can connect / mate with the external interfacing means being a flat connection (e.g., cable), or pogo pins that can connect / mate with the external interfacing means being a pogo pad.

[0110] In embodiments, the connector comprises a transmitter for transmitting data, such as setting information and / or measurements, to the external device, particularly to a receiver end of the external device. In preferred embodiments, the connector comprises a receiver for receiving signals, such as control signals, preferably from a transmitter end of the external device. The control signals may relate to at least one of: providing a power supply to the electronic device, wireless protocols (e.g., Bluetooth, Wi-Fi, or Zigbee, which enable the sensor to transmit data to the external device directly or indirectly, e.g. via a server or cloud), trigger signals (e.g., electrical inputs that can be used to initiate a specific function in the electronic device), calibration signals (e.g., transmitting reference signals to enable the electronic device to accurately measure physical parameters), control parameters (e.g., adjustable parameters that allow the user to modify the behaviour of the electronic device) and software commands (e.g., instructions transmitted to the electronic device to modify settings and / or behaviour of the electronic device).

[0111] In embodiments, the system comprises the external device. The external device may comprise a display and / or a graphical user interface (GUI). The GUI may allow the user to visualize the received data from the electronic device, e.g. on the display of the external device. The GUI may allow the user to select and / or generate control signals to transmit to the electronic device. The external device may be a sever or a cloud server, a portable electronic device (e.g., laptop, smart phone, etc.), etc.

[0112] In embodiments, the system comprises a printed circuit board (PCB). The PCB may serve as the connector for providing a connection between the electronic device and the external device. The PCB may be a flexible PCB. The flexible PCB may still allow the electronic device to be flexible and comfortable to the user when applied to their skin compared to electronic devices where rigid connectors are used.

[0113] In another third aspect, which is not limiting to the invention, there is provided a process for fabricating at least one electronic device according to the other first aspect of the present invention, the process comprising: providing a transfer layer, forming an encapsulant layer atop the transfer layer, forming a layer stack atop the encapsulant layer, forming a skin adhesive layer atop the layer stack and the encapsulant layer and preferably the transfer layer, and separating the transfer layer from the formed layers (i.e., the encapsulant layer and preferably the skin adhesive layer), wherein the step of forming a layer stack comprises: forming an electrically conducting path atop the transfer layer, and preferably forming an electrically insulating path atop the electrically conducting path and more preferably the encapsulant layer, wherein a portion of the electrically conducting path relates to a skin-facing zone configured to be facing the skin, wherein the skin adhesive layer comprises a first adhesive side and a second adhesive side each having an adhesive material, wherein the first adhesive side is configured to be facing the skin. wherein a first portion of the second adhesive side faces the layer stack, and a second portion of the second adhesive side faces the encapsulant layer.

[0114] Advantageously, the separating of the transfer layer (e.g., peeling off) only takes place at the very end of the formation of the layers (e.g., the build-up of layers). This ensures that a substrate is not needed to provide support for the formed layers, thus allowing to reduce the number of layers.

[0115] In embodiments, the skin adhesive layer comprises a further adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side faces the encapsulant. Preferably, the skin adhesive layer comprises an aperture or an annulus. The aperture (e.g., a hole in the skin adhesive layer) may provide the skin-facing zone for the electrically conducting path. The annulus may relate to the space within a ring formed by the skin adhesive layer and may provide the skin-facing zone for the electrically conducting path.

[0116] In embodiments, the process for fabricating at least one electronic device relates to a method for manufacturing the at least one electronic device.

[0117] In embodiments, a first step is providing a transfer layer. A second step is forming the encapsulant layer atop the transfer layer. A third step is forming the layer stack atop the encapsulant layer. The thirdstep comprises forming the electrically conducting layer atop the encapsulant layer and preferably forming the electrically insulating layer atop the electrically conducting layer and more preferably further atop the encapsulant layer. A fourth step is forming the skin adhesive layer atop the layer stack and the encapsulant layer and optionally the transfer layer. The first step may be provided by applying a pre-existing transfer layer (e.g., a transfer film that has already been used). At least one, preferably all, of the second, and third steps may be performed by printing a respective material (e.g., ink). The first step may be performed by laminating the encapsulant layer. The fourth step may be performed by applying, e.g., laminating, a preexisting skin adhesive layer.

[0118] In embodiments, the skin adhesive layer may be partially formed atop a portion of the transfer layer, particularly atop a portion of the transfer layer where the encapsulant layer is not formed.

[0119] In preferred embodiments, a portion of the electrically conducting path relates to the skin-facing zone configured to be facing the skin.

[0120] In advantageous embodiments, the transfer layer is separated from the encapsulant layer, and preferably from the skin adhesive layer. The transfer layer may thus be reused for fabricating or manufacturing a plurality of electronic devices.

[0121] In embodiments, the process comprises forming a release layer atop the adhesive layer. The release layer may further be formed atop the electrode (e.g., in the electrically conducting path) and / or the opening in the skin adhesive layer relating to skin-facing zone. The release layer may be formed before or after which the transfer layer has been separated from the encapsulant layer. The forming of the release layer may be performed by applying a pre-existing release layer. The release layer may be comprised in the skin adhesive layer, particularly atop the first adhesive side of the skin adhesive layer.

[0122] In embodiments, the invention may relate to providing the external interfacing means in array before singularization into individual electronic devices. The singularization may relate, e.g., to die cutting, lasering, perforating, snapping, etc. Thus, the process comprises a step of dividing (i.e., singularizing) the formed layers into at least two electronic devices after providing the external interfacing means. The formed layers may include the formed encapsulant layer, the layer stack and the skin adhesive layer, preferably in addition to the release layer. In alternative embodiments, the invention may relate to providing the external interfacing means in array after singularization into individual electronic devices. Thus, the process comprises a step of dividing the formed layers into at least two electronic devices before providing the external interfacing means.

[0123] In embodiments, the opening in at least one of the skin adhesive layer, the electrically conducting layer, the electrically insulating layer, the further electrically insulating layer, the encapsulant layer, and the release layer, (i.e., for allowing the extension of the external interfacing means therethrough or for allowing the access to the external interfacing means) relating to the external interfacing means may be provided during the step of singularization. Preferably, the opening in at least the encapsulant layer and the electrically conducting layer relating to the external interfacing means may be provided during the step of singularization.

[0124] In another fourth aspect, which is not limiting to the invention, there is provided a kit comprising at least one electronic device according to the other first aspect of the present invention, preferably a system according to the other second aspect of the present invention; and a set of instructions and / or illustrationsdirecting a user to adhere the electronic device onto the skin. Such instructions may be printed on the release layer (e.g. on the surface facing away from the layer stack and / or skin adhesive layer), on a package in which the electronic device or system is provided, on the skin adhesive layer (e.g., the surface facing away from the layer stack or configured to be facing away from the skin), or on a separate paper or booklet in the kit.

[0125] In another fifth aspect, which is not limiting to the invention, there is provided a device set comprising a plurality of electronic devices according to the other first aspect of the present invention, preferably a system set comprising a plurality of systems according to the other second aspect of the present invention.

[0126] In embodiments, the device set comprises a plurality of attached electronic devices (i.e., not singularized).

[0127] In embodiments, the system set comprises a device set and a plurality of respective connectors for connecting the respective electronic device to the external device, preferably via the respective external interfacing means.

[0128] In embodiments, the process for fabricating at least one electronic device, preferably a plurality of electronic devices or at least one device set, more preferably a plurality of device sets according to the present invention, comprises: providing a (common) transfer layer, forming respective encapsulant layers atop the transfer layer, forming respective layer stacks atop the respective encapsulant layers, forming respective skin adhesive layers atop the respective layer stacks and the respective encapsulant layers, and separating the respective transfer layers from the respective encapsulant layers, the respective layer stacks and the respective skin adhesive layers, wherein the step of forming respective layer stacks comprises: forming respective electrically conducting paths atop the respective encapsulant layers, and preferably forming respective electrically insulating paths atop the respective electrically conducting layers, wherein respective portions of the respective electrically conducting paths relate to respective skinfacing zones configured to be facing the skin, wherein the respective skin adhesive layers comprise respective first adhesive sides and respective second adhesive sides each having an adhesive material, wherein the respective first adhesive sides are configured to be facing the skin. wherein respective first portions of the respective second adhesive sides face the respective layer stacks, and respective second portions of the respective second adhesive sides face the respective encapsulant layers.

[0129] Example embodiments of the invention will be described with reference to Fig. 1-3, 4A, 4B, 5A, 5B, 6A-6G.Example 1: first example electronic device according to the invention

[0130] The first example is described with reference to Fig. 1. In this example, there is provided a device set (10) comprising a plurality of, particularly four, electronic devices suitable for skin contact, each of electronic devices comprising: an encapsulant layer (11 ); a layer stack stacked atop the encapsulant (11 ), wherein the layer stack comprises an electrically conducting path and an electrically insulating path stacked atop the electrically conducting path; and a skin adhesive layer (15) stacked atop the layer stack, wherein the skin adhesive layer (15) comprises a first adhesive side and a second adhesive side each having an adhesive material, wherein the first adhesive side is configured to be facing the skin, wherein a first portion of the second adhesive side faces the layer stack, and a second portion of the second adhesive side faces the encapsulant layer (11), wherein a portion (13a) of the electrically conducting path relates to a skin-facing zone configured to be facing the skin.

[0131] In each of the electronic devices, the electrically conducting path comprises an electrically conducting layer (13), and the electrically insulating path comprises an electrically insulating layer (12).

[0132] In the example device set, in each electronic device, the electrically conductive path further comprises an electrode (18). The skin adhesive layer (15) comprises a first opening (15a), such as a first aperture or a first annulus. The size of the electrode (18), such as the diameter, is greater than or equal to the diameter of the first opening (15a) in the skin adhesive layer (15). The electrode (18) relates to the skinfacing zone configured to be facing the skin and preferably in contact therewith. As can be seen, given the larger diameter of the electrode (18) compared to the portion (13a) of the electrically conducting path, the electronic device can more effectively conduct electrical signals or current between the skin and the electrically conducting path and further with the external interfacing means (19).

[0133] As may be seen in the Fig. 1 , the example electronic device set (10) further comprises in each of the electronic devices external interfacing means (19), particularly a snap button, configured for connecting the respective electronic device to an external device (not shown). The external interfacing means (19) extends in the direction from the skin adhesive layer (15) to the encapsulant layer (11), i.e., away from the skin. The skin adhesive layer (15) in each electronic device comprises a second opening (15b), such as a second aperture or a second annulus. The second opening (15b) is shown to have a larger size, i.e., diameter, compared to that of the external interfacing means (19), to allow the external interfacing means (19) to extend therethrough. The electrically insulating layer (12) comprises a second opening (12b), such as an aperture or an annulus, and the electrically conducting layer (13), comprises a second opening, particularly a cross-shaped slit (13b). The size of the second opening (12b) in the electrically insulating layer may be smaller than that of the largest part of the external interfacing means (19), such as the base of, e.g. snap button, and larger than the smallest part of the external interfacing means (19), such as the head of, e.g. snap button. It may be seen that the second openings (12b, 13b, 15b) relate to the externalinterfacing means (19) (i.e., for allowing the extension of the external interfacing means therethrough or for allowing the access to the external interfacing means).

[0134] In this example, the paths and / or layers are provided over an encapsulant layer (1 1) which serves as a substrate. Although not shown here, the fabrication of the example device set makes use of a transfer layer, making it possible to avoid PU, TPU, or other substrate materials as a substrate. This makes it possible to obtain much thinner devices, which can therefore be more conformable when one (device) is applied to the skin, which is advantageous. It also makes it possible to avoid additional lamination, such as textile, non-woven etc, which reduces the cost and further makes it possible to keep the device thin.

[0135] It will be understood that each path and / or layer is formed for all the plurality of electronic devices in the device set (10) and not for each electronic device separately. This allows for a more efficient and faster way of fabricating more electronic devices.Example 2: second example electronic device according to the invention

[0136] This example is described with reference to Fig. 2. In this example, there is provided a device set (20) comprising a plurality of, particularly four, electronic devices suitable for skin contact, each of electronic devices comprising: a layer stack comprising an electrically insulating path and an electrically conducting path at least partially stacked atop the electrically insulating path; a skin adhesive layer (25) stacked atop the layer stack; and a release layer (26) atop of which the layer stack and the skin adhesive layer (25) are stacked, wherein the skin adhesive layer (25) comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin, wherein a portion (23a) of the electrically conducting path relates to a skin-facing zone configured to be facing the skin.

[0137] In each of the electronic devices, the electrically conducting path (23) consists of an electrically conducting layer (23), and the electrically insulating path (22) consists of an electrically insulating layer (22).

[0138] In the example device set (20), in each electronic device, the portion (23a) of electrically conductive path may serve as an electrode, since the diameter thereof is larger compared to the portion (13a) of electrically conductive path shown in Fig. 1 . As can be seen, given the larger diameter of the portion (23a) of electrically conductive path, the electronic device can more effectively conduct electrical signals or current between the skin and the electrically conducting path and further with the external interfacing means (19), without the need for an electrode, thereby reducing the size of the electronic device. However, to further improve conductivity, an electrode may be provided atop of which the portion (13a) of the electrically conducting path relating to the skin-facing zone is located or the skin adhesive comprise the electrode on the adhesive side atop of the portion (13a) of the electrically conducting path, preferably having a larger diameter than that of the portion (13a) of the electrically conducting path.

[0139] As may be seen in the Fig. 2, the example electronic device set (20) further comprises in each of the electronic devices external interfacing means (29), particularly a snap button, configured for connecting the respective electronic device to an external device (not shown). The external interfacing means (29) extends in the direction from the release layer (21) to the skin adhesive layer (25), i.e., away from the skin. The skin adhesive layer (25) in each electronic device comprises an opening (25b), such as an aperture or an annulus. The opening (25b) is shown to have a larger size, i.e., diameter, compared to that of the external interfacing means (29), however, it can also be imagined that the size of the opening (25b) may be smaller than that of the largest part of the external interfacing means (29), such as the base of, e.g. snap button, and larger or smaller than the smallest part of the external interfacing means (29), such as the head of, e.g. snap button. The layer stack, particularly each of the electrically insulating layer (22) and the electrically conducting layer (23), comprises an opening, such as an aperture or an annulus. The size of the opening in the layer stack or in each layer therein may be smaller than that of the largest part of the external interfacing means (29), such as the base of, e.g. snap button, and larger or smaller than the smallest part of the external interfacing means (29), such as the head of, e.g. snap button. As can be seen in Fig. 2, the size of the opening in the electrically conductive layer (23) is smaller than that of the electrically insulating layer (22).

[0140] In Example 1 , the paths and / or layers are provided over an encapsulant layer (11 ) which serves as a substrate. Although not shown here, the fabrication of the example device set makes use of a transfer layer, making it possible to avoid PU, TPU, or other substrate materials as a substrate. This makes it possible to obtain much thinner devices, which can therefore be more conformable when one (device) is applied to the skin, which is advantageous. It also makes it possible to avoid additional lamination, such as textile, non-woven etc, which reduces the cost and further makes it possible to keep the device thin. It can be seen that the electronic device or device set (20) in Fig. 2 is even thinner than the electronic device or device set (10) in Fig. 1 .

[0141] It will be understood that each path and / or layer is formed for all the plurality of electronic devices in the device set (20) and not for each electronic device separately. This allows for a more efficient and faster way of fabricating more electronic devices.Example 3: third example electronic device and system according to the invention

[0142] This example is described with reference is made to Fig. 3. In this example, there is provided an electronic device. The electronic device is suitable for skin contact and comprises: a layer stack comprising an electrically insulating path and an electrically conducting path at least partially stacked atop the electrically insulating path; a skin adhesive layer (35) stacked atop the layer stack; and a release layer (36) atop of which the layer stack and the skin adhesive layer (35) are stacked, wherein the skin adhesive layer (35) comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin, wherein two portions (33a) of the electrically conducting path relates to respectively two skin-facing zones configured to be facing the skin.

[0143] The electrically conducting path comprises a plurality of, particularly two, electrically conducting layers (33) and respectively a plurality of, particularly two, electrodes (37), and the electrically insulating path comprises a plurality of, particularly two, electrically insulating layers (32) and respectively a plurality of, particularly two, openings (32a), such as apertures or annuli. The openings (32a) may relate to the skinfacing zones, wherein the respective portions (33a) of the electrically conducting path are at least partially stacked atop the openings (32a) in the electrically insulating path. The electrodes (37) are provided for allowing the electrically conducting layers (33) to be in contact with the skin via the electrodes (37) respectively. Thus, the electrodes (37) respectively connect the electrically conducting layers (33), and further the external interfacing means (39a, 39b), to the skin through the respective openings (32a) in the electrically insulating path.

[0144] As may be seen in the Fig. 3, the example electronic device comprises respective external interfacing means (39a, 39b), particularly snap buttons: top parts (39a) of the snap buttons and bottom parts (39b) of the snap buttons, configured for connecting the electronic device to an external device (not shown) via the connector (38). The external interfacing means (39) extend in the direction from the electrically conducting path, particularly the respective electrically conducting layer to and preferably through the skin adhesive layer (35), i.e., away from the skin. The skin adhesive layer (35) in the electronic device comprises openings (35b), particularly cross-shaped slits. The electrically insulating layers (32) do not need to include additional openings for the external interfacing means (as in Fig. 2).

[0145] As shown in Fig. 3, the electrically insulating layer (32) and the electrically conducting layer (33) comprise complementary shapes. The shapes are complementary in that the electrically conducting layer (33) can be surrounded by the electrically insulating layer (32), such as they have the same shape where the electrically insulating layer (32) has a wider shape than the electrically conducting layer (33).

[0146] As further shown in Fig. 3, there is provided a connector (38) comprising complementary connections, i.e., sockets, for connecting to the respective external interfacing means (39a), i.e., the top part (39a) of the snap buttons. Thus, we can see a system comprising the electronic device and the connector (38) for connecting the electronic device to the external device, via the external interfacing means (39a, 39b). Here, the connector (38) may provide a wireless connection between the electronic device to the external device.Example 4: fourth example electronic device according to the invention

[0147] This example is described with reference to Fig. 4A, 4B, 5A and 5B. In Fig. 4A and 4B, there is provided an electronic device (40) suitable for skin contact, the electronic device (40) comprises: a layer stack comprising an electrically insulating path, an electrically conducting path at least partially stacked atop the electrically insulating path, and a further electrically insulating path at least partially stacked atop the electrically conducting path; a skin adhesive layer (45) stacked atop the layer stack; and a release layer (46) atop of which the layer stack and the skin adhesive layer (45) are stacked, wherein the skin adhesive layer (45) comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin,wherein a portion (43a) of the electrically conducting path relates to a skin-facing zone configured to be facing the skin.

[0148] The skin adhesive layer is a conformal layer which covers the steps, corners and curves of the layer stack in a substantially uniform manner.

[0149] The electrically conducting path comprises an electrically conducting layer (43) and a portion (43a) of the electrically conducting path relates to a skin-facing zone configured to be facing the skin. The electrically insulating path comprises or even consists of an electrically insulating layer (42). The further electrically insulating path consists of a further electrically insulating layer (44).

[0150] The electrically conducting path, particularly the portion (43a) relating to the skin-facing zone extends longitudinally beyond the electrically insulating layer (42), to be configured to contact the skin, as can be seen in Fig. 4A. As can be seen in Fig. 4B, the electrically insulating layer (42), particularly the portion at an opposite end to the skin-facing zone is wider than the electrically conducting layer (43) and the portion of the electrically conducting path (43a). Said opposite end is the portion relating to the externally interfacing means, i.e., wherein the external interfacing means extend along the transverse axis in the direction away from the portion of the electrically insulating layer (42) relating to the externally interfacing means. An example of said portion of the electrically insulating layer and the externally interfacing means can be visualized in Fig. 2, where said portion of the electrically insulating layer (22), i.e., where the opening 22b is located, is larger in width (along the third orthogonal axis to the longitudinal and transverse axes) than that of the portion (23a) of the electrically conducting path.

[0151] The electronic device (50) described with reference to Fig. 5A and 5B corresponds in many aspects and / or features to the electronic device (40) of Fig. 4A and 4B, therefore, only the difference will be described in detail for the sake of brevity.

[0152] The layers (53, 53, 54, 55, 56) comprised in the electronic device (50) correspond to the layers (42, 43, 44, 45, 46) comprised in the electronic device (40). The electrically conducting path in the electronic device (50) consists of an electrically conducting layer (53), and an electrode (57) is laminated at the bottom side of the electrically conducting layer (53), particularly on the skin-facing portion, i.e., the side configured to be facing the skin, which is provided for allowing the electrically conducting layer (53) to be in contact with the skin via the electrode (57). Thus, the electrode (57) is configured to connect the electrically conducting layer (53) to the skin through the respective opening in the electrically insulating path.

[0153] As can be seen in Fig. 5A, the electrically conducting layer (53) is at least partially stacked atop the electrically insulating layer (52). The electrode (57) is laminated at the bottom side of the electrically insulating layer (52), particularly only a portion thereof (i.e., at one end), covering the steps, corners and / or curves of the one end of the electrically insulating layer (52) (i.e., relating to the skin-facing zone) As can be seen in Fig. 5B, the electrically insulating layer (52), particularly the portion at an opposite end to the skin-facing zone is wider than the electrically conducting layer (53) and the portion of the electrically conducting path (53a), as well as the electrode (57). . However, it would be advantageous to have an even wider electrode (57), i.e., a larger diameter than that of the opposite end of the electrically insulating layer (52) and / or electrically conducting layer (53).Example 5: fifth example electronic device according to the invention

[0154] This example is described with reference to Fig. 6A-6G, where there is provided in each figure a respective electrically conducting path comprising an electrically conducting layer (63), an opening (63b), particularly a slit, and a respective portion (67a, 67b, 67c, 67d, 67e, 67f, 67g) relating to the skin-facing zone.

[0155] The respective portions of the electrically conducting paths relating to the skin-facing zone comprises a conductive material and a plurality of openings. The shape of the portion of the electrically conducting path relating to the skin-facing zone is circular.

[0156] In Fig. 6A, the portion (67a) of the electrically conducting path comprises a grid structure or lattice of electrically conductive material and further comprising openings relating to the interstitial / void / pore space. Here, the ratio of the openings to the conductive material is at least 1.5:1.

[0157] In Fig. 6B, 6C and 6D, each of the portions (67b, 67c, 67d) of the electrically conducting path comprises a plurality of arcs and radii, wherein the radii extend from the center of the respective portion to the end points of the respective arc that forms the boundary between two subsequent radii. Each arc and its respective two subsequent radii define a sector (a portion of the circle) which relates to a respective opening. In Fig. 6B, the portion (67b) comprises 6 openings (i.e., the 6 sections), and the conductive material (i.e., the 6 arcs and the 6 radii). The ratio of the openings to the conductive material is at least 3:1 . In Fig. 6C, the portion (67c) comprises 4 openings (i.e., the 4 sections), and the conductive material (i.e., the 4 arcs and the 4 radii). The ratio of the openings to the conductive material is at least 4:1. In Fig. 6D, the portion (67d) comprises 4 openings (i.e., the 4 sections), and the conductive material (i.e., the 4 arcs and the 4 radii). Here, the conductive material is thicker than that of portion (67c) of Fig. 6C. The ratio of the openings to the conductive material is at least 2:1.

[0158] In Fig. 6E, 6F, and 6G, each of the portions (67e, 67f, 67g) of the electrically conducting path comprises a conductive material in the shape of nested circles and a diagonal connecting each of these nested circles to each other. The electrically conducting path further comprises openings relating to the annular regions between the nested circles. In Fig. 6E, the portion (67e) comprises the conductive material (i.e., 4 nested circles), and the 8 openings (i.e., the 8 annular regions between the nested circles and the diagonal). The ratio of the openings to the conductive material is at least 1.5:1 . In Fig. 6F, the portion (67f) comprises the conductive material (i.e., 2 nested circles), and the 4 openings (i.e., the 4 annular regions between the nested circles and the diagonal). The ratio of the openings to the conductive material is at least 4:1. In Fig. 6D, the portion (67e) comprises the conductive material (i.e., 2 nested circles), and the 2 openings (i.e., the 2 annular regions between the nested circles and the diagonal). Here, the conductive material is thicker than that of portion (67f) of Fig. 6F, and the most nested circle is filled with the conductive material. The ratio of the openings to the conductive material is at least 2:1 .

[0159] (End of example 5)

[0160] The above-described inventive concepts are illustrated by several illustrative embodiments. It is conceivable that individual inventive concepts may be applied without, in so doing, also applying other details of the described example. It is not necessary to elaborate on examples of all conceivable combinations of the above-described inventive concepts, as a person skilled in the art will understand numerous inventive concepts can be (re)combined in order to arrive at a specific application.

[0161] Although the present invention has been described above with reference to certain embodiments thereof, it will be evident that various modifications and changes may be made to these embodiments without departing from the broader scope of the present invention, as defined by the appended claims.

Claims

Claims1 . A process for fabricating at least one electronic device suitable for skin contact, the electronic device comprising: a layer stack comprising an electrically insulating path and an electrically conducting path stacked atop the electrically insulating path; and a skin adhesive layer (25) stacked atop the layer stack; the process comprising: providing a transfer layer, forming the layer stack atop the transfer layer, forming the skin adhesive layer atop the layer stack and the transfer layer, and separating the transfer layer from the layer stack and the skin adhesive layer, wherein the step of forming the layer stack comprises: forming an electrically insulating path atop the transfer layer, and forming an electrically conducting path atop the electrically insulating path, wherein a portion of the electrically conducting path relates to a skin-facing zone (23a) configured to be facing the skin, wherein the skin adhesive layer (25) comprises an adhesive side having a skin adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin.

2. The process according to claim 1 comprising: providing external interfacing means; and dividing the formed layers into at least two electronic devices before or after providing the external interfacing means.

3. The process according to claim 1 or 2, further comprising: providing a masking film with a geometry comprising openings corresponding to ink regions; applying the masking film over the formed layer stack; wherein the geometry of the masking film is such that at least 80% of the skin adhesive layer, preferably essentially the entire skin adhesive layer, touches either the layer stack or the masking film and not the transfer layer.

4. The process according to claim 3, wherein at least part of, preferably all of, the masking film relates to a release liner.

5. The process according to claims 1-4, wherein the skin adhesive layer is provided with a release liner, the process further comprising: partially removing, from the release liner of the skin adhesive layer (25), segments corresponding to layer stack zones; wherein the steps of forming the skin adhesive layer atop the layer stack and the transferlayer and separating the transfer layer therefrom relates to selectively transferring the layer stack onto the skin adhesive layer.

6. The process according to claim 5, wherein the partial removal relates to the release liner being pre-cut.

7. The process according to claim 6, wherein the being pre-cut relates to kiss-cutting using a laser and / or die-cutting.

8. An electronic device suitable for skin contact, preferably the device manufactured with the process according to claims 1-7, the electronic device comprising: a layer stack comprising an electrically insulating path and an electrically conducting path stacked atop the electrically insulating path; and a skin adhesive layer (25) stacked atop the layer stack, wherein a portion (23a) of the electrically conducting path relates to a skin-facing zone configured to be facing the skin, wherein the skin adhesive layer (25) comprises an adhesive side having an adhesive material, wherein a first portion of the adhesive side faces the layer stack, and a second portion of the adhesive side is configured to be facing the skin.

9. The electronic device according to claim 8, wherein the layer stack comprises a further electrically insulating path stacked atop the electrically conducting path.

10. The electronic device according to claim 8 or claim 9, wherein the electrically conducting path consists of an electrically conducting layer (23) and / or at least one of the electrically insulating path and the further electrically insulating path consists of an electrically insulating layer (22).11 . The electronic device according to any of claims 8-10, wherein the electrically conducting path comprises an electrically conducting layer (33) and an electrode (37).

12. The electronic device according to claim 11 , wherein the electrode (37) is at least partially comprised in the portion (23a) of the electrically conducting path relating to the skin-facing zone.

13. The electronic device according to any of claims 8-12, wherein the skin adhesive layer (25) comprises an electrode, preferably the electrode is stacked atop the portion of the electrically conducting path relating to the skin-facing zone (23a).

14. The electronic device according to any of claims 8-13, wherein the electrically insulating path and / or the further electrically insulating path comprises vents.

15. The electronic device according to any of claims 8-14, further comprising a release layer (26) atop of which the layer stack and the skin adhesive layer (25) are stacked.

16. The electronic device according to any of claims 8-15, further comprising external interfacing means (29) configured for connecting the electronic device to an external device, preferably wherein the external interfacing means (29) is electrically connected to the electrically conducting path.

17. The electronic device according to claim 16, further comprising a stiffening layer stacked atop the skin adhesive layer (25), preferably atop a portion of the skin adhesive layer (25) relating to the external interfacing means (29).

18. The electronic device according to any of claims 8-17, wherein the portion of the electrically conducting path comprises a conductive material and a plurality of openings, preferably wherein the ratio of the openings to the conductive material is at least 1.5:1 , more preferably at least 3:1 .

19. A system comprising: an electronic device according to any of claims 8-18 and / or an electronic device manufactured with the process according to any of claims 1-7; and a connector (38) for connecting the electronic device to the external device, preferably via the external interfacing means (39a, 39b).

20. A kit comprising: an electronic device according to any of claims 1-18 and / or an electronic device manufactured with the process according to any of claims 1-7, preferably the system according to claim 19; and a set of instructions and / or illustrations directing a user to adhere the electronic device onto the skin.21 . An electronic device suitable for skin contact, the electronic device comprising: an encapsulant layer (11 ); a layer stack stacked atop the encapsulant (1 1 ), wherein the layer stack comprises an electrically conducting path; and a skin adhesive layer (15) stacked atop the layer stack and the encapsulant layer, wherein a portion (13a) of the electrically conducting path relates to a skin-facing zone configured to be facing the skin, wherein the skin adhesive layer (15) comprises a first adhesive side and a second adhesive side each having an adhesive material, wherein the first adhesive side is configured to be facing the skin. wherein a first portion of the second adhesive side faces the layer stack, and a second portion of the second adhesive side faces the encapsulant layer (11 ).

22. The electronic device according to claim 21 , wherein the layer stack comprises an electrically insulating path stacked atop the electrically conducting path.

23. The electronic device according to claim 21 or claim 22, wherein the encapsulant layer and / or the electrically insulating path comprises vents.

24. The electronic device according to any of claims 21-23, wherein the electrically conducting path consists of an electrically conducting layer (13) and / or the electrically insulating path consists of an electrically insulating layer (12).

25. The electronic device according to any of claims 21-23, wherein the electrically conducting path comprises an electrically conducting layer (13) and an electrode (18).

26. The electronic device according to claim 25, wherein the electrode (18) is at least partially comprised in the portion (13a) of the electrically conducting path relating to the skin-facing zone.

27. The electronic device according to claim 26, wherein the skin adhesive layer (15) comprises an opening (15a), preferably in a portion of the skin adhesive side relating to the skin-facing zone.

28. The electronic device according to claim 27, wherein the opening (15a) has a diameter equal to the diameter of the electrode (18).

29. The electronic device according to any of claims 21-28, further comprising a release layer stacked atop the skin adhesive layer (15).

30. The electronic device according to any of claims 21-29, further comprising external interfacing means (19) configured for connecting the electronic device to an external device. preferably wherein the external interfacing means (19) is electrically connected to the electrically conducting path.

31. The electronic device according to claim 30, further comprising a stiffening layer stacked atop the encapsulant (11 ), preferably atop a portion of the encapsulant relating to the external interfacing means (19).

32. A system comprising: an electronic device according to any of claims 21-31 ; and a connector for connecting the electronic device to the external device, preferably via the external interfacing means.

33. A process for fabricating at least one electronic device according to any of claims 21-31 , the process comprising: providing a transfer layer, forming an encapsulant layer atop the transfer layer, forming a layer stack atop the encapsulant layer, forming a skin adhesive layer atop the layer stack and the encapsulant layer, and separating the transfer layer from the encapsulant layer, the layer stack and the skin adhesive layer, wherein the step of forming a layer stack comprises: forming an electrically conducting path atop the encapsulant layer, and preferably forming an electrically insulating path atop the electrically conducting layer, wherein a portion of the electrically conducting path relates to a skin-facing zone configured to be facing the skin, wherein the skin adhesive layer comprises a first adhesive side and a second adhesive side each having an adhesive material, wherein the first adhesive side is configured to be facing the skin. wherein a first portion of the second adhesive side faces the layer stack, and a second portion of the second adhesive side faces the encapsulant layer.

34. The process according to claim 33, comprising: providing external interfacing means; anddividing the formed layers into at least two electronic devices before or after providing the external interfacing means.

35. A kit comprising: an electronic device according to any of claims 21-31 , preferably a system according to claim 32; and a set of instructions and / or illustrations directing a user to adhere the electronic device onto the skin.

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