Conductive layer structure having a multi-layer conductive configuration

Abstract

An electrically conductive layer structure (10) for application to a surface (12) of a subject, particularly for use in a medical product, comprises a first electrically conductive layer (14) having at least one electrically conductive path (16), at least one other electrically conductive layer (14) having at least one electrically conductive path (16), and at least one intermediate layer (24) extending at least partially between the first and other electrically conductive layers (14), at least portions of the first and other electrically conductive layers (14) being arranged one on top of the other within the layer structure (10), and the layer structure (10) being elastically extensible.

Description

[Technical field]

[0001] The present invention relates to an electrically conductive layer structure for application to the surface of a subject, in particular for use in medical products. The invention also relates to a method for producing said layer structure. The layer structure is adapted for acquiring biometric parameters of a subject, in particular for performing electrocardiography (ECG), electroencephalography (EEG), electromyography (EMG), electroplethysmography (EOG), microcardioversion and / or defibrillation on the subject. [Background technology]

[0002] In both medical and non-medical fields, a wide variety of layer structures comprising electrically conductive elements are employed to interact with the surface of a subject, for example the body of a patient.

[0003] For example, layer structures in the form of electrode patches are used for ECG monitoring (ECG: electrocardiography), i.e. to obtain biometric parameters of a subject. Typically, electrode patches comprise electrically conductive (short for "conductive / conductive") paths connecting the electrodes to a device for measuring signals generated at and detected by the electrodes.

[0004] Prior art electrode patches are known from U.S. Patent No. 6,399,633, the disclosure of which is incorporated herein by reference in its entirety. This teaching describes several use cases for the prior art electrode patches and the electrode patches disclosed herein, which use cases are equally applicable to the layer structures disclosed herein.

[0005] Furthermore, the layer structure may be used, for example, for EMS clothing (EMS: Electrical Muscle Stimulation).

[0006] The layer structure, and in particular the electrode patch, must meet various requirements, such as size limitations leading to a high level of miniaturization and / or compactness.

[0007] Compactness is particularly related to the footprint, i.e. the base area, of the layer structure, which determines the area that the layer structure occupies on the surface of the subject. By limiting the footprint or area, it may be possible, for example, to reduce the complexity of the layer structure on the subject and / or to speed up the installation. This may also mean that the surface of the subject is occupied less, which leaves room for the installation of further layer structures or other medical systems. Size limitations may also reduce manufacturing and material costs.

[0008] Furthermore, it has been determined that increasing compactness can reduce the efficiency and reliability of the layer structure.

[0009] It has also generally been found that prior art structures can be difficult to apply due, for example, to difficulties in handling and positioning on the patient. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] European Patent Application Publication No. 3626158 Summary of the Invention [Problem to be solved by the invention]

[0011] It is an object of the present invention to provide a layer structure for application to the surface of an object, which overcomes at least some of the above-mentioned drawbacks, such as difficult handling, low efficiency and reliability, or low compactness.

[0012] In particular, it is an object of the present invention to provide a layer structure that has a compact design in order to realize a sufficiently reliable and / or efficient signal measurement.

[0013] It is a further object of the present invention to provide a layer structure that can be easily and quickly attached to a subject.

[0014] These objects are achieved by the subject matter of the independent claims. Optional embodiments and optional features are defined in the dependent claims and the following description. [Means for solving the problem]

[0015] An aspect of the present invention relates to a layer structure for application to a surface of a subject, in particular for use in medical products, the layer structure comprising: a first conductive layer having at least one conductive path; at least one other conductive layer having at least one conductive path; at least one intermediate layer extending at least partially between the first and other conductive layers; Equipped with At least parts of the first and other conductive layers are arranged on top of each other, or in other words are stacked on top of each other with an intermediate layer between them. In particular, the conductive layers may be arranged to overlap and / or cross (but preferably not touch) each other in the layer structure (e.g. when viewed along an axis extending perpendicular to the surface of the object and / or the plane of the layers). In other words, at least a portion of the first conductive layer and a portion of the other conductive layer may be arranged congruently in the layer structure.

[0016] At least two layers and preferably all layers, or at least the conductive layer and / or the intermediate layer, may be immovable relative to one another. Preferably, these layers are directly or indirectly fixed to one another, for example, rather than simply being on top of one another and being movable relative to one another. Typically, the layer structure may be provided as a single integrated unit, with the components fixed within the layer structure and / or relative to one another. However, this state will already be given before attachment to the patient, for example when the layer structure is removed from the packaging.

[0017] As a generally preferred feature, the layer structure is elastically extensible. Moreover, the invention also relates to non-elastically extensible layer structures having the above mentioned features, which may be combined with or constructed according to any of the further aspects disclosed herein.

[0018] The elasticity of the layer structure or individual layers reduces negative motion artifacts and improves positioning in the subject. The layer structure may be longitudinally extensible in the range of 1% to 1000%, preferably 100% to 900%, more preferably 200% to 800%, even more preferably 300% to 500%, even more preferably 350% to 450%. Each of the layers of the layer structure may be longitudinally extensible in the range of 1% to 1000%, preferably 100% to 900%, more preferably 200% to 800%, even more preferably 300% to 500%, even more preferably 350% to 450%. Each of the conductive layers may have a longitudinal extensibility of 1.0 to 100.0 N / mm 2 , preferably 2.0 to 50.0 N / mm 2 , more preferably 3.0 to 25 N / mm 2 , and more preferably 5.0 to 15.0 N / mm 2 The elastic modulus (E-modulus) may be

[0019] A medical product in which the layer structure may be used may be a medical patch, particularly an electrode patch.

[0020] The inventors have generally recognized a conflict of interest between achieving a compact design and satisfying efficiency and / or reliability.

[0021] For example, to make a conductive layer structure more compact, it may be necessary to reduce the cross section of the conductive paths within the layer structure, which allows multiple conductive paths to be densely packed.

[0022] However, as a result, the applicable voltage and current are reduced and the ohmic resistance of the conductive path increases, which reduces efficiency.

[0023] Also, dense packaging can make the conductive paths susceptible to noise, for example due to crosstalk and / or interference between adjacent paths, which also limits the efficiency and, more precisely, the measurement accuracy.

[0024] Furthermore, when a large number of conductive paths are integrated in a dense layer structure, the previously remaining available space for, for example, protective layers is significantly reduced.

[0025] Furthermore, as part of achieving the desired reliability, the layer structure must typically have sufficient defibrillation resistance. This is relevant when the subject receives an electrical shock from a defibrillator and the electrodes of the electrode patch each detect a strong electrical signal and / or are generally electrically exposed to the shock. In such a scenario, the electrode patch must be configured, for example, not to overheat or otherwise be damaged, as this could be harmful to the patient (e.g., by burning his / her skin). For example, the breakdown voltage of, for example, the insulating layer of the layer structure must not be exceeded. Also, the electrode patch must return to a state where it can accurately remeasure the subject's electrical signal as quickly as possible. This is sometimes referred to as defibrillation overload recovery.

[0026] Again, in increasing the compactness of known electrode patch designs, defibrillation durability and overload recovery may be adversely affected.

[0027] On the other hand, the solution disclosed herein helps to resolve these conflicts of interest as follows: by providing the conductive tracks in multiple layers, the size and in particular the footprint of the layer structure can be reduced, for example, compared to placing the tracks next to each other in one common layer. This is particularly effective when the tracks are stacked on top of each other, according to the above-mentioned embodiment, thereby reducing, for example, the width and, as a result, the footprint of the layer structure.

[0028] However, the increased thickness possibly resulting from increasing the number of layers may be acceptable, for example more acceptable than the increased footprint. In other words, the increased thickness may not be considered as unnecessarily reducing the compactness of the layer structure, since the compactness is preferably related to the size of the surface area of ​​the subject occupied by the layer structure. This footprint limitation may also be favorable from a packaging perspective and / or reduce the area of ​​potential skin irritation. Also, a smaller footprint on the subject's body will collect less stress during movement and will give less noise while the signal is being measured. A smaller footprint will also result in less skin irritation on the subject's body.

[0029] Also, layered structures that are large in size, especially in terms of their footprint, can be difficult to apply and require two or more people to do so, whereas compact ones such as those disclosed herein can be easier to apply by one person without additional assistance or additional adhesive taping, which can be particularly relevant when medical personnel are operating under stress and time pressure.

[0030] Other advantageous effects result from the possibility of providing a limited footprint and generally reduced size connector, for example, configured to connect with an external device for signal transmission. Prior art layer structures having only one main layer to accommodate their conductive paths usually connect their multiple conductive paths next to each other (i.e., in a common plane) to the connector. Therefore, the connector also has a large footprint, which is usually stiffer than the rest of the patch, making it uncomfortable to wear and difficult to attach to the patient's body. A large connector can make it difficult or even impossible to place it on the patient's body due to its increased need for available free space.

[0031] Alternatively, some prior art solutions use multiple connectors distributed over the plane of the electrode patch. These are difficult to apply and connect. The present solution preferably has only one connector. Compared to the prior art, generally smaller connectors and / or a single connector can be used.

[0032] It has also been determined that large single planar / layer electrode patches may be difficult to manufacture with existing manufacturing equipment and / or involve increased manufacturing costs, whereas the present multi-layer structure, due to its limited layer size, is likely manufacturable with existing manufacturing equipment (e.g., by stacking conventionally manufactured and sized layers on top of each other), while at the same time increasing the functionality and total number of conductive pathways distributed across multiple layers.

[0033] Moreover, by distributing the conductive paths over several layers, the cross section of the paths can be increased without increasing the footprint of the layer structure (for example, compared to their respective cross sections when placed in one common layer). In this way, the ohmic resistance of the paths is reduced, and higher currents and voltages can be applied to the paths. Thus, high efficiency and precision can be achieved while increasing compactness.

[0034] Furthermore, by placing the conductive paths in different layers, the distance between them can be increased, which, for example, increases defibrillation resistance. Also, a larger volume of material (e.g., constituted by an intermediate layer) can be placed between them, which can improve electrical and / or thermal insulation in both the lateral and longitudinal directions. Further advantageous shielding effects are described below.

[0035] As a result, the disclosed multi-layer structure offers the possibility of a compact structure that is still sufficiently resistant to defibrillation impulses. In other words, compactness does not compromise defibrillation resistance, since multiple layers and conductive paths can still be present. Also, the generally multiple conductive paths may increase resolution, particularly in terms of detecting biosignals, compared to existing single-layer structures of similar size and footprint.

[0036] The increased distance and / or the provision of a dedicated intermediate layer also reduces the risk of localized heat concentrations, which could theoretically result from an (external) defibrillation pulse that is partially detected by the electrodes of the layer structure. Likewise, an improved electrical and / or thermal insulation allows higher voltages to be applied and can help to shield the conductive path from noise. The latter is particularly effective when, according to preferred examples, a dedicated shielding layer is provided, which shields the conductive path against external electromagnetic disturbances. However, due to the preferred reduction in the footprint of the solution disclosed herein, this shielding layer may have a limited size, which reduces costs.

[0037] Any shielding layer may be passive (e.g., not electrically driven or powered) or active (e.g., electrically driven or powered), in which case, for example, so-called driven guards may be used.

[0038] The layer structure may be an electrode patch and may be configured to detect and / or capture electrical signals in general and biological signals in particular of a living body. The layer structure may therefore be used, for example, for multi-lead ECG. To do so, the layer structure may comprise a number of electrodes. Each of at least some of the conductive paths of the layer structure may be electrically connected to at least one electrode to carry a supplementary signal, for example to a connector or other part of the layer structure.

[0039] The electrodes may comprise or be formed by the measuring points according to any of the embodiments disclosed in EP 3626158 A1. Thus, the electrodes may consist, for example, of silver or silver chloride. The electrodes may also be formed by forming a local conductive connection between the conductive layer (preferably its selected conductive path) and the analyte (for example by connecting to the surface of a layer structure that can be attached to the surface of the analyte). This may include providing a channel, recess, opening or generally free space between the conductive layer and preferably its selected conductive path in which a conductive substance (for example a gel) can be placed. However, this may include locally perforating or generally extending through or over any other layer between the respective conductive layer and the surface that is attached to the analyte. This may include extending over other conductive layers and / or intermediate layers placed in between.

[0040] The conductive layers may be constructed according to any of the embodiments disclosed in the above-referenced EP 3626158 A1. Each conductive layer may comprise a number of conductive paths with free spaces between them. The paths may cross each other or be locally electrically connected to each other. They may additionally or alternatively run away from each other and / or parallel to each other and may generally be electrically unconnected. Overall, this may be a net-like or grid-like structure of any conductive layer, the paths forming respective parts of this structure. It should be noted that any conductive layer may result in discontinuous, but may be considered to define a defined (discontinuous) layer and / or a defined stage of the layer structure. In other words, a plane or stage of the layer structure through which the conductive paths extend is said to be a conductive layer.

[0041] On the other hand, the free spaces within the conductive layer may be filled when an adjacent layer, e.g. an insulating layer, is provided and preferably laminated. Alternatively, the conductive layer may comprise a (preferably non-conductive) base layer or resin in which the conductive paths are arranged or embedded.

[0042] Each of the conductive paths of the conductive layer may have a width of 1 mm to 5 mm, preferably 2 mm to 4 mm. Each of the conductive paths of the conductive layer may have a width of at least 1 mm, preferably at least 2 mm, even more preferably at least 4 mm. Each of the conductive paths of the conductive layer may have a width of 5 mm or less, preferably 4 mm or less, more preferably 3 mm or less.

[0043] The conductive layer may comprise a conductive particle composition, preferably with an elastic polymer resin, such as polyurethane, silicone, rubber and / or polydimethylsiloxane resin. In particular, the conductive particle composition may be a silver-carbon paste. Preferably, the silver-carbon paste has at least 50% by weight of silver paste to ensure sufficient conductivity. On the other hand, the amount of silver paste in the silver-carbon paste may be reduced, for example, to less than 90% by weight, preferably less than 80% by weight, to reduce costs. On the other hand, the amount of carbon paste may be increased to maintain the conductivity of the paste even under the best enlargement envisaged. The silver-carbon paste may have 50% to 90% by weight of silver paste, more preferably 60% to 80% by weight of silver paste, even more preferably 70% by weight of silver paste. The silver paste may have a solid content of 30% to 80% by weight, preferably 40% to 70% by weight, more preferably 50% to 60% by weight. The solids may be the conductive particles of the composition and may have the form of at least one of flakes, powders, particles, microparticles, nanoparticles, nanotubes, spheres, nanowires, microwires, wires, and the like. The weight percentage of the silver-carbon paste that is not silver paste may be only carbon paste or may be carbon paste in addition to other ingredients.

[0044] The conductive particle composition may be provided by mixing at least two pastes with different functional phases, such as a silver paste and a carbon paste, each containing a polymer resin. The resins must be compatible. Alternatively, the conductive particle composition may be provided by one paste with at least one functional phase, such as only a carbon paste or only a silver paste, or by one paste with at least two different functional phases. Alternatively, the conductive particle composition may be provided by one paste with at least one conductive phase, for example a conductive polymer paste.

[0045] Although silver and carbon have been mentioned above as exemplary conductive components, in principle any conductive material may be used in place of or in addition to silver and / or carbon, such as Au, Cu and other metals, conductive polymers and / or hydrogels.

[0046] To ensure sufficient conductivity, each of the conductive layers may have a maximum resistivity of 0.005 Ωm for frequencies from DC to 200 kHz. The resistivity of each of the conductive layers is preferably less than 0.003 Ωm, more preferably less than 0.0005 Ωm, even more preferably less than 0.00001 Ωm, and even more preferably less than 0.000001 Ωm for frequencies from DC to 200 kHz.

[0047] Each of the conductive layers may be elastic, i.e., extensible, so that the conductive layers can fully maintain their conductivity even under stretching. For example, a conductive path having a width of 4 mm may still have a resistivity of less than 0.5 Ωm, preferably less than 0.1 Ωm, more preferably less than 0.05 Ωm, and even more preferably less than 0.03 Ωm when stretched longitudinally to 150% of its original length, and may still have a resistivity of less than 1.0 Ωm, preferably less than 0.75 Ωm, more preferably less than 0.5 Ωm, and even more preferably less than 0.3 Ωm when stretched longitudinally to 175% of its original length, and may still have a resistivity of less than 10 Ωm, preferably less than 5 Ωm, more preferably less than 2.5 Ωm, and even more preferably less than 1.7 Ωm when stretched longitudinally to 200% of its original length.

[0048] Also, a conductive path having a width of 2 mm may, when stretched longitudinally to 150% of its original length, still have a resistivity of less than 0.5 Ωm, preferably less than 0.25 Ωm, more preferably less than 0.1 Ωm, and even more preferably less than 0.05 Ωm, particularly when stretched longitudinally to 175% of its original length, still have a resistivity of less than 1.0 Ωm, preferably less than 0.75 Ωm, more preferably less than 0.5 Ωm, and even more preferably less than 0.3 Ωm, particularly when stretched longitudinally to 200% of its original length, still have a resistivity of less than 15 Ωm, preferably less than 10 Ωm, more preferably less than 8 Ωm, and even more preferably less than 7.5 Ωm, and even more preferably less than 5 Ωm.

[0049] Also, a conductive path having a width of 4 mm, when stretched longitudinally to a length of 150% of its original length, preferably does not increase its resistivity by more than 10,000%, more preferably not more than 7,000%, even more preferably not more than 5,000%, and even more preferably not more than 4,000%.

[0050] Also, a conductive path having a width of 2 mm, when stretched longitudinally to a length of 150% of its original length, preferably does not increase its resistivity by more than 12,000%, more preferably not more than 10,000%, even more preferably not more than 8,000%, and even more preferably not more than 6,000%.

[0051] With respect to the silver-carbon paste, it has been determined that a silver-carbon paste having a higher amount of carbon is more resistant to stretching in terms of its electrical conductivity, i.e., such a paste exhibits less increase in resistivity when stretched.

[0052] Typically, any layer of the layer structure can be homogenous, for example in terms of structure, material or texture. Preferably, the layers can include any of the materials disclosed herein, but not combinations thereof, which can support reliable and predictable deformation.

[0053] Likewise, any layer of the layer structure may be continuous, such as a closed film, coating, etc., or discontinuous, such as a discontinuous structure, pattern, film, coating, etc., provided only in some areas of a plane. It is therefore clear that the layers described above and below of the layer structure according to the invention are not necessarily present in all areas of the layer structure. For example, only some of the layers may be provided in the area of ​​the layer structure where the electrodes are formed. Furthermore, there may be areas of the layer structure where all of the defined layers are provided.

[0054] The number of conductive layers in the layer structure and / or the total number of layers may be in the range of, for example, 2 to 300, preferably 2 to 100 or 2 to 50. The number of conductive paths in each layer may be in the range of, for example, 1 to 300, preferably 1 to 100 or 1 to 50.

[0055] Any layer of the multilayer structure, and in particular the conductive layer, may have a thickness of, for example, 0.5 μm to 2000 μm, preferably 1 μm to 1000 μm or 10 μm to 100 μm.

[0056] The conductive path width may be, for example, in the range of 0.1 mm to 10 mm, preferably 0.5 to 5 mm.

[0057] The distance between the conductive paths arranged on a common layer may, for example, be in the range of 0.1 mm to 20 mm, preferably 0.5 mm to 15 mm. It has been found that an undesirable excess of the breakdown voltage can be reliably avoided at a distance of more than 0.5 mm, for example more than 1 mm or at least 2 mm. On the other hand, the more intermediate layers are present and / or the thicker or more insulating these layers are, the closer the conductive paths can be positioned relative to each other. Also, in order to achieve a compact design, the distance between the conductive paths may be less than 20 mm, preferably less than 15 mm, even more preferably less than 10 mm.

[0058] Furthermore, the generally suitable radiation transparency of any conductive layer may be adjustable by varying or selecting the conductive particle composition. For the exemplary silver-carbon paste, the higher the amount of carbon paste, the higher the radiation transparency of the silver-carbon paste. However, for example, if the polymer resin contains conductive silver particles, a conductive layer made entirely of silver paste may be sufficiently radiation transparent, and the conductive layer is relatively thin. For example, thin refers to a thickness of at least less than 100 μm, preferably less than 5 μm, and more preferably less than 25 μm. Such a thin conductive layer may be achieved by providing the respective composite deposits.

[0059] Additionally or alternatively, the layer structure may comprise either a carrier layer (e.g. providing a hardening and / or stabilizing effect, preferably forming the outer layer of the layer structure, e.g. facing away from the subject) and a descriptive layer (e.g. visualizing at least one of a plurality of measurement points and / or at least one instruction and / or at least one reference point to assist in a predetermined positioning of the layer structure relative to the subject).

[0060] There may be multiple intermediate layers. There may be an adhesive layer forming or exposable to an outer surface of the layer structure. The adhesive layer may be configured to adhere to a surface of a subject to secure the layer structure thereto.

[0061] Typically, the layer structure and / or any of the layers that it comprises may be transparent and / or radiation-transparent. At least 90% of the area of ​​the layer structure may be radiation-transparent, for example due to the radiation transparency of the optional adhesive layer and / or the radiation transparency of any of the conductive layers. Preferably, at least 95% of the area of ​​the layer is radiation-transparent, more preferably at least 97%. Even more preferably, 100% of the area of ​​the layer structure, i.e. the entire area, is radiation-transparent. The area of ​​the layer structure refers to the surface area of ​​the layer structure, since the layer structure preferably has a substantially flat shape or configuration.

[0062] The term radiolucent as used herein refers to a material or composite that is substantially or completely transparent to electromagnetic, magnetic and / or electric fields and / or radiation employed in typical (medical) imaging procedures such as X-ray or MRI in a manner and to an extent similar to that of soft human tissue, e.g. muscle tissue. In other words, the layer structure according to the invention allows X-ray or MRI electromagnetic radiation to pass through it without blocking it, and thus does not appear interfering in the X-ray or MRI image. Thus, the layer structure according to the invention can be worn by a patient during X-ray or MRI treatment without adversely affecting said treatment. In particular, radiolucency can mean that the layer structure, i.e. the radiolucent material, does not darken the images of typical hospital X-ray (RTG) and / or fluoroscopy and X-ray film taken during angiography and / or other cardiac / neurological / radiological procedures (diagnostic and / or therapeutic) by more than 60% of the image brightness. An exemplary system for a typical hospital X-ray can be a Siemens Artis Zee with exemplary settings of lamp voltage between 40 kV and 70 kV and lamp current between 8 mA and 12 mA. This maximum darkening must not be exceeded so that the practitioner can still assess and evaluate the image. In particular, radiolucency can mean that the layer structure, i.e. the radiolucent material, does not darken the image of a typical hospital X-ray (RTG) by more than 50% of the image brightness, preferably by 40% or less, more preferably by 30% or less, even more preferably by 28% or less, even more preferably by 18% or less, even more preferably by 5% or less. The less the image brightness is obscured by the layer structure, the better the acquired image can be assessed and evaluated by the practitioner. In other words, radiation transparency preferably means that the layer structure, i.e., the radiation transparent material, does not attenuate radiation by more than 40.0 μGy / min, preferably not more than 40.0 μGy / min, preferably not more than 30.0 μGy / min, more preferably not more than 26.0 μGy / min, and even more preferably not more than 23.0 μGy / min.In other words, radiolucency preferably means that the ratio of the dose of radiation attenuated by the layer structure, i.e., the radiolucent material, to the total dose of radiation emitted during the procedure does not exceed 5%, preferably does not exceed 3.5%, more preferably does not exceed 2%, even more preferably does not exceed 1.7%, and even more preferably does not exceed 1.5%.

[0063] It should be understood that the exact radiation transparency may vary in different regions of the layer structure depending, for example, on the number, thickness and type of layers present in a particular region. For example, the radiation transparency of the adhesive layer may be greater than the radiation transparency of the conductive layer.

[0064] In an embodiment, the layer structure may further comprise a descriptive layer as mentioned above, which visualizes at least one of the possible electrodes and / or at least one instruction and / or at least one reference point to assist in a predetermined positioning of the layer structure on the subject. The descriptive layer may be arranged on the carrier layer, i.e. between the carrier layer and the conductive layer. Preferably, the descriptive layer or the descriptive and conductive layers are the only non-transparent layers of the layer structure. As a result, when applying the layer structure to the subject, the user can see the descriptive layer through the optional carrier layer and can see the subject through the carrier layer and, for example, the adhesive layer (and preferably any conductive layer), thereby being able to match parts of the descriptive layer to predetermined marks, reference points, anatomical features, etc. For example, the intercostal and sternal lines may be used as reference points, thereby preventing common errors such as placing the V1 / V2 electrodes in the second intercostal space instead of the fourth intercostal space. Thus, positioning is simplified and the layer structure can be positioned more accurately and more quickly. Improved positioning also increases the reproducibility and consistency of measurements made with the layer structure.

[0065] Preferably, at least 80% of the layer structure (with respect to its surface area) may be at least 15% to 90% optically transparent, preferably at least 40% optically transparent, i.e. have a light transmittance of 15% to 90%, preferably at least 40%, for visible light of wavelengths between 370 nm and 700 nm.

[0066] Also, the layer structure and any combination of layers thereof, particularly those not including the conductive layer, may have a light transmittance of 15% to 90% for visible light having a wavelength of 370 nm to 700 nm, more preferably 30% to 70%, and even more preferably 40% to 55%. More preferably, the light transmittance of such a combination of layers for light having a wavelength of 680 nm is greater than the light transmittance for light having a wavelength of 550 nm. In particular, the light transmittance of such a combination of layers for light having a wavelength of 680 nm is 1% to 15% higher than the light transmittance for light having a wavelength of 550 nm (i.e., the percentage of the light transmittance for 680 nm = the percentage of the light transmittance for 550 nm + 1% to 15%), preferably 3% to 10% higher, and more preferably 5% to 8% higher. Preferably, the light transmittance of such a combination of layers for light having a wavelength of 680 nm is 20% to 90%, more preferably 30% to 80%, even more preferably 40% to 60%, and even more preferably 45% to 55%. The intermediate layer may have a refractive index in the range of 0.7 to 2.5, preferably 1.0 to 1.8, more preferably 1.2 to 1.6, and even more preferably about 1.4.

[0067] The stretchable properties of the layer structure aid in the rapid and precise attachment of the layer structure to the surface of a subject. For example, the layer structure can be stretched (e.g., while already partially attached to the surface of the subject) to better adjust to the shape of the surface and / or to precisely cover a desired area of ​​that surface. Thus, the layer structure can be used for a variety of subject sizes and shapes.

[0068] To support the stretching of the layer structure, each of its layers, including the conductive layer, is preferably stretchable as well. However, elastic stretching, i.e. reversible elastic deformation, is generally preferred. This is different from, for example, providing a non-rigid flexible layer structure that deforms under its own weight but is not stretchable, much less elastically stretchable. This is also true, for example, of a conventional flexible circuit board. The disclosed layer structure can also be generally non-rigid and flexible. It can, for example, comprise a flexible circuit board that is at least somewhat elastically stretchable.

[0069] A generally suitable elasticity of the layer structure or its individual layers reduces negative motion artifacts and improves positioning relative to the subject. The optional elastic adhesive layer may be longitudinally extensible in the range of 1% to 1000%, preferably 100% to 900%, more preferably 200% to 800%, even more preferably 300% to 500%, even more preferably 350% to 450%. The optional elastic conductive layer may be longitudinally extensible in the range of 1% to 1000%, preferably 100% to 900%, more preferably 200% to 800%, even more preferably 300% to 500%, even more preferably 350% to 450%. The elasticity of both the adhesive layer and the conductive layer allows optimal application and adaptation to the shape and dimensions of the subject, for example to the patient's body. Thus, the layer structure is available for different subject sizes and shapes.

[0070] In an embodiment, the optional adhesive layer has a compressibility of 1.0 to 600.0 N / mm 2 , preferably 2.0 to 500.0 N / mm 2 , more preferably 3.0 to 250.0 N / mm 2 , and more preferably 3.0 to 20.0 N / mm 2 The optional conductive layer may have an elastic modulus of 1.0 to 100.0 N / mm 2 , preferably 2.0 to 50.0 N / mm 2 , more preferably 3.0 to 25 N / mm 2 , and more preferably 5.0 to 15.0 N / mm 2The elastic modulus of the adhesive layer may be higher than that of any conductive layer, and in particular the ratio of the elastic modulus of the adhesive layer to that of any conductive layer may be in the range of 0.6 to 10.0, preferably in the range of 0.6 to 6.0 or 1.0 to 6.0, more preferably in the range of 0.6 to 1.3, and even more preferably in the range of 1.0 to 1.3.

[0071] Reliable elastic stretching can be achieved if at least one layer (e.g., the middle layer) of the layer structure comprises a deformable polymer. For example, said layer can be configured as or include a thermoplastic polymer layer, in particular a polymer layer such as at least one of a TPU layer, a PET layer, a silicone layer, etc. Alternatively or additionally, any layer of the layer structure may comprise other materials such as paper or cloth. The layer may be a nonwoven, a woven, a film, a foam, a coating, etc. The polymer layer may also be siliconized. This can be achieved, for example, by casting a polymer resin onto a siliconized paper during manufacture. Such paper will also determine the roughness of the layer. Exemplary roughnesses (tested according to ISO4287:1999) of the resulting layer may be in the range of 1-1.5 μm Pa, 1.2-1.7 μm Pq, 6.4-6.9 μm Pz, and 3.6-4.1 Pp.

[0072] The intermediate layer may comprise a material different from that of the conductive layers. As will be described in more detail below, the intermediate layer may have different electrical properties compared to the conductive layers, for example it may be less conductive or may not be conductive at all (i.e. it may be insulating). The intermediate layer may be attached to at least one of the conductive layers by lamination or by printing or usually depositing the conductive layer (particularly the conductive paths that make up said layer) onto the intermediate layer.

[0073] The intermediate layer can be provided, for example, by inserting it as an additional layer, for example, made of paper, impregnated paper, plastic film (for example, polypropylene film) or plastic plate. Alternatively, it can be provided as a special coating (for example, parylene) deposited (for example, printed, cast, spin-coated, vacuum-deposited) directly on the conductive layer. A second conductive layer can then be provided (for example, printed) on top of the intermediate layer. Also, examples of methods for producing layer structures are given below.

[0074] The adhesive constituted by the optional adhesive layer may be provided, for example, as an adhesive film deposited on a support layer constituted by the adhesive layer. The adhesive may be elastic (stretchable). The adhesive may be an inherent property of the adhesive layer. The adhesive may be provided locally in certain areas of the adhesive layer or may cover substantially the entire surface of the adhesive layer. The adhesive may be printed, dispensed, sprayed or deposited by other methods. The adhesive may be skin-friendly to avoid skin irritation and to increase the comfort of the layer structure. In particular, the adhesive may be biocompatible. Preferably, the ratio of cell survival of cells in contact with the adhesive during a cytotoxicity test, tested according to DIN EN ISO 10933-10:2010, may be higher than 0.7, preferably higher than 0.8, more preferably higher than 0.9.

[0075] As mentioned above, the present improvement in defibrillation resistance of the layer structure may include or be specified as defibrillation overload recovery capability. This capability may require, for example, that after a defibrillation pulse is applied to the subject (and, for example, after a specified time interval has elapsed), the electrodes of the layer structure, preferably not connected to another voltage source, must not have a residual potential above a specified threshold. For example, a pair of electrodes connected to the subject and / or at least indirectly connected to each other (e.g., by a conductive gel applied to the surface of the subject, i.e., a gel-gel connection) may have a maximum absolute polarity potential of 100 mV after a defibrillation attempt. The potential difference may be measured for several seconds after the defibrillation attempt, for example, 5 seconds. In this way, it is ensured that the signal measured by the electrodes actually originates from the subject and is not dominated by the residual potential difference caused by a conventional defibrillation overload.

[0076] Here, for example, any gel-to-gel connected electrodes will provide the desired defibrillation overload recovery capability and / or can be tested to confirm that such defibrillation overload recovery capability is present.

[0077] Additionally or alternatively, defibrillation resistance may include and / or be specified as the ability to maintain a stable residual polarity potential between the electrodes of the layer structure after a defibrillation attempt. This may include, for example, that the rate of change of said potential does not exceed a specified threshold (e.g., during a specified time span following a defibrillation attempt). For example, the rate of change may be limited to ±1 mV / sec within a time interval of a few seconds, e.g., 30 seconds, after measuring said polarity potential. This allows, for example, for accurate automatic reset of the entire ECG system after a defibrillation attempt. Typically, it may help to limit undesired effects occurring in the ECG system, such as baseline drift or baseline deviations above an acceptable threshold (e.g., less than 0.5 mV) from the pre-defibrillation state.

[0078] Additionally or alternatively, defibrillation resistance may include and / or be specified as the electrode pairs described above having a maximum impedance after a defibrillation pulse of, for example, 10 kΩ, preferably 5 kΩ, and more preferably 3 kΩ, which may be measured at a 10 Hz setting of the ECG system.

[0079] A possible test setup for determining whether a layer structure meets any or each of the above requirements comprises exposing the layer structure (e.g. comprising at least one electrode pair of the above type, e.g. mounted on a suitable test surface) to at least one discharge capacitor or to a number of successive discharge capacitors. In a suitable example, at least four successive discharge capacitors are provided, which can be successively discharged after time intervals of, for example, up to 2 minutes, preferably up to 1 minute, more preferably up to 30 seconds (e.g. 15-30 seconds). Any of the above characteristics (potential difference, its rate of change, impedance) can be determined after each discharge of one of the capacitors. A suitable capacitor is, for example, a 10 μF capacitor, charged to 200 V and discharged through a series electrode pair, preferably with an ohmic resistance of 100 Ω.

[0080] According to a preferred embodiment, the intermediate layer is an insulating layer, or in other words is non-conductive. This may help to provide the desired electrical insulation between the conductive layers. When coated with other conductive materials constituting a shield / guard, it may also provide a shielding effect against undesired effects of, for example, electromagnetic radiation. The intermediate layer may also act as a spacer and / or thermal insulator, thereby improving, for example, the defibrillation resistance of the layer structure.

[0081] Typically, the electrical insulation between each layer, preferably between at least one pair of adjacent conductive layers, may be at least 10 GΩ of insulation resistance, preferably at least 15 GΩ, more preferably at least 18 GΩ, even more preferably at least 20 GΩ, even more preferably at least 50 GΩ, and even more preferably at least 100 GΩ of insulation resistance. This insulation may be provided by at least one intermediate layer.

[0082] Additionally or alternatively, the breakdown voltage of the intermediate layer may be at least 100V, preferably at least 500V, even more preferably at least 1 kV, even more preferably at least 2 kV, even more preferably at least 2.5 kV, even more preferably at least 4 kV, even more preferably at least 6 kV.

[0083] According to a preferred embodiment, the layer structure comprises at least one layer configured to provide a shielding effect for at least one of the first and other conductive layers, the shielding effect being one of the following: For example, forming a conductive connection between at least one conductive path of a conductive layer and a structure external to said layer; For example, electrostatic coupling between at least one conductive path of a conductive layer and a structure external to said layer; For example, electromagnetic induction between at least one conductive path of a conductive layer and a structure external to said layer, the conductive path acting for example as a secondary winding or secondary structure that can be excited (without shielding effect) by an external primary winding or primary structure, Radio frequency interference, which may be detected by the conductive paths of the conductive layers and add noise to the electrical signals carried by them, Environmental influences such as humidity, temperature, dust or gas The present invention relates to limiting (or preferably completely inhibiting) at least one of the following:

[0084] To achieve any of the above shielding effects, the layer may have appropriately selected material properties. In the case of the first four shielding effects, these properties may be or relate to electrical properties of the layer, such as its ohmic resistance or electromagnetic transmittance. For shielding against environmental influences, the layer may have low thermal conductivity and / or be water-tight, air-tight or dust-tight. For example, the layer may meet an IP (Ingress Protection) rating of any of 1 to 8 for water-tightness, an IP rating of any of 5 to 6 for dust-tightness and / or provide a seal especially against dust sizes of 1 μm to 100 μm.

[0085] In one example, the layer may have a shielding factor of 1 to 40 dB (about 1.26 to 10,000 times) against radio waves, more preferably 5 to 35 dB (about 3.16 to about 3,162 times), and even more preferably 10 to 30 dB (10 to 1,000 times). In general, to achieve shielding against electromagnetic radiation, the layer preferably has a low ohmic resistance, which may be comparable to the ohmic resistance of the conductive layer (e.g., not differing by more than 20% or not differing by more than 10%).

[0086] The layers may be either conductive layers or intermediate layers. Intermediate layers may, for example, provide a non-conductive shielding effect and / or thermal insulation. Conductive layers, on the other hand, may at least partially shield each other against electromagnetic induction, for example due to having a low ohmic resistance.

[0087] Thus, in a preferred example, the layer providing the shielding effect is formed by one of the first and other conductive layers and provides a shielding effect with respect to the respective other of the first and other conductive layers. Additionally or alternatively, the shielding may be provided by any conductive layer or conductive part constituted by the layer structure, for example a layer or part not provided for carrying a vital signal. In one example, such a shielding layer or part may extend at least partially perpendicular to the layer structure, for example extending along or surrounding a conductive layer that is shielded in a vertical direction.

[0088] Additionally or alternatively, there may be other layers and in particular dedicated shielding layers providing any of the abovementioned shielding effects. Such layers may be arranged between the conductive layers of the layer structure or between any of the outermost conductive layers and the respective adjacent outer surface layer. In one example, the shielding layers are constituted by or form the respective outer surface layer. By providing a dedicated shielding layer, the desired shielding effect can be achieved particularly reliably.

[0089] According to a preferred embodiment, at least one of the first and the other conductive layers does not have any active electrical components or comprises more passive electrical components than active electrical components. According to the established definition, a passive electrical component may be a component that provides its desired function without the need for an external power source (e.g., it may be a resistor, a transformer or a conductive path). On the other hand, an active electrical component will require an external power source and may be, for example, a transistor or a microcontroller. An active electrical component may control or correct an electrical signal using the supplied power.

[0090] Since active electrical components are usually difficult or even impossible to deform, the use of more or exclusively passive electrical components may improve elastic extensibility, which may also reduce the manufacturing costs of the layer structure (e.g., due to the absence of a relatively expensive microcontroller), and the layer structure may therefore be economically usable as a disposable element.

[0091] Optional aspects include that the first and the other conductive layers are conductively connected to each other. For example, at least one conductive path of the first conductive layer may be connected to a conductive path of the other layer. This may be done, for example, by forming a dedicated conductive connection in or across the intermediate layer to connect multiple measurement points to one channel and / or provide an antenna. Otherwise, the intermediate layer may be non-conductive. It may electrically isolate the conductive layers and their conductive paths from each other apart from such optional local connections. Alternatively, the respective connections may be absent and the conductive layers may be completely isolated from each other.

[0092] Additionally or alternatively, the first and other conductive layers may be conductively connected or conductively connectable to a common component, such as a connector that is conductively connected or connectable to an internal or external device. This connection may allow signals to be transferred from the conductive path to an external device via the connector. In this way, costly electrical components and especially active components (especially logic components or microcontrollers required for signal analysis) may be provided outside the layer structure. This also reduces the cost of the layer structure, which may be economically disposable.

[0093] The connector may be a radiolucent polymer-based connector. It therefore does not require removal of the electrodes for X-ray, MRI or CT examinations. The connector may also be optically transparent. The connector may be a single socket connector. In some preferred embodiments, the connector may be configured to expose the conductive paths in a direction facing away from the subject in the mounted state of the layer structure. This applies in particular to embodiments in which the layer structure comprises a carrier layer covering one of the conductive layers towards the layer structure surface facing away from the subject in the mounted state of the layer structure. The connector may be a polymer plate having conductive traces on its surface facing away from the subject in the mounted state of the layer structure. The connector is attached to the layer structure in the following manner, in which its conductive traces face and partially overlap the conductive paths of the conductive layers, more precisely one conductive trace of the connector partially overlaps only one corresponding conductive path of the conductive layers, thereby reversing the direction of the conductive paths from facing towards the subject to facing away from the subject in the mounted state of the layer structure. The conductive traces of the connector may have the same composition as the conductive layer.

[0094] By realizing all of the conductive connections of the layer structure through the conductive layer, the optional material of the electrodes (e.g., hydrogel), and the conductive traces of the connector, the layer structure can be entirely cable-free, which increases the comfort of the subject to whom the layer structure is applied. It also ensures that the electrodes are not inadvertently unplugged. Furthermore, fewer cables result in less pickup of electromagnetic interference.

[0095] In a further embodiment, the device is magnetically and / or mechanically removably connectable to the connector. The connector may be provided with one or more magnets, a snap connector, an adhesive or a clip connector and the device may be provided with a corresponding counterpart to establish a removable connection. Alternatively, the device and the connector may be a single integrated part. Preferably, the device comprises a transmitter to wirelessly transmit the signals acquired by the layer structure to a processor or an analysis unit. For wireless transmission, wireless communication such as Bluetooth, short range communication, WLAN, ZigBee, Z-Wave, LoRa and / or GPRS may be used. Alternatively, the device may transmit the signals via a cable. The device may be used for methods of automated signal interpretation. Also, continuous monitoring of the acquired signals from the layer structure to a remote device such as a smartphone, tablet, laptop, etc. may be performed by live wireless transmission.

[0096] The layer structure may be deformable, in particular bendable, which may be useful, for example, to orient the layer structure as required for connection to some connector.

[0097] According to further aspects, which may be used in layer structures constructed in different ways, but are not limited to the multi-layer design disclosed herein, for example, the conductive layers may have dedicated ends or connecting portions (e.g., conductive traces or ends and / or connecting electrodes as described above) for connecting to a connector as generally described above. These connecting portions may be oriented closer to the patient's skin when applying the layer structure than, for example, to the back surface, outer surface or substrate of the layer structure facing away from the skin. In particular, the connecting portions may be provided near, on or within the lower surface of the layer structure that will initially face the patient's skin when the layer structure is attached thereto. In this situation, the connecting portions may not be accessible from above (i.e., from the upper surface of the layer structure) in order to connect a connector thereto, for example, due to the existence of multiple intermediate layers extending between the upper surface and said connecting portions.

[0098] Nevertheless, to connect the connector, the layer structure may be configured, for example, to be at least partially bent, generally, so that at least a portion of the layer structure comprising the connecting portion may be flipped over and / or reoriented to be positioned at an increased distance to the patient's skin, which portion is not adhered to the patient's skin but may be bent and moved relative thereto.

[0099] For example, an edge portion of the layer structure comprising the above-mentioned connecting portion may be bent or folded backwards and / or away from the skin (e.g., after initially extending along or parallel to the skin and / or preferably facing the skin when applying the layer structure).

[0100] The part comprising the connecting portion to which the connector is attached may be bent or even folded to such an extent that it defines a portion of the layer structure having a maximum distance to the patient's skin. For example, this portion may be bent by more than 90° with respect to an extension line parallel to the skin, for example to define a C-shape (e.g. a C-shaped cross section of at least a portion of the layer structure). Bending may also be referred to as turning over the portion of the layer structure to which the connecting portion and / or connector is attached, with a portion of the lower surface of the layer structure becoming part of the lower surface of the respective bent layer structure as a result.

[0101] In summary, a further aspect of the present disclosure relates to a conductive layer structure for application to a surface of a subject, in particular for use in medical products, comprising: At least one conductive layer having at least one conductive path, the conductive path comprising or connected to at least one connecting portion for conductively connecting the layer structure to a connector (e.g., any of the connectors of the type disclosed herein); Equipped with At least a portion of the layer structure (e.g., the portion comprising the connecting portion) is foldable so that the orientation of the connecting portion can be adjusted. This adjustment can include any of the above-mentioned features and can, for example, be the above-mentioned at least partial turning inside out of the layer structure, in particular of its edge portions.

[0102] A further aspect of the present disclosure also relates to a method of applying a conductive layer structure according to any of the aspects above or related to a multi-layer design as disclosed herein, comprising the steps of applying the layer structure to the skin of a patient, folding a portion of the layer structure with a connecting portion for connecting the layer structure to a connector (e.g., any connector of the type disclosed herein), and connecting the connector to the folded portion, where the folding (or bending) can be performed according to any of the aspects described herein.

[0103] The conductive layer structures and methods according to the above further aspects may be combined with and / or further comprise any of the features disclosed herein in relation to multi-layer designs.

[0104] According to a preferred embodiment, at least one of the layers of the layer structure comprises or is attached to (e.g. laminated with) a thermoplastic polymer material, in particular a thermoplastic polyurethane material. This may in particular be the layer to which (or formed on) the conductive layer is adhered, or the base layer of the conductive layer on which the conductive paths are provided (e.g. printed or deposited). The use of the respective material allows a suitable elastic extension to be achieved.

[0105] Preferably, at least one of the first and other conductive layers has a conductive path that is electrically connected to and / or is part of an electrode for measuring an electrical signal at (or at) the surface. In other words, at least one of the conductive layers preferably comprises or is connected to an electrode configured to capture an electrical signal of an analyte. The electrode may for example be formed by a measurement point of the conductive layer (e.g. formed by an end or an exposed part of a conductive path) and a recess extending from said point to the outer surface of the layer structure (i.e. forming a connecting channel or free space between said surface and the measurement point). Also, a conductive material such as a hydrogel may be provided in the recess and may preferably form part of the electrode.

[0106] In summary, a recess may be provided between the measurement point and the surface of the specimen, extending from the measurement point through all layers.

[0107] Additionally, any portion of a layer that is perforated by (eg, forms a wall of) a recess and / or the boundary of the recess may be considered to be part of the electrode.

[0108] However, for conductive layers that extend over one another, this can also mean that the recess extends from the upper conductive layer through the lower conductive layer toward the surface of the specimen (the terms upper and lower refer to the distance from that surface).

[0109] The recess may provide access to only one measurement point, or may be wide enough to provide access to multiple measurement points (eg, by spanning each of the multiple measurement points).

[0110] Additionally or alternatively, at least one other, preferably lower layer (e.g., lower when applied to the patient's skin) may not cover a portion of a particular conductive layer and / or measuring point or its electrodes in order to provide access to said conductive layer. In other words, not all layers must be placed perfectly congruent with respect to each other. For example, an edge or end of one layer (preferably a conductive layer) may not be covered by another (preferably lower and / or non-conductive) layer. It may protrude or overhang further to the side of the layer structure and / or have a larger footprint, rather than being covered. Thus, its measuring point and in particular its at least one electrode may be directly facing and / or connectable to the patient's skin.

[0111] In other words, according to this embodiment, at least one conductive layer may preferably have a portion (e.g., a side or edge) that is provided with at least one or more electrodes and is not shielded and / or electrically isolated from the skin by an intermediate layer. Note that each non-shielded portion may be larger than the footprint of the electrode of the conductive layer, e.g., at least two times or at least five times larger. This may define a larger non-isolated portion than that provided by the channel-like recess described herein, whose footprint is usually limited to and / or does not deviate significantly from the footprint of the electrode. Providing each large non-covered portion of the conductive layer may be an efficient manner (e.g., in terms of manufacturing) to achieve a reliable conductive connection between the skin and the conductive layer.

[0112] According to a further example, at least one conductive path of at least one of the conductive layers has at least one nonlinear or non-linear portion that can be straightened when the layer structure is stretched. This can include a curved, bent, angled, zigzag, coiled or other nonlinear portion being pulled and / or stretched to a more linear shape and thereby straightened. Figuratively, the nonlinear portion can be a reserved or recessed portion that can selectively assume a more linear shape to limit stresses (especially tensile stresses) in the conductive path when the layer structure is stretched.

[0113] Generally speaking, the above embodiment allows an adjustable positioning of the conductive path and in particular the electrodes connected thereto, in which the nonlinear section acts as a dedicated deformable, in particular linearisable, section.

[0114] The present invention also relates to a method for producing a layer structure for application to the surface of a subject, in particular for use in medical products, which method comprises the steps of: Providing a first conductive layer having at least one conductive path; providing at least one other conductive layer having at least one conductive path; providing at least one intermediate layer extending at least partially between the first and other conductive layers; Equipped with The first and further conductive layers are provided such that at least parts thereof are arranged on top of one another or in other words are stacked in a layer structure, which layer structure is preferably elastically extensible.

[0115] In general, the method may include any additional means and features for producing a layer structure according to any of the embodiments disclosed herein, and any of the teachings, explanations, aspects and variations disclosed herein in relation to the layer structure may be applicable and useful for the method as well.

[0116] The method may include attaching the provided layers to one another directly or indirectly (through at least one other layer extending therebetween), according to any of the following examples, and typically by, for example, lamination, gluing or ultrasonic welding.

[0117] According to a preferred embodiment, at least one of the first and other layers is printed or attached to the intermediate layer. For example, the intermediate layer may be provided and / or manufactured first, and then the conductive layer may be provided on its surface (e.g., on its upper or lower surface). This may reduce the overall number of manufacturing steps, for example, since a dedicated base layer does not need to be provided first to print the conductive paths of the conductive layer thereon. Instead, printing is performed directly on the intermediate layer.

[0118] In one example, the first and other conductive layers are printed or applied to opposite sides of the intermediate layer. In this way, the intermediate layer can act as a printing substrate or base for both conductive layers. Again, this can limit the overall number of layers that need to be manufactured and thereby the associated number of manufacturing steps, manufacturing costs, and resulting weight.

[0119] According to further examples, the intermediate layer is printed or applied to at least one of the first and other conductive layers (or to a layer to which the conductive layers are applied or deposited). For example, the intermediate layer may be laminated to the conductive layer (e.g., to its base layer onto which the conductive paths are printed).

[0120] Still further, a first conductive layer may be provided on a first substructure of the layer structure and a second conductive layer may be provided on a second substructure of the layer structure. The first and second substructures may be joined to form at least part of the layer structure. For example, a conductive layer may be printed on the layers forming the substructures. These layers (and thus the substructures) may then be joined (for example laminated). These layers may have to be provided in some manner on the layer structure, for example to provide a function other than acting as a substructure. They may be, for example, intermediate and / or insulating layers or adhesive layers. This may allow for rapid and reliable production, for example by having a substrate directly available for printing the conductive paths. [Brief description of the drawings]

[0121] [Figure 1] FIG. 2 is an exploded view of a layer structure according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram of a layer structure in which the layers of FIG. 1 are bonded together. [Diagram 3] FIG. 4 is an exploded view of a layer structure according to a further embodiment of the present invention; [Figure 4] 1 shows a layer structure according to an embodiment of the present invention when bent and / or turned upside down. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0122] Embodiments of the present invention will now be described with reference to the accompanying schematic drawings, in which like elements are designated with like reference numerals throughout, and in which:

[0123] 1 shows layers of a layer structure 10 according to an embodiment of the present invention. The layer structure 10 is intended to be attached to a surface (skin) 12 of a subject, for example the skin of a human patient. An exemplary layer structure 10 is an electrode patch that can be used, for example, to perform an ECG.

[0124] By way of example only, the layer structure 10 comprises three conductive layers 14. Each conductive layer 14 consists of a deposit of conductive material forming conductive paths 16. This deposit can be produced, for example, by screen printing. An area, plane or step of the layer structure 10 provided with at least one, in the example shown, conductive path 16, forms the conductive layer 14. Alternatively and as mentioned above, the conductive layer 14 can comprise a base layer in which the conductive paths 16 are positioned.

[0125] Generally, each layer of the layer structure may extend substantially perpendicular to a thickness axis T that extends perpendicular to the main faces of the layer structure 10 and / or the surface 12 of the subject.

[0126] Each conductive path 16 terminates at a measurement point 18 that is part of an electrode 20. As detailed above, the electrode 20 may include a recess 22 that extends through or across all layers between the measurement point 18 and the object's surface 12. In other words, the recess 22 may extend through or across all layers below the conductive layer 14 that includes the respective measurement point 18.

[0127] The extension of the recess to the top measurement point 18 is shown (in FIG. 1 ) by a dotted line 22. It extends over the conductive layer 14 underlying said measurement point 18 and through the layers 24, 26 on which the conductive layer 14 is disposed, to reach the surface 12 of the specimen.

[0128] Two of these layers are intermediate layers 24 disposed between two conductive layers 14. For example, at least one conductive layer 14 may be printed on one side (upper side in FIG. 1) of each intermediate layer 24, and each intermediate layer 24 may be laminated to its underlying layer on its opposite side (lower side in FIG. 1). Thus, each intermediate layer 24 may be sandwiched between two other layers, in the illustrated case between and in contact with two conductive layers 14.

[0129] By way of example only, the upper conductive layer 14 of Figure 1 may be printed on the upper intermediate layer 24 to form the first substructure 42 of the layer structure 10. And the middle conductive layer 14 of Figure 1 may be printed on the lower intermediate layer 24 to form the second substructure 44. These substructures 42, 44 may then be joined together, for example, by lamination.

[0130] The intermediate layers 24 are preferably insulating, thereby electrically insulating the conductive layers 14 from one another. They typically space the conductive layers 14 from one another and preferably act as thermal insulators.

[0131] The bottom layer 26 (in FIG. 1) of the layer structure 10 is an adhesive layer. On its outer surface facing the subject's surface 12, an adhesive is provided to secure the layer structure 10 to the patient.

[0132] 1 also shows an optional shielding layer 28 forming an outer surface of the layer structure 10 facing away from the surface 12 of the specimen. The shielding layer 28 may provide any of the shielding effects described above, but in particular electromagnetic shielding. To do so, the shielding layer 28 may comprise a conductive material and preferably an insulating material that electrically insulates the conductive material from the underlying conductive layer 14.

[0133] The layers 14, 24, 26, 28 are stacked on top of each other along axis T. This results in the merged layer structure 10 of Figure 2. This means that the conductive layers 14, and in particular their conductive paths 16, are for the most part preferably completely surrounded and thereby shielded or encapsulated by the adjacent layers 24, 26, 28. This provides protection from environmental influences such as radiation, dust and gases.

[0134] Preferably, each of the layers 24, 26 is optically transparent and / or radiation transmissive. Thus, as shown in FIG. 2, the conductive paths 16 of the underlying conductive layer 14 are visible from the outside even when stacked. It is also clear that the conductive layers 14 are aligned by being stacked or positioned on top of each other within the layer structure 10. As a result, the conductive paths 16 may cross each other, for example, when viewed from above.

[0135] Additionally, each of the layers 24, 26, and preferably also the conductive pathway 16, are elastically extensible. At least the layers 24, 26 may comprise, in large part or entirely, a homogenous polymeric material, such as TPU.

[0136] As a preferred option, a connector 30 is shown which is connected to each of the conductive paths 16 to receive electrical signals therefrom. These signals originate from the electrodes 20 to which each conductive path 16 is connected. Thus, they correspond to electrical signals at the subject's surface 12 that are detected (i.e., captured) by the electrodes 20.

[0137] The connector 30 comprises an interface for connection to an external device (not shown), which comprises further electrical components for analyzing the electrical signal. This means that the layer structure 10 is electrically passive and thus economically disposable. On the other hand, the external device may have a longer life and may for example be used for different patients. It may be selectively connected to the disposable layer structure 10 applied to each specific patient.

[0138] As a result, the disclosed layer structure 10 may generally represent an electrically passive signal bus and / or a passive signaling device, by which electrical signals may be (passively) detected and (passively) conducted to the connector 30.

[0139] In the illustrated embodiment, the conductive pathways 16 do not have a linear and / or straight course. Instead, they are routed with at least one angled portion 32 (see FIG. 1 ), which may be curved, bent, or have a zigzag shape. This portion 32 corresponds to the deformation of the conductive pathways 16 when attempting to manually adjust the position of the electrodes 20 by stretching the layer structure 10. In particular, it allows the conductive pathways 16 to have a straighter and less angled shape while limiting local stresses in the pathways 16 when a tensile force F is applied to the layer structure 10 by the practitioner.

[0140] Figure 3 shows a further embodiment based on the embodiment of Figures 1-2, therefore the same reference numerals are used. The difference with respect to the previous embodiment of Figures 1-2 above is the conductive connection of the electrodes 20 of at least a part of the conductive layer 14 to the skin 12. Furthermore, as will be explained in more detail below, the aspects of providing said conductive connection according to Figures 1-2 and 3 may be combined, i.e. provided together in one layer structure 10.

[0141] 3, rather than forming a connection preferably with the aid of a gel-filled recess 22 as illustrated in FIG 1, at least a portion of the electrodes 20 of some of the conductive pathways 16 may be exposed, i.e., not covered by any other layer, and in particular not covered by a non-conductive layer extending between said conductive pathways 16 and / or electrodes 20 and the skin 12. In other words, at least a portion of the electrodes 20 of some of the conductive pathways 16 are not electrically isolated or blocked from forming a conductive contact with the skin 12 by any other layer.

[0142] In FIG. 3, this is achieved by adjusting the overall length of at least one intermediate layer 24 below at least one conductive layer 14, where "underlying layer" refers to a location closer to the skin 12. Merely by way of example, in FIG. 3, the x-axis indicates the overall length perpendicular to the thickness axis T and thus in or parallel to the main plane of the layer structure 10. In FIG. 3, the overall lengths of the layers 24, 26 are different and decrease from layer to layer 24, 26 along the x-axis when viewed along the thickness axis T towards the skin 12. This means that the top intermediate layer 24 forms the outermost edge (with respect to the x-axis) of at least the illustrated portion of the layer structure 10. The adjacent lower intermediate layer 24 is set back along the x-axis relative to the above-mentioned upper intermediate layer 24, while the bottom adhesive layer 26 is set back even further. Instead of a setback overall length, a cutout may be provided in each layer 24, 26 defining a similar uncovered portion of the respective upper layer 24, 26.

[0143] Thus, as indicated by dotted line 23, the electrode 20 of the intermediate layer 24 is not shielded from and / or from the skin 12, and may be in conductive contact directly with the skin 12 (or with the aid of a conductive gel, not shown, applied to the skin 12). Particularly in the edge regions of the layer structure 10, this may be a suitable alternative and possibly a cheaper way of enabling a conductive connection between the skin 12 and the electrode 20 than providing a dedicated channel-like recess 22 as shown in FIG.

[0144] It should be noted that non-blocking of the general electrical contact of the electrodes 20 or of the conductive layer 14 may be provided by a cutout in an underlying non-conductive layer, which cutout preferably has a size larger than a single electrode recess, for example covering multiple electrodes 20.

[0145] Naturally, it is also possible to combine the embodiments of Figures 1 to 3, whereby some electrodes 20 are provided with recesses 22 according to Figure 1, while some electrodes 20 remain unobstructed and / or exposed according to Figure 3.

[0146] FIG. 4 illustrates an optional embodiment in which any type of conductive layer structure 10 disclosed herein may be bent and / or flipped in order to connect it to a connector 30. It should be noted that this embodiment is not limited to the multi-layer structures 10 disclosed herein (i.e., "multiple" indicates multiple conductive layers 14) and may also be implemented in the context of multi-layer structures 10 as illustrated throughout FIGS. 1-3. Accordingly, the same reference numerals as in FIGS. 1-3 are used. However, the embodiment of FIG. 4 may also be used with a layer structure 10 having only one conductive layer 14, but which may otherwise include any of the additional features disclosed herein.

[0147] Again, Figure 4 shows the skin 12 of a patient to which the layer structure 10 is applied. The layer structure 10 faces the skin 12 with its underside 50 (in Figure 4). On said underside 50 an adhesive layer 26 may be provided, similar to Figure 1. On its upper side 52, facing away from the patient's skin 12, any preferably non-conductive material and / or non-conductive layer may be provided, for example a shielding layer 28, similar to Figure 1.

[0148] By way of example only, only one conductive layer 14 is provided. The conductive pathways 16 are preferably located closer to the lower surface 50 than to the upper surface 52. They may form part of and / or extend partially within the lower surface 50. The conductive pathways 16 are preferably separated from the upper surface 52 by a (preferably non-conductive) material along their entire length. Again, the conductive pathways 16 include and / or terminate at electrodes 20 for measurement of biosignals according to any of the embodiments disclosed herein.

[0149] For reasons explained below, the layer structure 10 of Fig. 4 can be folded into a C-shape. This means that as a result of the folding, a part of the lower surface 50 does not face the skin 12 of the patient, but in fact faces away from it. Similarly, as a result of the bending, a part of the upper surface 52 faces the skin 12 of the patient. In Fig. 4, these respectively reoriented parts of the layer structure 10 are initially constituted by the leftmost part of the layer structure 10 (i.e., before bending). The reorientation can also be referred to as turning the part of the layer structure 10 inside out, e.g., so that the initial lower surface 50 forms the upper surface 52, or vice versa.

[0150] The positioning of the conductive pathway 16 closer to and / or within the lower surface 50 is shown in FIG. 4 using dotted or solid lines. Specifically, when viewed and / or oriented to be covered by the upper surface 52, the conductive pathway 16 is shielded to a greater extent, preferably by non-conductive material. In such a state or orientation, the conductive pathway 16 and the electrodes 20 are shown with dotted lines. On the other hand, when viewed and / or oriented to form the lower surface 50, the conductive pathway 16 is shielded to a lesser extent, preferably by non-conductive material, or is exposed to and / or forms a part of the lower surface 50. In such a state or orientation, the conductive pathway 16 is shown with solid lines.

[0151] 4, the conductive pathways 16 and electrodes 20 that extend through the unbent portions of the layer structure 10 that face and extend along the skin 12 are shown in dashed lines. The conductive pathways 16 that extend through the bent or everted portions of the layer structure 10 are shown in solid lines such that they face the viewer.

[0152] With this configuration, the conductive path 16 in the turned-over portion is more easily accessible for connecting the connector 30 thereto. For example, the connector 30 can be easily placed on top of the conductive path 16 and in particular its optional connecting portion 31, which would not be possible in the non-bent configuration. The connecting portion 31, which is shown only diagrammatically, can be configured as an open end or trace of the conductive path 16 and can generally provide a connection interface for conductively connecting to the connector 30.

[0153] It should be noted that the improved accessibility provided by the flip also relaxes the requirements for structural adaptation of the portions of the layer structure 10 to which the connector 30 is to be connected. For example, no portion of the top surface 52 needs to be locally removed to gain access to any of the conductive paths 16 of the unflipped layer structure 10.

Claims

1. An electrically conductive layer structure (10) for application to a surface (12) of a subject, in particular for use in medical products, comprising: a first conductive layer (14) having at least one conductive path (16); at least one other conductive layer (14) having at least one conductive path (16); at least one intermediate layer (24) extending at least partially between said first and other conductive layers (14); Equipped with At least portions of the first and other conductive layers (14) are disposed one above the other within the layer structure (10); The layer structure (10) is elastically stretchable.

2. 2. The layer structure (10) of claim 1, wherein the intermediate layer (24) is an insulating layer, and / or the first and other conductive layers (14) and the intermediate layer (24) are immovable relative to each other and / or are at least indirectly fixed relative to each other.

3. a layer configured to provide a shielding effect for at least one of the first and other conductive layers (14), the shielding effect being: forming a conductive connection; electrostatic coupling, Electromagnetic induction, radio frequency interference, Environmental influences, such as humidity The layer structure (10) of claim 1, wherein the layer structure (10) is configured to limit at least one of the following:

4. 4. The layer structure (10) according to claim 3, wherein the layer providing the shielding effect is formed by one of the first and other conductive layers (14) and provides a shielding effect for the other of the first and other conductive layers (14).

5. 10. The layer structure (10) of claim 1, wherein at least one of the first and other conductive layers (14) has no active electrical components or comprises more passive than active electrical components.

6. 2. The layer structure (10) of claim 1, wherein the first and other conductive layers (14) are conductively connected to each other and / or are conductively connected or connectable to a common component in the form of a connector (30) that is conductively connected or connectable to an internal or external device, such that signals can be transmitted from the conductive path (16) to the device through the connector (30).

7. 2. The layer structure (10) according to claim 1, wherein at least one layer of the layer structure (10) comprises or is attached to a thermoplastic polymer material, in particular a thermoplastic polyurethane material.

8. 2. The layer structure (10) of claim 1, wherein the first and other conductive layers (14) have conductive paths (16) electrically connected to and / or part of measurement points (18) for capturing electrical signals on the surface (12) of the subject.

9. 9. The layer structure (10) of claim 8, wherein a recess (22) is provided between the measurement point (18) and the surface (12) of the subject, the recess (22) extending from the measurement point (18) across all layers (14, 24, 26).

10. 10. The layer structure (10) of claim 1, wherein at least one conductive path (16) in at least one of the conductive layers (14) has at least one non-linear portion (32) that can be linearized when the layer structure (10) is stretched.

11. A method for producing an electrically conductive layer structure (10) for application to a surface (12) of a subject, in particular for use in medical products, comprising the steps of: providing a first conductive layer (14) having at least one conductive path (16); providing at least one other conductive layer (14) having at least one conductive path (16); providing at least one intermediate layer (24) extending at least partially between said first and other conductive layers (14); Equipped with the first and other conductive layers (14) are provided such that at least portions thereof are disposed one on top of the other within the layer structure (10); The layer structure (10) is elastically extensible.

12. The method of claim 11, wherein at least one of the first and other conductive layers (14) is printed or applied to the intermediate layer (24).

13. The method of claim 11, wherein the first and other conductive layers (14) are printed or applied to opposite sides of the intermediate layer (24).

14. The method of claim 11, wherein the intermediate layer (24) is printed or applied to at least one of the first and other conductive layers (14).

15. 12. The method of claim 11, wherein the first conductive layer (14) is provided on a first substructure (42) of the layer structure (10), the other conductive layer (14) is provided on a second substructure (44) of the layer structure (10), and the first and second substructures (42, 44) are joined to form at least a part of the layer structure (10).

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