Skin sensor element

Abstract

A skin sensor element has a number of sensor layer which comprise a contact elastomer layer, a transfer elastomer layer, an electrically conductive support layer and a connecting layer for fastening to another object. The contact elastomer layer material and the transfer elastomer layer material are different from each other.

Description

[0001] Skin sensor element

[0002] The invention relates to a skin sensor element with which the electrical skin resistance is determined or which is used to stimulate the skin or underlying tissue layers by applying an electrical voltage, according to the preamble of claim 1.

[0003] WO 2018 / 050172 A1 discloses a wearable electrode integrated into a garment. The electrode consists of several superimposed layers, of which the outer layer in contact with the skin is an electrical contact layer made of polyurethane, followed by an electrical transmission layer made of polyamide, which is connected to a power connector.

[0004] JP 2014 025180 A discloses trousers with a stretch sensor that is applied to the fabric of the trousers using an elastic adhesive. The stretch sensor registers stretches in the fabric of the trousers. The sensor signals from the stretch sensor are transmitted to an external device via a transmitter that is also integrated into the trousers. US 2016 / 0302724 A1 discloses a belt with integrated length sensors, the sensor signals from which are transmitted to a control unit in a buckle of the belt. A motor is integrated into the buckle, which tightens or loosens the belt depending on the sensor information.

[0005] DE 10 2006 053 949 A1 describes a safety belt in a vehicle with an integrated sensor, whereby the sensor signals are used to control a belt retractor.

[0006] DE 10 2008 042 554 A1 discloses an elastic chest strap for monitoring a patient's respiration. A strain sensor is sewn onto the chest strap. This sensor comprises two deformable electrode layers forming a capacitor, with an insulating layer of elastomer material between them. The electrode layers are connected to an evaluation unit on the chest strap.

[0007] DE 10 2019 114 185 B4 discloses a tactile sensor element with several layers arranged directly one above the other: a substrate layer as the first layer, electrode layers applied thereon laterally offset in a plane as the second layer, a spacer layer applied thereon as the third layer, and a measuring layer applied to the spacer layer as the fourth layer. A further, fifth layer can be applied to the measuring layer, which fulfills a protective function and is made of an electrically non-conductive elastomer material.

[0008] EP 3 932 657 B1 describes a connector assembly arranged in a fabric for muscle stimulation or as a sensor. The connector assembly has a multilayer structure and comprises a base material, a conductive fabric connected thereto, an elastic and compressible conductor connected thereto, and a textile covering fabric. The electrical conductor is arranged between the conductive fabric and the covering fabric.

[0009] The invention is based on the object of creating a skin sensor element with simple measures which can be used, for example, in an item of clothing, a bandage or a belt.

[0010] This object is achieved according to the invention with the features of claim 1. The subclaims specify expedient developments.

[0011] The skin sensor element according to the invention can be used to determine vital parameters such as, for example, electrical skin resistance or to stimulate the skin by applying an electrical voltage. The skin sensor element can be used, for example, in a garment such as an undergarment or an outer garment, for example by integration into a textile carrier material of the garment or by connection to a textile carrier material of the garment, for example by means of a hook-and-loop fastener.

[0012] The skin sensor element could also be used in a bandage or a belt. In either case, the skin sensor element is suitable for use on a user's body. In the case of a belt, it could be used, for example, to attach a helmet or other body protection such as elbow pads, knee pads, or a corset. The bandage could be an open bandage that is fastened using a suitable closure mechanism with straps or clips, or a closed, circumferential bandage in a ring or cylinder shape that is pulled onto an arm or leg, for example.

[0013] The skin sensor element has several sensor layers that are stacked one above the other or one above the other in such a way that the layer planes of the sensor layers are offset parallel to one another. The individual sensor layers overlap one another and can be stacked congruently if they have the same or approximately the same base area. If the base area varies, the sensor layers partially or completely overlap.

[0014] A first, outer sensor layer forms a contact elastomer layer for immediate, direct contact with the skin. The contact elastomer layer consists of an elastomer material with specific material parameters that ensure, in particular, a slightly sticky consistency of the contact elastomer layer that adheres to the skin. The contact elastomer layer is electrically conductive in order to transmit an electrical impulse to the skin.

[0015] The contact elastomer layer is followed by a second, separately formed sensor layer, which consists of another, likewise electrically conductive elastomer material and forms a transfer elastomer layer. The elastomer material of the transfer elastomer layer differs from the elastomer material of the contact elastomer layer in at least one material parameter. In particular, in contrast to the contact elastomer layer, the transfer elastomer layer is less or not sticky and can optionally have a higher electrical conductivity than the contact elastomer layer.

[0016] The transmission elastomer layer is followed by a third sensor layer, which acts as an electrically conductive carrier layer and supports the two elastomer layers. The carrier layer serves both in a version for measuring electrical skin resistance and, in a version for stimulating the skin, as a transmitter of the voltage pulse. For example, electrical power cables can be connected to the carrier layer to determine a voltage drop between two power cables to measure electrical skin resistance and to generate a voltage potential to stimulate the skin.

[0017] The electrically conductive carrier layer is followed by a fourth sensor layer, a connecting layer, which serves to attach the skin sensor element to another object that is not part of the skin sensor element, for example to connect it to a foreign layer of a piece of clothing, a bandage or a belt. The connecting layer can, for example, be designed as a bonding layer, via which bonding to a foreign layer, in particular a textile layer, is possible. The skin sensor element designed in this way has the advantage that during production of the skin sensor element the two elastomer layers can be produced in a simple manner by applying the elastomer materials.Each elastomer layer is optimally adapted to the respective task: the contact elastomer layer can adhere to the skin and the transfer elastomer layer has an optimized electrical conductivity, which ensures a very good electrical transfer between the transfer elastomer layer and the carrier layer.

[0018] In an advantageous embodiment, the contact elastomer layer and the transfer elastomer layer lie directly on top of one another. This embodiment can be easily manufactured, for example, by applying the elastomer in two layers of different elastomer materials via a nozzle. Another advantage is that electrical impulses can be transmitted directly between the contact elastomer layer and the transfer elastomer layer.

[0019] In a further advantageous embodiment, the skin sensor element comprises exclusively the contact elastomer layer, the transmission elastomer layer, the electrically conductive carrier layer, and the connecting layer as sensor layers. The skin sensor element is thus composed of four superimposed sensor layers; no further sensor layers are present.

[0020] In an alternative embodiment, it is also possible for one or more additional sensor layers to be present in the skin sensor element. These additional sensor layers are located between two of the sensor layers that the skin sensor element must include: the contact elastomer layer, the transfer elastomer layer, the electrically conductive carrier layer, and the connecting layer. If necessary, two or more additional sensor layers can be arranged between two of the mandatory sensor layers.

[0021] According to yet another advantageous embodiment, the contact elastomer layer consists of an elastomer material with higher adhesiveness than the transfer elastomer layer.

[0022] This design ensures that the contact elastomer layer adheres slightly to the skin, maintaining skin contact even when the wearer moves. The contact elastomer layer possesses a certain degree of stickiness, allowing surface skin contact even when the wearer moves. At the same time, it is possible to remove the skin sensor element from the skin without discomfort and without damaging the contact elastomer layer or any other sensor layer.

[0023] According to an advantageous embodiment, the elastomer materials of the contact elastomer layer and the transfer elastomer layer are provided with different additives. The desired properties of the contact elastomer layer and the transfer elastomer layer can be achieved via the additives. However, the elastomer base material can be identical for the contact elastomer layer and the transfer elastomer layer.

[0024] The additives advantageously have different carbon contents. It is particularly advantageous for the carbon content in the contact elastomer layer to be lower than in the transfer elastomer layer, thereby achieving both increased adhesiveness in the contact elastomer layer and increased electrical conductivity in the transfer elastomer layer.

[0025] In another advantageous embodiment, at least one electrical conductor is connected to the electrically conductive carrier layer. The electrical conductor(s) can be used to connect the skin sensor element to a voltage source and / or an evaluation unit. The electrical conductor(s) can be passed through a recess in the connecting layer, which allows the electrical conductor(s) to be continued into the adjacent layer, for example, a textile layer.

[0026] The invention further relates to an article provided with a skin sensor element as described above. The article is, for example, a piece of clothing, a bandage, or a belt, for example in a protective helmet.

[0027] Yet another aspect of the invention relates to a method for producing a skin sensor element as described above. In the method, the elastomer material of the transfer elastomer layer is applied to the electrically conductive carrier layer, and then the elastomer material of the contact elastomer layer is applied thereon, wherein the elastomer materials differ in at least one material parameter. The elastomer can be applied using an appropriately configured nozzle, optionally using a 3D printing process. The elastomer is preferably applied with a constant thickness of the elastomer material in the direction of travel of the nozzle and in the transverse direction thereto. The elastomer of the contact elastomer layer is applied at a time offset from the elastomer application of the transfer elastomer layer. The time offset can be dimensioned such that the elastomer material of the transfer elastomer layer has already cured slightly.

[0028] Further advantages and expedient embodiments can be found in the further claims, the description of the figures and the drawings, which show a skin sensor element with a total of four sensor layers, wherein the skin sensor element is suitable for use on a fabric patch which is, for example, part of an item of clothing, a bandage or a belt.

[0029] Fig. 1 shows the layered structure of an electrode designed as a skin sensor element 1 with several parallel sensor layers 3, 4, 5, 6 designed as layers. The skin sensor element 1 can be used as a sensor in a fabric or textile layer 2, for example, for recording vital parameters, but also for muscle stimulation. The textile layer 2 is part of an article of clothing, a bandage, or a belt to be worn on the body.

[0030] The skin sensor element 1 comprises a total of four sensor layers 3, 4, 5, 6, of which the uppermost sensor layer 3 and the lowermost sensor layer 6 each form an outer sensor layer in the layered structure of the skin sensor element 1. All sensor layers 3, 4, 5, 6 are the same size or approximately the same size and lie congruently on top of one another in such a way that two directly adjacent sensor layers touch one another. The layer planes of the sensor layers 3, 4, 5, 6 are parallel to one another.

[0031] The first, uppermost sensor layer 3 forms a contact elastomer layer for contact with the skin. This is followed by a connecting elastomer layer 4 as the second sensor layer, which is in surface contact with the contact elastomer layer 3. Both elastomer layers 3, 4 are electrically conductive, but they differ in the elastomer material. The contact elastomer layer 3 exhibits higher adhesiveness than the underlying connecting elastomer layer 4. The base elastomer material used in both elastomer layers 3, 4 can be identical, but the material properties differ due to an added additive, which in both layers 3, 4 can be a carbon-based additive, but with a different carbon content. The outer contact elastomer layer 3 is provided with an additive that has a lower carbon content than the additive in the connecting elastomer layer 4.The higher adhesiveness of the contact elastomer layer 3 means that this sensor layer adheres slightly to the skin upon contact and sticks slightly. However, the adhesiveness is only strong enough to allow the skin sensor element 1 to be removed at any time without causing unpleasant sensations on the skin or damage to the skin sensor element 1. The carbon content in the contact elastomer layer 3 makes this layer 3 electrically conductive. Due to the higher carbon content, the underlying connecting elastomer layer 4 is even more electrically conductive. Layer 4 rests on the carrier layer 5, which is also electrically conductive and can be, for example, a textile, a fleece, a film, or a conductive paint.On the underside of the carrier layer 5, the fourth and final, lowest layer is a connecting layer 6, with which the skin sensor element 1 can be connected to a piece of clothing, a bandage, or a belt. The connecting layer 6 is designed, for example, as a bonding layer, via which bonding to a layer of the piece of clothing, the bandage, or the belt is possible, for example, to a textile layer.

[0032] Recesses 7 are formed in the connecting layer 6, through which an electrical conductor is passed, which is connected to the electrically conductive carrier layer 5. The electrical conductor 8 is led to a voltage source or an evaluation unit.

[0033] The figure shows the sensor layers 3, 4, 5, 6 in an exploded view. In the finished skin sensor element 1, the sensor layers 3, 4, 5, 6 are stacked directly on top of one another and firmly connected to one another, resulting in a strip-shaped structure of the skin sensor element 1 that is flexible and can therefore adapt to the shape of the skin surface. To produce the skin sensor element 1, for example, a 3D printer can be used, via which the two elastomer layers 3 and 4 are applied to the carrier layer 5 using a print head. For this purpose, the connecting elastomer layer 4 is first applied to the carrier layer 5. Then, if necessary after a curing time of the elastomer material of the connecting elastomer layer 4, the elastomer material of the contact elastomer layer 3 can be applied directly to layer 4.

Claims

Patent claims 1. A skin sensor element comprising a plurality of sensor layers (3, 4, 5, 6) stacked one above the other in such a way that the layer planes of the sensor layers (3, 4, 5, 6) are parallel to one another, characterized in that a first, outer sensor layer forms a contact elastomer layer (3) for contact with the skin and consists of an electrically conductive elastomer material, wherein a second, separately formed sensor layer (4) is connected to the contact elastomer layer (3), which consists of a further electrically conductive elastomer material and forms a transfer elastomer layer (4), wherein the elastomer material of the transfer elastomer layer (4) differs from the elastomer material of the contact elastomer layer (3) in at least one material parameter, and wherein a third sensor layer (5) is connected to the transfer elastomer layer (4), which is designed as an electrically conductive carrier layer (5),and that the electrically conductive carrier layer (5) is adjoined by a fourth, outer sensor layer (6), which is designed as a connecting layer (6) for attaching the skin sensor element (1) to an object., 2. Skin sensor element according to claim 1, characterized in that the contact elastomer layer (3) and the transfer elastomer layer (4) lie directly on one another.

3. Skin sensor element according to claim 1 or 2, characterized in that the skin sensor element (1) has as sensor layers exclusively the contact elastomer layer (3), the transfer elastomer layer (4), the electrically conductive carrier layer (5) and the connecting layer (6).

4. Skin sensor element according to one of claims 1 to 3, characterized in that the contact elastomer layer (3) consists of an elastomer material with higher adhesiveness than the transfer elastomer layer (4).

5. Skin sensor element according to one of claims 1 to 4, characterized in that the elastomer materials of the contact elastomer layer (3) and the transfer elastomer layer (4) are provided with different additives.

6. Skin sensor element according to claim 5, characterized in that the additives have different carbon contents.

7. Skin sensor element according to claim 6, characterized in that the carbon content in the contact elastomer layer (3) is lower than in the transmission elastomer layer (4).

8. Skin sensor element according to one of claims 1 to 7, characterized in that at least one electrical conductor (8) is connected to the electrically conductive carrier layer (5).

9. Skin sensor element according to claim 8, characterized in that the electrical conductor (8) is passed through a recess (7) in the connecting layer (6).

10. A garment comprising a skin sensor element (1) according to one of claims 1 to 9.

11. Bandage with a skin sensor element (1) according to one of claims 1 to 9.

12. Belt, for example in a protective helmet, with a skin sensor element (1) according to one of claims 1 to 9.

13. A method for producing a skin sensor element (1) according to one of claims 1 to 9, wherein the elastomer material of the transfer elastomer layer (4) is applied to the electrically conductive carrier layer (3) and then the elastomer material of the contact elastomer layer (3) is applied to the transfer elastomer layer (4).

Images