Hook-type attachment layer, and a sensor strip with such an attachment layer

Abstract

A sensor strip for a sensor device, the sensor strip comprising an elongated, flexible carrier substrate and an attachment layer (20) on the carrier substrate for securing the sensor strip to an outside surface of an absorbent article. The attachment layer (20) has two elongated hook-forming areas (22a, 22b) provided on opposite sides of a central axis (A) of the sensor strip, each hook-forming area having a plurality of substantially unidirectional hooks (23a, 2b) pointing away from the central axis (A), wherein the elongated hook-forming areas are separated by a first hook-free gap (21), extending across the central axis (A). As the two hook-forming areas of the present invention have hooks pointing in opposite directions the sensor strip can be effectively entangled in the fabric of the outer surface of the absorbent article.

Description

[0001] HOOK-TYPE ATTACHMENT LAYER,

[0002] AND A SENSOR STRIP WITH SUCH AN ATTACHMENT LAYER

[0003] Field of the invention

[0004] The present invention relates to an attachment layer for attaching an object to a fibrous material.

[0005] More specifically, the present invention relates to a sensor strip comprising an elongated, flexible carrier substrate, at least one sensor element formed on the carrier substrate, and an attachment layer formed on the carrier substrate for securing the sensor strip to an outside surface of an absorbent article.

[0006] Such a sensor strip may form part of a sensor device for monitoring a state of an absorbent article, such as a diaper.

[0007] Background of the invention

[0008] In some situations, it is desirable to monitor the state of an absorbent article worn by a user, specifically to detect presence of and / or determine an amount of bodily fluid collected in the absorbent article. For example, such monitoring may be used to alert a parent or caregiver that a diaper needs to be changed, or may enable assessment when developing a nursing plan.

[0009] For the purpose of such monitoring, sensor devices have been developed which are specifically adapted to be attached to the outside of an absorbent article, such as a diaper. In order to save cost and waste, such sensor devices are preferably reusable, so that, when a diaper is changed, the sensor device can be removed from the used diaper and attached to a new diaper.

[0010] Sensor devices for absorbent hygiene articles are described e.g. in WO 2016 / 090492 and WO 2021 / 004598, and generally comprise a flexible sensor strip with one or several sensing elements to be attached to the outside surface of the absorbent article, and a processing / storage unit secured onto the sensor strip and electrically connected the sensing elements. In order to attach the sensor strip to the absorbent article, hooks of a hook-and-loop type are conventionally used. The hooks may be designed to efficiently adhere to the outside surface, which is typically made of a nonwoven fabric. There are various types of hooks suitable for this, including anchor-shaped hooks and mushroom-shaped hooks.

[0011] Although such hook-based attachment is highly efficient and easy to use, it may limit the reusability of the sensor strip. When the sensor strip is detached from the relatively fluffy surface it has been attached to, fibers (also referred to as lint) from the non-woven fabric tends to be stuck in and between the hooks, gradually reducing the fastening performance of the hooks. After a large number of detachments the sensor strip may become difficult to reattach.

[0012] Further, the design of the hooks unfortunately makes it difficult to successfully remove the lint, at least without a significant and time-consuming effort. As a result, the sensor device may need replacement sooner than would otherwise be the case.

[0013] It is noted that the above-mentioned sensor devices is only one application where repeated reattachment of objects to a fibrous material may be required. There is thus a general need for an improved hook-type attachment layer for such applications.

[0014] General disclosure of the invention

[0015] It is an object of the present invention to mitigate the above problems, and to provide an (hook-type) attachment layer which enables repeated attachment of an object to a fibrous material, such as a woven, knitted, felted or nonwoven material. Further, it is an object of the present invention to provide an attachment layer which facilitates removal of any lint which has stuck to the attachment layer. One specific object of the invention is to enable repeated attachment of a sensor strip of a sensor device on an absorbent article.

[0016] According to a first aspect of the invention, these and other objects are achieved by an (hook-type) attachment layer for attaching an object to a fibrous surface, wherein the attachment layer has two hook-forming areas provided on opposite sides of a central axis of the attachment layer, each hook-forming area having a plurality of substantially unidirectional hooks pointing away from the central axis, wherein the hook-forming areas are separated by a first hook-free gap extending across the central axis.

[0017] Hook-and-loop type attachment systems, having patches of substantially unidirectional hooks, are known, and disclosed e.g. in WO201 5 / 178706. However, such attachment systems are designed to provide only (or at least dominantly) a shear force in one direction. For example, in the mentioned document WO2015 / 178706, the unidirectional hook-and-loop patches are used to prevent the two sides of a belt to slide against each other. The attachment system in WO2015 / 178706 provides a very limited attachment force in a direction out of the contact plane.

[0018] As the two hook-forming areas of the present invention have hooks pointing in opposite directions (away from the central axis, and towards the outer edges of the sensor strip) the hooks can be effectively entangled in the fabric of the outer surface of the absorbent article. After such entanglement, the attachment layer (and any object it is provided on) will be attached to the fibrous substrate, in a hook-and-loop manner, also in a direction out of the contact plane.

[0019] As the hooks are substantially unidirectional, any lint which is caught in the hooks may be more easily removed with a simple stroking motion in the direction of the hooks, e.g. with a brush or even just the palm of your hand. Two strokes from the center of the sensor strip towards either edge will typically be sufficient to remove substantially all fibers from the hooks. The attachment layer is then again ready to be attached to a fibrous surface.

[0020] In order to facilitate the removal of lint, the hooks preferably have any “one-way” design, as opposed to more complex hook shapes or even mushroom shapes. They may be bent, but may also have a straight form. Such “straight hooks” are here referred to as “barbs”. According to Wikipedia, a “barb” is something that stands out with a sharp point obliquely or crosswise to something else. One well-known example of a barb is the sharp bit that points backward in an arrow, fishhook, etc., to prevent it from being easily extracted. In a similar manner, the substantially unidirectional barbs pointing away from the central axis, will be caught in the fabric of the outer surface and prevent the sensor strip from sliding along the outer surface in the direction of the barbs. The simple geometry of barbs is specifically advantageous for avoiding lint being stuck in the attachment layer, and for easy removal of such lint.

[0021] In some embodiments, the attachment layer is elongated and flexible, and the two hook-forming areas are also elongated and extend along the elongated attachment layer. This design of the attachment layer has advantageous properties for ensuring satisfactory fastening performance.

[0022] In some embodiments, the hooks in each hook-forming area are substantially parallel, and oriented normal to the longitudinal extension of the sensor strip. Such fully unidirectional arrangement will be particularly advantageous with respect to lint removal.

[0023] However, in other embodiments, the hooks in each hook-forming area may exhibit a slight angular spread, preferably less than 90 degrees. The angular spread may improve the ability to get attached to the outer surface, as fabric contraction in several directions may contribute to hooks getting stuck in the fabric.

[0024] For example, the hooks in each hook-forming area may be formed in subareas distributed along the sensor strip, wherein each subarea includes a set of parallel hooks, and wherein hooks in adjacent subareas are oriented at an angle with respect to each other.

[0025] The attachment layer may be formed by a sheet of plastically deformable material, preferably a polymeric material, such as silicone, polypropylene, polyethylene, polyethyleneterephtalate, etc.. The hooks may then be formed in the sheet by punching or other appropriate technique. The attachment layer may alternatively be formed in a molding process, utilizing a moldable material, where the hooks are formed in the molding process. A second aspect of the invention relates to a sensor strip for a sensor device for monitoring a state of an absorbent article, the sensor strip comprising an elongated, flexible carrier substrate, at least one sensor element formed on the carrier substrate, and an attachment layer according to the first aspect formed on a first major surface of the carrier substrate for securing the sensor strip to an outside surface of an absorbent article.

[0026] The attachment layer according to the present invention is highly suitable for attaching a flexible, elongated object like the sensor strip of a sensor device. The sensor strip is an excellent example of an object that advantageously can be reattached a large number of times to a fibrous material.

[0027] For attaching the sensor strip to an absorbent article, often a simple pressure will be sufficient. Pressing the strip into the soft absorbent article will cause the outer surface fabric to stretch on either side of the strip (along the hooks), and when released the fabric will strive to contract and return to its normal extension (against the hooks). When the fabric contracts, the hooks of both hook-forming areas will be caught in the fabric, but in opposite directions, effectively preventing easy removal of the strip. In some situations, additional motion of the sensor strip may be advantageous for satisfactory attachment. For example, it may be useful to alternatingly press the sensor strip sideways, across its longitudinal extension. The sideways motion will cause additional stretching of the fabric, causing further entanglement.

[0028] For facilitating sideways motion of the strip, to thereby help in the process of attaching the strip to the fabric, the strip may be provided with a grippable ridge on the opposite side of the hook-forming areas. When the strip is attached to an absorbent article, the ridge will thus face away from the article and be easily grippable by a user.

[0029] A third aspect of the invention relates to a sensor device comprising a sensor strip according to the second aspect and an electronics unit secured to the sensor strip, wherein the electronics unit houses processing circuitry electrically connected to the sensor elements and configured to control the sensor elements to detect a property indicative of the state of the absorbent article.

[0030] In some embodiments, the detected property is impedance. Detecting impedance is an advantageous way to detect moisture and wetness in a contact-free manner.

[0031] The electronics unit may further house a wireless interface for communicating externally of said sensor device. Such wireless communication is advantageous when the sensor device is used for monitoring the state of absorbent articles.

[0032] In some embodiments, the electronics unit extends beyond respective edges of the sensor strip. In this case, the electronics unit, on a surface cooriented with the first major surface, may be provided with additional hookforming areas provided on opposite sides of the central axis, wherein each additional hook-forming area includes a plurality of substantially unidirectional hooks pointing away from the central axis, and wherein the additional hookforming areas are separated by a second hook-free gap centered around the center axis.

[0033] A wider electronics unit enables placement of hook-forming areas further away from the center axis, thereby improving the ability to be attached to the outer surface.

[0034] The second hook-free gap may be wider than the first hook-free gap.

[0035] Brief description of the drawings

[0036] The present invention will be described in more detail with reference to the appended drawings, showing currently preferred embodiments of the invention.

[0037] Figure 1 is a perspective view of a diaper provided with a sensor device according to an embodiment of the present invention.

[0038] Figure 2 is a perspective view of the sensor device in figure 1 .

[0039] Figure 3 is a plane view of the sensor strip of the sensor device in figure 1-2.

[0040] Figure 4 is a cross sectional view of the sensor strip in figure 3. Figure 5 shows the attachment layer of a sensor strip according to a first embodiment of the present invention.

[0041] Figure 6 shows the attachment layer of a sensor strip according to a second embodiment of the present invention.

[0042] Figure 7 shows the attachment layer of an electronics unit and sensor strip according to an embodiment of the present invention.

[0043] Detailed description of preferred embodiments

[0044] Figure 1 illustrates an absorbent article 1 , here a diaper, provided with a sensor device 2 configured to detect some physical property of the diaper 1 , such as the presence or a level of moisture in the diaper 1 , in order to thereby monitor a state of the diaper 1 . For example, the sensor device 2 may be configured to provide an indication of when it is time to replace the diaper 1. The sensor device 2 includes a sensor strip 3, which is releasably attached to the outer fabric 4 of the diaper, and an electronics unit 5. The sensor device 2 is shown in more detail in figure 2.

[0045] With reference to figure 3, the sensor strip 3 includes an elongated, flexible carrier 11 , made of e.g. a flexible printed circuit board (flex-PCB) or another appropriate polymeric material. A set of sensor elements 12 are provided on a major surface 11 a of the carrier 11 , which major surface 11 a is intended to face the absorbent article 1 . In the illustrated case, each sensor element 12 includes a pair of electrically conducting electrodes 13a, 13b, provided on either side of a central axis A of the flexible carrier 11 . The electrodes 13a, 13b are connected by conducting tracks 14, also provided on the carrier 11 . The electrodes and tracks can be applied on the flexible carrier 11 e.g. by printing. In the case of a flex-PCB with a conducting layer, the electrodes 13a, 13b and the conducting tracks 14 can be formed by etching.

[0046] The electronics unit 5 houses processing circuitry 15 which is electrically connected with the sensor elements 12 via conducting tracks 14. The processing circuitry 15 is configured to drive the sensor elements 12 and to receive measurement data indicative of the state of the diaper 1 . The electronics unit 5 may further include a wireless interface 16, for communicating externally of the sensor device 2, e.g. for signaling with a supervising system (not shown). The electronics unit preferably also houses a power supply for driving the sensor elements.

[0047] With the illustrated sensing elements 12, the processing circuitry 15 can be configured to detect an electrical impedance between the electrodes 13a, 13b, and based on the detected impedance determine a level of moisture. It is noted that other types of sensor elements 12, and other detection principles, may also be implemented. Potential properties that may be detected include presence of a particular chemical, pH level, and others.

[0048] As shown in figure 4, the sensor strip 3 is provided with a protective coating 17 on the side of the carrier 11 opposite the sensing elements 4, i.e. the side intended to face the garments of the user. The protective coating 17 serves to protect the sensor strip 3, and to provide an adequate surface texture of the sensor strip 3. Suitable materials for the protective layer 17 may be liquid impermeable. They also preferably provide mechanical resistance e.g. against scratching.

[0049] In certain embodiments, the protective layer may be folded around the edges of the carrier 11 to provide a soft rounded edge. In certain embodiments (as shown in figure 4), the protective layer 17 may be slightly wider than the carrier 11 but not folded around the edges, the portions of the protective layer extending beyond the edges of the carrier protecting the carrier . Examples of suitable materials for the protective layer include silicone layers, thermoplastic elastomers and polyurethane-based foams, for example Dermabak® F110 from Rogers Corporation, which is a poly urethane-based foam membrane.

[0050] On the side facing the absorbent article 1 (the diaper in this case), the sensor strip 3 is provided an attachment layer 20. The attachment layer is configured to allow releasable attachment of the sensor strip 3 to the outside fabric 5 of the diaper 1 , in the illustrated case a non-woven fabric. The attachment layer 21 needs to be transmissive to electromagnetic radiation, in order not to interfere with the detection by the sensor elements 12. In the illustrated example, the protective layer 17 wraps around the carrier 11 , such that the attachment layer 20 may be attached to the folded- over portions 18 of the protective layer 17 to completely seal the sensor strip 3.

[0051] In the illustrated example, the sensor strip 3 is also formed with a central ridge 19, which may facilitate sideways movement of the sensor strip 3 during attachment.

[0052] The attachment layer 20 has two elongated hook-forming areas 22a, 22b, each having a plurality of substantially unidirectional hooks 23a, 23b formed thereon. The hooks are of the hook-and-loop-type, but with a defined direction of engagement. Preferably, the hooks are “straight hooks”, i.e. they form straight points pointing in one direction. Such a straight hook resembles the barb of a fishing hook.

[0053] The hook-forming areas 22a, 22b are formed on opposite sides of the central axis A, and the hooks 23a, 23b of each respective hook-forming area 22a, 22b point away from this central axis.

[0054] Between the hook-forming areas 22a, 22b is formed a hook-free gap 21 , extending across the central axis A. For reasons of symmetry, the gap 21 may be centered around the axis A. The width of the gap may typically be in the range of from 0.5 cm to 5 cm, depending on the total width of the attachment layer. In certain embodiments, the width of the hook free gap may be from 0.5 to 2 times the width of each of the hook-forming areas.

[0055] In the embodiment in figure 5, the unidirectional hooks of each hookforming area 22a, 22b are all substantially parallel, and oriented normal to the central axis. In other examples, the hooks may have a slight angular spread, e.g. up to 90 degrees, preferably only up to 45 degrees, or only up to 30 degrees.

[0056] In another embodiment, illustrated in figure 6, the hook-forming areas 22a, 22b each includes a plurality of subareas 24a, 25a, 26a and 24b, 25b, 26b arranged along the sensor strip 3. Each subarea 24a-b, 25a-b, 26a-b has a plurality of substantially parallel hooks 27, and the hooks in adjacent subareas are oriented at an angle with respect to each other. As shown in figure 6, the hooks 27 in subarea 24b point in direction B1 , the hooks 27 in adjacent subarea 25b point in direction B2, while the hooks in adjacent subarea 26b point in direction B3. Direction B2 is normal to the central axis, while directions B1 and B3 form angles ai and 02, with direction B2.

[0057] The attachment layer 20 and the hooks may be manufactured in various ways. In the embodiment shown in figure 5, the attachment layer 20 is formed of a sheet of a plastically deformable material, such as a thermoplastic or thermosetting polymeric material, for example silicone, and the hooks 23a, 23b may then be punched out of the sheet. Many other manufacturing methods are possible, including molding or 3D printing.

[0058] In figure 7 is illustrated that also the back side (the side facing the absorbent article) of the electronics unit 5 may be provided with hook-forming areas 28 and hook-free gap 29 therebetween. The hook-forming areas 28 may be formed by simply attaching an attachment layer similar to attachment layer 20 (but different shape). In principle, the hook-forming areas 28 may also be formed (e.g. punched) directly into the surface of the electronics unit 5.

[0059] As the electronics unit 5 in the illustrated case is wider than the sensor strip 3, the gap 29 may be wider than gap 21 .

[0060] The detailed description has been related to the second and third aspects of the invention, i.e. the use of an attachment layer on a sensor strip of a sensor device. It is noted that the attachment layer of the present invention has numerous other beneficial applications, as will be appreciated by the skilled person.

[0061] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. For example, a sensor strip and sensor device according to the present invention may advantageously be fitted also on other absorbent articles than diapers.

Claims

CLAIMS1. An attachment layer (20) for attaching an object (2) to a fibrous material, c h a r a c t e r i z e d in that said attachment layer (20) has two hook-forming areas (22a, 22b) provided on opposite sides of a central axis (A) of the attachment layer (20), each hook-forming area having a plurality of substantially unidirectional hooks (23a, 23b) pointing away from the central axis (A), wherein said hook-forming areas are separated by a first hook-free gap (21 ), extending across said central axis (A).

2. The attachment layer (20) according to claim 1 , wherein the hooks (23a, 23b) are formed as barbs pointing away from the central axis (A).

3. The attachment layer (20) according to any one of the preceding claims, wherein said attachment layer (20) is elongated and flexible, and wherein said two hook-forming areas (22a, 22b) are elongated and extend along the elongated attachment layer (20).

4. The attachment layer (20) according to any one of the preceding claims, wherein the hooks (23a, 23b) of each hook-forming area are substantially parallel, and oriented normal to the central axis (A).

5. The attachment layer (20) according to any one of the preceding claims, wherein the hooks (23a, 23b) of each hook-forming area have an angular spread less than 90 degrees.

6. The attachment layer (20) according to claim 5, wherein the hooks in each hook-forming area includes a plurality of subareas (24a, 25a, 26a; 24b, 25b, 26b) distributed along the sensor strip, wherein each subarea includes a set of parallel hooks, and wherein hooks in adjacent subareas are oriented at an angle with respect to each other.

7. The attachment layer (20) according to any one of the preceding claims, wherein the attachment layer (20) is formed by a sheet of plastically deformable material, such as a thermoplastic polymeric material or a thermosetting polymeric material.

8. The attachment layer (20) according to claim 7, wherein the hooks are formed in the sheet by punching.

9. A sensor strip (3) for a sensor device (2) for monitoring a state of an absorbent article (1 ), said sensor strip (3) comprising: an elongated, flexible carrier substrate (11 ), at least one sensor element (12) formed on the carrier substrate, and an attachment layer (20) according to any one of the preceding claims formed on a first major surface (11a) of the carrier substrate for securing the sensor strip to an outside surface of an absorbent article (1 ).

10. The sensor strip (3) according to claim 9, further comprising a protective layer (17) provided on a side opposite the attachment layer (20).11 . The sensor strip (3) according to claim 9 or 10, further comprising a grippable ridge (19) on a side opposite the attachment layer (20).

12. A sensor device (2) for monitoring a state of an absorbent article (1), said sensor device comprising: a sensor strip (3) according to one of claims 9-11 , and an electronics unit (5) secured to the sensor strip, said electronics unit housing processing circuitry (15) electrically connected to said sensor elements and configured to control the sensor elements to detect a property indicative of the state of the absorbent article (1 ).

13. The sensor device according to claim 12, wherein the detected property is impedance.

14. The sensor device according to claim 12 or 13, wherein the electronics unit (5) further houses a wireless interface (16) for communicating externally of said sensor device (2).

15. The sensor device according to any one of claims 12 - 14, wherein the electronics unit (5) extends beyond respective edges of the sensor strip, and wherein the electronics unit (5), on a surface co-oriented with the first major surface, is provided with additional hook-forming areas (28a, 28b) provided on opposite sides of said central axis (A), wherein each additional hook-forming area includes a plurality of substantially unidirectional hooks pointing away from said central axis (A), and wherein said additional hook-forming areas are separated by a second hook-free gap (29) centered around said central axis (A).

16. The sensor device according to claim 15, wherein the second hook-free gap (29) is wider than the first hook-free gap (21 ).

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