HK1190910A - Connector device for use in negative-pressure therapy of wounds - Google Patents

Description

Connection device for use in negative pressure treatment of wounds

Technical Field

The invention relates to a connection device for use in the negative pressure therapy of wounds, having a guide means that can be acted upon by a negative pressure and having a planar, i.e. plate-shaped, negative-pressure-tight carrier means for the guide means, which is held in a negative-pressure-tight manner on the carrier means, wherein the carrier means can be placed on a negative-pressure bandage that covers the wound and is closed in a manner sealed off from the atmosphere, so that the guide means can communicate with the wound space through the guide means and the carrier means and at least one opening in the negative-pressure bandage.

Background

In its transient history, negative pressure therapy of wounds, in particular deep and therefore therapeutically problematical wounds (a priori), is of increasing importance. Negative pressure therapy is understood to mean the pressure-tight or negative pressure-tight closure of a body region or wound area exposed to the surrounding atmosphere by means of a device which is described in more detail below with respect to the environment (i.e. the atmosphere in which we live and breathe), wherein a pressure lower than atmospheric pressure, i.e. a negative pressure with respect to the atmosphere, can be applied and maintained for a long time in the closed wound area in a manner which is also described in more detail. Thus, when a region of negative pressure is referred to herein, it is understood to be a region of pressure typically between 0 and 250mmHg (mm hg) below ambient atmospheric pressure. This has been shown to be promoting for wound healing. For negative pressure closure, a negative pressure bandage is provided, which may comprise, for example, a pressure-tight or negative pressure-tight foil layer, which is typically bonded to the intact body region around the wound, so that in this way a sealed closure can be achieved. In order to achieve and maintain a negative pressure at the wound space starting from a device for generating a negative pressure (i.e. a negative pressure pump in the broadest sense), a guide device which can be acted on with a negative pressure can be used in the system for negative pressure therapy of wounds mentioned here, which guide device interacts with a negative pressure bandage by means of a connecting device in order to bring the negative pressure to or into the wound space. A connecting device of the type mentioned at the outset is known, for example, from WO2006/052338A2 or DE102009060596A 1. In order to mount the connection device to the wound bandage, up to now an additional adhesive foil covering the carrier device has been used mainly, which is not expedient in all cases.

Disclosure of Invention

The invention is based on the object of producing a connection device of the type described at the outset, in which the mounting and sealing with respect to the wound bandage can be carried out with technically and economically reasonable effort and in a manner that is friendly to handling.

In the case of a connecting device of the type mentioned, this object is achieved according to the invention in that: an adhesive layer having at least three sub-layers is arranged on the wound-facing side of the carrier device, which adhesive layer comprises a central carrier sub-layer, a first adhesive sub-layer held at the carrier sub-layer and facing the carrier device, and a second adhesive sub-layer held at the carrier sub-layer and facing away from the carrier device (i.e. facing the negative pressure bandage), and which adhesive layer is designed such that it does not block the at least one opening in the carrier device.

The design of the connection device of the invention proves particularly convenient, since the adhesive layer can typically be fixed in an ideal flat dimension for the flat, wound-facing side of the planar carrier device, whereas from this an additional adhesive foil has to cover the configuration of the carrier device or the carrier device and thus form an additional third dimension, which makes the sequential process of mounting or adhering the connection device towards the wound-facing upper side of the wound bandage more difficult in the actual handling due to the formation of folds. Another advantage of the connection device of the invention results from the following situation: the use of different materials, for example silicon on the one hand and polyurethane on the other hand, for the planar carrier material and the wound bandage is typical, so that the adhesion of the adhesive foil cannot be optimally determined for both materials. This is not the case in the connection device according to the invention, since the first adhesive layer can be optimally selected for the material of the carrier device independently of the second adhesive layer, and the second adhesive layer can be optimally designed for the material of the wound bandage independently of the first adhesive layer. It has then proven to be advantageous if the first adhesive part-layer and the second adhesive part-layer consist of adhesive materials having different adhesive properties, so that they can be selected in accordance with the specific material of the carrier device or of the negative pressure bandage.

In this case, it has proved particularly advantageous if the carrier device consists of silicon and the first adhesive part-layer comprises a silicon adhesive, at least as a main constituent. In addition, it may prove to be advantageous for the second adhesive part-layer to comprise an acrylate adhesive, at least as a main constituent. The acrylate adhesive imparts an outstanding adhesion to the polyurethane surface. Optimal adhesion to the wound dressing can then likewise be achieved with a polyurethane surface.

According to a further inventive concept, it has proven advantageous if the adhesive area of the first adhesive part-layer facing the carrier device and/or the adhesive area of the second adhesive part-layer facing the negative pressure bandage is less than 45cm²Especially less than 40cm²Especially less than 35cm²Especially less than 30cm². It has been shown that a much smaller adhesive area is required in the connection device in the case of an adhesive material which is optimally defined for achieving the adhesive effect with the adhesive partner (Haftpartner), i.e. the material of the carrier device or of the wound bandage. Here, the area value is a one-side projected area of the contact side surface concerned, that is, a size of a viscous flat area of the first or second adhesive sub-layer.

It has also been shown that a substantial improvement in the adhesion between the connecting device and the negative pressure bandage can be achieved by using an optimized adhesive layer. For the standardized comparison, the adhesion was tested against smooth and pre-degreased steel sheets. In this case, the connecting devices are glued flat to the smooth surface of the steel sheet in their respective desired design, wherein a drawing machine is used according to standard EN29073-3 (ISO 9073-3) and a movable drawing clamp of the drawing machine is connected in a clamping manner to the guide leading out of the carrier device and the guide is then forced at a drawing angle of approximately 0 degrees relative to the steel sheet (i.e. in the direction of the guide leading out of the carrier device). That is, the steel plate and carrier assembly are oriented vertically in the tensile tester. The steel sheet is a steel sheet according to DIN EN 1939. The distance of the carrier device to the tensioning point is 20 cm. The stretching of the movable stretching nip was carried out at a speed of 300 mm/min. The known connecting device already causes a detachment from a steel plate or a previously known adhesive foil covering the carrier device, i.e. a damage, at a tensile force of less than 40N, but the connecting device designed according to the invention is able to withstand a tensile force of at least 40N without damage.

It has proven advantageous to use an adhesive layer in the connection device according to the invention, the first adhesive part-layer of which is designed such that it has a peel force (vermitetlte) of 25 to 40N/100mm (thickness of the first adhesive part-layer 100 mm) relative to the steel plate imparted by this first adhesive part-layer, and/or the second adhesive part-layer of which is designed such that it has a peel force (vermitetlte) of 70 to 85N/100mm (thickness of the second adhesive part-layer 100 mm) relative to the steel plate bonded by this second adhesive part-layer. The adhesive layer is tested as such, i.e. without being connected to a carrier device. This peel force was determined according to ASTM test method D3330M, with a residence time of 31 minutes, a tensile angle of 180 degrees (peel orientation) and a tensile speed of 300 mm/min. The test was performed at 22 degrees celsius and 50% relative air humidity. These values can be achieved in an advantageous manner when the first adhesive sub-layer comprises a silicon adhesive or the second adhesive sub-layer comprises an acrylate adhesive.

It has proven to be expedient in terms of production technology if the first and second adhesive part-layers have the same planar dimensions in projection in their plane of extension, i.e. coincide in projection, and in particular have the same dimensions as the carrier part-layer. In the last case, all layers are then designed to coincide. This embodiment has proven to be particularly advantageous since the adhesive layer can in this case be produced from an annular, planar material strip which is coated on both sides with adhesive material, so that only the sections required for the adhesive layer have to be cut or punched out.

The adhesive layer can be produced in a particularly advantageous manner starting from a double-sided adhesive tape, wherein a section of the double-sided adhesive tape is separated and correspondingly configured in size and shape and then applied to the wound-facing side of the carrier device.

The adhesive layer is preferably applied with its first carrier layer directly to the wound-facing side of the carrier device.

It has also proven advantageous for the first and second adhesive sub-layers to have a thickness of 20 to 400 micrometers.

In an advantageous manner, the intermediate carrier layer can be a planar material with a textile bonding effect (textile bond), such as, for example, a knitted, crocheted or woven fabric, or can be a plastic foil, a metal foil or a composite thereof.

It has also proven to be advantageous if the adhesive layer extends over the entire side of the carrier device facing the wound, wherein at least one opening is cut out in the carrier device for the purpose of negative pressure communication.

It is also conceivable and advantageous for the adhesive layer to extend frame-like around at least one opening in the carrier device. In this case, the planar size of the adhesive layer is also substantially smaller than the planar size of the wound-facing side of the carrier device. However, it has also proven to be advantageous if the planar dimensions of the adhesive layer are at least 50% of the area of the wound-facing side of the carrier device.

It has also proven to be advantageous if the second adhesive part-layer is covered by a detachable protective part-layer, which is preferably designed in two parts and preferably has a gripping tab and/or a region which projects from the second adhesive part-layer and can be gripped.

In order to make the connection device itself comfortable or less painful for the patient when applied or in contact with it, it is further proposed that the guide device is designed to be flexible and flat and is fixed with the planar side toward an upper side of the carrier device facing away from the wound.

It has furthermore proved to be advantageous if the guide means, in a wound-side longitudinal section having at least 70% of its projected area perpendicularly to the carrier means, is connected to the carrier means in a non-releasable and planar manner for the intended use, and the guide means here consist of a flexible elastomer material preferably having a shore a hardness of at most 60. It has also proved to be preferred if the composite produced from the guide device and the carrier device has a thickness dimension of at most 7 mm.

The guide means are not designed as tubular with a substantially circular cross-section, but have a flat shape with a width dimension substantially greater than a thickness dimension. This together with the material selection results in a soft guiding means which proves to be more comfortable for the patient when a contact pressure is applied to the connecting device or the guiding means. This results in fewer point-like loads which can naturally lead to pain and are very problematic in particular in the case of new wounds which are sensitive to pain. Furthermore, due to the flat design, there is little back hooking (Hinterhakens) or hold-on (V) hooking) The danger of (2). When the guide means in its longitudinal section fixed to the carrier means is connected in a planar manner to the planar carrier means with at least 70% of its projected area perpendicular to the carrier means (wherein the opening or openings are added to the wall of the guide means for this purpose), the pressure load is distributed over a large-area of the wound bandage, which plays a very advantageous role in terms of the problems set out above. Preferably, the guide device is connected to the carrier device in the longitudinal section for fastening by at least 80%, in particular at least 90%, and also in particular at least 95%, of its projection area perpendicular to the carrier device.

The width dimension of the flat guide which has already been mentioned is at least 10mm, in particular at least 15mm, and also in particular at least 18mm, and in particular at most 30mm and also in particular at most 25 mm.

The elastomeric material constituting the guide means preferably has a shore a hardness of 5-60, in particular 10-60, in particular 15-50, in particular 15-40 and also in particular 15-35. As already mentioned above, the shore a hardness is determined according to DIN53505 of 8 months of 2000 and at 23 degrees celsius on a plate-like, flat and smooth test specimen having a thickness of 6mm as described in the standard. According to a preferred embodiment of the invention, the guiding means are designed to be silicon-based.

Since the flat and flexible guide device is used to introduce the negative pressure into the wound space and, if appropriate, to introduce the cleansing liquid or cleansing gas and to discharge the wound exudate, i.e. preferably has only a communicating function forming a channel, it is proposed that the guide device is not formed in a layered manner from a plurality of components or layers, but rather is formed continuously in a tubular manner, i.e. in one piece in the circumferential direction, as viewed in cross section, from a single material, although it has a flat configuration.

It has also proven to be advantageous if the guide device has an internally formed device, in particular formed in one piece from the material of the guide device, which serves to prevent the guide device from collapsing when an underpressure is applied. Such means for avoiding collapse of the guide means can be provided directly in the case of a hose-like guide means in the sense described above. Such means for avoiding collapse may be formed, for example, by a plurality of ribs or projections. In a development of the inventive concept, it has proven advantageous if they extend in a through-manner. The guide can then be formed in an advantageous manner as an extrusion.

It may also prove advantageous if the guide device comprises a plurality of channels which are separated from one another in a pressure-tight manner, wherein the guide device is also preferably designed in this case as a single piece, i.e. without the assembly of a plurality of separate channel-forming devices. The plurality of channels may comprise a rinsing channel capable of guiding rinsing medium in a direction towards the wound end of the connection device and a negative pressure guiding channel for supplying negative pressure or conducting wound exudate. Any blockage problems inside the guide means can thus also be solved. Each channel communicates here with at least one opening in the guide.

The preferably flat guide means preferably extends over a known distance in the longitudinal direction and can then be converted by means of a transition element or coupling element, not shown, which can form a plug connection or an adhesive connection, into a conventional torsion-resistant circular hose which leads to a device for generating a negative pressure, which can be designed as a stationary device or as a mobile device which can be worn on the body of the patient. The transition or coupling element can also be designed for coupling a multichannel guide device to a multichannel circular hose. It has proven convenient for the length dimension of the guide means to have a range of 10-60 cm.

The planar carrier device of the connecting device, to which the preferably flat guide device is connected in a vacuum-tight manner at the manufacturer, is preferably likewise made of a flexible elastomer material with a shore a hardness of 5 to 60, in particular 10 to 60, in particular 15 to 50, in particular 15 to 40, and also in particular 15 to 35. The planar carrier device advantageously has a thickness of 0.75 to 3mm, in particular 1 to 3 mm. According to a preferred embodiment of the invention, the carrier device is designed silicon-based. According to another preferred embodiment, the guide means and the carrier means are formed from the same elastomeric material. The carrier device serves to hold and simultaneously support the flat guide device in a longitudinal section which communicates with the wound space. The dimensions of its planar form are therefore greater than the dimensions of the planar form of the guide in the longitudinal section of the wound side concerned. It has also proven to be advantageous if the planar dimensions of the carrier device are at least 1.5 times, preferably at least twice, the projected area of the guide device perpendicular to the carrier device, since the forces introduced during the contact by the guide device are thereby distributed over a larger area and no or little bending moments acting on the guide device are transmitted to the pressure bandage; these forces are better received by the plate-shaped carrier device. It has proven sufficient that the above-mentioned area ratios are up to 5, in particular up to 4, a ratio of 2 to 3 having proven advantageous.

The flat guide device may have a rectangular shape, for example, when viewed in cross section, wherein the two narrow sides are likewise and preferably rounded. According to a further embodiment of the invention, the guide device is designed as a trapezoid when viewed in cross section. The narrow sides then slope downward at an angle of inclination of, for example, 25 to 60 degrees, in particular 35 to 50 degrees, relative to the plane of the planar support device, wherein the waist of one or preferably both sides of the trapezoid does not have to be a straight line but can also run in a rounded manner.

The flat guide device is functionally connected to the vacuum-tight connection of the upper side of the carrier device facing away from the wound. For this purpose, an adhesive connection is basically considered in the broadest sense in the case of the use of adhesives. It has also proven advantageous to have a thermal bonding connection (fugeverbindung), which may correspond to a cured connection. For example, the guide device, which was produced separately in the past, can be applied to the planar carrier device which has just been cast and is only partially solidified, so that a material-fitting internal connection of the two components is then achieved without the use of additional adhesive.

It has proven to be advantageous if the openings in the guide device and in the carrier device, which openings communicate with one another, overlap one another, i.e. are flush with one another. It has proven to be possible in the simplest case to form these openings simultaneously in the two components only after the negative-pressure-tight connection of the flat guide device to the planar carrier device. This can be achieved, for example, by a stamping process that shapes the material.

In terms of the number and size of the openings in the guide device and the planar carrier material, it is conceivable to provide only a single opening. However, it has proven to be advantageous if, in the area of the connecting region of the guide device and the carrier device, which is sealed under vacuum, a plurality of openings, in particular at least two, in particular at least four, openings, are provided per cm of length of the guide device.

It has also proven advantageous if the clear opening area of the openings is 5 to 50% of the area of the surface sides of the guide means and the carrier means which are not releasably connected to one another.

All the features described above should be considered individually and in each case in any combination with the other features which are essential to the invention. Further features, details and advantages of the invention emerge from the appended claims, the drawing and the following description of a preferred embodiment of the invention.

Drawings

In the drawings:

fig. 1 shows a perspective view, not drawn to scale, of a connection device according to the invention and a wound shown with a negative pressure wound bandage, the device being used for negative pressure treatment of wounds; and

fig. 2 shows a schematic cross-sectional view, not drawn to scale, of the connecting device according to fig. 1.

Detailed Description

These figures show different views of the connection device of the invention, generally designated by reference numeral 2, for the negative pressure treatment of wounds. The connection device 2 shown is applied to the wound-facing upper side 4 of a schematic negative pressure bandage 6 which is applied to the wound 8 to be treated and is closed in a negative pressure-tight manner to the atmosphere and is adhesively secured thereto in a manner yet to be described.

The connecting device 2 comprises an exemplary illustrated flat guide device 10 made of an elastomer flexible material and a planar, extending, plate-like carrier device 12, which holds and supports the flat guide device 10 in such a way that the pressure or bending forces exerted on the guide device 10 can be introduced uniformly into and received by the planar carrier device 12.

The guide device 10 is designed to be flat, so that it is connected to the carrier device 12 in a longitudinal section 14 with almost 100% of its projected area onto the carrier material 12. The guide device 10 can be glued or cured (i.e. thermally bonded) by its plane side 15 concerned onto the upper side 16 of the carrier device 12 facing away from the wound.

Preferably, after the guide means 10 has been brought into negative pressure-tight engagement with the carrier means 12, openings 18 are formed through the carrier means 12 and through the guide means 10, which openings communicate with a schematically shown opening 20 or openings 20 in the negative pressure bandage 6 when the connecting device 2 is applied to the negative pressure bandage 6, in order to apply a negative pressure to the wound space.

The thickness dimension D of the composite consisting of the guide means 10 and the carrier means 12 is at most 7mm, preferably at most 5mm, and further preferably only 3-4 mm.

It can also be seen from the figures that the connection device 2 has an adhesive layer 24 on the wound-facing side 22 of the carrier device 12. By means of this adhesive layer 24, the connection device 2 can be arranged adhesively bonded towards the wound-facing upper side 4 of the negative pressure bandage 6. The adhesive layer 24 is designed as three sub-layers and comprises a central carrier sub-layer 26, a first adhesive sub-layer 28 held at the carrier sub-layer 26 and facing the carrier device 12, and a second adhesive sub-layer 30 held at the carrier sub-layer 26 and facing away from the carrier device 12 (that is to say facing the negative pressure bandage 6). In the exemplary and effectively illustrated case, all three layers of the adhesive layer 24 are designed to coincide with one another. Adhesive layer24 are cut or punched out as a whole from a flat material coated on both sides with a binder material. In the exemplary illustrated case, they are frame-shaped, i.e. are formed continuously in the circumferential direction and extend around the following central region 32 of the carrier device 12: in this central region, a schematically illustrated opening 18 of the carrier device 12 or of the guide device 10 is present in the direction of the negative pressure bandage 6. In the exemplary illustrated case, the tacky area of the first and second adhesive sub-layers 28, 30 is only about 30cm². However, it should also be clearly mentioned at this point that the adhesive layer 24 may also extend over the entire wound-facing side 22 of the carrier device 12, wherein it must in this way have through-openings which are flush with or communicate with the openings 18 in the carrier device or guide device. The viscous area is then still only about 40cm²。

The adhesive part-layers 28 and 30 consist of different adhesive materials, which are optimized for the material of the carrier device 12 or the negative pressure bandage 6. For example, if the carrier device 12 is made of silicon, it is proposed that the first adhesive sub-layer 28 comprises a silicon adhesive. When the negative pressure bandage 6, for which the connection device 2 is intended, is formed of polyurethane or has an upper side 4 facing away from the wound, which is formed of polyurethane, then it is proposed that the second adhesive layer 30 comprises an acrylate adhesive which has particularly good adhesion to polyurethane. By using the adhesive layer 24 according to the invention, it is possible in each case to match the two adhesive part-layers 28 and 30 thereof optimally to the material of the carrier device 12 or the negative pressure bandage 6 with which they interact adhesively and to form their components at the manufacturer.

In addition, the second adhesive sub-layer 30 is covered by a two-part releasable protective sub-layer 34 having a gripping tab 36 for disengaging the two parts.

Claims (16)

1. A connection device (2) for the negative pressure therapy of wounds, having a guide apparatus (10) that can be acted upon by negative pressure and having a planar, negative pressure-tight carrier apparatus (12) for the guide apparatus (10), at which carrier apparatus the guide apparatus (10) is held in a negative pressure-tight manner, wherein the carrier apparatus (12) can be placed on a negative pressure bandage (6) that covers the wound and is closed in a manner tight to the atmosphere, so that the guide apparatus (10) can be brought into communication with the wound space via at least one opening (18, 20) through the guide apparatus (10) and the carrier apparatus (12) and the negative pressure bandage (6), characterized in that an adhesive layer (24) having at least three part layers is provided on the wound-facing side (22) of the carrier apparatus (12), the adhesive layer comprises an intermediate carrier sub-layer (26), a first adhesive sub-layer (28) held at the carrier sub-layer (26) and facing towards the carrier device (12), and a second adhesive sub-layer (30) held at the carrier sub-layer (26) and facing away from the carrier device (12), and is designed such that it does not block the at least one opening (18) in the carrier device (12).

2. Connecting device according to claim 1, characterized in that the first adhesive part-layer (28) and the second adhesive part-layer (30) consist of adhesive materials with different adhesive properties.

3. Connecting device according to claim 1 or 2, characterized in that the carrier means (12) consists of silicon and the first adhesive sub-layer (28) comprises a silicon adhesive.

4. Connecting device according to claim 1, 2 or 3, characterized in that the second adhesive sub-layer (30) comprises an acrylate adhesive.

5. The connecting device according to one or more of the preceding claims, characterized in that the adhesive area of the first adhesive sub-layer (28) facing the carrier device (12) and/or the adhesive area of the second adhesive layer (30) facing the negative pressure bandage (6) is less than 45cm²Especially less than 40cm²Especially less than 35cm²Especially less than 30cm²。

6. The connecting device according to one or more of the preceding claims, characterized in that the connecting device (2) bonded to a smooth steel plate by means of its second adhesive sublayer (30) can withstand without damage a tensile force of at least 40N, in particular at least 50N, in particular at least 60N, in particular at least 70N, in particular at least 80N, in particular at least 90N, at a tensile angle of 0 degrees relative to the steel plate.

7. Connecting device according to one or more of the preceding claims, characterized in that an adhesive layer (24) is used, the first adhesive sub-layer (28) of which is designed such that the adhesive layer (24) has a peel force, relative to the steel plate, of 25 to 40N/100mm, in particular 27-35N/100 mm, imparted by this first adhesive sub-layer, and/or the second adhesive sub-layer (30) of which is designed such that the adhesive layer (24) has a peel force, relative to the steel plate, of 70 to 85N/100mm, in particular 70-80N/100 mm, adhered by this second adhesive sub-layer

8. The connecting device according to one or more of the preceding claims, characterized in that the first and second adhesive sub-layers (28, 30) have the same planar dimensions in projection onto their plane of extension, and in particular have the same dimensions as the carrier sub-layer (26).

9. The connecting device according to one or more of the preceding claims, characterized in that the first and second adhesive sub-layers (28, 30) have a thickness of 20-400 microns.

10. The connecting device according to one or more of the preceding claims, characterized in that the intermediate carrier sublayer (26) comprises or consists of: non-woven materials, planar materials with a textile bonding effect, such as, for example, knits, hook fabrics or wovens, or plastic foils, metal foils, or composites thereof.

11. The connecting device according to one or more of the preceding claims, characterized in that the adhesive layer (24) extends over the entire wound-facing side (22) of the carrier device (12).

12. Connecting device according to one or more of claims 1 to 10, characterised in that the adhesive layer (24) extends frame-like around the at least one opening (18) in the carrier device (12).

13. The connecting device according to one or more of the preceding claims, characterized in that the planar-like dimension of the adhesive layer (24) is at least 50% of the area of the wound-facing side (22) of the carrier device (12).

14. The connecting device according to one or more of the preceding claims, characterized in that the second adhesive sublayer (30) is covered by a releasable protective sublayer (34), which is preferably formed in two parts and preferably has a gripping tab (36) and/or an area which straddles the second adhesive sublayer (30) and can be gripped.

15. The connecting device according to one or more of the preceding claims, characterized in that the guide means (10) is designed to be flexible and flat and is fixed with a planar side (15) towards an upper side (16) of the carrier means (12) facing away from the wound.

16. The connecting device according to claim 15, characterized in that the guide means consists of a bendable elastomer material, preferably with a shore a hardness of at most 60, and that the guide means (10) is connected in a wound-side longitudinal section with at least 70% of its projected area perpendicular to the carrier means (12) in a non-releasable and planar manner with the carrier means (12) in the intended use, and that the composite made of guide means (10) and carrier means (12) has a thickness dimension of at most 7 mm.