CA3206750A1 - An aerosol-generating device comprising a micro electro-mechanical system - Google Patents

Abstract

The invention relates to an aerosol-generating device comprising a vapor generation unit (5) adapted to transform an aerosol forming material into vapor, and a vapor channel (4) extending from the vapor generation unit to a vapor outlet of the aerosol-generating device. The vapor generation unit (5) comprises a micro electro-mechanical system (MEMS). The vapor channel (4) is provided with a movable cover (10) having a closed position in which it closes the vapor channel (4) and an open position. The cover is adapted to move from the closed position to the open position under the effect of a suction applied on the aerosol-generating device by the user to vape. The cover (10) has a lower face provided with a layer of an absorbent material adapted to imbibe the aerosol forming material. This protects the vaporisation device from any foreign particles and avoids liquid leakage.

Description

2 An aerosol-generating device comprising a micro electro-mechanical system Field of the invention The present invention relates to an aerosol-generating device.
Aerosol-generating devices allow aerosolization of an aerosol forming material. The aerosol-generating devices according to the invention are also commonly called electronic cigarettes.
Aerosolization is the conversion of a substance, for example in liquid state or solid state, into particles small and light enough to be carried on the air.
Background of the invention An aerosol-generating device generally comprises a battery-powered vaporizer (or vaporisation device) which produces the vapor that is inhaled.
The usual configuration of the vaporizer used to vaporize a vaporizable material comprises a resistive heating element able to heat a wick imbibed with vaporizable material in liquid form.
Alternative vapor generation units are known, that use a microfluidic device. Such microfluidic vapor generation unit corresponds to a so-called "micro electro-mechanical system", also designated by the acronym "MEMS".
For example, W016064684 and DE102017123869 disclose microfluidic vapor generation unit which can be used for electronic cigarettes.

Those microfluidic vapor generation unit comprises a structure called MEMS die that comprises a plurality of small chambers. The vapor or aerosol is formed in the structure or at the outlet of this structure, for example by heating.
Micro electro-mechanical systems can also be used to induce high frequency vibrations in a small quantity of vaporizable material. These vibrations cause or promote the vaporization of the material.
Advantages of aerosol-generating devices using a microfluidic vapor generation unit or more generally a micro electro-mechanical system include small size, compact structure, lower power consumption, lower cost, increased reliability and higher precision, and high heat transfer efficiency.
However, aerosol-generating devices using MEMS as vapor generation unit may be subject to fluid leakage. More particularly, the vaporizable material in a liquid form that reaches the vapor generation unit but is not vaporized can leak from the aerosol-generating device if said device is shaken or unfavourably oriented (e.g.
with the outlet down). Generally, an aerosol-generating device using a MEMS as vapor generation unit is more likely to leak, through the capillary holes of the structure comprising such capillary holes, than usual vaporizers using a heating coil and an imbibed wick. Even if such leakage is usually a leakage of a small amount of product, it should be avoided.
Furthermore, the micro electro-mechanical systems must remain clean and clear of debris and dust to stay in good working conditions and to vaporize the vaporizable material effectively. The aerosol-generating devices are generally carried by their user in their pockets, and used in various environments and conditions. Consequently, introduction of foreign particles into the vapor channel of the device is likely to occur. These particles will reach the vapor generation unit and can soil and/or damage it. For example, they can plug the capillary structure of the vapor generation unit. While a cap can be provided to cover the mouthpiece of the aerosol-generating device and thus close the vapor channel to protect the vapor

3 generation unit from foreign particles, such cap can be lost and is not fully convenient for the user of the aerosol-generating device.
The present invention thus aims to provide an aerosol-generating device comprising a vapor generation unit comprising a MEMS, which addresses one or several of the above-mentioned problems.
Summary of the invention The present invention thus relates to an aerosol-generating device comprising a vapor generation unit adapted to transform an aerosol forming material into vapor, and a vapor channel extending from the vapor generation unit to a vapor outlet of the aerosol-generating device. The vapor generation unit comprises a micro electro-mechanical system (MEMS). The vapor channel is provided with a movable cover having a closed position in which it closes the vapor channel and an open position allowing vapor to pass. The cover has a lower face and is adapted to move from the closed position to the open position under the effect of suction applied on the aerosol-generating device by the user to vape. The lower face of the cover is provided with a layer of an absorbent material adapted to imbibe the aerosol forming material.
The absorbent material can be for example one of a fabric, sponge or foam. The absorbent material can imbibe the small quantity of liquid that can leak from the vapor generation unit. It helps in preventing the device from leaking.
The movable cover protects the vapor generation unit from any foreign matter that could damage or obstruct it. It also avoids leakage of liquid from the vapor generation unit. As the movable cover is opened by a suction applied on the aerosol-generating device, use of a separate cap to close the vapor channel when the device is not used is not necessary in some embodiments of the invention.
The lower face of the cover can be in close proximity to the vapor generation unit when the cover is in closed position. The vapor generation unit can

4 have an upper surface that is substantially flat, the lower face of the cover being in contact with the upper surface of the vapor generation unit when the cover is in closed position.
This enhances the protection against leaks provided by the movable cover.
The micro electro-mechanical system advantageously comprises a MEMS die. In such embodiment, the upper surface of the vapor generation unit is generally the upper surface of its MEMS die and said upper surface is provided with small chambers.
As vapor generation units based on micro electromechanical systems are more subject to malfunction due to obstruction than conventional heaters, the present invention is of particular interest in aerosol-generating devices using such vapor generation units.
The aerosol-generating device can comprise a spring which tends to return the cover to the closed position. The cover can comprise a hinged flap.

According to another embodiment, the cover is constituted by an elastically deformable piece.
Various embodiments of covers can thus be used in the invention, depending on many parameters such as the device configuration, the expected reliability of the cover, its cost, etc.
The vapor generation unit can comprise one or several MEMS dies provided on a printed card circuit. For example, the vapor generation unit can comprise two MEMS dies.
Use of a plurality of micro electro-mechanical systems can help to produce a sufficient quantity of vapor and/or can provide a large vapor production surface to obtain a homogeneous aerosol.
The aerosol-generating device can comprise a main body and a cartridge.
The main body can comprise the vapor generation unit and the cartridge can comprise a reservoir of vaporizable material, and the cover is comprised in the main body.
According to another embodiment, the main body can comprise the vapor generation unit and the cartridge can comprise a reservoir of vaporizable material,

5 and the cover is comprised in the cartridge.
Depending on the embodiment of the invention, the cover will thus be used during the whole lifetime of the device or be replaced each time the cartridge is replaced.
Brief description of the drawings Other particularities and advantages of the invention will also emerge from the following description.
In the accompanying drawings, given by way of non-limiting examples:
- Figure 1 represents, in a partial schematic sectional view, an aerosol-generating device according to an example embodiment of the invention, a movable cover of the device being in a closed position;
- Figure 2 represents the an aerosol-generating device of Figure 1, the cover being in an open position;
- Figure 3 represents, in a schematic sectional view, an example embodiment of a movable cover that can be used in the invention;
- Figure 4 represents, in a schematic three-dimensional view, an aerosol-generating device according to a second example embodiment of the invention;
- Figure 5 represents, in a schematic three-dimensional view, an example embodiment of a vapor generation unit that can be used in the invention;
and - Figure 6 represents, in a schematic sectional view, an example embodiment of a vapor generation unit that can be used in the invention.

6 Detailed Description Figure 1 and Figure 2 represent an aerosol-generating device according to an example embodiment of the invention.
The aerosol-generating device comprises a reservoir 1. The reservoir 1 defines an inner volume 2 that is adapted to contain an aerosol forming material.
The term aerosol forming material is used to designate any material that is aerosolizable in air to form an aerosol. The vaporizable material may, for example, be in liquid form, in solid form, or in a semi liquid form, thus comprise or consist of an aerosol-generating liquid, gel, paste or wax or the like, or any combination of these.
In the present invention, the aerosolization doesn't involve a phase change from the aerosol forming material to gas. It generally creates an aerosol using thermal firing chambers. The working principle is similar for example to that of the thermal inkjet functioning. The aerosol forming material droplets are ejected from at least one MEMS die by applying a pulse of pressure to the material supplied in the chambers of the MEMS die.
To create this pressure pulse "thermal ink jet" principle can be applied as follows:
MEMS dies have a series of small chambers, each containing a heater therein;
- water in the material is heated by the heater until it is vaporized (because boiling point of water is reached) and bubble is created. The propylene glycol (PG) and the vegetable glycerine or glycerol (VG) present in the aerosol forming material will not vaporize as boiling points of those components are higher than the boiling point of water at the same atmospheric pressure); and - rapid expansion of the bubbles causes the formation of the PG/VG
droplets, which are ejected out of the MEMS dies.
More particularly, the aerosol forming material is heated by the heater of the

7 at least one MEMS die until it starts to boil and a gas bubble is created. The gas bubble is comprised of a phase change of the aerosol forming material, usually liquid, and potentially air trapped in the liquid. The amount of the aerosol forming material being boiled is about 1% of the total amount. In other words, around 1% of the aerosol forming material is superheated to form a gas bubble. This 1%
consists of the amount of aerosol forming material that is the closest to the heater.
Gas being much more voluminous than liquid, it provides the force to push out from the vapour generation unit. This allows approximately 80-90% of the aerosol forming material above the gas bubble to be ejected.
Gas bubbles grow as they are heated until being large enough that they force liquid droplets to be ejected. The gas bubbles also escape when the liquid droplets are ejected. This creates a vacuum which causes more liquid to be drawn into the vapor generation unit 20 from the reservoir 33. The process then repeats.
It shall be noted that the propylene glycol (PG) and the vegetable glycerine (VG) that may be present in the aerosol forming material may not vaporize as boiling points of these components are higher than the boiling point of water at the same atmospheric pressure. However, because the high temperature's heater, it is very possible that all of the aerosol forming material near the heater, regardless of composition, is superheated and undergoes the phase change to the gas bubble.
In other words, the 1% amount of the aerosol forming material that is superheated can be made up of a mixture of components that is similar to that of the rest of the aerosol forming material.
The reservoir can be, by way of example, a one-piece plastic part, for example obtained by injection moulding.
In the represented first example embodiment of Figure 1, the reservoir 1 is provided in an upper part of the aerosol-generating device, towards a mouthpiece 3 of the aerosol-generating device. The reservoir 1 thus can comprise or can form, at its upper end, a mouthpiece 3. The mouthpiece 3 comprises a vapor outlet and is the part of the aerosol-generating device where the user places his mouth to vape,

8 i.e. to inhale the aerosolized material. A vapor channel 4 connects the mouthpiece 3 to a vapor generation unit 5 where the aerosol forming material is aerosolized. In the represented embodiment, the vapor channel 4 is a central tube that is mainly formed by the reservoir 1.
The aerosol-generating device comprises MEMS (micro-electro mechanical systems) advantageously comprising one or several microfluidic structures named MEMS die. More particularly, the MEMS die of the present embodiment as explained above is a microfluidic structure comprising a series of small chambers. Each small chamber contains a heater therein (not shown), which heats the water contained in the aerosol forming material until only the water vaporizes as the boiling point of the water is lower than the boiling points of PG (propylene glycol) and VG
(vegetal glycerin) components contained in the aerosol forming material. Rapid expansion of the bubbles causes the formation of the PGNG droplets, which are ejected out of the MEMS die.
The vapor generation unit 5 is provided with liquid from the reservoir by a liquid path 6. The liquid path comprises a liquid channel 7 that fluidically connects the reservoir 1 (and more particularly the inner volume 3 of the reservoir 1) and a filter chamber 8. The filter chamber 8 comprises a filter 9, for example a mesh such as a metallic mesh, preferably a stainless-steel mesh. The liquid coming from the reservoir must cross the filter 9 to reach the vapor generation unit. The filter 9 prevents the passage of particles from the reservoir to the vapor generation unit.
Such particles, which could be introduced into the reservoir 1 during its filling and / or which could come from a poor quality aerosol forming material, could interfere with the operation of the vapor generation unit. In particular, they could plug the small chambers of the microfluidic structure of the MEMS die.
The capillary displacement of the aerosol forming material is effected on the material in a liquid state. If not already provided by the reservoir as a liquid, the transformation of the aerosol forming material into a liquid state can be obtained by heating. This may for example be the case if the reservoir 1 contains a vaporizable

9 material consisting of or comprising a wax.
In the represented embodiment of Figures 1 and 2, the aerosol-generating device comprises several liquid channels 7, namely two liquid channels 7.
According to alternative embodiments of the invention, the reservoir 1 can comprise a single inner volume 3 or several independent inner volumes 3. Each inner volume of the reservoir is connected to the filter chamber 8 by one liquid channel 7 or several liquid channels 7.
The aerosol-generating device further comprises a movable cover 10.
The cover 10 is configured to move between a closed position in which it closes the outlet channel and an open position in which the outlet channel is free, and vice-versa. The cover is represented in its closed position in Figure 1 and in its open position in Figure 2.
The cover 10 is adapted to move from the closed position to the open position under the effect of suction applied on the aerosol-generating device (i.e. on the mouthpiece 3) by the user to vape.
Figure 3 represents in detail an example embodiment of a movable cover 10 that can be used in the invention. In Figure 3, the cover 10 is in its closed position.
The cover 10 comprises a closing plate 11. The closing plate 11 has a shape that corresponds (with a functional clearance) to the cross section of the vapor channel 4.
When the cover 10 is in closed position, the closing plate 11 extends across the vapor channel 4. The closing plate 11 thus closes the vapor channel 4. In the closed position, the closing plate 11 can bear on a seat 12 provided on the wall of the vapor channel 4. The cover 10 comprises a hinge 13. The closing plate 11 is thus articulated with respect to the rest of the aerosol-generating device. The movable cover moves to the open position by rotation of the closing plate 11 around the hinge 13. In this embodiment, the closing plate is thus a flap. The hinge can be formed, by way of example, by a small pivot shaft, or by a part deformable along the hinge axis.
A spring 17, for example a torsion spring or any other adapted elastic element, tends to return the cover to its closed position. The return force of the spring must however be low enough so that the force caused on the cover by suction of the user on the mouthpiece 3 is sufficient to open the cover 10.
In Figure 2, in which the movable cover 10 is in open position, the closing plate 11 is schematically represented in a fully pivoted position, i.e.
extending 5 orthogonally compared to its position when the movable cover 10 is in closed position. Of course, depending on the configuration of the cover 10 and on the cross section of the vapor channel 4, the closing plate 11 can be significantly less pivoted in the open position than shown in Figure 2, as long as the passage of vapor is possible through the movable cover.

10 The vapor flow is represented by arrows in Figure 2.
The cover 10 has a lower face 14 and an upper face 15. The lower face 14 of the cover 10 is oriented towards the vapor generation unit 5, i.e. it faces the vapor generation unit 5 when the cover 10 is in closed position. In the represented embodiment, the lower face of the cover 10 corresponds to the lower face of the closing plate 11.
The lower face 14 of the cover 10 is advantageously provided with a layer of an absorbent material 16. The absorbent material 16 is adapted to imbibe liquid, in particular a liquid aerosol forming material issued from the reservoir 1.
The absorbent material 16 is thus adapted to retain liquid that would leak from the vapor generation unit 5. Many absorbent materials can be used. Foam, e.g. plastic foam can be used. The absorbent material can also comprise fabric (e.g. felt), or sponge.
When the cover 10 is in closed position, its lower face 14, provided with absorbent material 16, is in close proximity to the vapor generation unit 5.
By close proximity, is meant a very short distance (e.g. less than 2mm or less than lmm) or in contact.
Thus, the lower face 14 of the cover 10 is advantageously in contact with an upper surface of the vapor generation unit 5.
More particularly, when the vapor generation unit comprises a microfluidic structure (MEMS die) comprising small chambers, the upper surface of the vapor

11 generation unit is generally also the upper surface of the MEMS die.
If the cover 10 is in contact with the upper surface of the microfluidic structure when in closed position, it closes the outlets of the small chambers of the microfluidic structure. The absorbent material can directly imbibe any liquid that would exit from the small chambers.
As the element causing the aerosolization of the liquid is located under the surface of the microfluidic structure, the cover 10, even if it is in contact with the vapor generation unit when it is closed, is not in contact with the element which causes the aerosolization.
Thus, providing a layer of absorbent material 16 on the lower face 14 of the closing plate 11 (or, more generally, of the cover 10) is not a problem with this type of vapor generation unit (whereas with a conventional vapor generation unit comprising a wick, the contact of the absorbent material with the wick would cause the absorbent material to drain liquid from the reservoir).
The movable cover 10 can have various configurations, according to alternative embodiments of the invention.
The movable cover can for example comprise a plurality of hinged plates or flaps. The cover can be constituted by an elastically deformable part. This elastically deformable part can for example be a deformable foil comprising one or more slits which open when a pressure difference exists between the faces of the foil.
The elastically deformable part can be made of silicone, other rubbery material, plastics, or metal.
Figure 4 represents an aerosol-generating device according to a second example embodiment of the invention. In this embodiment, the aerosol-generating device has an elongated shape. The mouthpiece 3 is located at one extremity of the aerosol-generating device. The reservoir 1 is located under the vapor generation unit 5 and forms two separate inner volumes 2. The reservoir 1 is formed, in the represented embodiment, of two distinct hollow tubes.
A battery 18 provides the vapor generation unit 5 and the other electrical

12 components of the system with electricity. The battery 18 is attached to a main printed circuit board 19 (PCB) of the aerosol-generating device. The main printed circuit board constitutes the main support structure for the various elements of the aerosol-generating device.
Figure 5 represents an example vapor generation unit that is particularly adapted to be used in the example embodiment of Figure 4. The vapor generation unit 5 of Figure 5 comprises two MEMS dies 20. The two MEMS dies 20 are fastened, e.g. soldered, to a printed circuit board 21. Each MEMS die 20 has an upper surface 22 formed by a microfluidic structure. The two upper surfaces are aligned, at a same level, and thus form the upper surface of the vapor generation unit 5.
On the opposite side of the printed circuit board 21, the vapor generation unit 5 comprise two inlet ports 23. Each inlet port 23 is configured to be fluidically connected to an inner volume of the reservoir of the aerosol-generating device.
The device of Figure 4 is covered with a casing (omitted in Figure 4 to show the inner parts of the aerosol-generating device).
Figure 6 represents in a cross-sectional diagram a portion of an example of an aerosol-generation device comprising in a different configuration a vapor generation unit 5. The vapor generation unit 5 of figure 6 is similar to that of figure 5 and is also particularly adapted to be used in embodiments of the present invention.
The vapor generation unit 5 also comprises here two microfluidic structures or MEMS dies 20. Each MEMS die 20 of the vapor generation unit 5 has an upper surface or vaporization surface 22.
The vapor generation unit 5 is in fluid communication with two fluidic connections or liquid channels 7 each of which is arranged to transport the liquid aerosol forming material from the reservoir 1 to the vapor generation unit 5.
Each liquid channel 7 is connected to a MEMS die 20 through an inlet port 23.
Liquid aerosol forming material is drawn from each liquid channel 7 to a MEMS die 20 e.g.
by capillary force.

13 Two aerosol flow paths 24 are arranged here to fluidly communicate with the mouthpiece of the aerosol-generating device. Each aerosol flow path 24 allows thus the generated aerosol to flow from a MEMS die 20 of the vapor generation unit 5 to the mouthpiece. In other words, airflow paths connect air inlets (not shown) within the aerosol-generating device to the mouthpiece for the passage of air through the aerosol-generating device.
A downstream end of each aerosol flow path 24 forms a nozzle 25. The nozzles 25 and the vaporization surfaces 22 are usually on parallel planes. In other words, each nozzle 25 face a vaporization surface 22.
Each nozzle 25 can be offset from the vaporization surface 22 or alternatively, the nozzle 25 and the vaporization surface 22 may align direction one above the other.
When a user draws on the mouthpiece of the device, air is brought into the aerosol flow paths 24 through the air inlets connected to the aerosol flow paths 24 so as to create a pressure change that draws the generated aerosol flow to the mouthpiece as it passes over the vaporization surface 22.
In a setup where each nozzle 25 is offset from a corresponding vaporization surface 22, incoming air through the air inlets can flow sideways along the vaporization surface 22 and then pulls up from the nozzle 25. Alternatively incoming air through the air inlets can flow directly into the aerosol flow path over the vaporization surface 22. The nozzle 25 is jetting either perpendicular to, or in parallel with the airflow of the mouthpiece.
While the aerosol-generating device of Figure 4 cannot be disassembled, the aerosol-generating device of Figures 1 and 2 can be composed of a main body and a removable cartridge.
The main body comprises the vapor generation unit 5. The main body, which is only partially represented in Figures 1 and 2, also comprises the battery and main electronic components (microprocessor, sensor(s), etc.) of the aerosol-generating device.

14 The cartridge comprises the reservoir 1, and thus the aerosol forming material.
According to alternative embodiments of the invention, the cover 10 is comprised in the main body, or in the cartridge.
The cartridge can be a consumable item. Once the aerosol-forming material initially contained in the reservoir has been consumed, and the reservoir is empty, the cartridge is replaced by another cartridge with a full reservoir. The old cartridge can be discarded, preferably for recycling. A change of cartridge can also be carried out, even before it is empty, in order to change the product to be vaped. This allows for example the user to choose the taste of the product that he consumes.
The aerosol-generating device developed in the invention thus comprises a combination of a vapor generation unit that uses a micro electro-mechanical system and of a movable cover that opens under the effect of a suction applied on the aerosol-generating device and that has a lower face provided with a layer of an absorbent material.
This provides advantages in terms of vapor quality and homogeneity, energy efficiency, and compactness, without the main drawbacks of this technology.
More particularly, the movable cover protects the vapor generation unit from foreign particles, and avoids leakage of liquid from the vapor generation unit.
Furthermore, the absorbent material prevents the device from leaking by imbibing liquid that would exit from the vapor generation unit.
References used for the fioures 1 Reservoir 2 Inner volume 3 Mouthpiece 4 Vapor channel 5 Vapor generation unit 6 Liquid path 7 Liquid channel 8 Filter chamber 9 Filter 10 Cover 11 Closing plate 12 Seat 13 Hinge 14 Lower face (of the cover)

15 Upper face (of the cover)

16 Absorbent material

17 Spring

18 Battery

19 Main printed circuit board MEMS die 21 Printed circuit board 22 Upper surface (of a MEMS die) 23 Inlet port 24 Aerosol flow paths Nozzle

Claims (13)

16

1. An aerosol-generating device comprising a vapor generation unit (5) adapted to transform an aerosol forming material into vapor, and a vapor channel (4) extending from the vapor generation unit to a vapor outlet of the aerosol-generating device, the vapor generation unit (5) comprising a micro electro-mechanical system (MEMS), the vapor channel being provided with a movable cover (10) having a closed position in which it closes tho vapor channel (4) and an open position allowing vapor to pass, the cover (10) having a lower face (14) and being adapted to move from the closed position to the open position under the effect of suction applied on the aerosol-generating device by the user to vape, wherein the lower face (14) of the cover is provided with a layer of an absorbent material (16) adapted to imbibe the aerosol forming material.

2. An aerosol-generating device according to claim 1, wherein the absorbent material (16) is one of a fabric, sponge or foam.

3. An aerosol-generating device according to claim 1 or 2, wherein the lower face (14) of the cover (10) is in close proximity to the vapor generation unit (5) when the cover is in closed position.

4. An aerosol-generating device according to claim 3, wherein the vapor generation unit has an upper surface that is substantially flat, the lower face of the cover being in contact with the upper surface of the vapor generation unit when the cover (10) is in closed position.

5. An aerosol-generating device according to any one of the preceding claims, wherein the micro electro-mechanical system comprises a MEMS die (20).

6. An aerosol-generating device according to claim 4 and claim 5, wherein the upper surface of the vapor generation unit (5) is the upper surface (22) of its MEMS die (20) and wherein said upper surface (22) is provided with small chambers.

7. An aerosol-generating device according to any one of the preceding claims, wherein it comprises a spring (17) which tends to return the cover (10) to the closed position.

8. An aerosol-generating device according to any one of the preceding claims, wherein the cover (10) comprises a hinged flap.

9. An aerosol-generating device according to any one of the preceding claims, wherein the cover is constituted by an elastically deformable piece.

10. An aerosol-generating device according to any one of the preceding claims, wherein the vapor generation unit comprises one or several MEMS dies provided on a printed card circuit.

11. An aerosol-generating device according to claim 10, wherein the vapor generation unit comprises two MEMS dies (20).

12. An aerosol-generating device according to any one of the preceding claims, comprising a main body and a cartridge, the main body comprising the vapor generation unit and the cartridge comprising a reservoir (1) of vaporizable material, wherein the cover is comprised in the main body.

13. An aerosol-generating device according to any one of claims 1 to 11, comprising a main body and a cartridge, the main body comprising the vapor generation unit (5) and the cartridge comprising a reservoir (1) of vaporizable material, wherein the cover (10) is comprised in the cartridge.