WO2011161246A2

WO2011161246A2 - Swellable substance actuator and delivery device, in particular for a medicinal active substance

Info

Publication number: WO2011161246A2
Application number: PCT/EP2011/060631
Authority: WO
Inventors: Michael Vosseler
Original assignee: Hsg-Imit - Institut Für Mikro- Und Informationstechnologie
Priority date: 2010-06-24
Filing date: 2011-06-24
Publication date: 2011-12-29
Also published as: DE102010030502A1; WO2011161246A3

Abstract

The invention relates to a device (1) for generating a volume work which can be driven by a swellable substance (9), preferably for a delivery device for delivering a medicinal active substance, with a swellable substance chamber (10) of variable volume which is filled with a swellable substance (9) and can be brought into a flow connection with a liquid reservoir (9) of variable volume. According to the invention, before initiation of the swelling operation the flow connection between the liquid reservoir (3) and swellable substance chamber (10) is interrupted by at least one barrier (6, 24) which opens when a predetermined opening pressure arises at the barrier (6, 24). It is furthermore intended that the wall of the liquid reservoir (3) is bag-like, and in particular is of a construction which is flexibly limp but has little extensibility.

Description

Swellable substance actuator and delivery device, in particular for a medicinal active substance

Description

Field of the invention

The invention relates to a device for generating a volume work which can be driven by a swellable substance, in particular for a delivery apparatus for delivering a medicinal active substance, with a swellable substance chamber of variable volume which is filled with a swellable substance and can be brought into a flow connection with a liquid reservoir of variable volume. The invention furthermore relates to a delivery apparatus equipped with this.

Background of the invention

A swellable substance actuator of the abovementioned type is known from the international patent application WO 2004/062714 A1 . The delivery apparatus comprises on the one hand an actuator chamber filled with a swellable substance and on the other hand a reservoir for the liquid swelling agent which has a dimensionally stable or elastic covering. If a dimensionally stable shell is used, a stopper running into this is charged with an increased pressure by a spring- actuated pretensioning apparatus, so that on the one hand a pressure sufficient to overcome the force of gravity is effected, and on the other hand the reducing volume of liquid due to exit of the swelling agent is compensated. On the other hand, if the reservoir is rubber-elastic in construction, the swelling agent can already be stored in this under an increased pressure and therefore with elastic widening of the covering. In this case the volume is compensated by a contraction of the covering, the energy stored in the rubber membrane being released. The actuator chamber and reservoir are separate from one another in the initial state, and can be brought into a flow connection by puncturing the elastic covering or opening a shut-off valve. The cross-section of the flow connection can be predetermined by porous inserts.

Under the action of the liquid swelling agent, the swellable substance in the actuator chamber, which is dimensionally flexible or of variable volume by means of a plunger, starts to swell and expands this. As a result, a long-lasting pressure is exerted on an active compound stored in the delivery apparatus, which is consequently released into the patient's body. One disadvantage of this delivery apparatus can be that it may be relatively expensive with respect to its

construction and its assembly.

The laid-open specification DE 41 06 624 A1 describes an osmotically driven infusion pump for slow and long-lasting release of solutions or dissolved medicaments, which is driven by salination forces. It has two chambers which are separated by a semipermeable membrane and in which fluids of different concentration are stored. The fluid of higher concentration is diluted by the fluid of lower concentration, as a result of which its volume increases. The pressure thereby generated drives a pump plunger, which in its turn forces into the patient's body the solution to be injected. A disadvantage of this infusion pump may be that some of the volume work must be used to overcome the forces of friction between the pump plunger and the barrel guiding it.

German Patent Application 10 2008 057 822.3 furthermore discloses a bag arrangement, which is in one piece but divided into two chambers, for providing active compounds, which are delivered to a dermal interface by means of an actuator acting on the bag arrangement from the outside. The first chamber forms a reservoir, in which a substance or a solvent is held in reserve. The second chamber is connected to the dermal interface. The separation between the chambers of the bag arrangement is at least partly removed under the action of the pressure generated by the actuator, so that the contents of the first chamber can arrive at the dermal interface through the second chamber. Object on which the invention is based

The invention is based on the object of providing a device for generating a volume work which can be driven by a swellable substance and is improved with respect to the prior art. The invention is furthermore based on the object of providing an improved delivery apparatus which has a device for generating a volume work which can be driven by a swellable substance.

Solution according to the invention

The object on which the invention is based is achieved according to the invention by a device for generating a volume work which can be driven by a swellable substance (also called "swellable substance actuator" in the following) which comprises a swellable substance chamber of variable volume which is filled with a swellable substance and can be brought into a flow connection with a liquid reservoir of variable volume which is not necessarily part of the device, the flow connection between the liquid reservoir and swellable substance chamber in the state of the device before initiation of the swelling operation being interrupted by at least one barrier which opens when a predetermined opening pressure arises at the barrier. The opening pressure can advantageously be generated by applying an external force to the liquid reservoir. Advantageously, due to the barrier according to the invention, particular tools, which are integrated into the device or are separate, for establishing the flow connection between the liquid reservoir and swellable substance chamber can be dispensed with, so that the expenditure on construction is relatively low and construction space for such means does not have to be provided. A reliable and simple activation of the swelling operation is possible by the invention. At the same time, an unintentional activation of the swelling operation can advantageously be almost ruled out. The forces required for opening the barrier are preferably adjusted such that the remaining structures forming the flow path are not destroyed.

The object is furthermore achieved by a device for generating a volume work which can be driven by a swellable substance, which comprises a swellable substance chamber of variable volume which is filled with a swellable substance and can be brought into a flow connection with a bag-like liquid reservoir, the wall of the bag-like liquid reservoir being of a construction which is flexibly limp but has tensile strength. The wall thus has precisely no rubber-elastic properties which impede driving out of the liquid by application of external pressure. It is also advantageously achievable that the wall itself exerts no pressure on the contents of the liquid reservoir, but the liquid reservoir can nevertheless fold up during its emptying, in order to compensate the volume shrinkage. The device according to the invention for generating a volume work which can be driven by a swellable substance can be particularly advantageously employed in a delivery apparatus for delivering a medicinal active substance, e.g. with the bag arrangement according to German Patent Application 10 2008 057 822.3. The object is accordingly also achieved by a delivery apparatus with a device according to the invention for generating a volume work which can be driven by a swellable substance.

A delivery apparatus constructed according to the invention can be particularly advantageously employed for intradermal infusion instead of a subcutaneous infusion or injection. Hypersensitivities mediated by immune complexes can be reduced in this use, especially if the active compounds are released close to the boundary between the dermis and subcutaneous fatty tissue, as is proposed, for example, in WO 2006/031856. With intradermal administration of vaccines, it is possible to considerably reduce, for example to one fifth, the amount of active compound to be administered without impairing the immunoprotection, see R. T. Kenny et al., "Dose sparing with intradermal injection of influenza vaccine", N. Engl. J. Med., 2004, 351 (22), 2295-2301 . Due to shorter diffusion paths and the rapid transfer of the active compound molecules into the blood vessels, an advantageous result can be that these are scarcely exposed to dermal

metabolism. With intradermal administration, protein and peptide active

compounds can advantageously be made available to the body more rapidly with the invention due to their sometimes very high molecular weight. The invention can also be employed in particular for the purpose of continuous infusion, preferably for continuous intradermal infusion. Since the intradermal medium has a very high immunocompetence for defence against pathogens, a lower rate of infection is to be expected with intradermal continuous infusion compared with subcutaneous continuous infusion.

However, applications of the delivery apparatus according to the invention outside of medicine are also conceivable, for example for the controlled release of evaporation liquids for cooling of components.

Preferred embodiments of the invention

Advantageous embodiments or further developments, which can be employed individually or in combination with one another, are the subject matter of the dependent claims.

In a preferred embodiment of the invention, the barrier or at least one of the barriers is constructed as a breakable seal. A breakable seal in the context of the present invention is a fluidic interruption of a flow path which is deliberately to be released, by means which are arranged within this and are not directly accessible from the outside, preferably by a separable contact with internal walls of the flow channel which closes the entire cross-section of the flow channel at one place in the flow path. In this context, the walls can be connected to one another by material locking, for example by gluing or welding (peel seam), or optionally also by positive locking, for example by clipping together catches. When a force which is generated by the opening pressure and spreads the walls apart exceeds the maximum load accommodated by the breakable seal, the material or positive lock is released. However, it is also conceivable that a non-permeable membrane of low strength which closes the flow channel locally and which tears and releases the flow path when a limiting pressure against the membrane is exceeded is incorporated. The release of the fluidic interruption will as a rule be permanent. In particular cases, in particular if a breakable seal acting as a positive lock is used, renewed, deliberate closing of the flow path, however, is not ruled out.

In a preferred embodiment of the invention, the barrier or at least one of the barriers is constructed as a pretensioned valve. A pretensioned valve in the context of the present invention is a valve with which, for it to be opened in the flow direction, a predetermined opening pressure from the arriving liquid is necessary. In a preferred embodiment of the invention, a check valve is present in the flow connection between the liquid reservoir and swellable substance chamber in order to avoid backwards flow of the liquid against the envisaged flow direction leading to the swellable substance chamber. Particularly preferably, the pretensioned valve is constructed as such a check valve.

In a preferred embodiment of the invention, an intermediate chamber is present upstream of the swellable substance chamber in the flow connection between the liquid reservoir and swellable substance chamber. The intermediate chamber can advantageously serve as a liquid intermediate store. Particularly advantageously, the intermediate chamber is arranged entirely or partly in a dimensionally stable container. By this means, advantageously, a change in volume by exertion of force from the outside can be prevented and the intermediate chamber can be protected from damage. Furthermore, in this way no force from the outside can influence the swelling process.

Preferably, the barrier which opens when a predetermined opening pressure is applied is arranged between the liquid reservoir and the intermediate chamber. The intermediate chamber can then advantageously form a capacity in the sense that it is capable of accommodating part of the amount of liquid which emerges spontaneously from the liquid reservoir after opening of the breakable seal. As a result, injection of an unintentionally and undesirably large amount of liquid into the swellable substance chamber can be prevented. Under certain circumstances, the chamber can be quite small. The amount of liquid emerging spontaneously from the liquid reservoir chiefly depends on the elasticity of the liquid reservoir and the mechanism with which the volume of the liquid reservoir is reduced. If the elasticity is low, the amount of liquid emerging spontaneously is therefore also small, If the breakable seal is opened by exerting pressure with the thumb and forefinger, the amount of liquid emerging spontaneously is very large. This is due to the fact that after the breakable seal has been opened, relevant counter-pressure is no longer available and the thumb and forefinger immediately start to empty the contents of the liquid reservoir. In this case a chamber with a relatively large volume is necessary. That is to say it is most appropriate if the user transfers the contents of the liquid reservoir completely from the liquid reservoir into the chamber.

If the chamber can accommodate the entire liquid for carrying out the swelling operation when the invention is used as intended, an advantageous result can be that the liquid reservoir has to be connected to the device only temporarily for feeding the liquid into the intermediate chamber, and can then be removed again. The liquid reservoir can be constructed e.g. as a syringe or the like, but a removable bag is also conceivable. The check valve in such as embodiment of the invention is preferably arranged such that after the liquid reservoir has been removed, flowing out of the liquid from the intermediate chamber against the envisaged flow direction can be prevented.

Also preferably, a means, which can be removed by the liquid emerging from the liquid reservoir, for delaying the swelling operation is provided in the flow path to the swellable substance chamber. As a result, the volume work performed by the device can be controlled with respect to time with simple construction measures which require little construction space. A time delay of several hours can be achieved with this measure. Particularly preferably, the means is arranged between the intermediate chamber and the swellable substance chamber or between the spacer discussed below and the swellable substance. Preferably, a flat spacer is present in the flow path between the liquid reservoir and swellable substance chamber, which on the one hand supports the

downstream structures and furthermore can distribute the liquid causing the swelling operation uniformly over a large surface area of the swellable substance or of a filter arranged between the spacer and swellable substance (see below), The spacer, in the form of a distance layer, can thus provide a flow path for a transverse flow directed orthogonally to the exit from the second intermediate chamber. The preferred spacer can be made of, for example, a (preferably wide- mesh) filter material. In principle, materials which have both a supporting and a liquid-transporting (e.g. by means of capillary forces) property can be employed.

In a preferred embodiment of the invention, the spacer has liquid-storing

properties. An advantageous result of this can be that the spacer can partly or completely take over the task of the intermediate chamber. It is important that the liquid is only so weakly bound in the spacer that the swellable substance can remove it from the spacer.

Suitable materials for the spacer are e.g. nonwovens or a sponge-like material. Particularly suitable liquid-storing materials are e.g. the "Porous plastic and oriented fibre products" from Porex Technologies GmbH, Aachen. These are porous, hydrophilic components of customized shape e.g. of polyethylene or polypropylene. It is also conceivable to combine materials which each in

themselves have only one or two of the properties of transporting, supporting and intermediate storing. A flat filter preferably arranged between the spacer and the swellable substance present in the swellable substance chamber can prevent swellable substance from leaving the swellable substance chamber through the flow path. It can also prevent the spacer from becoming blocked with swellable substance and becoming impermeable to flow. The filter can also be, in particular, a semipermeable membrane. Embodiments of the filter in which this comprises several layers of different material are also conceivable.

Embodiments of the invention in which the spacer itself at least partly assumes the function of the filter are of course also conceivable. For this, the spacer is preferably porous in construction. Particularly preferably, the function of the filter and of the spacer is combined in one component, so that the spacer completely assumes the function of the filter.

The wall of the liquid reservoir is preferably bag-like in construction and particularly preferably of a construction which is flexibly limp but at the same time has tensile strength. This means in particular that the wall has precisely no rubber-elastic properties (or at least none which impede driving out of the liquid by application of external pressure). Furthermore, preferably it does not itself exert any pressure on the contents of the liquid reservoir. Nevertheless, the liquid reservoir is capable of folding up during its emptying and therefore of compensating the volume shrinkage. The wall preferably has a tensile E modulus of at least 200 N/mm² (Newton per square millimetre) and is made inter alia, for example, from

polyolefinic plastics, in particular polyethylene (PE), polypropylene (PP) or copolymers thereof. The form of the liquid reservoir can be flat in construction, so that the construction height is correspondingly low. Particularly advantageously, the bag-like liquid reservoir is arranged entirely or partly in a dimensionally stable container and is therefore well -protected from damage. The container is preferably equipped with means for transferring pressure to the liquid reservoir, so that no direct manipulation of the liquid reservoir is necessary for initiation of the swelling operation. In this context, the means for transferring pressure can advantageously comprise a region of the container wall which is arranged displaceably, so that the swelling operation can be triggered by a simple pressure on the part of the container wall in question. It goes without saying that the container wall can be equipped with a releasable lock, which avoids unintentional actuation of the device. This advantage can be achieved by a particularly easy construction if the displaceable region of the container wall is connected rotatably to the remainder of the container. A lock can be effected in this case by a simple, removable blocking body which is arranged in the swivelling region of the container wall and, for example, is connected to this in one piece via an intended breaking point.

Advantageously, means are provided which limit the change in volume of the liquid reservoir which can be achieved by exertion of force from the outside. As a result, the amount of liquid which arrives at the swellable substance simultaneously with the opening of the barrier can be limited. The pressure which can be generated in the liquid reservoir can also thus be limited particularly favourably by this means. A means of particularly favourable construction can be that in which the

displacement of the container wall is limited by a stop, and consequently the container can only be partly compressed by the displacement.

It is furthermore particularly preferable from the production point of view and with respect to the construction space for the swellable substance chamber to be connected to the container, in particular formed on this in one piece. As a result, the liquid reservoir and the swellable substance chamber containing the swellable substance form a particular compact unit which is easy to handle.

It is furthermore particularly advantageous that the swellable substance chamber has a preferably membrane-like wall which can curve outwards as a result of the increase in volume of the swelling swellable substance. This wall, for this, can be e.g. elastically deformable. However, it can also be e.g. foldable and flexibly limp in construction. Such a wall transmits, without moving components, the volume work to the subsequent devices to be charged therewith, for example an active compound reservoir. Superabsorbers or liquid, osmotically active substances are suitable, for example, as the swellable substance. Superabsorbers are particularly well-suited as the swellable substance, because they have a very high affinity for water, but are not hygroscopic. A swelling hydrogel or a swelling polymer network which can be adjusted exactly with respect to their swelling properties can be employed, for example, as superabsorbers. A sodium chloride solution, for example, can be used as an osmotically active swellable substance. With respect to suitable swellable substances which are known to the person skilled in the art, reference may be made in particular to DE 103 00 896, the paper by Richter, A. et al., "Adjustable Low Dynamic Pumps Based on Hydrogels", published in Macromol. Symp. 2004, p. 377-384, the laid-open specification US 2010/030156 and the papers by Deem, T. et al., Osmotic dispense pump for operation at different temperatures and pressures", published in Sensors and Actuators A-Physical 136 (2007), no. 2, p. 742-748, ISSN/ISBN 0924-4247 and by Ehwald, M. et al., "A long- term stable and adjustable osmotic pump for small volume flow based on principles of phloem loading", published in Biotechnology and Bioengineering 94 (2006) , no. 1 , p. 37- 42, ISSN/ISBN 0006-3592. The swelling agent is usually a liquid, e.g. water, typically distilled water, e.g. doubly distilled water (Dl water). In both cases means can be provided for delaying the start of the swelling operation. These can be, for example, a dissolvable coating, which is impermeable to liquid, of sugar, salt, starch, soluble polymers or the like on a semipermeable membrane in the flow path to the swelling agent, and which is dissolved in a defined manner by the liquid emerging from the liquid reservoir. Only subsequently is passage of the liquid in the direction of the swellable substance possible. If a solid, granular superabsorber is used, a soluble coating on the swellable

substance granules is possible. By mixing various swelling and/or differently coated granules, swelling with a swelling rate which varies with respect to time can moreover also be caused, which can be used, for example, to give a pulsed release of an active compound. The device according to the invention is preferably used in combination with the device known from German Patent Application 10 2008 057 822.3 for storage and dermal administration of a substance, in particular as the dosing system mentioned there or as a component of this dosing system, in particular as a component of the upper part of the dosing system. The device according to the invention can exert pressure on the first chamber of the device there, and as a result advantageously drive out the substance present in the first chamber or the solvent present therein. It can also advantageously, by exertion of a pressure on the first chamber, open a separable weld which separates the first chamber of the device for storage and dermal administration of a substance from a second chamber of this device.

Brief description of the figures

The invention is explained in more detail in the following with the aid of diagrammatic drawings of several embodiments with further details.

These show:

Fig. 1 : a diagram of the construction of a device according to the invention;

Fig. 2: a device according to the invention in the starting state (Fig. 2a), initiation of the swelling operation (Fig. 2b) and after swelling of the swellable substance (Fig. 2c);

Fig. 3 a further device in the starting state (Fig. 3a), on initiation of the swelling operation (Fig. 3b) and after swelling of the swellable substance (Fig. 3c);

Fig. 4 another device according to the invention in the starting state

(Fig. 4a) and on initiation of the swelling operation (Fig. 4b); Fig. 5: a device according to another embodiment of the invention in the starting position;

Fig. 6: a check valve suitable for use in the devices according to Fig. 3

Fig. 5, in the blocking (Fig. 6a) and opened (Fig. 6b) state; and

Fig. 7: a device according to the invention in the starting state (Fig. 7a) and on initiation of the swelling operation (Fig. 7b);

Detailed description of the invention with the aid of several embodiment examples

The places and directions given relate to the representations chosen in the following figures and can change accordingly if the installation situations deviate therefrom.

The device 1 shown in diagram form in Fig. 1 comprises a first chamber 2 in the form of a liquid reservoir 3, which in the starting state is separated from the intermediate chamber 4 by a separating device 5 in the form of a breakable seal 6. The intermediate chamber 4 is joined in a flow connection via a release point 7 to the part 8 of the swellable substance actuator which performs the volume work. After the breakable seal has been broken open, the flow path between the liquid reservoir 3 and intermediate chamber 4 is opened, so that the liquid, e.g. distilled water, stored in the liquid reservoir 3 can enter into the intermediate chamber 4 from the first chamber 2, and is fed from there via the release point to the swellable substance. This leads to an increase in volume in part 8 of the swellable substance actuator, which can be used to drive devices coupled to this, for example for release of active compounds, such as insulin.

Alternatively, the separating device 5 can comprise a combination of breakable seal and check valve. This is advantageous in particular if the volume of the intermediate chamber 4 can be greatly increased. In this case, after opening the breakable seal the user forces the contents of chamber 2 through the check valve completely into the intermediate chamber 4. After this operation, the chamber 2 can be removed. The chamber 2 can therefore also comprise e.g. a syringe in this case.

In the device 1 according to Fig 2, the swellable substance 9 is provided in a swellable substance chamber 10, which apart from an elastic membrane 1 1 on the under-side, is produced from a dimensionally stable material. Instead of a membrane 1 1 of an elastic material, a membrane 1 1 of a folded film having tensile strength, for example, can also be used. Above the swellable substance chamber 10 and connected to this a container 12 which is likewise dimensionally stable is provided, which accommodates a bag-like component 13 forming two chambers 2, 4. The first chamber 2, which is larger in the starting state, forms a liquid reservoir 3 for the liquid triggering the swelling operation. The second intermediate chamber 4, which is smaller in the starting state, is separated spatially and in a liquid-tight manner from the first chamber 2 in the starting state according to Fig. 2a via a separating device 5 in the form of a breakable seal 6. The intermediate chamber 4 is joined in a flow connection via an opening 14 in the wall 15 between the swellable substance chamber 10 and container 12 to a flat distance layer 16, which in its turn is separated from the swellable substance 9 in a manner which is permeable to liquid but essentially impermeable to the swellable substance 9 by a similarly flat filter 17. In this context, the opening 14, distance layer 16 and filter 17 form the release point 7 of the device 1 . The distance layer 16 can be constructed, for example, like a frame or sponge, but can also be a spacer knitted fabric of a rigid, wire-like material of plastic. Wide-mesh filter cloths are furthermore suitable for constructing the distance layer 16. In addition to the supporting action, the distance layer 16 can in principle also have a liquid-transporting function. By its use, the effective cross-sectional area through which the liquid is fed to the swellable substance 9 is kept as large as possible. Woven fabrics of fibres of plastic or highly compressed nonwoven materials are suitable, for example, as the filter 17. The swellable substance chamber 10 accommodating the swellable substance 9 furthermore has vent openings 18 in the embodiment example.

The upper region 19 of the container wall is lid-like and similarly dimensionally stable in construction. The region 19 is provided displaceably relative to the remainder of the container 12, namely can be rotated around a joint 20. The walls of the container 12 away from the joint are at a distance from the lid-like region 19 via a gap 21 such that the lid-like region 19 can be swivelled downwards in the direction of the liquid reservoir 3 under the action of a force directed on to the region 19 from the top. The swivelling movement is limited by arrival at a stop 22. In the initial state according to Fig. 2a, however, the swivelling movement is blocked by a separable blocking body 23 arranged in the gap 21 , which

suppresses unintentional activation of the swelling operation. If required, the blocking body 23 also prevents a rotating movement of the lid-like region 19 in the opposite direction with the liquid reservoir inserted in the container 12, so that the device 1 can be transported and handled in the starting state without problems.

After removal of the blocking body (Fig. 2b), the lid-like region 19 of the container 12 can be rotated in the direction of the liquid reservoir 3 by an appropriate action of force until it comes into contact with the stop 22 (arrow A). As a result, a defined pressure is generated in the liquid reservoir 3, under the action of which the breakable seal 6 breaks open and opens up a flow path from the liquid reservoir 3 to the intermediate chamber 4. The second intermediate chamber 4 provided in the bag-like component 13 thereby increases in size considerably and as a result releases the pressure in the liquid again. The liquid can now seep through the bore-like opening 14 into the distance layer 16, where it is distributed in a planar manner and arrives, through the filter 17, in contact with the swellable substance 9. This subsequently absorbs (Fig. 2c) the liquid stored in the bag-like component 13, for example by osmotic forces, and thereby expands three-dimensionally, the volume of the bag-like component 13 becoming smaller to compensate the shrinking volume of liquid. Since the walls of the bag-like component 13 have a relatively high tensile strength and are therefore not elastically pre-extended, they generate no force driving the liquid in the direction of the swellable substance 9. On the other hand, due to their flexibly limp construction also no noticeable forces are necessary to collapse or fold up the bag-like component 13. The expanding swellable substance 9, in contrast, slowly arches outwards in a controlled manner the membrane 1 1 provided on the under-side of the swellable substance chamber 10. As a result, work can be performed in a coupled-on apparatus.

As a result of the increasing pressure in the swellable substance 9, small amounts of the swellable substance 9 can be forced locally through the filter 17.

Figures 7a and 7b show a device which is slightly modified compared with the embodiment of Figures 2a and 2b, in which the upper container wall 19 is equipped with a buffer edge 36, the actuation impinges on a part of the component 13 in order to reduce the volume of the chamber 2 with the liquid reservoir 3, to break open the breakable seal 6 due to the pressure thereby arising and to open up a flow path from the liquid reservoir 3 to the intermediate chamber 4.

Superabsorbers (e.g. manufactured by BASF, Evonik or Sumitomo) or liquid, osmotically active materials can be employed, for example, as the swellable substance 9. In both cases means can be provided for delaying the start of the swelling operation. In the case of an osmotically active liquid, this can be, for example, a dissolvable coating on the filter 17 which is impermeable to liquid and is dissolved in a defined manner by the liquid emerging from the liquid reservoir 3. Only subsequently is passage of the liquid in the direction of the swellable substance 9 possible. If a solid superabsorber is used instead of such a coating on the filter 17, a soluble coating on the swellable substance granules is also possible. By mixing various swelling and/or differently coated granules, a pulsed swelling can moreover also be caused, which can be used, for example, to give an intermittent release of an active compound.

In the device shown in Fig. 3a, the liquid reservoir 3 and the intermediate chamber 4 are provided in two bag-like components 13', 13" which are separate from one another, and for simplification of the diagram are without a surrounding container and are connected to the swellable substance chamber 10 accommodating the swellable substance 9. The component 13' storing the liquid required for the swelling again comprises a flow path to the intermediate chamber 4 which is closed by a breakable seal 6. The second bag-like component 13" comprises an upper film layer 26 and a lower film layer 26' which are joined to one another at the edge via weld seams 27. A vacuum prevails in the component 13", as a result of which this contracts in a bellows-like manner. A check valve 24 with an opening 14' opening into the check valve 24 and an opening 14" opening out of the check valve 24 is furthermore provided between the liquid reservoir 3 and the

intermediate chamber 4 downstream of the breakable seal 6. The swellable substance 9 is separated from the intermediate chamber 4, which is inserted into a recess in the lower film layer 26', by a membrane-like, semipermeable filter 17 and a soluble layer 25 covering this upstream. A disc of caramelized sugar, for example, can serve as the soluble layer 25.

To activate the swelling operation, the breakable seal 6 is opened by a pressure exerted on the liquid reservoir 3. As a result of further pressure on the liquid reservoir 3, liquid enters into the intermediate chamber 4 through the check valve 24 and acts on the soluble liquid-tight layer 25 (Fig. 3b). A groove-like separating aid 28 (only shown in Fig. 3a) set in the outer wall of the component 13' in the region of the breakable seal 6 serves as an intentional breaking point to remove the liquid reservoir 3, which is now no longer required, the check valve 24 preventing the liquid from flowing back. After a predetermined time, the liquid-tight layer 25 is dissolved, so that the liquid comes into contact with the swellable substance 9 and the increase in volume in the swellable substance 9 starts in the manner described above and leads to arching of the membrane 1 1 outwards. The intermediate chamber 4 which has meanwhile been filled full with liquid is subsequently emptied again and contracts again in a bellows-like manner

(Fig. 3c). Fig. 4a shows a similar embodiment of the invention in which, however, the intermediate chamber 4 is not enclosed in a bag-like manner. In this case, the component 13" is formed by a thermoformed film 29. It is capable of compensating the changes in the volume of liquid in the intermediate chamber 4, optionally also by wrapping over a bistable contour of the film 29 (Fig. 4b).

In the embodiment example according o Fig. 5, a soluble solid body 30 blocking the flow path is arranged before the opening 14 between the intermediate chamber 4 and the swellable substance 9. After the breakable seal 6 has been broken open, the solid body is initially dissolved by the entering liquid and, after dissolving, releases the flow path again, so that the liquid can come into contact with the swellable substance 9.

In principle, in the embodiments according to Fig. 3 to 5 it would also be conceivable to feed the liquid into the intermediate chamber 4 by any desired container which can be emptied from the outside, for example by a syringe. Vent bores 18 (shown only in Figures 2a and 2b) can likewise also be provided in these embodiment examples. If the soluble layer 25 or the soluble solid body 30 is not capable of holding the vacuum in the intermediate chamber 4, the vent bores 18 must be sealed during storage.

Fig. 6 shows a possible construction of the check valve used in the devices described above. It comprises a rigid plate 31 with an opening 32, which forms a part of the flow path for the liquid emerging from the liquid reservoir 3. A piece of film 33, preferably an elastomer film, is sealed on to the downstream flat side of the plate 31 by means of a weld seam 34 surrounding the entire circumference of the opening 32. The piece of film 33 is provided with a cut 35 which is displaced relative to the opening 32. Under an increased pressure acting upstream on the check valve 24 (Fig. 6b), the piece of film 33 lifts up, as a result of which liquid can pass through the opening 32, the space between the piece of film 33 and plate 31 and the cut 35. Under an increased pressure on the downstream surface of the plate 31 , on the other hand (Fig. 6a), the piece of film 33 lies tightly over the opening 32 and prevents the liquid from flowing back.

The features disclosed in the above description, the claims and the drawings can be of importance both individually and in any desired combination for realizing the invention in its various embodiments.

Claims

Device (1 ) for generating a volume work which can be driven by a swellable substance (9), preferably for a delivery apparatus for delivering a medicinal active substance, with a swellable substance chamber (10) of variable volume which is filled with a swellable substance (9) and can be brought into a flow connection with a liquid reservoir (3) of variable volume,

characterized in that

before initiation of the swelling operation the flow connection between the liquid reservoir (3) and swellable substance chamber (10) is interrupted by at least one barrier (6, 24) which opens when a predetermined opening pressure arises at the barrier (6, 24).

Device according to claim 1 , characterized in that

the barrier or at least one of the barriers is a breakable seal (6).

Device according to claim 1 or 2, characterized in that

the barrier or at least one of the barriers is a pretensioned valve (24).

Device according to one of the preceding claims, characterized in that the flow connection between the liquid reservoir (3) and swellable substance chamber (10) is interrupted by a check valve (24).

Device according to one of the preceding claims, characterized in that an intermediate chamber (4) is mounted upstream of the swellable substance chamber (10) in the flow connection between the liquid reservoir (3) and swellable substance chamber (10).

Device (1 ) according to one of the preceding claims, characterized in that a means, which can be removed by the liquid emerging from the liquid reservoir (3), for delaying the swelling operation is provided in the flow path to the swellable substance (9).

7. Device according to one of the preceding claims, characterized in that a flat spacer (16) extends in the flow path between the liquid reservoir (3) and swellable substance chamber (10).

8. Device according to claim 7, characterized in that

a flat filter (17) is arranged between the spacer (16) and the swellable substance (9) present in the swellable substance chamber (10). 9. Device according to claim 8 or 9, characterized in that

the flat spacer is porous.

Device (1 ) for generating a volume work which can be driven by a swellable substance (9), preferably for a delivery apparatus for delivering a medicinal active substance, with a swellable substance chamber (10) of variable volume which is filled with a swellable substance (9) and can be brought into a flow connection with a liquid reservoir (3), in particular according to one of the preceding claims, characterized in that

the liquid reservoir (3) is bag-like and the wall of the bag-like liquid reservoir (3) is preferably of a construction which is flexibly limp but has tensile strength.

Device according to one of the preceding claims, characterized in that means (21 ) are provided which limit the change in volume of the liquid reservoir (3) which can be achieved by exertion of force from the outside.

Device according to one of the preceding claims, characterized in that the bag-like liquid reservoir (3) is arranged entirely or partly in a

dimensionally stable container (12).

13. Device according to claim 12, characterized in that

the container (12) is equipped with means for transferring pressure to the liquid reservoir (3). 14. Device according to claim 13, characterized in that

the means for transferring pressure comprises a region (19) of the container wall arranged displaceably.

15. Device according to claim 14, characterized in that

the displaceable region (19) of the container wall is connected rotatably to the remainder of the container (12).

16. Device according to claim 14 or 15, characterized in that

the displacement is limited by a stop (22).

17. Device according to one of claims 12 to 16, characterized in that

the swellable substance chamber (10) is connected to the container (12), in particular formed on this in one piece. 18. Device according to one of the preceding claims, characterized in that the swellable substance chamber (10) has an elastic deformable membrane (1 1 ) which can curve outwards as a result of the increase in volume of the swelling swellable substance (9). 19. Delivery apparatus with a device (1 ) according to one of the preceding

claims, in particular for a medicinal active substance.