Device for administering a liquid medication

Description

Background of the invention

[0001] The invention relates to a device for administering a liquid medication. Description

[0002] Devices for administering liquid medication are known from the prior art, comprising a reservoir connected to a pump system. The outlet side of the pump is connected to a medication outlet, for example, to a tube or hose, or to an atomizer. The pump chamber of the pump often has an inlet and an outlet valve. The inlet valve closes the pump chamber precisely when the pump generates an output pressure to deliver the medication via the tube, hose, or atomizer, in order to prevent the medication from flowing back into the reservoir. To refill the pump chamber, a negative pressure is created in the pump chamber, whereby the medication flows from the reservoir through the opening inlet valve into the pump chamber, while the outlet valve closes to prevent the medication from flowing back from the tube, hose, or atomizer.The valves are thus designed as common one-way valves, for example, check valves. Similar devices are described in WO 2013 / 191011 A1, US Pat. No. 8,628,517 B2, and WO 2013 / 072790 A1.

[0003] WO 2012 / 007315 discloses a device for administering a liquid medicinal formulation which is located in a container inserted into the device and is dispensed from the device through at least one nozzle opening, wherein the liquid medicinal formulation flows through a micro-filter formed by a micro-structured component before flowing through the at least one nozzle opening.

[0004] Particularly in medical applications, it is often desirable for the device for administering the liquid medication to be as small as possible and thus take up little space. However, the inlet and outlet valves known from the prior art, which are usually purely mechanical, cannot be made smaller indefinitely, so there is a need to further improve such valves, or perhaps even eliminate them altogether.

[0005] It is therefore the object of the invention to propose a generic valve and a corresponding device for administering a liquid medication, which have the smallest possible dimensions.

[0006] This object is achieved according to the invention by a device having the features of patent claim 1. The dependent claims 2 to 14 each relate to advantageous embodiments of the invention.

[0007] The invention relates to a device for administering a liquid medication, comprising a reservoir in which a medication is stored or can be stored, and comprising a pump having a pump chamber which is fluidically connected to the reservoir via a one-way valve permeable only in the direction from the reservoir into the pump chamber, and which is fluidically connected to a medication outlet via a valve according to the invention.

[0008] The valve according to the invention comprises a valve body that includes an interior space for receiving a liquid, in particular a liquid medicament. The valve body has a liquid inlet and an opposite liquid outlet, both of which open into the interior space. A plurality of microchannels are arranged in the interior space, extending in the connecting direction between the liquid inlet and the liquid outlet.

[0009] The valve according to the invention makes use of the capillary effect. It is known that liquids can wet surfaces and move through complex structures due to capillary forces. The energy required for liquid movement is determined by the difference in the atomic forces of attraction between the liquid atoms inside the liquid and the atomic forces of attraction between the liquid atoms located at the liquid surface and thus at the interface between the liquid and a gas. The interface between a liquid and a gas is also referred to as the free surface. Likewise, energy must be expended to remove liquid atoms from the free surface, so that previously deeper-lying atoms located inside the liquid form the free surface. A force must therefore be exerted to remove liquid components from strongly wetting surfaces.

[0010] The valve body forms a fluid channel defined by side walls. The side walls can be parallel side walls of a polygonal or round, for example, circular, channel in cross-section.

[0011] The interior space has a cross-sectional area that is larger than a cross-sectional area of the microchannels, wherein a cross-sectional area ratio between the microchannels and the interior space is preferably between 1:5 and 1:1000, and particularly preferably between 1:50 and 1:100. The microchannels preferably have a diameter between 1 µm and 200 µm, and particularly preferably between 5 µm and 20 µm.

[0012] According to the invention, the microchannels are formed by a grid of parallel, rod-shaped boundary elements, or by several parallel, mutually offset layers of a grid of parallel, rod-shaped boundary elements. The boundary elements can extend perpendicular to the connecting direction between the liquid inlet and the liquid outlet. The boundary elements preferably have a round, in particular circular, or a polygonal cross-section. The boundary elements can, for example, have a diameter between 0.5 µm and 50 µm, preferably between 3 µm and 15 µm. The length of the boundary elements can range from a few µm to the full diameter of the interior of the valve body; more preferably, the length of the boundary elements is between 20% and 80% of the interior diameter perpendicular to the connecting direction between the liquid inlet and the liquid outlet.For this purpose, the limiting elements can extend from an inner side of the side wall defining the interior of the valve body toward an opposite side wall without reaching it, so that a gap is formed between the limiting elements and the respective opposite side wall. This embodiment is also characterized in particular by its ease of manufacture.

[0013] To increase the adhesion between the boundary elements and a liquid, one embodiment of the invention provides for the surface of the boundary elements to have a functional coating, for example, a hydrophilic coating. For this purpose, the channel interior can also be hydrophobically coated.

[0014] According to the invention, the interior, the fluid inlet, and the fluid outlet have the same cross-sectional area perpendicular to the connection direction. This results in a particularly compact and easily manufactured valve geometry.

[0015] In this case, the valve body can be provided with parallel side walls whose inner sides define the interior space, with the side walls opening into the liquid inlet and the liquid outlet at opposite ends. A valve that is easy to manufacture is achieved by the fact that, in the latter embodiment, the valve body has a constant cross-section over its entire length between the liquid inlet and the liquid outlet.

[0016] The valve body can have a round, in particular circular, or a polygonal cross-section. Short description of the characters

[0017] Further details of the invention are explained with reference to the following figures. Figure 1 shows a schematic longitudinal cross-section through an embodiment of the valve according to the invention without applied negative pressure; Figure 2 shows a schematic longitudinal cross-section of the valve according to Figure 1 with applied negative pressure P1 > 0;and Figure 3 a schematic longitudinal cross-section of the valve according to the Figures 1 and 2 with applied negative pressure P2 > P1•

[0018] In the Figure 1In the valve shown, the valve body 1 is shown in longitudinal cross-section. The valve body 1 is delimited by opposite parallel side walls 7. The side walls 7, with their inner sides 8, delimit an interior space 2 in which a liquid 20, for example a medicament, is received. A liquid inlet 3 and a liquid outlet 4 are formed on opposite sides of the valve body 1. The liquid inlet 3 and the opposite liquid outlet 4 have exactly the same cross-section as the rest of the valve body 1, in particular as the interior space 2. A pump with a pump chamber of a device for administering a liquid medicament, for example, can be connected to the liquid outlet 4.

[0019] The valve body 1 can, for example, have a circular cross-section, or a polygonal one, for example a rectangular one and in particular a square one. Figure 1The boundary elements 6 shown in cross-section are rod-shaped lattice struts extending parallel to one another and perpendicular to the plane of the drawing. Two adjacent boundary elements 6 form a microchannel 5 between them, which extends in the connecting direction x between the liquid inlet 3 and the liquid outlet 4 and is open toward both inlets 3, 4.

[0020] As in Figure 1 As shown, the microchannels are formed by several parallel, offset layers of a grid of parallel, rod-shaped boundary elements.

[0021] If there is no negative pressure at the liquid outlet 4 (Po= 0), the liquid 20 forms, as in Figure 1 shown, a substantially flat free surface between itself and the gas 30.

[0022] Only when1 a negative pressure (P1 > 0) is applied to the liquid outlet 4 (see Figure 2), the free surface between the liquid 20 and the gas 30 forms a concave geometry. With increasing negative pressure, the radius of the concave interface between the liquid 20 and the gas 30 decreases. In Figure 3 the case is shown where P2 > P1.

[0023] The radius of curvature of the free surface depends on the so-called Laplace pressure. This pressure increases with decreasing interface radius. Therefore, if the negative pressure exceeds the value for the Figures 1 to 3 If the pressure exceeds the maximum Laplace pressure valid for the microchannel structure shown, the liquid is transported out of the valve body 1. The valve according to the invention is therefore particularly suitable for use as an outlet valve in a generic device for administering a liquid medication.

[0024] In principle, the Laplace pressure increases proportionally to the surface tension of the liquid. Therefore, in order to adjust the threshold for the negative pressure at which the liquid is transported out of the valve body 1 to a specific value for a given surface tension, it may be necessary to adjust the diameter of the microchannels 5, and thus the distance between the boundary elements 6, accordingly.

[0025] The Figures 1 to 3 The embodiment shown can, for example, have an interior diameter perpendicular to the inner sides 8 of the side walls of between approximately 1 µm and 500 µm. This diameter is preferably between 10 µm and 100 µm.

[0026] The diameter of the microchannels 5, and thus the free spacing or clearance between the boundary elements 6, can be between 0.5 and 50 µm. Preferably, the free spacing or clearance between the boundary elements 6 is between 3 and 15 µm.

[0027] The valve according to the invention has the advantage that the required structures can be produced using common microstructuring processes, for example using micro-injection molding or silicon etching processes. List of reference symbols

[0028] 1Valve body 2Interior 3Liquid inlet 4Liquid outlet 5Microchannel 6Restriction element 7Side wall 8Inside xConnection direction between the liquid inlet and the liquid outlet

Claims

1. Device for administering a liquid medicament, having a reservoir in which a medicament is held or can be held, and having a pump with a pump chamber which is fluidically connected to the reservoir via a one-way valve allowing medium to pass through only in the direction from the reservoir into the pump chamber and which is fluidically connected to a medicament outlet via a valve, wherein the valve has a valve body (1) which has an inner space (2) for receiving a liquid (20), wherein the valve body (1) has a liquid inlet (3) and, opposite the latter, a liquid outlet (4), which both open into the inner space (2), wherein a multiplicity of microchannels (5) are arranged in the inner space (2), said microchannels (5) extending in connection direction (x) between the liquid inlet (3) and the liquid outlet (4), wherein the microchannels are formed from a grid of parallel, rod-shaped boundary elements (6), or from a plurality of parallel, mutually offset layers of a grid of parallel, rod-shaped boundary elements (6), wherein all of the parallel, rod-shaped boundary elements (6) in the valve body (1) are arranged in the inner space (2), characterized in that the inner space (2), the liquid inlet (3) and the liquid outlet (4) have the same cross-sectional area perpendicular to the connection direction (x).

2. Device according to Claim 1, wherein the valve is an outlet valve.

3. Device according to Claim 1 or 2, wherein the inner space has side walls with inner faces (8), with an inner-space diameter perpendicular to the inner faces of between 1 µm and 500 µm, preferably of between 10 µm and 100 µm.

4. Device according to any one of Claims 1 to 3, wherein the microchannels (5) have a diameter of between 1 µm and 200 µm and preferably of between 5 µm and 20 µm.

5. Device according to any one of Claims 1 to 4, wherein the diameter of the microchannels (5) is between 0.5 µm and 50 µm, preferably between 3 µm and 15 µm.

6. Device according to any one of Claims 1 to 5, wherein the boundary elements (6) extend perpendicular to the connection direction (x) between the liquid inlet (3) and the liquid outlet (4).

7. Device according to any one of Claims 1 to 6, wherein a length of the boundary elements (6) measures between 20% and 80% of the diameter of the inner space (2) perpendicular to the connection direction between liquid inlet (3) and liquid outlet (4), wherein the boundary elements (6), starting from an inner face (8) of the side wall (7) bordering the inner space (2) of the valve body (1), extend in the direction of an opposite side wall (7), without reaching the latter, such that a spacing between the boundary elements (6) and the respectively opposite side wall (7) is formed.

8. Device according to any one of Claims 1 to 7, wherein the boundary elements (6) have a round, in particular circular, cross section or a polygonal cross section.

9. Device according to any one of the preceding claims, wherein the valve body (1) has parallel side walls (7) whose inner faces (8) delimit the inner space (2), wherein the side walls open at opposite ends into the liquid inlet (3) or the liquid outlet (4).

10. Device according to Claim 9, wherein the valve body (1) has a constant cross section along its entire length between the liquid inlet (3) and the liquid outlet (4).

11. Device according to any one of the preceding claims, wherein the valve body (1) has a round, in particular circular, cross section or a polygonal cross section.

12. Device according to any one of the preceding claims, wherein, in order to increase the adhesion between the boundary elements (6) and a liquid, the surface of the boundary elements (6) has a functional coating, preferably a hydrophilic coating.

13. Device according to any one of the preceding claims, wherein the cross-sectional area ratio between the microchannels (5) and the inner space (2) is between 1:5 and 1:1000, preferably between 1:50 and 1:100.

14. Device according to any one of the preceding claims, wherein the required structures of the valve are produced by micro-injection moulding or silicon etching processes.