Method for producing an analysis element spreading layer

1. A method for producing an analysis element spreading layer, which is implemented for absorbing a liquid to be analyzed in an analysis element and distributing it uniformly over a liquid outlet side of the analysis element spreading layer, the method comprising the following steps:

supplying a porous starting membrane having a top side, a bottom side and a starting thickness D between the bottom side and the top side, the size of the pores of the starting membrane increasing at least sectionally over its starting thickness D,

selecting a predefined distance within the starting thickness D of the starting membrane parallel to the top side of the starting membrane corresponding with a desired mean pore size;

cutting the starting membrane at the predefined distance in such a manner that a sublayer of the starting membrane is removed, wherein

the analysis element spreading layer is a sublayer of the starting membrane, having a thickness d that is less than the starting thickness D of the starting membrane,

the pores of the analysis element spreading layer are in fluid connection to one another in such a manner that the analysis element spreading layer is permeable to a liquid,

the membrane surface formed by the removal of a sublayer of the starting membrane is the liquid outlet side of the analysis element spreading layer, and

the mean pore size of the pores on the liquid outlet side of the analysis element spreading layer is at least 1μm and

supplying the analysis element spreading layer formed to a test field having a reaction layer with at least one reagent, which is part of a reagent system for detecting an analyte in the liquid sample.

2. The method according to claim 1 , wherein a sublayer is only removed on the bottom side of the starting membrane, so that the top side of the starting membrane also forms a top side of the spreading layer, the side opposite to the top side being the liquid outlet side of the spreading layer.

3. The method according to claim 1 , wherein the starting membrane is fastened on an underlay and is moved jointly with the underlay as a material web to a cutting device, by means of which the starting membrane is cut.

4. The method according to claim 1 , wherein cutting the starting membrane comprises supplying a cutting device that comprises a deflection device, by which a material web containing the starting membrane is deflected during the production process, the starting membrane being cut upon passing the deflection device.

5. The method according to claim 4 , wherein the top side of the starting membrane is moved over the deflection device.

6. The method according to claim 1 , wherein the starting membrane, before the removal or during the removal of a sublayer, is impregnated with a liquid, preferably with water, an aqueous solution, or a molten water-soluble wax.

7. The method according to claim 6 , wherein the cutting device comprises a roller, and that the starting membrane impregnated with liquid will be frozen on a section of the roller in such a manner that, during the cutting, the starting membrane is frozen on the section of the roller and is moved with the roller.

8. The method according to claim 1 , wherein the starting membrane comprises an asymmetrical membrane.

9. The method according to claim 1 , wherein the mean pore size on the liquid outlet side of the spreading layer is at least 2 μm.

10. The method according to claim 9 , wherein the mean pore size on the liquid outlet side of the spreading layer is at most 20 μm.

11. The method according to claim 1 , wherein the mean pore size on the top side is at least 10 μm.

12. The method according to claim 11 , wherein the mean pore size on the top side is at most 60 μm.

13. The method according to claim 1 , wherein the free pore area on the liquid outlet side of the spreading layer is at least 70%.

14. A spreading layer of an analysis element for absorbing a liquid to be analyzed and for uniformly distributing the liquid over a liquid outlet side, by a method according to claim 1 , wherein

the spreading layer is a porous membrane, which has a top side opposite to the liquid outlet side, which forms a liquid inlet side;

the spreading layer comprises a plurality of pores, which are in fluid contact with one another in such a manner that the spreading layer is permeable to a liquid;

the mean pore size increases along the thickness d of the spreading layer in such a manner that the mean pore size on the liquid inlet side is greater than the mean pore size on the liquid outlet side;

the mean pore size on the liquid outlet side is at least 1 μm; and

the free pore area on the liquid outlet side of the spreading layer is at least 70%.

15. A method for producing an analysis element for analyzing a liquid sample, which comprises a test element and an analysis element spreading layer, comprising the following steps:

supplying a porous starting membrane having a top side, a bottom side, and a starting thickness D between the bottom side and the top side, the size of the pores of the starting membrane at least sectionally increasing over its starting thickness D,

selecting a predefined distance within the starting thickness D of the starting membrane parallel to the top side of the starting membrane corresponding with a desired mean pore size;

removing a sublayer of the starting membrane at the predefined distance parallel to the top side in such a manner that the analysis element spreading layer is a sublayer of the starting membrane having a thickness d, which is less than the starting thickness D of the starting membrane, wherein

the pores of the analysis element spreading layer are in fluid connection to one another in such a manner that the analysis element spreading layer is permeable to a liquid,

the membrane surface formed by the removal of a sublayer of the starting membrane is the liquid outlet side of the analysis element spreading layer, and

the mean pore size of the pores on the liquid outlet side of the analysis element spreading layer is at least 1μm,

supplying the analysis element spreading layer formed to a test field having a support layer and a test layer, wherein the test layer comprising a reaction layer having at least one reagent, which is part of a reagent system for detecting an analyte in the liquid sample,

applying the analysis element spreading layer to the test field in such a manner that the liquid outlet side of the analysis element spreading layer presses against a top side of the test layer, so that the analysis element spreading layer and the test field are connected and jointly form the analysis element.

16. The method according to claim 1 , wherein the analysis element spreading layer is provided as a hydrophilic membrane or is hydrophilized.