WO2017085372A1 - Rigid filtration unit including compression projections - Google Patents

Abstract

The invention relates to a filtration unit (1) for filtering a fluid, including a rigid housing formed of a first housing element (2) and a second housing element (3) between which is arranged a filtration medium (4), said filtration medium having a maximum thickness (Em) in said housing, the first housing element (2) and the second housing element (3) including first and second inner projections (14, 15), respectively, which extend in the housing, said inner projections (14, 15) being arranged to compress the filtration medium along the periphery thereof to an inner thickness (Ei) that is smaller than the maximum thickness (Em), the first and second housing elements (2, 3) further including first and second outer projections (16, 17), respectively, which extend in the housing, said outer projections being arranged to compress the filtration medium (4) to an outer thickness (Ee) of between 80% and 110% of the inner thickness (Ei).

Description

 Rigid filtration unit including compression protrusions

The invention relates to a filtration unit for filtering a fluid and a bag system comprising such a filtration unit.

The invention applies to the field of filtration and in particular the filtration of a biological fluid such as blood or blood components.

In the field of transfusion, it is conventional to treat the blood to remove undesirable substances such as leukocytes, pathogens, certain proteins - for example the prion - and / or substances used in inactivation processes, reduction and / or elimination of pathogens.

In order to eliminate these undesirable substances, there are two categories of filtration units: the so-called flexible filtration units comprising a flexible outer casing, and the so-called rigid filtration units comprising a rigid casing. A filtration medium capable of removing undesirable substances from the fluid is enclosed in these filtration units.

In transfusion in particular, it is important that all of the fluid to be filtered passes through the filtration medium without bypassing it. Indeed, a single drop of unfiltered blood in a unit of filtered whole blood is sufficient to increase the amount of leukocytes so as to exceed the accepted standards. WO 2015/050213 discloses a filtration unit comprising a rigid housing provided with flat clamping parts compressing the filtration medium to a predetermined thickness. However, by excessively compressing the periphery of the filtration medium, it can be damaged, creating preferential passages harmful to the efficiency of filtration.

EP-A1-0 329 303 discloses a filtration unit comprising a rigid housing formed of two half-shells between which a filtration medium is disposed. To ensure the seal between the housing and the filtration medium, this document proposes to use a filter medium of circular shape and having a diameter greater than 0.1% to 1% to the inside diameter of the housing. The seal is thus obtained by tight fit. In US 2005/0056580, the filtration unit also comprises a rigid housing formed of two parts assembled together and incorporating a filtration medium. In order to seal, each of the housing parts is provided with a sealing ring which compresses the filtration medium and thus prevents the fluid to be filtered from bypassing this filtration medium. To more effectively avoid this risk of bypassing, it is also envisaged to inject a sealing material, such as an EVA wax mixture, into the space formed between the peripheral end of the filtration medium and the housing. This solution is however complex to implement. The invention proposes a rigid type of filtration unit reducing the risk that the fluid to be filtered bypasses the filtration medium, without constraint of form and easy to manufacture.

Thus, according to a first aspect, the invention relates to a filtration unit for filtering a fluid comprising a rigid housing formed of a first housing element and a second housing element between which a filtration medium is arranged to define an inlet compartment for the fluid to be filtered and an outlet compartment for the filtered fluid, said housing having an inlet opening into the inlet compartment and an outlet opening opening into the compartment of outlet, said filtration medium having a maximum thickness Em in said housing, the first housing element and the second housing element respectively comprising first and second inner projections extending into the housing, said inner projections being arranged to compress the housing; filtration medium along its periphery according to an inner thickness Ei less than the thick E maximum Em to create an inner fluid sealing area, the first and second housing member further comprising respectively a first and a second outer projection extending into the housing, said protrusions outer projections being located externally to said inner projections, said outer projections being arranged to compress the filter medium to an outer thickness Ee which is between 80% and 1 10% of the inner thickness Ei so as to create an outer sealing zone at fluid.

According to a second aspect, the invention proposes a bag system for filtering a fluid, comprising:

 a filtration unit according to the first aspect of the invention and

 a bag for collecting the filtrate, said collection bag being connected, via a tubing, to the outlet orifice of the filtration unit.

Other objects and advantages will become apparent from the following description with reference to the appended figures in which: FIG. 1 represents a diagrammatic and exploded view of a filtration unit according to the invention; FIG. 2 represents a schematic cross-sectional view of a filtration unit according to the invention; Figures 3 and 4 show a schematic and partial view of the filter unit of Figure 2; Figure 5 shows a schematic view of an alternative embodiment of the inner and outer projections of a filter unit according to the invention; Figures 6 and 7 show a schematic perspective view of the first and second housing element respectively of a filter unit according to the invention; and FIG. 8 is a schematic view of a bag system comprising a filtration unit according to the invention. According to a first aspect, the invention relates to a filtration unit for filtering a fluid.

In particular, the filtration unit is intended to remove target components from blood or a blood component such as a plasma including a platelet-rich plasma and a platelet-poor plasma, a red blood cell concentrate or a concentrate. platelets.

The target components are in particular leukocytes, prion proteins or pathogen inactivation substances such as methylene blue.

According to FIGS. 1 and 2, the filtration unit 1 of the invention comprises a rigid housing formed of a first housing element 2 and a second housing element 3 between which a filtration medium 4 is arranged so that defining an inlet compartment 5 for the fluid to be filtered and an outlet compartment 6 for the filtered fluid.

In FIG. 2, the inlet compartment 5 is limited by the first housing element 2 and the filtration medium 4. The outlet compartment 6 is limited by the second housing element 3 and the filtration medium 4.

This filtration filtration unit 1 is intended to filter a fluid which is, for example a biological fluid such as blood or a blood component. In one embodiment, the filtration medium 4 is a leukocyte depletion medium. The filtration medium comprises in particular one or more layers of a woven or non-woven material.

The material (s) forming the layer (s) of the leukocyte removal medium are chosen from the group comprising polymers or copolymers based on polypropylene, polyester, polyamide, high or low density polyethylene. , polyurethane, polyvinylidene fluoride, polyvinylidene polyvinylpyrrolidone and their derivatives. Advantageously, the material is polypropylene, polyethylene terephthalate or polybutylene terephthalate.

The housing further includes an inlet opening 7 opening into the inlet compartment 5 and an outlet opening 8 opening into the outlet compartment 6.

In particular, the first housing element 2 comprises the inlet orifice 7 and the second housing element 3 comprises the outlet orifice 8. These inlet and outlet ports 7, 8 are advantageously molded in the first and second elements. 2.3 housing respectively.

In FIGS. 2 and 4, in order to allow a better emptying of the filtration unit 1, the outlet orifice 8 is provided with a flow restriction 9 formed by a reduction in the diameter of the outlet orifice 8. By Venturi effect, the flow restriction 9 creates an acceleration of the flow of filtered fluid which tends to draw the fluid outside the filtration unit 1.

The first housing member 2 and the second housing member 3 are sealingly joined at their periphery so as to form a fluid-tight housing.

For example, the first and second housing members 2,3 are assembled together by high frequency, radio frequency or ultrasonic welding. Alternatively, the housing elements 2,3 are assembled by gluing.

In order to facilitate the assembly of the two housing elements 2,3, the housing elements are fitted together by means of a form-fitting or snap-fitting connection. As illustrated in FIGS. 3 to 4, the first housing element 2 comprises a recess 10 which fits a protuberance 11 arranged on the second housing element 3. The rigid housing is made of a polymeric synthetic material, for example polycarbonate or polypropylene.

The filtration medium 4 is disposed between the two housing members 2,3, said filtration medium having a maximum thickness Em in said housing. The maximum thickness of the filtration medium in the housing corresponds to the largest value of the thickness of the filtration medium inside the housing.

According to one embodiment, the filtration medium 4 is held tight between the housing members 2,3. In this case, the maximum thickness Em of the filtration medium corresponds to the distance Hm separating the two housing elements 2, 3 (FIG. 5).

As shown in FIGS. 2 to 5 and in order to ensure fluid sealing between the inlet compartment 5 and the outlet compartment 6 of the filtration unit, the first housing element 2 and the second housing element 3 respectively comprise a first and a second inner projection 14,15 extending into the housing, said inner projections 14,15 being arranged to compress the filter medium along its periphery to an inner thickness Ei less than the maximum thickness Em so as to create an internal fluid sealing zone.

In the description and in relation to the filtration unit, the term "inside" is to be understood as opposed to the term "outside". A so-called "inside" element designates an element located in an area of the filtration unit closer to the center of the filtration unit than an "outside" element.

In relation to FIG. 5, the first inner projection 14 extends in the housing on a first internal height Hi1, measured from the bottom of the first housing element 2. The second inner projection 15 extends into the housing on a second interior height Hi2, measured from the bottom of the second housing element 3. In a particular form, the first interior height Hi1 and the second internal height Hi2 are substantially equal, so as to apply the same pressure on each side of the filtration medium.

The inner projections 14, 15 are arranged to compress the filtration medium along its periphery, i.e., the inner projections 14, 15 exert pressure on the filtration medium 4 on either side of the filtration medium. by reducing the thickness of said filter medium 4, thereby creating a narrowed passage between the inner projections 14,15 which stops or slows the fluid flowing through the filtration medium 4. This narrowed passage forms the inner sealing zone fluid, that is to say that the fluid does not normally pass through this zone.

In addition, the compression of the filtration medium caused by the internal projections 14,15 will reduce the permeability of said filtration medium, which contributes to the stopping or slowing of the fluid in the compressed zone.

The inner projections 14,15 are continuous around the periphery of the housing elements 2,3, compressing the filtration medium 4 continuously on its periphery.

The compression of the filtration medium 4 induced by the internal projections 14, 15 reduces the thickness of the filtration medium 4 to the inner thickness Ei.

The inner thickness Ei is the smallest distance between the first and second inner projections 14,15.

In relation to FIG. 5, the inner thickness Ei corresponds to the difference between the distance Hm separating the housing elements 2,3 and the sum of the internal heights Hi1, Hi2 of the inner projections 14,15.

In order to ensure fluid tightness, the inner thickness Ei of the filtration medium 4 represents between 35% and 55% of the maximum thickness Em of the filtration medium 4, in particular between 40% and 50% of the thickness. maximum Em from the middle of In a particular example, the inner thickness E 1 represents about 45% of the maximum thickness Em of the filtration medium 4 in the housing.

According to Figures 2 to 5, the first and second inner projections 14,15 are vis-à-vis. The vertices 14,15 inner peaks are facing or are slightly offset with respect to each other. When offset slightly, the offset is at most half the width of the inner projections 14,15. In a particular embodiment, the first and second inner projections 14,15 have substantially the same dimensions and geometry.

According to the invention and in connection with FIGS. 2 to 5, the first and the second housing element 2, 3 furthermore comprise respectively a first and a second external projection 16, 17 extending in the housing, said external projections being located externally to said inner projections 14,15, said outer projections being arranged to compress the filtration medium 4 to an outer thickness Ee which represents between 80% and 1 10% of the inner thickness Ei so as to create an outer zone of fluid tightness.

In relation to FIG. 5, the first outer projection 16 extends into the housing on a first outer height He1, measured from the bottom of the first housing member 2. The second outer projection 17 extends into the housing on a second external height He2, measured from the bottom of the second housing element 3.

In a particular form, the first external height He1 and the second external height He2 are substantially equal, so as to apply the same pressure on each side of the filtration medium.

Similar to the projections 14,15, the outer projections 16,17 are arranged to compress the filtration medium along its periphery, i.e. external projections 16,17 thus exert a pressure on the filtration medium 4 on each side of the filtration medium by reducing the thickness of said filtration medium 4, thus creating between the outer projections 16,17 a narrowed passage which stops the fluid s flowing through the filtration medium. This narrowed passage forms the outer fluid-tight zone, i.e. the fluid does not normally pass through this zone.

The outer projections 16,17 are continuous around the periphery of the housing elements 2,3, compressing the filtration medium 4 continuously on its periphery.

In addition, the compression of the filtration medium 4 caused by the external projections 16,17 will reduce the permeability of the filtration medium, which contributes to the stopping or slowing of the fluid in the compressed zone.

The compression of the filtration medium 4 induced by the outer projections 16,17 reduces the thickness of the filtration medium 4 to the outer thickness Ee.

The outer thickness Ee of the filtration medium 4 is less than the maximum thickness Em of said filtration medium in the housing. In order to ensure fluid tightness, the outer thickness Ee of the filtration medium 4 represents between 35% and 55% of the maximum thickness Em of the filtration medium 4, in particular between 40% and 50% of the thickness. In a particular example, the external thickness Ee represents approximately 45% of the maximum thickness Em of the filtration medium 4 in the housing.

The outer projections 16, 17 are arranged to compress the filtration medium 4 to an outer thickness Ee, the outer thickness Ee representing between 80% and 1 10% of the inner thickness Ei. In particular, the outer thickness Ee is less than or equal to the inner thickness Ei of the filtration medium.

The outer thickness Ee is the smallest distance between the first and second outer projections 16,7. In relation to FIG. 5, the external thickness Ee corresponds to the difference between the distance Hm separating the housing elements 2,3 and the sum of the internal heights He1, He2 from the external projections 14,15.

In order to ensure fluid tightness, the outer thickness Ee of the filtration medium 4 represents between 35% and 55% of the maximum thickness Em of the filtration medium 4, in particular between 40% and 50% of the thickness. In a particular example, the external thickness Ee represents approximately 45% of the maximum thickness Em of the filtration medium 4 in the housing.

According to an advantageous form, the outer thickness Ee of the filtration medium 4 is less than or equal to the inner thickness Ei of the filtration medium 4. More advantageously, the outer thickness Ee of the filtration medium 4 is substantially equal to inner thickness Ei of the filter medium, i.e. the compression of the filter medium 4 at the outer projections 16,17 is similar to the compression of the filter medium at the inner projections 14,15.

Thus, if the fluid is not stopped or sufficiently slowed by the first pair of internal projections 14,15, the pair of external projections 16,17 provides a second narrowed passage, sufficient to avoid the circumvention of the filtration medium 4 by the fluid.

This may be the case if, for example, a defect or an irregularity in the filtration medium 4 is at the level of the inner projections 14, 15, preventing the filtration medium from being sufficiently compressed to create a fluid seal.

According to Figures 2 to 5, the first and second outer projections 16,17 are vis-à-vis. The vertices of the outer projections 16, 17 face each other or are slightly offset relative to each other. When they are slightly off, the offset is at most half the width of the outer projections 16,17.

Alternatively (not shown), each housing member 2,3 comprises at least one additional projection forming an additional fluid sealing zone.

Advantageously, for reasons of space, each of the housing elements comprises a single inner projection 14,15 and a single outer projection 16,17.

According to one example, the projections 14, 15, 16, 17 are continuous ribs arranged on the bottom of the housing elements 2, 3. These ribs have in particular a section of triangular, rectangular or oval.

In a particular embodiment, the first and second outer projections 16, 17 have substantially the same dimensions and geometry.

For simplicity of design, the inner 14,15 and outer projections 16,17 exerting substantially the same sealing function, they have substantially identical dimensions and geometry.

For example, in Figures 3 and 4, the inner projections 14,15 and outer 16,17 are formed of continuous ribs. These ribs have a substantially triangular shaped section with a rounded apex.

On the first housing member 2 of this embodiment, the inner projection 14 and the outer projection 16 form, with the bottom and the side wall of the first housing member 2, two distinct grooves. On the second housing member 3, the inner projection 15 and the outer projection 17 form, with the bottom and the side wall of the second first housing member 2, two further distinct grooves. The end of the filtration medium 4 is arranged in the groove outer being thus less compressed than between the pairs of inner projections 14,15 and outer 16,17.

Alternatively shown in Figure 5, the inner projections 14,15 are formed of continuous ribs whose section is triangular rounded apex and the outer projections 16,17 have the shape of a rounded boss attached to the side wall of the housing.

In this type of embodiment, the inner and outer projections 14,16 of the first housing element 2 and the inner and outer projections 1 5,17 of the second housing element 3 each form a single groove. The end of the filtration medium 4 is then compressed between the outer projections 16, 17 to the outer thickness Ee. In connection with the housing members 2,3, these include in particular a first and a second clamping portion 12,13 respectively arranged to maintain tight in the housing said filter medium 4 along its periphery. The clamping portions 12, 13 of the housing elements compress the filter medium so as to reduce the thickness, without being able to provide fluid tightness.

In particular, each of the housing members 2,3 has a cavity formed of a bottom and a side wall, the clamping portions 12,13 being arranged on the bottom of the cavities.

More particularly and as shown in FIGS. 6 and 7, the first and second housing members 2,3 respectively comprise first and second recesses 18, 19 each provided with an outwardly directed peripheral platform forming the first and second clamping portions 12, 13, respectively, arranged to hold tightly in the housing the filtration medium 4 along its periphery. In this configuration, the filtration medium 4 is kept tight between the first and the second platform, which compresses the filtration medium 4 along its periphery. The inner and outer projections 14,15,16,17 are then located on these platforms.

This compression induced by the clamping portions 12, 13 facilitates compression of the filter medium at the inner and outer projections 14,15,16,17. In FIGS. 2 to 5, the housing elements 2, 3 further comprise a side wall extending from the peripheral platform and forming the edge of the housing of the filtration unit 4.

Advantageously, the inner projections 14, 15 are situated at the inner end of the first and second platforms in order to form a marked narrowing of the thickness of the filtration medium 4.

According to a particular embodiment, the bottom of one of the first and second housing members 2,3 comprises a flow deflector formed of a plurality of reliefs 20,21.

In relation to FIGS. 6 and 7, each of the housing elements is provided on its bottom with a plurality of linear reliefs 20, 21 directed obliquely towards the inlet and outlet orifice 8. The side of the compartment At inlet 5, the deflectors help to distribute the flow of fluid to be filtered over the entire surface of the filtration medium 4. At the outlet compartment 6 side, the deflectors help to direct the filtered fluid towards the outlet orifice 8 of the filtration unit 1.

According to a second aspect, the invention relates to a bag system 22 for filtering a fluid, comprising:

a filtration unit 1 according to the first aspect of the invention, and a bag for collecting the filtrate 23, said collection bag 23 being connected, via a first tube 24, to the outlet orifice 8 of the filtration unit 1. To introduce the fluid to be filtered, the bag system 22 further comprises a primary bag 25 containing the fluid to be filtered, said primary bag 25 being connected via a second tubing 26 to the inlet port 7 of the filtration unit 1. This primary bag 25 is either connected to the filtration unit 1 via the second tube 26 or is connected by the user using a perforator-type connector provided at the free end of the tube. the second tubing (not shown). Figure 8 shows more particularly an example of a bag system used to filter the whole blood from a donation and to separate it into plasma and packed red blood cells.

System 22 includes a needle 27 for withdrawing blood from a donor, a primary pocket 25 for collecting whole blood, a filtration unit 1 as previously described for filtering blood leukocytes, a filtrate collection bag. 23, and two satellite bags 28,29 for collecting the plasma and the red blood cells respectively after centrifugation of the filtrate collection bag 23. The pockets 23,25,28,29 and the filtration unit 1 are interconnected by means of flexible tubing and sterilizable.

Claims

1. A filtration unit (1) for filtering a fluid comprising a rigid housing formed of a first housing element (2) and a second housing element (3) between which a filtration medium (4) is arranged to define an inlet compartment (5) for the fluid to be filtered and an outlet compartment (6) for the filtered fluid, said housing having an inlet (7) opening into the inlet compartment ( 5) and an outlet opening (8) opening into the outlet compartment (6), said filter medium having a maximum thickness (Em) in said housing, the first housing element (2) and the second housing element ( 3) respectively comprising first and second inner projections (14,15) extending into the housing, said inner projections (14,15) being arranged to compress the filter medium along its periphery to an inner thickness (Ei ) lower at the maximum thickness (Em) so as to create an internal fluid-tight zone, said filtration unit being characterized in that the first and second housing elements (2, 3) furthermore comprise a first and a second a second outer projection (16,17) extending into the housing, said outer projections being located externally to said inner projections (14,15), said outer projections being arranged to compress the filtration medium (4) to an outer thickness ( Ee) which represents between 80% and 1 10% of the inner thickness (Ei) so as to create an outer sealing zone. 2. Filter unit according to claim 1 characterized in that the outer thickness (Ee) of the filtration medium (4) is less than or equal to the inner thickness (Ei) of the filtration medium (4). 3. Filtration unit according to claim 1 or 2 characterized in that the outer thickness (Ee) of the filtration medium (4) is equal to the inner thickness (Ei) of the filtration medium (4). 4. Filtration unit according to any one of claims 1 to 3 characterized in that the inner thickness (Ei) of the filtration medium (4) is between 35% and 55% of the maximum thickness (Em) of the medium. filtration (4), in particular between 40% and 50% of the maximum thickness (Em) of the filtration medium (4). 5. Filtration unit according to any one of claims 1 to 4 characterized in that the first housing element (2) and the second housing element (3) are sealingly assembled on their periphery. 6. Filter unit according to any one of claims 1 to 5 characterized in that each of the housing elements (2,3) comprises a single inner projection (14,15) and a single outer projection (16, 17). 7. Filtration unit according to any one of claims 1 to 6 characterized in that the vertices of the first and second inner projections (14,15) are facing or are offset by at most half the width of said inner projections (14,15). 8. Filtration unit according to any one of claims 1 to 7 characterized in that the inner projections (14,15) are formed of continuous ribs. 9. Filtration unit according to any one of claims 1 to 8 characterized in that the vertices of the first and second outer projections (16,17) are facing or are offset by at most half the width of said outer projections (16,17). 10. Filter unit according to any one of claims 1 to 9 characterized in that the outer projections (16,17) are formed of continuous ribs. 1 1. Filtration unit according to any one of Claims 1 to 10, characterized in that the inner (14, 15) and / or outer (16, 17) projections have identical dimensions and geometry. 12. Filtration unit according to any one of claims 1 to 1 1 characterized in that the first and second housing element (2,3) respectively comprise a first and a second cavity (18,19) each provided with an outwardly directed peripheral platform forming first and second clamping portions (12,13) respectively arranged to clamp the filter medium (4) tightly around the periphery thereof. 13. Filtration unit according to any one of claims 1 to 12 characterized in that the bottom of the first and second housing element (2,3) comprises a flow deflector formed of a plurality of reliefs (20,21 ). 14. Filtration unit according to any one of claims 1 to 13 characterized in that the outlet orifice (8) comprises a flow restriction (9). 15. Filtration unit according to any one of claims 1 to 14 characterized in that the fluid is a biological fluid such as blood or a blood component. 16. Filtration unit according to any one of claims 1 to 15 characterized in that the filtration medium (4) comprises one or more layers of a nonwoven material. 17. Filtration unit according to any one of claims 1 to 16 characterized in that the filtration medium (4) is a leukocyte removal medium. 18. Bag system (22) for filtering a fluid, characterized in that it comprises: - a filtration unit (1) according to any one of claims 1 to 17, and - a filtrate collection bag (23), said collection bag being connected, via a first pipe (24), to the outlet port (8) of the filtration unit (1). 19. Bag system according to claim 18, characterized in that it further comprises a primary bag (25) containing the fluid to be filtered, said primary bag being connected via a second tubing (26) to the inlet port (7) of the filtration unit (1).