FR2787342A1 - Filter sachet, for use e.g. in biological analysis, has filter dividing inner volume into two compartments with access for pipette in second - Google Patents

Abstract

The sachet comprises two layers of impermeable plastic film joined round their edges to form an open-topped pouch, divided by an inner filter into two compartments. A first compartment is accessible through the top opening, and a second compartment receives the filtrate. The second compartment covers the whole of the bottom of the sachet and has an access channel for a pipette which can be used to extract the filtrate.

Description

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  The present invention relates to a filter bag with a filtrate reserve, usable in particular, but not exclusively, for the preparation of a filtrate from a solid, fibrous, non-homogeneous or insoluble sample, for its microbiological analysis. We know that this type of sample does not allow an analyzable filtrate to be obtained directly: It is usually necessary to add a physiological solution to this sample, shake the solution obtained to wash the sample, then remove the solid sample and, if necessary, dilute the new solution obtained. The liquid phase and the solid phase are then separated

  by sedimentation and / or filtering.

  Many solutions have been proposed to facilitate this separation operation. Thus, one of these solutions consists in using a sachet, of rectangular shape, formed of two sheets of plastic material, secured to one another on three of their sides. The interior volume of the sachet is then divided, transversely, into two compartments by a filtering strip which extends

  longitudinally from the bottom to the opening of the bag.

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  Two pockets are thus obtained, separated from each other by the filter band and which open at the opening of the sachet. One of these pockets is

  intended to contain the sample while the other is used to collect the filtrate.

  To favor the opening of the pocket housing the sample vis-à-vis the filtrate pocket, the filter band is fixed, on the wall of the sachet delimiting the filtrate pocket, at a portion of reduced surface area, at the neighborhood of

the opening of the bag.

  It turns out that this solution, satisfactory in the vast majority of cases,

  nevertheless has a number of drawbacks.

  First of all, when the sachet is placed in a mixer, the filter band is subjected to the mechanical action of the blades of the mixer, and therefore risks deterioration, in addition the solid material of the sample is applied

  energetically against this strip, at the risk of sealing it.

  In addition, this solution practically excludes the possibility of emptying the pocket

  containing the sample without simultaneously draining the filtrate.

  The operation of collecting the filtrate is often difficult because of the difficulty of introducing a sampling instrument into the bottom of the pocket containing this filtrate, especially when the sample contains materials

bulky solids.

  Another drawback of this solution is that it is impossible to separate the two pockets of the bag, for example to keep only the pocket

containing the filtrate.

  The invention therefore more particularly aims to remove all these

disadvantages.

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  It therefore offers, for this purpose, a filter bag comprising two outer plastic sheets secured to one another on a part of their periphery so as to form a pocket open on one side by an orifice, and an element sheet-shaped filter arranged so as to divide the interior volume of the bag into at least two compartments, namely: a first compartment accessible by said orifice and a second

  compartment used to receive the filtrate.

  According to the invention, this filter bag is characterized in that the first compartment is located at a distance from the bottom of the pocket and in that the second compartment occupies at least said entire bottom, means being further provided for allowing the access to a sampling device such as a pipette in this second compartment, this access taking place at the level

of the above orifice.

  Advantageously, this access may be separate from the above orifice.

  Of course, the invention proposes to produce this filter bag according to an industrial process with high production rates, with a material cost.

as low as possible.

  An important advantage of the solution according to the invention is that it allows a large volume of filtrate to be collected more quickly. In fact, filtering is carried out gradually throughout the sample treatment period and not only after it, at the time of sampling, it being understood that during filtering after treatment, the filter tends to get

  clog up due to the presence of solid particles from mixing.

  Embodiments of the invention will be described below, by way of nonlimiting examples, with reference to the appended drawings in which:

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  Figures 1 and 2 show respectively in vertical section and in side view a filter bag according to a first embodiment of the invention; Figures 3 and 4 are schematic vertical sections showing two variants of bags made from a tubular structure; Figures 5 and 6 are perspective representations illustrating the principle of production of filter bags from a flexible plastic tube; Figure 7 is a schematic view illustrating an embodiment of a filtering wall usable in the example of Figure 1; Figures 8 to 10 are cross sections of other embodiments of the filter bag according to the invention; FIG. 11 is a front view of a filter bag comprising a chimney for lateral access to the filtrate tank; Figure 12 is a cross section of the bag shown in Figure 11; Figure 13 is an alternative embodiment in which an upper compartment of the bag can be used to contain a product; Figure 14 is a cross section of a filter bag with a large volume filtrate tank; Figure 15 is a front view of a filter bag with a detachable filtrate tank;

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  Figure 16 is a view of the filtrate reservoir of Figure 15 in the detached state. In the example illustrated in Figures 1 and 2, the filter bag 1 consists of an outer pocket of waterproof plastic 2 and an inner filter pocket 3 of porous material housed in the outer pocket 2. These two pockets 2 , 3 are made from two respective strips folded back on themselves, the flaps being welded to each other laterally, over all

  their length, thanks to two lateral weld lines 4, 5.

  The two pockets 2, 3 here have the same width and open on the same side. The inner pocket 3 has a length less than that of the outer pocket, so that between the bottom 6 of the outer pocket 2 and the bottom 7 of the inner pocket 3 there remains a free volume V serving as a filtrate reservoir. To facilitate access to the sample inside the interior pocket 3, a welding point S is also produced between at least one of the pairs of pads facing the pockets 2, 3, preferably in the vicinity of the orifice

common O of the two pockets 2, 3.

  In this example, access to the filtrate reservoir, for example for pipetting, is effected by the free space between the areas opposite the two pockets 2,3. In the examples shown in Figures 3 to 6, the filter bag is obtained from a tubular element 10 made of a film of impermeable plastic material whose two side edges are connected to each other by a

  longitudinal porous strip 11 which extends over the entire length of the element.

  This tubular element 10 is folded around at least four longitudinal fold lines Li, L2, L3, L4 so that its cross section has the shape of two Vs nested one inside the other and integral with one on the other at their upper edges (fold lines L1, L2). The V shape

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  inner Vl has a height less than that of the outer V shape, so that there remains between their respective bottoms (lines L3, L4) a

  free space E which constitutes the filtrate tank.

  The porous strip 11 then extends in the inner V shape Vl, of

  preferably at the bottom (fold line L4).

  The tubular structure thus folded is then welded from place to place, at the level of transverse welding zones S, and cut along lines of transverse cuts which extend in the middle part of the welding zones S. In the examples represented on Figures 3 and 4, the tubular member 10 is obtained from a waterproof plastic strip whose two lateral edges are connected to each other by means of the porous strip 11. The junction between this porous strip 11 and the waterproof strip can be

  made using two welding lines.

  In the example of FIG. 3, the porous strip 11 is centered on the fold line L4, while in FIG. 4, the strip 11 is arranged on a flap of the

interior V shape.

  On the other hand, in the example of FIGS. 5 and 6, the tubular structure is produced by a plastic tube T which is folded flat to form, in the vicinity of one of the two longitudinal folds, a series of holes constituting a perforated longitudinal strip BP, possibly possibly constituting the filtering element. On this perforated strip BP can then be welded (at two longitudinal weld lines) a strip of material

porous 12 used for filtering.

  The tube thus formed is then folded around the fold lines L'l, L'2,

  L'3, L'4 to obtain a shape whose profile corresponds to that of FIG. 2.

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  Transverse weld lines S are then made from place to place on the folded tube T so as to delimit the filter bags (Figure 6). These sachets are then detached from each other by making cuts at the weld lines S. In these examples, access to the filtrate reservoir (space E) for example for pipetting involves the production of an orifice O located preferably in the upper part of the filter bag, at the junction between the bag

  inside and outside pocket (fold line L2).

  An advantage of the solutions illustrated in FIGS. 3 to 6 consists in that a double-walled bag is obtained in the region where the kneading is carried out. The

  mechanical resistance of this sachet is therefore considerably enhanced.

  As previously mentioned, the invention is not limited to a form

  particular embodiment of the filter.

  Thus, as illustrated in FIG. 7, the filter could be produced from a strip of impermeable plastic material BI comprising, in its central region, an orifice or even a perforated zone, this central region being

  covered by a filter wall PF welded by its edges to the strip BI.

  The advantage of this solution consists in that the filtering wall PF can have dimensions much smaller than that of the strip BI and, consequently, the welding of the strip BI in the bag can be carried out in

  areas of the strip BI not covered by the filtering wall PF.

  This avoids embrittlement of the filter bag due to the presence of the filter wall PF at the outer welds (for example the welds 4, 5

or welding S).

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  In the examples shown in Figures 8 to 10, the filter bag consists of an outer pocket PE of waterproof plastic, the internal volume of which is divided into two compartments by a filter wall PF 'welded to one of the walls of the bag by its two lateral edges and by its lower edge 15, which extends parallel, above the bottom 16 of the bag, the space E 'between the bottom edge 15 and the bottom 16 delimiting inside the bag a volume serving of filtrate tank. Indeed, the compartment CI delimited between the wall P1 of the bag and the filtering wall, which ends in the weld 15, is intended to receive the sample to be analyzed while the compartment C2 delimited between the wall P2 and the filtering wall PF ', who

  ends at the bottom 16, receives the filtrate and therefore plays the role of reservoir zone.

  This compartment C2 is partially closed at the level of the upper orifice OS of the bag thanks to a welding point PS between the wall P2 and the filtering wall PF '. A space is nevertheless left free especially for the passage

  a pipette used to collect the filtrate.

  In the examples shown in FIGS. 8 and 9, the filtering wall PF 'is constituted by a filter which occupies the entire surface of the wall PF'. This filtering wall PF 'ends at the bottom at the level of the weld S in the case of FIG. 9, while in FIG. 8, it extends beyond the weld 15

  to the bottom 16 o it is welded to the two walls Pl. P2.

  In the example illustrated in FIG. 10, the filtering wall is of the type of that illustrated

in figure 7.

  In the examples shown in FIGS. 11 and 12, the interior volume of the bag is divided into two compartments, one upper C3, the other lower C4, by a filter band BF, the longitudinal edges of which extend parallel to the bottom 17 are respectively welded to the two walls of the bag P'l, P'2, while the two transverse edges are welded to the two

  lateral seals of the bag SI, S2.

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  Furthermore, the bag comprises, on one side, an additional lateral weld S3 parallel to the weld S2 which delimits with the two walls

  from the bag a CH chimney used for the passage of a pipette.

  The weld S3 extends to the bottom 17 while the weld S2 is interrupted above the latter so as to obtain communication between the

  lower compartment C4 and the CH chimney.

  The filter bag illustrated in FIG. 13 comprises a filter wall PF "whose lateral edges and the bottom edge are respectively welded to the lateral sides and to the bottom of the bag. However, in this case, the filter wall PF" is also welded to one of the walls P "'l of the bag so as to obtain

  an upper compartment CS opening at the opening O "of the bag.

  This CS compartment allows the insertion of a product contained for example in a small bag. In this example, this upper compartment CS delimits with one of the lateral edges of the bag a chimney CH ′ allowing access, by means of a pipette, to the lower compartment CI delimited below the

  compartment CS between the filtering wall PF "and the wall of the bag P" l.

  The sample of product to be analyzed can be placed in the compartment

  between the bag wall P "2 and the filter wall PF".

  In the examples described above, the lower part of the sachet which constitutes the filtrate reservoir can be initially folded and temporarily fixed against one of the walls of the sachet so that, during kneading, this filtrate reservoir, as well as possibly the filtering wall which delimits it, are not damaged by the mechanical action of the mixer. Once the mixing has been carried out, this lower part of the bag is unfolded

  so that the filtrate can flow into the tank.

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  FIG. 14 shows a reservoir with a structure similar to that of the bag shown in FIG. 9, in which the bottom 16 is kept folded against one of the

  P2 walls of the bag with adhesive or repositionable glue AD.

  The bag shown in Figures 15 and 16 has a structure similar to

that of FIGS. 1 and 2.

  However, in this case, the filtrate reservoir RF is closed by a weld line LS, which extends parallel to the bottom FD, slightly below the filter wall PF, over a length slightly less than the width of the bag, so to leave free a lateral orifice OLl allowing the flow of the filtrate in the RF reservoir. Advantageously, this OLI orifice can be closed off with an external elastic PE clamp coming to apply firmly

  the two walls at the OL1 orifice.

  This gives a tight container in the form of a carton (Figure 16) which can be detached from the rest of the bag by cutting along a line of

  LD cut parallel to the weld line LS1, slightly above it

  this. Furthermore, on the side opposite to the OLI orifice, the weld line LSi can be interrupted to leave free a second orifice OL2 situated at the right of a chimney CH2 delimited by a weld line LS2 which extends parallel to the edge side BL of the bag, from the weld line LS, to the orifice of the bag. This CH2 chimney is intended to allow the filtration of filtrate by pipetting. Of course, the OL2 orifice can be closed in the same way as the OL1 orifice so as to seal the RF filtrate reservoir and allow its detachment in the manner previously mentioned.

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Claims (20)

Claims   1. Filter bag with filtrate reserve comprising two outer plastic sheets secured to one another on a part of their periphery so as to form a pocket open on one side by an orifice, and a filter element in the form sheet arranged so as to divide the interior volume of the pocket into at least two compartments, namely: a first compartment accessible by said orifice and a second compartment serving to receive the filtrate, characterized in that the first compartment is located at a distance from the bottom of the pocket and in that the second compartment occupies at least said entire bottom, means being further provided for allowing access to a sampling device such as a pipette in this second compartment, this   access taking place at the level of the aforesaid orifice.   2. Bag according to claim 1, characterized in that it comprises an external pocket of impermeable material (2) and an internal filtering pocket (3) housed in the external pocket, these   two pockets (2, 3) being made from two bands folded over them-   same, the flaps being welded to each other, laterally over their entire length, by means of two lateral weld lines, the inner pocket (3) having a length shorter than that of the outer pocket so that between the bottom (6 ) of the external pocket (2) and the bottom (7) of the pocket   interior (3), there remains a free volume (V) serving as a filtrate reservoir.   3. Bag according to claim 2, characterized in that a welding point (S) is further produced between at least one of the folding pairs facing the pockets (2, 3), in the vicinity of the orifice common (O) of the two pockets (2, 3). -12- 2787342   4. Bag according to claim 1, characterized in that it is obtained from a tubular element (10) made of a film of impermeable material whose two side edges are connected to each other by a strip longitudinal porous which extends over the entire length of the tubular member. 5. Bag according to claim 4, characterized in that the tubular element (10) is folded around at least four longitudinal fold lines (L1, L4) so that its cross section has the shape of two V nested one inside the other at their upper edges, the inner V shape (V1) having a height less than that of the outer V shape, so that it remains between their respective bottoms (lines L3, L4) a free space (E) which constitutes a filtrate reservoir, the tubular structure thus folded up being welded from place to place at the level of transverse welding zones, and cut out at the level of said zones.   6. Bag according to claim 5, characterized in that the porous strip is centered on the bottom of the inner V-shape or is arranged on one of the two flaps of said inner V-shaped area. 7. Bag according to claim 5, characterized in that the tubular structure is produced by a tube (T) folded flat to form in the vicinity of one of the two longitudinal folds, a series of holes constituting a longitudinal stripe pefforée on which is welded   a strip of porous material (12) used for filtering. - 13- 2787342   8. Bag according to one of claims 4 to 7,   characterized in that it comprises an orifice (O) made in the upper part of the bag, at the junction between the inner pocket and the pocket outside (folding line L2).   9. Bag according to one of the preceding claims,   characterized in that the filter is produced from an impermeable plastic strip (BI) comprising, in its central region, an orifice or a perforated zone, this central region being covered by a filtering wall   (PF) welded by its edges to the strip (BI).   10. Bag according to claim 1, characterized in that it comprises an external pocket (PE) of impermeable plastic material, the internal volume of which is divided into two compartments by a filtering wall (PF ′) welded to one of the walls of the bag by two lateral weld lines and by a lower weld line (15), said lower edge (15) extending parallel, above the bottom (16) of the bag, the space (E ') between the lower border (15) and the bottom   (16) serving as a filtrate tank.   11. Bag according to claim 10, characterized in that the filtering wall (PF ') is connected to one of the two walls of the bag by a welding point (PS) located at the level of the upper orifice (OS) from the sachet.   12. Bag according to one of claims 10 and 11,   characterized in that the filter wall extends beyond the lower weld line (15) to the bottom (16) of the bag where it is welded   to the two walls (Pl, P2) of said bag. -14- 2787342   13. Bag according to claim 1, characterized in that its internal volume of the bag is divided into two compartments, one upper (C3), the other lower (C4), by a filter band (BF) whose longitudinal edges which extend parallel to the bottom (17) are respectively welded to the two walls of the bag (P'l, P'2), while the two transverse edges are welded to the two lateral welds of the bag (Sl, S2).   14. Bag according to claim 13, characterized in that it comprises an additional lateral weld (S3) which delimits with one of the lateral welds (S2) a chimney (CH) opening out.   in the lower compartment (C4.   15. Bag according to claim 1, characterized in that it comprises a filtering wall (PF ") whose lateral edges and the lower edge are respectively welded to the lateral sides and to the bottom of said bag, and in that the filtering wall is further welded to one of the walls (P "l) of the bag so as to obtain an upper compartment (CS) opening at the opening of said bag, this compartment delimiting with one of the lateral edges of the bag a chimney   (CH) opening into the lower compartment (CI) of the bag, located below the upper compartment.   16. Bag according to one of the preceding claims,   characterized in that the lower part of the sachet which constitutes the reservoir for   filtrate is folded and temporarily fixed against one of the walls of the bag.   17. Bag according to one of the preceding claims,   characterized in that the filtrate tank is closed by a weld line which extends parallel to the bottom of the bag, slightly below the filter wall (PF), over a length less than the width of the bag, so as to - 15- 2787342   leave free a side opening (OLI) allowing the filtrate to flow into the tank. 18. Bag according to claim 17, characterized in that the filtrate tank is detachable from the rest of the bag by a cut made parallel to the weld line (LSI), slightly above it.   19. Bag according to one of claims 17 to 18,   characterized in that the aforesaid reservoir is accessible from the orifice of the bag thanks to a chimney (CH2) delimited by two welding lines, this   chimney opening into the tank through a second orifice (OL2).   20. Bag according to one of claims 17 to 19,   characterized in that the aforesaid orifices (OLI and OL2) are closable thanks to elastic pliers.