Device for the diffusion of substances between two fluids via semipermeable membranes

A device for the diffusion of substances between fluids through semi-permeable membranes is disclosed. The device includes a stack of alternating spacer plates and semi-permeable membranes including transverse passages for each of the fluids so that one of the fluids is conducted on one side of the membranes while the other fluid is conducted across the opposite side of the membranes, and including inlets and outlets for each of the fluids, and in which at least one of the inlets or outlets includes a fluid duct to divert that fluid from its respective transverse passage to a location between the ends of the stack so that it can be fed into or withdrawn from the device in a direction substantially perpendicular to the transverse passages at that location between the ends of the stack.

TECHNICAL FIELD 
The present invention relates to a device for the diffusion of substances 
between two fluids via semipermeable membranes which are arranged in a 
stack separated by spacer plates which comprise through-holes connected to 
inlets and outlets respectively for the respective fluids, a first fluid 
of which is arranged so as to be conducted on one side of the respective 
membranes and a second fluid on the opposite side of the same membranes. 
The device in accordance with the invention is intended foremost to be used 
for the purification of blood, that is to say as a so-called artificial 
kidney. However, it will be clear to those skilled in the art that the 
apparatus in accordance with the invention can also be used for many other 
purposes. It may be used for example for the oxygenation of blood. The 
first of the above-mentioned fluids will then consist of blood, whilst the 
other will consist of oxygen or an oxygen mixture. Alternatively the 
device, in accordance with the invention, may be used for the transfer of 
substances from one gas to another. The term fluid, as used in following 
description, means therefore gas as well as liquid. 
BACKGROUND ART 
Apparatuses of the above-mentioned type are known in themselves and are 
described for example in U.S. Pat. Nos. 3,411,630, 3,501,011, 3,511,381, 
3,516,548, 3,734,298, 3,837,496,, 4,051,041, 4,062,778 and 4,113,625, 
which all show apparatuses comprising a stack of spacer plates with 
membranes, preferably arranged in pairs between them. 
DISCLOSURE OF INVENTION 
The device in accordance with the invention is characterized in that the 
inlet and/or outlet for at least one of the said fluids is connected from 
the side to a duct intersecting the stack and formed by the said 
through-holes. This arrangement provides substantial advantages which will 
be evident from the following description. It is an appreciable advantage 
that the stack in its entirety including clamping elements for the same 
can be made lower than in conventional designs. 
The membranes are preferably arranged in pairs between the spacer plates. 
This makes it possible to conduct the blood without contact with the 
plates between membranes in the individual pairs. It is also possible, 
however, to conceive designs with single membranes arranged between 
adjoining spacer plates. 
The stack of spacer plates and membranes between them is arranged 
appropriately between a top plate and a bottom plate which may then 
include within them the inlet and outlet for the second fluid formed in 
conventional manner. If the last-mentioned inlet and outlet represent 
those requiring less space, the top and bottom plates can be made thinner 
than if they were to contain also the inlet and outlet requiring more 
space. 
The stack of spacer plates and membranes between them can appropriately be 
given an elongated shape with tapering ends. In such a realization the 
inlet and/or outlet connected from the side to the said duct may be formed 
of a connecting nipple which is wholly inside the otherwise largest 
dimensions in lateral or in longitudinal direction of the device. This 
connecting nipple will then require no extra space, whilst being well 
protected at the same time. 
In a preferred embodiment of the subject of the invention, an intermediate 
plate is arranged between the said top plate and the nearest spacer plate. 
This intermediate plate may be provided with an angle nipple which 
contains an angular duct, one end of which is connected to an inlet or an 
outlet and whose other end is connected to the duct intersecting the stack 
and formed by the said through-holes. In this manner an apparatus with a 
small number of seals is achieved. 
A further advantage is obtained if the intermediate plates are patterned in 
substantially the same manner as the spacer plates on the side facing 
them. By imparting such a pattern to two intermediate plate, it becomes 
possible to economize on one spacer plate, so that the device as a whole 
can be made thinner. 
Simple sealing conditions are achieved if the said angular nipple is 
provided with a lateral duct which connects the same directly to the inner 
side of the intermediate plate. 
The stack of spacer plates and membranes between them is preferably gripped 
between the top plate and the bottom plate with the help of clamping rails 
arranged between grooves in the top and bottom plates. At least one of 
these clamping rails is provided appropriately with holes for connecting 
nipples to provide connection to the duct formed by the said 
through-holes. These connecting nipples are appropriately arranged so that 
they are fixed mechanically to the top and bottom plates and/or clamping 
rails, whilst they are liquid-tight against the spacer plates to provide 
connection to the duct formed in these by the said through-holes. 
When two clamping rails arranged on opposite sides of a longitudinal 
apparatus are used, one of these clamping rails is provided appropriately 
with two connection nipples, whilst the other one is not provided with 
any. As a result the connections will be oriented substantially in the 
same direction, which constitutes an advantage in practical use.

BEST MODE OF CARRYING OUT THE INVENTION 
The preferred embodiment shown as an example is intended first and foremost 
to be used as a so-called artificial kidney, that is to say for dialysis. 
It is described therefore in the following with reference to such a 
treatment. 
As is evident most clearly from FIGS. 3 and 4, the device shown comprises a 
stack of spacer plates 1 with membranes 2 arranged in pairs between them. 
This stack is arranged between a bottom plate 3 and a top plate 4. Inside 
the last-named are situated a lower intermediate plate 5 and an upper 
intermediate plate 6. 
The bottom plate 3 and the top plate 4 are held firmly clamped against the 
stack located between them with the help of clamping rails 7. The dialysis 
liquid is supplied and withdrawn via identical connecting nipples 8 fixed 
into holes in one of the clamping rails 7. In the same manner 
substantially identical inlets and outlets 9 for the blood are provided in 
the top and bottom plates. If the connection 9 shown in FIG. 1 constitutes 
the inlet for the blood, a corresponding outlet (not shown) will thus be 
found on the opposite end of the bottom plate 3. 
The apparatus as a whole has an elongated shape with tapering ends. The 
advantages of such a realization are demonstrated in greater detail in 
U.S. Pat. Nos. 4,062,778 and 4,113,625, the disclosures of which are 
incorporated herein by reference thereto. 
The connection 8 for dialysis liquid is shown on a larger scale in FIG. 3 
connected to an angle nipple 10 on the lower intermediate plate 5. This 
angle nipple contains an angular duct 11 which is connected with one end 
to a duct 12 formed by holes 13 in the spacer plates 1 and which runs 
transversely through the stack of spacer plates 1 and membranes 2. From 
the holes 13 the dialysis liquid flows through ducts 14 on the one side of 
the spacer plates, through through-holes 15 in the spacer plates and 
through ducts 16 on the opposite side of the spacer plates. Thanks to 
through-holes 17, the dialysis liquid is finally distributed to ducts 18 
on the working surface proper of the spacer plates. 
Numeral 8a designates a seal between the angle nipple 10 and the connecting 
nipple 8 which otherwise is fixed mechanically in the bottom plate 3. 
In the example shown, the upper side of the lower intermediate plate 5 and 
the lower side of the upper intermediate plate 6 have been provided with a 
pattern substantially corresponding to that on the spacer plates. For 
conducting the dialysis liquid to the upper or inner side of the lower 
intermediate plate 5, a special lateral duct 19 exists which directly 
connects the angle duct 11 to the ducts 27 on the inside of the 
intermediate plate 5. 
The duct 12 penetrating through the stack is shut off at the end opposite 
the angle nipple 10 by a closing plug 21. 
A blood outlet or blood inlet 9 is shown on a larger scale in FIG. 4. Here 
the blood is distributed through a duct 22, which is formed by holes 23 in 
the spacer plates 1 and by blood buttons 24 shown schematically. The 
latter, which are arranged between the membranes arranged in pairs, may be 
of the design, for example, which is described in U.S. Pat. No. 3,837,496, 
the disclosure which is incorporated herein by reference thereto. At the 
bottom the duct 22 is shut off by means of a plug 25. The blood is then 
conducted, as can best be seen from FIG. 6, between the membranes 2 along 
the ducts 20, and is then distributed on the working surface proper by 
virtue of the V-shaped duct system 28. 
In FIGS. 5-11 the lower intermediate plate 5 is shown in greater detail. 
Since the upper intermediate plate 6 by and large corresponds to the lower 
one, there is no need to show or describe it too in greater detail. The 
spacer plates may be designed substantially in accordance with the upper 
side of the intermediate plate 5 shown, that is to say largely in 
accordance with FIGS. 6 and 11. There is no need here either, therefore, 
for a detailed description. 
The angle nipple 10 with angle duct 11 and lateral duct 19 can best be seen 
in FIGS. 7 and 8. As is evident from these figures, the angle duct 11 is 
partly divided into two ducts by an inner partition 26. The lateral duct 
19 ends in a duct system 27, which can also be seen in FIG. 6, surrounding 
the one end of the angle duct 11, and in FIG. 3. From the duct system 27 
the dialysis liquid issues into a V-shaped duct system 28 and via this 
into the ducts 18 in the working surface proper of the upper surface of 
the intermediate plate 5. In the same manner the dialysis liquid issues 
into corresponding ducts 18 in the spacer plates 1 designed substantially 
in the same manner. 
In FIG. 5 is shown the lower intermediate plate 5 seen from underneath. On 
the left-hand side in the figure an angle nipple 10 and a blood connection 
9 can be discerned. The latter corresponds by and large to the connection 
9 shown in FIG. 4 seen from above. 
On the right-hand side in FIG. 5, end closures for the ducts 12 or 23 can 
be seen. They are designated here by numerals 10' and 9' respectively. In 
the duct closure 10' through-openings 29, 30 and 31 are present, which can 
also be seen in FIG. 3. The duct closure 9' comprises an oval hole 32 and 
this can also be seen in FIG. 4 inside the plug 25. 
The hole 32 is also evident in FIG. 10, where the through-openings 29, 30 
and 31 are also noticeable. 
Numeral 33 generally designates sealing beads, adapted so as to press 
together in a tight manner the membranes arranged in pairs, in order to 
prevent blood and dialysis liquid from becoming mixed. At the same time 
they seal the apparatus towards the outside. 
Other details shown on the drawings should be fairly self-explanatory to 
those skilled in the art, or they are of minor importance in respect of 
the invention and do not, therefore, require detailed description. 
Naturally, the invention is not limited exclusively to the embodiment 
described above, but may be varied within the scope of the following 
claims. For example, the apparatus shown may be combined with one or more 
details from the aforementioned patents, which, together with the present 
application, describe a series of apparatuses which can be said to form a 
joint chain of development.