Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a plate dialyzer with membranes
located between the plates.
Dialyzers have an extensive field of use. They are used
for separating solvent-containing liquids, particularly for separa-
ting colloids from molecularly dispersed smaller substances which
are contained therein. When differently constructed, these plate
dialyzers can also be used for exchange between liquids and gases,
for example, as artificial lungs; for gas exchange, for example,
as artificial gills; or as heat exchangers between two media
capable of flowing, depending upon the selection of the membranes
which separate the media taking part in the material exchange or
heat exchange.
A special field of use for platc dialyzers is that of extra-
corporeal hemodialysis. In that case, the semipermeable mem-
brane takes over the task of the physiological filter of the glomerulus
capillaries. According to the laws of osmosis and diffusion, an
exchange of material then takes place between, on the one hand,
a blood film applied to one side of the membrane and, on the other
hand, a scavenging solution flowing past the other side of the mem-
brane. This use of a plate dialyzer as an artificial kidney is
becoming more and more important at the present time, and for
that reason, hereinafter special reference will be made to a blood
dialyzer. However, the devices of this invention are also intended for
use as blood oxygenators and for other uses not involving blood.
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An ob~ect of the pre~ent invention i8 to eliminate
drawbacks of prior art constructions through the provision of
a plate dialyzer of greatly simplified construction which
provldes improved diffusion characteristics by improving the
flow characteristics of blood and dialysis solution passing
through the device, and providing ease and reliability of
manufacture.
This application is a division of copending Canadian
application Serial No. 190,162 filed January 15, 1974.
The invention as defined in the above-identified parent
application provides, in a diffusion device, a stack of plates
separated by semi-permeable membranes to provide a pair of
separated, isolated flow paths through the diffusion device on
opposite sides of the membranes, the plate having a membrane-
supporting profiled surface comprising a plurality of rows of
upstanding pro~ections, in which the membranes are disposed
across the plates over the pro~ections while stretched in one
direction, the spacing of the centers of the projections in
rows in the general direction of stretching being greater than
the center-to-center spacing of the projections in rows trans-
verse to the general direction of stretching to prevent undue
sagging of the membrane upon wetting in the transverse direction
while permitting lo.w flow resistance across the plates, the
surface also comprising a plurality of support ridges extending
in continuous, uninterrupted fashion across the plate in the
general direction of the flow paths to abut corresponding support
ridges on a~ ad~acent plate of the stack to control tha spacing
between facing plates.
On the other hand the invention of this application
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provides, the method of sealing a diffusion device comprising a
plurality of stacked plates and associated diEfusion membranes
covering a side oE each plate, in which the plates have fluid
flow channels running from end to end thereof adjacent opposed
plate edges, the plate being symmetrical and the channels extend-
ing through opposed plate ends to communicate therethrough which
method comprises: sealing one end of each channel in each stacked
plate, and thereafter encasing the stacked plates and membranes
in a pair of hollow shells which cooperate to enclose the plates,
the shells each defining peripheral flanges which abut one another
in assembled, stack-enclosing position; and thereafter molding
about the outer periphery of the flanges a unitary, integral -:
retention member, and holding the shells and flanges together until
the retention member has hardened, whereby the integral retention
member holds the flanges together in firm, abutting relation.
~ The present invention also may be defined as a diffusion .
device comprising a plurality of stacked plates and associated
diffusion membranes covering a side of each plate; the plates
having fluid flow channels running from end to end thereof adjacent
opposed plate edges; the plates being symmetrical and the channels
extending through opposed plate ends to communicate therethrough;
one end of each channel in each stacked plate being sealed; the
stacked plates and membranes being encased in a pair of hollow
shells which cooperate to enclose the plates; the shells each
defining peripheral flanges which abut one another in assembled,
stack-enclosing position; and a molded unitary integral retention
member positioned about the outer periphery of the flanges, the
integral retention member holding the flanges together in firm,
abutting relation.
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In the drawings, preferred embodiments of this invention
are illustrated. The particular embodiments are improvements on
the dialyzer disclosed in United States Patent ~o. 3,730,350, and
except as otherwise indicated hereln, can be manufactured in
accordance with the teachings of that patent.
Figure 1 is a perspective vlew of a preferred embodiment
of the dialyzer of this invention :in an intermediate state of
manufacture of the casing.
Figure 2 is an enlarged, partial side elevational view,
taken partly in section~ of the dialyzer of Figure 1 after
complete assembly.
Figure 3 is a full side elevational view with portions
broken away of the dialyzer of Figure 1 after complete assembly.
Figure 4 is a diagrammatic view showing the relationship
of 2 plate used in the dialyzer of Figure 1 and its overlying
membrane, and the respective typical flow paths of dialysis
solution and blood.
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~ 5387~
Flgure 5 i8 a plan vlew of a preferred plate design
uaed ln the dialyzer of this lnvention.
Figure 6 is a diagrammatic view of a stack of plates
and associated me~branes.
Figure 7 (appearing on the same sheet of drawings as
Figure 1) is a sectional view taken along line 14-14 of the
stack of plates of Figure 6, with the respective parts slightly
vertically separated for purposes of clarity.
Figure 8 is a partial, greatly enlarged plan view
of one corner of the plate of Figure 5.
Flgure 9 i~ a plan view of anoth&r preferred embodi-
ment of a plate for use in this invention.
Figure 10 is a greatly enlarged perspective view of
a portion of the edge of the plate of Figure 9 and a fragment
of overlying membrane.
Figure 11 is a greatly enlarged plan view of one
corner of the plate of Figure 9.
Figure 12 is a transverse sectional view of another
embodiment of a dialyzer essentially identical to that of
Figure 1, but with a different plate design.
Figure 13 is a dia~rammatic plan view of one corner
of the stack of plates of the device of Figure 12, showing in
phantom how ridges of an ad~oining facing plate sre positioned
wlth resp~ct to the ridges of the plate shown.
Figure 14 is a sectional view taken through the
plates of the device of Figure 12, shawing the relationship
of the membranes and respective ridges of the plates.
Figure 15 (appearing on the same sheet of drawings
as Figure 12) is an enlarged transverse diagrammatic sectional
view showing the shape of the blood manifold in the device of
Figures 1 and 12.
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Plgure 16 (appearlng on the same sheet of d~awings
as Flgure 12) i8 a fragmentary plan view of the ln31de corner
of a shell used to enclo~e the plates ln the de~ice of Flgures
1 and 12.
Flgure 17 (appearlng oll the same sheet of drawlngs
as Flgure 13) i3 an elevatlonal vlew, taken partly ln sectlon,
of a modlfled dialysis of this lnventlon.
~ he stacked plate diffusion device of this applica-
tion is particularly capable of exhibiting a high efficlency
of diffus~on, so that liquid such as blood passed through the
device can be essentially completely processed by a single
pass through the device. This is accomplished because the
device of this invention can be designed with an extremely
thin flow path for blood, since the profiled surface on the
stack of plates may have flow channels which are no more than
0.5 mm. and even less in depth. Also, the dialyzer of this
inventlon can be fabricated in a manner suitable for supporting
ultrathin membranes, which will accelerate the diffuslon
process in a manner unavallable to the designs of the prior
art.
Referring to the diffusion device of Figures l
through 9, a stack of plates and membrances is assembLed in
the manner generally tescribed in U.S. Patent No. 3,730,750,
and then placed between a pair of hollow shells 30, 32 which
may be of molded plastic. Shells 30, 32 face together to
define a chamber inside, the parting line between the t~o
shells being bracketed by a pair of flanges 34, 36.
Prior to insertion of the stack of plates and ~ -
~embranes (portions of which are illustrated in Figure o),
the stack of plates is compressed, desirably at a pressure
of about 14 to 28 kg. per square cm., to cause the facing
rear sldes of the plat~s and the membra=e ends between them
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to become pressed together, to prevent the passage of significant
amount~ of fluid between the facing rear sides. The above pre~sure
values are particularly effective for rectangular plates having a
length of about 12 cm. and a width of about 6 cm., being about 1 mm.
in thickness, and being made of polystyrene plastic with adjoining
ultrathin membranes of about 10 rnicrons thickness. When the above
dimensions are significantly varied, the optimum pressure on the
stack of plates and membranes to achieve the desired effect above
may also change.
The stack typically has been about 100 and 150 separate
plates and overlying membranes.
A relatively thick pressure plate 37 is placed at each end of
the stack of plates, preferably prior to the pressure step, for pro-
tecting and positioning the plates, and to uniformly distribute the
compressive pressure placed on said stack in the pressure step and
thereafter by said casing.
After the pressure step on the stack of plates and membranes,
they are placed inside hollow shells 32, 34, along with spacers 370 and
the shells brought together under pressure so that flanges 34, 36 are
in facing contact with each other as shown in Figure 8. Groove and 0
ring system 35 (Figures 1 and 15) is disposed around manifold chamber
44 and the corresponding outlet manifold chamber, for sealing purposes.
Flanges 34, 36 can then be sealed together by any convel~tional
means. It is preferred to injection mold a frame of plastic 38 (Figures
2 and ~ ~ about the periphery of flanges 34, 36 to enclose the peripheral
portions of the flanges and to permanently bond them together in firm,
abutting relation. Figure 17 al~o shows an identical frame 38 as
applied to a pair of modified shells.
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- Ridgeu 40 arc formed ln sectior~ of flanges 34, 36 to retain
the molded frame 38 in tight-fitting relationship. Another ~et of
ridges (not shown) are typically placed on nange portions 41 on the
other side of the dialyzer.
Typically, blood enters the device of Figure 1 through port 42,
and is distributed by way of manifold chamber 44 (Figure 15) along the
side edge surfaces of the stacked plates and membranes through the
beveled manifold areas 46 (Figure 6) of the plates which function in the
manner of connecting chambers 10, as shown in Figure 3 of U. S.
Patent No. 3, 370, 350. Manifold chamber 44 decreases in depth in all
directions as it radiates from inlet 42, and terminates with a spacer
ridge 50, to position the plates 52. Alternatively, an outer portion of
chamber 44 can be in actual contact with plates 52, with the shells 30, 32
being sufficiently flexible to expand slightly when pressurized as blood
entsrs inlet 42, so that a flow channel having a depth of a few microns
or qo is formed by the pressure. The advantage of this is that the vol~me
of blood contained in the device is brought to an absolute minimum, which
is desirable. Otherwise, the minimum depth of chamber 44 can be about
l mm. or less while in unpressurized condition.
The reduction of the depth of manifold chamber 44 in a manner
dependent on its distance from inlet 42 also assists in the distribution
of blood or other fluid across the sides of plates 52 in a manner which
corresponds to the demand for fluid passing between the plates,
reslllting in improved uniformity of flow with a minimum of blood
volume in the device.
The optimum flow of blood or other fluid through manifold cham-
ber 44 is combined with a minimum blood volume in the manifold cham-
ber when the manifold chamber defines a generally uniforIn curve in all
directions which approximates the following: d--- D 2/ 2~ + C-
10538~7~
d (Figure 15) is the depth of all points of chamber 44 along lines 43
which extend radially from the peripheral wall 45 of fluid port 42 to
meet a line. in perpendicular relation thereto, constituting an extension
of a peripheral edge 47 of chamber 44. do is the depth of the manifold
chamber directly underneath peripheral wall 45 multiplied by the
circumference of port 42; S is the distance of the point measured
along a said perpendicular line 43, measured from wall 45; S0 is the
total distance along line 43 from wall 45 to the peripheral edge 47 of
said manifold; and C is the minimum desired depth of manifold 44 at
peripheral edge 47.
C is preferably about 0. 5 to 1 mm. while, for a dialyzer of the
specific type described herein, d 0 is suitably about 0. S sq. cm., and
S0 about 3 cm. for a dialyzer having about one hundred eighteen 12 cm.
by 6 cm. by 1 mm. plates made of polystyrene plastic and having
adjoining ultrathin membranes of about 10 microns thickness.
Blood from manifold chamber 44 passes between facing rnem-
branes of adjacent plates, and then is collected in a manifold chamber
defined by shell 32, which is similar in structure to chamber 44. The
blood is then conveyed from the device by outlet 54.
Dialysis solution (or oxygen, if the device is intended for use as
a blood oxygenator~ can enter the device by inlet 56, where it enters a
manifold space 60 (Figures 3, 15, and i6) for distribution of the
diabsis solution to the ends of the stack of plates 52. The dialysis
solution then passes into plate inlet ports 62, which constitute a groove
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defined in the back side of each plate which is open to ends 64 of each
plate. Thus dialysis solution passes into the plate stack without
disruption of sealing shoulders 66.
Inlet ports 62 extend through sealing shoulders 66 a distance
sufficient to insure adequate sealing of the ends of the plates. A hole 68
passes entirely through each plate 52 to serve as a connection between
inlet port 62 and flOw channel 70. Channel 70 is a groove inscribed in
the front side of each plate for the distribution of dialysis solution
across one side of the plate.
The dialysis solution then passes from flow channel 70 across
profiled surface 72 to a second fLow channel 74 (Figure 5 ) for collection
of dialysis solution.
The second flow channel then communicates with plate outlet
port means 76, which is typically identical in design and function to inlet
port 62 and hole 68.
As is seen from Figure 5, each plate 52 is symmetrical in its
initial condition, having ports communicating with the exterior at both
ends of flow channels 70 and 74. This simplifies the assembly of the
stack OI plates, since they can be placed together in face-to-face relation
without as much concern about assembly accuracy as is required when -
asymmetrical plates are brought together in face-to-face relation.
After the plates have been assembled in a stack, the respective
second open ends 78 of channels 70, 74 are heat sealed with a hot bar
or otherwise occluded, as at 78a in Figure 2, so that channels 70, 74
are open at only ports 62, 76. This heat sealing step is typically per-
formed after the pressure squeezing step described previously, but
b~fore the stack of plates is placed inside of shells 30, 32.
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1~S3870
Small support plates 79 are placed at each end of plates 52
to preverlt the dialyzate manifold spaces 60 at each end of the plates
fn~m collapsing under the pressures cncountered during the injection
~nolding step which creates frame 38 for s~aling the shells together.
Figure 4 shows schematically the blood flow path 49 running
transversely across plate 52 and separated therefrom by membrane 39,
while the dialyzate flow path 80 is shown to pass into the plate by inlet
port 62 and to move as previously described.
Profiled surface 72 of plate 52 is shown in Figure 8 to con-
stitute rows of upstanding projections 82 which are typically generally
pyramidal structures having a height of 0. 05 to 0. 5 mm.; for example,
0.15 mm. projections 82 cover most of the plate. Preferably, the
alternate rows of projections are laterally shifted with respect to their
adjacent rows, so that both blood and dialysis solution flow in crossing
grooves B3 running between dialysis iluid flow channels 70, 7~, for
improved gentle mixing of both the blood and dialysis fluid as it passes
across the plate face.
The centers of these projections are spaced a distance D1 of
about 0. 3 to 1. 5 mm. apart in the rows which are transverse to the
- 20 general direction of blood flow 81 across the plate ~ace, and generally
parallel to flow channels 70, 74, to provide narrow grooves 83.
The advantage of this is particularly found when ultrathin mem-
brane of no more than about 20 microns thickness is used, in that the
great multitude of tiny and closely spaced projections provides adequate
support for the thin membrane, preventing the membrane from ripping,
or from sagging into the flow channels between the projections, Thus,
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since this plate structure permits an ultrathin membrane to be used,
the diffusion rate between fluid passing on opposite sides of the mem-
brane is substantially improved over the known and conventional
diffusion membranes, which are substantially thicker.
The flow resistance across plates 52 is reduced by spacing
the centers of the projections 82 in rows extending parallel to the blood
nOw direction 81 a greater distance apart than the spacing in the trans-
verse rows described above. This spacing D2 is typically about two to
three times the distance D1, that is, about 0. 5 to 5 mm., preferably
about three times that of D1. A preferred spacing Dl is 0. 5 mm.,
while a preferred spacing D2 is 1. 5 mm. .
Pyramidal projections 82 are typically about 0. 5 mm. long on
their long axis and 0. 2 to 0. 3 mm. long on their short axis as shown
in Figure 15.
It is preferred for the dialysis membrane to be placed across
the plates 52 and projections 82 while stretched in such a direction that
the center-to-center spacing between projections 82 in the stretched
direction of the membrane is greater than the center-to-center
spacing of the projections transverse to the stretched direction of the
membrane. In other words the membrane, which is typically a cellulose-
based membrane for blood dialyzers, is laid across plate 52 while being
gently stretched in a direction generally parallel to direction 81. As
stated above, the projection spacing in a direction perpendicular to
direction 81 is about one-third the distance of the projection spacing
in direction 81.
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1 OS315~7~
Tho Qdvantageof this is that, when wetted, cellulose-based
dialysis membranes and the like tend to expand, and the degree of
expansion in the direction perpendicular to their stretched direction
i8 greater than in their stretched direction. If the degree of expan-
sion of the wetted membrane is too great, it will sag and occlude the
dialyzate flow channels 83 between the projections 82. Thus, pro-
jections 82 are spaced more closely together perpendicular to direc-
tion 81 to account for this increased degree oE sagging of the membrane.
If the membrane is stretched onto the plates in a direction transverse
to direction 81, the spacing of projections 82 can be modified accord-
ingly to prevent undue membrane sagging.
Ridges 84 are positioned to mate with corresponding ridges on
the faces of adjacent plates to serve as spacer members, thus preventing
the projections 82 on facing plates from collapsing between each other
during the squeezing or pressurization step of the stack of plates.
Figure 16 shows a portion of the inside view of shells 30, 32.
Dialyzate inlet tube 56 is shown solvent-sealed in position in an appro-
priate receptacle for the inlet port. Spacer ridge 50 is shown in
position to space the plates in uniform manner.
Referring to Figures 9 through 11, an alternate plate embodi-
ment 85 is disclosed having a profiled surface comprising proJections 86
(Figure ll ). Plate 85 has a pair of sealing shoulders 88 in a manner
similar to the previous plates, but with several dialysis fluid entrance
ports 90, which are grooves defined on the rear side of plate 84 in a
manner similar to that shown in Figure 8 as inlet 62. Holes 92 corres-
pond to holes 68, and four dialyzate channels 94 convey dialysis solution,
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extending transversely to the crossing grooves 87 defined by projec-
tions 86 across plate 85. Channels ~4 are of differing length to pro-
vide uniformly distributed dialysis solution to the space between each
plate and its associated membrane. The arrangement insures that
adequate supplies of dialysis solution are provided to the areas of
plate 84 which are remote from entry ports 90. If desired, projec- `
tions 86 may be spaced in the arrangernent as shown in Figure 8 .
Correspondingly, a plurality of take-up channels 96 are pro-
vided to convey flùid away from the plate by means of holes 98 which ~ ~
communicate with ports 100, defined on the back of plate 85, to permit ~ `
solution to be conveyed to the ex~erior without breaking the seal
provided by sealing shoulder 88.
Tooth-like structures 102 are provided on one side of plate 85
as a means to provide a manifold chamber for blood. The blood is,
as previously described, conveyed across plates 85 between associated
membranes (one of which is shown as membrane 106 in Figure 10) and
correspondingly expelled from the other side of plate 85.
In this embodiment, the plates are stacked so that tooth-like
structures 102 of adjacent facing plates are located at opposite sides
from each other. One set of the teeth 102 then will serve as an inlet
manifold for the blood while the other set on the other plate will serve
as an outlet manifold.
Support ridges 108 function in the same manner as ridges 84
(Figure 5 ) to prevent the projections 86 of plates in face-to-face
relation from being forced together.
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Referring to Figures 12 through 14, a longitudinal sectional
vlew of a device similar to Figure 1 is shown having a modifled plate
design. Blood enters through inlet 42 as before and departs through
outlet 54. Dialysis solution enters through inlet 56 into manifold
chamber 60, which is supported by blocks 7g, as previously shown,
to prevent collapse of manifold chambers 60 during the injection
molding of frame 38. Dialysis solution passes from manifold cham-
ber 60 through a plurality of channels 110 defined on the rear side of
each plate underneath sealing shoulders 112. Channels 110 communi-
cate with holes 114, which pass entirely through each plate just
adjacent the sealing shoulders 112 to provide access from channels
110 to the front side of the plate.
The majority of the plate is provided with alternating rows of
parallel, short ridges 116, typically no more than 0.05 to 0.5 mm.
high, about 1 to 1. 5 mm. long, and substantially less in width (0. 3 mm. ),
in which the ridges of alternating rows define angles to the ridges of
adjacent rows. Preferably, all of the short ridges 116 define acute
angles to the edges of their respective plates between the sealing shoul-
ders 112, and an odd number of rows of short ridges are provided on
lthe plate in at least one, and preferably bath directions, so that the
short ridges 116 of plates disposed in face-to-face relation are in
abutting, angular relation to corresponding ridges 116' of the adjacent
face-to-face plate, to provide spacing and support between the plates.
This i9 illustrated in Figure 14, in which a pair of adjacent membranes
are shown to be retained and held together by crossing ridges 116, 11~'
of adiacent plates. The phantomed ridges 116' of Figure 20 illustrate
the same principle. When crossing ridges 116 are used, the long
ridges 84 ~Figure 5 ) are no longer necessary, and more uniform plate
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support is provided. Dialysis solution is then collected in corres-
ponding collection channels 118 (of identical structure to members
110, 114), which solution is then withdrawn through another
manifold 60 and outlet 57.
In T~'igure 12, ridges 116 ar~ shown enlarged and with fewer
rows than would be customarily used, for purposes of clarity. A
typical ridge spacing 117 between ridges of adjacent rows is about
0.2 mm.
P~eferring now to Figure 17, a modified device of this inven-
lû tion comprising a pair of shells 120, 122 is disclosed. Blood inlet 54
is essentially the same as in Figures 1 and 12, as is blood outlet 42,
frame 38, and an exemplary stack of plates and membranes having
ridges 116 and functioning as described above. However, -the
dialysis solution inlet and outlet have been moved with respect to the
casing of Figures 1 and 12 to avoid the molding problems which result
when the dialysis inlet and outlet are involved with the molding opera-
tion of frame 38. Thus, new dialysis inlet 124 is located below
frame 38, while dialysis solution outlet 126 is located above frame 38.
Dialysis manifold chambers 128 are provided, corresponding to mani-
fold chambcrs 60 in Figures 12 and 15, but having sufficient depth and
volumc to climinate any possiblc nonuniformity of flow caused by the
asymmetric locations of inlet 124 and outlet 126.
It can be seen that shells 120 and 122 can be manufactured
from the same mold, and assembled simply by facing the two shells
in opposite direction during assembly.
The above has been offered for illustrative purposes only, and
is not to be considered to limit the invention, which is defined in the
claims below.
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