U.S. patent application number 10/982451 was filed with the patent office on 2005-06-02 for filtering device with associated sealing design and method.
Invention is credited to Brown, William Kelly, McGhee, Troy, Petersen, Danen Lee, Pope, Rodney William, Stroup, Eric Wilson, Tuominen, Olli.
Application Number | 20050115885 10/982451 |
Document ID | / |
Family ID | 21726656 |
Filed Date | 2005-06-02 |
United States Patent
Application |
20050115885 |
Kind Code |
A1 |
Pope, Rodney William ; et
al. |
June 2, 2005 |
Filtering device with associated sealing design and method
Abstract
A filter device made of less expensive material than comparable
filter devices heretofore has basic filter components plus some
unique design aspects and an additional ring component. The ring
provides an interface inside the filter which enables the potting
compound to adhere to the filter and create a seal between a first
and second fluid compartment within the filter. An embedded region
of the ring possesses a detailed geometry which helps ensure that a
delamination would be localized and unable to propagate from the
first to the second compartment, maintaining the structural
integrity of the filter device. To ensure that the sealing
interface remains intact and free from delamination, the ring is
subjected to a surface treatment, which modifies the surface energy
of the ring. This modified surface energy of the ring allows the
hydrophilic potting compound to more effectively bond to the
modified hydrophobic ring.
Inventors: |
Pope, Rodney William;
(Clearfield, UT) ; Stroup, Eric Wilson; (North
Ogden, UT) ; Brown, William Kelly; (South Weber,
UT) ; Petersen, Danen Lee; (E. Ogden, UT) ;
Tuominen, Olli; (Marlboro, MA) ; McGhee, Troy;
(North Ogden, UT) |
Correspondence
Address: |
Gibson, Dunn & Crutcher LLP
Attn: Docketing Department
Suite 4200
1801 California Street
Denver
CO
80202
US
|
Family ID: |
21726656 |
Appl. No.: |
10/982451 |
Filed: |
November 4, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10982451 |
Nov 4, 2004 |
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10007516 |
Dec 5, 2001 |
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6830685 |
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Current U.S.
Class: |
210/321.88 ;
210/445; 210/450; 210/451; 210/453; 210/500.23 |
Current CPC
Class: |
B01D 63/02 20130101;
B01D 63/022 20130101 |
Class at
Publication: |
210/321.88 ;
210/445; 210/450; 210/451; 210/453; 210/500.23 |
International
Class: |
B01D 063/02 |
Claims
1-61. (canceled)
62. A filter device comprising: a housing having a first end; a
first ring joinable to said first end wherein said first ring has a
first annular anchor on an interior portion of said first ring; a
first flange cap joinable to said first ring forming a first seal,
wherein said first flange cap is separated from contact with said
first end of said housing by said first ring; a plurality of
microfibers extending from said first ring through said housing;
and a first potting material encasing said plurality of microfibers
at said first ring, encasing said first annular anchor, and
contacting a portion of said first flange cap forming a second
seal; wherein said first seal prevents a first fluid introduced
into the filter device from escaping to an exterior of the filter
device, and said second seal prevents said first fluid from
contacting a second fluid introduced into the filter device.
63. The filter device according to claim 62 further comprising: a
first plurality of rounded ridges on an upper surface of said first
annular anchor and a second plurality of rounded ridges on a lower
surface of said first annular anchor.
64. The filter device according to claim 63 further comprising: a
first plurality of radial channels perpendicular to said first
plurality of rounded ridges on said upper surface of said first
annular anchor; wherein said first plurality of radial channels
allow air to escape when said first potting material is applied to
the filter device.
65. The filter device according to claim 63 wherein said first
annular anchor receives a surface treatment, wherein said surface
treatment modifies a surface energy of said first and second
plurality of rounded ridges on said first annular anchor, and
further wherein said first and second plurality of rounded ridges
increases a surface area of said first annular anchor treatable
through said surface treatment.
66. The filter device according to claim 62 further comprising: a
second end of said housing opposite said first end; a second ring
joinable to said second end wherein said second ring has a second
annular anchor on an interior portion of said second ring; a second
flange cap joinable to said second ring forming a third seal,
wherein said second flange cap is separated from contact with said
second end of said housing by said second ring; and a second
potting material encasing said plurality of microfibers at said
second ring, encasing said second annular anchor, and contacting a
portion of said second flange cap forming a fourth seal; wherein
said third seal prevents said first fluid introduced into the
filter device from escaping to said exterior of the filter device,
and said fourth seal prevents said first fluid from contacting said
second fluid introduced into the filter device.
67. The filter device according to claim 66 further comprising: a
third plurality of rounded ridges on an upper surface of said
second annular anchor and a fourth plurality of rounded ridges on a
lower surface of said second annular anchor.
68. The filter device according to claim 67 further comprising: a
second plurality of radial channels perpendicular to said third
plurality of rounded ridges on said upper surface of said second
annular anchor; wherein said second plurality of radial channels
allow air to escape when said second potting material is applied to
the filter device.
69. The filter device according to claim 67 wherein said second
annular anchor receives a surface treatment, wherein said surface
treatment modifies a surface energy of said third and fourth
plurality of rounded ridges on said second annular anchor, and
further wherein said third and fourth plurality of rounded ridges
increases a surface area of said second annular anchor treatable
through said surface treatment.
70. The filter device according to claim 66 further comprising: a
first fluid inlet port through said first flange cap; a first fluid
outlet port through said second flange cap, wherein a first fluid
pathway is defined by said first fluid inlet port, said plurality
of microfibers, and said first fluid outlet port; a second fluid
inlet port through said housing and proximate to said first end;
and a second fluid outlet port through said housing and proximate
to said second end, wherein a second fluid pathway is defined by
said second fluid inlet port, a space between said plurality of
microfibers, and said second fluid outlet port.
71. The filter device according to claim 66 wherein said first ring
is spin welded to said first end, said second ring is spin welded
to said second end, said first flange cap is spin welded to said
first ring, and said second flange cap is spin welded to said
second ring.
72. The filter device according to claim 71 further comprising: a
first plurality of nubs on an outer portion of said first ring; and
a second plurality of nubs on an outer portion of said second ring;
wherein said fist and second plurality of nubs assist in said spin
welding.
73. The filter device according to claim 71 further comprising: at
least one annular channel located between said first ring and said
first end; and at least one annular channel located between said
second ring and said second end; wherein each of said at least one
annular channel accommodates a flow of flash material during said
spin welding.
74. The filter device according to claim 71 further comprising: at
least one annular channel located between said first ring and said
first flange cap; and at least one annular channel located between
said second ring and said second flange cap; wherein each of said
at least one annular channel accommodates a flow of flash material
during said spin welding.
75. The filter device according to claim 66 wherein said first ring
is laser welded to said first end, said second ring is laser welded
to said second end, said first flange cap is laser welded to said
first ring, and said second flange cap is laser welded to said
second ring.
76. The filter device according to claim 62 wherein each of said
plurality of microfibers are hollow and semipermeable.
77. The filter device according to claim 62 wherein said housing is
cylindrical in shape.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of Application Ser. No.
10/007,516, filed on Dec. 5, 2001, titled "Filtering Device With
Associated Sealing Design And Method", now U.S. Pat. No. ______,
which is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
[0002] This invention relates to the field of filtering devices,
and more particularly, to a hollow fiber type filter device having
a single use or disposable design together with a method for using
and manufacturing the same.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1 shows an overall side view of an embodiment of the
filter device of the present invention.
[0004] FIG. 2 shows an exploded isometric view of the filter device
of FIG. 1 in an embodiment of the present invention.
[0005] FIGS. 3A-3D show various views of the ring of FIGS. 1 and 2
of an embodiment of the filter device of the present invention.
[0006] FIG. 4 shows a cross-section view of a portion of the filter
device of FIG. 1 in an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0007] Referring to the Figures, in which like numerals refer to
like portions thereof, FIG. 1 shows an overall side view and FIG. 2
shows an exploded isometric view of an embodiment of the filter
device of the present invention. Referring now to FIGS. 1 and 2,
Filter Device 100 in this embodiment of the invention is a dialyzer
used for hemodialysis. One skilled in the art will recognize that
the filter device of the present invention could also be used for
filtering other types of fluids besides blood, including, but not
limited to water, sewage, or other types of chemical
separation.
[0008] Filter Device 100 is a dialyzer utilized by patients with
kidney disease who suffer from the adverse effects of toxin
build-up in their blood. Dialysis is a process which employs an
artificial kidney to remove those toxins. In hemodialysis a
dialyzer is used which contains a semipermeable membrane dividing
the dialyzer into two compartments. Blood is pumped through one
compartment and a dialysate solution through the second. As the
blood flows by the dialysis fluid, separated by the semipermeable
membrane, blood impurities such as urea and creatinine diffuse
through the semipermeable membrane into the dialysis solution by
diffusion, convection, and absorption. The electrolyte
concentration of the dialysis fluid is set so as to maintain
electrolytic balance within the patient.
[0009] Dialyzers are known in a variety of configurations. The
basic concept is to maximize the surface area of the membrane
dividing the blood side from the dialysate side, so that the
pressure gradient diffusing toxins from the blood side into the
dialysate side and diffusing nutrients or pharmacological agents
from the dialysate side into the blood side can operate over a wide
area. On the other hand, there are size constraints to the overall
three dimensional volume of the device, in order to fit into the
hemodialysis apparatus.
[0010] Filter Device 100 has a large number of Microfibers 104 (not
shown in FIG. 2) encased in a Housing 102, which is a hollow
cylinder open at both ends. In other designs, Housing 102 may be
open only at one end, and Microfibers 104 are looped in a U-shape
in Housing 102 such that both open ends of each microfiber are
located at the one open end of Housing 102 (not shown). In either
design, thousands of the hollow semipermeable Microfibers 104 carry
blood in a pathway through one set of open ends of each Microfiber
104, through the interior of each Microfiber 104, and exiting out
of the other open end of each Microfiber 104.
[0011] As shown in FIG. 1, thousands of the hollow semipermeable
Microfibers 104 carry blood in a pathway that enters from one end
through a first Blood Inlet/Outlet Port 118 to the opposite end and
out through a second Blood Inlet/Outlet Port 118 so that blood
flows through the interior of each Microfiber 104 in a first
direction. Dialysate Inlet/Outlet Ports 110 are also present on
opposite ends of Housing 102. A first Dialysate Inlet/Outlet Port
110 carries dialysate in a pathway into Housing 102, the dialysate
flows through Housing 102 in a countercurrent direction to the
blood flow and in the space between each Microfiber 104, and a
second Dialysate Inlet/Outlet Port 110 carries the dialysate out of
Housing 102. The material exchange thus takes place across the
semipermeable membrane that is the walls of each Microfiber 104.
Label 114 is preprinted and applied after assembly. A Cap 112
screws into each Blood Inlet/Outlet Port 118 after sterilization,
and is utilized to ensure an uncontaminated fluid pathway and is
typically not removed until the technician is ready to connect the
blood lines.
[0012] The design of Filter Device 100 produces a high surface area
for material exchange in a relatively low volume device. For
example, a Filter Device 100 having a 6.3 cm cylindrical diameter
and a 25.4 cm length can easily accommodate a bundle of about
12,000 to 13,000 Microfibers 104. If each Microfiber 104 has a 0.60
cm circumference and is 24 cm long, the total surface area of all
12,000-13,000 Microfibers 104 is approximately 180 cm.sup.2.
[0013] The manufacture of Filter Device 100 begins by joining Rings
108 into each end of Housing 102. Each Ring 108 is then joined to
Housing 102. Many different joining techniques may be employed
including, but not limited to, spin (friction) welding, laser
welding, ultrasonic welding, high frequency welding, gluing,
adhesive bonding, solvent bonding, screwing with threads, snap
fitting, or any other suitable plastic joining technique. In this
embodiment of the invention, spin welding is utilized. A plurality
of Nubs 120 spaced apart on the outer surface of Ring 108
constitute the spin welding drive features to assist in the spin
welding process. Next, open-ended Housing 102 is filled with a
bundle of Microfibers 104 which extend in the longitudinal
direction throughout the length of Housing 102 and extending a
short distance beyond each end. A Potting Cap 202 (FIG. 2) is
attached to each Ring 108 to close off each end of Housing 102.
Housing 102 is then positioned in a centrifuge to allow rotation
about an axis perpendicular to the central longitudinal axis,
wherein the axis of rotation extends through the midpoint of
Housing 102. Potting Compound 116 is then injected into Dialysate
Inlet/Outlet Ports 110 on each end of Housing 102, is spun in a
centrifuge, and the fibers are effectively potted in the dialyzer.
Alternatively, each end of Housing 102 may be separately spin
welded and injected in a two step process. In one embodiment of the
invention, polyurethane is used for Potting Compound 116. Epoxy or
any other suitable compound may also be used as a potting material.
The centrifugal force produced by the rotation in the centrifuge
forces Potting Compound 116 to each end, where it sets and
hardens.
[0014] Housing 102 is then removed from the centrifuge, and each
Potting Cap 202 is removed from each end to expose the hardened
Potting Compound 116 encasing the ends of each Microfiber 104.
Potting Compound 116 and the encased Microfibers 104 at each end
are then cut through in a plane perpendicular to the central
longitudinal axis of Housing 102, and the Microfibers 104
longitudinal axes, to expose the interior channels of each
Microfiber 104. The result is that the ends of each Microfiber 104
are open for blood flow through the interior channels of each
Microfiber 104 extending through Housing 102, but the rest of the
space surrounding each Microfiber 104 at both ends of Housing 102
is filled with polyurethane, creating a seal between the blood and
dialysate.
[0015] After the potting and cutting process, a Flange Cap 106 is
attached to each Ring 108 and spin welded together, permanently
adhering it to Filter Device 100. This design eliminates an O-ring
typically used to assist in the sealing of the blood compartment of
a dialyzer.
[0016] Dialysate Inlet/Outlet Port 110 in the walls of Housing 102,
which are toward but not at the very ends, remain open for
dialysate flow there through. A dialysate line is connected to one
Dialysate Inlet/Outlet Port 110 and a dialysate return line is
connected to the other Dialysate Inlet/Outlet Port 110. The
dialysate thus flows through the interior of Housing 102 in the
space surrounding the Microfibers 104 in one direction. Blood flows
from an arterial blood line from a patient connected to a first
Blood Inlet/Outlet Port 118, entering the exposed ends of each
Microfiber 104 and flowing through the interior channels through
the length of Housing 102 in a countercurrent direction, and then
out of the other exposed ends of each Microfiber 104 and back to
the patient through a venous blood line connected to a second Blood
Inlet/Outlet Port 118. The blood is thus separated from the
dialysate by the semipermeable membranes of the microfiber walls,
which allow the transfer of liquids, toxins, and nutrients by
solute diffusion and pressure gradients.
[0017] Typically, dialyzers are reused. After use in a hemodialysis
session for a patient, the dialyzer is cleaned and sterilized for
subsequent use by the same patient for a next hemodialysis session.
The cleansing, sterilizing, storing, and cataloging of each
dialyzer to ensure safe use by the same patient is an expensive and
laborious task, and fraught with risk should the dialyzer not
effectively have had all of the sterilizing chemicals removed from
the dialyzer and the patient be exposed to the sterilizing agent
itself. Additionally, if the sterilization process was not able to
effectively sterilize the dialyzer, the patient may be subjected to
a "non` biocompatible medical device. Further logistic risk remain
in the case the dialyzers get mixed up and the wrong dialyzer is
used with the wrong patient. Heretofore, single use dialyzers have
been too expensive to manufacture to be very practicable. To
accommodate the growing demands of the hemodialysis market for
single use or disposable dialyzers, the design of Filter Device 100
of the present invention has solved the high cost problem
associated with the current manufacture of disposable dialyzers,
but yet maintain the performance and medical requirements necessary
for successful hemodialysis.
[0018] Various seals in a dialyzer must remain intact, which is of
special concern when replacing the currently proven expensive
materials, from which many dialyzers are made, with less expensive
materials in order to reduce costs. Any dialyzer inherently has at
least two sealing regions in its respective design. First, the
blood and dialysate compartments must be sealed from each other to
ensure that a blood leak does not occur. The second seal consists
of sealing either the blood or dialysate compartment from the
exterior of the dialyzer.
[0019] In nearly all dialyzers currently marketed throughout the
world, polyurethane is used as a potting material to seal to the
housing to ensure that the blood and dialysate compartments are
sealed from each other. An O-ring is typically used to separate the
blood from the exterior of the dialyzer.
[0020] The seals in a dialyzer must not only maintain their
integrity through a specified shelf life duration and during the
dialysis treatment process, but must also maintain their integrity
during the manufacturing process.
[0021] The Filter Device 100 of the present invention utilizes
molded parts, including Housing 102 and Flange Caps 106, made with
a polypropylene homopolymer that possess comparable general
characteristics to the polycarbonate used in the molded components
of the Fresenius Hemoflow series of dialyzers, but is considerably
less expensive. The choice of materials for the dialyzer are
heavily dependent upon the manufacturing processes employed. Though
the optical property of the polypropylene homopolymer is
significantly more "hazy" compared to polycarbonate, the blood and
dialysate compartments are still readily visible to
technicians.
[0022] Polyurethane in one embodiment of the invention is used as
Potting Compound 116 for Filter Device 100. Instead of an O-ring, a
separate Ring 108 molded from polypropylene is utilized. One Ring
108 is spin welded into each end of Housing 102. Flange Caps 106
are then spin welded onto Rings 108 after Filter Device 100 has
been potted and cut. Other joining techniques as listed above,
including laser welding, may be used instead of spin welding.
However, spin welding is based on a very simple concept and the
process generally can be performed faster, less expensively, and
with much less continuous maintenance and re-alignment as compared
to laser welding. The weld joint designs utilized in Filter Device
100 are very robust and conducive to the rigors of large scale
manufacturing.
[0023] During the potting process, the interior portion of each
Ring 108 becomes encased in Potting Compound 116. This creates the
first seal between the blood and the dialysate compartments. After
potting, the potting caps are removed, the ends are cut, and Flange
Caps 106 are spin weld onto Rings 108. The spin welded region
constitutes the second seal region, which seals the blood
compartment from the outside of Filter Device 100 (a seal which has
typically utilized an O-ring). Filter Device 100 is then
conditioned during a low flux conditioning process, and then
sterilized. Sterilization may be accomplished in a variety of ways,
including ethylene oxide (EtO), steam, or radiation
sterilization.
[0024] A disadvantage of polypropylene is that its hydrophobic
property has a tendency to delaminate from the hydrophilic
polyurethane potting material due to the chemistry of surface
adhesion between the two materials, resulting in leaks between the
blood and dialysate compartments. A two-pronged approach has been
taken to solve this delamination problem associated with the use of
polypropylene. The first involves building a detailed geometry into
the design of Ring 108 to minimize delamination or propagation of
the delamination through the creation of physical stops, discussed
more fully in relation to FIGS. 3A-3D. The second involves the
modification of the surface characteristics of the polypropylene to
increase adhesion between it and the polyurethane, also discussed
more fully in relation to FIGS. 3A-3D.
[0025] FIGS. 3A-3D show various views of an embodiment of the ring
of FIGS. 1 and 2 in an embodiment of the single use dialyzer of the
present invention. FIG. 3A shows a front view of Ring 108. FIG. 3B
shows a side view of Ring 108. FIG. 3C shows an isometric
cross-sectional view of a portion of Ring 108 as seen along lines
B-B of FIG. 3A. FIG. 3D shows a cross-sectional view of Ring 108 as
seen along line A-A of FIG. 3A.
[0026] Referring now to FIGS. 3A-3D, Ring 108 is shaped to coincide
with Housing 102 and Flange Caps 106 that each Ring 108 is mated
with. Typically, Housing 102, Flange Caps 106, and Rings 108 are
circular, but other shapes may also be utilized. Ring 108 has
Annular Tongue 316 which fits into an annular groove in Housing 102
formed by Annular Inner Lip 410 and Annular Outer Lip 412 in an
interference based snap fit fashion in one embodiment of the
invention (see FIG. 4). Ring 108 also has Annular Outer Rim 312 and
Annular Inner Rim 314 which form an annular groove which is
designed to receive Flange Cap 106 in an interference based snap
fit (see FIG. 4). Potting Cap 202 used in the manufacturing process
(FIG. 2) is also designed to fit into this annular groove.
[0027] Several methods are available to treat the surface of Ring
108 to modify its surface energy to increase adhesion between it
and the polyurethane, including plasma, corona discharge, and flame
treatments. By increasing the ability of the surface of Ring 108 to
adhere to the polyurethane, Ring 108 has been shown to be effective
in eliminating potential issues regarding delamination. A
delamination could potentially allow the two fluid pathways to mix
outside of the filtering microfibers. The detailed geometry of the
design of Ring 108 increases the surface area treatable through
surface treatment, enhancing the effects of modifying the surface
energy of Ring 108.
[0028] In one embodiment of the invention, a typical surface
treatment process which allows for the most practical integration
into a clean room automated assembly process is the "corona
discharge" surface treatment technique. This treatment method is
currently utilized in industry to increase the adhesion of inks,
coatings, and adhesives to polyolefins, such as polypropylene. The
corona discharge consists of a high voltage electrical discharge
that is created between two electrodes across a specified distance.
This discharge ionizes the gases present between the electrodes and
creates unstable chemical species (mainly free radicals), which
possess sufficient energy to initiate bond cleavage at the polymer
surface. A small fan is situated just above the corona discharge
heads and blows the reactive chemical species onto the polymeric
surface of the part being treated, Ring 108, as shown by arrows 308
in FIG. 3D. Ring 108 is especially well suited to accommodate the
corona discharge treatment process, presenting a large surface area
due to its geometric design. The corona discharge treatment process
is based on the surface being treated to be directly exposed to the
electrical discharge, and sections of the surface that are not
directly in the "line of sight" of the discharge do not receive as
effective treatment. Ring 108 is designed to ensure that the
polyurethane interface regions of the ring receive optimal amounts
of the surface treatment, while also forcing any delamination that
may occur to follow a very difficult pathway. Annular Rounded
Ridges 318 on the upper and lower surfaces of Annular Anchor 306
have relatively sharp transitions between them to ensure that
optimal amounts of "treatable" area of Ring 108 are exposed to the
corona discharge treatment process. When this entire section of
Ring 108 is embedded in the Potting Compound 116, delamination is
forced to essentially "start" again and again after being initiated
anywhere along the Ring 108/Potting Compound 116 interface as shown
in a close up cross-section of Ring 108, Housing 102, and Flange
Cap 106 shown in FIG. 4. The effects of the corona discharge
treatment may also be somewhat distributed onto Annular Rounded
Ridges 318 in the lower surface of Annular Anchor 306 as the
unreacted unstable chemical species will be blown into the center
of Ring 108 and react with the lower surface of Ring 108, which
also is embedded in Potting Compound 116. The thickness of Annular
Anchor 306 tends to decrease or taper inwardly from Annular Outer
Rim 312, as opposed to increasing or expanding inwardly, which aids
in this surface treatment process.
[0029] Covalent bonds are produced on the surface of the polymer as
the surface is oxidized during the treatment process. This
oxidative coating on the polypropylene surface allows the
hydrophilic polyurethane to effectively bond to the modified
polypropylene. Because the oxidative coating on the polypropylene
has the ability to interact with the oxygen present in the air, and
simply the dynamic nature of polymers, the stability of the corona
discharge treatment is limited to a specified amount of time.
However, once potted, the modified surface of Ring 108 is permanent
and does not degrade over time.
[0030] A large portion of Ring 108, Annular Anchor 306, serves as a
mechanical lock and is located at an interior portion of Ring 108
and is completely embedded in Potting Compound 116. This portion of
Ring 108 forces delamination to completely circumvent around and
through the Annular Rounded Ridges 318 to create an actual
delamination between the blood and dialysate compartments of Filter
Device 100 as shown in FIG. 4.
[0031] Another feature of Ring 108 are Radial Channels 302. As the
polyurethane potting mass "backfills" from the ends of Filter
Device 100, the residual air from the ends of Filter Device 100
becomes entrapped due to Annular Rounded Ridges 318 of Annular
Anchor 306 portion of the design of Ring 108. Not allowing the
potting mass to bind to the corona discharge treated surface
because of an air pocket could potentially create an initiation
site for a delamination. To address this situation, Radial Channels
302 are periodically notched perpendicular to Annular Rounded
Ridges 318 of the upper surface of Annular Anchor 306 of Ring 108,
which allows the air to escape and not become trapped during
"backfilling" of Potting Compound 116. The upper surface of each
Annular Anchor 306 is that surface which faces outward toward the
ends of Housing 102.
[0032] FIG. 4 shows a cross-section view of a portion of the single
use dialyzer of FIGS. 1 and 2 in an embodiment of the present
invention. Referring now to FIG. 4, Dialysate Compartment 402 and
Blood Compartment 404 are the regions of ingress and egress of
dialysate and blood through Dialysate Inlet/Outlet Ports 110 and
Blood Inlet/Outlet Ports 118 respectively. Annular Inner Lip 410
and Annular Outer Lip 412 of Housing 102 receives Annular Tongue
316 in an interference based snap fit fashion. This connection is
spin welded as described above. Typically spin welding of
polypropylene does not generally produce extensive spin welding
particulate, but material does aggregate around the weld joint in
the form of jagged flash (melted polymeric material) which aids in
sealing welded parts together. Annular Channel 320 and Annular
Channel 408 accommodate the flow of some of the melted flash
material that is displaced during the spin welding process.
[0033] After the potting and cutting process, in similar fashion
Annular Interior Rim 414 and Annular Exterior Rim 416 form an
annular groove for receiving Annular Outer Rim 312 of Ring 108.
This connection is spin welded as described above. Annular Channel
406 also accommodates the flow of some of the melted material that
is displaced during the spin welding process. Annular Channel 422
is a specially designed area where Flange Cap 106 and Ring 108 seal
off against each other during the spin welding process, entrapping
additional amounts of melted flash material from the spin welding
process. This design insures that no flash material is allowed to
invade Blood Compartment 404. Blood tends to coagulate on any rough
surface exposed within Blood Compartment 404, which would degrade
the functioning of Filter Device 100. One skilled in the art will
recognize that Annular Channel 422 will also trap residue material
from the other types of joining techniques mentioned above. The
flat annular portions seal up against each other and ensure that
the flash produced will not be introduced into the blood
compartment of Filter Device 100. However, the welding occurs only
at the designated region and not at the flat annular regions where
additional amounts of flash may be generated. Additional regions
that are designed to contain spin weld flash, or residue material
from other types of joining techniques, are located around the
Housing 102/Ring 108 weld interface as Annular Outer Lip 412
extends up from Housing 102 along the exterior of Ring 108, and
around the Flange Cap 106/Ring 108 weld interface as Annular
Exterior Rim 416 extends down from Flange Cap 106 along the
exterior of Ring 108. These areas also minimize the flow of flash,
or residue material from other types of joining techniques, outside
of Filter Device 100 improving the aesthetic features.
[0034] The results of various studies on Filter Device 100 show
that the design of Ring 108 provides an excellent surface for the
corona discharge treatment prior to potting. Extensive quality and
delamination testing from two separate experiments of nearly 600
separate Filter Device 100 samples determined that the current
design would have a 0.00% chance of delaminating with an upper
binomial confidence level of 0.09%. Extensive testing shows that
the design of Filter Device 100 possesses excellent capability of
resisting delamination, possesses high performance characteristics,
and has significantly reduced manufacturing costs. In addition, the
clearance characteristics of Filter Device 100 are among the
highest currently available on the market.
[0035] Having described the present invention, it will be
understood by those skilled in the art that many and widely
differing embodiments and applications of the invention will
suggest themselves without departing from the scope of the present
invention.
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