Folded membrane dialyzer

Claim 2

A dialyzer comprising: a rectangular housing; a semipermeable membrane disposed within said housing, said membrane being folded into a large number of very closely spaced pleats so as to undulate across the width of said housing, all edges of said membrane being embedded in a nonadhesive plastic material selected from the group consisting of polycarbonate, polypropylene, polyethylene, and polystyrene, said nonadhesive plastic material constituting at least a portion of said housing to form thereby a first fluid chamber on one side of said membrane sealingly separated from a second fluid chamber on the opposite side of said membrane; support members disposed within all pleats on one side only of said membrane; means for passing a first fluid through said first chamber in a direction generally parallel to the creases of said pleats; and means for passing a second fluid through said second chamber countercurrent to the first fluid.

Claim 3

A dialyzer in accordance with claim 1 wherein: said plastic material fills the space along the interior walls of a preconstructed rectangular casing so as to constitute a portion of said housing and so as to surround the edges of said membrane.

Claim 4

The dialyzer according to claim 2 wherein the first pleat and the last pleat in said semipermeable membrane open to the same side of said housing and the support members are disposed in said first pleat, said last pleat, and all other pleats on the same side of said membrane.

Claim 5

The dialyzer according to claim 3 wherein the first pleat and the last pleat in said membrane extend only part way across the width of said houSing, the end-edges of said membrane terminating at a line approximately one-half of the distance across the width of the housing, said plastic material filling said first pleat and said last pleat so as to completely surround said end-edges of said membrane.

Claim 6

A dialyzer in accordance with claim 2 wherein the semipermeable membrane is folded such that those pleats not containing support members therein are essentially closed in the absence of a fluid, the portions of the membrane surface forming the opposite interior walls of each of these pleats being essentially in contact, and opened in the presence of a fluid, these pleats being capable of opening under a fluid pressure which distends the membrane into the support members in the pleats on the opposite side of said membrane.

Claim 7

A dialyzer in accordance with claim 1 wherein: said plastic material constitutes the entire housing, surrounding the edges of the membrane and completely enclosing the entire undulating membrane so as to form a rectangular housing.

Claim 8

A dialyzer in accordance with claim 6 wherein the semipermeable membrane is folded such that those pleats not containing support members therein are essentially closed in the absence of a fluid, the portions of the membrane surface forming the opposite interior walls of each of these pleats being essentially in contact, and opened in the presence of a fluid, these unsupported pleats being capable of opening under a fluid pressure which distends the membrane into the support members disposed in the pleats on the opposite side of said membrane.

Claim 9

A dialyzer in accordance with claim 7 wherein the first pleat and the last pleat in said semipermeable membrane are on the same side of said membrane and the support members are disposed in said first and last pleats and the other pleats on the same side of the membrane; and wherein said dialyzer further comprises a first barrier sheet and a second barrier sheet disposed within said housing on the same side of the membrane as said support members and essentially lying between said supported pleats and the interior side wall of said housing, said first barrier sheet having one edge inserted into the first pleat between the contained support member and the adjacent pleat, said first barrier sheet extending over the membrane pleats towards said last pleat, said second barrier sheet having one edge inserted into the last pleat between the contained support member and the adjacent pleat, said second barrier sheet extending over the membrane pleats towards said first pleat so as to overlap said first barrier sheet, said two barrier sheets lying along the length of the side of the housing so as to cover the openings in the supported pleats parallel to the creases of the pleats and to prevent the plastic material from extending into said supported pleats.

Claim 10

A dialyzer according to claim 8 wherein the first pleat and the last pleat in said membrane extend only part way across the width of said housing, the end-edges of said membrane terminating at a line approximately one-half of the distance across the width of the housing, said plastic material filling said first pleat and said last pleat so as to completely surround said end-edges of said membrane.

Claim 11

A method of making the dialyzer of claim 2 comprising: a. folding a semipermeable membrane into a large number of very closely spaced pleats; b. inserting support members into all pleats on one side of said membrane; c. inserting spacing members into both the first pleat and the last pleat to maintain said first and last pleats substantially opened; d. placing spacing members on the outside of said first pleat and on the outside of said last pleat whereby each of the two end-edges of said membrane lie between spacing members on the outside of the pleat and a spacing member within the pleat; e. placing the above membrane assemblage into a rectangular casing, said rectangular casing having on each of the two side walls thereof an inlet port Near one end and an outlet port near the opposite end, said membrane assemblage being placed such that the two end-edges of the membrane and their associated spacing members are adjacent the top and bottom walls of said casing and said membrane assemblage fits snugly against the top, bottom, and two side walls of said casing while a narrow space is left between the side-edges of the membrane which form the ends of the assemblage and the end walls of the casing; f. injecting into said casing through the top, bottom, and each of the two end walls, a fluid plastic material which flows along said top and bottom walls and fills said substantially opened first and last pleats, thereby completely surrounding said two end-edges of the membrane, and which fills said narrow spaces between said side-edges of the membrane and the end walls of the casing and which flows a short distance into the supported pleats which are held slightly opened by said support members, thereby surrounding said two side-edges of the membrane; and g. solidifying said fluid plastic material whereby all edges of said membrane are embedded in said plastic material which forms a portion of the housing and said housing is divided into two sealingly separate fluid chambers on opposite sides of said membrane.

Claim 12

A method of making the dialyzer of claim 6 comprising: a. folding the semipermeable membrane into a large number of very closely spaced pleats; b. inserting support members into all pleats on one side of said membrane; c. inserting spacing members into both the first pleat and the last pleat to maintain said first and last pleats substantially opened; d. placing spacing members on the outside of said first pleat and on the outside of said last pleat whereby each of the two end-edges of said membrane lie between spacing members on the outside of the pleat and a spacing member within the pleat; e. placing the above membrane assemblage into a rectangular mold of such internal dimensions that the support members about the end-edges of the membrane contact the top and bottom walls of said mold while a narrow gap is left between the membrane assemblage and the two side walls of the mold and between the side-edges of the membrane which form the ends of the assemblage and the two end walls of the mold; f. placing studs in the narrow gap between said membrane assemblage and said mold near each end of each side wall thereof, said studs extending vertically from the first pleat to the last pleat and fitting snugly between the side walls of said mold and said membrane assemblage; g. injecting into said mold a fluid plastic material, said fluid plastic material flowing into and filling said narrow gap between said membrane assemblage and said side walls of said mold between and about said studs, flowing into and filling said narrow gap between the side-edges of the membrane which form the ends of the assemblage and the end walls of said mold and further flowing form this gap a short distance into the supported pleats which are held slightly opened by said support members thereby surrounding said two side-edges of the membrane, and flowing into and about said spacing members and into and filling said substantially opened first and last pleats thereby completely surrounding said two end-edges of said membrane; h. solidifying said fluid plastic material whereby all edges of said membrane are embedded in said plastic material and said plastic material forms a housing about said membrane assemblage, said housing having openings to its interior at the points of contact between said membrane assemblage and said studs; i. removing said housing from said mold; j. removing said studs from said housing to expose said openings to the interior; and k. sealingly mounting access ports on said housing over said openings.

Claim 13

A method according to claim 11 further comprising: prior to placing the membrane assemblage in the mold, placing a first and a second barrier sheet aLong the side of said membrane assemblage on the same side of said membrane as said support members, one edge of said first barrier sheet being inserted between the support member and a membrane wall of the first supported pleat, said first barrier sheet extending over the pleats towards the last pleat, one edge of said second barrier sheet being inserted between the support member and a membrane wall of the last supported pleat, said second barrier sheet extending over the pleats toward the first pleat so as to overlap with said first barrier sheet, said first and second barrier sheets being of such a length so as to extend along the length of the side of the assemblage between said studs.

Claim 14

A method according to claim 12 wherein said membrane is folded such that the first pleat and the last pleat extend only part way across the width of the other pleats, the end-edges of said membrane terminating at a line approximately one-half the distance across the width of the pleats, and the first and last pleats are on the same side of the membrane and have support members inserted therein.