Method and apparatus for filtering suspensions of medical and biological fluids or the like
First Claim
1. A method for separating red blood cells in whole blood from white blood cells comprising:
- providing a filter membrane having substantially precisely dimensioned pores, said pores being dimensioned to correspond substantially to the shape of a cross section of said red blood cells to allow passage of substantially undeformed red blood cells through said pores while precluding passage of undeformed white blood cells; and
contacting the whole blood and said membrane such that said white cells are in contact with said membrane for a time less than that needed to deform said white blood cells to a size and shape capable of passing through said membrane.
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Abstract
A method and apparatus for filtering suspensions of medical and biological fluids, one aspect of which is separating a suspension comprising at least two types of particles which are differently sized or shaped and in which the first type of particle may be deformable at a relatively lower force and/or faster rate than the second type of particle. A filter member is provided having substantially precisely dimensioned pore sizes, with the pores being dimensioned to allow passage of the first type of suspended particle without distortion or only minimal distortion and passage of the second type of particle only with substantial distortion. Because the filter membrane has precisely dimensioned pores, with spacing between the pores being maintained despite the smaller interval between the pores, the porosity of the membrane may be much greater than nominal pore size membranes, allowing faster filtration rates and/or smaller membranes for a given filtration rate, while reducing the exposure time of the cells within the shear environment, and consequently reducing particle damage. Various methods for preventing clogging of the membrane are also disclosed.
75 Citations
32 Claims
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1. A method for separating red blood cells in whole blood from white blood cells comprising:
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providing a filter membrane having substantially precisely dimensioned pores, said pores being dimensioned to correspond substantially to the shape of a cross section of said red blood cells to allow passage of substantially undeformed red blood cells through said pores while precluding passage of undeformed white blood cells; and
contacting the whole blood and said membrane such that said white cells are in contact with said membrane for a time less than that needed to deform said white blood cells to a size and shape capable of passing through said membrane.
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2. A method for separating red blood cells in whole blood from white blood cells comprising:
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providing a filter membrane having substantially precisely dimensioned pores, said pores being dimensioned to correspond substantially to the shape of a cross section of said red blood cells to allow passage of substantially undeformed red blood cells through said pores while precluding passage of undeformed white blood cells; and
contacting the whole blood and said membrane with a force less than that needed to deform said white blood cells to a size and shape capable of passing through said membrane.
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3. An apparatus for separating red blood cells in whole blood from white blood cells comprising:
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a filter membrane having substantially precisely dimensioned pores, said pores being dimensioned to correspond substantially to the shape of a cross section of said red blood cells to allow passage of substantially undeformed red blood cells through said pores while precluding passage of undeformed white blood cells; and
means for contacting the whole blood in said membrane such that said white cells are in contact with said membrane for a time less than that needed to deform said white blood cells to a size and shape capable of passing through said membrane.
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4. An apparatus for separating red blood cells in whole blood from white blood cells comprising:
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a filter membrane having substantially precisely dimensioned pores, said pores being dimensioned to correspond substantially to the shape of a cross section of said red blood cells to allow passage of substantially undeformed red blood cells through said pores while precluding passage of undeformed white blood cells; and
means for contacting the whole blood and said membrane with a force less than that needed to deform said white blood cells to a size and shape capable of passing through said membrane.
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5. A method for separating a suspension comprising at least first and second types of particles of different shape, the first type of particle being deformable at a relatively lower force than the second type of particle, said method comprising:
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providing a filter membrane having pores with substantially precisely dimensioned shapes and sizes, said pore shapes and sizes being dimensioned to correspond substantially to the shape of said first particle to allow passage of said first type of particle and to block passage of said second type of particle; and
contacting the suspension and said membrane with a force sufficient to allow any required deformation of said first type of particle for passage through said pores and insufficient to allow deformation of said second type of particle for passage through said pores, so as to allow passage of said first type of particle through said pores and to block passage of said second type of particle through said pores. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14)
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6. A method for separating a suspension comprising at least first and second types of particles of different shape, the first type of particle being deformable at a relatively faster rate than the second type of particle, the method comprising:
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providing a filter membrane having pores with substantially precisely dimensioned shapes and sizes, said pore shapes and sizes being dimensioned to correspond substantially to the shape of said first particle to allow passage of said first type of particle and to block passage of said second type of particle; and
contacting the suspension and said membrane such that said first type of particles are in contact with said membrane for a time sufficient to allow any required deformation and passage of said first type of particle through said pores and such that said second type of particle are in contact with said membrane for a time insufficient to allow deformation of said second type of particle for passage through said pores so as to allow passage of said first type of particle through said pores and to block passage of said second type of particle through said pores.
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15. An apparatus for separating a suspension comprising at least first and second types of particles of different shape, said first type of particle being deformable at a relatively faster rate than said second type of particle, said apparatus comprising:
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a filter membrane having pores with substantially precisely dimensioned shapes and sizes, said pore shapes and sizes being dimensioned to correspond substantially to the shape of said first particle to allow passage of said first type of particle and to block passage of said second type of particle; and
means for contacting the suspension and said membrane for a time sufficient to allow any required deformation of said first type of particle for passage through said pores and insufficient to allow deformation of said second type of particle for passage through said pores so as to allow passage of said first type of particle through said pores and to block passage of said second type of particle through said pores. - View Dependent Claims (16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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19. An apparatus for separating a suspension comprising at least first and second types of particles of different shape, said first type of particle being deformable at a relatively lower force than said second type of particle, said apparatus comprising:
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a filter membrane having pores with substantially precisely dimensioned shapes and sizes, said pore shapes and sizes being dimensioned to correspond substantially to the shape of said first particle to allow passage of said first type of particle and to block passage of said second type of particle; and
means for contacting the suspension and said membrane with a force sufficient to allow any required deformation of said first type of particle for passage through said pores and insufficient to allow deformation of said second type of particle for passage through said pores so as to allow passage of said first type of particle through said pores and to block passage of said second type of particle through said pores. - View Dependent Claims (32)
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Specification