A filtration cell for a biological sample comprising: an outer housing having a first end, a second end, and a sidewall extending therebetween, the sidewall defining a first chamber; and an inner housing having a first end, a second end, and a sidewall extending therebetween, at least one aperture, at least one vertical or horizontal indentation terminating into the at least one aperture and disposed within the sidewall of the inner housing, the sidewall of the inner housing, defining a second chamber, the inner housing being disposed within the first chamber and rotatable with respect to the outer housing and the at least one aperture providing an opening into the second chamber, wherein at least a portion of the inner housing comprises a filtration membrane wherein the filtration membrane is disposed over the at least one aperture; the filtration cell further comprising at least one support region adjacent the at least one indentation for supporting at least a portion of the filtration membrane; wherein upon rotation of the inner housing with respect to the outer housing, the filtration membrane is adapted to allow a first portion of the biological sample to pass from the first chamber into the second chamber wherein the first portion is directed into the second chamber through the at least one aperture along the at least one vertical or horizontal indentation and to restrain a second portion of the biological sample in the first chamber, characterized in that the filtration cell further comprises a biasing member that rotationally biases the inner housing with respect to the outer housing, wherein the biasing member is a compression spring or a torsional spring. an outer housing having a first end, a second end, and a sidewall extending therebetween, the sidewall defining a first chamber; and an inner housing having a first end, a second end, and a sidewall extending therebetween, at least one aperture, at least one vertical or horizontal indentation terminating into the at least one aperture and disposed within the sidewall of the inner housing, the sidewall of the inner housing, defining a second chamber, the inner housing being disposed within the first chamber and rotatable with respect to the outer housing and the at least one aperture providing an opening into the second chamber, wherein at least a portion of the inner housing comprises a filtration membrane wherein the filtration membrane is disposed over the at least one aperture; the filtration cell further comprising at least one support region adjacent the at least one indentation for supporting at least a portion of the filtration membrane; wherein upon rotation of the inner housing with respect to the outer housing, the filtration membrane is adapted to allow a first portion of the biological sample to pass from the first chamber into the second chamber wherein the first portion is directed into the second chamber through the at least one aperture along the at least one vertical or horizontal indentation and to restrain a second portion of the biological sample in the first chamber, characterized in that the filtration cell further comprises a biasing member that rotationally biases the inner housing with respect to the outer housing, wherein the biasing member is a compression spring or a torsional spring.