A microfluidic device for processing blood comprising: a first network of channels (104; 302, 304, 310; 210) having a plurality of First Channels, each First Channel having a height in the range of 50 microns to 500 microns; a second network of channels having at least one Second Channel complementary to one or more of the First Channels; a filtration membrane separating the one or more First Channels from the at least one Second Channel; wherein the plurality of First Channels further comprises: an input channel forming a primary channel, a plurality of secondary channels (304A...304C), and an outlet channel wherein: a first secondary channel connects to the primary channel at a first junction located at a first distance from a first end of the primary channel; and a second secondary channel connects to the primary channel at a second junction; characterized in that: the second junction is located at a second distance, greater than the first distance, from the first end of the primary channel; the primary channel and the first and second secondary channels are configured such that flow of fluid through the primary channel beyond the first junction is substantially greater than flow of fluid into the first secondary channel; and at least one of the first and second secondary channels bifurcates into first and second tertiary channels (310A, 310B) at a third junction, such that a fluid flow rate through the first tertiary channel is substantially the same as a fluid flow rate through the second tertiary channel, and the total fluid flow rate between the first and second tertiary channels is substantially the same as the fluid flow rate through the portion of the at least one secondary channel between the primary channel and the third junction. a first network of channels (104; 302, 304, 310; 210) having a plurality of First Channels, each First Channel having a height in the range of 50 microns to 500 microns; a second network of channels having at least one Second Channel complementary to one or more of the First Channels; a filtration membrane separating the one or more First Channels from the at least one Second Channel; wherein the plurality of First Channels further comprises: an input channel forming a primary channel, a plurality of secondary channels (304A...304C), and an outlet channel wherein: a first secondary channel connects to the primary channel at a first junction located at a first distance from a first end of the primary channel; and a second secondary channel connects to the primary channel at a second junction; characterized in that: the second junction is located at a second distance, greater than the first distance, from the first end of the primary channel; the primary channel and the first and second secondary channels are configured such that flow of fluid through the primary channel beyond the first junction is substantially greater than flow of fluid into the first secondary channel; and an input channel forming a primary channel, a plurality of secondary channels (304A...304C), and an outlet channel wherein: a first secondary channel connects to the primary channel at a first junction located at a first distance from a first end of the primary channel; and a second secondary channel connects to the primary channel at a second junction; a first secondary channel connects to the primary channel at a first junction located at a first distance from a first end of the primary channel; and a second secondary channel connects to the primary channel at a second junction; characterized in that: the second junction is located at a second distance, greater than the first distance, from the first end of the primary channel; the primary channel and the first and second secondary channels are configured such that flow of fluid through the primary channel beyond the first junction is substantially greater than flow of fluid into the first secondary channel; and the second junction is located at a second distance, greater than the first distance, from the first end of the primary channel; the primary channel and the first and second secondary channels are configured such that flow of fluid through the primary channel beyond the first junction is substantially greater than flow of fluid into the first secondary channel; and at least one of the first and second secondary channels bifurcates into first and second tertiary channels (310A, 310B) at a third junction, such that a fluid flow rate through the first tertiary channel is substantially the same as a fluid flow rate through the second tertiary channel, and the total fluid flow rate between the first and second tertiary channels is substantially the same as the fluid flow rate through the portion of the at least one secondary channel between the primary channel and the third junction.