A device for the separation of small particles or cells from a fluid suspension of the same is described. The device includes a coaxial tubular design in which the inner tube is a micro porous tube that allows the passage of liquids and certain particulates up to a certain size cut-off, and the outer tube allows for the collection of passed fluids. Inlet and outlet ports allow the introduction and flushing of components of interest. Embodiments of the device can be used for the separation of blood components, the sequestering of micro spheres used in micro-sphere-based immuno assay, and sample filtration. Other applications are not precluded. Another field of application for this device is in the separation of plasma from red blood cells. The red blood cells will not pass through the membrane due to their size, but plasma will.