Patent ID: 8765456

Claim:
A microscale apparatus for separating cells having different characteristic dimensions, the apparatus comprising a body, a cover, and a separation element, the body and cover defining a void having an inlet region, an outlet region, and a surface, the separation element i) being disposed in the void, ii) having a plurality of steps including a first step and a second step, and iii) defining a narrow passageway that fluidly connects the inlet and outlet regions in a fluid path, the narrow passageway including a first passageway and a second passageway, the first passageway fluidly connecting the inlet region and the second passageway, being bounded by the first step and the surface of the void, and having a height defined by the distance between the first step and the surface of the void, and the second passageway fluidly connecting the first passageway and the outlet region, being bounded by the second step and the surface of the void, and having a height defined by the distance between the second step and the surface of the void, wherein the width of the narrow passageway at the portion of the second step nearest the inlet region in the fluid path is greater than the height of the second passageway, the height of the second passageway being a) smaller than the height of the first passageway, b) larger than the characteristic dimension of at least some of the cells and c) smaller than the characteristic dimension of at least other of the cells.