Patent ID: 8807879

Claim:
A method for focusing particles suspended within a moving fluid, the method comprising: providing a substrate including at least one channel having an inlet, an outlet, a plurality of sides, wherein the relative geometry of the sides defines an aspect ratio, and a channel hydraulic diameter (D h ); flowing a fluid having a substantially constant kinematic viscosity (v) that includes suspended particles, each having a particle diameter (a), through the at least one channel; and driving the fluid that includes the suspended particles through the at least one channel at a maximum channel velocity (U m ) resulting in a laminar fluid flow and a particle Reynolds Number (R p ) of greater than or equal to 0.2, wherein the particle Reynolds number is defined as, R p =U m α 2 /vD n , and resulting in forming one or more localized stream lines in the fluid; wherein each localized stream line defines a width that is substantially equal to or greater than a size of the focused particles, and the particles suspended in the fluid are focused into the one or more localized stream lines, wherein the number and relative cross-sectional position of the one or more localized stream lines are uniquely defined by the aspect ratio and the particle Reynolds number.