Systems and methods for particle focusing in microchannels

A system for focusing particles suspended within a moving fluid, the system comprising:

• a substrate;
• at least one channel provided on the substrate, the 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 (Dh), wherein the at least one channel is configured to allow a fluid having a substantially constant kinematic viscosity (v) that includes suspended particles, each having a particle diameter (a), to flow therethrough;
• and
• a pumping element designed to drive the fluid that includes the suspended particles through the at least one channel;
• wherein when the fluid that includes the suspended particles is flowed through the at least one channel, and the pumping element drives the fluid that includes the suspended particles at a maximum channel velocity (Um) resulting in a laminar fluid flow and a particle Reynolds Number (Rp)) of greater than or equal to 0.2, wherein the particle Reynolds number is defined as
• R
• p
• =
• U
• m
• ⁢
• a
• 2
• ⁢
• vD
• h
• ,
• one or more localized stream lines are formed 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.