Methods and devices for multi-step cell purification and concentration

Abstract

Described herein are microfluidic devices and methods that can separate and concentrate particles in a sample.

What is claimed is: 
     
         1 . A system for separating particles in a sample, comprising:
 a) one or more microfluidic channels for containing fluid flow in a first direction comprising an array of obstacles arranged in rows and columns, wherein the array of obstacles is configured to differentially separate particles based on size; and   b) a dispense module in communication with the one or more microfluidic channels configured to dispense a droplet containing one or more particles, wherein the one or more particles are separated by the array of obstacles in the one or more microfluidic channels.   
     
     
         2 . The system of  claim 1 , wherein the rows define an array direction that differs from the first direction by a tilt angle (ε) of 1/10 radian and wherein the rows repeat periodically and have a periodocity equal to 10 (1/ε). 
     
     
         3 . The system of  claim 1 , wherein the array has a critical size of 4-6 μm. 
     
     
         4 . The system of  claim 1 , wherein the obstacles are circular in shape. 
     
     
         5 . The system of  claim 1 , wherein the one or more microfluidic channels have at least two inlets. 
     
     
         6 . The system of  claim 1 , wherein the dispense module is configured to dispense one particle per droplet. 
     
     
         7 . The system of  claim 1 , further comprising a polymerase chain reaction (PCR) device downstream of the dispense module. 
     
     
         8 . A method for separating particles in a fluid sample comprising passing said fluid sample through the system of  claim 1 . 
     
     
         9 . The method of  claim 8 , wherein the fluid sample comprises T cells. 
     
     
         10 . The method of  claim 9 , wherein the T cells are CD8 cells. 
     
     
         11 . The method of  claim 9 , wherein at least some of the T cells are bound to magnetic particles. 
     
     
         12 . The method of  claim 11 , wherein the magnetic particles have a diameter of 500 nm. 
     
     
         13 . The method of  claim 8 , further comprising passing a buffer stream in parallel with the fluid sample through the system. 
     
     
         14 . The method of  claim 8 , further comprising performing reverse transcriptase PCR on particles dispensed from the dispense module.