Microfluidic device

Abstract

Described herein are particular embodiments relating to a microfluidic device that may be utilized for cell sensing, counting, and/or sorting. Particular aspects relate to a microfabricated device that is capable of differentiating single cell types from dense cell populations. One particular embodiment relates a device and methods of using the same for sensing, counting, and/or sorting leukocytes from whole, undiluted blood samples.

1 . A microfluidic apparatus comprising a substrate with a first channel having a defined physical feature, wherein said first channel is in fluid communication with at least one inlet for receiving a fluid, wherein said first channel leads to a restrictive access, and wherein said first channel is in fluid communication with a second channel having a defined physical feature, wherein said second channel is in fluid communication with at least one fluid flow outlet; and a fluid biological sample. 
     
     
         2 . The microfluidic apparatus of  claim 1  wherein said defined physical feature is a depression or protrusion. 
     
     
         3 . The microfluidic apparatus of  claim 1 , wherein said fluid biological sample comprises blood. 
     
     
         4 . The microfluidic apparatus of  claim 1 , further comprising a detection zone in fluid communication with said channel and said fluid flow outlet. 
     
     
         5 . A microfluidic apparatus comprising a substrate with a first channel having a defined physical feature; a first inlet formed in said first channel for receiving a first fluid;
 wherein said first channel is in fluid communication with a bifurcated second channel, wherein said bifurcated channel is in fluid communication with a third channel detection zone; at least one second inlet for receiving a second fluid, wherein said second inlet is in fluid communication with a branched channel; a filter structure in fluid communication with a reservoir, wherein said reservoir is in fluid communication with said third channel detection zone; at least one fluid flow outlet formed in said third channel; and a fluid sample; wherein the ratio of the cross-sectional area of said second channel compared to the cross-sectional area of said first channel is 1:10.   
     
     
         6 . The microfluidic apparatus of  claim 5  wherein said defined physical feature is a depression or a protrusion. 
     
     
         7 . The microfluidic apparatus of  claim 5 , wherein said filter structure comprises a filter array. 
     
     
         8 . The microfluidic apparatus of  claim 5 , wherein said first fluid comprises sheath fluid and said second fluid comprises blood. 
     
     
         9 . A detection system comprising the microfluidic apparatus of  claim 1  or  claim 5  and further comprising a light source; a lens assembly; a filter assembly; and an image capture device. 
     
     
         10 . The detection system of  claim 9 , further comprising at least one display unit or at least one recording unit. 
     
     
         11 . The detection system of  claim 9 , wherein said excitation source comprises a laser. 
     
     
         12 . The detection system of  claim 11 , wherein said laser comprises an argon laser. 
     
     
         13 . The detection system of  claim 9 , wherein said filter assembly comprises an excitation filter, and at least one emission filter. 
     
     
         14 . The detection system of  claim 13 , wherein said filter assembly further comprises at least one aperture and at least one neutral density filter. 
     
     
         15 . The detection system of  claim 13 , wherein said filter assembly further comprises at least one glass polarizer. 
     
     
         16 . The detection system of  claim 9 , wherein said lens assembly comprises at least one condenser lens, at least one objective lens, and at least one beamsplitter. 
     
     
         17 . The detection system of  claim 9 , wherein said image capture device comprises at least one CCD camera, CMOS device, photodiode, or photomultiplier tube. 
     
     
         18 . The detection system of  claim 9 , wherein said filter assembly comprises at least two emission filters and said image capture device comprises at least one photomultiplier tube. 
     
     
         19 . The detection system of  claim 9 , wherein said display unit comprises a computer and said recording unit comprises an oscilloscope. 
     
     
         20 . The detection system of  claim 9 , wherein said excitation source comprises an argon laser; said lens assembly comprises a condenser lens, an objective lens, and a beamsplitter; said filter assembly comprises an excitation filter, a pinhole aperture and a neutral density filter, and at least one emission filter; said image capture device comprises a CCD camera and a photodiode, and said display unit comprises a personal computer, and further comprising an amplifier. 
     
     
         21 . The detection system of  claim 9 , wherein said excitation source comprises an argon laser; said lens assembly comprises a condenser lens, an objective lens, and a beamsplitter, said filter assembly comprises an excitation filter, at least one emission filter; said image capture device comprises a photomultiplier tube, and said display unit comprises a personal computer. 
     
     
         22 . A method for identifying a target comprising providing a fluid sample to at least one microfluidic apparatus, wherein said fluid sample contains at least one dye; providing an excitation source to induce at least one fluorescent signal in a target; detecting the fluorescent signal using a sensor in the apparatus; and identifying the target based in part on the analysis of the fluorescent signal. 
     
     
         23 . The method of  claim 22  wherein said target is selected from the group consisting of: cells, organelles, nuclei, granules, DNA, and RNA. 
     
     
         24 . The method of  claim 22  wherein said target comprises a cell selected from the group consisting of a monocyte, a granulocyte, a macrophage, a neutrophil, an eosinophil, a basophil, or other leukocyte. 
     
     
         25 . The method of  claim 22  wherein said target comprises a leukocyte and said dye comprises acridine orange. 
     
     
         26 . The method of  claim 22  further comprising counting or sorting the target in the sample by analysis of the fluorescent signal. 
     
     
         27 . The method of  claim 22 , wherein said fluid sample comprises blood.