Microfluidic Device For Size And Deformability Measurements And Applications Thereof

Abstract

A microfluidic device system includes a channel having an entrance and an exit, a height at the entrance being greater than a height at the exit. The height of the channel may decrease continuously from the height at the entrance to the height at the exit. Cells or particles or beads traveling through the channel become trapped based on their size and/or deformability. A visual sensor captures images of the trapped cells or particles or beads, and image software analyzes the captured images to provide size and/or deformability and/or fluorescence information. A method of fabricating such a microfluidic device includes introducing a glass wafer to an etching solution at a specific rate such that a first end of the glass wafer is etched longer than other portions of the glass wafer.

What is claimed is: 
     
         1 . A method of using a microfluidic assay in a microfluidic device system, the method comprising:
 providing a microfluidic device system having a channel having a height that is greater at an entrance to the channel than a height at an exit of the channel, the channel decreasing in height from the entrance to the exit;   combining a first solution with a target protein and a second solution, wherein
 the first solution comprises a plurality of beads, each bead having a diameter and a surface substantially coated with a first molecule, and, 
 the second solution comprises a second molecule associated with a quantum dot, 
 wherein the first molecule and the second molecule associate with the target protein to form a multiplex on the surface of each of the plurality of beads; 
   trapping each bead of the plurality of beads along the channel based on the diameter of the bead;   capturing an image of the trapped plurality of beads;   sending the image to a data collection/readout device; and   analyzing the image using image software to measure the fluorescence of the multiplex on the surface of at least one of the trapped beads located at one or more locations along the channel.   
     
     
         2 . The method of  claim 1 , wherein the channel has a width equal to or greater than 1000 μm, and a length equal to or greater than 2 cm. 
     
     
         3 . The method of  claim 1 , wherein the channel continuously decreases in height from the entrance to the exit. 
     
     
         4 . The method of  claim 1 , wherein the height at the entrance is at or between 4 μm and 15 μm. 
     
     
         5 . The method of  claim 1 , wherein the height at the exit is at or between 0.5 μm and 8 μm. 
     
     
         6 . The method of  claim 1 , wherein each of the plurality of beads has a diameter of or between 1 μm and 10 μm. 
     
     
         7 . The method of  claim 1 , wherein the target protein comprises glial fibrillary acid protein (GFAP), NF-L, UCH-L1, S-100B, or a mixture thereof. 
     
     
         8 . The method of  claim 1 , wherein the target protein is present at a concentration of or between 0.01 ng/mL and 50 ng/mL. 
     
     
         9 . The method of  claim 1 , wherein the first molecule and/or the second molecule comprises DNA, RNA, or a fragment thereof. 
     
     
         10 . The method of  claim 1 , wherein the first molecule and/or the second molecule comprises a monoclonal antibody or a polyclonal antibody. 
     
     
         11 . The method of  claim 10 , wherein the first molecule is a GFAP monoclonal antibody. 
     
     
         12 . The method of  claim 10 , wherein the second molecule is a GFAP polyclonal antibody. 
     
     
         13 . The method of  claim 1 , wherein the second solution further comprises a linker compound, the linker compound binding the second molecule to the quantum dot. 
     
     
         14 . The method of  claim 13 , wherein the linker compound comprises biotin, protein G, protein A, a carboxyl group, or an epoxy group. 
     
     
         15 . The method of  claim 1 , wherein the quantum dot is present at a concentration of or between 0.1 nM and 1 μM. 
     
     
         16 . The method of  claim 1 , further comprising priming the channel with a priming solution prior to trapping each multiplex along the channel, wherein the priming solution comprises bovine serum albumin (BSA). 
     
     
         17 . The method of  claim 16 , wherein the BSA is present in an amount of or between 1 and 10 wt %, based on the total weight of the priming solution. 
     
     
         18 . The method of  claim 1 , wherein the combining of the first solution with the target protein and the second solution occurs in the channel. 
     
     
         19 . The method of  claim 1 , further comprising a second target protein. 
     
     
         20 . A microfluidic device system ( 2 ) comprising:
 a data collection and readout device ( 4 ) connected to a visual sensor ( 8 ), the visual sensor ( 8 ) operatively connected to a microfluidic device ( 10 ) to capture images within the microfluidic device ( 10 );   an inlet ( 132 ) by which a solution enters the microfluidic device ( 10 ), wherein the inlet ( 132 ) is connected to a supply line ( 14 ) that is connected to a container ( 12 );   wherein the microfluidic device ( 10 ) further comprises a channel ( 126 ) having an entrance ( 128 ) and an exit ( 130 ), a height (H 1 ) at the entrance ( 128 ) being greater than a height (H 2 ) at the exit ( 130 ).   
     
     
         21 . The microfluidic device system ( 2 ) of  claim 20 , wherein the height at the entrance ( 128 ) decreases continuously until reaching the height at the exit ( 130 ). 
     
     
         22 . The microfluidic device system ( 2 ) of  claim 20 , wherein the channel ( 126 ) has a width equal to or greater than 1000 μm. 
     
     
         23 . A method ( 202 ) of using a microfluidic device system comprising:
 introducing an anti-interaction agent to a channel of a microfluidic device ( 204 );   introducing a solution to the channel of the microfluidic device, the channel having a height that is greater at an entrance to the channel than at an exit of the channel, the channel decreasing in height continuously from the entrance to the exit ( 206 );   flowing the solution through the channel ( 208 );   trapping cells or particles within the channel ( 208 );   stopping the flow of the solution through the channel ( 210 );   capturing an image of the trapped cells or particles ( 212 );   sending the image to a data collection/readout device ( 212 );   analyzing the image using image software to determine size or deformability information about the trapped cells or particles ( 214 ).   
     
     
         24 . The method of using the microfluidic device system of  claim 23 , wherein more than one image is captured, each image corresponding with a separate portion of the channel. 
     
     
         25 . The method of using the microfluidic device system of  claim 23 , wherein the size or deformability information identifies a number of subsets having certain sizes or deformability characteristics. 
     
     
         26 . The method of using the microfluidic device system of  claim 25 , wherein the size or deformability information further identifies the relative size of each of the number of subsets. 
     
     
         27 . A method ( 302 ) of fabricating a microfluidic device ( 10 ) comprising:
 preparing a glass wafer for etching ( 304 );   etching the glass wafer by introducing the glass wafer into an etching solution at a specific rate with a first end of the glass wafer being etched longer than subsequent portions of the glass wafer ( 306 );   performing additional etching on the glass wafer by submerging the entire glass wafer, including a previously un-etched portion of the glass wafer, in an etching solution ( 308 );   measuring the etched profile of the glass wafer ( 310 ).   
     
     
         28 . The method of  claim 27 , further comprising:
 drilling an entrance and an exit to the microfluidic device ( 10 ) on a separate glass wafer ( 414 );   bonding the separate glass wafer to the etched glass wafer ( 416 ).   
     
     
         29 . The method of  claim 27 , wherein the etched profile has a target slope, and wherein the specific rate is determined based on the target slope.