Devices and Methods for Flow Control in Microfluidic Structures

Abstract

An apparatus for controlling flow in a fluid flow path can include a chamber containing an expandable material, the expandable material being configured to expand out of the chamber into a portion of the fluid flow path so as to at least partially block the fluid flow path. The apparatus also can include at least one structure providing flow communication between the chamber and the fluid flow path. The at least one structure can be configured to pass the expandable material from the chamber to the portion of the fluid flow path during expansion so as to control a rate at which the expandable material expands into the portion of the fluid flow path.

1 . An apparatus for controlling flow in a fluid flow path, the apparatus comprising:
 a chamber containing an expandable material, the expandable material being configured to expand out of the chamber into a portion of the fluid flow path so as to at least partially block the fluid flow path; and   at least one structure providing flow communication between the chamber and the fluid flow path, the at least one structure being configured to pass the expandable material from the chamber to the portion of the fluid flow path during expansion so as to control a rate at which the expandable material expands into the portion of the fluid flow path.   
     
     
         2 . The apparatus of  claim 1 , wherein the expandable material comprises a material configured to expand upon contact with water. 
     
     
         3 . The apparatus of  claim 1 , wherein, in an expanded state, the expandable material is permeable to at least some molecules. 
     
     
         4 . The apparatus of  claim 1 , wherein the expandable material comprises a hydrogel. 
     
     
         5 . The apparatus of  claim 1 , wherein the expandable material comprises polycrylamide. 
     
     
         6 - 8 . (canceled) 
     
     
         9 . The apparatus of  claim 1 , wherein the at least one structure comprises a grating configured to extrude the expandable material from the chamber into the portion of the fluid flow path. 
     
     
         10 . The apparatus of  claim 1 , further comprising a flow bypass mechanism configured to flow fluid into the chamber such that the fluid bypasses the at least one structure. 
     
     
         11 . The apparatus of  claim 10 , wherein the flow bypass mechanism comprises at least one capillary mechanism. 
     
     
         12 . The apparatus of  claim 10 , wherein the flow bypass mechanism is in flow communication with the fluid flow path. 
     
     
         13 . The apparatus of  claim 10 , wherein the flow bypass mechanism is configured to receive fluid that flows along the fluid flow path. 
     
     
         14 . The apparatus of  claim 10 , wherein the flow bypass mechanism is configured to flow fluid to the chamber for expanding the expandable material. 
     
     
         15 . (canceled) 
     
     
         16 . A microfluidic device comprising:
 at least one apparatus as set forth in  claim 1 ; and   at least one additional chamber in flow communication with the fluid flow path, the at least one additional chamber being configured to receive a fluid for biological testing.   
     
     
         17 . (canceled) 
     
     
         18 . The microfluidic device of  claim 16 , wherein the at least one additional chamber includes a plurality of additional chambers in flow communication with one another via at least one channel. 
     
     
         19 . A method of controlling flow in a microfluidic device, the method comprising:
 flowing a substance along a fluid flow path of the microfluidic device;   expanding an expandable material into a portion of the fluid flow path so as to at least partially block the fluid flow path; and   passing the expandable material through a structure in flow communication with the portion of the fluid flow path so as to control a rate at which the expandable material expands into the portion of the fluid flow path.   
     
     
         20 . The method of  claim 19 , wherein the passing the expandable material through the structure includes passing the expandable material through a structure in flow communication with the portion of the fluid flow path so as to passively control the rate at which the expandable material expands into the portion of the fluid flow path. 
     
     
         21 . The method of  claim 19 , wherein expanding the expandable material comprises contacting the expandable material with the substance. 
     
     
         22 . An apparatus for controlling flow in a fluid flow path, the apparatus comprising:
 a chamber containing an expandable material, the expandable material being configured to expand out of the chamber into a portion of the fluid flow path so as to at least partially block the fluid flow path; and   at least one structure providing flow communication between the chamber and the fluid flow path, the at least one structure being configured to extrude the expandable material from the chamber to the portion of the fluid flow path during expansion.   
     
     
         23 . The apparatus of  claim 22 , wherein the at least one structure is configured to control a rate at which the expandable material expands into the portion of the fluid flow path. 
     
     
         24 . The apparatus of  claim 23 , wherein the at least one structure is configured to passively control the rate at which the expandable material expands into the portion of the fluid flow path. 
     
     
         25 . The apparatus of  claim 22 , wherein the fluid flow path comprises a microfluidic fluid flow path.