Apparatus and method for small-volume fluid manipulation and transportation

Abstract

A microfluidic system has an electroosmotic flow pumping means for propelling fluids through a series of microchannels and selection valves. Pump channels are configured in groups which may be fabricated singly or in multiple groups onto a substrate. A tube filled with an immobilized polymer provides a means to apply voltages across pump channels, while prevents passages of fluids through it. It also avoids electrolysis and bubble formation in or close to the microfluidic channels. The selection valves provide for routing functions within the microfluidic system and can also be configured to route fluids outside the system. A rate monitoring system is provided for determining and compensating for flow rates. In one application the microfluidic system may be configured to operate as a small volume pipettor or other fluid transport or analysis device. A micro-dialysis jacket is additionally provided to permit desalting, pH adjustment, concentration adjustment, and other functions.

1 : A microfluidic system, comprising: 
 a substrate;    a fluid network disposed on the substrate for transporting fluids, said fluid network comprising a first segment and a second segment in fluid communication; and    an electrical source coupled across the first segment of the fluid network to apply an electric potential to induce electroosmotic flow in the first segment;    a coupler filled with a chemically immobilized polymer medium inside for introducing electric potential from the electrical source to the first segment and directing flow between the first segment and second segment of the fluid network to cause a flow in the second segment in the presence of electroosmotic flow in the first segment.    
     
     
         2 : A microfluidic system as in  claim 1 , wherein the fluid network comprises at least one fluid channel.  
     
     
         3 : A microfluidic system as in  claim 1 , wherein the first segment of the fluid network comprises a plurality of fluid channels operatively connected on both ends to a single fluid channel.  
     
     
         4 : A microfluidic system as in  claim 1 , wherein the electrical source includes a first electrode reservoir and a second electrode reservoir, operatively connected to a first end and a second end, respectively, of the first segment of the fluid network, wherein the second end of the first segment is fluid coupled to the second segment.  
     
     
         5 : A microfluidic system as in  claim 4 , wherein the second electrode reservoir is electrically connected to the second end of the first segment through the immobilized polymer medium inside the coupler to apply electric potential to the first segment without inducing electrolysis in the fluid network.  
     
     
         6 : A microfluidic system as in  claim 1 , further comprising a valve and a second segment that has a plurality of output channels, where the valve routes fluid from the first segment to one of the plurality of output channels of the second segment.  
     
     
         7 : A microfluidic system as in  claim 1 , further comprising a valve and a first segment that has a plurality of fluid pumping units, wherein the valve routes fluid from the second segment to one of the plurality of the pumping units of the first segment.  
     
     
         8 : A microfluidic system as in  claim 1 , wherein the second segment comprises an isolation channel preventing contamination of fluids between the first and second segment.  
     
     
         9 : A microfluidic system as in  claim 1 , further comprising a pipette discharge.  
     
     
         10 : A microfluidic system as in  claim 1 , wherein the second segment comprises at least one double-T injector.  
     
     
         11 : A device as in  claim 10 , further comprising at least one HPLC column.  
     
     
         12 : A device as in  claim 10 , further comprising at least one freeze/thaw valve.  
     
     
         13 : A device as in  claim 10 , further comprising at least one detection system of a ultraviolet-visible absorbance detector, a fluorescence detector, a laser-induced fluorescence detector, a mass spectrometer, an electrochemical detector, a conductivity detector, a scintillation counter, a radioactive particle intensity detector, a Raman spectrometer, and a light scattering detector.  
     
     
         14 : An electrolysis isolation electrode comprises: 
 a reservoir containing an electrolyte solution inside;    a protective housing;    a polymer medium that is chemically immobilized inside the said protective housing, wherein the polymer medium being such that fluids cannot be transferred through it neither by an electrical means nor by pressure while electrolytes can be transferred through it by an electrical means; and    a metal electrode that is electrically connected to the said polymer medium via the said electrolyte solution inside the said reservoir.    
     
     
         15 : A device as in  claim 14 , wherein the protective housing comprises a flexible tubing.  
     
     
         16 : A device as in  claim 14 , wherein the polymer medium comprises at least one of an agarose gel with a concentration of greater than 0.5% (w/w), a polyacrylamide gel with a concentration of greater than 1% (w/w), sol-gel monoliths, and acrylate polymer monoliths.