Apparatus and method for performing microfluidic manipulations for chemical analysis and synthesis

Abstract

A microchip laboratory system and method provide fluid manipulations for a variety of applications, including sample injection for microchip chemical separations. The microchip is fabricated using standard photolithographic procedures and chemical wet etching, with the substrate and cover plate joined using direct bonding. Capillary electrophoresis and electrochromatography are performed in channels formed in the substrate. Analytes are loaded into a four-way intersection of channels by electrokinetically pumping the analyte through the intersection, followed by switching of the potentials to force an analyte plug into the separation channel.

What is claimed is:  
     
         1 . A microfluidic device, comprising: 
 a. a body having disposed therein: 
 i. at least first, second, third and fourth channels communicating at a first channel intersection, wherein the at least first, second, third and fourth channels are covered by a cover plate;  
 ii. at least first, second, third, and fourth reservoirs; and  
 iii. wherein the first channel connects the first reservoir to the first channel intersection, the second channel connects the second reservoir to the first channel intersection, the third channel connects the third reservoir to the first channel intersection, and the fourth channel connects the fourth reservoir to the first channel intersection; and  
   b. at least first, second, third and fourth electrodes disposed in separate electrical contact with each of the first, second, third, and fourth reservoirs, respectively, but not disposed in the channels, at least the first, second, and third electrodes simultaneously having a controlled electrical potential associated therewith.    
     
     
         2 . The microfluidic device of  claim 1 , wherein the fourth separate electrode is grounded.  
     
     
         3 . The microfluidic device of  claim 1 , wherein each of the first, second, third and fourth electrodes simultaneously have a controlled electrical potential associated therewith.  
     
     
         4 . The microfluidic device of  claim 1 , wherein each of the first, second, third and fourth electrodes comprises an electrical wire that is inserted into the first, second, third and fourth reservoirs, respectively.  
     
     
         5 . The microfluidic device of  claim 1 , wherein the controlled electrical potentials associated with each of the first, second and third electrodes are supplied by at least a first voltage controller separately electrically coupled to each of the first, second and third electrodes.  
     
     
         6 . The microfluidic device of  claim 1 , wherein the body comprises a substrate layer selected from glass, quartz, fused silica, plastic or silicon substrates.  
     
     
         7 . The microfluidic device of  claim 6 , wherein the substrate layer is glass.  
     
     
         8 . The microfluidic device of  claim 6 , wherein the substrate layer is fused silica.  
     
     
         9 . The microfluidic device of  claim 6 , wherein the substrate layer is plastic.  
     
     
         10 . The microfluidic device of  claim 6  further comprising an insulating coating.  
     
     
         11 . The microfluidic device of  claim 1 , wherein and interior surface of at least one of said at least first, second, third and fourth channels is modified.  
     
     
         12 . The microfluidic device of  claim 11 , wherein the interior surface is modified with a chemical coating.  
     
     
         13 . The microfluidic device of  claim 12 , wherein the chemical coating comprises a polymer covalently coupled to the interior surface.  
     
     
         14 . The microfluidic device of  claim 13 , wherein the polymer comprises an alkyl chain.  
     
     
         15 . The microfluidic device of  claim 13 , wherein the polymer comprises a linear polyacrylamide.  
     
     
         16 . The microfluidic device of  claim 1 , wherein the body comprises at least two planar substrates directly bonded together, and wherein the at least first, second, third and fourth channels are defined between the two planar substrates.  
     
     
         17 . The microfluidic device of  claim 1 , wherein each of the first, second, third, and fourth channels comprises a cross-sectional dimension from 1 to 100 μm.  
     
     
         18 . The microfluidic device of  claim 1  further comprising a fifth channel and a fifth reservoir, wherein the fifth channel connects the fifth reservoir to the first channel at a second intersection.  
     
     
         19 . The microfluidic device of  claim 18  further comprising a sixth channel and a sixth reservoir, the sixth channel connecting the sixth reservoir to the second intersection.  
     
     
         20 . The microfluidic device of  claim 18  further comprising a sixth channel and a sixth reservoir, the sixth channel connecting the sixth reservoir to the first channel at a third intersection.  
     
     
         21 . The microfluidic device of  claim 1  further comprising a sieving medium disposed within at least one of the first, second, third and fourth channels.  
     
     
         22 . The microfluidic device of  claim 21 , wherein the sieving medium is selected from acrylamide and cellulose polymers.  
     
     
         23 . The microfluidic device of  claim 21 , wherein the sieving medium is a polyacrylamide polymer.  
     
     
         24 . The microfluidic device of  claim 23 , wherein the acrylamide polymer is a linear polyacrylamide polymer.  
     
     
         25 . The microfluidic device of  claim 21 , wherein the sieving medium is a cellulose polymer.  
     
     
         26 . The microfluidic device of  claim 25 , wherein the sieving medium is hydroxyethylcellulose.  
     
     
         27 . The microfluidic device of  claim 1 , wherein the fourth channel comprises a straight channel.  
     
     
         28 . The microfluidic device of  claim 1 , wherein the fourth channel comprises a serpentine channel.  
     
     
         29 . The microfluidic device of  claim 1 , wherein the body comprises a planar substrate and a cover layer.  
     
     
         30 . The microfluidic device of  claim 1 , wherein the body comprises a substrate layer having the channels disposed in a surface thereof, and a cover layer bonded to the surface of the substrate layer and covering the channels.  
     
     
         31 . The microfluidic device of  claim 30 , wherein the substrate layer and the cover layer are directly bonded.  
     
     
         32 . The microfluidic device of  claim 30 , wherein the cover layer is selected from glass, quartz, fused silica, plastic or silicon substrates.  
     
     
         33 . The microfluidic device of  claim 1 , wherein the electrodes comprise platinum.  
     
     
         34 . The microfluidic device of  claim 1 , wherein the electrodes comprise wires inserted into the reservoirs.  
     
     
         35 . The microfluidic device of  claim 1 , wherein the first, second, third and fourth electrodes are in contact with a fluid disposed within the first, second, third and fourth reservoirs, respectively.  
     
     
         36 . The microfluidic device of  claim 1  further comprising at least a first sample material fluid disposed in the first reservoir.  
     
     
         37 . The microfluidic device of  claim 36 , wherein the sample material comprises ionic species having electrophoretic mobility.  
     
     
         38 . The microfluidic device of  claim 36 , wherein the sample material comprises non-ionic species having no electrophoretic mobility.  
     
     
         39 . The microfluidic device of  claim 36 , wherein the sample material comprises nucleic acids.  
     
     
         40 . The microfluidic device of  claim 39 , wherein the nucleic acids comprise DNA.  
     
     
         41 . The microfluidic device of  claim 39 , wherein the nucleic acids comprise restriction enzyme digest fragments of nucleic acids.  
     
     
         42 . The microfluidic device of  claim 39 , wherein the nucleic acids comprise different size nucleic acids.  
     
     
         43 . The microfluidic device of  claim 42 , wherein the different size nucleic acids are produced in a sequencing reaction.  
     
     
         44 . The microfluidic device of  claim 36 , wherein the sample material comprises protein.  
     
     
         45 . The microfluidic device of  claim 36 , wherein the sample material comprises a fluorescent label.  
     
     
         46 . The microfluidic device of  claim 45 , wherein the fluorescent label comprises a fluorescein dye.  
     
     
         47 . The microfluidic device of  claim 45 , wherein the fluorescent label comprises a rhodamine dye.  
     
     
         48 . The microfluidic device of  claim 36 , wherein the sample material comprises nucleic acids and a fluorescent intercalating dye.  
     
     
         49 . The microfluidic system comprising: 
 a. a microfluidic device of  claim 1;  and    b. a voltage controller separately electrically connected to the first, second, third and fourth electrodes.    
     
     
         50 . The microfluidic system of  claim 49  further comprising an optical detector disposed adjacent at least one of the first, second, third and fourth channels, for receiving an optical signal from the at least one channel.  
     
     
         51 . The microfluidic system of  claim 50 , wherein the optical detector comprises a fluorescence detector.  
     
     
         52 . The microfluidic system of  claim 51 , wherein the fluorescence detector comprises a light source for exciting a fluorescent species disposed in the at least one channel and a detection system for detecting excited fluorescence emitted from the at least one channel.  
     
     
         53 . The microfluidic system of  claim 52 , wherein the light source comprises a laser.  
     
     
         54 . The microfluidic system of  claim 53 , wherein the laser comprises an argon laser.  
     
     
         55 . The microfluidic system of  claim 52 , wherein the light source comprises a light emitting diode.  
     
     
         56 . The microfluidic system of  claim 52 , wherein the light source comprises a diode laser.  
     
     
         57 . The microfluidic device of  claim 52 , wherein the light source comprises a gas discharge lamp.  
     
     
         58 . The microfluidic system of  claim 52 , wherein the detection system comprises a PMT.  
     
     
         59 . The microfluidic system of  claim 52 , wherein the fluorescence detector comprises an array detector.  
     
     
         60 . The microfluidic system of  claim 59 , wherein the array detector comprises a charge coupled device (CCD).  
     
     
         61 . The microfluidic system of  claim 52 , wherein the detection system comprises a spatial filter.  
     
     
         62 . The microfluidic system of  claim 52 , wherein the detection system comprises a spectral filter.  
     
     
         63 . The microfluidic system of  claim 50  further comprising a computer coupled to the detector for acquiring data from the detector.  
     
     
         64 . The microfluidic system of  claim 50 , wherein the optical detector comprises a Raman spectrometer.  
     
     
         65 . The microfluidic system of  claim 49  further comprising a computer for controlling the application of voltages to the at least first, second and third electrodes.  
     
     
         66 . A microfluidic device, comprising: 
 a. a body having disposed therein: 
 i. at least first, second, third and fourth channels communicating at at least a first intersection, wherein the at least first, second, third and fourth channels are covered by a cover plate;  
 ii. at least first, second, third and fourth reservoirs; and  
 iii. wherein the first channel connects the first reservoir to at least a first intersection, the second channel connects the second reservoir to the at least first intersection, the third channel connects the third reservoir to the at least first intersection and the fourth channel connects the fourth reservoir to the at least first intersection; and  
   b. a plurality of electrodes in electrical contact with the channels, wherein the electrical contact consists of a separate electrode disposed in each of the at least first, second, third and fourth reservoirs, wherein at least three of the plurality of electrodes simultaneously have an electrical potential associated therewith.    
     
     
         67 . A microfluidic device, comprising: 
 a. a body having disposed therein: 
 i. at least first, second, third, fourth and fifth channels communicating at at least a first intersection, wherein the at least first, second, third, fourth and fifth channels are covered by a cover plate;  
 ii. at least first, second, third, fourth and fifth reservoirs; and  
 iii. wherein the first channel connects the first reservoir to at least a first intersection, the second channel connects the second reservoir to the at least first intersection, the third channel connects the third reservoir to the at least first intersection, the fourth channel connects the fourth reservoir to the at least first intersection, and the fifth channel connects the fifth reservoir to the at least first intersection; and  
   b. a plurality of electrodes in electrical contact with the channels, wherein the electrical contact consists of a separate electrode disposed in each of the at least first, second, third, fourth and fifth reservoirs, wherein at least three of the plurality of electrodes simultaneously have an electrical potential associated therewith.    
     
     
         68 . The microfluidic device of  claim 67 , wherein the body comprises a substrate layer selected from glass, quartz, fused silica, plastic or silicon substrates.  
     
     
         69 . The microfluidic device of  claim 68 , wherein the substrate layer is glass.  
     
     
         70 . The microfluidic device of  claim 68 , wherein the substrate layer is fused silica.  
     
     
         71 . The microfluidic device of  claim 68 , wherein the substrate layer is plastic.  
     
     
         72 . The microfluidic device of  claim 67  further comprising a sieving medium disposed within at least one of the first, second, third and fourth channels.  
     
     
         73 . The microfluidic device of  claim 72 , wherein the sieving medium is selected from acrylamide and cellulose polymers.  
     
     
         74 . The microfluidic device of  claim 72 , wherein the sieving medium is a polyacrylamide polymer.  
     
     
         75 . The microfluidic device of  claim 74 , wherein the acrylamide polymer is a linear polyacrylamide polymer.  
     
     
         76 . The microfluidic device of  claim 67 , wherein the body comprises a planar substrate and a cover layer.  
     
     
         77 . The microfluidic device of  claim 67 , wherein the body comprises a substrate layer having the channels disposed in a surface thereof, and a cover layer bonded to the surface of the substrate layer and covering the channels.  
     
     
         78 . The microfluidic device of  claim 67 , wherein the first, second, third and fourth electrodes are in contact with a fluid disposed within the first, second, third and fourth reservoirs, respectively.  
     
     
         79 . The microfluidic device of  claim 67 , further comprising at least a first sample material fluid disposed in the first reservoir.  
     
     
         80 . The microfluidic device of  claim 79 , wherein the sample material comprises ionic species having electrophoretic mobility.  
     
     
         81 . The microfluidic device of  claim 79 , wherein the sample material comprises non-ionic species having no electrophoretic mobility.  
     
     
         82 . The microfluidic device of  claim 79 , wherein the sample material comprises nucleic acids.  
     
     
         83 . The microfluidic device of  claim 82 , wherein the nucleic acids comprise DNA.  
     
     
         84 . The microfluidic device of  claim 82 , wherein the nucleic acids comprise restriction enzyme digest fragments of nucleic acids.  
     
     
         85 . The microfluidic device of  claim 82 , wherein the nucleic acids comprise different size nucleic acids.  
     
     
         86 . The microfluidic device of  claim 85 , wherein the different size nucleic acids are produced in a sequencing reaction.  
     
     
         87 . The microfluidic device of  claim 79 , wherein the sample material comprises protein.  
     
     
         88 . The microfluidic device of  claim 79 , wherein the sample material comprises a fluorescent label.  
     
     
         89 . The microfluidic device of  claim 79 , wherein the fluorescent label comprises a fluorescein dye.  
     
     
         90 . A microfluidic device, comprising: 
 a. a body having disposed therein: 
 i. at least first, second, third and fourth channels communicating at a first channel intersection, wherein the at least first, second, third and fourth channels are covered by a cover plate;  
 ii. at least first, second, third and fourth reservoirs; and  
 iii. wherein the first reservoir is in fluid communication with the first intersection via the first channel, the second reservoir is in fluid communication with the first intersection via the second channel, the third reservoir is in fluid communication with the first channel intersection via the third channel, and the fourth reservoir is in fluid communicating with the first channel intersection via the fourth channel; and  
   b. at least first, second, third and fourth electrodes disposed in separate electrical contact with each of the first, second, third, and fourth reservoirs, respectively, but not disposed in the channels, at least the first, second, and third electrodes simultaneously having a controlled electrical potential associated therewith.    
     
     
         91 . The microfluidic device of  claim 90 , wherein the body comprises a substrate layer selected from glass, quartz, fused silica, plastic or silicon substrates.  
     
     
         92 . The microfluidic device of  claim 91 , wherein the substrate layer is glass.  
     
     
         93 . The microfluidic device of  claim 91 , wherein the substrate layer is fused silica.  
     
     
         94 . The microfluidic device of  claim 91 , wherein the substrate layer is plastic.  
     
     
         95 . The microfluidic device of  claim 90  further comprising a sieving medium disposed within at least one of the first, second, third and fourth channels.  
     
     
         96 . The microfluidic device of  claim 95 , wherein the sieving medium is selected from acrylamide and cellulose polymers.  
     
     
         97 . The microfluidic device of  claim 95 , wherein the sieving medium is a polyacrylamide polymer.  
     
     
         98 . The microfluidic device of  claim 95 , wherein the acrylamide polymer is a linear polyacrylamide polymer.  
     
     
         99 . The microfluidic device of  claim 68 , wherein the body comprises a planar substrate and a cover layer.  
     
     
         100 . The microfluidic device of  claim 68 , wherein the body comprises a substrate layer having the channels disposed in a surface thereof, and a cover layer bonded to the surface of the substrate layer and covering the channels.  
     
     
         101 . The microfluidic device of  claim 68 , wherein the first, second, third and fourth electrodes are in contact with a fluid disposed within the first, second, third and fourth reservoirs, respectively.  
     
     
         102 . The microfluidic device of  claim 68  further comprising at least a first sample material fluid disposed in the first reservoir.  
     
     
         103 . The microfluidic device of  claim 102 , wherein the sample material comprises ionic species having electrophoretic mobility.  
     
     
         104 . The microfluidic device of  claim 102 , wherein the sample material comprises non-ionic species having no electrophoretic mobility.  
     
     
         105 . The microfluidic device of  claim 102 , wherein the sample material comprises nucleic acids.  
     
     
         106 . The microfluidic device of  claim 105 , wherein the nucleic acids comprise DNA.  
     
     
         107 . The microfluidic device of  claim 105 , wherein the nucleic acids comprise restriction enzyme digest fragments of nucleic acids.  
     
     
         108 . The microfluidic device of  claim 105 , wherein the nucleic acids comprise different size nucleic acids.  
     
     
         109 . The microfluidic device of  claim 108 , wherein the different size nucleic acids are produced in a sequencing reaction.  
     
     
         110 . The microfluidic device of  claim 102 , wherein the sample material comprises protein.  
     
     
         111 . The microfluidic device of  claim 102 , wherein the sample material comprises a fluorescent label.  
     
     
         112 . The microfluidic device of  claim 102 , wherein the fluorescent label comprises a fluorescein dye.