Microfabricated structures for facilitating fluid introduction into microfluidic devices

• US 6,709,559 B2
• Filed: 07/30/2002
• Issued: 03/23/2004
• Est. Priority Date: 06/06/1997
• Status: Expired due to Term

• Current Assignee: Applied Biosystems LLC (Thermo Fisher Scientific Incorporated)
• Original Assignee: Caliper Technologies Corp (Revvity, Inc.)
• Inventors: Chow, Calvin Y. H., Parce, J. Wallace, Sundberg, Steven A.
• Primary Examiner(s): Olsen, Kaj K.
• Application Number:
  US10/209,493
• Publication Number:
  US 20020179447A1
• Time in Patent Office: 602 Days
• Field of Search: 204/450, 204/453, 204/601, 204/604, 436/180, 422/100
• US Class Current: 204/604
• CPC Class Codes: B01J 19/0093 Microreactors, e.g. miniaturised or microfabricated reactors laboratory containers with capillary fluid transport in microfabricated channels or chambers B01L3/5027
• CPC Class Codes: B01J 2219/00783 Laminate assemblies, i.e. the reactor comprising a stack of plates
• CPC Class Codes: B01J 2219/00826 Quartz
• CPC Class Codes: B01J 2219/00831 Glass
• CPC Class Codes: B01J 2219/00833 Plastic
• CPC Class Codes: B01J 2219/00853 Employing electrode arrangements
• CPC Class Codes: B01J 2219/00891 Feeding or evacuation
• CPC Class Codes: B01J 2219/00909 using filters
• CPC Class Codes: B01L 2200/027 for microfluidic devices
• CPC Class Codes: B01L 2300/0681 Filter
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0819 Microarrays; Biochips
• CPC Class Codes: B01L 2300/0864 comprising only one inlet and multiple receiving wells, e.g. for separation, splitting
• CPC Class Codes: B01L 2400/0406 capillary forces
• CPC Class Codes: B01L 2400/0418 electro-osmotic flow [EOF]
• CPC Class Codes: B01L 2400/0421 electrophoretic flow
• CPC Class Codes: B01L 2400/0487 fluid pressure, pneumatics
• CPC Class Codes: B01L 2400/0688 surface tension valves, capillary stop, capillary break
• CPC Class Codes: B01L 3/0244 using pins
• CPC Class Codes: B01L 3/0262 using touch-off at substrate or container
• CPC Class Codes: B01L 3/5025 : for parallel transport of multiple samples
• CPC Class Codes: B01L 3/50255 : Multi-well filtration
• CPC Class Codes: B01L 3/5027 : by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: B01L 3/502715 : characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
• CPC Class Codes: B01L 3/502723 : characterised by venting arrangements
• CPC Class Codes: B01L 3/50273 : characterised by the means or forces applied to move the fluids micropumps F04B19/006, of the membrane type F04B43/043
• CPC Class Codes: B01L 3/502753 : characterised by bulk separation arrangements on lab-on-a-chip devices, e.g. for filtration or centrifugation separation in general B01D; microapparatus for analysis using electrophoresis G01N27/44791; sample preparation G01N1/28
• CPC Class Codes: G01N 2035/00237 : Handling microquantities of analyte, e.g. microvalves, capillary networks
• CPC Class Codes: G01N 2035/1037 : Using surface tension, e.g. pins or wires
• CPC Class Codes: G01N 27/44743 : Introducing samples
• CPC Class Codes: G01N 27/44791 : Microapparatus sample containers with integrated microfluidic structures B01L3/5027
• CPC Class Codes: Y10T 436/25125 : Digestion or removing interfering materials
• CPC Class Codes: Y10T 436/25375 : Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]
• CPC Class Codes: Y10T 436/2575 : Volumetric liquid transfer

Abstract

Fluid introduction is facilitated through the use of a port which extends entirely through a microfluidic substrate. Capillary forces can be used to retain the fluid within the port, and a series of samples or other fluids may be introduced through a single port by sequentially blowing the fluid out through the substrate and replacing the removed fluid with an alternate fluid, or by displacing the fluid in part with additional fluid. In another aspect, microfluidic substrates have channels which varying in cross-sectional dimension so that capillary action spreads a fluid only within a limited portion of the channel network. In yet another aspect, the introduction ports may include a multiplicity of very small channels leading from the port to a fluid channel, so as to filter out particles or other contaminants which might otherwise block the channel at the junction between the channel and the introduction port.

Claims

1. A microfluidic device comprising:

a substrate having a plurality of first microfluidic channels and at least one second microfluidic channel, said plurality of first channels being in fluid communication with the at least one second channel through a respective capillary limit region, the second channel including a first end and a second end, wherein the limit regions are disposed at an end of each respective first channel and intersect the second channel between its first and second ends; and

the second channel having a cross-sectional dimension adjacent the limit regions which is larger than a cross-sectional dimension of each of the respective limit regions to inhibit wicking of fluid from the limit regions into the second channel, the first channels and the limit regions containing a polymer solution suitable for electrophoretic sample manipulation and the second channel containing a buffer fluid suitable for electroosmotic sample manipulation.

2. A microfluidic device as claimed in claim 1, wherein a minimum cross-sectional dimension of each of the limit regions is sufficiently smaller than a minimum cross-sectional dimension of the second channel such that differential capillary forces prevent fluid from wicking from the first channels through the limit regions and into the second channel when no fluid is present in the second channel.

3. A microfluidic device as claimed in claim 1, wherein the at least one second channel has at least one cross-sectional dimension of between about 0.5 and 100 microns.

4. A microfluidic device as claimed in claim 1, wherein the at least one second channel and the plurality of first channels each are about 70 microns wide and about 10 microns deep.

5. A microfluidic device as claimed in claim 1, wherein the limit regions each have a depth of about 2 microns.