In situ micromachined mixer for microfluidic analytical systems

• US 6,170,981 B1
• Filed: 05/06/1999
• Issued: 01/09/2001
• Est. Priority Date: 05/07/1998
• Status: Expired due to Fees

• Current Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: He, Bing, Regnier, Fred
• Primary Examiner(s): Cooley, Charles E.
• Application Number:
  US09/306,547
• Time in Patent Office: 614 Days
• Field of Search: 366/181.5, 366/181.6, 366/336, 366/337, 366/340, 481/894, 138/37, 138/39
• US Class Current: 366/336
• CPC Class Codes: B01F 2101/23 Mixing of laboratory samples e.g. in preparation of analysing or testing properties of materials
• CPC Class Codes: B01F 25/43231 the channels or tubes crossing each other several times
• CPC Class Codes: B01F 33/30 Micromixers
• CPC Class Codes: B01F 33/3039 with mixing achieved by diffusion between layers
• CPC Class Codes: B01L 2300/0867 Multiple inlets and one sample wells, e.g. mixing, dilution
• CPC Class Codes: B01L 2400/0421 electrophoretic flow
• 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 3/502746 characterised by the means for controlling flow resistance, e.g. flow controllers, baffles B01L3/502738 takes precedence
• CPC Class Codes: G01N 2030/347 mixers
• CPC Class Codes: Y10S 366/03 Micromixers: variable geometry from the pathway influences mixing/agitation of non-laminar fluid flow

Abstract

The present invention relates to an in situ micromachined mixer for microfluidic analytical systems. In a preferred embodiment, a 100 pL mixer for liquids transported by electroosmotic flow (EOF) is described. Mixing was achieved in multiple intersecting channels with a bimodal width distribution and varying lengths. Five μm width channels ran parallel to the direction of flow whereas larger 27 μm width channels ran back and forth through the network at a 45° angle. All channels were approximately 10 μm deep. It was observed that little mixing of confluent streams occurred in the 100 μm wide mixer inlet channel where mixing would be achieved almost exclusively by diffusion. In contrast, mixing was complete after passage through the channel network in the ≈200 μm length mixer. Solvent composition was altered by varying the voltage on solvent reservoirs. The high efficiency attained in this mixer was attributed to the presence of a 2 pL vortex in the center of the mixer. Video tracking of fluorescent particles with a fluorescence microscope allowed the position and volume of this vortex to be determined.

Claims

1. A microfluidic mixer, comprising:

an inlet;

an outlet, wherein the inlet and the outlet define a flow axis extending therebetween;

a first flow channel extending between the inlet and the outlet, wherein the first flow channel includes a first section oriented at an obtuse angle to the flow axis and a second section oriented at an acute angle to the flow axis, thereby defining a substantially triangular region bounded on two sides by the first and second sections;

a plurality of second flow channels disposed in the substantially triangular region, each of said second flow channels allowing fluid flow between the first and second sections substantially parallel to the flow axis.

2. The microfluidic mixer of claim 1, wherein the first flow channel has a substantially larger cross-sectional area than each of the second flow channels.

3. The microfluidic mixer of claim 2, wherein the first flow channel cross-sectional area is approximately five times larger than each of the second flow channel cross-sectional areas.

4. The microfluidic mixer of claim 1, wherein the first section is oriented at a substantially 135°

angle to the flow axis, and the second section is oriented at a substantially 45°

angle to the flow axis.

5. The microfluidic mixer of claim 1, wherein each of the plurality of second flow channels are of a different length.

6. The microfluidic mixer of claim 1, wherein the first flow channel and each of the second flow channels are formed in a quartz substrate.