Polymeric microfabricated fluidic device suitable for ultraviolet detection

• US 20040084402A1
• Filed: 03/13/2003
• Published: 05/06/2004
• Est. Priority Date: 10/05/2000
• Status: Active Grant

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Ashmead, James William, Tang, Sau Lan
• Granted Patent: US 7,150,815 B2
• Time in Patent Office: Days
• US Class Current: 216/27
• CPC Class Codes: B01L 2200/0689 Sealing
• CPC Class Codes: B01L 2200/12 Specific details about manufacturing devices
• CPC Class Codes: B01L 2300/0816 Cards, e.g. flat sample carriers usually with flow in two horizontal directions
• CPC Class Codes: B01L 2300/0887 Laminated structure
• CPC Class Codes: B01L 2300/185 using a liquid as fluid
• CPC Class Codes: B01L 2300/1894 Cooling means; Cryo cooling
• CPC Class Codes: B01L 2400/0418 electro-osmotic flow [EOF]
• 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 3/502707 characterised by the manufacture of the container or its components by shaping or joining plastic parts B29C59/00, B29C65/00; by laminating B32B37/00; manufacture of microstructural devices in general B81C
• 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 7/00 Heating or cooling apparatus autoclaves B01J3/04; Heat insulating devices
• CPC Class Codes: G01N 2021/0346 Capillary cells; Microcells
• CPC Class Codes: G01N 2030/3007 same temperature for whole column
• CPC Class Codes: G01N 21/05 Flow-through cuvettes G01N21/09 takes precedence; handling fluid samples G01N1/10
• CPC Class Codes: G01N 21/33 using ultraviolet light G01N21/39 takes precedence
• CPC Class Codes: G01N 27/44708 Cooling
• CPC Class Codes: G01N 27/44721 by optical means
• CPC Class Codes: G01N 27/44791 Microapparatus sample containers with integrated microfluidic structures B01L3/5027
• CPC Class Codes: G01N 30/6095 Micromachined or nanomachined, e.g. micro- or nanosize
• CPC Class Codes: G01N 30/74 Optical detectors measurement of intensity, velocity, spectral content, polarisation, or phase of infrared, visible or ultraviolet light G01J

Abstract

A polymer-based microfluidic device and its manufacturing methods. This microfluidic device is suitable for chromatographic and electrophoretic separations in which the detection of the components in the fluid is by means of ultraviolet (UV) spectroscopy. The device further comprises at least one cooling channel adjacent the separation channel, said cooling channel conducting a cooling fluid through the device for removing heat from the the separation channel. At least one section of the separation channel has an increased cross-sectional dimension with respect to other sections of said channel to provide an increased optical path length when the device is used in an ultraviolet detection arrangement.

Claims

1. An improved microfluidic system, comprising:

a microfluidic device which comprises a planar substrate having a first surface and a planar cover having a first surface, the first surface of the cover being bonded to the first surface of the planar substrate, at least one of the substrate or cover being substantially fabricated from a polymeric material, the device having at least first and second intersecting channels disposed therein at the interface of the bonded surfaces, the channels having interior surfaces being optionally wetted with aqueous and/or organic/aqueous buffers, and having a zeta potential associated therewith, which zeta potential is capable of supporting an electroosmotic mobility of a fluid in said channels of at least 1×

10<sup>−

5</sup> cm²V<sup>−

1</sup>s<sup>−

1</sup>, wherein said fluid is a sodium borate buffer having an ionic strength of between about 1 and about 50 millimoles (mM), and a pH of from about 7 to about 9.5, at least one of said at least first and second intersecting channels having at least one cross-sectional dimension in the range of from about 0.1 micrometer to about 1000 micrometer;

at least first, second and third ports disposed at termini of said first channel and at least one terminus of said second channel, whereby said ports are in electrical contact with the fluid in said first and second channels; and

an electrical control system for concomitantly applying a voltage at least two of said at least first, second and third ports, to selectively direct flow of the fluid in said first and second intersecting channels by electroosmotic flow,

wherein the improvement comprises the polymeric material being either a cycloolefin copolymer or an amorphous fluoropolymer.

2. The microfluidic device of the system of claim 1 wherein the interior surfaces of said channels are further modified by surface modification chemistry to achieve a zeta potential which is capable of supporting electroosmotic mobility of a fluid in said channels of up to 7×

10<sup>−

4</sup> cm²V<sup>−

1</sup>s<sup>−

1</sup>.

3. The microfluidic system of claim 1, wherein the microfluidic device comprises a 0.5 mm to 2 mm thick polymer substrate and cover which transmits at least 10% of the incident photons in the wavelength range of 240 nanometers to 350 nanometers, the substrate having micron-scale features molded on the first surface, said features comprising channels from 20 μ

m to 200 μ

m wide and 10 μ

m to 100 μ

m deep.

4. The microfluidic device of claim 3 wherein the channels are sealed by a cover that is substantially transparent to UV light.

5. The microfluidic device of the system of claim 1, wherein the polymeric material comprises a saturated co-polymer comprising polyethylene and a polycyclic olefin.

6. The microfluidic device of claim 5, wherein the polycyclic olefin is norbornene.

7. The microfluidic device of claim 3 wherein the injection molding is carried out at a resin and nozzle temperature of about 160°

C. to 200°

C. and a mold temperature of about 60°

C.

8. The microfluidic device of claim 7 wherein the surfaces of the injection-molded device are plasma treated to improve wetting properties with aqueous buffers.

9. The microfluidic device of claim 8 wherein the plasma-treated surfaces of the injection-molded device are further treated with one or more surface treatment solutions to produce a surface that may become charged when a polar buffer solution is used.

10. The microfluidic device of claim 9 wherein the surface treatment solution comprises octyltriethoxysilane.

11. The microfluidic device of the system of claim 1 wherein the polymeric material comprises a perfluorodimethyldioxole repeating unit.

12. The microfluidic device of claim 11, wherein the polymeric material is an amorphous fluoropolymer known as Teflon AF®

.

13. The microfluidic device of claim 12, the improvement further comprising spin-coating a layer of polyvinyl alcohol on at least one of the first surfaces to render the surface hydrophilic and to facilitate bonding the two first surfaces.

14. The microfluidic device of the system of claim 1, further comprising at least one cooling channel adjacent the at least first and second intersecting channels, said cooling channel conducting a cooling fluid through the device for removing heat from the at least first and second intersecting channels.

15. The microfluidic d vice of the system of claim 1, wherein at least one section of one of the at least first and second intersecting channels has an increased cross-sectional dimension with respect to other sections of said channel, to provide an increased optical path length when used in an ultraviolet detection arrangement.

16. The microfluidic device of claim 14, wherein at least one section of one of the at least first and second intersecting channels has an increased cross sectional dimension with respect to other sections of said channel, to provide an increased optical path length when used in an ultraviolet detection arrangement.