Method of forming a multi-layer microfluidic device

ABSTRACT

A method is provided for fabricating a multi-layer microfluidic device on a base. A first layer is positioned on the base in a spaced relationship thereto so as to define a construction cavity therebetween. The first layer has a passageway therethrough which communicates with the construction cavity. A mask is positioned between the construction cavity and an ultraviolet source. The mask corresponds to a channel to be formed in the construction cavity. The construction cavity is filled with material and a portion of the material is polymerized within the construction cavity so as to solidify the same. The solidified material defines the channel. Thereafter, the material is flushed from the channel in the construction cavity.

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIGS. 22-25, a microfluidic device constructed in accordance with the methodology of the present invention is generally designated by the reference numeral . It is intended that microfluidic device include a plurality of layers, each of which incorporating a corresponding channel network, as hereinafter described. Referring to FIGS. 1-2, microfluidic device includes a first layer positioned on upper surface of microscope slide . In addition to being positionable on microscope slide , first layer may be positioned on any substrate, such as a silicon wafer or print circuited board, without deviating from the scope of the present invention in order to allow microfluidic device to be operatively connected to such substrate if so desired by the user. First layer is formed from a polymeric material and includes upper and lower surfaces and , respectively, interconnected by first and second ends and , respectively, and first and second sides and , respectively. A plurality of holes -extend through first layer and communicate with upper and lower surfaces and , respectively, thereof.

Gasket includes an upper surface affixed to lower surface of first layer adjacent the outer periphery thereof. Lower surface of gasket is affixed to upper surface of microscope slide . As assembled, inner surface of gasket , lower surface of first layer and upper surface of microscope slide define a cavity for receiving polymerizable material therein, FIG. . The material is injected into cavity through any one of the openings -through the first layer .

Referring to FIGS. 4-8, optical mask is affixed to upper surface of first layer . It is intended that optical mask correspond to the shape of a channel network to be formed in cavity , FIG. 9, as hereinafter described. By way of example, optical mask is generally Y-shaped and includes a base portion having first and second legs and , respectively, diverging from first end thereof. Terminal ends , and of optical mask overlap corresponding openings , , and , respectively, in first layer in order for such opening to remain open after polymerization of material , as hereinafter described.

Referring to FIGS. 6 and 7, ultraviolet light generally designated by the reference numbers is generated by a UV source , and is directed towards microfluidic device at an angle generally perpendicular to upper surface of first layer . As is known, the polymerizable material polymerizes and solidifies when exposed to ultraviolet light . It can be appreciated that optical mask shields a first portion of the polymerizable material from ultraviolet light . As a result, second portion of material , which is exposed to ultraviolet light , polymerizes and solidifies. On the other hand, first portion of material , which is not exposed to ultraviolet light , does not polymerize and remains in a fluidic state.

Referring to FIGS. 8 and 9, after polymerization of second portion of material by ultraviolet light , optical mask is removed from upper surface . In addition, the non-polymerized portion of the material is flushed from channel network and openings , and in first layer . It can be appreciated that channel network has a generally Y-shape that corresponds to the shape of optical mask . Channel network includes a base having first and second legs and diverging from a first end thereof. Terminal end of leg of channel network communicates with opening through first layer . Terminal end of leg of channel network communicates with opening through first layer . Terminal end of base of channel network communicates with opening through first layer .

Referring to FIG. 10, in order to form a multi-layer microfluidic device, second layer is positioned on upper surface of first layer . It can be appreciated that second layer is identical in structure to first layer , and as such, the previous description of first layer is understood to describe second layer as if fully described herein. In order to facilitate understanding, common reference characters are used hereinafter to refer to the components of first layer and second layer .

Referring to FIGS. 11-14, second layer is positioned on first layer such that inner surface of gasket of second layer , lower surface of second layer and upper surface of first layer define a cavity for receiving additional polymerizable material , as hereinafter described. In addition, second layer is positioned on upper surface of first layer such that openings , and through second layer are aligned with corresponding openings , , and , respectively, through first layer .

In order to insure communication between channel network and the environment outside microfluidic device , a plurality of plugs are inserted into microfluidic device . Plugs may take the form of physical plugs, immiscible fluid, dissoluble solid or any other appropriate material. Plug is inserted through opening in second layer , cavity , opening in first layer and into channel network . Plug is inserted through opening in second layer , cavity , opening through first layer and into channel network . Plug is inserted through opening in second layer , cavity , opening in first layer and into channel network . Thereafter, polymerizable material is injected into cavity through one or more of openings , and through second layer , FIG. . It can be appreciated that plugs , and isolate channel network and prevent material from flowing therein.

Referring to FIGS. 15-18, second optical mask is affixed to upper surface of second layer . By way of example, second optical mask includes a first masking portion having a first end which overlaps opening through second layer and a second end which extends about the outer periphery of plug . In addition, second optical mask includes a second masking portion having a first end overlapping opening through second layer and a second end which extends about plug . It is intended that second optical mask correspond to the configuration of a second channel network , FIG. 20, to be formed in a microfluidic device .

After second optical mask is affixed to upper surface of second layer , ultraviolet light is directed towards microfluidic device at an angle generally perpendicular to upper surface of second layer . It can be appreciated that upper mask shields a first portion of material within cavity from ultraviolet light . Consequently, ultraviolet light polymerizes and solidifies only second portion of material within cavity which is not overlapped by second optical mask . Portion of material in cavity which is overlapped by a second optical mask is not polymerized, and as such, remains fluidic. Thereafter, as best seen in FIG. 19, second optical mask is removed from upper surface of second layer and the non-polymerized portion of material is flushed from second channel network formed in microfluidic device . In addition, plugs are removed from microfluidic device .

Referring to FIGS. 20 and 21, second channel network includes first and second generally parallel channels and , respectively. First channel of second channel network has a first end which communicates with opening in second layer such that opening through second layer defines a first input to microfluidic device , FIG. . Second end of first channel of second channel network communicates with first channel network through opening in first layer . In addition, first channel communicates with upper surface of second layer through opening in second layer , FIG. .

First end of second channel of second channel network communicates with opening through second layer such that opening defines a second input to microfluidic device , FIG. . Second end of second channel of second channel network communicates with first channel network through opening through first layer , FIG. . In addition, second end of second channel of second channel network communicates with upper surface of second layer through opening in second layer , FIG. .

Referring to FIGS. 23 and 24, first channel network also communicates with upper surface of second layer through opening through: first layer ; a passageway through polymerized portion of material within cavity formed by the presence of plug extending through cavities during polymerization; and cavity through second layer such that opening through second layer corresponds to an output for microfluidic device . It is contemplated to provide caps and on upper surface of second layer to close openings and in second layer so as to isolate first and second channel networks and , respectively, from the environment external of microfluidic device .

As described, a sample fluid under pressure may be provided at inputs and of second layer of microfluidic device . The sample fluid will flow through channels and of second channel network and into first channel network through corresponding openings and , respectively, in first layer . The sample fluid flow will continue to through channel network and out of microfluidic device through output through second layer .

It can be appreciated that channel networks having different configurations may be fabricated within microfluidic device using the method heretofore described by simply varying the configurations of optical masks and . In addition, it is contemplated as being within the scope of the present invention to provide microfluidic device with additional layers and to form additional channel networks using the methodology heretofore described. No limit as to the number of layers is contemplated. In such microfluidic devices having three more layers, it can be appreciate that the channel networks formed by adjacent layers do not necessarily have to be in communication with each other.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings furnished herewith illustrate a preferred methodology of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the following description of the illustrated embodiment.

In the drawings:

FIG. 1 is a top plan view of a first layer of a microfluidic device to be constructed in accordance with the present invention;

FIG. 2 is a cross-sectional view of the first layer of the microfluidic device taken along line — of FIG. 1;

FIG. 3 is a cross-sectional view similar to FIG. 2, showing a cavity defined by the first layer of the microfluidic device filled with a polymerizable material;

FIG. 4 is a top plan view of the first layer of the microfluidic device with a optical mask positioned thereon;

FIG. 5 is a cross-sectional view of the first layer of the microfluidic device taken along line — of FIG. 4;

FIG. 6 is a top plan view of the first layer of the microfluidic device after the polymerization thereof;

FIG. 7 is a cross-sectional view of the first layer of the microfluidic device taken along line — of FIG. 6;

FIG. 8 is a cross-sectional view of the first layer of the microfluidic device after flushing of the polymerizable material from the channel network thereof;

FIG. 9 is a cross-sectional view of the first layer of the microfluidic device taken along line — of FIG. 8;

FIG. 10 is an expanded, isometric view showing assembly of the microfluidic device;

FIG. 11 is a cross-sectional view of the microfluidic device taken along line — of FIG. 10;

FIG. 12 is a cross-sectional view of the microfluidic device, similar to FIG. 11, showing plugs positioned within user selected openings in the microfluidic device;

FIG. 13 is a cross-sectional view of a microfluidic device of the present invention, similar to FIG. 12, showing a cavity, defined by a second layer of the microfluidic device filled with polymerizable material;

FIG. 14 is a top plan view of the microfluidic device of FIG. 13;

FIG. 15 is a top plan view of the microfluidic device having an optical mask affixed to the upper surface of the second layer thereof;

FIG. 16 is a cross-sectional view of the microfluidic device taken along line — of FIG. 15;

FIG. 17 is a cross-sectional view of the microfluidic device taken along line — of FIG. 15;

FIG. 18 is a cross-sectional view of the microfluidic device similar to FIG. 17, showing polymerization of the microfluidic device with UV light;

FIG. 19 is a cross-sectional view of the microfluidic device similar to FIG. 18, showing the non-polymerized material flushed from the channel network defined by the second layer thereof;

FIG. 20 is a cross-sectional view of the microfluidic device taken along line — of FIG. 19;

FIG. 21 is a top plan view of the microfluidic device;

FIG. 22 is a cross-sectional view of the microfluidic device taken along line — of FIG. 21;

FIG. 23 is a cross-sectional view of the microfluidic device taken along line — of FIG. 21;

FIG. 24 is a cross-sectional view of the microfluidic device taken along line — of FIG. 21; and

FIG. 25 is a cross-sectional view of the microfluidic device taken along line — of FIG. .

REFERENCE TO GOVERNMENT GRANT

This invention was made with United States government support awarded by the following agencies: DOD ARPA F30602-00-0570. The United States has certain rights in this invention.

CLAIMS

1. A method of forming a microfluidic device on a base having an upper surface, comprising the steps of: providing a first layer having upper and lower surfaces and being in a spaced relationship to the upper surface of the base such that the lower surface of the first layer and the upper surface of the base define a first construction cavity therebetween, the first layer has passageway therethrough which communicates with the first construction cavity; positioning a mask between the first construction cavity and a source, the mask corresponding to a first channel to be formed in the first construction cavity; filling the first construction cavity with a material; polymerizing a portion of the material within the first construction cavity outside the first channel with the source such that the portion of the material is solidified; flushing the material from the first channel; providing a second layer having upper and lower surfaces and being in a spaced relationship to the first layer such that the lower surface of the second layer and the upper surface of the first layer define a second construction cavity, therebetween, the second layer having a passageway therethrough which communicates with the second construction cavity; positioning a second mask between the second construction cavity and the source, the second mask corresponding to a second channel to be formed in the second construction cavity; filling the second construction cavity with the material; polymerizing a portion of the material within the second construction cavity outside the second channel with the source such that the portion of the material is solidified; and flushing the material from the second channel in the second construction cavity, and interconnecting the second channel with the first channel.

2. The method of claim 1 wherein the first layer includes a fill hole therethough for allowing for the filling of the first construction cavity therethrough.

3. The method of claim 1 wherein the first layer has a passageway therethrough which communicates with the first construction cavity and wherein the passageway communicates with the first channel in the construction cavity and wherein the method further comprises the additional step of plugging the passageway in the first layer to prevent the material from flowing therein during filling.

4. The method of claim 1 further comprising the additional step of positioning a gasket about the first construction cavity to maintain the material therein during filling.

5. The method of claim 1 wherein the step of positioning the mask includes the step of affixing the mask to the upper surface of the first layer.

6. The method of claim 1 wherein: the first layer has a passageway therethrough which communicates with the construction cavity; the second layer has a passageway therethrough which communicates with the second construction cavity; and the passageway through the second layer and the passageway through the first layer are axially aligned and communicate with each other through the second channel in the second construction cavity.

7. The method of claim 6 comprising the additional steps of: plugging the passageways in the first and second layers to prevent the material from flowing therein during the step of filling of the second construction cavity with the material; and clearing the passageways in the first and second layers after the step of polymerizing a portion of the material within the second construction cavity such that the first channel in the first construction cavity and the second channel in the second construction cavity communicate through the passageway in the first layer.

8. The method of claim 7 wherein the passageway through the second layer communicates with the upper surface of the second layer through an opening and wherein the method further comprises the additional step of covering the opening.

9. The method of claim 1 comprising the additional step of removing the mask between the first construction cavity and the source prior to providing the second layer.

10. The method of claim 1 wherein: the first layer has a passageway therethrough which communicates with the first construction cavity, the passageway in the first layer communicates with the first channel in the first construction cavity and with the second channel in the second construction cavity; the first layer includes a second passageway therethrough that communicates with the first channel in the first construction cavity; the passageway in the second layer communicates with the second channel in the second construction cavity and with the upper surface of the second layer through a first opening; and the second layer includes a second passageway therethrough that communicates with the second passageway through the first layer and with the upper surface of the second layer through a second opening, such that one of the openings in the second layer comprises an input and the other of the openings comprises an output.

11. A method of forming a microfluidic device on a base having an upper surface, comprising the steps of: providing a first layer having upper and lower surfaces and being in a spaced relationship to the upper surface of the base such that the lower surface of the first layer and the upper surface of the base define a first construction cavity therebetween; filling the first construction cavity with a material; polymerizing a portion of the material within the first construction cavity so as to solidify the same, the solidified material defining a first channel; providing a second layer having upper and lower surfaces and being in a spaced relationship to the first layer such that the lower surface of the second layer and the upper surface of the first layer define a second construction cavity therebetween; filling the second construction cavity with the material; polymerizing a portion of the material within the second construction cavity so as to solidify the same, the solidified material defining a second channel; and interconnecting the first and second channels.

12. The method of claim 11 comprising the additional step of flushing the material from the first channel.

13. The method of claim 11 wherein the step of polymerizing a portion of the material includes the steps of: positioning a mask between the first construction cavity and a source, the mask corresponding to the first channel formed in the first construction cavity; and generating ultraviolet radiation with the source.

14. The method of claim 11 comprising the additional steps: providing a first passageway through the first layer, the first passageway communicating with the first and second channels; providing a second passageway through the first layer, the second passageway communicating with the first channel, providing a first passageway through the second layer, the first passageway through the second layer communicating with the second channel and with the upper surface of the second layer through a first opening; and providing a second passageway through the second layer, the second passageway through the second layer communicating with the second passageway through the first layer and with the upper surface of the second layer through a second opening.

15. The method of claim 14 wherein one of the openings in the second layer comprises an input and the other of the openings comprises an output.

16. A method of forming a microfluidic device on a base having an upper surface, comprising the steps of: providing a first layer having upper and lower surfaces and being in a spaced relationship to the upper surface of the base such that the lower surface of the first layer and the upper surface of the base define a construction cavity therebetween, the first layer having first and second passageways and a fill hole therethrough which communicate with the construction cavity; affixing a mask to the upper surface of the first layer corresponding to a channel network to be formed in the construction cavity; injecting a material into the construction cavity through the fill hole in the first layer; polymerizing a portion of the material within the construction cavity so as to solidify the same, the solidified material defining the channel network that communicates with the first and second passageways through the first layer; flushing the material from the channel network; removing the mask from the upper surface of the first layer; providing a second layer having upper and lower surfaces and being in a spaced relationship to the upper surface of the first layer such that the lower surface of the second layer and the upper surface of the first layer define a second construction cavity therebetween, the second layer having first and second passageways and a fill hole therethrough which communicate with the second construction cavity; plugging the first and second passageways in the first layer; affixing a mask to the upper surface of the second layer corresponding to a second channel network to be formed in the second construction cavity; injecting a material into the second construction cavity through the fill hole in the second layer; polymerizing a portion of the material within the second construction cavity so as to solidify the same, the solidified material in the second construction cavity defining the second channel network that communicates with the first passageway through the second layer; flushing the material from the second channel network; unplugging the first and second passageways in the first layer such that the first passageway through the first layer communicates with the second channel network and the second passageway in the first layer communicates with the second passageway through the second layer; and removing the mask from the upper surface of the second layer.

17. The method of claim 16 further comprising the additional steps of: positioning a first gasket about the construction cavity to maintain the material therein during the filling thereof; and positioning a second gasket about the second construction cavity to maintain the material therein during the filling thereof.

18. The method of claim 16 wherein: the first passageway through the second layer communicates the upper surface of the second layer through a first opening; the second passageway through the second layer communicates the upper surface of the second layer through a second opening; and wherein the method comprises the additional step of: providing one of the openings in the second layer as an input and the other of the openings in the second layer as an output.

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