Source: https://patents.google.com/patent/US8268262B2/en
Timestamp: 2019-04-26 12:46:58+00:00

Document:
This application is a continuation of U.S. application Ser. No. 10/229,676, filed Aug. 28, 2002 now U.S. Pat. No. 6,919,058, which claims priority to U.S. Provisional Application No. 60/315,471, which was filed on Aug. 28, 2001; U.S. Provisional Application No. 60/322,621, which was filed on Sep. 17, 2001; U.S. Provisional Application No. 60/376,776, which was filed on Apr. 30, 2002; International Application PCT/SE02/00531, which was filed on Mar. 19, 2002; International Application PCT/SE02/00537, which was filed on Mar. 19, 2002; U.S. application Ser. No. 10/148,083, which is the National Stage of International Application PCT/SE02/00538 filed on Mar. 19, 2002; and U.S. application Ser. No. 10/148,084, which is the National Stage of International Application PCT/SE02/00539 filed on Mar. 19, 2002, and is a continuation-in-part of U.S. application Ser. No. 10/004,424 filed on Dec. 6, 2001, Swedish Application Nos. 0104077-3 filed Dec. 5, 2001, 0103522-9 filed on Oct. 21, 2001, and 0201310-0 filed Apr. 30, 2002 which are all incorporated herein by reference.
The microfluidic device provided in step (i) is according to the first aspect. In step (ii), at least one of the aliquots has a volume in the nano-liter range. In step (iii) two or more of the aliquots may be introduced via the same or different inlet ports. In step (iv) the driving force utilized for transport of the aliquots typically is capillary force and/or inertia force without excluding other kinds of forces as discussed elsewhere in this specification.
The invention is among others based on the recognition that the appropriate surface tension of a liquid is important for controlling a liquid flow in a microsystem. This in particular applies when dealing with aliquots in the nano-liter range and/or if the control is exerted without mechanical valves and pumps, i.e., by driving the transport of aliquots through a functional unit of the invention by capillary force and/or inertia force etc. Typical examples of inertia force are gravitational force and centrifugal force. See also under the heading “Means for driving the liquid flow”.
The microfluidic device of the present invention typically comprises one, two, three, four or more sets of microchannel structures in which aliquots are transported or processed for various purposes, for instance analytical or synthetic purposes. The prefix “micro” contemplates that an individual microchannel structure comprises one or more cavities and/or channels that have a depth and/or a width that is ≦103 μm, such as ≦102 μm. The lower limit for the width/breadth is typically significantly larger than the size of the largest reagents and constituents of aliquots that are to pass through a microchannel. The volumes of microcavities and thus also of aliquots to be transported and processed are typically ≦1000 nl, such as ≦500 nl or ≦100 nl or ≦50 nl. The nl-range comprises, if not otherwise specified, volumes <5000 nl, e.g., within the ranges specified in the preceding sentence. There may also be larger cavities, e.g., directly connected to inlet ports, with a volume within intervals, such as 1-10 μl, 1-100 μl, and 1-1000 μl (μl-range). These cavities are typically used for the introduction of samples that are to be concentrated within a microchannel structure, or of washing liquids and the like.
In the preferred variants the microchannel structures comprises inner surfaces that have been hydrophilized, for instance as described in WO 0056808. If necessary the inner surfaces may be coated with a non-ionic hydrophilic polymer as described in WO 0056808 or and U.S. Pat. No 5,773,488 (Gyros AB), for instance. The preferred variants are the same as given in these publications, e.g., to a wettability allowing for capillarity to draw a liquid into a structural unit once having passed the inlet thereof. Where appropriate hydrophobic surface breaks are introduced as outlined in WO 9958245 and WO 2002074438. See also WO 0185602 (Åmic AB & Gyros AB), which are incorporated herein by reference.
In type 3b valves, the microconduit at the position of the valve is open even if the liquid is stopped (inner valves including capillary valves, also called passive valves). Through flow in this kind of valves is accomplished simply by increasing the force driving the liquid. The use of hydrophobic surface breaks (changes in chemical surface characteristics) as valves is described in for instance WO 9958245, WO 0146465, WO 0185602 (Amic AB & Gyros AB), WO 0187486 and WO 2002074438. The use of changes in geometric surface characteristics as valves is described in for instance WO 9615576 (David Sarnoff Res. Inst.), EP 305210 (Biotrack), and WO 9807019. Type 3b valves comprise an anti-wicking function if they utilize changes in chemical and/or geometrical surface characteristics in edges as described for anti-wicking means.
Imbibing (wicking) means that liquid transport is initiated in the edges of micro channels. See for instance Dong et al (J. Coll. Interface Science 172 (1995) 278-288) and Kim et al (J. Phys. Chem. B 101 (1997) 855-863). Imbibing renders it difficult to retain a defined volume of a liquid in a desired microcavity for a longer period of time in case there is a microconduit having a length-going edge directly connected to the microcavity. This in particular applies if the volume≦5 μl, such as in the nl-range or less. If the microconduit is connected to ambient atmosphere, for instance via an inlet port, imbibing will promote evaporation and irreversible loss of a predispensed volume of a liquid.
The structural unit of the first aspect of the invention is illustrated in FIGS. 2 a-b and d-e. The unit is characterized in comprising (a) a microcavity (retaining microcavity) (219) which is intended for retaining a nl-liquid aliquot (mixed aliquot) under static non-flow conditions and is located between at least one (205,215,237) of said one or more inlet ports (205,215,237) and at least one (238,241) of said one or more outlet ports (207,238,239,240,241); (b) a mixing unit (302+303+30i) which is located upstream the retaining microcavity (219) and downstream said at least one inlet port (205,215,237) and in which two or more aliquots (aliquot 1, aliquot 2 etc.) are to be mixed to form said mixed aliquot; and (c) two or more microconduits (218,220,242) directly connected to the retaining microcavity (219) and communicating with one of said inlet or outlet ports (205,207,215,237,238, 239,240,241).
The retaining microcavity (219) may have different forms as known in the field. Preferred variants often define or are part of a U/Y-shaped structures, possibly linked to upwardly bent microconduits at either one or both of the upwardly directed shanks of the U/Y as described previously for reaction microcavities (WO 0040750, WO 0146465). The U-shaped structure may also be as presented in FIG. 2 e where the U is defined by a reaction microcavity which comprises two upwardly directed shanks, the upper parts of which are connected to microconduits (218,220) containing the anti-wicking means/valves (221 e,a). Microconduit (218) plus the most downstream part of the retaining microcavity (219) define an upward bent that will provide a valve function. This latter variant may be advantageous in the case the mixed aliquot is to be transported further downstream in the structure. See FIG. 2 a-b and e. Another variant is that the microcavity (219) is circle like with the down stream or upstream microconduit attached without formation of this kind of bent. See for instance FIG. 2 e in which one of the microconduits (242) is a pure air channel which preferably has an hydrophobic inner surface that in fact creates an anti-wicking effects and renders passage of liquids difficult.
The inlet arrangement may comprise a common inlet microconduit (not shown) for several aliquots and/or separate inlet microconduits (224 and 225) for individual aliquots. The joint between these microconduits and the inlet openings are preferably located at the upper part of precollecting microcavity (203). In the upstream direction each of these inlet microconduits (224 and 225) communicates with an inlet port (205 and 215). Each inlet microconduit (224 and 225) may comprise a submicrocavity permitting separate predispensing of an aliquot to a microchannel structure before transport down into the microcavity (203). In FIGS. 2 a-b one of these submicrocavities is microcavity (226) of the volume-defining unit (213) and the other Y-shaped structure (227) a part of which belongs to the common distribution channel (204). Between each submicrocavity (226,227) and microcavity (203) there may be a valve function (221 d,c, respectively) that enables for aliquots to be transported into the submicrocavities (226,227) without leakage into the microcavity (203). The valve function at these positions is preferably an inner valve of the same kind as discussed for the valve functions (221 a,b) associated with the mixing microconduit (202), e.g., a surface break (non-wettable) (221 a,b).
Based on FIGS. 3 a-b, the unit comprises: (a) a continuous microconduit (301) containing an upper part at each end (end parts, 302, 303) and therebetween alternating lower and upper parts (304 a-h/f and 305 a-e, respectively); (b) the number of upper parts including the end parts is n and the number of lower parts is n-1 where n is an integer >2, i.e., ≧3; (c) each of the upper parts (302, 303, 305 a-e/g) has means for venting (top vent, inlet vents) (306 a-g/i) to ambient atmosphere and/or anti-wicking means (326 a-i) in length-going edges delineating its lower wall(s); (d) each of the lower parts (304 a-f/h) has an emptying opening which in a downstream direction via a connecting microconduit (307 a-f/h) communicates with a substructure of a microchannel structure and/or with a corresponding substructure of another microchannel structure; (e) each of the connecting microconduits (307 a-f/h) has a valve (308 a-f/h), i.e., a valve function in close association with the joint between the connecting microconduit and the corresponding lower part; (f) an inlet port (309) is connected to the continuous microconduit (301) directly or indirectly at one of the upper parts (302, 303, 305 a-e/g), preferably via one of the end parts (302 or 303); and (g) an outlet port (310) is connected to the continuous microconduit (301) directly or indirectly at another upper part (302, 303, 305 a-e/g), preferably via one of the end parts (302 or 303) (which preferably is not connected to the inlet port, i.e., an inlet port and an outlet port should not connected at the same upper part).
The integer n is preferably ≧2, such as 3, 4, 5, 7, 8, 9, 10, 11, 12 or more.
Unit C is intended for distributing (n-1) aliquots to (n-1) microchannel structures or (n-1) part structures of a microchannel structure. The volume between two close top vents (306 a-e/g) will in most variants define the volume of the aliquot to be dispensed through the connecting microconduit (307 a-f/h) between these top vents (segment). By varying the depth and/or width of different segments, one can envisage that the volumes dispensed through different connecting microconduits (307 a-f/h) can differ in a controlled manner.
When the desired number of segments has been filled a downwardly directed driving force is applied to pass the aliquots through their respective connecting microconduit/valve (307 a-c /308 a-c ).
The cross-sectional area (a,) in the volume-defining microcavity (501) at the overflow opening is in preferred variants smaller than the largest cross-sectional area (a2) between the overflow opening and the outlet opening (506). The ratio a1/a2 typically is ≦1/3, such as ≦1/10. This means a significant constriction of the microcavity (501) at the joint between the overflow microconduit (504) and the microcavity (501), i.e., at the joint between inlet microconduit (502) and volume-defining microcavity (501).
A microchannel structure comprising unit E may in its preferred variants be equipped with valve functions (506, 508), preferable inner valves of the non-closing type, and be present on a spinnable substrate as discussed elsewhere in this specification. If the intention is to drive the liquid out of the overflow channel (504) before the metered aliquot is released via the outlet microconduit (503), it becomes important to have a sufficiently large difference in radial distance (r1) between the overflow opening in the volume-defining microcavity (501) and the ending (512) of the overflow microconduit (504) in a waste chamber (511) relative to the difference (r2) in radial distance between the overflow opening and the valve (506) in the outlet microconduit (503). r1 shall be essentially larger than r2. This particularly applies if the valve function (506) in the outlet microconduit (503) is an inner non-closing valve. By properly selecting r1≧r2 , e.g., r1≧1.25r2, or r1≧1.5r2, or r1≧2r2, or r1≧5r2, or r1≧10r2, it will be possible for the liquid in the over-flow microconduit to pass through the valve (508) at a lower driving force (e.g., lower spinning speed) than required for the liquid in the volume-defining microcavity to pass through the valve (506). The optimal relation between the two distances depends on various factors, such as width, breadth, wettability, roughness etc. of the microconduits concerned as well as surface tension, density et of the liquid concerned.
wherein the inner surfaces of the mixing microconduit have a wettability permitting capillary force to draw liquid into the unit once the liquid has passed the entrance of the unit.
2. The microfluidic device of claim 1, wherein the outlet opening is in the lower part of the microcavity.
3. The microfluidic device of claim 1, wherein the inlet arrangement is connected to the upper or lower part of the microcavity.
4. The microfluidic device of claim 1, wherein the inlet arrangement comprises a common inlet microconduit for several of the aliquots and/or separate inlet microconduits for individual liquid aliquots.
5. The microfluidic device of claim 4, wherein at least one inlet microconduit comprises a submicrocavity that is part of a volume-defining unit.
6. The microfluidic device of claim 5 further comprising a valve between the submicrocavity in each inlet microconduit and the microcavity.
7. The microfluidic device of claim 6, wherein the valve is an inner valve.
8. The microfluidic device of claim 6, wherein the valve is a capillary valve.
9. The microfluidic device of claim 6, wherein the valve is a capillary valve comprising a hydrophobic surface break.
10. The microfluidic device of claim 6, wherein the device comprises two or more of the microchannel structure and the submicrocavity in one inlet microconduit is part of a distribution channel that is common for several of the microchannel structures of said two or more microchannel structures.
11. The microfluidic device of claim 1, wherein the microfluidic device is in the form of a disc and comprises two or more of the microchannel structure.
12. The microfluidic device of claim 1, wherein the microchannel structure is oriented from an inner position to an outer position relative to a spin axis enabling centrifugal force created by spinning the device about the spin axis to drive liquid placed in the microchannel structure through at least a part of the microchannel structure.
13. The microfluidic device of claim 5, wherein the submicrocavity has a volume≦5,000 nl.
14. The microfluidic device of claim 5, wherein the submicrocavity has a volume≦100 μl.
15. The microfluidic device of claim 1, wherein the mixing microconduit comprises a chain of interlinked microcavities.
16. The microfluidic device of claim 1, wherein the mixing microconduit repeatedly curves in alternate directions and has substantially constant width.
17. The microfluidic device of claim 1, wherein the mixing microconduit comprises at least one cavity in which the cross-sectional area increases from the inlet, reaches a maximum and then decreases towards the outlet, with a steeper increase from the middle to the outlet than from the inlet to the middle.
further comprising a valve between the submicrocavity in each inlet microconduit and the microcavity.
21. The microfluidic device of claim 20, wherein the valve is an inner valve.
22. The microfluidic device of claim 21, wherein the valve is a capillary valve.
23. The microfluidic device of claim 21, wherein the valve is a capillary valve comprising a hydrophobic surface break.
Communication pursuant to Article 94(3) EPC issued Jul. 23, 2009 during the prosecution of European Application No. 02 763 153.0-2113.
Definition of "Configure"; http://dictionary.cambridge.org/dictionary/british/configure (Internet).
Extended European Search Report issued in European Application No. 10184014.8, mailed Dec. 2, 2010.
Extended European Search Report issued in European Application No. 10184038.7, mailed Dec. 23, 2010.
High-Throughput SNP Scoring in a Disposable Microfabricated CD Device; Presented at HGM 2000, Vancover, Canada, Apr. 9-12, 2000.
Kim et al, J. Phys. Chem B 101 (1997), pp. 855-863.
U.S. Appl. No. 09/674,457, filed Jan. 5, 2001.
U.S. Appl. No. 09/830,475, filed Sep. 24, 2001.
U.S. Appl. No. 09/869,554, filed Jun. 28, 2001.
U.S. Appl. No. 09/958,577, filed Nov. 29, 2001.
U.S. Appl. No. 10/070,912, filed Mar. 13, 2002.
U.S. Appl. No. 10/129,032, filed Apr. 29, 2002.

References: Application No. 60
 Application No. 60
 Application No. 60
 Application No. 02
 Application No. 10184014
 Application No. 10184038