Fluidics device, apparatus, and method for partitioning fluid

Abstract

Embodiments of the invention relate to centrifugal fluidic devices, apparatus, and methods. Embodiments disclosed are fluidic devices, and associated apparatus and methods, which can partition a fluid sample from a single inlet or plurality of inlets into a plurality of chambers via their fluid inlets. Each chamber possesses a fluid outlet and a gas outlet. Partitioned fluid can be further distributed under centrifugal pressure to downstream fluidics modules, permitting various multiplexed assays to be performed including nucleic acid amplification tests.

Claims

1. A fluidic device (21) which is rotatable about a rotational center (19), comprising: one or a plurality of first fluid inlets (1); one or a plurality of first chambers (3) located farther from the rotational center (19) than any first fluid inlets (1), with each first chamber (3) having a fluid outlet (50), a gas outlet (51), and a fluid inlet (49); and one or a plurality of first channels (2), wherein each first channel (2) fluidly connects a first chamber's fluid inlet (49) to a first fluid inlet or first fluid inlets (1), wherein each first chamber (3) has a fluid outlet (50) which is located farther from the rotational center (19) than either the first chamber's fluid inlet (49) or the first chamber's gas outlet (51), wherein the first chamber's fluid outlet (50) has a higher resistance to fluid flow than the first chamber's gas outlet (51), wherein the first chamber's gas outlet (51) has a higher resistance to fluid flow than the first chamber's fluid inlet (49), and wherein, with input of fluid into the first fluid inlet or inlets (1), fluid is motivated through the first channel or channels (2) into each first chamber (3) via its fluid inlet (49), filling each first chamber (3) while not moving past the first chamber's fluid outlet (50) or gas outlet (51).

2. The fluidic device (21) as in claim 1, wherein for each first chamber (3) the cross-sectional area of the first chamber's fluid inlet (49) is greater than the cross-sectional area of the first chamber's gas outlet (51), which in turn is greater than the cross-sectional area of the first chamber's fluid outlet (50).

3. The fluidic device (21) as in claim 1, wherein the first chamber's fluid outlet (50) is closer to the first chamber's fluid inlet (49) than the first chamber's gas outlet (51) is to the first chamber's fluid inlet (49).

4. The fluidic device (21) as in claim 1, wherein the first chamber's fluid outlet (50) connects to a second channel (5), wherein the second channel (5) is a fluidic valve which is fluidly connected to a third channel (6), wherein the third channel (6) follows a route which moves further from the rotational center (19) as it progresses azimuthally with respect to the rotational center (19), is lined on its radially distal side with respect to the rotational center (19) by a plurality of second chambers (7) to which it is fluidly connected, and terminates in a third chamber (13), wherein the second chambers (7) are terminated at their radially distal portions with respect to the rotational center (19) by a fourth channel (8), wherein said fourth channel (8) is a fluidic valve which connects each second chamber (7) to a separate fourth chamber (9), which is located further from the rotational center than the second chamber (7), and wherein each fourth chamber (9) has a gas outlet (24) which is located on its radially proximal side with respect to the rotational center (19).

5. The fluidic device (21) as in claim 1, wherein at least one indentation (20) is present along the edge of the device.

6. An apparatus for partitioning fluid, comprising: a fluidic device (21) as described in claim 1; and a means of rotating the fluidic device.

7. The apparatus as described in claim 6, wherein the means of rotating the fluidic device is a motor (26).

8. The apparatus as described in claim 7, wherein the motor (26) is attached to a rotor (25) and is controlled by a means for modulating rotational frequency.

9. The apparatus as described in claim 8, wherein the rotor (25) has at least one protuberance (30) which can mechanically engage with at least one indentation (20) present along the edge of the fluidic device (21).

10. A method for partitioning fluid, comprising: introducing a fluid into a fluidic device (21) through one or more fluid first fluid inlets (1); applying pressure to motivate fluid from the first fluid inlet or inlets (1) into one or more first channels (2); continuing to apply pressure to motivate fluid from a first channel (2) into a first chamber (3) via its fluid inlet (49), until fluid has reached both the first chamber's fluid outlet (50) and gas outlet (51); continuing to apply pressure such that fluid is motivated through the first fluid inlet or inlets (1) into another first channel (2) and into the first chamber (3) with which it is fluidly connected; continuing to apply pressure until each first chamber (3) has liquid reaching its fluid outlet (50) and gas outlet (51); and rotating the fluidic device (21) at a first rotational frequency which can generate a sufficient centrifugal force such that the fluid in each first chamber (3) is motivated radially outwards through the first chamber's fluid outlet (50) and away from the first chamber's fluid inlet (49) and gas outlet (51).

11. The method for partitioning fluid as in claim 10, further comprising: rotating the fluidic device (21) at the first rotational frequency to generate a sufficient centrifugal force such that the fluid in each first chamber (3) is motivated through the first chamber's fluid outlet (50), through a second channel (5) which functions as a fluidic valve, into a third channel (6), and into a plurality of second chambers (7) such that each second chamber (7) is filled up to a fourth channel (8) which terminates its radially distal portion with respect to the rotational center (19), with excess fluid beyond what can fill the second chambers (7) proceeding further along the second channel (6) until reaching a third chamber (13); and rotating the fluidic device (21) at a second rotational frequency which is higher than the first rotational frequency and generates a sufficient centrifugal force such that the fluid in each second chamber (7) is motivated through the fourth channel (8) which functions as a fluidic valve into a separate fourth chamber (9), with fluid displacing any gas present in the fourth chamber (9) via its gas outlet (24).

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0044] FIG. 1 is a layout view of a centrifugal fluidic device.

[0045] FIG. 2 is a perspective view of said centrifugal fluidic device.

[0046] FIG. 3 is a perspective view of said centrifugal fluidic device along with the apparatus for actuating the fluidic device.

[0047] FIG. 4A, FIG. 4B, and FIG. 4C depict the filling of the central chambers of said centrifugal fluidic device.

[0048] FIG. 5A, FIG. 5B, and FIG. 5C depict distribution of fluid from the central chambers within said centrifugal microfluidic device to downstream fluidics modules.

[0049] FIG. 6A, FIG. 6B, and FIG. 6C depict partitioning of fluid into reaction chambers within said centrifugal microfluidic device.

[0050] FIG. 7 is a layout view of an alternative embodiment of the centrifugal fluidic device.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0051] Embodiments of the invention are intended to partition fluids. To this end, there is a plurality of suitable methods and materials which can be used to produce embodiments of the invention. These materials and methods, along with any surface coatings or device treatments implemented, can be selected to suit a variety of applications, including but not limited to chemical and biological experiments or assays, and medical diagnostics.

[0052] Embodiments of the invention can be manufactured as two separate halves of a single centrifugal fluidic device bisected by a plane which is coplanar with the plane of rotation of the device. These halves can be joined together, which allows for the loading of reagents or assay materials into the centrifugal fluidic device prior to assembly of the centrifugal fluidic device. These halves do not need to be made from the same material, and can be made from a variety of materials as are suitable to the intended applications of the centrifugal fluidic devices. Selection of these materials is therefore dependent upon manufacturing techniques, structural specifications, and reagent compatibility, amongst other parameters. Materials which can be used in exemplary embodiments include but are not limited to: polystyrene, polypropylene, polycarbonate, polyethylene, and Acrylonitrile Butadiene Styrene (ABS), glass, polydimethylsiloxane (PDMS), silicon, silica, and quartz. Depending upon choice of materials, centrifugal fluidic device halves can be produced, for example, using injection molding with suitable materials, including but not limited to polystyrene, polypropylene, polycarbonate, polyethylene, and Acrylonitrile Butadiene Styrene (ABS). These halves can also be produced using embossing techniques, such as heat embossing, to transfer fluidic patterns and components from a positive metal mold into thermoplastic materials. Halves can also be produced using soft lithography: PDMS is a suitable material which can be cast and set into positive molds of the desired fluidic system. Molds for this purpose can be produced using photoresists on silicon wafers as is conventionally done or using 3D printing or milling techniques to realize designs and patterns which have three-dimensional features. Halves can be joined together using epoxies or glues, ultrasonic welding, plasma or corona treatment, or any other suitable method depending upon the materials and application. Prior to being joined, reagents can be loaded into the appropriate chambers within either or both halves in dry or liquid format. If in liquid format, reagents can be further desiccated, vacuum dried, or lyophilized, amongst other processing techniques, in order to promote stability and consistency of the final assembled centrifugal microfluidic device. It shall also be noted that embodiments of the present invention are especially applicable to the field of centrifugal microfluidics, which entails processing of liquid volumes on the order of nanoliters to milliliters, and accordingly, the fluidics structures may have suitable dimensions for handling corresponding volumes of liquid. The following detailed description will serve to illustrate exemplary embodiments of the invention.

[0053] FIG. 1 is a layout view of an embodiment of the invention in the form of a cylindrical centrifugal fluidic device 21. The centrifugal fluidic device 21 has an indentation 20 along its periphery to facilitate mechanical engagement when the centrifugal fluidic device 21 is rotated. The centrifugal fluidic device 21 possesses a sample inlet 1 which is centered on the rotational center 19 of the centrifugal fluidic device 21. This sample inlet 1 is fluidly connected to central chambers 3 through a series of radially oriented channels 2 which connect to fluid inlets 49 of the central chambers 3. The central chambers 3 each possess a fluid outlet 50 and a gas outlet 51. In embodiments of the invention, such as the one depicted in FIG. 1, the fluid outlet 50 can be positioned closer to the fluid inlet 49 than the gas outlet 51 is positioned to the fluid inlet 49. This is so that when fluid is loaded into a central chamber 3 it first reaches the fluid outlet 50 and then displaces any gas remaining in the chamber 3 towards the gas outlet 51 and through a gas conduit 4 which allows displaced gas to exit the centrifugal fluidic device 21. The fluid outlet 50 is connected to a burst valve 5 which connects to a channel 6 which follows an azimuthal route around the rotational axis that progressively increases its radial distance from the rotational center. The channel 6 is lined on its radially distal side with respect to the rotational center 19 with metering chambers 7 and terminates in an excess fluid chamber 13. Each metering chamber 7 feeds into a channel 8 which functions as a burst valve and is positioned on the radially distal side of the metering chamber 7 with respect to the rotational center 19. This valve 8 feeds into a reaction chamber 9. Each reaction chamber 9 possesses a gas outlet 24 on its radially proximal side with respect to the rotational center 19 which connects to a gas conduit 14 which in turn connects to a gas outlet 15 through which gases may exit the centrifugal fluidic device 21.

[0054] FIG. 2 is a perspective view of an embodiment of the invention in the form of a cylindrical centrifugal fluidic device 21. This view of the centrifugal fluidic device 21 emphasizes structural aspects which cannot be appreciated in the layout view in FIG. 1. In an embodiment of the invention, the cross-sectional area of the channel 2 leading to the fluid inlet 49 of the central chamber 3 and the cross-sectional area of the fluid inlet 49 itself are larger than the cross-sectional area of the gas outlet 51 of the central chamber 3, which in turn is larger than the cross-sectional area of the fluid outlet 50. This ensures that fluid entering the central chambers 3 encounters greater resistance at the fluid outlet 50 and the gas outlet 51 than at the fluid inlet 49. This in turn ensures that once a central chamber 3 is filled with fluid, additional fluid which is supplied to the first fluid inlet 1 is motivated to move into another empty central chamber 3, as opposed to flowing through the fluid outlet 50 or gas outlet 51, thereby filling the central chambers 3 in succession until all are filled. The cross-sectional area of the first burst valve 5 is greater than the cross-sectional area of the burst valves 8 which lead into the reaction chambers 9. With the first burst valve 5 having a larger cross-sectional area, it permits fluid flow at a lower rotational frequency (ω.sub.low) while the reaction chamber burst valves 8 do not permit fluid flow at this same frequency. This ensures that liquid is metered by the metering chambers 7 at this frequency while excess fluid proceeds to the excess fluid chamber 13, instead of the fluid immediately flowing into the reaction chambers 9 and hampering proper partitioning.

[0055] FIG. 3 illustrates an exemplary embodiment of an apparatus used for centrifugal pumping of the centrifugal fluidic device 21. The fluidic device 21, which features an indentation 20 for mechanical engagement, is loaded onto a rotor 25. This rotor 25 features a protuberance 30 which mechanically engages with the indentation 20. The rotor 25 is joined to the drive shaft 27 of a motor 26. The rotor 25 can be fastened to the drive shaft 27 using an interference fit, set screw, adhesive, or any other suitable means. The motor 26 is controlled by a controller module 29 via an electrical connection 28. The controller module 29 can be pre-programmed to drive the motor 26 at a set of pre-determined speeds. These speeds are determined such that the drive shaft 27, rotor 25, and fluidic device 21 all rotate at a suitable frequency to properly motivate fluids within the fluidic device 21. These frequencies can be empirically determined and will vary depending on the dimensions of the centrifugal fluidic device 21, the materials and methods used to fabricate it, and the composition of the sample to be processed by the centrifugal fluidic device 21, among other variables and parameters. The controller module 29 can be a computer, microcontroller, or any other suitable apparatus capable of setting the speed of the motor 26.

[0056] FIG. 4A, FIG. 4B, and FIG. 4C illustrate filling of the central chambers 3 of the centrifugal fluidic device 21. FIG. 4A shows the filling of the first of three central chambers 3. Note that due to the chambers 3 being identical, their sequence of filling is random. A sample is loaded via the sample inlet 1 and progresses through a first channel 2 and through the central chamber's fluid inlet 49 into the central chamber 3 with pressure being applied to the sample inlet 1. This pressure can be supplied via syringe, pipette, or any other suitable means and can be manual or automated. Arrows indicate the general movement of the sample fluid as it enters the central chamber 3. It continues to do this, and in embodiments where the fluid outlet 50 is closer to the fluid inlet 49 than the gas outlet 51 is to the fluid inlet 49, the fluid will first reach the fluid outlet 50 and continue to displace any remaining gas in the central chamber 3 through the gas outlet 51 and into the gas conduit 4 which leads out of the centrifugal fluidic device 21. The fluid cannot proceed past the fluid outlet 50 because the portion of the central chamber 3 leading up to the gas outlet 51 presents a path of less resistance. Once the sample fluid reaches the gas outlet 51, a combination of surface tension and flow resistance present at the gas outlet 51 due to narrowing of the central chamber 3 prevents further fluid flow into the central chamber 3. At this point, the central chamber 3 is filled as depicted in FIG. 4B. With pressure and fluid still being applied to the sample inlet 1, the sample will now take the path of least resistance, which due to its larger cross-sectional area is the channel 2 leading to the fluid inlet 49 of either of the remaining empty central chambers 3. The filling process repeats with the remaining central chambers 3 as it did with the first central chamber 3, until all three central chambers 3 are filled as depicted in FIG. 4C. At the stage depicted in FIG. 4C, pressure is no longer applied to the sample inlet 1.

[0057] Once the sample fluid is partitioned into the central chambers 3, it can be distributed using centrifugation to downstream fluidics modules, regardless of their azimuthal position on the fluidic device 21 relative to the rotational center 19. The first stages of the centrifugal distribution are depicted in FIGS. 5A, 5B, and 5C. Initially, the central chambers 3 are filled as shown in FIG. 5A. The fluidic device 21 is then rotated, initiating from 0 Hertz until reaching a pre-determined rotational frequency (ω.sub.low). At or above this threshold frequency, the fluid in the central chamber 3 exerts enough pressure to flow through the first burst valve 5. The fluid is then motivated from the central chamber 3, through the fluid outlet 50 and the burst valve 5, and into the downstream channel 6, as depicted in FIG. 5B. Motivated by centrifugal force, the fluid continues to flow through the channel 6 and fills the metering chambers 7 as it progresses, as depicted in FIG. 5C.

[0058] FIGS. 6A, 6B, and 6C illustrate the final stages of fluid distribution to the reaction chambers 9. As shown in FIG. 6A, the metering chambers 7 are filled and the remaining sample fluid still flows through the channel 6 under centrifugal pressure. This stage is typically fleeting as the fluid generally flows rapidly through the channel 6. Excess fluid that cannot be accommodated by the metering chambers 7 continues to flow through the channel 6 until reaching the excess fluid chamber 13 where it collects. Meanwhile the metering chambers 7 remain filled, thereby precisely partitioning the fluid, as shown in FIG. 6B. At this point, the rotational frequency of the centrifugal fluidic device 21 is increased from ω.sub.low to another, higher rotational frequency which is also pre-determined, ω.sub.high. At this higher rotational frequency, the fluid in the metering chambers 7 exerts enough pressure to move past the second set of burst valves 8 and into the reaction chambers 9, as shown in FIG. 6C. As the fluid moves into the reaction chambers 9, it displaces gas previously present in the reaction chambers 9 through a gas outlet 24 and into a gas conduit 14. This gas conduit 14 provides a common route for gas exiting all the reaction chambers 9 through their gas outlets 24 to move towards an ultimate gas outlet 15 which permits displaced gases to exit the centrifugal fluidic device 21. At this stage, with the reaction chambers 9 filled with partitioned sample, a multiplexed assay can commence once the appropriate reaction conditions are satisfied.

[0059] FIG. 7 is a layout view of an alternative embodiment of the invention as a centrifugal fluidic device 32. This embodiment possesses features which are homologous to those in the other centrifugal fluidic device 21, and should serve to illustrate one of the many ways in which embodiments of the invention can be realized. As in the other centrifugal fluidic device 21, this fluidic device 32 features an indentation 31 for mechanical engagement and a fluid inlet 33 for sample input. This centrifugal fluidic device 32 features a larger number of central chambers 37 and associated fluid inlets 46, fluid outlets 47, and gas outlets 48. There are channels 34 which route fluid from the sample inlet 33 to the fluid inlets 46 of the central chambers 37. There are also gas conduits 35 which permit gas displaced through the gas outlets 48 of the central chambers 37 to leave the centrifugal fluidic device 32. There are burst valves 36 between the fluid outlets 47 and secondary fluid channels 38, with the secondary fluid channels 38 functioning to route fluid to a larger number of metering chambers 39, valves 40, and reaction chambers 41. This increased number of reaction chambers 41 relative to the other centrifugal fluidic device 21 can provide for enhanced multiplexing capabilities which can entail assays that are broader, more specific, or feature technical replicates. As in the other centrifugal fluidic device 21 the secondary channels 38 in this centrifugal fluidic device 32 terminate in excess fluid chambers 44, and each reaction chamber 41 possesses a gas outlet 42 which feeds into a shared gas conduit 45 which connects to a gas outlet 43. This centrifugal fluidic device 32 can be centrifugally pumped in a similar manner to the other centrifugal fluidic device 21. Specifically, it can be rotated at a first, lower rotational frequency (ω.sub.low) to motivate fluid from the central chambers 37 radially outwards towards downstream fluidic structures. Once the fluid has been metered by the metering chambers 39, the centrifugal fluidic device 32 can then be rotated at a second, higher rotational frequency (ω.sub.high) to motivate fluid from the metering chambers 39 past the valves 40 and into the reaction chambers 41. At this point, depending on the necessary reactions conditions (i.e. temperature), a multiplexed assay can begin.

[0060] Embodiments of the invention can serve a large number of industrial applications. With suitable manufacturing techniques, a variety of reagents can be pre-loaded into the reaction chambers of the centrifugal fluidic devices, permitting a broad spectrum of multiplexed assays to be performed. These assays can include but are not limited to assessments of metal, chemical, and biological contaminants in water supplies, quantification of protein concentrations, and analysis of nucleic acids. With respect to analysis of nucleic acids, there are a number of specific applications. These can include genotyping assays, which are useful for selective breeding of livestock and crops, forensic tests in criminal investigations, screenings for genetic diseases, and verifications of familial relations. Additionally, analyses of nucleic acids are useful in food testing, where it can be used to test food products for biological contaminants (i.e. Escherichia coli, Salmonella enterica). Nucleic acid analysis is also useful for diagnosis of diseases in crops and livestock. Furthermore, embodiments of the invention which support nucleic acid analysis would be useful for medical diagnostics, permitting diagnosis of various pathogenic entities and permitting rapid public health responses to disease outbreaks. Such assays for the analysis of nucleic acids can be realized, for example, by the pre-loading of lyophilized polymerase chain reaction reagents into the reaction chambers of the centrifugal fluidic devices. Different sets of primers, responsible for detecting different sequences of nucleic acids, can be pre-loaded into the separate reactions chambers, thereby permitting multiplexing capabilities in a single centrifugal microfluidic device. This technology would therefore be useful to academic research, industry, medicine, and society as a whole

[0061] While the present invention has been depicted as several embodiments and specified in reference to these embodiments, they should not be considered for purposes of limitation. There are numerous alterations, permutations, and equivalent embodiments which fall within the scope of this invention and would be evident to those of ordinary skill in the art. The following appended claims are intended to include all such alterations, permutations and equivalent embodiments which fall within the true spirit and scope of the present invention. In the claims that follow, reference signs are not to be construed as limiting the claims.