Fluid mixing in low aspect ratio chambers
A method and system for performing mixing in a low volume, low aspect ratio microfluidic chamber (3) is described. Two or more mixing bladders (13,15) formed adjacent the microfluidic chamber are inflated and deflated in reciprocating fashion to cause inward and outward deflection of discrete regions of the chamber wall to mix fluid within the chamber. Mixing bladders are actuated by air or another gas, or by a liquid such as water, pumped in and out of the bladders with a pump which may be located remote from the microfluidic device including the microfluidic chamber. In an alternative embodiment, mixing is generated by applying alternating mechanical forces to a surface of a flexible chamber forming device. The microfluidic chamber may be a hybridization chamber formed on a microarray (25) slide with the use of a microarray interface device, or it may be a microfluidic chamber formed in various other types of microfluidic devices.
This application is a continuation-in-part of PCT Application PCT/US02/07113, filed Mar. 8,2002, which application claims the benefit of U.S. Provisional Application 60/274,389, filed Mar. 9, 2001, U.S. Provisional Application 60/284,427, filed Apr. 17, 2001, U.S. Provisional Application 60/313,703, filed Aug. 20, 2001, and U.S. Provisional Application 60/339,851, filed Dec. 12, 2001. It is also a continuation-in-part of PCT Application PCT/US02/______, filed Aug. 2, 2002 and identified by Attorney Docket No. 3153.2.17. The foregoing applications are incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to the area of microfluidic devices. In particular, it. relates to methods and systems for agitating or mixing fluids in chambers of microfluidic devices. More particularly, it relates to methods and systems for generating agitation or mixing in low aspect ratio chambers formed on substrates bearing immobilized biological or biochemical samples or compounds.
2. Description of Related Art
A variety of biological and chemical assays have been developed for detecting the presence of compounds of interest in samples. In the biomedical field, methods for detecting the presence of specific nucleotide sequences, proteins or peptides are utilized, for example, in diagnosing various medical conditions, determining predisposition of patients to diseases, and performing DNA fingerprinting. In general, biological and chemical assays are based on exposing an unknown sample to one or more known reactants and monitoring the progress or measuring the outcome of the reaction. There is currently a high level of interest in the development of high throughput methods for performing multiple biological and chemical analyses of this type simultaneously, quickly, and conveniently.
One recently developed method for performing multiple chemical reactions simultaneously is to form a microarray of multiple spots of reactant molecules on a planar substrate such as a glass microscope slide, typically in a two-dimensional grid pattern, and apply liquid reagents and reactants to the slide to contact multiple spots simultaneously. Various reaction steps may be performed with the bound molecules in the microarray, including exposure of bound reactant molecules to liquid reagents or reactants, washing, and incubation steps. It is typical to immobilize known reactants on the substrate, expose an unknown liquid sample to the immobilized reactants, and query the reaction products in order to characterize the sample. However, it is also possible to immobilize one or more unknown samples on the substrate and expose them to a liquid containing one or more known reactants.
Microarrays are frequently used in analysis of DNA samples, but may also be used in diagnostic testing of other types of samples. Spots in microarrays may be formed of various large biomolecules, such as DNA, RNA, and proteins, smaller molecules such as drugs, co-factors, signaling molecules, peptides or oligonucleotides. Cultured cells may also be grown onto microarrays. As an example, if it is desired to detect the presence of particular DNA sequences in a patient sample, the sample is exposed to a microarray of spots formed of oligonucleotides having sequences complementary to sequences of interest. The occurrence of hybridization between the sample and a known sequence in a particular spot then indicates the presence and perhaps, additionally the quantity, of the sequence associated with that spot in the sample.
Microarrays offer great potential for performing complex analyses of samples by carrying out multiple detection reactions simultaneously. However, some of the current limitations of microarrays are the time and care required to process slides, the difficulty in obtaining consistent, high quality results, and limited sensitivity, which makes detection of low-expression genes difficult. The need for high quality microarray processing is particularly pronounced because individual microarray slides are expensive and only limited quantities of the samples used in the reactions may be available, making it particularly important to obtain good results consistently.
It is often desirable that reactions performed on microarrays consume minimal quantities of sample, due to the limited sample availability, as noted above. However, when small quantities of sample fluid are spread out over the area of the microarray, the fluid layer is very thin, leading to the possibility that, if no mixing is provided, the sample fluid will become locally depleted of a particular sequence over the spot binding that sequence. As target is depleted, reaction kinetics slow, resulting in a lower signal. This is a greater problem for low-abundance sequences. It is considered particularly desirable that hybridization be performed in a low-volume chamber, with mixing. Low volumes allow for higher concentration of reactants that are in limited supply, while mixing maintains initial kinetic rate and thus produces more reaction products.
A number of approaches have been proposed for providing mixing on microarray slides. These include applying acoustic energy to the hybridization mixing (e.g., PCT publication No. WO/0170381 or U.S. Pat. No. 5,922,591), or pumping fluids in and out of the hybridization chamber or pumping fluids back and forth between several chambers or between separate compartments of a single chamber (e.g., PCT publication WO/0201184, U.S. Pat. No. 5,922,591), sometimes with the inclusion of dividers, particles, or bubbles within the chamber to enhance mixing. However, these methods depend on the use of relatively large sample volumes, large hybridization chambers, and inconvenient or complicated equipment, and in some cases require the use of specially designed slides or other substrates. There remains a need for a system that provides a mixing function in a low volume hybridization chamber suitable for use with common microarray slides.
SUMMARY OF THE INVENTIONThe present invention is a method and system for providing mixing in low-volume hybridization chambers suitable for use with common microarray slides. The mixing technology according to the invention may be incorporated into several types of microarray interface devices suitable for forming low-volume hybridization chambers, as described in commonly-owned patent applications PCT Application PCT/US02/07113, filed Mar. 8, 2002 and PCT Application PCT/US02/______, filed Aug. 2, 2002.
The novel mixing mechanism is not limited to use in hybridization chamber devices, and may also be incorporated into other types of fluid handling devices to generate fluid movement and mixing in many types of microfluidic chambers or channels, particularly those having low aspect ratio chambers or channels having at least one microscale dimension.
Mixing according to the invention is produced by the inflation and deflation of mixing bladders located adjacent to the microfluidic chamber or channel causing inward or outward deflection of the chamber wall, and consequently displacement of fluid within the chamber. Inward deflection of the chamber wall in one region of the chamber is accompanied by outward deflection of the chamber wall in another region of the chamber, so that the total volume of the chamber remains substantially constant. The mixing bladders may be formed from recesses or openings in the device structure covered by a thin, flexible membrane. The flexible membrane may be formed integrally with the material in which the recess is formed, or may be a sheet of flexible sheet material adhered thereto.
Bladders are activated by positive and negative air (or other gas) pressures that may be generated remote to the microfluidic device. Alternatively, water or other liquid may be pumped in and out of the bladders to generate deflections of the chamber wall. Bladders and associated air (fluid) lines can be incorporated into the design of microfluidic devices relatively simply and inexpensively, and therefore are suitable for use in devices intended for one-time use.
In a further alternative embodiment of the device, externally applied mechanical forces may be used to deflect the chamber wall and thus produce mixing in low aspect ratio chamber.
BRIEF DESCRIPTION OF THE FIGURES
The invention is illustrated in the schematic view of
The microarray interface device shown in
The device in
The device of
As shown in
Use of the devices depicted in
Pressure and Vacuum Sources.
Various types of pressure sources may be used to inflate and deflate mixing bladders in the inventive device. To simultaneously apply positive pressure to one bladder while applying negative pressure (vacuum) to the other bladder, a reciprocating pressure source 91, as illustrated in
Various types of pumps can be used to generate positive and negative pressures. In some cases, the action of the pump may not be readily reversed, so valves may be used to connect the mixing bladders alternately to the positive and negative pressure ends of the pump. The positive or negative connections of a pump may be connected to one or more manifolds which in turn are connected to multiple mixing bladders on one or multiple devices. The inventors have found that a 12 VDC air compressor is sufficient to drive mixing in four devices of the type illustrated in
In the presently preferred embodiment of the invention, mixing bladders are driven by positive and negative pressures of equal magnitude but opposite sign. However, in theory it is only necessary that some sort of pressure differential be applied to generate mixing, and the practice of the invention is not limited to the use of balanced positive and negative pressures. For example, it would be possible to utilize two positive pressures of different magnitudes, two negative pressures of different magnitudes, or positive and negative pressures of different magnitudes. In practice, of course, the ability of the device to withstand positive or negative pressures while maintaining its structural integrity may limit the pressures that may be used to generate mixing.
Although it is preferred to pump air into and out of the bladders to drive fluid mixing, it would also be possible to pump another gas or a liquid into and out of the bladders to provide pumping, and this possibility is considered to fall within the scope of the invention. Moreover, mixing has been described in connection with systems that use two bladders, with one or both being actively inflated or deflated, but smaller or larger numbers of bladders may be used to provide mixing as well, being inflated or deflated in various patterns, and are considered to fall within the scope of the present invention.
In the presently preferred embodiment of the invention, the slide and attached microarray interface device are used in connection with an instrument that provides both heating and pressurized air. The instrument includes a hot block or slide warmer that holds multiple slides, and maintains the slides, interface devices, and hybridization chamber contents at the desired temperature during processing of the slide. The instrument preferably includes a light-proof thermal insulating cover that protects the labeled target from photo bleaching during prolonged incubations and maintains proper hybridization temperature. The instrument also includes one or more air manifolds to allow a single reciprocating air pump, or other pressure and/or vacuum source, to supply alternating positive and negative pressures to multiple microarray interface device units, as depicted in schematic form in
A variety of different fittings may be used to connect a source of pressurized air (or other gas or liquid) to mixing bladders in a device that incorporates pneumatic mixing. For example, if air channels connecting to mixing bladders simply lead to openings in a smooth exterior surface of the microarray interface device, air line connectors that connect to an air line from a pressure source may be attached to air channel openings by clamping to form a face seal, as shown, or via double-sided adhesive disks. In other embodiments of the invention, air channel openings may be provided with push-to-connect fittings, such as the simple barbed fitting 84 shown in cross section in
In the presently preferred method for pneumatic mixing, pressure is alternately increased in a first bladder and simultaneously decreased in the second bladder, and then decreased in the first bladder and simultaneously increased in the second bladder. Because of the small volume of the hybridization chamber, only very small deflections of the bladders are necessary to cause displacement of the fluid in the hybridization chamber. If a first bladder is inflated while a second bladder is evacuated by the same amount, there is a net movement of the fluid in the hybridization chamber in the direction of the second bladder, to fill the volume made available by the evacuation of the second bladder. When the procedure is reversed, the fluid in the hybridization chamber is made to flow in the opposite direction, toward the first bladder. It is preferred that the bladders are formed at either end of the hybridization chamber, separated by a region at least equal in area to the diaphragm regions, to provide better mixing. Moreover, it is also preferred that the bladders do not overlie the “active” region of the slide, on which the microarray is spotted, since it is possible that the bladder could touch the surface of the slide when inflated, and it is thought that this could disrupt any spots in the microarray that were contacted.
In the embodiment of the invention depicted in
Pneumatically actuated microfluidic interface mixing devices within the scope of the present invention produce agitation and mixing of fluid within low aspect ratio microfluidic chambers, such as hybridization chambers, through the use of pneumatically actuated mixing elements. The most basic approach is to pressurize and depressurize two mixing bladders, alternately and in opposition, as described above. A number of other pneumatic mixing schemes may be used, as well.
One alternative approach, illustrated in
It is preferred that the mixing bladders are not positioned directly over spots in a microarray. However, in some cases the spotted array 117 may be positioned close to the edge of the slide 25, as depicted in
In the interface device of
Another approach to mixing is to alternately pressurize each mixing bladder in turn, while allowing the opposite bladder to be open to the atmosphere. The diaphragm of the mixing bladder that is open to the atmosphere will then be passively deflected by increased pressure in the fluid in the hybridization chamber when pressure is applied to the other bladder.
Finally, it is also possible to apply a vacuum or negative pressure intermittently to either one or both of the bladders, while the opposite bladder is vented to the atmosphere and thus free to passively expand, to produce mixing. This approach requires that the system be configured as shown in
It is presently preferred that reciprocating pumping action be used, so that reaction chamber pressure and volume remain substantially constant during pumping. It is thought that, in the case of the adhesive laminate interface device, not only the passive diaphragm but also the entire relatively flexible interface device will tend to deflect if one bladder is actively pressurized but the other is not simultaneously depressurized, which may absorb the mixing force and lead to less effective mixing. Moreover, if the passive deflection of the diaphragms is not sufficient to relieve the pressure in the reaction chamber, the increased pressure could lead to separation of the lid from the slide, and hence leaking of fluid from the reaction chamber. However, various other pumping actions, including but not limited to those described herein, may be used instead and are considered to fall within the scope of the invention.
Interestingly, the flexible nature of the adhesive laminate interface device depicted in
Although in the situation described above, the difference in chamber height between the central region and periphery of the reaction chamber is produced in response to the inflation and deflation of mixing bladders used to produce fluid movement, it may also be possible to provide separate mechanisms for driving fluid movement and modifying chamber height. If the reaction chamber aside from the mixing bladders is sufficiently rigid that it does not flex passively in response to fluid movement, various displacement mechanisms could be used to displace the central region of the interface device to increase or decrease the height of the reaction chamber in its central region. Such displacement mechanisms could include mechanical linkages attached to the wall of the interface device to cause displacement. Another displacement mechanism would be to form part or the entire wall of the chamber from a material that would change its dimensions in response to a change in a parameter such as electrical field, temperature, moisture, etc. By coordinating inward and outward displacement of the reaction chamber wall with pumping of fluid back and forth within the chamber (by pumping mechanisms such as pneumatic mixing bladders or other mechanisms as may be known to those of ordinary skill in the art), circulating fluid patterns may be generated within the reaction chamber.
The pneumatic mixing structures according to the present invention are not restricted to use in devices that form reaction or hybridization chambers on slides, and may also be incorporated into a variety of other microfluidic devices.
The structure shown in
Another variation of the present invention is to use pneumatic mixing bladders to generate mixing in multiple reaction chambers simultaneously.
In the embodiments of the invention depicted in
The present invention is a method and system for generating fluid mixing within a low aspect ratio chamber by deflecting two or more regions of the chamber wall inward and outward, to move fluid back and forth while maintaining a substantially constant chamber volume. In the preferred embodiment of the invention, flexible regions of the chamber wall (diaphragms) are moved inward and outward by increasing and or decreasing pressure in mixing bladders adjacent the diaphragm regions. However, it will be appreciated that deflection of flexible wall regions may be produced by the application of pressure to the chamber wall by other methods. For example, rather than inflating mixing bladders to deflect diaphragms, it would be possible to apply mechanical force to deflect diaphragms. Moreover, in a device such as the adhesive laminate microarray interface device 1 depicted in
The present invention is described and disclosed in connection with a number of examples. However, the scope of the invention is not limited to the specific examples provided herein, but is intended to include various modifications as may be devised by those of ordinary skill in the art, and is defined by the claims appended hereto.
Claims
1. A microfluidic device comprising:
- a. at least one low aspect ratio chamber comprising: i. two substantially parallel main walls; ii. a perimeter wall forming a boundary of said chamber and defining a length and width of said chamber, said chamber being further bounded by said two main walls, the distance between said main walls being small with respect to the length of said chamber; and iii. at least two flexible diaphragm regions located in said parallel main walls at opposite ends of said at least one chamber and adapted to flex inward and outward with respect to said chamber; and
- b. at least one inlet port through which fluid may be introduced into said at least one low aspect ratio chamber, wherein said at least one inlet port is sealable to maintain a substantially constant volume within said chamber.
2. The microfluidic device of claim 1, wherein said microfluidic device comprises a plurality of low aspect ratio chambers, wherein each of said low aspect ratio chambers comprises:
- a. two substantially parallel main walls;
- b. a perimeter wall forming a boundary of said chamber and defining a length and width of said chamber, said chamber being further bounded by said two main walls, the distance between said main walls being small with respect to the length of said chamber; and
- c. at least two flexible diaphragm regions located in said parallel main walls at opposite ends of said at least one chamber.
3. The microfluidic device of claim 2, wherein each of said at least two flexible diaphragm regions is located adjacent to a bladder connected to an external pressure source and adapted to flex inward or outward in response to pressure changes in said bladder, and wherein one said bladder is located adjacent to diaphragm regions of multiple chambers.
4. The microfluidic device of claim 1, wherein said flexible diaphragm regions are separated by a region at least equal in area to one of said diaphragm regions.
5. The microfluidic device of claim 1, wherein said flexible diaphragm regions displace between about 0.1% and about 50% of the volume of said chamber.
6. The microfluidic device of claim 1, wherein said flexible diaphragm regions displace between about 1% and about 30% of the volume of said chamber.
7. The microfluidic device of claim 1, wherein said microfluidic device further comprises a chemically active region on at least one of said parallel main walls, and wherein said flexible diaphragm regions are positioned so that they do not overlay said chemically active region.
8. The microfluidic device of claim 2, wherein the ratio of the distance between said main walls to the length of said chamber is between about 1:300 and about 1:10,000.
9. The microfluidic device of claim 2, wherein the ratio of the distance between said main walls to the length of said chamber is between about 1:100 and about 1:1,000.
10. The microfluidic device of claim 2, wherein the distance between said main walls is between about 10 μm and about 50 μm.
11. The microfluidic device of claim 2, wherein the distance between said main walls is between about 15 μm and about 30 μm.
12. The microfluidic device of claim 2, wherein the distance between said main walls is between about 50 μm and about 300 μm.
13. The microfluidic device of claim 1, wherein said at least two flexible diaphragm regions are located at opposite ends of one of said main walls.
14. The microfluidic device of claim 1, wherein one flexible diaphragm region is located on one wall, and at least one other flexible diaphragm region is located on the other main wall.
15. The microfluidic device of claim 1, wherein each of said at least two flexible diaphragm regions is located adjacent to a bladder connected to an external pressure source, and adapted to flex inward or outward in response to changes in pressure within said bladder.
16. The microfluidic device of claim 15, wherein said pressure source changes the pressure of a gas or gaseous mixture within said bladder.
17. The microfluidic device of claim 15, wherein said pressure source changes the pressure of a liquid within said bladder.
18. The microfluidic device of claim 1, wherein each of said at least two flexible diaphragm regions is adapted to flex inward or outward in response to mechanical pressure delivered by a mechanical actuator.
19. The microfluidic device of claim 18, wherein said mechanical actuator comprises a roller or a brayer.
20. The microfluidic device of claim 18, wherein said mechanical actuator comprises mechanical feet adapted to alternately apply and release pressure to said flexible diaphragm regions.
21. The microfluidic device of claim 1, wherein said device comprises a substantially rigid base material.
22. The microfluidic device of claim 21, wherein said diaphragm regions are formed integrally with said substantially rigid base material.
23. The microfluidic device of claim 21, wherein said diaphragm regions are formed by a method selected from molding, cutting, machining, printing methods, etching, vapor deposition, and embossing.
24. The microfluidic device of claim 21, wherein said diaphragm regions are formed from flexible sheet material adhered to said substantially rigid base material.
25. The microfluidic device of claim 1, wherein said device is formed from flexible material.
26. The microfluidic device of claim 25, wherein said diaphragm regions are formed by a method selected from molding, cutting, machining, printing methods, etching, vapor deposition, and embossing.
27. The microfluidic device of claim 25, wherein said diaphragm regions are formed from flexible sheet material adhered to said substantially rigid base material.
28. The microfluidic device of claim 1, further comprising at least one outlet port through which fluid may escape from said at least one low aspect ratio chamber, wherein said at least one outlet port is sealable to maintain a substantially constant volume within said chamber.
29. The microfluidic device of claim 1, further comprising a plurality of outlet ports through which fluid may escape from said at least one low aspect ratio chamber, wherein each said outlet port is salable to maintain a substantially constant volume within said chamber
30. The microfluidic device of claim 29, wherein said chamber comprises a plurality of outlet regions tapering toward said outlet ports.
31. A reaction chamber forming device comprising an open low aspect ratio chamber adapted to be sealed against a substrate, said chamber comprising:
- a. at least one substantially planar main wall, comprising two flexible diaphragm regions adapted to flex inward and outward with respect to said chamber in response to applied pressure;
- b. a perimeter wall forming a boundary of said chamber and defining a length and width of said chamber, the height of said perimeter wall defining the height of said chamber, said height of said chamber being small with respect to the length of said chamber, said height of said chamber being small with respect to the length of said chamber;
- c. at least one inlet port through which fluid may be introduced into said chamber;
- d. at least one outlet port through which fluid may be removed or released from said chamber; and
- e. a gasket adapted to reversibly seal said open low aspect ratio chamber to a planar surface of a substrate bearing a sample to form a closed low aspect ratio chamber containing said sample and having one wall formed by said surface of said substrate.
32. The microfluidic device of claim 31, wherein the height of said chamber is between about 10 μm and about 50 μm.
33. The microfluidic device of claim 31, wherein the height of said chamber is between about 15 μm and about 30 μm.
34. The microfluidic device of claim 31, wherein the height of said chamber is between about 50 μm and about 300 μm.
35. The reaction chamber forming device of claim 31, further comprising at least one bladder adjacent to said main wall, wherein said main wall is adapted to flex inward and outward with respect to said chamber in response to inflation and deflation of said bladder.
36. The reaction chamber forming device of claim 31, wherein said device comprises a substantially rigid base material.
37. The reaction chamber forming device of claim 36, wherein said diaphragm regions are formed integrally with said substantially rigid base material.
38. The reaction chamber forming device of claim 37, wherein said diaphragm regions are formed by a method selected from molding, cutting, machining, printing methods, etching, vapor deposition, and embossing.
39. The reaction chamber forming device of claim 37, wherein said diaphragm regions are formed from flexible sheet material adhered to said substantially rigid base material.
40. The reaction chamber forming device of claim 31, wherein said device comprises a base structure formed of flexible material.
41. The reaction chamber forming device of claim 40, wherein said diaphragm regions are formed by a method selected from molding, cutting, machining, printing methods, etching, vapor deposition, and embossing.
42. The reaction chamber forming device of claim 40, wherein said diaphragm regions are formed from flexible sheet material adhered to said base structure.
43. The reaction chamber forming device of claim 31, wherein said microfluidic device comprises a plurality of open low aspect ratio chambers, wherein each of said open low aspect ratio chambers comprises:
- a. a substantially planar main wall;
- b. a perimeter wall forming a boundary of said chamber and defining a length and width of said chamber, the height of said perimeter wall defining the height of said chamber, said height of said chamber being small with respect to the length of said chamber;
- wherein said gasket comprises a plurality of openings formed therethrough, each opening corresponding to one said chamber.
44. The microfluidic device of claim 43, further comprising at least one bladder adjacent to the main walls of multiple said chambers, wherein said main walls are adapted to flex inward and outward with respect to said chambers in response to inflation and deflation of said bladder, wherein said at least one bladder is connected to an external pressure source and adapted to flex inward or outward with respect to said plurality of chambers in response to pressure changes in said bladder.
45. The microfluidic device of claim 31, wherein the ratio of the distance between said main walls to the length of said chamber is between about 1:30 and about 1:10,000.
46. The microfluidic device of claim 31, wherein the ratio of the distance between said main walls to the length of said chamber is between about 1:100 and about 1:1,000.
47. The microfluidic device of claim 31, wherein the ratio of the distance between said main walls to the length of said chamber is between about 1:200 and about 1:300.
48. The microfluidic device of claim 31, wherein said at least one outlet port is sealable to maintain a substantially constant volume within said chamber.
49. The microfluidic device of claim 31, comprising a plurality of outlet ports through which fluid may escape from said at least one low aspect ratio chamber, wherein each said outlet port is sealable to maintain a substantially constant volume within said chamber.
50. The microfluidic device of claim 49, wherein said chamber comprises a plurality of outlet regions tapering toward said outlet ports.
51. A fluid handling device comprising:
- a. low aspect ratio chamber formed in a base structure;
- b. at least one inlet through which fluid can be introduced into said low aspect ratio chamber, wherein said at least one inlet is sealable to maintain a substantially constant volume within said chamber;
- c. a first mixing bladder located at a first end of said chamber;
- d. a first channel communicating with said first mixing bladder;
- e. a second mixing bladder located at a second end of said chamber; and
- f. a second channel communicating with said second mixing bladder;
- wherein said first and second mixing bladders may be alternately and reciprocally inflated and deflated to produce movement of fluid within said chamber while maintaining said chamber at said substantially constant volume.
52. The fluid handling device of claim 5 1, wherein said base structure is formed of flexible material.
53. The fluid handling device of claim 52, wherein said first and second mixing bladders are formed from a layer of a flexible sheet material secured over recesses formed in said base structure.
54. The fluid handling device of claim 52, wherein each of said first and second mixing bladders is formed from a separate diaphragm of a flexible sheet material secured over a recess formed in said base structure.
55. The fluid handling device of claim 52, wherein each of said first and second mixing bladders is formed from a balloon-like structure separately formed and secured within said chamber.
56. The fluid handling device of claim 51, wherein said base structure is formed of a rigid or semi-rigid material.
57. The fluid handling device of claim 56, wherein said first and second mixing bladders are formed from a layer of a flexible sheet material secured over recesses formed in said base structure.
58. The fluid handling device of claim 56, wherein each of said first and second mixing bladders is formed from a separate diaphragm of a flexible sheet material secured over a recess formed in said base structure.
59. The fluid handling device of claim 56, wherein each of said first and second mixing bladders is formed from a balloon-like structure separately formed and secured within said chamber.
60. The fluid handling device of claim 56, wherein said base structure is formed from at least two layers of rigid material secured together, and wherein each of said first and second mixing bladders comprises:
- a. a diaphragm formed integrally with a layer of said base structure; and
- b. a recess formed in a face of a layer of said base structure;
- wherein said recess is enclosed by securing together two layers of said base structures.
61. The fluid handling device of claim 60, wherein said diaphragm is formed by molding, cutting, machining, printing methods, etching, vapor deposition, and embossing.
62. The fluid handling device of claim 51, wherein said first and second mixing bladders are inflated and deflated by gas pressure differentials transmitted via said first and second channels.
63. The fluid handling device of claim 5 1, wherein said first and second mixing bladders are inflated and deflated by liquid pressure differentials transmitted via said first and second channels.
64. A method of mixing fluid within a low aspect ratio chamber, said chamber comprising:
- a. two substantially planar and substantially parallel main walls;
- b. a perimeter wall forming a boundary of the low aspect ratio chamber and defining a length and width of said chamber, said chamber being further bounded by said two main walls, the distance between said main walls being small with respect to the length of said chamber; and
- c. at least first and second flexible diaphragm regions located in at least one of said parallel main walls at opposite ends of said chamber;
- d. at least first and second mixing bladders, one mixing bladder adjacent to each said flexible diaphragm region; and
- e. an inlet port through which fluid may be introduced into said low aspect ratio chamber;
- said method comprising the steps of: i. loading a volume of fluid into said chamber via said inlet port; ii. sealing said inlet port to retain said volume of fluid within said chamber; iii. inflating said first mixing bladder to cause deflection of said first flexible diaphragm region into said chamber; and iv. deflating said first mixing bladder to cause deflection of said first flexible diaphragm region out of said chamber;
- wherein said volume of said chamber remains substantially constant during said steps of inflating and deflating said first mixing bladder.
65. The method of claim 64, wherein steps iii) and iv) are repeated one or more times, and wherein each repetition of steps iii) and iv) comprises one mixing cycle.
66. The method of claim 65, wherein each said mixing cycle has a cycle time of between about 5 seconds and about 3 hours.
67. The method of claim 65, wherein each said mixing cycle has a cycle time of between about 5 seconds and about 1 minute.
68. The method of claim 64, wherein said first mixing bladder is actively inflated and actively deflated.
69. The method of claim 64, wherein said first mixing bladder is actively inflated and passively deflated.
70. The method of claim 64, wherein said first mixing bladder is passively inflated and actively deflated.
71. The method of claim 64, comprising the further step of alternately deflating said second mixing bladder to cause deflection of said second flexible diaphragm region out of said chamber as said first mixing bladder is inflated, and inflating said second mixing bladder to cause deflection of a second flexible diaphragm region into said chamber as said first mixing bladder is deflated.
72. The method of claim 71, wherein said first and second mixing bladders are actively inflated and actively deflated.
73. The method of claim 71, wherein said first and second mixing bladders are actively inflated and passively deflated.
74. The method of claim 71, wherein said first and second mixing bladders are passively inflated and actively deflated.
75. The method of claim 71, wherein said first and second mixing bladders are connected to inlet and outlet ends of a common pressure source.
76. The method of claim 71, wherein said first and second mixing bladders are connected to separate pressure sources calibrated to produce equal and opposite pressures.
77. The method of claim 71, wherein each of said first and second mixing bladders is switched alternately between a positive pressure source and a negative pressure source through the use of a valve.
78. The method of claim 64, wherein said second mixing bladder is vented to the atmosphere, so that said second flexible diaphragm is permitted to passively deflect outward when said first flexible diaphragm is deflected inward, and passively deflect inward when said first flexible diaphragm is deflected outward.
79. The method of claim 64, wherein said first and second mixing bladders are alternately and reciprocally switched between a positive pressure source and atmospheric pressure.
80. The method of claim 64, wherein said first and second mixing bladders are alternately and reciprocally switched between a negative pressure source and atmospheric pressure.
81. The method of claim 64, wherein said first and second mixing bladders are alternately and reciprocally switched between a positive pressure source and a negative pressure source.
82. A fluid handling device comprising a low aspect ratio chamber, the low aspect ratio chamber comprising
- a. a substantially planar first main wall;
- b. a substantially planar second main wall positioned substantially parallel with respect to said first main wall; and
- c. a perimeter wall bounding the region between said first and second main walls, the height of said perimeter wall defining a microscale distance between said first and second main walls that is significantly smaller than the length and width of said first and second main walls;
- wherein edges of said first and second main walls are fixed with respect to said perimeter wall, wherein at least one said first and second main walls comprises a central wall region adapted to flex inward and outward with respect to said chamber, wherein inward flexing of said central wall region causes the distance between said first and second main walls to be less in the central wall region of said chamber than in a peripheral region adjacent said perimeter wall, and wherein outward flexing of said central wall region causes the distance between said first and second main walls to be greater in said central wall region than in said peripheral region.
83. The device of claim 82, further comprising at least one pumping mechanism for pumping fluid back and forth alternately in a first direction and a second direction within said low aspect ratio chamber, wherein said at least one central wall region is flexed outward when fluid is driven in said first direction, causing fluid to move preferentially in the central region of said chamber, and wherein said at least one central wall region is flexed inward when fluid is driven in said second direction, causing fluid to move preferentially along the sides of said chamber, thereby producing circulating movement of said fluid within said chamber.
84. The device of claim 83, wherein said at least one central wall region is flexed inward and outward actively by a displacement mechanism.
85. The device of claim 83, wherein said at least one central wall region is flexed inward and outward passively by the force of the fluid as it is moved back and forth in said chamber by said pumping mechanism
86. A method of mixing fluid within a microfluidic device comprising a substantially fixed volume low aspect ratio chamber, wherein at least selected regions of the wall of said device adjacent said chamber can be moved inward or outward with respect to said chamber, the method comprising the steps of:
- a. filling said chamber with fluid;
- b. sealing said chamber to retain fluid within said chamber;
- c. pumping said fluid in a first direction within said chamber;
- d. deflecting a central wall region off the wall of said device so that in at least a portion of said chamber, the height of said chamber is greater in the central wall region of said chamber than on the periphery of said chamber;
- e. pumping said fluid in a second direction within said chamber;
- f. deflecting a central wall region off the wall of said device so that in at least a portion of said chamber, the height of said chamber is less in the central wall region of said chamber than on the periphery of said chamber;
- g. repeating steps c. through f. to generate circulating fluid movement within said chamber.
87. A method of mixing fluid within a fluid-filled microfluidic device comprising a substantially fixed volume low aspect ratio chamber, wherein at least selected regions of the wall of said device adjacent said chamber can be moved inward or outward with respect to said chamber, the method comprising applying pressure alternately to movable wall regions on opposite ends of said chamber by a brayer, a roller, or mechanical feet.
88. A microfluidic device comprising:
- a. at least one low aspect ratio chamber comprising: i. two substantially parallel main walls; ii. a perimeter wall forming a boundary of said chamber and defining a length and width of said chamber, said chamber being further bounded by said two main walls, the distance between said main walls being small with respect to the length of said chamber; iii. at least one flexible diaphragm region located in one of said parallel main walls adapted to flex inward and outward with respect to said chamber; and iv. and least one vent, said vent being sufficiently long that fluid displaced by the inward and outward flexing of said at least one flexible diaphragm region can move up and down within said vent while remaining contained within said vent; and
- b. at least one inlet port through which fluid may be introduced into said at least one low aspect ratio chamber.
89. The device of claim 82, further comprising at least one displacement mechanism operably connected to the central wall region and at least one fluid injector operably connected to the low aspect ratio chamber, wherein when the central wall region is flexed outward, fluid moves preferentially in the central region of the chamber, and when the central wall region is flexed inward, fluid moves preferentially along the sides of the chamber, thereby allowing control over fluid movement within the chamber.
90. The device of claim 89, wherein the displacement mechanism is capable of flexing at least one central wall region inward and outward.
91. The device of claim 89, wherein the fluid injector is capable of driving fluid flow through the low aspect chamber.
92. The device of claim 89, wherein the displacement mechanism is selected from the group consisting of one or more mechanical feet, one or more brayers and one or more injectors.
93. The device of claim 89, wherein the fluid injector is selected from the group consisting of micropipette, pipette, microsyringe and syringe.
94. The device of claim 82, further comprising at least one displacement mechanism operably connected to the central wall region capable of flexing at least one central wall inward and outward and at least one fluid injector operably connected to the low aspect ratio chamber capable of driving fluid flow through the low aspect ration chamber, wherein when the central wall region is flexed outward, fluid moves preferentially in the central region of the chamber, and when the central wall region is flexed inward, fluid moves preferentially along the sides of the chamber, thereby allowing control over fluid movement within the chamber.
95. The device of claim 82, further comprising at least one displacement mechanism operably connected to the central wall region and at least one pump operably connected to the low aspect ratio chamber, wherein when the central wall region is flexed outward, fluid moves preferentially in the central region of the chamber, and when the central wall region is flexed inward, fluid moves preferentially along the sides of the chamber, thereby allowing control over fluid movement within the chamber.
96. The device of claim 95, wherein the displacement mechanism is capable of flexing at least one central wall region inward and outward.
97. The device of claim 95, wherein the pump is capable of driving fluid flow through the low aspect chamber.
98. The device of claim 95, wherein the displacement mechanism is selected from the group consisting of one or more mechanical feet, one or more brayers and one or more pumps.
99. The device of claim 95, wherein the pump is selected from the group consisting of micropipette, pipette, microsyringe and syringe.
100. The device of claim 95, further comprising at least one displacement mechanism operably connected to the central wall region capable of flexing at least one central wall inward and outward and at least one pump operably connected to the low aspect ratio chamber capable of actuating fluid flow through the low aspect ration chamber, wherein when the central wall region is flexed outward, fluid moves preferentially in the central region of the chamber, and when the central wall region is flexed inward, fluid moves preferentially along the sides of the chamber, thereby allowing control over fluid movement within the chamber.
Type: Application
Filed: Aug 13, 2002
Publication Date: Jan 27, 2005
Inventors: Nils Adey (Salt Lake City, UT), Ming Lei (Midvale, UT), Mark Spute (Salt Lake City, UT), John Jensen (Salt Lake City, UT), Darin Beutel (Salt Lake City, UT), Devan Slade (West Jordan, UT), Michael McNeely (Sandy, UT)
Application Number: 10/487,126