U.S. patent application number 12/617286 was filed with the patent office on 2010-04-15 for microfluidic analysis system.
This patent application is currently assigned to STOKES BIO LIMITED. Invention is credited to Tara Dalton, Mark Davies.
Application Number | 20100092987 12/617286 |
Document ID | / |
Family ID | 34278702 |
Filed Date | 2010-04-15 |
United States Patent
Application |
20100092987 |
Kind Code |
A1 |
Davies; Mark ; et
al. |
April 15, 2010 |
MICROFLUIDIC ANALYSIS SYSTEM
Abstract
A microfluidic analysis system (1) performs polymerase chain
reaction (PCR) analysis on a bio sample. In a centrifuge (6) the
sample is separated into DNA and RNA constituents. The vortex is
created by opposing flow of a silicon oil primary carrier fluid
effecting circulation by viscous drag. The bio sample exits the
centrifuge enveloped in the primary carrier fluid. This is pumped
by a flow controller (7) to a thermal stage (9). The thermal stage
(9) has a number of microfluidic devices (70) each having thermal
zones (71, 72, 73) in which the bio sample is heated or cooled by
heat conduction to/from a thermal carrier fluid and the primary
carrier fluid. Thus, the carrier fluids envelope the sample,
control its flowrate, and control its temperature without need for
moving parts at the micro scale.
Inventors: |
Davies; Mark; (Limerick,
IE) ; Dalton; Tara; (Limerick, IE) |
Correspondence
Address: |
BROWN RUDNICK LLP
ONE FINANCIAL CENTER
BOSTON
MA
02111
US
|
Assignee: |
STOKES BIO LIMITED
Limerick
IL
|
Family ID: |
34278702 |
Appl. No.: |
12/617286 |
Filed: |
November 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11366524 |
Mar 3, 2006 |
7622076 |
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12617286 |
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PCT/IE2004/000115 |
Sep 6, 2004 |
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11366524 |
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60500344 |
Sep 5, 2003 |
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60500345 |
Sep 5, 2003 |
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Current U.S.
Class: |
435/6.14 ;
435/287.2 |
Current CPC
Class: |
B01F 13/0059 20130101;
B01L 3/50273 20130101; B01L 3/502776 20130101; G01N 2035/00514
20130101; B01F 5/0057 20130101; B01L 7/525 20130101; G01N 35/1095
20130101; B01L 2200/0673 20130101; G01N 35/08 20130101; B01L
2400/0409 20130101; B01L 3/502784 20130101; B01L 2300/0816
20130101; C12Q 1/686 20130101; B01L 2300/0861 20130101; B01L
2200/0636 20130101; B01L 2400/0487 20130101; B01L 2200/141
20130101; B01L 2300/185 20130101; B01L 2300/087 20130101 |
Class at
Publication: |
435/6 ;
435/287.2 |
International
Class: |
C12Q 1/68 20060101
C12Q001/68; C12M 1/34 20060101 C12M001/34 |
Claims
1-20. (canceled)
21. A method for analyzing a sample, the method comprising: flowing
sample droplets enveloped in an immiscible carrier fluid to an
analysis stage; and analyzing the flowing droplets at the analysis
stage, wherein the sample droplets do not contact a surface of the
analysis stage.
22. The method according to claim 21, wherein the sample comprises
nucleic acid molecules
23. The method according to claim 22, wherein prior to analyzing,
the method further comprises amplifying the nucleic acid
molecules.
24. The method according to claim 23, wherein amplifying is by a
polymerase chain reaction.
25. The method according to claim 21, wherein analyzing comprises
optically detecting fluorescent tags on molecules in the
sample.
26. The method according to claim 21, wherein flowing is
continuously flowing.
27. The method according to claim 21, wherein the carrier fluid is
a biologically non-reactive fluid.
28. The method according to claim 27, wherein the biologically
non-reactive fluid is silicone oil.
29. A method of diagnosing cancer in a subject, the method
comprising: flowing sample droplets enveloped in an immiscible
carrier fluid to an analysis stage, wherein the sample droplets
comprise nucleic acid molecules, at least some of which are
suspected of having mutations that are indicative of a cancer;
amplifying the nucleic acid molecules in the droplets; hybridizing
labeled probes to the nucleic acid molecules in the droplets,
wherein the probes are specific for the mutations indicative of the
cancer; and detecting the labeled nucleic acids in the droplets at
the analysis stage, wherein the droplets do not contact a surface
of the analysis stage.
30. The method according to claim 29, wherein amplifying is by the
polymerase chain reaction.
31. The method according to claim 29 wherein the labeled probes are
fluorescently labeled probes.
32. The method according to claim 29, wherein flowing is
continuously flowing.
33. The method according to claim 29, wherein the carrier fluid is
a biologically non-reactive fluid.
34. The method according to claim 33, wherein the biologically
non-reactive fluid is silicone oil.
35. A biological sample analysis system, the system comprising: an
analysis stage comprising an inlet and an outlet, wherein the inlet
receives a flow of sample droplets enveloped in an immiscible
carrier fluid, wherein the droplets do not contact a surface of the
analysis stage and the droplets are analyzed as they flow to the
outlet of the stage.
36. The system according to claim 35, further comprising a thermal
cycling stage configured such that the enveloped droplets flow
through the thermal cycling stage prior to reaching the inlet of
the analysis stage.
37. The system according to claim 36, further comprising a sample
preparation stage fluidly coupled to the analysis stage.
38. The system according to claim 35, wherein the flow is a
continuous flow.
39. The method according to claim 35, wherein the carrier fluid is
a biologically non-reactive fluid.
40. The method according to claim 39, wherein the biologically
non-reactive fluid is silicone oil.
Description
[0001] This is a CONTINUATION of PCT/IE2004/000115 filed 6 Sep.
2004 and published in English, claiming the priorities of U.S.
Application No. 60/500,344 and 60/500,345, both filed on 5 Sep.
2003.
INTRODUCTION
[0002] 1. Field of the Invention
[0003] The invention relates to analysis systems for analysis such
as Polymerase Chain Reaction (PCR) analysis to detect the
population of rare mutated cells in a sample of bodily fluid and/or
tissue.
[0004] 2. Prior Art Discussion
[0005] It is known for at least the past decade that cancers have a
genetic cause. With the emergence of fast methods of sequencing and
the publication of the human genome, the motivation and methods are
available to find the genetic causes, both germline and somatic, of
the most prevalent cancers. Contemporary oncological research
suggests that there is a sequence of mutations that must occur for
a cancer to be life-threatening, called the multistage model.
Cancer could therefore be diagnosed earlier by detecting these
genetic markers thereby increasing the probability of cure.
However, even with refining of the sample, the target cells and
their DNA are still usually very rare, perhaps one part in
10.sup.6. The analysis system must therefore be able to perform
very effective amplification.
[0006] There are several methods of attempting to identify rare
cells in a sample of bio-fluid. A common method is to probe the
sample using known genetic markers, the markers being specific to
the type of mutation being sought, and then amplify the targets in
the sample. If the mutations or chromosomal aberations are present
then the amplification can be detected, usually using optical
techniques.
[0007] It is also possible, depending on the amplification used, to
use the Polymerase Chain Reaction (PCR) to detect the number of
mutated cells in the original sample: a number important as
firstly, it can be linked to the progress of the cancer and
secondly, it provides a quantitative measure with which to diagnose
remission. PCR is the enzyme-catalysed reaction used to amplify the
sample. It entails taking a small quantity of DNA or RNA and
producing many identical copies of it in vitro. A system to achieve
a PCR is to process the samples by thermally cycling them is
described in U.S. Pat. No. 5,270,183. However, this apparently
involves a risk of sample contamination by surfaces in the
temperature zones and other channels. Also, U.S. Pat. No. 6,306,590
describes a method of performing a PCR in a microfluidic device, in
which a channel heats, and then cools PCR reactants cyclically.
U.S. Pat. No. 6,670,153 also describes use of a microfluidic device
for PCR.
[0008] The invention is directed towards providing an improved
microfluidic analysis system for applications such as the
above.
SUMMARY OF THE INVENTION
[0009] According to the invention, there is provided a biological
sample analysis system comprising: [0010] a carrier fluid; [0011] a
sample supply; [0012] a sample preparation stage for providing a
flow of sample enveloped in a primary carrier fluid; [0013] at
least one analysis stage for performing analysis of the sample
while controlling flow of the sample while enveloped within the
primary carrier fluid without the sample contacting a solid
surface; and [0014] a controller for controlling the system.
[0015] In one embodiment, the analysis stages comprise a thermal
cycling stage and an optical detection stage for performance of a
polymerise chain reaction.
[0016] In another embodiment, the sample preparation stage
comprises a centrifuge for separation of samples from an input
fluid and for introduction of the samples to the primary carrier
fluid.
[0017] In a further embodiment, the centrifuge comprises a pair of
opposed primary carrier fluid channels on either side of a vortex
chamber, whereby flow of primary carrier fluid in said channels
causes centrifuging of sample in the vortex chamber and flow of
sample from the chamber into said channels.
[0018] In one embodiment, contact between the sample and the vortex
chamber surface is avoided by wrapping the sample in an initial
carrier fluid within the chamber.
[0019] In another embodiment, the controller directs separation in
the centrifuge either radially or axially due to gravity according
to nature of the input fluid such as blood containing the
sample.
[0020] In a further embodiment, the primary carrier fluid velocity
is in the range of 1 m/s to 20 m/s.
[0021] In one embodiment, the thermal cycling stage comprises a
microfluidic thermal device comprising a thermal zone comprising a
sample inlet for flow of sample through a sample channel while
enveloped in the primary carrier fluid, and a thermal carrier inlet
for flow of a thermal carrier fluid to heat or cool the sample by
heat conduction through the primary carrier fluid.
[0022] In another embodiment, the microfluidic thermal device
thermal zone further comprises separate sample and thermal outlets
positioned to allow flow of thermal carrier fluid into and out of
contact with the primary carrier fluid.
[0023] In a further embodiment, there is at least one pair of
opposed thermal carrier inlet/outlet pairs on opposed sides of a
sample channel.
[0024] In one embodiment, the thermal cycling stage comprises a
plurality of thermal zones.
[0025] In one embodiment, the microfluidic thermal device comprises
a plurality of thermal zones in series.
[0026] In another embodiment, the thermal cycling stage comprises a
plurality of microfluidic thermal devices in series.
[0027] In a further embodiment, the microfluidic thermal device
comprises a closed sample channel for re-circulation of sample with
successive heating or cooling in successive thermal zones.
[0028] In one embodiment, the controller directs flow of the
thermal and primary carrier fluids to control flowrate of sample by
enveloping within the primary carrier fluid and by viscous drag
between the thermal carrier fluid and the primary carrier
fluid.
[0029] In another embodiment, the primary carrier fluid is
biologically non-reactive.
[0030] In a further embodiment, the primary carrier fluid is a
silicone oil.
[0031] In one embodiment, the thermal carrier fluid is biologically
non-reactive.
[0032] In another embodiment, the thermal carrier fluid is a
silicone oil.
[0033] In a further embodiment, the temperatures and flowrates of
the carrier fluids are controlled to achieve a temperature ramping
gradient of 17.degree. C./sec to 25.degree. C./sec.
DETAILED DESCRIPTION OF THE INVENTION
Brief Description of the Drawings
[0034] The invention will be more clearly understood from the
following description of some embodiments thereof, given by way of
example only with reference to the accompanying drawings in
which:--
[0035] FIG. 1 is a diagram of an analysis system of the
invention.
[0036] FIG. 2 is a diagrammatic plan view of a centrifuge of the
system, and
[0037] FIG. 3 is a simulation diagram showing centrifuging;
[0038] FIG. 4 is a perspective view of the main body of a
microfluidic heater of the system;
[0039] FIG. 5 is a prediction velocity and temperature plot along a
thermal stage of the heater;
[0040] FIG. 6 is a centre line temperature profile in the flow
direction showing fast response of same in the heated zone; and
[0041] FIG. 7 is a plan view of an alternative microfluidic
heater.
DESCRIPTION OF THE EMBODIMENTS
[0042] Referring to FIG. 1 an analysis system 1 comprises a
controller 2 which interfaces with various stages. A carrier fluid
supply 4 delivers carrier fluid to a macro pump 5 which delivers it
at a high flowrate to a sample preparation stage 6. The latter also
receives a bio-fluid sample, and centrifuges the sample in a vortex
created by carrier fluid flow, as described in more detail below.
Reactants are supplied by a supply 8 to a flow controller 7 which
delivers streams of separated DNA with reactants enveloped in
carrier fluid to a thermal cycling stage 9. The DNA is amplified in
the stage 9 and optically detected by a detection stage 10.
Throughout the process the samples are enveloped in a biologically
non-reactive carrier fluid such as silicone oil. This avoids risk
of contamination from residual molecules on system channel
surfaces.
[0043] Referring to FIG. 2 a centrifuge device 20 of the sample
preparation stage 6 is illustrated diagrammatically. It comprises
opposed carrier supply lines 21 and 22 and a central vortex chamber
23 having a sample inlet out of the plane of the page. The
centrifuge 20 operates by primary carrier fluid in the channels 21
and 22 driving sample fluid in the chamber 23 into a vortex via
viscous forces at the interface between the two fluids. In this
embodiment, the carrier fluid is silicone oil mixed to be neutrally
buoyant with the sample.
[0044] The vortex, or centrifuge, is thus established without any
mechanical moving parts. The carrier fluid drives a vortex of the
sample to be centrifuged thereby avoiding the very many
difficulties of designing and operating moving parts at the micro
scale, particularly at high rotational speeds. FIG. 3 illustrates
the centrifuging activity, the greater density of dots indicating
higher flow velocities. The left-hand scale shows the velocity
range of 1 m/s to 20 m/s. The sample is wrapped in an initial
volume of carrier fluid within the chamber 23 to prevent surface
contamination.
[0045] This achieves a continuous throughput micro-centrifuging to
suitably extract DNA and RNA from cellular material. The bio-fluid
is centrifuged resulting in DNA and other bio-molecules of interest
accumulating at the bottom of the chamber, thereby providing an
efficient and simple method of manipulating micron and sub-micron
quantities of bio-fluid. The DNA and RNA are separated due to the
greater weight and viscous resistance of the DNA. Numerical
simulations (FIG. 3) of the flow show that tangential velocities of
up to 10 ms.sup.-1 are generated towards the edge of the vortex
core. Calculations reveal this to be equivalent to a rotational
speed of almost 20,000 rpm or 2,000 g in terms of a centrifugal
force. In order to achieve these levels of centrifugal force, the
carrier fluid is pumped at speeds of 5 ms.sup.-1 through the
system. In general, the desired carrier fluid speed is 1 m/s to 20
m/s. The device has further potential to be miniaturized to
centrifuge at up to 200,000 g, as these levels of force are
necessary for efficient separation of RNA and other smaller
cellular constituents and bio-molecules.
[0046] Overall, the continuous throughput centrifuge offers many
benefits over conventional technology. The device may also function
as a fluid mixing device by reversing the flow path of one of the
carrier fluid, if such is desired for an application. It is modular
in nature, meaning two or more systems can be placed together in
any configuration and run by the same control and power source
system. The centrifuge 20 has no moving parts thereby allowing
excellent reliability compared with a system having moving parts.
An important consequence of this feature is that manufacturing this
device at the micro-scale using current silicon processing or
micro-machining is readily achievable.
[0047] Referring to FIG. 4 a microfluidic thermal device 51 of the
stage 9 is shown. It comprises three successive thermal zones 52,
53, and 54. Each zone comprises a sample inlet 60 and an outlet 61
for flow of the bio sample in the primary carrier fluid. There are
also a pair of thermal carrier inlets 65 and 66, and a pair of
thermal carrier outlets 67 and 68 for each of the three zones. This
drawing shows only the main body, there also being top and bottom
sealing transparent plates.
[0048] The bio sample which enters the sample inlet 60 of each
stage is enveloped and conveyed by the carrier fluid henceforth
called the "primary carrier fluid". Thermal carrier fluid is
delivered at the inlets 65 and 66 to heat or cool the bio sample
via the primary carrier fluid.
[0049] As the sample remains in a low shear rate region of the
flow, mass transport by diffusion of sample species is kept to a
minimum. The low shear region reduces damage by shear to macro
molecules that may be carried by the bio sample. The arrangement of
a number (in this case three) of thermal zones in series offers
advantages to applications such as the polymerase chain reaction
(PCR) where rapid and numerous thermal cycles lead to dramatic
amplification of a DNA template strand.
[0050] The device 51 also acts as an ejector pump, in which the
velocity and hence the residency time of the sample is controlled
by controlling velocity of one or both of the carriers fluids. The
carrier flow parameters determine how long the sample remains at
the set temperature in each zone. This is often important, as
chemical reactions require particular times for completion. The
device 51 can therefore be tuned to the required residency times
and ramp rates by controlling the carrier velocity.
[0051] Referring to FIG. 5 a predicted velocity contour map at the
mid-height plane of a zone channel is shown. Carrier fluid enters
through the channels at the top and bottom left of the image and
exits through the channels at the top and bottom right of the
image. The sample fluid enters and exits through the central
channel. The different shadings of this map indicate the
velocities, the range being 0.01 m/s to 0.1 m/s.
[0052] In one example, sample fluid enters through the central
channel at the left of the image at a temperature of 50.degree. C.
and is heated to 70.degree. C. by the thermal carrier fluid.
[0053] FIG. 6 shows a temperature profile along a longitudinal
centreline of a thermal zone. A target temperature of 342 K is
achieved within an extremely short distance from entrance,
achieving an excellent temperature ramp rate of 20.degree. C./sec
over a distance of 0.05 m. In general, a ramping of 17.degree.
C./sec to 25.degree. C./sec is desirable for many applications.
[0054] The following table sets out parameters for one example. A
silicone oil, density matched to the density of the bio sample, is
used for both of the carrier fluids.
TABLE-US-00001 TABLE 1 Boundary Conditions and Fluid Properties
Overall Channel Dimensions 5 mm .times. 5 mm .times. 200 mm Wall
Boundary Condition outside of carrier Adiabatic flow interaction
zones Heat Transfer Carrier Fluid Inlet temperature 70.degree. C.,
90.degree. C., 110.degree. C. for each zone Sample/Transport
Carrier Inlet Pressure .sup. 0 Pa Heat Transfer Carrier Fluid Inlet
Pressure 0.2 Pa Sample/Transport Carrier Outlet Pressure 1.9 Pa
Heat Transfer Carrier Fluid Outlet Pressure 1.7 Pa Mass Diffusivity
1.3E-12 m.sup.2/s Approximate Temperature Gradient in Zones
20.degree. C./sec
[0055] Referring to FIG. 7, another microfluidic thermal device,
70, is shown. There are again three thermal zones, however in this
case on a generally rectangular closed circuit, with zones 71, 72,
and 73. The zones 71 and 73 are on one side and there is only a
single zone, 72, oh the other side. The thermal carrier fluid is
silicone oil, as is the primary carrier fluid. The thermal carrier
fluid for the zone 71 is at 68.degree. C., to ramp up the bio
sample to this temperature during residency in this zone. The zones
72 and 73 provide outlet temperatures of 95.degree. C. and
72.degree. C. respectively.
[0056] The optical detection stage 10 is positioned over the
microfluidic device 70 to analyse the sample. The silicone oil is
sufficiently transparent to detect the fluorescently tagged
molecules.
[0057] It will be appreciated that the invention achieves
comprehensive control over bio sample flowrate and temperature,
with no risk of contamination from device surfaces. The invention
also achieves integrated pumping and thermal cycling of the sample
without moving parts at the microscale. There are very high
throughputs as measured by processing time for one sample.
[0058] The system is expected to have a low cost and high
reliability due to the absence of micro scale moving parts. The
system also allows independent control and variation of all PCR
parameters for process optimisation.
[0059] The invention is not limited to the embodiments described
but may be varied in construction and detail.
* * * * *