U.S. patent application number 14/110678 was filed with the patent office on 2014-04-24 for system and method for charging fluids.
This patent application is currently assigned to STOKES BIO LIMITED. The applicant listed for this patent is Brian Chawke, Kieran Curran, David McGuire, Michael Sayers, Noel Sirr. Invention is credited to Brian Chawke, Kieran Curran, David McGuire, Michael Sayers, Noel Sirr.
Application Number | 20140111901 14/110678 |
Document ID | / |
Family ID | 46026914 |
Filed Date | 2014-04-24 |
United States Patent
Application |
20140111901 |
Kind Code |
A1 |
Chawke; Brian ; et
al. |
April 24, 2014 |
System and Method for Charging Fluids
Abstract
Devices, systems, and methods for charging fluids are disclosed.
The charging of fluids improves the mixing of fluids in
microfluidic systems. The charging is performed by producing an ion
field (50) between an ionizing electrode (20) and an opposed ground
electrode (30). A fluid-containing vessel (40) is positioned
between the opposed electrodes and the ion field charges the fluid
(41) in the vessel.
Inventors: |
Chawke; Brian; (Limerick,
IE) ; Curran; Kieran; (Limerick, IE) ;
McGuire; David; (Limerick, IE) ; Sayers; Michael;
(Kerry, IE) ; Sirr; Noel; (Limerick, IE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chawke; Brian
Curran; Kieran
McGuire; David
Sayers; Michael
Sirr; Noel |
Limerick
Limerick
Limerick
Kerry
Limerick |
|
IE
IE
IE
IE
IE |
|
|
Assignee: |
STOKES BIO LIMITED
Limerick
IE
|
Family ID: |
46026914 |
Appl. No.: |
14/110678 |
Filed: |
April 6, 2012 |
PCT Filed: |
April 6, 2012 |
PCT NO: |
PCT/US12/32590 |
371 Date: |
December 18, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61473317 |
Apr 8, 2011 |
|
|
|
Current U.S.
Class: |
361/226 |
Current CPC
Class: |
B01F 13/0076 20130101;
B01L 3/502715 20130101; B01L 3/56 20130101; G01N 2001/4038
20130101; B01L 2200/0673 20130101; C12Q 1/686 20130101; B01F
13/0071 20130101; B01L 3/502784 20130101; B05B 5/035 20130101; B01L
2400/0415 20130101; B01L 2400/0406 20130101; G01N 1/38 20130101;
B01L 3/52 20130101; B01J 19/087 20130101; B01L 2300/0867 20130101;
B01L 3/50273 20130101 |
Class at
Publication: |
361/226 |
International
Class: |
B01L 3/00 20060101
B01L003/00 |
Claims
1. A fluid charging system comprising: an ionizing electrode
positioned adjacent to a fluid vessel; and a ground electrode
positioned adjacent to the fluid vessel, the fluid vessel
positioned between the ionizing electrode and the ground electrode;
wherein the ionizing electrode and the ground electrode are
configured to produce an ion field that charges fluid contained in
the fluid vessel.
2. The fluid charging system of claim 1, further comprising an
electrical power source connected to the ionizing electrode.
3. The fluid charging system of claim 2, wherein the electrical
power source comprises a static generator.
4. The fluid charging system of claim 1, further comprising a
resistor unit connected to the ionizing electrode.
5. The fluid charging system of claim 1, further comprising: an
electrical power source connected to the ionizing electrode; and a
resistor unit connected in series between the electrical power
source and the ionizing electrode.
6. The fluid charging system of claim 1, further comprising: a
static generator connected to the ionizing electrode; and a
resistor unit connected in series between the static generator and
the ionizing electrode.
7. The fluid charging system of claim 1, wherein the ionizing
electrode comprises: an emitter plate; and a plurality of emitter
pins connected to the emitter plate.
8. The fluid charging system of claim of claim 1, wherein the
ionizing electrode comprises: a stainless steel emitter plate; and
a plurality of emitter pins connected to the emitter plate, the
emitter pins comprising tungsten.
9. The fluid charging system of claim of claim 1, wherein the
ionizing electrode comprises: a stainless steel emitter plate; and
a plurality of tungsten carbide or tungsten alloy emitter pins
connected to the emitter plate.
10. The fluid charging system of claim of claim 1, wherein the
ground electrode comprises an aluminum or aluminum alloy ground
plate.
11. The fluid charging system of claim of claim 1, wherein the
ionizing electrode comprises: an emitter plate having a cross-shape
comprising a first member and an intersecting second member; and at
least five emitter pins connected to the emitter plate at opposed
ends of the first member, at opposed ends of the second member, and
at an intersection of the first member and the second member.
12. The fluid charging system of claim of claim 1, further
comprising a fluid sampling device configured to withdraw fluid
from the fluid vessel.
13. The fluid charging system of claim of claim 1, further
comprising a fluid sampling device configured to withdraw fluid
from the fluid vessel, the fluid sampling device comprising a
plurality of tubes in fluid communication with the fluid
vessel.
14. The fluid charging system of claim of claim 13, wherein the
ionizing electrode comprises: an emitter plate having a cross-shape
comprising a first member and an intersecting second member; and a
plurality of emitter pins connected to the emitter plate; wherein
at least one tube is positioned through an open quadrant region of
the emitter plate.
15. The fluid charging system of claim of claim 1, further
comprising a fluid sampling device configured to withdraw fluid
from the fluid vessel, the fluid sampling device comprising a
plurality of sheaths, wherein each sheath surrounds a plurality of
tubes.
16. The fluid charging system of claim of claim 15, wherein the
ionizing electrode comprises: an emitter plate having a cross-shape
comprising a first member and an intersecting second member; and a
plurality of emitter pins connected to the emitter plate; wherein
at least one sheath is positioned through an open quadrant region
of the emitter plate.
17. The fluid charging system of claim of claim 12, further
comprising a liquid bridge in fluid communication with the fluid
sampling device.
18. The fluid charging system of claim of claim 17, wherein the
liquid bridge is configured to segment a charged fluid withdrawn
from the fluid vessel, the liquid bridge comprising: a first inlet
port in fluid communication with the fluid sampling device; a
second inlet port in fluid communication with a source of
immiscible fluid; an outlet port; and a chamber, wherein the inlet
ports and the outlet port open into the chamber and are structured
and positioned so that a periodic fluid instability in a fluid
droplet formed between the first inlet port and the outlet port
segments the fluid withdrawn from the fluid vessel into fluid
droplets separated by the immiscible fluid that are withdrawn from
the chamber through the outlet port.
19. The fluid charging system of claim of claim 17, wherein the
liquid bridge is configured to mix fluid withdrawn from the fluid
vessel with one or more additional fluids that are miscible with
the fluid withdrawn from the fluid vessel, the liquid bridge
comprising: a first inlet port in fluid communication with the
fluid sampling device; at least one additional inlet port in fluid
communication with a source of one or more additional fluids; an
outlet port; and a chamber, wherein the inlet ports and the outlet
port open into the chamber and are structured and positioned so
that first fluid droplets formed at the first inlet port contact
and mix with one or more additional fluid droplets formed at the at
least one additional inlet port, thereby forming unstable funicular
bridges that rupture, thereby forming mixed fluid droplets
separated by immiscible carrier fluid that are withdrawn from the
chamber through the outlet port.
20. The fluid charging system of claim of claim 17, wherein the
liquid bridge is configured to mix fluid withdrawn from the fluid
vessel with one or more additional fluids that are miscible with
the fluid withdrawn from the fluid vessel, the liquid bridge
comprising: a chamber; an inlet port opening into the chamber, the
inlet port in fluid communication with the fluid sampling device
and one or more sources of the one or more additional fluids, the
inlet port serially providing fluid droplets of the fluid withdrawn
from the fluid vessel and the one or more additional fluids
separated by an immiscible carrier fluid; an first outlet port
opening into the chamber, the first outlet port configured to
withdraw a portion of the immiscible carrier fluid entering the
chamber; and a second outlet port; wherein the inlet port and the
outlet ports are structured and positioned so that trailing fluid
droplets transporting through the inlet port contact and mix with
leading droplets formed at the inlet port, thereby forming mixed
fluid droplets that are withdrawn from the chamber through the
second outlet port as mixed fluid droplets separated by immiscible
carrier fluid.
21. (canceled)
22. The fluid charging system of claim of claim 17, wherein the
liquid bridge is in fluid communication with a thermal cycler for
performing amplification reactions.
23. The fluid charging system of claim of claim 22, wherein the
fluid vessel contains a master mixture that is charged to improve
mixing of the master mixture with reaction-specific reactants.
24-45. (canceled)
Description
TECHNICAL FIELD
[0001] This disclosure is directed to systems and methods for
charging fluids to improve the admixture of fluids, such as, for
example, in microfluidic systems.
BACKGROUND
[0002] Microfluidics involves micro-scale systems and devices that
handle small volumes of fluids. Because microfluidics can
accurately and reproducibly control and dispense small fluid
volumes, in particular volumes less than 1 .mu.L, application of
microfluidics has the capability to provide significant
cost-savings in technical fields such as, for example, chemical,
biochemical, and biological sample processing. The use of
microfluidics technology can reduce cycle times, shorten
time-to-results, and increase throughput in various applications.
Furthermore, incorporation of microfluidics technology can enhance
system integration and automation in various applications.
[0003] Given the relatively small dimensions of microfluidic
devices or components thereof, microfluidic systems involve
construction and design that differs from macro-scale fluidic
systems. Simple scaling down in size of macro-scale devices to a
microfluidic scale is often not a successful design option. For
example, liquid flow in microfluidic devices physically differs
from that of macro-scale size devices. Because liquid flow tends to
be laminar, surface flux and surface tension start to dominate and,
as a result, physical effects not seen at the macro-scale become
significant at the microfluidic scale. Other differences at the
microfluidic scale include, for example, faster thermal diffusion,
predominately laminar flow, significant capillary forces, and
significant electrostatic forces.
SUMMARY
[0004] Embodiments disclosed herein are directed to a fluid
charging system configured to charge a fluid contained in a fluid
vessel. The fluid charging system comprises an ionizing electrode
and a ground electrode. The ionizing electrode and the ground
electrode are positioned adjacent to the fluid vessel. The ionizing
electrode and the ground electrode are opposed so that the fluid
vessel is positioned between the ionizing electrode and the ground
electrode. The ionizing electrode and the ground electrode are
configured to produce an ion field that contacts fluid contained in
the fluid vessel, thereby charging the fluid.
[0005] Other embodiments disclosed herein are directed to a method
for charging a fluid contained in a vessel. The method comprises
producing an ion field between an ionizing electrode and a ground
electrode. A fluid-containing vessel is positioned adjacent to and
between the ionizing electrode and the ground electrode so that the
fluid vessel is positioned between the ionizing electrode and the
ground electrode. The ion field produced by the ionizing electrode
and the ground electrode contacts fluid contained in the fluid
vessel, thereby charging the fluid.
[0006] It is understood that the invention disclosed and described
in this specification is not limited to the embodiments disclosed
in this Summary.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Various features and characteristics of the non-limiting and
non-exhaustive embodiments disclosed and described in this
specification may be better understood by reference to the
accompanying figures, in which:
[0008] FIG. 1 is a side view schematic diagram illustrating a fluid
charging system comprising an ionizing electrode and a ground
electrode that produce an ion field;
[0009] FIG. 2 is a side view schematic diagram illustrating a fluid
charging system comprising an ionizing electrode, a ground
electrode, a fluid vessel, and fluid sampling devices in fluid
communication with the fluid vessel;
[0010] FIG. 3a is a bottom view of a cross-shaped ionizing
electrode comprising a cross-shaped emitter plate and five emitter
pins; FIGS. 3b and 3c are side views of the ionizing electrode
shown in FIG. 3a; FIG. 3d is a perspective bottom view of the
ionizing electrode shown in FIGS. 3a, 3b, and 3c;
[0011] FIG. 4 is a perspective bottom view of an ionizing electrode
comprising a cross-shaped emitter plate and nine emitter pins;
[0012] FIG. 5a is a bottom view of an annular- and cross-shaped
ionizing electrode comprising an annular- and cross-shaped emitter
plate and nine emitter pins; FIGS. 5b and 5c are side views of the
ionizing electrode shown in FIG. 5a; FIG. 5d is a perspective
bottom view of the ionizing electrode shown in FIGS. 5a, 5b, and
5c;
[0013] FIG. 6a is a bottom view of an assembly comprising the
cross-shaped ionizing electrode shown in FIGS. 3a through 3d
connected to a resistor unit; FIG. 6b is a side view of the
assembly shown in FIG. 6a; FIG. 6c is a perspective bottom view of
the assembly shown in FIGS. 6a and 6b;
[0014] FIG. 7a is a bottom view of an assembly comprising the
annular- and cross-shaped ionizing electrode shown in FIGS. 4a
through 5d connected to a resistor unit; FIG. 7b is a side view of
the assembly shown in FIG. 7a; FIG. 7c is a perspective bottom view
of the assembly shown in FIGS. 7a and 7b;
[0015] FIG. 8 is a side view schematic diagram of a fluid charging
system comprising the assembly shown in FIGS. 6a through 6c, a
ground electrode, and a fluid vessel positioned between an adjacent
ionizing electrode and an adjacent ground electrode;
[0016] FIG. 9 is a top view schematic diagram of the assembly shown
in FIGS. 6a through 6c positioned so that the ionizing electrode is
adjacent to an open top end of a fluid vessel;
[0017] FIG. 10 is a side view schematic diagram of a fluid charging
system comprising the assembly shown in FIGS. 7a through 7c, a
ground electrode, and a fluid vessel positioned between an adjacent
ionizing electrode and an adjacent ground electrode;
[0018] FIG. 11 is a top view schematic diagram of the assembly
shown in FIGS. 7a through 7c positioned so that the ionizing
electrode is adjacent to an open top end of a fluid vessel;
[0019] FIG. 12 is a side view schematic diagram of a fluid charging
system comprising a static generator electrical power source;
[0020] FIG. 13 is a side view schematic diagram of a fluid charging
system comprising the cross-shaped ionizing electrode shown in
FIGS. 3a through 3d and fluid sampling devices positioned through
open quadrant regions of the emitter plate;
[0021] FIG. 14 is a top view schematic diagram of the assembly
shown in FIGS. 6a through 6c positioned so that the ionizing
electrode is positioned adjacent to an open top end of a fluid
vessel and showing fluid sampling devices positioned through open
quadrant regions of the emitter plate;
[0022] FIG. 15 is a top view schematic diagram of the assembly
shown in FIGS. 7a through 7c positioned so that the ionizing
electrode is positioned adjacent to an open top end of a fluid
vessel and showing fluid sampling devices positioned through open
quadrant regions of the emitter plate;
[0023] FIG. 16 is a side view schematic diagram of a fluid charging
system comprising the cross-shaped ionizing electrode shown in
FIGS. 3a through 3d and fluid sampling devices positioned through
open quadrant regions of the emitter plate;
[0024] FIG. 17 is a top view schematic diagram of the assembly
shown in FIGS. 6a through 6c positioned so that the ionizing
electrode is positioned adjacent to an open top end of a fluid
vessel and showing fluid sampling devices positioned through open
quadrant regions of the emitter plate;
[0025] FIG. 18 is a side view schematic diagram of a fluid charging
system comprising a static generator and a controller;
[0026] FIG. 19 is a side view schematic diagram of a fluid charging
system comprising a closed fluid vessel, an ionizing electrode
positioned inside and adjacent to the fluid vessel, and a ground
electrode positioned outside and adjacent to the fluid vessel;
[0027] FIG. 20 is a bottom view parametric model drawing of an
ionizing electrode assembly;
[0028] FIG. 21a is a bottom view of a ground electrode; FIG. 21b is
a side view of the ground electrode shown in FIG. 21a; FIG. 21c is
a perspective top view parametric model drawing of the ground
electrode shown in FIGS. 21a and 21b;
[0029] FIG. 22 is a circuit diagram for an interface between a
static generator and a remote PC used to control a fluid charging
system;
[0030] FIG. 23 is a circuit board layout diagram for an interface
between a static generator and a remote PC used to control a fluid
charging system; and
[0031] FIG. 24 is a perspective bottom view parametric model
drawing of the electrode assembly shown in FIG. 20, the ground
electrode shown in FIGS. 21a through 21c, a fluid vessel, and fluid
sampling devices.
[0032] The reader will appreciate the foregoing details, as well as
others, upon considering the following detailed description of
various non-limiting and non-exhaustive embodiments according to
the present disclosure.
DETAILED DESCRIPTION
[0033] Various embodiments are described and illustrated in this
specification to provide an overall understanding of the structure,
function, operation, manufacture, and use of the disclosed devices,
systems, and methods. It is understood that the various embodiments
described and illustrated herein are non-limiting and
non-exhaustive. Thus, the invention is not limited by the
description of the various non-limiting and non-exhaustive
embodiments disclosed in this specification. Rather, the invention
is defined solely by the claims. The features and characteristics
illustrated and/or described in connection with various embodiments
may be combined with the features and characteristics of other
embodiments. Such modifications and variations are intended to be
included within the scope of this specification. As such, the
claims may be amended to recite any features or characteristics
expressly or inherently described in, or otherwise expressly or
inherently supported by, this specification. Further, Applicants
reserve the right to amend the claims to affirmatively disclaim
features or characteristics that may be present in the prior art.
Therefore, any such amendments would comply with the requirements
of 35 U.S.C. .sctn.112, first paragraph, and 35 U.S.C.
.sctn.132(a). The various embodiments disclosed and described
herein can comprise, consist of, or consist essentially of the
features and characteristics as variously described herein.
[0034] Any patent, publication, or other disclosure material that
is said to be incorporated by reference herein, is incorporated
herein in its entirety unless otherwise indicated, but only to the
extent that the incorporated material does not conflict with
existing definitions, statements, or other disclosure material
expressly set forth in this disclosure. As such, and to the extent
necessary, the express disclosure as set forth herein supersedes
any conflicting material incorporated by reference herein. Any
material, or portion thereof, that is said to be incorporated by
reference herein, but which conflicts with existing definitions,
statements, or other disclosure material set forth herein is only
incorporated to the extent that no conflict arises between that
incorporated material and the existing disclosure material.
Applicant reserves the right to amend the present disclosure to
expressly recite any subject matter, or portion thereof,
incorporated by reference herein.
[0035] Reference throughout this specification to "various
embodiments," or the like, means that a particular feature or
characteristic described in connection with the embodiment is
included in at least one embodiment. Thus, use of the phrase "in
various embodiments," or the like, in this specification does not
necessarily refer to a common embodiment, and may refer to
different embodiments. Further, the particular features or
characteristics may be combined in any suitable manner in one or
more embodiments. Thus, the particular features or characteristics
illustrated or described in connection with various embodiments may
be combined, in whole or in part, with the features or
characteristics of one or more other embodiments without
limitation. Such modifications and variations are intended to be
included within the scope of the present disclosure. In this
manner, the various embodiments described in this specification are
non-limiting and non-exhaustive.
[0036] In various embodiments, a fluid charging system configured
to charge a fluid contained in a fluid vessel comprises an ionizing
electrode and a ground electrode. The ionizing electrode and the
ground electrode may be positioned adjacent to the fluid vessel.
The ionizing electrode and the ground electrode may be opposed so
that the fluid vessel is positioned between the ionizing electrode
and the ground electrode. The ionizing electrode and the ground
electrode are configured to produce an ion field that contacts
fluid contained in the fluid vessel, thereby charging the
fluid.
[0037] In various embodiments, a method for charging a fluid
contained in a vessel comprises producing an ion field between an
ionizing electrode and a ground electrode. A fluid-containing
vessel may be positioned adjacent to and between the ionizing
electrode and the ground electrode. The ion field produced by the
ionizing electrode and the ground electrode contacts the fluid
contained in the fluid vessel, thereby charging the fluid. The
devices, systems, and methods disclosed herein may be used to
produce a net charge in various fluids.
[0038] Fluid charged in the devices, systems, and methods disclosed
herein may be mixed with other fluids after being charged. The net
charge carried by the fluids charged in the devices, systems, and
methods disclosed herein may increase the extent of the mixing of
fluids in downstream devices, systems, and methods. For instance,
fluids carrying a net charge may exhibit improved mixing with other
miscible fluids when mixed with fluid plugs or droplets in an
immiscible carrier fluid in microfluidic system. In this manner,
the net charge may decrease undesirable static electric effects
observed in microfluidic systems that can adversely affect fluid
mixing.
[0039] FIG. 1 illustrates a fluid charging system 10 according to
various embodiments. The fluid charging system 10 comprises an
ionizing electrode 20 positioned adjacent to a fluid vessel 40 and
a ground electrode 30 positioned adjacent to the fluid vessel 40.
The ionizing electrode 20 is connected to an electrical power
source 60 via an electrical line 70. The ground electrode 30 is
grounded relative to the ionizing electrode 20 as indicated at 80.
The ionizing electrode 20 and the ground electrode 30 produce an
ion field 50 that contacts a fluid 41 contained in the fluid vessel
40, thereby charging the fluid 41. The ionizing electrode 20 and
the ground electrode 30 are opposed so that the fluid vessel 41 is
positioned between the ionizing electrode 20 and the ground
electrode 40. The ionizing electrode 20 is positioned adjacent to
an open top end of the fluid vessel 40, which facilitates contact
between the ion field 50 and the fluid 41.
[0040] In various embodiments, a fluid charging system comprises
one or more fluid sampling devices configured to withdraw charged
fluid from the fluid vessel, such as described and illustrated
below. In various embodiments, the fluid sampling devices may
comprise one or more tubes, such as, for example, capillary tubes,
configured to withdraw charged fluid from the fluid vessel. In
various embodiments, the fluid sampling devices may comprise one or
more sheaths, wherein each sheath surrounds one or more tubes, such
as, for example, capillary tubes, configured to withdraw charged
fluid from the fluid vessel. In various embodiments, the one or
more fluid sampling devices may be in continuous or discontinuous
fluid communication with the fluid vessel.
[0041] In various embodiments, fluid sampling devices may be
configured to withdraw segmented plugs or droplets of charged fluid
from a fluid vessel. The withdrawal and acquisition of charged
fluid may be performed in either a continuous operation or batch
operation mode. For example, fluid sampling devices may comprise,
for example, the devices described in United States Patent
Application Publication Nos. 2010/0304443 and 2010/0294048, which
are incorporated by reference herein. The devices described in
United States Patent Application Publication Nos. 2010/0304443 and
2010/0294048 may be configured to withdraw segmented fluid samples
from a vessel, wherein the segmented fluid samples are surrounded
by an immiscible carrier fluid.
[0042] Fluid charging systems including fluid sampling devices may
further include at least one robotics system to control the fluid
sampling devices. The robotics systems may control movement of the
sampling devices to control sample acquisition from the fluid
vessel. In various embodiments, the driving force for the
withdrawal of charged fluid by a fluid sampling device may be
provided by one or more pumps. An exemplary pump is shown in
International Patent Application Publication No. WO 2007/091229,
which is incorporated by reference herein. In various embodiments,
the fluid sampling devices may be configured to withdraw fluid
using the hydrostatic siphoning effect described in United States
Patent Application Publication No. 2010/0120635, which is
incorporated by reference herein.
[0043] FIG. 2 illustrates a fluid charging system 10 comprising
fluid sampling devices 45 in fluid communication with a fluid
vessel 40. The fluid sampling devices 45 are configured to withdraw
a fluid 41 from the fluid vessel 40, wherein the withdrawn fluid 41
has been charged by the ion field 50. Although FIG. 2 illustrates a
fluid charging system 10 comprising two (2) fluid sampling devices
45, it is understood that in various embodiments of the fluid
charging systems disclosed herein, one (1) fluid sampling device
may be employed or any plurality of fluid sampling devices may be
employed.
[0044] In various embodiments, the ionizing electrode comprises an
emitter plate and one or more emitter pins connected to the emitter
plate. The emitter plate may be made of a conductive metallic
material, such as, for example, a stainless steel alloy. The
emitter pins may be made of a metallic or ceramic material
comprising tungsten. For instance, the emitter pins may comprise
tungsten carbide, such as, for example, emitter pins made of
tungsten carbide or a cemented tungsten carbide (cermet) composite
material. Alternatively, the emitter pins may be made of a metal
alloy comprising tungsten, for example.
[0045] The emitter pins may be connected to a common side of the
emitter plate by soldering, for example. The emitter pins may be
connected to a common side of the emitter plate by other joining
techniques, such as, for example brazing, welding, and threaded
connection. For instance, the emitter pins may comprise a male
threaded stub and the emitter plate may comprise corresponding
female threaded bores or through-holes. Threaded mechanical
connection of the emitter pins to the emitter plate may allow for
the emitter pins of the ionizing electrode to be replaced without
having to also replace the emitter plate.
[0046] FIGS. 3a through 3d illustrate a cross-shaped ionizing
electrode 120 according to various embodiments. The cross-shaped
ionizing electrode 120 may comprise a cross-shaped emitter plate
121 and five (5) emitter pins 125 connected to the emitter plate
121. The cross-shaped emitter plate 121 may comprise a first member
122 and a second member 124. The first member 122 and the second
member 124 may intersect at a substantially 90-degree angle. The
five (5) emitter pins 125 may be connected to a common side of the
emitter plate 121, respectively positioned at the opposed ends of
the first member 122, at the opposed ends of the second member 124,
and at the intersection 127 of the first member 122 and the second
member 124. FIG. 4 illustrates an ionizing electrode 120'
comprising a cross-shaped emitter plate 121 and seven (7) emitter
pins 125.
[0047] The ionizing electrodes 120/120' illustrated in FIGS. 3a
through 4 may comprise through-holes 128 positioned at opposed ends
of the second member 124. The through-holes 128 may be configured
to mount the ionizing electrode 120 in relation to other components
of a fluid charging system, such as, for example, a fluid vessel, a
ground electrode, fluid sampling devices, support structures, and
the like. The emitter plate 121 illustrated in FIGS. 3a through 4
may have a monolithic construction, the emitter plate 121 being
formed from a single piece of material, such as, for example, a
stainless steel. However, it is understood that in various
embodiments, an emitter plate may comprise multiple discrete
segments, such as, for example, first and second members, that may
be metallurgically or mechanically joined together using techniques
such as, for example, soldering, brazing, welding, and mechanical
fastening.
[0048] FIGS. 5a through 5d illustrate an annular- and cross-shaped
ionizing electrode 220 according to various embodiments. The
annular- and cross-shaped ionizing electrode 220 comprises an
annular- and cross-shaped emitter plate 221 and nine (9) emitter
pins 225 connected to the emitter plate 221. The annular- and
cross-shaped emitter plate 221 may comprise an annular member 226,
a first linear member 222, and a second linear member 224. The
first linear member 222 and the second linear member 224 may
intersect at a substantially 90-degree angle to form a cross-shaped
portion, and the cross-shaped portion intersects the annular member
226 at opposed ends of the first and second linear members 222 and
224. The nine (9) emitter pins 225 may be connected to a common
side of the emitter plate 221, wherein eight (8) of the emitter
pins may be positioned equidistant from each other around the
annular member 226, and one (1) emitter pin may be positioned at
the intersection 227 of the first member 222 and the second member
224.
[0049] The emitter plate 221 illustrated in FIGS. 5a through 5d may
have a monolithic construction, the emitter plate 221 being formed
from a single piece of material, such as, for example, a stainless
steel. However, it is understood that in various embodiments, an
emitter plate may comprise multiple discrete segments, such as, for
example, an annular member and first and second linear members,
that are metallurgically or mechanically joined together using
techniques such as, for example, soldering, brazing, welding, and
mechanical fastening.
[0050] In operation, electrical current delivered to the ionizing
electrode concentrates at the tips of the emitter pins and ionizes
atoms and/or molecules comprising the surrounding air or other
gaseous atmosphere, producing an ion cloud. The ion cloud emits
from the emitter pins and moves toward the ground electrode along a
static electric field established between the ionizing electrode
and the ground electrode in accordance with the physical principles
of static electricity. This produces an ion field between the
ionizing electrode and the ground electrode. The polarity of the
ion field is the same as the polarity of the electrical current
provided to the ionizing electrode. Although the ion fields
illustrated in the figures presented herein are shown with a
positive polarity (+) symbol, it is understood that, in various
embodiments, the ion field may be of negative polarity. Materials
contacting the ion field become charged at the same polarity as the
ion field.
[0051] In various embodiments, a fluid vessel may be positioned
between and adjacent to the electrodes so that the ion field
contacts fluid contained within the fluid vessel, thereby charging
the fluid. The emitter pins may be connected to the side of the
emitter plate that faces an open top end of a fluid vessel, which
facilitates contact between the field produced by the ionizing
electrode and fluid contained in the fluid vessel to charge the
fluid. Although the ionizing electrodes illustrated in certain
figures presented herein are shown positioned adjacent an open top
end of a fluid vessel, it is understood that, in various
embodiments, the ionizing electrodes may be positioned adjacent to
any region or end of an open or closed fluid vessel, provided the
ionizing electrodes and ground electrodes are mutually positioned
in a spaced apart relationship.
[0052] In various embodiments, the shape and dimensions of an
emitter plate may be dependant upon the fluid charging system in
which the ionizing electrode is to be employed. In various
embodiments, the number, dimensions, and spatial orientation of
emitter pins connected to an emitter plate may be dependant upon
the fluid charging system in which the ionizing electrode is to be
employed. For instance, larger fluid vessels containing larger
volumes of fluid to be charged may require emitter plates having a
larger vessel-facing surface area and/or a greater number of
emitter pins to produce an ion field sufficient to charge the
volume of fluid in the vessel. In addition, the shape and
dimensions of an emitter plate may be controlled, at least in part,
by the dimensions and spatial orientation of other components of a
fluid charging system, such as, for example, the fluid vessel and
fluid sampling devices. In various embodiments, a fluid charging
system may comprise two or more discrete ionizing electrodes.
Embodiments comprising a plurality of ionizing electrodes may be
used with larger fluid vessels or multiple fluid vessels, for
example.
[0053] In various embodiments, a ground electrode may be made of a
conductive metallic material, such as, for example, aluminum or
aluminum alloys. The shape and dimensions of a ground electrode may
be dependant upon the fluid charging system in which the ground
electrode is to be employed. In various embodiments, a ground
electrode comprises a ground plate configured to seat and support a
fluid vessel. For instance, a circular-shaped ground plate may have
a diameter that substantially matches the diameter of a cylindrical
fluid vessel.
[0054] In various embodiments, a fluid vessel may be made of a
non-conductive material, such as, for example, plastic or glass.
The fluid vessel may be made of non-conductive material in order to
prevent a current from arcing from the ionizing electrode to the
vessel, which could cause undesirable sparking. In addition, the
presence of a conductive material between an ionizing electrode and
a ground electrode may cause distortion of the static electric
field between the electrodes, and distortion of the resulting ion
field, which could prevent the charging of fluid in the vessel.
Therefore, all additional system components adjacent to and between
an ionizing electrode and a ground electrode (e.g., fluid sampling
devices, support structures, and the like) may be made of
non-conductive materials.
[0055] In various embodiments, an ionizing electrode may be
connected to a high voltage electrical power source by a high
voltage cable that delivers current from the high voltage
electrical power source to the ionizing electrode. In various
embodiments, a high voltage cable may connect a high voltage
electrical power source to a resistor unit, and the resistor unit
may be connected to an ionizing electrode via a high voltage
electrical lead. In this manner, a resistor unit may be connected
in series between a high voltage electrical power source and an
ionizing electrode. A resistor unit decreases the amount of current
delivered to the ionizing electrode by the high voltage power
source, which may reduce the potential for sparking and provide for
stable ionic emission.
[0056] FIGS. 6a through 6c illustrate an assembly comprising a
resistor unit 75 connected to an ionizing electrode 120 via a high
voltage electrical lead 73 according to various embodiments. The
resistor unit 75 may also be connected to a high voltage cable 71
that may connect the assembly to a high voltage electrical power
source. In this manner, the resistor unit 75 may be connected in
series between the high voltage electrical power source and the
ionizing electrode 120. FIGS. 7a through 7c illustrate an assembly
comprising a resistor unit 75 connected to an ionizing electrode
220 via a high voltage electrical lead 73 according to various
embodiments. The resistor unit 75 may also be connected to a high
voltage cable 71 that may connect the assembly to a high voltage
electrical power source. In this manner, the resistor unit 75 may
be connected in series between the high voltage electrical power
source and the ionizing electrode 220.
[0057] FIG. 8 illustrates a fluid charging system 110 according to
various embodiments. The fluid charging system 110 comprises an
ionizing electrode 120 positioned adjacent to a fluid vessel 140
and a ground electrode 130 positioned adjacent to the fluid vessel
140. The ionizing electrode 120 may be connected to an electrical
power source 160 via a high voltage cable 171, a resistor unit 175,
and a high voltage electrical lead 173. The ground electrode 130
may be electrically grounded relative to the ionizing electrode
120. The ionizing electrode 120 and the ground electrode 130 may
produce an ion field 150 that contacts a fluid 141 contained in the
fluid vessel 140, thereby charging the fluid 141. The ionizing
electrode 120 and the ground electrode 130 may be opposed so that
the fluid vessel is positioned between the ionizing electrode 120
and the ground electrode 140. The ionizing electrode 120 may be
positioned adjacent to an open top end of the fluid vessel 140 with
the emitter pins 125 facing the vessel, which facilitates contact
between the ion field 150 and the fluid 141.
[0058] FIG. 8 schematically illustrates the vertical positioning of
the ionizing electrode 120 relative to the fluid vessel 140. FIG. 9
schematically illustrates the horizontal positioning of the
ionizing electrode 120 relative to the fluid vessel 140.
[0059] FIG. 10 illustrates a fluid charging system 210 according to
various embodiments. The fluid charging system 210 may comprise an
ionizing electrode 220 positioned adjacent to a fluid vessel 240
and a ground electrode 230 positioned adjacent to the fluid vessel
240. The ionizing electrode 220 may be connected to an electrical
power source 260 via a high voltage cable 271, a resistor unit 275,
and a high voltage electrical lead 273. The ground electrode 230
may be electrically grounded relative to the ionizing electrode
220. The ionizing electrode 220 and the ground electrode 230
produce an ion field 250 that contacts a fluid 241 contained in the
fluid vessel 240, thereby charging the fluid 241. The ionizing
electrode 220 and the ground electrode 230 may be opposed so that
the fluid vessel is positioned between the ionizing electrode 220
and the ground electrode 240. The ionizing electrode 220 may be
positioned adjacent to an open top end of the fluid vessel 240 with
the emitter pins 225 facing the vessel, which facilitates contact
between the ion field 250 and the fluid 241.
[0060] FIG. 10 schematically illustrates the vertical positioning
of the ionizing electrode 220 relative to the fluid vessel 240.
FIG. 11 schematically illustrates the horizontal positioning of the
ionizing electrode 220 relative to the fluid vessel 240.
[0061] In various embodiments, the electrical power source may
comprise a static generator. Static generators provide stable and
controllable current or voltage that may be used to produce an ion
field using an ionizing electrode in accordance with the physical
principles of static electricity. Examples of static generators
that may find utility in various embodiments disclosed herein
include the Fraser Model 7300 or Fraser Model 7330 static
generators available from Fraser Anti-Static Techniques Ltd.
(http://www.fraser-antistatic.co.uk/index.html). FIG. 12
illustrates a fluid charging system 110' similar to the fluid
charging system 110 illustrated in FIG. 8. The fluid charging
system 110' may comprise a static generator 165 that provides a
current to ionizing electrode 120 to produce ion field 150. The
ground electrode 130 may be connected to a ground lug on the static
generator 165 via an electrical line 181.
[0062] FIG. 13 illustrates a fluid charging system 110 comprising
fluid sampling devices 145. The fluid sampling devices 145 may be
configured to withdraw a fluid 141 from the fluid vessel 140,
wherein the withdrawn fluid 141 has been charged by the ion field
150. The fluid sampling devices 145 may comprise tubes in fluid
communication with the fluid vessel 140. As illustrated in FIG. 14,
the fluid sampling devices 145 may be positioned through open
quadrant regions 129 of the emitter plate portion of the
cross-shaped ionizing electrode 120. FIG. 15 shows analogous fluid
sampling devices 245 positioned through open quadrant regions 229
of an emitter plate portion of an annular- and cross-shaped
ionizing electrode 220.
[0063] FIG. 16 illustrates a fluid charging system comprising fluid
sampling devices 147. The fluid sampling devices 147 may be
configured to withdraw a fluid 141 from the fluid vessel 140,
wherein the withdrawn fluid 141 has been charged by the ion field
150. The fluid sampling devices 147 may comprise sheaths 148
surrounding a plurality of tubes 149 in fluid communication with
the fluid vessel 140. As illustrated in FIG. 17, the fluid sampling
devices 147 may be positioned through open quadrant regions 129 of
the emitter plate portion of the cross-shaped ionizing electrode
120. The fluid sampling devices 147 may comprise fluid sampling
devices such as, for example, the devices described in United
States Patent Application Publication Nos. 2010/0304443 and
2010/0294048, which are incorporated by reference herein.
[0064] In various embodiments, a fluid charging system may comprise
a controller to control the current and/or voltage output of an
electrical power source, such as, for example, a static generator.
The controller may comprise hardware, software, or a combination of
hardware and software configured to control the current and/or
voltage output of an electrical power source so that a stable ion
field charges fluid contained in a fluid vessel positioned between
a ground electrode and an ionizing electrode connected to the
current and/or voltage output of the electrical power source. FIG.
18 illustrates a fluid charging system comprising a controller 167
interfacing with a static generator 165. The voltage and/or current
output of the static generator 165 may be measured at 166 and sent
as an output signal to the controller 167. Based on the measured
current and/or voltage, the controller 167 may send an input signal
to the static generator 165 to adjust the current and/or voltage
output to the ionizing electrode.
[0065] Although not shown in FIG. 18, other system parameters may
be measured and used by the controller 167 to control the current
and/or voltage output of the static generator or other electrical
power source. For instance, current and/or voltage may be measured
at other locations within the system and used by the controller
167. Further, fluid dynamic parameters, such as, for example, the
fluid volume in a vessel, fluid flow rates, and/or fluid pressures,
may be measured and used to control the current and/or voltage
output of the static generator or other electrical power source in
order to provide an effective ion field to charge fluid in
accordance with the embodiments disclosed herein.
[0066] In various embodiments, the fluid charging systems disclosed
herein may comprise a closed fluid vessel. FIG. 19 illustrates a
fluid charging system 310 according to various embodiments. The
fluid charging system 310 may comprise an ionizing electrode 320
positioned inside and adjacent to a closed fluid vessel 340. A
ground electrode 330 may be positioned outside and adjacent to the
fluid vessel 340. The ionizing electrode 320 may be connected to an
electrical power source 360 via an electrical line 370. The ground
electrode 330 may be grounded relative to the ionizing electrode
320 as indicated at 380. The ionizing electrode 320 and the ground
electrode 330 produce an ion field 350 that contacts fluid 341
contained in the fluid vessel 340, thereby charging the fluid 341.
The ionizing electrode 320 and the ground electrode 330 may be
opposed so that the fluid vessel is positioned between the ionizing
electrode 320 and the ground electrode 340. The fluid charging
system 310 may also comprise fluid sampling devices (not
shown).
[0067] Although the fluid vessels described herein have been
illustrated without fluid communication ports, it is understood
that in various embodiments the fluid charging systems disclosed
herein may comprise open or closed fluid vessels comprising inlet
and/or outlet ports in addition to, or instead of, the fluid
sampling devices. For example, a fluid vessel may comprise one or
more inlet ports for adding fluid to the fluid vessel to replace
charged fluid that has been withdrawn by a fluid sampling device.
In various embodiments, the flow rate of fluid added to the fluid
vessel may be equal to the flow rate of fluid withdrawn from the
fluid vessel. In this manner, the fluid vessel may function as a
charging reservoir that contains a steady-state level of fluid. A
fluid vessel may also comprise one or more outlet or drain ports
for removing fluid from the fluid vessel.
[0068] In various embodiments, a fluid sampling device may be in
fluid communication with a fluid dispensing device configured to
dispense charged and/or mixed fluids to vessels, such as, for
example, eppendorf tubes, vials, beakers, flasks, centrifuge tubes,
capillary tubes, cryogenic vials, bags, channels, cups, containers,
microtiter plates, microcards, and the like. The transport of
charged fluids from the fluid vessel to other vessels may be
accomplished, for example, using pumps, hydrostatic pressure,
capillary forces, and the like.
[0069] In various embodiments, the fluid charging systems disclosed
herein may be used to provide charged fluid to microfluidic
processing networks and systems. A charged fluid may be mixed with
other fluids in a microfluidic processing network or system.
Microfluidic processing networks and systems in which fluids may be
mixed are described, for example, in United States Patent
Application Publication Nos. 2005/0092681, 2005/0272144,
2008/0277494, 2010/0015606, 2010/0029512, 2010/0109320, and
2010/0297748, which are all incorporated by reference herein. The
fluid charging systems disclosed herein may be in fluid
communication with microfluidic processing networks and systems
such as those described in these documents.
[0070] In various embodiments, the fluid charging systems disclosed
herein may be used to provide charged fluid to microfluidic
processing networks and systems comprising liquid bridges. United
States Patent Application Publication Nos. 2008/0277494,
2010/0015606, 2010/0029512, 2010/0109320, and 2010/0297748, which
are all incorporated by reference herein, describe microfluidic
processing networks and systems comprising liquid bridges. A liquid
bridge is a device in which liquid droplets are formed. The
droplets formed in a liquid bridge are enveloped in an immiscible
carrier fluid. Generally, a liquid bridge is formed by an inlet in
communication with a chamber that is filled with immiscible carrier
fluid. The carrier fluid is immiscible with fluid droplets flowing
through the inlet into the chamber. The fluid droplets expand until
they are large enough to span a spatial gap between the inlet and
an outlet in communication with the chamber. Droplet formation is
accomplished, for example, by adjusting flow rate or by joining one
or more additional fluid droplets to a first fluid droplet,
resulting in formation of an unstable liquid bridge between the
inlet and the outlet that subsequently ruptures from the inlet.
After rupturing from the inlet, the fluid droplet enters the
outlet, surrounded by the carrier fluid from the chamber. In some
embodiments, the liquid bridge creates a droplet and also merges
that droplet with other droplets in the liquid bridge. In some
embodiments, droplets are formed using the autosampler previously
described. After the droplet is formed, it may be then carried to
the liquid bridge where it is then combined with other droplets,
such as for example master mix, sample, or any other suitable fluid
droplet.
[0071] The fluid charging systems disclosed herein may be
configured to provide charged fluid to a liquid bridge. For
example, a fluid sampling device of a fluid charging system may be
in fluid communication with a liquid bridge. In various
embodiments, a liquid bridge may be configured to segment a charged
fluid into droplets. In various embodiments, a liquid bridge may be
configured to mix droplets of charged fluid with droplet of other
fluid (that may be uncharged or charged, for example, as described
herein) that is miscible with the charged fluid. As used herein,
the term "droplet" refers to a relatively small microfluidic
quantity or plug of liquid as it is suspended and/or flows in an
immiscible carrier liquid in a conduit or chamber, such as, for
example, in a microfluidic processing network or system.
[0072] In various embodiments, a liquid bridge configured to
segment charged fluid withdrawn from a fluid vessel into droplets
comprises a first inlet port in fluid communication with a fluid
sampling device, a second inlet port in fluid communication with a
source of immiscible fluid, an outlet port, and a chamber. The
inlet ports and the outlet port open into the chamber and may be
structured and positioned so that fluid instability in fluid
droplets formed between the first inlet port and the outlet port
segments the fluid withdrawn from the fluid vessel into fluid
droplets separated by the immiscible fluid. The fluid droplets may
be withdrawn from the chamber through the outlet port.
[0073] In various embodiments, a liquid bridge configured to mix
charged fluid withdrawn from a fluid vessel in a fluid charging
system with one or more additional fluids that may be miscible with
the charged fluid comprises a first inlet port in fluid
communication with the fluid sampling device, one or more
additional inlet ports in fluid communication with sources of the
one or more additional fluids, an outlet port, and a chamber. The
inlet ports and the outlet port open into the chamber and may be
structured and positioned so that first fluid droplets formed at
the first inlet port contact and mix with one or more additional
fluid droplets formed at the one or more additional inlet ports,
thereby forming unstable funicular bridges of mixed fluid. The
unstable funicular bridges rupture, thereby forming mixed fluid
droplets separated by immiscible carrier fluid that are withdrawn
from the chamber through the outlet port. The net charge carried by
the fluid withdrawn from the fluid vessel improves the mixing of
the charged fluid with the one or more additional fluids.
[0074] In various embodiments, a liquid bridge configured to mix
charged fluid withdrawn from a fluid vessel in a fluid charging
system with one or more additional fluids that are miscible with
the charged fluid comprises a chamber, one or more inlet ports, a
first outlet port, and a second outlet port. The inlet ports and
the outlet ports may open into the chamber. An inlet port may be in
fluid communication with a fluid sampling device and sources of one
or more additional fluids. The inlet ports may serially provide
fluid droplets of the charged fluid withdrawn from the fluid vessel
and the one or more additional fluids, wherein the droplets may be
separated by an immiscible carrier fluid. The first outlet port may
be configured to withdraw a portion of the immiscible carrier fluid
entering the chamber. The inlet ports and the outlet ports may be
structured and positioned so that trailing droplet transporting
through the inlet port contact and mix with leading droplets formed
at the inlet port in the chamber, thereby forming mixed fluid
droplets that may be withdrawn from the chamber through the second
outlet port separated by immiscible carrier fluid. The net charge
carried by the fluid withdrawn from the fluid vessel improves the
mixing of the charged fluid with the one or more additional
fluids.
[0075] Further description of the structure and operation of
segmenting liquid bridges and mixing liquid bridges is presented in
United States Patent Application Publication Nos. 2008/0277494 and
2010/0029512, which are incorporated by reference herein.
[0076] In various embodiments, the fluid charging systems and
methods disclosed herein may be used to mix reagents for a
polymerase chain reaction (PCR) process, such as, for example, a
quantitative PCR (Q-PCR) process, a digital PCR (dPCR) process, or
a genotyping PCR (gPCR) process. PCR is a technique for the
amplification of DNA samples. Q-PCR, for example, is a variant of
PCR in which the amplification of DNA samples can be quantified to
obtain data on the amount of DNA in a sample. A typical PCR
reaction, such as, for example, a Q-PCR, dPCR, or gPCR reaction,
contains reactants including: fluorescent double-stranded binding
dye; Taq polymerase; deoxynucleotides of type A, C, G, and T;
magnesium chloride; forward and reverse primers; and subject DNA.
These reactants are all suspended within an aqueous fluid buffer.
Reactants, however, may be assigned into two broad groups:
universal reactants and reaction-specific reactants. Universal
reactants are those common to most PCR reaction, and include:
fluorescent double-stranded binding dye; Taq polymerase;
deoxynucleotides A, C, G, and T; and magnesium chloride.
Reaction-specific reactants include the forward and reverse primers
and subject DNA. In various applications, it may be desirable to
mix microfluidic quantities of universal reactants and
reaction-specific reactants.
[0077] In various embodiments, a master mixture of universal PCR
reactants may be charged using a fluid charging device, system, or
method as disclosed herein. A fluid vessel in a fluid charging
system may contain a master mixture of universal PCR reactants. A
fluid sampling device may withdraw charged master mixture fluid.
The charged master mixture fluid may be mixed in a downstream
operation with one or more additional fluids comprising samples
and/or reaction-specific reactants. For example, a mixing liquid
bridge or other mixing microfluidic system may be in fluid
communication with a fluid sampling device configured to withdraw
charged master mixture and in fluid communication with a source of
fluid comprising reaction-specific reactants. The net charge
carried by the master mixture may improve the mixing of the master
mixture with the fluid, thereby achieving a more homogeneous
suspension of universal and reaction-specific PCR reactants in an
aqueous buffer fluid.
[0078] In various embodiments, a fluid sampling device may be in
fluid communication with a vessel, conduit, or channel in a thermal
cycler device for performing amplification reactions according to a
PCR technique. In various embodiments, a fluid sampling device may
be in fluid communication with a thermal cycler device configured
to perform continuous-flow PCR, such as, for example, the devices
described in United States Patent Application Publication Nos.
2008/0280331, 2010/009273, 2010/0092987, and 2010/0304446, which
are all incorporated by reference herein. In various embodiments,
the fluid communication between a fluid sampling device and a
vessel or conduit in a thermal cycler device may be provided by a
microfluidic processing network or system, which may comprise one
or more liquid bridges.
[0079] Liquid bridge systems can be fluidly connected, e.g., by
tubes or channels, to any type of analysis device. In various
embodiments, a liquid bridge microfluidic system connects a fluid
charging system to a thermal cyler to perform PCR reactions on a
DNA sample. An exemplary thermal cycler and methods of fluidly
connecting a thermal cycler to a liquid bridge system are described
in International Patent Application Publications Nos. WO
2005/023427, WO 2007/091230, and WO 2008/038259, which are
incorporated by reference herein. A thermal cycler may be connected
to an optical detecting device to detect the products of a PCR
reaction. An optical detecting device and methods for connecting
the device to the thermal cycler are described in International
Patent Application Publications Nos. WO 2007/091230 and WO
2008/038259, which are incorporated by reference herein.
[0080] Further provided herein is a method of mixing droplets using
electrostatic charging of droplets. In some embodiments a charged
droplet, for example a statically charged droplet, may be directed
toward a second droplet. The second droplet may be charged or
uncharged. As the charged droplet approaches the second droplet,
the charged droplet may induce charge separation, or further induce
charge separation, in the awaiting second droplet. The charge
separation may then cause the charged droplet and the second
charged or uncharged droplet to become more attracted to each other
and thereby may facilitate the combining of the two droplets.
Additionally, the charge separation induced in the second droplet,
together with the charge of the charged droplet may cause the two
droplets to mix in a more efficient manner than when both droplets
are uncharged. In some embodiments, a charged droplet may be
combined with at least two droplets, which may be charged or
uncharged, to form a charged droplet.
EXAMPLES
Example 1
[0081] A fluid charging system is provided for charging fluids to
be mixed with other fluids in a microfluidic system. The system
includes a Fraser Model 7330 static generator connected to an
ionizing electrode assembly via a high voltage cable. The ionizing
electrode assembly includes a cross-shaped electrode comprising a
cross-shaped stainless steel emitter plate and five (5) tungsten
emitter pins. The ionizing electrode is connected to a 100 megaohm
resistor unit via a high voltage lead. The ionizing electrode
assembly has the dimensions and configuration shown in FIG. 20
(dimensions in millimeters). A ground electrode comprises a
circular aluminum static ground plate that sits in a non-conductive
acrylic holder. The ground electrode has the dimensions and
configuration shown in FIGS. 21a, 21b, and 21c (dimensions in
millimeters). The ground electrode is connected to the ground lug
on the static generator.
[0082] The static generator uses solid state electronics and high
frequency switching technology to provide stable electrical power
output under a controlled current mode (up to 1.1 milliamps) or a
controlled voltage mode (up to 20 kilovolts) from a 24 VDC supply.
The static generator has a 0-10V analog controller input that is
interfaced with a remote PC running a LabVIEW.TM. control program
(National Instruments Corporation, http://www.ni.com/). The static
generator and the remote PC are interfaced through a printed
circuit board (PCB) having digital-to-analog conversion capability.
FIGS. 22 and 23 show a circuit diagram and board layout,
respectively, of the PCB interfacing the static generator and
remote PC.
[0083] FIG. 24 shows the ionizing electrode and the ground
electrode positioned adjacent to a glass fluid vessel. The ionizing
electrode and the ground electrode are opposed so that the fluid
vessel is positioned between the ionizing electrode and the ground
electrode. The glass fluid vessel has an outer diameter that
substantially matches the diameter of the ground electrode, the
ground electrode and holder being dimensioned to seat and support
the fluid vessel. Four (4) fluid sampling devices are positioned
through open quadrant regions of the emitter plate of the ionizing
electrode. The four (4) fluid sampling devices include sheaths
surrounding tubes configured to withdraw fluid from the fluid
vessel.
Example 2
[0084] The fluid charging system described in Example 1 is used to
charge a first fluid. The fluid charging system described in
Example 1 provides the first fluid with a net positive charge. The
four (4) fluid sampling devices withdraw charged first fluid from
the fluid vessel. The four (4) fluid sampling devices are in fluid
communication with a microfluidic network including liquid bridges
as described, for example, in United States Patent Application
Publication Nos. 2008/0277494, 2010/0015606, 2010/0029512,
2010/0109320, and 2010/0297748, which are all incorporated by
reference herein. The charged first fluid is mixed with one or more
additional fluids in a liquid bridge. The charged first fluid and
the one or more additional fluids are miscible. The net positive
charge improves the mixing of the first fluid with the one or more
additional fluids in the liquid bridge.
Example 3
[0085] The fluid charging system described in Example 1 is used to
charge a first fluid comprising a master mixture. The fluid
charging system described in Example 1 provides the first fluid
with a net positive charge. The four (4) fluid sampling devices
withdraw charged fluid comprising master mixture from the fluid
vessel. The four (4) fluid sampling devices are in fluid
communication with a microfluidic network including liquid bridges
as described, for example, in United States Patent Application
Publication Nos. 2008/0277494, 2010/0015606, 2010/0029512,
2010/0109320, and 2010/0297748, which are all incorporated by
reference herein. The charged fluid comprising the master mixture
is mixed with two additional fluids in a liquid bridge. The two
additional fluids comprise DNA samples and reaction-specific
reactants and are miscible with the charged fluid comprising the
master mixture. The net positive charge improves the mixing of the
first fluid with the two additional fluids in the liquid
bridge.
[0086] The mixed fluid comprising the master mixture, DNA sample,
and reaction-specific reactants is used to perform an amplification
reaction. The liquid bridges are in fluid communication with a
thermal cycler device configured to perform continuous-flow PCR,
such as, for example, the devices described in United States Patent
Application Publication Nos. 2008/0280331, 2010/009273,
2010/0092987, and 2010/0304446, which are all incorporated by
reference herein. The mixed fluid comprising the master mixture,
DNA sample, and reaction-specific reactants is microfluidically
transported to the thermal cycler device where the PCR
amplification reactions are performed.
Example 4
[0087] A negatively charged droplet may be formed as follows. An
electrostatic pinner bar (SIMCO) is positioned above the master mix
well creating a large electric field across the well. A voltage of
12-18 kV is typically applied across a distance of 50-80 mm. This
has the effect of creating a differing charge density within the
aqueous solution. Using a positive charge-generator produces a much
higher concentration of negative ions at the top of the well. Since
some enzymes, for example Taq enzymes, are neutrally charged, the
enzyme remains unaffected by the charge separation. When a droplet
is removed from the well, the fluid removed is from the upper
negatively charged aqueous region resulting in a highly negatively
charged droplet.
[0088] This specification has been written with reference to
various non-limiting and non-exhaustive embodiments. However, it
will be recognized by persons having ordinary skill in the art that
various substitutions, modifications, or combinations of any of the
disclosed embodiments (or portions thereof) may be made within the
scope of this disclosure. Thus, it is contemplated and understood
that the present disclosure embraces additional embodiments not
expressly set forth herein. Such embodiments may be obtained, for
example, by combining, modifying, or reorganizing any of the
disclosed steps, components, elements, features, aspects,
characteristics, limitations, and the like, of the various
embodiments described herein. In this manner, Applicants reserve
the right to amend the claims during prosecution to add features as
variously described herein in compliance with the requirements of
35 U.S.C. .sctn.112, first paragraph, and 35 U.S.C.
.sctn.132(a).
* * * * *
References