U.S. patent application number 14/777505 was filed with the patent office on 2016-10-13 for systems and methods for active particle separation.
The applicant listed for this patent is ANCERA, INC.. Invention is credited to Hur KOSER.
Application Number | 20160296945 14/777505 |
Document ID | / |
Family ID | 51538374 |
Filed Date | 2016-10-13 |
United States Patent
Application |
20160296945 |
Kind Code |
A1 |
KOSER; Hur |
October 13, 2016 |
SYSTEMS AND METHODS FOR ACTIVE PARTICLE SEPARATION
Abstract
A device and method for extracting particles contained in a
ferrofluid medium are provided. Such methods may comprise
suspending particles of different sizes in a ferrofluid medium and
containing the ferrofluid medium in a cylindrical reservoir, and
applying a first magnetic field to at least a portion of the
reservoir. The first magnetic field is configured to indirectly
exert a force on at least a portion of the particles of a
predetermined size, and direct the portion of particles in a
desired direction.
Inventors: |
KOSER; Hur; (Branford,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ANCERA, INC. |
Branford |
CT |
US |
|
|
Family ID: |
51538374 |
Appl. No.: |
14/777505 |
Filed: |
March 14, 2014 |
PCT Filed: |
March 14, 2014 |
PCT NO: |
PCT/US14/29336 |
371 Date: |
September 15, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61794885 |
Mar 15, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B03C 1/0332 20130101;
B03C 1/288 20130101; G01N 35/0098 20130101; B03C 1/32 20130101;
B03C 1/0335 20130101; C12N 13/00 20130101; B03C 1/023 20130101;
C02F 1/488 20130101; C02F 1/44 20130101; B03C 2201/26 20130101;
B03C 1/253 20130101; B03C 2201/18 20130101 |
International
Class: |
B03C 1/32 20060101
B03C001/32; C12N 13/00 20060101 C12N013/00; C02F 1/48 20060101
C02F001/48; B03C 1/28 20060101 B03C001/28; C02F 1/44 20060101
C02F001/44 |
Claims
1. A method for extracting particles contained in a ferrofluid
medium, the method comprising: suspending particles of different
sizes in a ferrofluid medium and containing the ferrofluid medium
in a cylindrical reservoir; applying a first magnetic field to at
least a portion of the reservoir, wherein the first magnetic field
is configured to: indirectly exert a force on at least a portion of
the particles of a predetermined size, and direct the portion of
particles in a desired direction.
2. The method of claim 1, wherein applying the first magnetic field
includes surrounding at least the portion of the reservoir with the
magnetic field.
3. The method of claim 1, wherein the particles comprise at least
one of biological cells and moieties.
4. The method of claim 1, where the reservoir includes or is in
communication with an extraction opening.
5. The method of claim 4, wherein the desired direction is toward
the extraction opening.
6. The method of claim 4, wherein the desired direction is away
from the extraction opening.
7. The method of claim 1, wherein the desired direction is toward a
central axis of the reservoir.
8. The method of claim 1, wherein the desired direction is away
from a central axis of the reservoir.
9. The method of claim 1, wherein the predetermined size comprises
smaller particles relative to the remainder of the particles in the
ferrofluid medium.
10. The method of claim 1, wherein the predetermined size comprises
larger particles relative to the remainder of the particles in the
ferrofluid medium.
11. The method of claim 1, wherein a flow outlet is provided on
and/or in communication with the reservoir.
12. The method of claim 11, wherein the exerted force is configured
such that the portion of particles is carried away in a flow out of
the reservoir via the flow outlet.
13. The method of claim 12, further comprising applying an external
force on the reservoir to establish the flow out the flow
outlet.
14. The method of claim 13, wherein the external force is applied
via a pressure source.
15. The method of claim 14, wherein the pressure source is a
pump.
16. The method of claim 5, further comprising accelerating a flow
of the portion of particles via a second magnetic field, the second
magnetic field generated by a second magnetic field source arranged
on a portion of the reservoir positioned opposite to the extraction
opening.
17. The method of claim 1, further comprising providing a membrane
within the reservoir.
18. The method of claim 17, wherein the membrane comprises a
non-magnetic membrane configured with pore sizes larger than
particles within the reservoir to direct particles in a second
desired direction.
19. The method of claim 18, wherein the second desired direction is
toward spaces between pores of the membrane, wherein the spaces are
configured to retain particles of at least a first size.
20. The method of claim 18, wherein the second desired direction is
toward pores of the membrane, such that the particles pass through
the membrane.
21. The method of claim 18, wherein the non-magnetic membrane
comprises a plastic sheet.
22. The method of claim 18, wherein the membrane is configured to
reduce the amplitude of or substantially eliminate the first
magnetic field or the effects thereof.
23. The method of claim 22, wherein the amplitude is selected based
on the size of the portion of the particles.
24. The method of claim 18, further comprising a plurality of
non-magnetic beads suspended in the ferrofluid, the non-magnetic
beads being functionalized with at least one predetermined receptor
configured to bind with a target particle contained in the
particles within the ferrofluid medium.
25. The method of claim 24, wherein the at least one predetermined
receptor include at least one of a molecule, a cell, an antibody,
DNA or fragment thereof, and a ligand.
26. The method of claim 24, wherein the first magnetic field is
configured to direct target particles toward space between pores of
the membrane which are configured to retain the target
particles.
27. method of claim 26, further comprising detecting means to at
least one of track or count the retained target particles.
28. The method of claim 17, further comprising providing at least
one other nonmagnetic membrane, wherein the at least one other
non-magnetic membrane is parallel to other membranes.
29. The method of claim 28, wherein each membrane has a smaller
pore size than a previous membrane.
30. The method of claim 17, wherein the membrane comprises a
magnetic membrane.
31. The method of claim 30, wherein the magnetic membrane comprises
a thin foil of nickel.
32. The method of claim 30, further comprising providing a
plurality of magnetic beads suspended in the ferrofluid medium, the
magnetic beads being functionalized with at least one predetermined
receptor configured to bind with a target particle contained in the
particles within the ferrofluid medium.
33. The method of claim 32, wherein the magnetic beads are directed
toward a surface of the magnetic membrane between the pores.
34-60. (canceled)
Description
RELATED APPLICATIONS
[0001] This application claims benefit under 35 USC 119(e) of U.S.
provisional patent application Nos. 61/794,885, filed Mar. 15,
2013, and entitled, "PCB-Based Magnetic Excitation Approach" the
entire disclosure of which is herein incorporated by reference in
its entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to methods and systems for
extracting particles from ferrofluids.
BACKGROUND OF THE DISCLOSURE
[0003] WO2011/071912 and WO2012/057878 presents systems and methods
for separating microparticles or cells contained in a ferrofluid
medium using magnetic forces. The magnitude of these forces depend,
in part, on the volume of the non-magnetic particles (e.g.,
moieties) for separation/targeting. Moreover, a larger cell or
microparticle displaces a larger ferrofluid volume, and experiences
larger forces.
[0004] Mechanical exclusion, via well-known filtration is, by its
very nature, prone to clogging, and also subsequent increases in
pressure drop across the filter as the filter becomes more and more
clogged. Such filtration means rely on physically stopping a large
enough target particle across a smaller opening on a surface.
SUMMARY OF THE DISCLOSURE
[0005] Embodiments of this disclosure are a further application and
development of previous series of disclosures, including, for
example PCT publication no. WO2011/071912 and WO2012/057878, the
noted disclosures of which are all herein incorporated by reference
in their entireties.
[0006] In some embodiments, methods for extracting particles
contained in a ferrofluid medium are provided. Such methods may
comprise suspending particles of different sizes in a ferrofluid
medium to form a mix and containing the mix in a reservoir (e.g.,
cylindrical), and applying a first magnetic field to at least a
portion of the reservoir. The first magnetic field is configured to
indirectly exert a force on at least a portion of the particles of
at least one predetermined size and/or shape, and direct the
portion of particles in a desired direction.
[0007] Such method embodiments may additionally include one or more
(or all, as applicable) of the following features (thereby
establishing yet other embodiments): [0008] applying includes
surrounding at least the portion of the reservoir with the magnetic
field; [0009] the particles comprise at least one of biological
cells and moieties; [0010] the reservoir includes or is in
communication with an extraction opening; [0011] the desired
direction is toward the extraction opening; [0012] the desired
direction is away from the extraction opening; [0013] the desired
direction is toward a central axis the reservoir; [0014] the
desired direction is away from a central axis of the reservoir;
[0015] the predetermined size comprises smaller particles relative
to the remainder of the particles in the ferrofluid medium; [0016]
the predetermined size comprises larger particles relative to the
remainder of the particles in the ferrofluid medium; [0017] a flow
outlet is provided on and/or in communication with the reservoir;
[0018] the exerted force is configured such that the portion of
particles are carried away in a flow out of the reservoir via the
flow outlet; [0019] applying an external force on the reservoir to
establish the flow out the flow outlet, where; [0020] the external
force is applied via a pressure source, where the pressure source
is a pump; [0021] accelerating a flow of the portion of particles
via a second magnetic field, the second magnetic field generated by
a second magnetic field source arranged on a portion of the
reservoir positioned opposite to the extraction opening; [0022] a
non-magnetic membrane configured with pore sizes larger than
particles within the reservoir to direct particles in a second
desired direction; [0023] the second desired direction is toward
spaces between the pores of the membrane, wherein the membrane
spaces are configured to retain the particles; [0024] the second
desired direction is toward the pores of the membrane, such that
the particles pass through the membrane; [0025] the non-magnetic
membrane comprises a plastic sheet; [0026] the first magnetic field
source is configured to reduce the amplitude or substantially
eliminate the first magnetic field or the effects thereof; [0027]
the amplitude is selected based on the size of the size of the
portion of the particles; [0028] a plurality of non-magnetic beads
suspended in the ferrofluid, the non-magnetic beads being
functionalized with at least one predetermined receptor configured
to bind with a target particle; [0029] wherein the at least one
predetermined receptor include at least one of a molecule, a cell,
an antibody, DNA or fragment thereof, and a ligand; [0030] the
magnetic field is configured to direct the target particles toward
the space between the pores of the membrane which are configured to
retain the target particles; and [0031] detecting means to at least
one of track or count the retained target particles.
[0032] In some embodiment of the disclosure, systems for extracting
particles contained in a biocompatible ferrofluid medium are
provided. Such systems may comprise a reservoir (e.g., cylindrical)
configured to contain a ferrofluid medium containing particles of
different sizes to form a mix, a first magnetic field source
configured to indirectly exert a force on the particles to direct
at least a portion of the particles of at least one size and/or
shape in a desired direction, and an extraction opening arranged on
a portion of the reservoir and/or in communication with the
reservoir, the extraction opening configured to receive particles
of at least one size and/or shape (may be predetermined size and/or
shape) from the reservoir as a result of the exerted force.
[0033] Such system embodiments, may include one or more (or all, as
applicable) of the following additional features (thereby
establishing yet other embodiments): [0034] the first magnetic
field source is configured to generate a first magnetic field
surrounding at least the portion of the reservoir; [0035] the
particles comprise at least one of biological cells and moieties;
[0036] the desired direction is toward the extraction opening;
[0037] the desired direction is away from the extraction opening;
[0038] the desired direction is toward a central axis of the
reservoir; [0039] the desired direction is away from a central axis
of the reservoir; [0040] the predetermined size comprises smaller
particles relative to the remainder of the particles in the
ferrofluid medium; [0041] the predetermined size comprises larger
particles relative to the remainder of the particles in the
ferrofluid medium; [0042] a flow outlet provided on and/or in
communication with the reservoir; [0043] the exerted force is
configured such that the portion of particles are carried away in a
flow out of the reservoir via the flow outlet, and wherein the
desired direction is away from the extraction opening; [0044]
applying a non-magnetic external force on the reservoir to
establish the flow out the flow outlet; [0045] the external force
is applied via a pressure source, where the pressure source is a
pump; and [0046] a second magnetic field source arranged on a
portion of the reservoir located opposite to the extraction
opening, the second magnetic field source configured to generate a
second magnetic field on the portion of the particles to accelerate
a flow of the portion of particles to the extraction opening;
[0047] a non-magnetic membrane configured with pore sizes larger
than particles within the reservoir to direct particles in a second
desired direction; [0048] the second desired direction is toward
spaces between the pores of the membrane, wherein the membrane
spaces are configured to retain the particles; [0049] the second
desired direction is toward the pores of the membrane, such that
the particles pass through the membrane; [0050] the non-magnetic
membrane comprises a plastic sheet; [0051] the first magnetic field
source is configured to reduce the amplitude or substantially
eliminate the first magnetic field or the effects thereof; [0052]
the amplitude is selected based on the size of the size of the
portion of the particles; [0053] a plurality of non-magnetic beads
suspended in the ferrofluid, the non-magnetic beads being
functionalized with at least one predetermined receptor configured
to bind with a target particle; [0054] the at least one
predetermined receptor include at least one of a molecule, a cell,
an antibody, DNA or fragment thereof, and a ligand; [0055] the
magnetic field is configured to direct the target particles toward
the space between the pores of the membrane which are configured to
retain the target particles; and [0056] detecting mean to at least
one of track or count the retained target particles (such detecting
means being well known in the art).
[0057] The above-noted embodiments, as well as other embodiments,
will become even more evident with reference to the following
detailed description and associated drawing, a brief description of
which is provided below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] FIG. 1 is an illustration depicting structures of a
reservoir and associated structures containing a ferrofluid and a
mixture of microparticles, according to some embodiments.
[0059] FIG. 2 is an illustration depicting structures of a
reservoir and associated structures containing a ferrofluid and a
mixture of microparticles, including a magnetic source for applying
a magnetic field to the reservoir, according to some
embodiments.
[0060] FIG. 3 is an illustration depicting structures of a
reservoir and associated structures containing a ferrofluid and a
mixture of microparticles, including two magnetic sources for
applying one or more magnetic fields to the reservoir, according to
some embodiments.
[0061] FIG. 4 is an illustration depicting structures of a membrane
with pore sizes larger than the individual particles/cells placed
within a reservoir containing a ferrofluid medium.
[0062] FIG. 5 is an illustration depicting the cross-sectional and
schematic view of a membrane with pores within a ferrofluid
medium.
DETAILED DESCRIPTION OF SOME OF THE EMBODIMENTS
[0063] As shown in FIG. 1, a reservoir 10 containing a ferrofluid
11 (which in some embodiments is biocompatible) and a mixture of
microparticles/cells 12 having different sizes (in some
embodiments). In FIG. 1, no external forces are applied to the
fluid, reservoir and/or particles, and ignoring buoyancy issues, a
random mixture of particles may flow through an extraction opening
13 of the reservoir.
[0064] FIG. 2 illustrates some embodiments, where a reservoir 20
containing a ferrofluid 21 with a mixture of microparticles 22 of
different sizes, and includes at least one magnetic source 25 for
applying a magnetic field to the ferrofluid 21, which may be
arranged either internal or external to the reservoir 20. The
particles 22 include biological cells and moieties. The magnetic
field may be configured to exert one or more forces on the
ferrofluid 21 and may be generated via, for example, one or more:
external magnets, current-carrying electrodes, solenoid, and
electromagnets. In one embodiment, the magnetic field may surround
at least a portion of the reservoir 20. The reservoir 10 includes
or is in communication with an extraction opening 23. The force(s)
exerted by the magnetic fields on the ferrofluid 21 cause the
particles 22, in some embodiments, to be directed in a desired
direction. Such a desired direction may be toward the extraction
opening 23, away from the extraction opening 23, toward a central
axis of the reservoir 20, and away from a central axis of the
reservoir 20, according to some embodiments. The particles 22
include, in one embodiment, smaller particles relative to the
remainder of the particles 22 in the ferrofluid 21 and larger
particles relative the remainder of the particles 22 in the
ferrofluid 21. The larger particles feel much larger repulsive
forces, and can hence be dynamically levitated above the outlet,
whereas the smaller particles will be dragged out with flow. In one
embodiment, a flow outlet 24 is provided on and/or in communication
with the reservoir. The exerted force may be configured to carry
away a portion of particles 22 in a flow out of the reservoir 20
via the flow outlet 24. Such a flow out of the reservoir 20 may be
generated via an external force, for example, a pressure source or
a pump.
[0065] It is possible to create a magnetic field pattern around a
sample reservoir or vial carrying microparticles or cells suspended
within a biocompatible ferrofluid in order to push those moieties
either toward or away from an extraction hole. This approach and
the device that achieves this manipulation could be used in the
context of either speeding or delaying the delivery of the target
moieties from the volume of the reservoir into the fluidic
cartridge downstream. The magnitude of this magnetic force would
depend in part on the intensity of the magnetic field sources, as
well as their relative geometry with respect to that of the
reservoir. The magnetic force also depends on the ferrofluid
susceptibility and the volume of the microparticles/cells. Hence,
the pushing force, in conjunction with the flow rate out of the
reservoir/vial into the extraction hole, could be engineered such
that moieties larger than a selectable threshold volume could be
continuously and dynamically repelled away the vial's outlet under
steady state conditions. In this fashion, moieties larger than the
selectable threshold volume could be excluded from the fluidic
network downstream.
[0066] What is described here is an "active pre-filter" that works
on dynamic magnetic exclusion principles in steady-state flow and
magnetic excitation conditions. Most other size-based filtration
methods rely on mechanical obstacles (such as pore sizes of a given
diameter in filter paper or micro fabricated devices) and work on
static mechanical exclusion principles.
[0067] The active pre-filter described here avoids the shortcomings
of mechanical filters by achieving size-based separation and
exclusion within the 3D volume of the vial/reservoir, instead of
the 2D surface of a mechanic filter (FIGS. 1 and 2). Those
microparticles or cells that are larger than the selectable
threshold are continuously suspended and mixed in the biocompatible
ferrofluid, hence preventing large scales of clustering and
possible clogging issues.
[0068] Even if the filtered moieties tend to cluster within the
ferrofluid, their increased overall hydrodynamic diameter will
result in substantially larger repulsion forces on them. With flow
drag roughly proportional to the hydrodynamic diameter (.about.d)
and magnetic forces proportional to the hydrodynamic volume
(.about.d.sup.3), the larger cluster will be pushed further away
from the outlet. Hence, this active pre-filter features a negative
feedback mechanism that naturally prevents potential clogging
issues (FIG. 2).
[0069] FIG. 3 illustrate some embodiments, where a reservoir 30
containing a ferrofluid 31 and a mixture of microparticles 32 with
different sizes. A second magnetic field source 36 maybe place
opposite the extraction opening 33 to accelerate the transport of
microparticles 32 towards it. In this fashion, the effect of any
other forces (such as buoyancy) on the delivery efficiency of
target particles/cells 32 to the fluidic network downstream may be
minimized. The larger particles would also cluster and levitate
closer to the outlet, the relative intensity of the two field
sources may be tuned to prevent any cluster from clogging the
outlet. Moreover, clusters may be broken by periodic intensity
modulations in at least one field sources.
[0070] It may be necessary to intentionally and periodically stir
up the contents of the vial so as to break up clusters of large
microparticles or cells. This will ensure that anything smaller
than the selection threshold is not impeded by or somehow stuck
within the clusters. This effect might be easily achieved by
modulating the intensity of the externally applied magnetic field
and allowing the flow to break the dynamic clusters apart (FIG.
3).
[0071] In the simplest realization of the active pre-filter, a
vial/reservoir with cylindrical symmetry sits on top of a tunable
source of magnetic fields, preferably encompassing similar symmetry
in its geometry. The magnetic field and its gradient are designed
to push the target moieties suspended in a biocompatible ferrofluid
up and towards the center of the vial, into the region of strongest
flow (away from the vial's interior surfaces). The biocompatible
ferrofluid is pulled into an extraction hole at the center bottom
of the vial via externally imposed flow conditions (e.g., a pump or
pressure device). The intensity of the magnetic field and its
gradient are engineered so as to push moieties larger than a
selectable size up and away from the vial's outlet at the bottom
faster than the maximum flow rate near the vicinity of the outlet.
In certain instances, a recirculation region within toroidal
symmetry is formed around the outlet, capturing and circulating the
filtered moieties. In other geometries, the filtered moieties hover
dynamically a certain distance over the outlet. In such cases, as
the filtration progresses, the filtered moieties are intentionally
allowed to cluster and pushed further up.
[0072] FIG. 4 illustrates some embodiments, where a reservoir 40
containing a ferrofluid 41 and a mixture of microparticles 42 with
different sizes. A first magnetic field source 45 placed proximate
to the extraction opening 43 and a second magnetic field source 46
placed opposite of the first magnetic field source 45 to accelerate
the transport of microparticles 42 toward the extraction opening
43.
[0073] In some embodiments, a non-magnetic membrane 47 configured
with pore sizes larger than microparticles 42 within the reservoir
40 containing the ferrofluid mix 41 of ferrofluid and target
particles is provided. Such membranes function to capture target
particles using magnetic fields. For example, in the absence of
externally applied magnetic fields, micro/target particles/cells
may flow through the membrane's pores. However, upon applying a
magnetic fields, the non-magnetic membrane 47 may be configured to
direct debris, particulate contaminants and microparticles/cells
42, larger than a size threshold value (for example), away from the
pores of the membrane and into the space between the pores.
Particles 42 smaller than the threshold, in some embodiments, tend
to follow flow streamlines and pass through the non-magnetic
membrane 47.
[0074] The non-magnetic membrane, in one embodiment, is made out of
a plastic sheet. In addition, in some embodiments, the pores may be
configured as any size (on a scale relative to the teachings
herein, e.g., pore sizes of 1-200 .mu.m, 5-50 .mu.m, 10-100 .mu.m,
20-30 .mu.m), and any shape, including, for example, round,
circular, polygonal, rectangular/slit, square, and/or elliptical.
In some embodiments, the shape of the pores is configured to aid in
the intended functionality of capturing particles using magnetic
forces and not by pore size (i.e., pore size relative to target
particle size), such that the overall pore size, in some
embodiments, is larger than the target particle size.
[0075] A plurality of pores, according to some embodiments, may be
arranged in predetermined patterns (i.e., not random), and may be
configured in such a manner to aid in the capture functionality of
the membrane feature. Thus, groups of pores on the same or
different size, shape, etc., may be arranged in repeated groups or
matrix. Such pores may be manufactured into a sheet of material,
by, for example, laser etching.
[0076] FIG. 5 illustrates some embodiments, magnetic field lines
prefer to stay within the magnetic medium of the ferrofluid. If the
porous membrane 50 is made out of a non-magnetic material (such as
a thin sheet of plastic), field lines traversing its thickness get
concentrated within the pores. This effect results in stronger
field amplitudes within the pores, compared to just outside
them--thereby creating a magnetic field gradient that pushes
particles up and away from the pores. Since the magnetic force on
particles is proportional to the volume of ferrofluid that they
displace, larger particles 51 tend to accumulate over the membrane
50 in the space between the spores, while small particles 52 follow
flow streamlines and pass through the membrane 50.
[0077] In some embodiments, the porous membrane may be made from a
thin foil of a magnetic material configured with a magnetic
susceptibility which is greater than that of the ferrofluid at the
magnetic excitation frequencies used (for example). For instance,
such magnetic membranes may be machined out of a thin foil of
nickel via, for example, lithographic etching or laser machining
Accordingly, upon the application of a magnetic field (e.g.,
external magnetic field), the magnetic field lines traversing the
thickness of the magnetic membrane tend to remain within the
membrane material. This effect, according to some embodiments, may
result in weaker field amplitudes within the pores compared to just
outside them, which thereby creates a magnetic field gradient that
can push the non-magnetic particles towards the pores. In some
embodiments, if magnetic beads are added to the sample mixture,
they may be attracted towards the surface of the magnetic membrane
between the pores. In this same fashion, functionalized magnetic
beads may be used to rapidly pull down, isolate and purify target
moieties in biocompatible ferrofluids.
[0078] The porous membrane is not absolutely necessary for the
active filter to function, but by creating strong and localized
field gradients, it allows for a much more robust and easily
tunable size-based separation.
[0079] When the fields are lowered in magnitude or turned off
completely, the retained particles/cells can be selectively
released back into the flow stream. For instance, in an assay that
is conducted with a mixture of whole blood and blood-compatible
ferrofluid, platelets, red blood cells and white blood cells may be
sequentially retained and selectively entered into the assay
channels by reducing the magnetic field amplitude appropriately for
each cell size. Hence, with the use of the active pre-filter,
labor- and time-intensive cell separation techniques (such as
centrifugation) may be rendered redundant, resulting in much
quicker and simpler assay protocols. The field magnitudes may be
sequentially controlled and timed by a microprocessor as part of an
automated assay.
[0080] In yet another embodiment, multiple membranes may be stacked
serially along the fluidic pathway, and may be exposed to the same
magnetic field sources (for example). Each membrane may be
positioned parallel to others in the stack and, in some
embodiments, at least partially orthogonal to the flow direction.
In some embodiments, a minimum spacing between each membrane is
chosen to correspond to at least their thickness, so that field
line density has space to return to normal between each membrane
(i.e., in some embodiments, this is provided to avoid one membrane
from interfering with the filtering ability of its neighbor). In
some embodiments, using stacked, non-magnetic membranes with
progressively smaller pore sizes, a complex mixture with various
cell/particle sizes (such as whole blood) may be fractionated very
rapidly based on size.
[0081] In some embodiments, the porous membrane may be used to
rapidly immobilize and hold down functionalized beads over its
surface. These beads would carry at least one kind of receptor
molecule, antibody, DNA fragment and other ligand on their outer
surface. As the beads are held on the membrane with magnetic
fields, a mixture of target and non-target moieties may be flown
through the active filter and rapidly captured on the "carpet" of
beads sitting over the porous membrane. The target moieties may be
small molecules, proteins, complementary DNA fragments, viruses,
bacteria or even larger cells. Once the target moieties have been
captured on the beads and isolated from the initial mixture, they
could be either tagged and quantified directly on the porous
membrane, or be released into the assay chamber for further
processing and quantification. With this approach, what is normally
a lengthy and labor-intensive sample preparation, incubation and
isolation process can be reduced to an automatic and rapid step
within a simple instrument.
[0082] In some embodiments, actual bacteria and cells are held on
the porous membrane surface with magnetic fields, and can be
exposed to molecular tags, candidate drug molecules, antibodies or
other proteins, with the express purpose of dramatically
accelerating the incubation processes associated with binding
ligands to cellular surface biomarkers.
[0083] The porous membrane may also be functionalized with ligands
that capture the pathogens or cells held on its surface. This
approach is especially useful if it is desired to have target
pathogens or cells remain on the membrane surface while other
moieties present in the initial sample mixture are washed away when
the magnetic fields are turned down (such as in sample purification
or immune-sorbent assays). As such, the active filter not only
solves the mass transport limitations associated with incubation
steps in molecular or cellular assays, it also avoids the
labor-intensive washing steps that typically follow binding/capture
reactions.
[0084] Any and all references to publications or other documents,
including but not limited to, patents, patent applications,
articles, webpages, books, etc., presented in the present
application, are herein incorporated by reference in their
entirety.
[0085] Example embodiments of the devices, systems and methods have
been described herein. As noted elsewhere, these embodiments have
been described for illustrative purposes only and are not limiting.
Other embodiments are possible and are covered by the disclosure,
which will be apparent from the teachings contained herein. Thus,
the breadth and scope of the disclosure should not be limited by
any of the above-described embodiments but should be defined only
in accordance with claims supported by the present disclosure and
their equivalents. Moreover, embodiments of the subject disclosure
may include methods, systems and devices which may further include
any and all elements from any other disclosed methods, systems, and
devices, including any and all elements corresponding to target
particle separation, focusing/concentration. In other words,
elements from one or another disclosed embodiments may be
interchangeable with elements from other disclosed embodiments. In
addition, one or more features/elements of disclosed embodiments
may be removed and still result in patentable subject matter (and
thus, resulting in yet more embodiments of the subject disclosure).
Correspondingly, some embodiments of the present disclosure may be
patentably distinct from one and/or another reference by
specifically lacking one or more elements/features. In other words,
claims to certain embodiments may contain negative limitation to
specifically exclude one or more elements/features resulting in
embodiments which are patentably distinct from the prior art which
include such features/elements.
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