U.S. patent application number 13/269297 was filed with the patent office on 2012-02-02 for microfluidic device for simultaneously conducting multiple analyses.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Yoon-kyoung CHO, Beom-seok LEE, Jeong-gun LEE, Jong-myeon PARK.
Application Number | 20120028830 13/269297 |
Document ID | / |
Family ID | 39765221 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120028830 |
Kind Code |
A1 |
LEE; Beom-seok ; et
al. |
February 2, 2012 |
MICROFLUIDIC DEVICE FOR SIMULTANEOUSLY CONDUCTING MULTIPLE
ANALYSES
Abstract
Provided is a rotatable microfluidic device for conducting
simultaneously two or more assays. The device includes a platform
which can be rotated, a first unit which is disposed at one portion
of the platform and detects a target material from a sample using
surface on which a capture probe selectively binds to the target
material is attached, and a second unit which is disposed at
another portion of the platform and detects a target material
included in the sample by a different reaction from the reaction
conducted in the first unit.
Inventors: |
LEE; Beom-seok;
(Hwaseong-si, KR) ; CHO; Yoon-kyoung; (Suwon-si,
KR) ; PARK; Jong-myeon; (Seoul, KR) ; LEE;
Jeong-gun; (Seoul, KR) |
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
39765221 |
Appl. No.: |
13/269297 |
Filed: |
October 7, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12128981 |
May 29, 2008 |
|
|
|
13269297 |
|
|
|
|
Current U.S.
Class: |
506/9 ; 422/69;
436/501; 506/39 |
Current CPC
Class: |
B01L 2200/10 20130101;
B01L 2300/0806 20130101; B01L 2400/086 20130101; F16K 2099/0084
20130101; B01L 2300/0867 20130101; F16K 99/0001 20130101; G01N
35/00069 20130101; F16K 99/0019 20130101; F16K 99/0061 20130101;
B01L 2300/087 20130101; B01L 3/502753 20130101; B01L 2400/0409
20130101; B01L 2300/0636 20130101; F16K 99/004 20130101; B01L
2200/0684 20130101; B01L 2400/0677 20130101; F16K 99/0032 20130101;
B01L 3/502738 20130101; B01L 3/502723 20130101; B01L 2300/0803
20130101; B01L 3/502746 20130101; B01L 2400/084 20130101 |
Class at
Publication: |
506/9 ; 422/69;
436/501; 506/39 |
International
Class: |
C40B 30/04 20060101
C40B030/04; G01N 33/566 20060101 G01N033/566; C40B 60/12 20060101
C40B060/12; G01N 30/96 20060101 G01N030/96 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 4, 2007 |
KR |
10-2007-0054628 |
Claims
1. A microfluidic device for conducting two or more assays, the
device comprising: a platform; a first assay structure which is
disposed at one location of the platform and detects a first target
material in a sample, said first assay structure being provided
with a protein which selectively reacts with the first target
material; and a second assay structure which is disposed at another
location of the platform and detects a second target material in
the sample, said second assay structure being provided with a
reagent which selectively reacts with the second target material,
wherein each of the first and the second assay structures comprises
a microfluidic structure comprising a chamber and a channel for
connecting the chamber; and wherein the protein is different from
the reagent.
2. The device of claim 1, wherein the first assay structure
comprises: a detection probe which is included within the
microfluidic structure, selectively binds to the first target
material, and includes an optical signal revelation material,
wherein the protein is bound to a surface, and wherein the
microfluidic structure allows the protein, the sample, and the
detection probe to react upon mixing.
3. The device of claim 2, wherein the surface is selected from the
group consisting of an inner wall of one of the chambers,
microparticles, and a microarray.
4. A method of detecting two or more target materials in a sample
using a microfluidic device, the method comprising introducing a
sample to a microfluidic device, said microfludic device
comprising: a platform which can be rotated; a first assay
structure which is disposed at one location of the platform and
detects a first target material in a sample, said first assay
structure being provided with a protein which selectively reacts
with the first target material; and a second assay structure which
is disposed at another location of the platform and detects a
second target material in the sample, said second assay structure
being provided with a reagent which selectively reacts with the
second target material, wherein the protein is different from the
reagent; supplying the sample to both of the first assay structure
and the second first assay structure; and detecting the first
target material and the second target material.
5. The method of claim 4, wherein the first assay structure of the
microfluidic device further comprises a detection probe, said
detection probe selectively binding to the first target material
and including an optical signal revelation material, and wherein
the detecting the first target material comprises measuring the
optical signal emitted from the optical signal revelation material.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0001] This is Continuation of application Ser. No. 12/128,981
filed May 29, 2008, which claims the benefit of Korean Patent
Application No. 10-2007-0054628, filed on Jun. 4, 2007, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a rotatable microfluidic
device, and more particularly, to a rotatable microfluidic device
in which multiple analysis of a biological sample can be
simultaneously conducted.
[0004] 2. Description of the Related Art
[0005] A microfluidic structure that performs an independent
function in a microfluidic device generally includes chambers that
can contain a fluid, channels through which a fluid can flow, and
valves that can control the flow of fluid, and can be configured by
various combinations of the chambers, the channels, and the valves.
An apparatus manufactured by disposing the microfluidic structure
on a chip type substrate, so that experiments including several
steps of treatments and manipulations of biochemical reactions can
be performed on a small chip, is often referred to as a
lab-on-a-chip.
[0006] In order to transport a fluid in a microfluidic structure, a
driving pressure is necessary. The driving pressure can be
capillary pressure or pressure supplied by an additional pump.
Recently, a disk type microfluidic device in which a microfluidic
structure is disposed on a disk-shaped platform to transport a
fluid using centrifugal force and to perform a series of works has
been proposed, which is referred to as a Lab CD or a Lab-on-a-disk.
Efforts have been made to provide various disk types of
microfluidic devices that can rapidly and accurately perform
necessary work in a centrifugal force-based disk type platform.
[0007] Disk type microfluidic devices can be applied to various
kinds of pathological tests. Conventional pathological tests
require a lot of work and various kinds of equipment. In order to
rapidly perform a test, skilled clinical pathologists are required.
However, even if clinical pathologists have required skill, it is
difficult to perform various kinds of tests at the same time.
However, in a diagnosis of an emergency patient, a rapid test
result is very important for timely treatment of the patient. Thus,
there is a need to develop an apparatus that can rapidly and
accurately and simultaneously perform various pathological tests
according to the necessary situations.
SUMMARY OF THE INVENTION
[0008] The present invention provides a disc-shaped microfluidic
device in which an immunoassay and a biochemical analysis having
different processes can be simultaneously conducted and a
microfluidic system including the disc-shaped microfluidic
device.
[0009] The present invention provides a device in which several
kinds of test units simultaneously perform desired function when a
common process is involved in the function performed by different
test units and one test unit does not affect the operations of
other test units when a unique process for each test is performed
so that different pathological tests can be quickly and accurately
conducted within one disc-shaped microfluidic device.
[0010] According to an aspect of the present invention, there is
provided a microfluidic device for simultaneously conducting two or
more assays, the device comprising: a platform which can be
rotated; a first assay unit which is disposed at one portion of the
platform and detects a first target material from a biological
fluid sample, wherein the detecting the target material is carried
out using a surface ("capture probe-bound surface") to which a
capture probe which selectively binds to the target material is
attached; and a second assay unit which is disposed at another
portion of the platform and detects a second target material in the
biological fluid sample by a reaction using a reagent which reacts
with the second target material, wherein the reagent is previously
loaded in the second assay unit; wherein each of the first and
second units comprises a microfluidic structure which includes a
plurality of chambers, a plurality of channels for connecting the
plurality of chambers, and a plurality of valves for controlling
the flow of a fluid through the channels; and wherein the plurality
of valves comprise at least one phase transition valve comprising a
valve material in which heat-generating particles are dispersed in
a phase transition material that is in a solid state at a room
temperature and in a liquefied state at a temperature higher than
the melting point of the phase transition material, and the valve
material changing into a molten state, when energy is applied to
the heat-generating particles, resulting in opening or closing its
corresponding channel path.
[0011] The first unit may be an immunoassay unit and the second
unit may be a biochemical analysis unit. The first target material
and the second target material may be the same of different. In
embodiments of the present invention, the first target material is
different from the second target material, and thus different
target materials may be simultaneously assayed in one device.
[0012] According to another embodiment, there is provided a
disc-shaped microfluidic device for simultaneously conducting
immunoassay and biochemistry analysis, the device comprising: a
disc-shaped platform which can be rotated; an immunoassay unit
which is disposed at one portion of the disc-shaped platform and
detects a target material from a sample using surface on which a
capture probe selectively combined with the target material is
bound; and a biochemistry analysis unit which is disposed at
another portion of the disc-shaped platform and detects a target
material included in the sample by a biochemical reaction of the
sample and a previously-stored reagent, wherein each of the
immunoassay unit and the biochemistry analysis unit comprises a
microfluidic structure which includes a plurality of chambers, a
plurality of channels for connecting the plurality of chambers, and
a plurality of valves for controlling the flow of a fluid through
the channels, and the plurality of valves comprise at least one
phase transition valve comprising a valve material in which
heat-generating particles are dispersed in a phase transition
material that is in a solid state at room temperatures and in a
liquefied state at high temperatures, and the valve material
changing into a molten state by energy applied to the
heat-generating particles. The heat-generating particles generate
heat when an electromagnetic beam is radiated to them from an
external energy source, resulting in opening or closing
corresponding channel path.
[0013] The capture probe-bound-surface is provided by at least one
of surfaces of microparticles accommodated in the microfluidic
structure, a surface of a microarray chip mounted in the
microfluidic structure, and an inner surface of at least one of the
plurality of chambers.
[0014] The phase transition material may be at least one material
selected from the group consisting of wax, gel, and thermoplastic
resin. The heat-generating particles may have a diameter of 1 nm to
100 .mu.m. The heat generating particles may comprise a core which
absorbs an externally generated electromagnetic beam to change the
electromagnetic beam into a heat energy and a shell encompassing
the core. The heat generating particles may be at least one
selected from the group consisting of polymer beads, quantum dots,
Au nanoparticles, Ag nanoparticles, beads with metal composition,
carbon particles, and magnetic beads.
[0015] The immunoassay unit may comprise: microfluidic particles
which are included within the microfluidic structure and provide
the capture probe-bound-surface; and a detection probe which is
included within the microfluidic structure, is selectively combined
with the target material, and includes a material needed for
optical signal revelation, wherein the microfluidic structure
allows the microparticles, the sample, and the detection probe to
react by mixing them and cleans and separates the microparticles in
which the reaction is completed. The immunoassay unit may further
comprise a reagent which is included in the microfluidic structure,
is mixed with the cleaned and separated microparticles and reacts
with the optical signal revelation material of the detection probe
attached to the target material to generate an optical signal.
[0016] The phase transition valve may comprise: an opening valve
which is disposed so that a valve plug closes the path at an
initial stage, and which, when the valve plug is melted by heat,
moves to a drain chamber disposed to be adjacent to an initial
position of the valve plug so as to open the path; and a closing
valve which includes a valve chamber connected to the path and a
valve material inserted in the valve chamber in an initial state,
wherein if the valve material is melted and expands by heat, the
valve material enters the path, is solidified and closes the
path.
[0017] The microfluidic structure of the immunoassay unit may
comprise: a sample chamber in which a sample is accommodated; a
buffer chamber in which a buffer solution is accommodated; a
microfluidic chamber in which a microfluidic solution is
accommodated; a mixing chamber in which a solution for the
detection probe is accommodated, and which is connected to the
sample chamber, the buffer chamber, and the microfluidic chamber,
respectively, through channels, has an outlet disposed furthest
from the center of the disc-shaped platform, and performs reaction
of the sample and the microparticles, cleaning and separation of
the microparticles using the buffer solution according to control
of valves disposed at the respective channels and outlets; a waste
chamber which is connected to a portion adjacent to the outlet of
the mixing chamber and in which the fluid exhausted from the mixing
chamber is accommodated according to control of the valves disposed
at the paths; and an optical signal revelation chamber which is
connected to the outlets of the mixing chamber through the
channels, accommodates the separated microparticles, and provides
an optical signal generated by the detection probe.
[0018] The mixing chamber may be disposed further from the center
of the disc-shaped platform than the sample chamber, the buffer
chamber, and the microparticle chamber and is disposed closer to
the center of the disc-shaped platform than the waste chamber and
the optical signal revelation chamber. A channel for connecting the
mixing chamber and the waste chamber may be connected to a position
in which a space in which the microparticles are deposited is
formed between the connection portion of the mixing chamber and the
outlet of the mixing chamber.
[0019] The channel for connecting the mixing chamber and the waste
chamber may be opened and closed by the valves. The channel for
connecting the mixing chamber and the waste chamber may be
constituted so that opening and closing operations are repeatedly
performed using valves at least twice.
[0020] Channels for connecting the buffer chamber and the mixing
chamber may be connected to positions corresponding to several
levels of the buffer chamber, and valves that operate separately
are disposed at each of the channels. The microparticles may be
magnetic beads, and the immunoassay unit may be disposed adjacent
to the optical signal revelation chamber and include a material
used in forming a magnetic field for condensing magnetic beads
within the optical signal revelation chamber by a magnetic
force.
[0021] The immunoassay unit may further comprise a reagent which is
accommodated in the optical signal revelation chamber, is mixed
with the cleaned and separated microparticles, and reacts the
optical signal revelation material of the detection probe attached
to target protein to generate an optical signal. The microfluidic
structure of the immunoassay unit may further comprise a fixing
chamber which is disposed further from the center of the
disc-shaped platform than the optical signal revelation chamber and
is connected to an outlet of the optical signal revelation chamber,
wherein a fixing solution is disposed inside the fixing chamber to
stop a reaction of the optical signal revelation material and the
reagent.
[0022] The microfluidic structure of the immunoassay unit may
further comprise a centrifugal separation unit which is connected
to the sample chamber and the mixing chamber, centrifugally
separates the sample accommodated in the sample chamber, and
provides a supernatant of the sample to the mixing chamber.
[0023] According to another aspect of the present invention, there
is provided a microfluidic device for conducting multiple
biological assays simultaneously, the device comprising: a platform
which can be rotated; a first assay unit which is disposed at one
portion of the platform and detects a first target material from a
biological sample using a microarray chip having capture probes
arranged on its surface; and a second assay unit which is disposed
at another portion of the platform and detects a second target
material included in the sample by a reaction of the sample and a
previously-loaded reagent which selectively reacts with the second
target material, wherein the first assay unit comprises a
microfluidic structure which includes a plurality of chambers, a
plurality of channels for connecting the plurality of chambers, and
a plurality of valves for controlling the flow of a fluid through
the channels by rotation of the platform and the valves, and the
plurality of valves comprise at least one phase transition valve
comprising a valve material in which heat-generating particles are
dispersed in a phase transition material, in which that the phase
transition material is in a solid state at a room temperature and
in a liquefied state at a temperature higher than the melting point
of the phase transition material, and the valve material changing
into a molten state by heat generated due to energy applied to the
heat-generating particles, resulting in opening or closing its
corresponding channel path.
[0024] In an embodiment, there is provided a disc-shaped
microfluidic device for conducting immunoassay and biochemistry
analysis simultaneously, the device comprising: a disc-shaped
platform which can be rotated; an immunoassay unit which is
disposed at one portion of the disc-shaped platform and detects
various target proteins from a sample using a microarray chip
having capture probes arranged on its surface; and a biochemistry
analysis unit which is disposed at another portion of the
disc-shaped platform and detects a target material included in the
sample by a biochemical reaction of the sample and a
previously-stored reagent, wherein the immunoassay unit comprises a
microfluidic structure which includes a plurality of chambers, a
plurality of channels for connecting the plurality of chambers, and
a plurality of valves for controlling the flow of a fluid through
the channels and manipulates a fluidic sample by rotation of the
disc-shaped platform and the valves, and the plurality of valves
comprise at least one phase transition valve comprising a valve
material in which heat-generating particles are dispersed in a
phase transition material that is in a solid state at room
temperature and in a liquefied state at high temperatures, and the
valve material moving in a molten state by heat generated due to an
electromagnetic beam radiated from an external energy source, in
order to open or close its corresponding channel path.
[0025] The microarray chip may be mounted on the disc-shaped
platform so that capture probes bound on its surface are in contact
with the sample inside the microfluidic structure.
[0026] The microfluidic structure of the biochemical analysis unit
may comprise: a sample chamber in which a sample is accommodated; a
reaction chamber which is connected to the sample chamber and in
which a reagent for detecting a target material through a
biochemical reaction is accommodated; and a detection chamber in
which a reaction resultant of the sample and the reagent is
accommodated to be optically detected.
[0027] The microfluidic structure of the biochemical analysis unit
may further comprise a centrifugal separator which is connected to
the sample chamber and the reaction chamber, centrifugally
separates the sample accommodated in the sample chamber, and
provides a supernatant of the sample to the reaction chamber.
[0028] According to another aspect of the present invention, there
is provided a disc-shaped microfluidic device for conducting
immunoassay and biochemistry analysis simultaneously, the device
comprising: a disc-shaped platform which can be rotated; a
centrifugal separation unit which is disposed close to the center
of the disc-shaped platform, centrifugally separates the sample
using a centrifugal force generated by rotation of the disc-shaped
platform and exhausts a supernatant of the sample; a distribution
unit which distributes the supernatant of the sample exhausted from
the centrifugal separation unit into a plurality of metering
chambers in predetermined amounts; an immunoassay unit which is
disposed at one portion of the disc-shaped platform, includes a
plurality of chambers, a plurality of channels for connecting the
chambers, and a plurality of valves for controlling the flow of a
fluid through the channels, immunoassay unit detecting a target
material from the sample supplied by the distribution unit using a
capture probe-bound-surface; and a biochemistry analysis unit which
is disposed at another portion of the disc-shaped platform and
detects a target material included in the sample by a biochemical
reaction of the sample and a previously-accommodated reagent,
wherein the plurality of valves comprise a valve material in which
heat-generating particles are dispersed in a phase transition
material that is in a solid state at room temperatures and in a
liquefied state at high temperatures, and at least one phase
transition valve in which the valve material is moved in a molten
state by heat generated due to an electromagnetic beam radiated
from an external energy source, each phase transition valve opening
or closing its corresponding channel path.
[0029] The distribution unit may comprise: a distribution channel
which is connected to an outlet valve of the centrifugal separation
unit, extends along a circumferential direction of the disc-shaped
platform, and has a constant fluid resistance over all sections; a
plurality of metering chambers which are disposed further from the
center of the disc-shaped platform than the distribution channel in
a radius direction within the disc-shaped platform; and a plurality
of inlet channels which connect the distribution channel to the
plurality of metering chambers, wherein the distribution unit
distributes the supernatant of the sample exhausted from the
centrifugal separation unit to the plurality of metering chambers
through the distribution channel using centrifugal force generated
by rotation of the disc-shaped platform.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The file of this patent contains at least one drawing
executed in color. Copies of this patent with color drawing(s) will
be provided by the Patent and Trademark Office upon request and
payment of the necessary fee.
[0031] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0032] FIG. 1 is a schematic view of a disc-shaped microfluidic
device according to an embodiment of the present invention;
[0033] FIG. 2 is a plan view of a disc-shaped microfluidic device
having a plurality of immunoassay units and a plurality of
biochemical analysis units according to an embodiment of the
present invention;
[0034] FIG. 3 is a plan view of an immunoassay unit which can be
used in the disc-shaped microfluidic device according to an
embodiment of the present invention;
[0035] FIG. 4 is a plan view of an immunoassay unit which can be
used in the disc-shaped microfluidic device according to another
embodiment of the present invention;
[0036] FIG. 5 is a perspective view of a biochemical analysis unit
which can be used in the disc-shaped microfluidic device according
to another embodiment of the present invention;
[0037] FIG. 6 is a plan view of a disc-shaped microfluidic device
including a plurality of immunoassay units and a plurality of
biochemical analysis units according to another embodiment of the
present invention;
[0038] FIG. 7 is an enlarged plan view of the dotted region of FIG.
6 according to one embodiment of the present invention;
[0039] FIG. 8 is an enlarged plan view of the dotted region of FIG.
6 according to another embodiment of the present invention;
[0040] FIG. 9 is a plan view of an opening valve which can be used
in the immunoassay unit and the biochemical analysis unit of the
disc-shaped microfluidic device according to another embodiment of
the present invention;
[0041] FIG. 10 is a cross-sectional view of the opening valve taken
along line X-X' of FIG. 9;
[0042] FIG. 11 is a plan view of a closing valve which can be used
in the immunoassay unit and the biochemical analysis unit of the
microfluidic device according to an embodiment of the present
invention;
[0043] FIG. 12 is a cross-sectional view of the closing valve taken
along line XII-XII' of FIG. 11;
[0044] FIG. 13 is a series of high-speed photographs showing the
operation of the opening valve of FIG. 9;
[0045] FIG. 14 is a series of high-speed photographs showing the
operation of the closing valve of FIG. 11;
[0046] FIG. 15 is a graph showing the volume fraction of a
ferrofluid according to a valve reaction time in a valve material
used in the open valve of FIG. 9;
[0047] FIG. 16 is a graph showing power of a laser light source
that is used as an external energy source when the opening valve of
FIG. 9 is driven, and a valve reaction time, according to an
embodiment of the present invention; and
[0048] FIG. 17 is a flowchart illustrating a method of conducting
an immunoassay and a biochemical analysis using the disc-shaped
microfluidic device according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0049] The present invention will now be described more fully with
reference to the accompanying drawings, in which exemplary
embodiments of the invention are shown. Like reference numerals in
the drawings denote like elements, and thus their description will
not be repeated. The shapes of chambers and channels may be
simplified, and the ratio of their sizes may be increased or
reduced as compared to reality. In the expressions such as a
microarray chip, a microfluidic device, and a micro-particle,
`micro-` is just used having the opposite meaning to `macro-` and
should not be construed as being limiting the sizes of these
elements.
[0050] The term `microfluidic structure` employed in the present
specification does not indicate a particularly shaped structure but
indicates a microstructure comprising a plurality of chambers,
channels, and valves, which accommodates a fluid and controls of
the flow of the fluid. Thus, the `microfluidic structure` may
constitute units which perform different functions according to the
features of arrangement of chambers, channels, and valves and the
types of materials accommodated therein.
[0051] A `reagent` in the present specification is used to indicate
any kinds of agents, which can be used in the form of a solution
and which can produce an optically detectable reactant by a
reaction with a sample. In order to classify a reagent used for an
immunoassay and a reagent used for a biochemical analysis, the
reagent used for (or suitable for) the biochemical analysis is
referred to as a `biochemical reagent` for convenience.
[0052] The biological fluid or biological sample fluid which can be
tested according to the present invention include, but is not
limited to, blood, serum, plasma, urine, sweat, tear fluid, semen,
saliva, cerebral spinal fluid, or a purified or modified derivative
thereof. The sample may also be obtained from a plant, animal
tissue, cellular lysate, cell culture, microbial sample, or soil
sample, for example. The sample may be purified or pre-treated if
necessary before testing, to remove substances that might otherwise
interfere with the testing. Typically, the sample fluid will be an
aqueous solution of, for example, polypeptides, polynucleotides,
and salts. The solution may include surfactants or detergents to
improve solubility of the target substance (or analyte). For
non-polar and hydrophobic analytes, organic solvents may be more
suitable.
[0053] FIG. 1 is a schematic view of a disc-shaped microfluidic
device according to an embodiment of the present invention.
According to the present embodiment, the disc-shaped microfluidic
device 200 comprises at least one immunoassay unit IMU1 and IMU2
and at least one biochemical analysis unit BCU1 and BCU2 in a
disc-shaped platform 100 which can be rotated.
[0054] Here, the disc-shaped platform 100 is not limited to one
having a disc shape but includes one of a fan shape in which the
platform 100 is seated on a rotatable frame and can rotate. The
disc-shaped platform 100 may be formed of a plastic material of
which formation is easy and surface is biologically non-activated,
such as polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS)
or polycarbonate (PC). The material of the disc-shaped platform 100
is not limited to them and any material may be used as long as they
have chemical and biological stability, optical transparency, and
mechanical workability. The disc-shaped platform 100 can be
constructed with two or more disc-shaped plates. An engraved
structure corresponding to a chamber or a channel is formed on a
surface of one plate facing the other plate, and the plates are
bonded to provide a space and a path inside the resulting
disc-shaped platform 100. The plates of the disc-shaped platform
may be bonded using various known methods such as adhesion using an
adhesive, a double-sided adhesive tape or ultrasonic wave
fusion.
[0055] The immunoassay units IMU1 and IMU2 are units which
accommodate a biological fluid such as blood or serum separated
from blood, manipulate blood or serum within a microfluidic
structure (not shown) disposed at a portion of the disc-shaped
platform 100 and detect a target material such as an antibody,
antigen or protein from biological fluid. Here, each of the
immunoassay units IMU1 and IMU2 comprises a microfluidic structure
(not shown) comprising a plurality of chambers, a path connecting
the chambers and a valve controlling the flow of fluid. The valve
may contain at least one phase transition valve, as will be
described hereinafter (see FIGS. 9 through 14). The phase
transition valve contains a valve material in which heat-generating
particles are dispersed into a phase transition material that is in
a solid state at room temperatures and in a liquefied state at high
temperatures, wherein the valve material is moved in a molten state
by heat generated due to an electromagnetic beam radiated from an
external energy source in order to open or close the channel
path.
[0056] The biochemistry analysis units BCU1 and BCU2 are units
which accommodate a biological fluid sample such as blood, serum
separated from blood, urine or saliva and detect a target material
using a biochemical reaction and a reagent. The reagent may be
loaded in advance, for example, when the device is fabricated. The
reagent chemically reacts with the sample so that the target
material can be detected. In the embodiments of the present
application described herein, an optical detection is explained.
However, one skilled in the art should understand that the signal
by reaction of the target material-specific reagents with the
biological sample is measured by any suitable detection means,
including optical and non-optical methods.
[0057] Where the signal is detected optically, detection may be
accomplished using any optical detector that is compatible with the
spectroscopic properties of the signal. The assay may involve an
increase in an optical signal or a decrease. The optical signal may
be based on any of a variety of optical principals, including
fluorescence, chemiluminescence, light absorbance, circular
dichroism, optical rotation, Raman scattering, radioactivity, and
light scattering. In an embodiment, the optical signal is based on
fluorescence, chemiluminescence, or light absorbance.
[0058] In general, the optical signal to be detected will involve
absorbance or emission of light having a wavelength between about
180 nm (ultraviolet) and about 50 .mu.m (far infrared). More
typically, the wavelength is between about 200 nm (ultraviolet) and
about 800 nm (near infrared). A variety of detection apparatus for
measuring light having such wavelengths are well known in the art,
and include, but not limited to, the use of light filters,
photomultipliers, diode-based detectors, and/or charge-coupled
detectors (CCD).
[0059] FIG. 2 is a plan view of a disc-shaped microfluidic device
having a plurality of immunoassay units and a plurality of
biochemistry analysis units according to an embodiment of the
present invention. According to the present invention, the
disc-shaped microfluidic device 200 comprises a first immunoassay
unit (IMU1) 210 for detecting, for example, troponin I (TnI) which
is a cardiac marker, a second immunoassay unit (IMU2) 220 for
detecting plasma beta-chorionic gonadotropin (beta-hCG) indicating
pregnancy, a first biochemistry analysis unit (BCU1) 230 for
detecting ALT(Alanine Aminotransferase: GPT) and AST(Aspartate
Aminotransferase: GOT) which belong to a liver panel, and a second
biochemical analysis unit (BCU2) 240 for detecting amylase and
lipase indicating abnormality of a digestive system (in particular,
the pancreas).
[0060] The above examples are a selected combination of analytes to
be quickly tested for the medical treatment of a female emergency
patient. However, the present invention is not limited thereto and
test items may be added or substituted for other test items if
necessary. For example, when a test is conducted on an emergency
patient (man), the disc-shaped microfluidic device 200 may comprise
an immunoassay unit for detecting plasma B-type natriuretic peptide
(BNP) or N-terminal pro-BNP (NT-proBNP) which is a cardiac marker,
instead of the immunoassay unit for detecting beta-hCG among the
above examples. A doctor may verify regarding a disease in the
blood vessel system of a heart through TnI and BNP detection
results, verify regarding a liver disease and a liver function
through AST and ALT detection results and verify regarding
abnormality of the digestive system, in particular, pancreas
through amylase and lipase detection results.
[0061] In the diagnosis and the medical treatment of a body status
of an emergency patient, time required for the above tests is so
important in determining the success of the medical treatment. By
using the disc-shaped microfluidic device 200 according to the
present invention, information on the physical conditions of a
patient may be obtained from a small amount of samples within a
very short time.
[0062] The following Table 1 shows several examples of the
combinations of an immunoassay and biochemical analyses which can
be conducted simultaneously for a purpose of obtaining information
for diagnosing an emergency patient. In addition, various test
items may be combined depending on the condition or suspected
disease of the patient.
TABLE-US-00001 TABLE 1 Biochemistry Test Fields Immunoassays
analyses Remarks Emergency Cardiac marker Liver test (ALT,
Emergency (CK-MB*.sup.1, TnI, AST), Glucose, room myoglobin, pro-
Digestive BNP), .beta.-hCG test (amylase, lipase) Hepatitis and
HBsAg, Anti- Liver General (ALT: liver-function HBs, panel (AST,
chronic hepatitis examination Anti-HBc, Anti- ALT, TB, B patients'
HCV*.sup.2 Albumin, GGT) regular monitoring items) Blood sugar
HbA1C Glucose General test (HbA1C: provision of three-month average
blood sugar level) Heart's blood Cardiac marker Liver panel
Circulatory vessel (TC*.sup.3, HDL*.sup.4, organ internal system
diseases LDL*.sup.5, TG*.sup.6) medicine Thyroid test Free T4,
TSH*.sup.7 Glucose Endocrine internal medicine *.sup.1creatine
kinase-MB *.sup.2Hepatitis C virus *.sup.3total cholesterol
*.sup.4high density lipoprotein *.sup.5low density lipoprotein
*.sup.6triglycerides *.sup.7thyroid stimulating hormone
[0063] FIG. 3 is a plan view of an immunoassay unit which can be
used in the disc-shaped microfluidic device according to an
embodiment of the present invention. The upper portion of the
drawing corresponds to the center of the rotatable disc-shaped
platform 100 and the lower portion of the drawing corresponds to
the circumference of the disc-shaped platform 100. A microfluidic
structure of an immunoassay unit 210 according to the present
embodiment comprises a sample chamber 185 in which a fluidic sample
is accommodated, a buffer chamber 12 in which a buffer solution is
accommodated, and a microfluidic particle chamber 13 in which a
microfluidic particle solution containing a large amount of
microparticles M1 is accommodated. Each of the sample chamber 185,
the buffer chamber 12, and the microfluidic particle chamber 13 is
provided with an injection hole or inlet hole, and a user may load
the sample, the buffer solution, and the microparticle solution
through the injection hole.
[0064] A mixing chamber 14 is disposed further from the center of
the disc-shaped platform 100 than the three chambers 185, 12, and
13. The mixing chamber 14 is connected to the sample chamber 185,
the buffer chamber 12, and the microparticle chamber 13 through
channels 21, 22, and 23, respectively, which are fluid flow paths.
Valves 31, 32, and 33 for controlling the flow of the fluid are
disposed at the channels 21, 22, 23, respectively. The three valves
31, 32, and 33 may be opening valves which are closed at an initial
stage and are opened under predetermined conditions. The mixing
chamber 14 has an outlet that is disposed furthest from the center
of the disc-shaped platform 100, and a valve 34 (hereinafter,
referred to as an "outlet valve") is disposed at the outlet of the
mixing chamber 14. The cross-sectional width of the mixing chamber
14 may gradually decrease as it is towards radially outward of the
disc-shaped platform 100. That is, the cross-sectional width of the
mixing chamber 14 that is close to the outlet valve 34 may be
smaller. To this end, a portion of an inside of the outlet valve 34
may also be channel-shaped. A previously-loaded detection probe
solution (or detection agent solution) is accommodated in the
mixing chamber 14, the sample is supplied to the mixing chamber 14
from the sample chamber 185, the microparticle M1 solution is
supplied to the mixing chamber 14 from the microparticle chamber
13, and the buffer solution is supplied to the mixing chamber 14
from the buffer chamber 12.
[0065] A waste chamber 15 is disposed further from the center of
the disc-shaped platform 100 than the mixing chamber 14. The waste
chamber 15 may be connected to a portion that is close to the
outlet valve 34 of the mixing chamber 14 through a channel 25,
i.e., a portion in which the cross-sectional width of the mixing
chamber 14 is small, as described above. A space may be formed
between the portion of the mixing chamber 14 where the channel 25
is connected to and the outlet valve 34. The space may accommodate
microparticles which may be present in the mixing chamber 14 and
collected in the space.
[0066] The fluid may flow into the waste chamber 15 from the mixing
chamber 14 at least twice. First, a sample residue that has reacted
with the microparticles M1 flows in the waste chamber 15 and a
buffer solution that has rinsed the microparticles M1 flows in the
waste chamber 15. Thus, the channel 25 may comprise a valve which
repeatedly performs opening and closing operations at least twice.
When a one-time valve for performing only an opening or closing
operation once is used, the channel 25 may comprise at least two
divergence channels 25a and 25b through which the fluid passes
toward the waste chamber 15 from the mixing chamber 14 once each.
In addition, the two divergence channels 25a and 25b may be closed
after communicating with the fluid once each. To this end, the
divergence channels 25a and 25b may comprise opening valves 35a and
35b and closing valves 45a and 45b, respectively.
[0067] In addition, an optical signal revelation chamber 16 is
disposed further from the center of the disc-shaped platform 100
than the outlet of the mixing chamber 14. The optical signal
revelation chamber 16 is connected to an outlet valve 34 of the
mixing chamber 14 through a channel 26. The optical signal
revelation chamber 16 may accommodate a previously-loaded target
material-specific reagent so that the reagent can react with an
optical signal-producing material of the detection probe. The
detection probe is bound to the surface of the microparticles M1.
The microparticles M1 are also coupled to a target material. The
diction probe-microparticle-target material complex enters the
optical signal revelation chamber 16. Upon reaction with the
reagent and the optical signal-producing material of the detection
probe, an optical signal is generated. A substrate or enzyme that
is needed to react with the optical signal revelation material of
the detection probe and to generate an optical signal may be
included in the reagent.
[0068] When the microparticles M1 are magnetic beads, a magnetic
material generating a magnetic field, for example, a magnet 231,
may be disposed in a portion that is adjacent to the optical signal
revelation chamber 16. The magnet 231 may condense the magnetic
beads used as the microparticles M1 described above. The magnet 231
may control the position of the magnetic beads by moving to various
positions above or below the disc-shaped platform 100. For example,
the magnet 231 may play a role for moving the magnet beads that are
separated by centrifugal force in the vicinity of the outlet of the
mixing chamber 14 to the center of the mixing chamber 14 to be
easily dispersed into the solution in the mixing chamber 14.
[0069] The buffer chamber 12 may have a large capacity to store a
buffer solution in which the microparticles M1 can be rinsed
several times (for example, three times), the channel 22 for
connecting the buffer chamber 12 and the mixing chamber 14 may
diverge into several parts, and the diverged channel parts may be
connected to positions corresponding to several levels of the
buffer chamber 12. At this time, valves 32a, 32b, and 32c may be
provided to the diverged channel parts and may be opening valves
that operate separately.
[0070] In addition, channels 25c and 25d and valve structures 35c
and 35d may be disposed. These channels and valve structures
exhaust the fluid to the waste chamber 15 from the mixing chamber
14 depending on the levels of the buffer chamber 12, followed by
the closing of the paths. This is because the buffer solution
accommodated in the buffer chamber 12 is supplied to the mixing
chamber 14 in a predetermined amount so that the microparticles M1
are cleaned and the used buffer separated from the microparticles
M1 is exhausted to the waste chamber 15.
[0071] The immunoassay units 210 according to the present
embodiment may include a centrifugal separation unit 180 including
the sample chamber 185. The centrifugal separation unit 180
comprises a supernatant separator 182 that extends from the outlet
of the sample chamber 185 toward radially outward of the platform
100 and a particle separator 181 that is connected to the
supernatant separator 182 through a channel. One side of the
supernatant separator 182 is connected to the mixing chamber 14
through an opening valve 31 and a channel 21. At this time, the
particle separator 181 and the supernatant separator 182 may be
connected through a bypass channel 183. The bypass channel 183 acts
a vent of the particle separator 181. A surplus sample chamber 184
is connected to a portion of the bypass channel 183, and when a
surplus amount of sample is loaded into the sample chamber 185, a
predetermined amount of a supernatant (e.g., serum) may be supplied
to the mixing chamber 14.
[0072] Exemplifying the operation of the centrifugal separation
unit 180, when whole blood is loaded into the sample chamber 185
and the disc-shaped platform 100 is rotated, heavy blood corpuscles
are collected in the particle separator 181 and the supernatant
separator 182 is filled with serum. At this time, if the valve 31
of the channel 21 connected to the mixing chamber 14 is opened,
serum filled in a portion that is positioned radially inward than
the portion of the supernatant separator 182 connected to the
channel 21 is conveyed to the mixing chamber 14.
[0073] The microfluidic structure of the immunoassay unit 210
according to the present embodiment may further include a fixing
member 17 which is connected to the optical signal revelation
chamber 16 via a valve 37 disposed therebetween. The fixing chamber
17 may contain a fixing (or quenching) solution for stopping a
reaction of a reagent disposed in the optical signal revelation
chamber 16 and the optical signal revelation material of the
detection probe. By the action of the fixing solution, a reaction
for providing an optical signal revelation is stopped and the
intensity of the optical signal can be maintained based on a time
when the valve 37 is opened and a mixed solution of microparticles
including a surface absorption material and the reagent flows. By
using this advantage, the proceeding time of the optical signal
revelation reaction can be limited. Thus, when the optical signal
is detected using an optical detector (not shown), which may be
disposed outside the disc-shaped platform 100, an accurate result
can be obtained without being affected by its measuring time.
[0074] The microparticles M1 have a capture probe which
specifically binds to a target material (antigen, antibody or
marker protein etc.). The capture probe is coupled to or attached
to the surface of the microparticles. The binding between the
capture probe and the target material allows to separate the target
material from a biological sample. For example, since the capture
probe has a specific affinity only to a particular target material,
it is useful for detecting a very small amount of the target
material included in the sample. The microparticles M1 of which
surface is modified with a probe and can be used to separate target
materials of interest (e.g., antigen) are commercially available
from various sources such as Invitrogen or Qiagen, and examples
thereof are DYNABEADS.TM. Genomic DNA Blood (Invitrogen),
NYNABEADS.TM. anti-E.coli O157(Invitrogen), CELLection.TM. Biotin
Binder Kit (Invitrogen), and MagAttract Virus Min M48 Kit.TM.
(Qiagen). Diphtheria toxin, Enterococcus faecium, Helicobacter
pylori, HBV, HCV, HIV, Influenza A, Influenza B, Listeria,
Mycoplasma pneumoniae, Pseudomonas sp., Rubella virus, and
Rotavirus may be detected using microparticles to which the
particular antibody is attached. A marker protein indicating a
heart disease or pregnancy may be detected according to the types
of capture probes fixed on the surface of the microparticles, as
described above.
[0075] The sizes of the microparticles M1 may be 50 nm-1,000 .mu.m.
In one embodiment, the microparticles have a size of 1 .mu.m-50
.mu.m. In addition, the microparticles M1 may be formed by mixing
microparticles of two or more sizes.
[0076] The microparticles M1 may be formed of various materials. In
particular, the microparticles M1 may be magnetic beads including
at least one of ferromagnetic metals such as Fe, Ni, and Cr and an
oxide thereof.
[0077] Materials for a detection probe used in a conventional
enzyme-linked immunoserological assay (ELISA) process may be used
in the protection probe including the optical signal revelation
material. For example, when a primary antibody is attached on the
surface of the microparticles M1 as a capture probe so as to detect
a particular antigen, a secondary antibody to which horseradish
peroxidase (HRP) is linked may be used as a detection probe. At
this time, a reagent including a substrate and an enzyme of which
colors are revealed by a reaction with HRP may be disposed in the
optical signal revelation chamber 16.
[0078] FIG. 4 is a plan view of an immunoassay unit which can be
used in the disc-shaped microfluidic device according to another
embodiment of the present invention. According to the present
embodiment, a microfluidic structure including a plurality of
chambers 120, 130, 140, and 150, a plurality of paths for
connecting the chambers 120, 130, 140, and 150, and a plurality of
valves 310, 320, 330, and 340 for controlling the flow of a fluid
through each of the paths is disposed within the disc-shaped
platform 100. Here, the paths may be channel-shaped.
[0079] A microarray chip 190 is mounted on the disc-shaped platform
100 so that a plurality of capture probes 191n bound in an array
form on the surface of the microarray chip 190 is in contact with a
sample (serum) passing a portion of the microfluidic structure.
[0080] In the present embodiment, the construction of the
microfluidic structure disposed in the disc-shaped platform 100
will now be described. First, the microfluidic structure may
include a sample chamber 185 in which a sample such as blood is
accommodated, and a centrifugal separation unit 180 which is
connected to the sample chamber 185 and separates a supernatant
from the sample. In addition, the microfluidic structure may
include a reagent chamber 130 for storing a reagent and a buffer
solution chamber 120 for storing a buffer solution. The reagent
including a material that is selectively bounds to a target
material of the sample and provides an optical signal such
fluorescence, absorption, and emission may be previously loaded and
stored in the reagent chamber 130, and a buffer solution needed to
dilute the sample or to clean the surface of the microarray chip
190 contacting the sample may be previously loaded and stored in
the buffer solution chamber 120.
[0081] The centrifugal separation unit 180, the reagent chamber
130, and the buffer solution chamber 120 are connected to the
reaction chamber 140, which is disposed radially outward than the
outlets of the centrifugal separation unit 180 and the chambers 120
and 130, via opening valves 310, 320, and 330. The valves 310, 320
and 330 are disposed at the outlet of the unit 180, chamber 120 and
chamber 130, respectively. The opening valves 310, 320, and 330 are
phase transition valves (see FIGS. 9 and 10) which are disposed so
that a valve plug formed of a valve material in which a plurality
of heat-generating particles are dispersed in a phase transition
material in a solid state at room temperature, closes a flow path
at an initial stage, and the valve plug is actively opened by the
supply of a driving energy from an external energy source. One wall
surface of the reaction chamber 140 may be formed of the microarray
chip 190 and the fluidic sample may contact the capture probes 191n
in front of the microarray chip 190. At this time, the microarray
chip 190 may be mounted in various shapes on the disc-shaped
platform 100.
[0082] A waste chamber 150 is disposed radially outward of the
reaction chamber 140. The fluid existing from the reaction chamber
140 is accommodated in the waste chamber 150. An opening valve 340
is disposed at the outlet of the reaction chamber 140 and may
confine the fluid within the reaction chamber 140 while a reaction
with the sample is performed.
[0083] The centrifugal separation unit 180 includes a supernatant
separator 182 that extends from the outlet of the sample chamber
185 towards radially outward and a particle separator 181 that is
connected to the supernatant separator 182 through a channel. One
side of the supernatant separator 182 is connected to the reaction
chamber 140 through the opening valve 310 and the channel. At this
time, the particle separator 181 and the supernatant separator 182
may be connected around through a bypass channel 183. The bypass
channel 183 acts as a vent of the particle separator 181. A surplus
sample chamber 184 is connected to a portion of the bypass channel
183, and when a surplus amount of a sample is loaded into the
sample chamber 185, a predetermined amount of a supernatant may be
supplied to the reaction chamber 140.
[0084] A channel for connecting the buffer solution chamber 120 and
the reaction chamber 140 is divided into several parts, and the
channel parts may be connected to positions corresponding to
several levels of the buffer solution chamber 120. At this time,
valves 320a, 320b, and 320c may be provided to channel parts and
may be opening valves that operate separately. This is because the
buffer solution accommodated in the buffer solution chamber 120 is
supplied to the reaction chamber 140 by a predetermined amount so
that the surface of the microarray chip 190 on which the reaction
is completed can be cleaned several times.
[0085] Here, the microarray chip 190 may be a microarray chip in
which various capture probes 191n that capture a target material
are bound in an array form on a chip-shaped substrate. For example,
the chip-shaped substrate may be formed of glass, silicon or
plastics, and the capture probes 191n may be protein, cells or
other biochemical materials.
[0086] An operation of detecting a target material in the
immunoassay unit according to the present embodiment will now be
described. The following description is directed to an example in
which a protein microarray chip is used as the microarray chip 190.
The features of the immunoassay unit that can be used in the
disc-shaped microfluidic device according to the present invention
may be further described. Here, the protein microarray chip is an
example of the microarray chip 190 and thus the same reference
numeral is used. If whole blood is loaded into the sample chamber
185 and the disc-shaped platform 100 is rotated, heavy blood
corpuscles are collected in the particle separator 181 and the
supernatant separator 182 is filled with serum. At this time, if
the opening valve 310 of the channel connected to the reaction
chamber 140 is opened, serum filled in a portion that is closer to
the center of rotation (i.e., positioned radially inward) than the
portion of the supernatant separator 182 connected to the channel
is conveyed to the reaction chamber 140.
[0087] The previously-loaded reagent is conveyed to the reaction
chamber 140 by opening the opening valve 330 disposed at the outlet
of the reagent chamber 130. The reagent may include materials for a
detection probe used in a conventional enzyme-linked
immunoserological assay (ELISA) process, for example, as an optical
signal revelation material. When a primary antibody is bound to the
surface of the microarray chip 190 as a capture probe for detecting
particular target protein, the reagent may comprise a secondary
antibody to which horseradish peroxidase (HRP) as the optical
signal revelation material is coupled. At this time, the reagent
may include a substrate and an enzyme of which colors are revealed
by a reaction with HRP.
[0088] A mixed solution of the reagent and serum is in contact with
the protein microarray chip 190 in the reaction chamber 140 and is
incubated for several minutes to several tens of minutes. As a
result, a target protein is captured in the capture probes 191n in
which the corresponding target protein exists in the sample, and
the secondary antibody (to which the optical signal revelation
material is coupled) included in the reagent is attached to the
target protein regardless of a temporal order.
[0089] After a certain period of time which is sufficient for the
completion of the reaction, the opening valve 340 disposed at the
outlet of the reaction chamber 140 is opened, and the fluid within
the reaction chamber 150 exists into the waste chamber 150 by the
action of a centrifugal force. Then, a buffer solution of a
predetermined amount is conveyed to the reaction chamber 140 by the
action of a centrifugal force whenever the opening valves 320a,
320b, and 320c located to corresponding to several levels of the
buffer solution in the buffer solution chamber 120 are sequentially
opened, thereby cleaning the surface of the microarray chip 190.
The buffer solution which is used to clean the surface of the
microarray chip 190 leaves the reaction chamber 140 and enters into
the waste chamber 150. The microarray may be fabricated by methods
well known in the art.
[0090] The microparticles M1 and the microarray chip 190, as
discussed above, are explained solely as an example of a medium
which carries a capture probe, and the present invention is not
limited thereto. Instead of the microparticles M1 and the
microarray chip 190, the capture probe may be bound to an inner
surface of at least one of the plurality of chambers in the
microfluidic structure is used. For example, an inner surface of
the mixing chamber 14 in FIG. 3 and an inner surface of the
reaction chamber 140 in FIG. 4 can be adopted as the capture
probe-bound-surface.
[0091] FIG. 5 is a perspective view of a biochemical analysis unit
which can be used in the disc-shaped microfluidic device according
to another embodiment of the present invention. The biochemical
analysis unit 230 is constructed in such a way that a biological
sample such as serum, urine or salvia reacts with a predetermined
biochemical reagent, generating a product of which an optical
property such as absorption or fluorescence varies depending on the
amount of a target material included in the biological sample. In
order to perform an operation of separating serum from blood and
the above-described operations, the biochemical analysis unit 230
contains a sample storing portion 530 in which blood is
accommodated, a particle separator 542 in which blood corpuscles
separated from blood by centrifugal separation are collected, a
supernatant separator 540 in which serum separated from blood by
centrifugal separation are collected, two outlet valves 531 and 532
which are disposed to distribute a predetermined amount of serum
within the supernatant separator 540 into two reaction chambers 55
and 56, respectively, and detection chambers 51 and 52 in which
resultant materials generated by a reaction between a
previously-loaded biochemical reagent and serum are accommodated
respectively. The above-described biochemical analysis unit 230 is
just an example of a biochemical analysis unit which can be used in
the disc-shaped microfluidic device 200 according an embodiment of
the present invention.
[0092] FIG. 6 is a plan view of a disc-shaped microfluidic device
including a plurality of immunoassay units and a plurality of
biochemical analysis units according to another embodiment of the
present invention. The microfluidic device 201 includes a sample
chamber 185, a centrifugal separation unit 180 which centrifugally
separates a sample accommodated in the sample chamber 185 and
exhausts a supernatant of the sample, and a distribution unit which
distributes the supernatant of the sample exiting from the
centrifugal separation unit 180 into a plurality of metering
chambers 501 through 506 by a predetermined amount.
[0093] A distribution channel 400 is connected to an outlet valve
311 of the centrifugal separation unit 180. The distribution
channel 400 extends from the outlet valve 311 along a
circumferential direction of the platform 100. A vent having a vent
hole may be connected to the end of the distribution channel 400.
The vent hole may be disposed in a position in which the sample
does not leak when it is conveyed. The fluid resistance of the
distribution channel 400 is constant over all sections from the
front end connected to the outlet valve 311 to the rear end
connected to the vent. In order to make the fluid resistance
constant, the cross-section of the distribution channel 400 may be
made constant over all sections. As such, resistance against the
movement of a fluid that is subject to be additionally applied when
the sample is distributed is minimized so that the sample can be
fast and efficiently distributed.
[0094] The plurality of sealed metering chambers 501 through to 506
are disposed outside the distribution channel 400 within the
platform 100. `Sealed` means a form in which a vent for exhausting
is not disposed in each of the metering chambers 501 through 506.
One of the metering chambers 501 through 506 may be disposed in
each of the immunoassay units 211 and 221 or the biochemical
analysis units 231, 232, 241, and 242. Such a construction enables
a biological sample be separated into a supernatant and a
precipitate and the supernatant be provided to the plurality of
immunoassay units 211 and 221 and the plurality of biochemical
analysis units 231, 232, 241, and 242 in a predetermined amount,
without manual individual distribution or loading of the sample
into each unit in comparison to the embodiments of FIGS. 2 through
5.
[0095] The plurality of sealed metering chambers 501 through to 506
are connected to the distribution channel 400 through inlet
channels 421 through to 426, respectively. The inlet channels 421
through to 426 and the distribution channel 400 may be connected to
one another to be T-shaped, as illustrated in a dotted region of
FIG. 6. At this time, the inlet channels 421 through to 426 may be
disposed in a radius direction of rotation of the disc-shaped
platform 100.
[0096] FIG. 7 is an enlarged plan view of the dotted region of FIG.
6. An inlet channel 421 having a single channel shape is shown in
FIG. 7 as an example of the above-described inlet channels 421
through 426. Most fluid sample supplied to the distribution channel
400 by centrifugal force proceeds toward the metering chamber 501
along the inlet channel 421 in a portion in which the distribution
channel 400 and the inlet channel 421 are connected. This is
because the direction of the centrifugal force acting on the sample
is identical to the direction in which the inlet channel 421 is
disposed. The cross-sectional width of the inlet channel 421 may be
larger than or the same as the cross-sectional width of the
distribution channel 400. This is because, when the fluid sample F
supplied through the distribution channel 400 flows into the
metering chamber 501, the fluid sample F is not completely filled
in the inlet channel 421 but the air in the metering chamber 501 is
exhausted through the remaining space. When the depth of the
distribution channel 400 and the depth of the inlet channel 421 are
the same, the relationship between the width dd of the distribution
channel 400 and the width di of the inlet channel 421 may satisfy
di.gtoreq.dd. However, it is not necessary to satisfy this
relationship. This is because, even when the inlet channel 421 is
clogged by the fluid sample F in the state where a space remains in
the metering chamber 501, if the cross-sectional width of the inlet
channel 421 is sufficiently large, the centrifugal force acting on
the fluid sample F within the inlet channel 421 is larger than the
surface tension of the fluid sample F so that the surface of the
fluid sample F collapses, the sample is moved into the metering
chamber 501 in the form of droplets and the bubbles of a volume
corresponding to the droplet-shaped sample are moved to the
distribution channel 400.
[0097] When one metering chamber 501 is completely filled through
the above-described operation, the fluid sample F does not flow in
the corresponding metering chamber 501 any more, is further moved
along the distribution channel 400 and is filled in the next
metering chamber 502. However, even when one metering chamber 501
is not completely filled, part of the fluid sample F may proceed
toward the next metering chamber 502.
[0098] FIG. 8 is an enlarged plan view of the dotted region of FIG.
6 according to another embodiment. An inlet channel 421A having a
multiple channel shape is shown in FIG. 8 as another example of the
above-described inlet channels 421 through to 426. The multiple
channel-shaped inlet channel 421A comprises barrier ribs 433 that
are disposed in along the lengthwise direction of the middle of the
channel. The barrier ribs 433 may be installed so that the flow
path in the direction of the distribution channel 400 is
intercepted on its inner end 433A. The inlet channel 421A is
divided by the barrier ribs 433 into two subchannels 431 and 432.
The barrier ribs 433 guide the sample flowing along the
distribution channel 400 to first flow to the metering chamber 401
through the subchannel 431 in front of the barrier ribs 433 (based
on the flow direction of the fluid sample F). At this time, the air
corresponding to the volume of the sample flowing to the metering
chamber 501 is exhausted into the distribution channel 400 through
the other subchannel 432. When one metering chamber 501 becomes
completely filled, the fluid sample F does not flow in the inlet
channel 421A but flows along the distribution channel 400 through
the inner end 433A of the barrier ribs 433 and inner walls 400W of
the distribution channel 400.
[0099] The barrier ribs 433 may be installed so that a resistance
applied to the fluid sample F when the fluid sample F proceeds
toward the subchannel 431 is smaller than or the same as a
resistance applied to the fluid sample F when a portion of the
distribution channel 400 is clogged by the inner end 433A of the
barrier wall and the fluid sample F proceeds along the distribution
channel 400. As an example, the cross-sectional width between the
inner end 433A of the barrier ribs 433 and the inner walls 400W of
the distribution channel 400 may be smaller than or the same as the
cross-sectional width of the subchannel 431. In particular, when
the depth of the distribution channel 400 and the depth of the
inlet channel 421A are the same, the relationship between dc and dp
shown in FIG. 6 may satisfy dc.ltoreq.dp.
[0100] FIG. 9 is a plan view of an opening valve which can be used
in the immunoassay unit and the biochemical analysis unit of the
disc-shaped microfluidic device according to another embodiment of
the present invention, and FIG. 10 is a cross-sectional view of the
opening valve taken along line X-X' of FIG. 9. An opening valve 30
comprises a valve plug 83 which is formed of a valve material in a
solid state at room temperature. A material in which heat
generating particles are dispersed in a phase transition material
in a solid state at room temperature can be used as the valve
material. A pair of drain chambers 82 having an enlarged width and
depth are disposed, to provide space, at the upstream and
downstream of a channel 43 adjacent to an initial position in which
the solid-state valve plug 83 is disposed.
[0101] The valve plug 83 closes a predetermined portion of the
channel 43 at room temperature, thereby intercepting the flow of a
fluid F that in-flowed from an inlet I. The valve plug 83 is molten
at a temperature higher than the melting point of the phase change
material contained in the valve, moves to the drain chambers 82
that are respectively adjacent to the upstream and downstream of
the channel 43 and is again solidified while opening the flow path
of the fluid F. An opening 83A functions as an injection (inlet)
hole through which a melted valve material is loaded to form the
valve plug 83 when a centrifugal force-based microfluidic device is
manufactured.
[0102] In order to heat the valve plug 83, an external energy
source (not shown) is disposed outside the disc-shaped platform
100, and the external energy source radiates an electromagnetic
beam (see dotted arrows of FIG. 10) on the initial position of the
valve plug 83, that is, on the opening 83A and a region including
the circumference of the valve plug 83. In this case, the external
energy source is a laser light source radiating a laser beam, and
in this case, the external energy source may include at least one
laser diode. The laser light source may radiate a pulse laser
having an energy of 1 mJ/pulse or higher, and may radiate a
continuous wave laser having an output of 10 mW or higher.
[0103] A laser light source, radiating laser light having a
wavelength of 808 nm, is used in experiments described with
reference to FIGS. 13 through 16. However, the present invention is
not limited to the radiation of laser light having the wavelength
of 808 nm, and a laser light source radiating laser light having a
wavelength of 400-1300 nm can be used as the external energy source
of the microfluidic device.
[0104] The channel 43 may be provided by cubic patterns that are
formed inside the upper plate 101 or the lower plate 102 of the
disc-shaped platform 100. The upper plate 101 is formed of an
optically transparent material through which an electromagnetic
beam radiated by the external energy source is transmitted incident
on the valve plug 83, and thus, the flow of the fluid F can be
observed from the outside due to the transparency. As an example
thereof, glass or transparent plastic materials may be advantageous
in view of excellent optical transparency and low manufacturing
cost.
[0105] The heat generating particles dispersed in the valve plug 83
have a diameter of 1 nm to 100 .mu.m so as to freely flow within
the channel 43 having a width of about several thousands of
micrometers (.mu.m). The heat generating particles have the
characteristic by which, when a laser is radiated on the particles,
the temperature of the heat generating particles rapidly rises due
to the radiation energy of the laser, and the heat generating
particles dissipate heat and are uniformly dispersed in a wax.
Also, the heat generating particles may have a structure comprising
a core including a metal component and a shell that has a
hydrophobic property so as to have the above-described
characteristic. For example, the heat generating particles may have
a structure comprising a core formed of a ferromagnetic material,
such as Fe, and a shell including a plurality of surfactants that
are combined with Fe and which encompass Fe. Such a material is
usually called a magnetic fluid. Generally, the heat generating
particles are kept in a state where the heat generating particles
are dispersed in a carrier oil that may also have a hydrophobic
property so that the heat generating particles that have a
hydrophobic surface structure can be uniformly dispersed. The
carrier oil in which the heat generating particles are dispersed is
mixed with the wax so that the material of the valve plug 83 can be
manufactured. The shape of the heat generating particles is not
limited to the shape of as describe above and the heat generating
particles can also be polymer beads, quantum dots, Au
nanoparticles, Ag nanoparticles, beads with metal composition,
carbon particles or magnetic beads. The carbon particles include
graphite particles.
[0106] A phase transition material used in forming the valve plug
83 may be a wax.
[0107] When the energy of the electromagnetic beam is transmitted
to the platform, for example to the circumference area, in the form
of a heat energy, the wax is melted due to the heat generating
particles which absorb the heat energy and has fluidity and as
such, the valve plug 83 collapses and the flow path of the fluid F
is opened. The wax of the valve plug 83 may have a melting point
which is chosen or adjusted to be not too high or not too low. This
is because, if the melting point is too high, the wax requires a
large amount of time to be melted and it is difficult to precisely
control an opening time of the flow path of the fluid F and if the
melting point is too low, the wax may partially melt even in the
absence of the application of external energy and the fluid F may
leak. Also, the wax can be paraffin wax, microcrystalline wax,
synthetic wax, natural wax, etc. The phase transition material can
also be gel or thermoplastic resin. The gel can be polyacrylamide,
polyacrylates, polymethacrylates or polyvinylamides etc. In
addition, the thermoplastic resin can be cyclic olefin copolymer
(COC), poly(methyl methacrylate) (PMMA), polycarbonate (PC),
polystyrene (PS), polyoxymethylene (POM), perfluoroalkoxy (PFA),
polyvinylchloride (PVC), polypropylene (PP), polyethylene
terephthalate (PET), polyetheretherketone (PEEK), polyacrylate
(PA), polysulfone (PSU) or polyvinyldiene fluoride (PVDF).
[0108] FIG. 11 is a plan view of a closing valve which can be used
in the immunoassay unit and the biochemical analysis unit of the
microfluidic device according to an embodiment of the present
invention, and FIG. 12 is a cross-sectional view of the closing
valve taken along line XII-XII' of FIG. 11. A closing valve 40
includes a channel 43 having an inlet I and an outlet O, a valve
material container 85 connected to the middle of the channel 43,
and a valve material V which is inserted in the valve material
container 85 in a solid state at room temperature at an initial
stage. If the valve material V is heated, the valve material V is
melted and expands, enters the channel 43, solidifies again and
intercepts the channel 43 through a valve connection path 86.
[0109] Like the above-described opening valve 30 of FIG. 9, the
closing valve 40 of the present embodiment may also be provided
with cubic patterns that are formed inside the upper plate 101 or
the lower plate 102 of the disc-shaped platform 100 of the
microfluidic device. The upper plate 101 may be formed of an
optically transparent material in which an electromagnetic beam
radiated by an external energy source (not shown) is transmitted,
and thus, a fluid sample F can be observed from the outside due to
the transparency. Furthermore, the upper plate 101 may have an
opening 85A corresponding to the valve material container 85 so as
to function as an injection hole through which the valve material V
that melted when the microfluidic device is manufactured is
loaded.
[0110] The phase transition material P and the heat generating
particles M of the valve material V may be the same to those
described above with respect to the phase transition opening valve.
In addition, the external energy source which provides an
electromagnetic beam to the valve material V, may also be the same
to those described previously with respect to the phase transition
opening valve.
[0111] If laser beams are radiated on the valve material V
including the phase transition material P and the heat generating
particles M, the heat generating particles M absorb energy to heat
the phase transition material P. As such, the valve material V is
melted, expands, and enters the channel 43 through the valve
connection path 86. The valve material V that is solidified again
while contacting the fluid F within the fluid collecting channel
150 to form a valve plug so that the flow of the fluid sample F
through the channel 43 is controlled.
[0112] The result of an experiment in which a reaction time of the
above-described valve unit is measured is as follows. The pressure
of a working fluid in a test chip for the experiment was kept at 46
kPa. A syringe pump (Havard PHD2000, USA) and a pressure sensor
(MPX 5500DP.TM., Freescale semiconductor Inc., AZ, USA) were used
to keep the pressure constant at 46 kPa. A laser light source
having an emission wavelength of 808 nm and an output of 1.5 W was
used as an external energy source for radiating an electromagnetic
beam to the valve unit. Data on the reaction time of the valve unit
was obtained through a result analysis of a high-speed
photographing device (Fastcam-1024, Photron, Calif., USA). As a
wax, a ferrofluid which is a mixture of a dispersion of magnetic
beads of an average diameter of 10 nm as heat generating particles,
dispersed in a carrier oil, and a paraffin wax at the ratio of 1:1
is used. That is, a so-called ferrowax that has a volume fraction
of a ferrofluid of 50%, was used as the valve material.
[0113] FIG. 13 is a series of high-speed photographs showing the
operation of the opening valve of FIG. 9. A reaction time, which is
the time from when a laser beam starts to be radiated on the valve
plug 83 of the opening valve until when the valve plug 83 is melted
and the channel 43 is opened, was 0.012 seconds.
[0114] FIG. 14 is a series of high-speed photographs showing the
operation of the closing valve of FIG. 11. A reaction time, which
is the time from when a laser beam starts to be radiated on the
valve material of the closing valve until when the valve material
is melted and expands and the channel 43 is closed, was 0.444
seconds. Compared to the reaction time of a conventional wax valve
of 2-10 seconds, one of ordinary skill in the art can understand
that the reaction time is significantly shortened.
[0115] FIG. 15 is a graph showing the volume fraction of a
ferrofluid according to a valve reaction time in the valve material
used in the open valve of FIG. 9. When the volume fraction of the
ferrofluid increases, a reaction time is reduced. However,
regardless of this, when the volume fraction of the ferrofluid
increases to 70% or higher, the maximum hold-up pressure of the
valve plug tends to be reduced. Thus, the volume fraction of the
ferrofluid that is to be included in the valve plug in the valve
unit is determined by compromising a demand for a reaction time and
a demand for maximum hold-up pressure.
[0116] FIG. 16 is a graph showing power of a laser light source
that is used as an external energy source when the opening valve of
FIG. 9 is driven, and a valve reaction time, according to an
embodiment of the present invention. As an output of the laser
light source increases, a reaction time tends to be reduced.
However, if the output of the laser light source is close to 1.5 W,
a change in reaction time is subtle, and (although not shown in the
graph), if the output of the laser light source exceeds 1.5 W, the
reaction time quickly converges towards a predetermined minimum
reaction time because thermal conductivity is limited by paraffin
wax. In the experiment, for this reason, a laser light source
having an output of 1.5 W was used. However, the external energy
source of the present invention is not limited to this.
[0117] FIG. 17 is a flowchart illustrating a method of conducting
an immunoassay and a biochemical analysis using the disc-shaped
microfluidic device according to the present invention. The
features of the present invention will become more apparent by
describing an example of a method of simultaneously driving an
immunoassay (IM) unit and a biochemical analysis (BC) unit disposed
on one disc-shaped platform.
[0118] First, serum is separated from the loaded blood. This
operation is common in the IM unit and BC unit and thus may be
performed simultaneously in the two units so as to reduce the
overall test time. Like in the microfluidic device of FIG. 2, when
a centrifugal separation unit is disposed in each test unit, an
operation of manual loading of a blood sample into the sample
chamber of each unit and of simultaneously separating serum from
the blood sample may be performed. In addition, like in the
microfluidic device of FIG. 6, when there is a common centrifugal
separation unit for supplying separated serum to a plurality of
test units, a blood sample may be manually loaded only into the
common centrifugal separation unit and a serum separation operation
may be performed.
[0119] Next, separated serum is conveyed to a mixing chamber of
each unit. In the microfluidic device of FIG. 2, a plurality of
opening valves disposed in a channel connected to the mixing
chamber from each centrifugal separation unit are respectively
opened, and in the microfluidic device of FIG. 6, serum is
distributed into a plurality of metering chambers from the common
centrifugal separation unit and then, opening valves disposed at
the outlet of each metering chamber are respectively opened.
Conveying of serum is performed by a centrifugal force generated by
rotation of a disc-shaped platform after a corresponding valve is
opened.
[0120] Incubation is performed in the mixing chamber of the IM
unit. Although there will be differences depending on the materials
to be detected or types of detection probes, it may generally take
about 10 minutes to perform the incubation of a particular
combination of the material to be detected, a capture probe, and a
detection probe. While incubation is performed, a valve disposed at
the outlet of the mixing chamber of the IM unit is maintained in a
closed state.
[0121] While incubation is performed in the IM unit, a biochemical
analysis may be conducted by the BC unit. The numbers and interval
of detecting signals generated in the BC unit is generally
determined depending on the biochemical reaction of the target
material to be determined. Thus, in case of ALT and AST tests, the
detection data is obtained several times at predetermined time
intervals (e.g. 1 min.). On the other hand, in the case of amylase
and lipase tests, obtaining of detection data once after a
predetermined period of time has elapsed is sufficient. All of the
operations may be performed while the incubation step is performed
in the IM unit.
[0122] When the incubation is finished in the IM unit,
microparticles or a microarray chip having a capture probe may be
cleaned and a target material (to which the detection probe is
attached) attached to the surface of the capture probe may be
optically detected. A specific cleaning procedure has been
previously introduced in the description of embodiments of an
immunoassay unit.
[0123] It should be noted that even though various embodiments of
the present invention have been described with respect to the
detection and assay of different target materials in the respective
assay units, the present invention encompasses embodiments where
the same target material may be simultaneously detected and/or
analyzed in different assay units using different reagents.
[0124] According to an embodiment of the present invention, a
rotatable microfluidic device in which an immunoassay and a
biochemical analysis for various processes can be simultaneously
conducted and a microfluidic system including the disc-shaped
microfluidic device are provided so that time and effort for
performing of pathological tests can be remarkably reduced.
[0125] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the following claims.
* * * * *