U.S. patent application number 13/176696 was filed with the patent office on 2011-10-27 for centrifugal micro-fluidic device and method for detecting analytes from liquid specimen.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to In Wook KIM.
Application Number | 20110263030 13/176696 |
Document ID | / |
Family ID | 44319952 |
Filed Date | 2011-10-27 |
United States Patent
Application |
20110263030 |
Kind Code |
A1 |
KIM; In Wook |
October 27, 2011 |
CENTRIFUGAL MICRO-FLUIDIC DEVICE AND METHOD FOR DETECTING ANALYTES
FROM LIQUID SPECIMEN
Abstract
A centrifugal micro-fluidic device detecting analytes in a
liquid specimen and a method of detection of analytes from a liquid
specimen using the micro-fluidic device are provided. Reaction
efficiency is increased using a repetitive flow of the liquid
specimen induced by an alternating combination of capillary force
and centrifugal force, thereby enhancing detection sensitivity.
Inventors: |
KIM; In Wook; (Seongnam-si,
KR) |
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
Suwon-si
KR
|
Family ID: |
44319952 |
Appl. No.: |
13/176696 |
Filed: |
July 5, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13004933 |
Jan 12, 2011 |
|
|
|
13176696 |
|
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|
Current U.S.
Class: |
436/45 ;
422/68.1 |
Current CPC
Class: |
G01N 2035/00495
20130101; G01N 33/54366 20130101; B01L 2200/10 20130101; B01L
2400/086 20130101; G01N 33/558 20130101; B01L 3/502738 20130101;
G01N 35/00069 20130101; B01L 2400/0409 20130101; Y10T 436/25375
20150115; B01L 2300/0867 20130101; B01L 2400/0406 20130101; Y10T
436/111666 20150115; B01L 3/50273 20130101; B01L 2400/088 20130101;
B01L 2300/0806 20130101 |
Class at
Publication: |
436/45 ;
422/68.1 |
International
Class: |
G01N 33/00 20060101
G01N033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 2010 |
KR |
10-2010-008392 |
Claims
1. A centrifugal micro-fluidic device comprising: at least one
micro-fluidic structure comprising a chamber and at least one
channel connected with the chamber; and a detection unit, wherein
the chamber comprises a reaction chamber in which a detectable
signal generator is combined with an analyte of a liquid specimen
to create a detectable signal generator-analyte complex, and an
analysis chamber located downstream from the reaction chamber,
wherein the reaction chamber comprises a porous material which
includes a detectable signal generator, wherein the analysis
chamber comprises a detection region where a capture binder is
combined with the detectable signal generator-analyte complex,
wherein the detection region includes one of porous membranes,
micro-pore structures and micro-pillars.
2. A method of analyzing an analyte in a liquid specimen, the
method comprising: injecting the liquid specimen into a
micro-fluidic structure of a micro-fluidic device; centrifuging the
liquid specimen to obtain a supernatant; transporting the
supernatant into a porous material installed in a reaction chamber
of the micro-fluidic structure by capillary action in which a
detectable signal generator is contained, wherein the flow of the
supernatant is temporarily stopped by capillary force of the porous
material; combining the analyte in the supernatant with the
detectable signal generator to create a detectable signal
generator-analyte complex; subjecting the micro-fluidic device to
centrifugation; transporting the detectable signal
generator-analyte complex into an analysis chamber of the
micro-fluidic structure, wherein the analysis chamber is located
downstream of the reaction chamber and comprises a detection region
to which a capture binder is fixed, and the detection region
comprises porous membranes, micro-pore structures or micro-pillars;
moving the detectable signal generator-analyte complex by capillary
force to an end of the analysis chamber; combining the detectable
signal generator-analyte complex in the supernatant with the
capture binder in the analysis chamber; applying centrifugal force
to the micro-fluidic device to deliver the supernatant moved to the
end of the analysis chamber to another end of the analysis chamber
and simultaneously combining the detectable signal
generator-analyte complex in the supernatant with the capture
binder in the analysis chamber; applying centrifugal force to the
micro-fluidic device to spin-dry the detection region of the
analysis chamber; and detecting the detectable signal
generator-analyte complex combined with the capture binder.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. application Ser.
No. 13/004,933, filed on Jan. 12, 2011, now pending, which claims
priority from Korean Patent Application No. 10-2010-008392, filed
on Jan. 29, 2010 in the Korean Intellectual Property Office, the
disclosures of which are both incorporated herein by reference.
BACKGROUND
[0002] 1. Field
[0003] Apparatuses and methods consistent with exemplary
embodiments relate generally to a centrifugal micro-fluidic device
for detecting analytes in a liquid specimen and a detection method
using the micro-fluidic device and, more particularly, to a
centrifugal micro-fluidic device for detection of analytes from a
liquid specimen with improved sensitivity. wherein a repeated flow
of a liquid specimen induced by both capillary force and
centrifugal force enhances reaction efficiency, as well as a method
for detection of analytes in a liquid specimen using the
micro-fluidic device.
[0004] 2. Description of the Related Art
[0005] In order to cause a fluid to flow or move in a micro-fluidic
structure of a micro-fluidic device, a driving pressure is
generally required. The driving pressure may be a capillary
pressure or pressure generated using an additional pump. In recent
years, clinical diagnostic analyzers have been proposed that are
designed to enable detection of a target material present in a
small amount of fluid in simple and economical ways. One example is
a centrifugal micro-fluidic device having a micro-fluidic structure
mounted on a circular disc-type rotational platform such as a
lab-on-disc and/or a lab compact disc ("CD").
[0006] Lab-on-disc, meaning "laboratory on a disk" is a CD-type
device in which various experimental units are integrated for
analysis of biomolecules used in a laboratory in order to execute
several experimental processes including, for example, isolation,
purification, mixing, labeling, assaying and/or washing of a sample
on a small disc. Upon introduction of a biological sample, such as
blood, into a micro-fluidic structure placed on a disc, the CD-type
device may advantageously transfer a fluid such as a biological
sample, a chemical reagent, etc. Centrifugal force alone may be
used to induce driving pressure and transport the fluid without
additional driving systems.
[0007] Recently, the use of a lap-on-a-chip' for blood analysis has
been investigated for its ability to rapidly obtain a variety of
information from blood samples collected from clinical cases. As a
result, a rapid-chip or a rapid-kit has been developed. For such a
rapid-chip or rapid-kit, several processes are executed in only a
reaction part of the rapid-chip or rapid-kit, including:
combination of a material to be analyzed (that is, an analyte) with
a detectable signal generator; combination of a composite of the
analyte and the detectable signal generator (referred to as
"detectable signal generator-analyte complex") with a capture
binder and washing thereof; and the like. However, since the
analyte is primarily combined with the labeling reagent, a large
amount of labeling reagent is required, although this requirement
is seldom satisfied in view of practical aspects. In addition, if
the analyte does not fully react with the labeling reagent, an
un-combined portion of the analyte and the detectable signal
generator may be combined with a capture binder present on a test
line, in turn competitively inhibiting the detectable signal
generator-analyte complex from being bonded to a control line or
test line. Furthermore, combination of the analyte and each reagent
is terminated within only a single fluid sample stream in one
direction, thus resulting in insufficient combination and causing
decrease in sensitivity and difficulties in quantitative analysis.
The kit does not have an active device for controlling a re-lysis
rate of the detectable signal generator and, therefore, the
detectable signal generator is excessively re-lysed by a constant
volume of a fluid sample flowing thereto, thus causing waste of the
detectable signal generator at an early stage. On the other hand,
re-lysis of the detectable signal generator is drastically reduced
in a later stage, thus entailing difficulties in sensitive
detection of the analyte.
SUMMARY
[0008] One or more exemplary embodiments provide a centrifugal
micro-fluidic device for detection of analytes from a liquid
specimen with improved sensitivity wherein a repeated flow of the
liquid specimen induced by a combination of capillary force and
centrifugal force enhances reaction efficiency, as well as a method
for detection of analytes from a liquid specimen using the
micro-fluidic device.
[0009] According to an aspect of an exemplary embodiment, there is
provided a centrifugal micro-fluidic device including: a rotational
body; at least one micro-fluidic structure including multiple
chambers, at least one channel through which the multiple chambers
are connected with one another and at least one valve opening and
closing the at least one channel; wherein the plurality of chambers
include a reaction chamber where a detectable signal generator is
combined with an analyte of a liquid specimen to create a
detectable signal generator-analyte complex, and an analysis
chamber located downstream from the reaction chamber; wherein the
analysis chamber includes a detection region where a capture binder
is combined with the detectable signal generator-analyte complex;
wherein the detection region includes one of porous membranes,
micro-pore structures and micro-pillars; and a detection unit.
[0010] According to an aspect of another exemplary embodiment,
there is provided a centrifugal micro-fluidic device including: at
least one micro-fluidic structure having multiple chambers, at
least one channel through which the multiple chambers are connected
and at least one valve for opening and closing the at least one
channel; wherein the plurality of chambers comprise a reaction
chamber where a detectable signal generator is combined with an
analyte of a liquid specimen to create a detectable signal
generator-analyte complex, and an analysis chamber located
downstream from the reaction chamber; wherein the analysis chamber
includes a detection region where a capture binder is combined with
the detectable signal generator-analyte complex; wherein the at
least one valve controls the transportation of the fluid between
the reaction chamber and the analysis chamber; wherein the
detection region includes one of porous membranes, micro-pore
structures and micro-pillars; and a detection unit detects
absorbance the detection region of the reaction chamber.
[0011] According to an aspect of another exemplary embodiment,
there is provided a centrifugal micro-fluidic device including: a
rotational body; at least one micro-fluidic structure having
multiple chambers, and at least one channel through which the
multiple chambers are connected together; wherein the plurality of
chambers include a reaction chamber where a detectable signal
generator is combined with an analyte of a liquid specimen to
create a detectable signal generator-analyte complex, and an
analysis chamber located downstream from the reaction chamber;
wherein the analysis chamber includes a detection region where a
capture binder is combined with the detectable signal
generator-analyte complex; wherein the detection region includes
one of porous membranes, micro-pore structures and micro-pillars;
and a detection unit which detects absorbance the detection region
of the reaction chamber.
[0012] The capture binder and the detectable signal generator may
be selected from deoxyribonucleic acid (DNA), oligonucleotide,
ribonucleic acid (RNA), RNA aptamer, peptide nucleic acid (PNA),
ligand, receptor, hapten, antigen and antibody; however, they are
not particularly limited thereto.
[0013] The analysis chamber may further include holder which
carries a fluid provided from the reaction chamber.
[0014] The detection region may contact the holder at one end of
the holder.
[0015] The detection region may further include a test region to
which the capture binder is fixed, as well as a control region
located downstream of the test region relative to a direction for
capillary action apart from the test region by a distance.
[0016] A section of the detection region including the test region
and the control region may be inclined in the direction of
capillary action.
[0017] The plurality of chambers may further include a stoppage
chamber which is located downstream of the analysis chamber
relative to a direction of centrifugal force to receive the liquid
specimen from the analysis chamber.
[0018] The detectable signal generator in the reaction chamber is
contained in a liquid or dried solid state.
[0019] The detectable signal generator may include polymeric beads,
metal colloids, enzymes, fluorescent materials, luminous materials,
super paramagnetic materials, materials containing lanthanum (III)
chelate, polymeric nano-particles, or radioactive isotopes.
[0020] The detection unit may detect and assay a detectable signal
generator-analyte complex combined with the capture binder.
[0021] The detection unit may include a light source unit and a
light receiving unit, such that the light receiving unit is aligned
with the light source unit to accept light emitted from the light
source unit that passes through the analysis chamber.
[0022] According to an aspect of another exemplary embodiment,
there is provided a method of analyzing an analyte in a liquid
specimen, including: injecting the liquid specimen into a
micro-fluidic structure of the micro-fluidic device, centrifuging
the liquid specimen to obtain a supernatant; transporting the
supernatant into a reaction chamber in which a detectable signal
generator is contained; combining the analyte in the supernatant
with the detectable signal generator to create a detectable signal
generator-analyte complex; subjecting the micro-fluidic device to
centrifugation; transporting the detectable signal
generator-analyte complex into an analysis chamber, wherein the
analysis chamber is located downstream of the reaction chamber, and
wherein the analysis chamber includes a detection region to which a
capture binder is fixed, and wherein the detection region includes
porous membranes, micro-pore structures or micro-pillars; moving
the and wherein the analysis chamber by capillary force to an end
of the analysis chamber; combining the detectable signal
generator-analyte complex in the supernatant with the capture
binder in the analysis chamber; applying centrifugal force to the
micro-fluidic device to deliver the supernatant moved to the end of
the analysis chamber to a front end of the analysis chamber and
simultaneously combining the detectable signal generator-analyte
complex in the supernatant with the capture binder in the analysis
chamber; and detecting the detectable signal generator-analyte
complex combined with the capture binder.
[0023] The movement of the supernatant from an end of the analysis
chamber to the other end of the analysis chamber may proceed at
least two times.
[0024] The analysis chamber may further include a holder which
carries a fluid provided from the reaction chamber.
[0025] The detection region may contact the holder at one end of
the holder.
[0026] For the centrifugal micro-fluidic device, the micro-fluidic
structure may further include a stoppage chamber which is located
downstream of the analysis chamber relative to a direction of
centrifugal force to receive the liquid specimen from the analysis
chamber.
[0027] The detectable signal generator in the reaction chamber is
contained in a liquid or dried solid state.
[0028] The detectable signal generator may include polymeric beads,
metal colloids, enzymes, fluorescent materials, luminous materials,
super paramagnetic materials, materials containing lanthanum (III)
chelate, polymeric nano-particles, or radioactive isotope
elements.
[0029] Before detecting the detectable signal generator-analyte
complex, the liquid specimen contained in the analysis chamber may
be transported into the stoppage chamber so as to stop a reaction
between the detectable signal generator-analyte complex and the
capture binder.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The above and/or other aspects will become apparent and more
readily appreciated from the following description of the exemplary
embodiments, taken in conjunction with the accompanying drawings,
of which:
[0031] FIG. 1 is a schematic view illustrating the construction of
a micro-fluidic device according to an exemplary embodiment;
[0032] FIG. 2 is a schematic view illustrating the construction of
a micro-fluidic structure in the micro-fluidic device shown in FIG.
1;
[0033] FIG. 3 is a detailed view illustrating a sample chamber;
[0034] FIG. 4 is a detailed view illustrating a sample separation
unit;
[0035] FIG. 5 is an enlarged view illustrating micro-pillars formed
in a detection region according to an exemplary embodiment;
[0036] FIG. 6 is a side view illustrating an analysis chamber
according to another exemplary embodiment;
[0037] FIG. 7 is a block diagram illustrating a test system
according to an exemplary embodiment; and
[0038] FIG. 8 is a flow chart explaining a method for detection of
an analyte from a liquid specimen using a micro-fluidic device
according to an exemplary embodiment.
DETAILED DESCRIPTION
[0039] Hereinafter, and practical methods thereof will be exemplary
embodiments will be described with reference to the accompanying
drawings. However, the inventive concept may be embodied in various
other forms, which are not particularly restricted to those
described herein.
[0040] One exemplary embodiment provides a centrifugal
micro-fluidic device for detection of an analyte from a liquid
specimen, which includes a rotational body; at least one
micro-fluidic structure having multiple chambers, at least one
channel through which the multiple chambers are connected together
and at least one valve for opening and closing the channel; and a
detection unit, wherein the device also has a reaction chamber for
receiving a detectable signal generator to be combined with the
analyte in the liquid specimen and an analysis chamber that is
located downstream of the reaction chamber and includes a detection
region to which a capture binder to be combined with a detectable
signal generator-analyte complex is fixed, and wherein a fluid
transported between the reaction chamber and the analysis chamber
is controlled by the above valve and the detection region includes
porous membranes, micro-pore structures or micro-pillars.
[0041] A test sample may include, for example, DNA,
oligonucleotide, RNA, PNA, ligand, receptor, antigen, antibody,
milk, urine, saliva, hair, a crop sample, a meat sample, an avian
sample, a livestock sample, a processed food sample, an oral cell,
a tissue sample, sperm, protein or other bio materials; however,
the test sample is not particularly limited thereto. Such a sample
may be used in a liquid or fluid state by dissolution using a
buffer solution. The analyte may include, for example, protein,
antigen, antibody, DNA or RNA, oligonucleotide, receptor, and the
like; although the analyte is not particularly limited thereto. For
a urine sample, the analyte may be blood, glucose, ascorbic acid,
ketone, protein, sugar, urobilinogen, bilirubin, etc.
[0042] FIG. 1 is a schematic view illustrating the construction of
a micro-fluidic device according to an exemplary embodiment, while
FIG. 2 is a schematic view illustrating the construction of a
micro-fluidic structure according to an exemplary embodiment.
[0043] A rotational body 10 used in one exemplary embodiment may
include a circular disc-type platform 20 (see FIG. 1). However, a
shape of the platform 20 is not particularly limited to a circular
disc form. The platform may be formed using acryl or other plastic
materials, each of which is easily formable and has a biologically
inactive surface. However, a raw material for fabrication of the
rotational body is not particularly limited and may include any
materials with chemical or biological stability, optical
transparency and/or mechanical workability.
[0044] At least one micro-fluidic structure 30 may be provided on
the platform. For instance, after partitioning the platform 20 into
several sections 30, 40, separate micro-fluidic structures 31, 41
may be placed independently of one another on the sections 30, 40,
respectively. FIG. 1 shows a particular platform 20 having two
micro-fluidic structures 31, 41 formed thereon.
[0045] The term "micro-fluidic structure" used herein refers to a
general structure which consists of a plurality of chambers,
channels and valves and induces a fluid flow, instead of a
particular structural substance. Therefore, the "micro-fluidic
structure" may form a specific unit with different functions or
performances according to features such as the arrangement of
chambers, channels and/or valves, and/or kinds of materials
received in the structure.
[0046] Accordingly, the micro-fluidic device may be widely used in
various applications, such as detection of various chemical
compounds, environmentally harmful substances, blood analysis,
urine testing, antigen-antibody response-based immunoassay, search
of novel drug candidates based on ligand-receptor binding, DNA/RNA
analysis, and so forth. Further, the micro-fluidic device may
simultaneously detect and analyze at least two analytes.
[0047] The platform may be fabricated using at least one material
selected from a variety of materials, such as plastic,
polymethylmethacrylate ("PMMA"), glass, mica, silica, a silica
wafer material, etc. The plastic material is used in view of
economic merits and simple workability. Potential plastic materials
may include polypropylene, polyacrylate, polyvinylalcohol,
polyethylene, polymethylmethacrylate, polycarbonate, etc.
[0048] A fluid sample, a buffer solution, a reactive solution, etc.
may be transported into separate chambers using centrifugal force
generated by rotation of the rotational body 10. The rotational
body 10 has a rotational driver D for high speed revolution (see
FIG. 7). Centrifugal force generated by rotation of the rotational
driver D may enable transportation and/or admixing of a sample.
[0049] FIG. 2 shows a sample chamber 100, a sample separation unit
200, a reaction chamber 300, and an analysis chamber 400.
[0050] The sample chamber 100 may provide a space to receive a
fluid-type sample such as blood. The sample separation unit 200 may
enable centrifugation of the sample into a supernatant (that is,
serum, plasma, etc.) and a precipitate (that is, blood cells). The
reaction chamber 300 and the analysis chamber 400 are structures
for detecting specific protein, glucose, cholesterol, uric acid,
creatinine, alcohol, etc. contained in the supernatant by
antigen-antibody response, ligand-receptor binding, and so
forth.
[0051] FIG. 3 is a detailed view illustrating the sample chamber
100. Referring to FIG. 3, the sample chamber 100 has a sample
introduction inlet 110 and a sample receiving unit 120. The sample
receiving unit 120 has an outlet 130 connected to the sample
separation unit 200 (not shown). Although not shown in the drawing,
the outlet 130 may be formed to generate capillary force, so as to
prevent a fluid sample from moving toward the sample separation
unit 200 when centrifugal force is not applied, as described below.
Alternatively, in order to control a flow of the fluid sample, a
valve may be mounted on the outlet 130. Furthermore, the sample
chamber 100 may have a cross-section increasing from the inlet 110
toward the outlet 130, enabling the sample contained in the sample
receiving unit 120 to easily flow toward the sample separation unit
200 by centrifugal force. In order to facilitate the flow of the
sample into the sample receiving unit 120 by injection pressure of
the sample through the inlet 110 and, in addition, to block a
reverse flow of the sample entered into the sample receiving unit
120 toward the inlet 110, an alternative structure to generate
capillary pressure may be placed between the inlet 110 and the
sample receiving unit 120. This alternative structure, such as a
capillary valve-type structure, will pass the sample through the
sample chamber 100 only when a desired pressure is applied.
[0052] The sample receiving unit 120 may have at least one
anti-reverse flow unit 140 in a direction crossing a sample flow
direction wherein the sample flows from the inlet 110 to the outlet
130. The anti-reverse flow unit 140 may be in a rib form. The
anti-reverse flow unit 140 creates resistance in the flow of the
sample, and as a result, inhibits a reverse flow of the sample from
the sample receiving unit 120 to the inlet 110.
[0053] Since transportation of the sample from the sample chamber
100 to the sample separation unit 200 utilizes centrifugal force by
rotation of the rotational body 10, the sample receiving unit 200
is duly located more outwardly than the sample chamber 100. The
sample separation unit 200 for centrifugation of the sample may be
configured in different forms, and an exemplary embodiment of the
sample separation unit 200 is shown in FIG. 4. Referring to FIG. 4,
the sample separation unit 200 may include a channel-type
supernatant collector 210 outwardly extending from the sample
chamber 100 and a precipitate collector 220, which is a space
formed at an end of the supernatant collector 210 to collect a
precipitate with relatively high specific gravity. The supernatant
collector 210 has a sample dispenser channel 230 to distribute the
supernatant into the reaction chamber 300 (not shown). The flow of
the sample passing through the sample dispenser channel 230 may be
controlled by a valve 231. The valve 231 may be any type of
micro-fluidic valve. For instance, the valve 231 may comprise a
so-called "normally closed valve" wherein a channel of the valve is
closed to prevent a fluid from flowing unless the valve opens by an
external power source.
[0054] Referring back to FIG. 2, a supernatant metering chamber 250
may be placed between the sample separation unit 200 and the
reaction chamber 300, so as to measure an amount of the
supernatant. A volume of the supernatant metering chamber 250 may
be sufficient to carry a certain amount of the supernatant required
for testing. A valve 251 is mounted on an outlet of the supernatant
metering chamber 250, so as to control the fluid flow. The valve
251 may be a normally-closed valve identical to the valve 231. The
supernatant metering chamber 250 is connected to the reaction
chamber 300 through a channel 252. Although not shown in the
drawing, an alternative chamber and an additional fluid channel may
be provided between the sample dispenser channel 230 and the
supernatant metering chamber 250, so as to receive excess sample in
a liquid phase remaining after metering.
[0055] First and second buffer chambers 310 and 320 may receive a
reactant (that is, a reactive solution) required for
antigen-antibody response or a biochemical reaction (such as
ligand-receptor binding).
[0056] The first buffer chamber 310 receives a first buffer. The
first buffer may include, for example, a conjugate buffer for
sandwich immunoassay, a competitive protein-containing buffer for
competitive immunoassay, a buffer that contains various enzymes
including, for example, polymerase and primer for DNA
amplification, and so forth.
[0057] The first buffer chamber 310 is connected to a first vent
chamber 313. The first vent chamber 313 forms a vent path to
communicate the first buffer chamber 310 with external air, thus
easily discharging the first buffer contained in the first buffer
chamber 310. A valve 314 is placed between the first buffer chamber
310 and the first vent chamber 313. Another valve 311 is mounted on
an outlet of the first buffer chamber 310. Each of such valves 311
and 314 may be normally closed valves as described above. By
introducing the first buffer into the first buffer chamber 310 and
installing the valves 311 and 314, the first buffer chamber 310 may
remain sealed until the valves 311 and 314 are opened. According to
another exemplary embodiment, a metering chamber (not shown) may be
provided at the outlet of the first buffer chamber 310 in order to
provide a constant amount of first buffer required for testing into
the reaction chamber 300. If a valve (not shown) is mounted on an
outlet of the metering chamber (not shown), the first buffer flow
may be controlled. If the metering chamber is not used, the first
buffer may be directly fed from the first buffer chamber 310 to the
reaction chamber 300 by opening the valve 311 mounted on the outlet
of the first buffer chamber 310.
[0058] The second buffer chamber 320 receives a second buffer. The
second buffer may include, for example, a substrate buffer to
express a specific color by reaction of the substrate with a
product of conjugate reaction or competitive reaction, a buffer
that contains various enzymes required for DNA hybridization, and
so forth. The second buffer chamber 320 is substantially the same
as the first buffer chamber 310 except that the second buffer
received therein is different from the first buffer, and therefore
a detailed description of the second buffer chamber 320 will be
omitted for brevity.
[0059] Although one exemplary embodiment describes the
micro-fluidic structure consisting of two buffer chambers 310 and
320, such structure may have only one buffer chamber or at least
three buffer chambers, based on reaction types.
[0060] In another exemplary embodiment, a washer chamber 330 may
contain a washing buffer to rinse a residue remaining after a
reaction in the reaction chamber 300. The washer chamber 330 is
connected with a third vent chamber 333. The third vent chamber 333
forms another vent path to communicate the washer chamber 330 with
external air, thus easily discharging the washer buffer contained
in the washer chamber 330. A valve 334 is placed between the washer
chamber 330 and the third vent chamber 333. The washer chamber 330
is connected to the reaction chamber 300 through another valve 331.
Each of such valves 331 and 334 may be a normally closed valve as
described above.
[0061] The reaction chamber 300 receives the supernatant from the
supernatant metering chamber 250 through a channel 252. The
reaction chamber 300 may contain a detectable signal generator
present in a liquid or solid phase.
[0062] When the detectable signal generator in a solid phase is
present in the reaction chamber 300, the detectable signal
generator may be temporarily fixed to an inner wall of the reaction
chamber 300 or a porous pad therein. That is, the detectable signal
generator fixed to the reaction chamber 300 is lysed by penetration
of the supernatant, at which point the lysed binder is combined
with an analyte contained in the supernatant. The combined
detectable signal generator-analyte becomes a movable product. If
the supernatant flows into the reaction chamber 300, the detectable
signal generator is excessively re-lysed at an early stage while
re-lysis of the detectable signal generator is drastically reduced
at a later stage. Conventional technologies have problems with
deterioration in reproducibility of test results and
concentration-response signal characteristics of analytes,
depending on variation in re-lysis of the detectable signal
generator and/or outflow rate of the detectable signal generator,
since both a capillary force acting unit and another unit
containing the detectable signal generator are co-present in a
physical space. Such technologies also have restrictions wherein
the detectable signal generator must be in a solid phase and fixed
to the physical space. On the contrary, the exemplary embodiment
separately uses a reaction chamber 300 containing the detectable
signal generator and an analysis chamber 400 for capillary action,
described below, thereby eliminating influences of re-lysis of a
detectable signal generator and/or outflow rate of the detectable
signal generator on capillary force. In addition, as a fluid sample
(that is, a liquid specimen) is fed into the analysis chamber 400
after completing combination of the detectable signal generator
with the analyte in a physically separated space, the detectable
signal generator may be preferably present in either a liquid or a
solid state.
[0063] A detectable signal generator refers to a material
specifically reacting with an analyte provided in the reaction
chamber 300 by any typical method. Examples of such detectable
signal generator vary depending on the types of analytes. For
instance, for antibody A as the analyte, the detectable signal
generator may be a conjugate such as an antigen or antibody
pre-linked with a labeling material such as a fluorescent material,
wherein the antibody A and the detectable signal generator are
first combined in the reaction chamber 300, a conjugate formed of
the antibody A and the fluorescent material is fixed to the
analysis chamber 400, using an antigen corresponding to the
antibody A, followed by use of the conjugate for detection.
[0064] Labels of the detectable signal generator may include, for
example, polymeric beads, metal colloids such as gold colloids or
silver colloids, enzymes such as peroxidase, fluorescent materials,
luminous materials, super paramagnetic materials, materials
containing lanthanum (III) chelate, polymeric nano-particles, and
radioactive isotope elements. However, the labels of the detectable
signal generator are not particularly limited thereto.
[0065] The reaction chamber 300 may have a waste chamber 360 to
store residues remaining after the reaction which were rinsed using
a washer buffer in the washer chamber 330, impurities to be
withdrawn, and the like. The impurities containing an un-combined
detectable signal generator and/or analyte are moved to the waste
chamber 360. Therefore, for example, for non-competitive analysis
such as detection of specific antibodies, an un-combined detectable
signal generator or analyte in the reaction chamber 300 is neither
shifted to the analysis chamber 400 nor combined with a capture
binder permanently fixed to a test region or a control region
described below. Accordingly, a detectable signal generator-analyte
complex is not bonded to the test region or the control region,
thereby avoiding competitive inhibition of such bonding. Moreover,
since an un-combined portion of the analyte is separated into the
waste chamber 360, a "high-dose Hook effect" caused by a high
concentration analyte is not observed. The waste chamber 360 is
connected to the reaction chamber 300 through a channel 362. The
channel 362 has a valve 361 which may be a normally closed valve
described above.
[0066] The analysis chamber 400 is connected to the reaction
chamber 300 through a valve 305 and receives a fluid from the
reaction chamber 300 after the reaction is terminated.
[0067] The analysis chamber 400 is provided for antigen-antibody
response or a specific biochemical reaction between
bio-materials.
[0068] The analysis chamber 400 includes a holder 410 for receiving
a fluid from the reaction chamber 300 after terminating a reaction;
and a detection region 420 under capillary action, which consists
of porous membranes, micro-pore structures or micro-pillars. The
detection region 420 includes a test region 430 to which a capture
binder is directly or indirectly fixed in order to assay analytes.
The analysis chamber 400 may further have a control region 440 to
which another capture binder, independent of the capture binder
permanently fixed to the test region 430, is permanently fixed.
[0069] An end of the detection region 420 is extended to the holder
410 and, when a fluid fed from the reaction chamber 300 fills the
holder 410, the extended end of the detection region 420 is
submerged in the fluid. When fully charging the holder 410 with
fluid, capillary force is applied in Direction A shown in FIG. 2,
and a detectable signal generator-analyte complex moves along the
detection region 420 in the same direction, that is, Direction A.
The detectable signal generator-analyte complex is combined with a
capture binder which is permanently fixed to the test region 430
and the control region 440 by antigen-antibody response or a
specific biochemical reaction between biological materials. As a
result, the detectable signal generator-analyte complex is
entrapped in the test region 430 and the control region 440. After
the fluid is completely shifted to the regions 430 and 440 by
capillary force, the fluid is again delivered back into the holder
410 by centrifugal force applied in Direction B shown in FIG. 2,
wherein the centrifugal force is generated by rotation of the
micro-fluidic device. The direction of centrifugal force, Direction
B, is opposite to the direction of capillary action, Direction A.
Accordingly, compared to any conventional technique using capillary
force applied in a single direction to react the fluid with a fixed
reagent, a 2-fold increase in reaction time is achieved, in turn,
remarkably enhancing reaction sensitivity.
[0070] A reaction cycle of the application of capillary force
(Direction A) and centrifugal force (Direction B) is not limited to
only one cycle but, after completely transporting the fluid back
into the holder 410 by centrifugal force and stopping rotation of
the micro-fluidic device, a portion of the detectable signal
generator-analyte complex which was not combined with the capture
binder is again combined with the other capture binder permanently
fixed to the test region 430 and the control region 440 by
capillary force in Direction A. After the fluid is completely
shifted to the regions 430, 440 by a second application of
capillary action, the fluid may be again delivered into the holder
410 using a second application of centrifugal force generated by
rotation of the micro-fluidic device so that a portion of the
analyte-first reagent complex which was not combined by the second
capillary action may be repeatedly subjected to reaction. In one
exemplary embodiment, a reaction cycle is repeated for the desired
number of repetitions so as to sufficiently conduct the reaction,
thus considerably improving detection sensitivity of analytes.
[0071] The analysis chamber 400 has a stoppage chamber 460 to
receive a portion of the fluid which was not combined with the
capture binder after the reaction in the test region 430 and
control region 440. The stoppage chamber 460 is connected to the
analysis chamber 400 via a channel 462. A valve 461 is mounted on
the channel 462. The valve 461 may be a normally closed valve
described above. After the reaction is sufficiently conducted, the
valve 461 is opened and the fluid contained in the analysis chamber
400 is completely shifted to the stoppage chamber 460 using
centrifugal force generated by rotation of the micro-fluidic
device, thus terminating the reaction.
[0072] The capture binder refers to a capture probe to assay
analytes and may include various materials such as antigen,
antibody, enzyme, DNA, RNA, and the like depending on the subject
analyte materials to be analyzed. For instance, if the analyte is a
carbamate-based insecticide, the capture binder may be
acetylcholine esterase (AChE), while if the analyte is an antigent,
the capture binder may be a capture antibody for the antigen.
[0073] The detection region 420 to which the capillary force is
applied must be optically transparent, and may have a cross-section
in a circular or rectangular form. For the detection region 420
with a circular cross-section, an internal diameter of a capillary
tube may range from approximately several micrometers to
approximately 1 millimeter. A size of the capillary tube may be
defined within a desired range sufficient to determine a red blood
cell ratio, that is, hematocrit. The detection region 420 may be
formed by any suitable materials as long as they have a small
cavity volume and comprise very fine pores with a high bulk
density. Examples of such materials may include porous membranes,
micro-pore structures, micro-pillars, and the like. FIG. 5 shows
micro-pillars 502 used for preparing the detection region 420.
[0074] FIG. 6 shows an analysis chamber 400' according to another
exemplary embodiment. Referring to FIG. 6, a detection region 420'
having a test region 430' and a control region 440' is partially
inclined relative to the Direction A for capillary action. More
particularly, an end of the detection region 420' coming into
contact with a holder 410' forms an upward inclination unit 470 in
which the test region 430' and the control region 440' are present,
while the other unit 480 of the detection region 420' is straight.
The reason behind such configuration is that the end 490 of the
detection region 420' coming into contact with the holder 410' is
located below the test region 430' and the control region 440' so
as to prevent overflow of the fluid exceeding capillary force by
virtue of gravity.
[0075] Another exemplary embodiment provides a centrifugal
micro-fluidic device for detection of an analyte from a liquid
specimen, including: at least one micro-fluidic structure having
multiple chambers, at least one channel through which the multiple
chambers are connected together, and at least one valve for opening
and closing the at least one channel; and a detection unit, wherein
the device also has a reaction chamber for receiving a detectable
signal generator to be combined with an analyte in the liquid
specimen and an analysis chamber that is located downstream of the
reaction chamber and includes a detection region to which a capture
binder to be combined with a detectable signal generator-analyte
complex is fixed, and wherein a fluid transported between the
reaction chamber and the analysis chamber is controlled by the at
least one valve, and wherein the detection region includes porous
membranes, micro-pore structures or micro-pillars.
[0076] This exemplary embodiment is substantially identical to the
above-described exemplary embodiment, except that the micro-fluidic
structure is mounted on the micro-fluidic device. Hereinafter,
particular characteristics and/or technical configurations of the
above micro-fluidic device different from those described in the
previous exemplary embodiment will be explained, while a detailed
description of the same conditions may be omitted for brevity.
[0077] After an analyte contained in a fluid sample (that is, the
liquid specimen) has been completely combined with a detectable
signal generator in a reaction chamber 300, a valve 305 located
between the reaction chamber 300 and an analysis chamber 400 is
opened. Then, the fluid sample containing a detectable signal
generator-analyte complex is delivered into a holder 410 of the
analysis chamber 400. After filling the holder 410 with the fluid
sample, the fluid sample moves along a detection region 420 by
capillary action, wherein an end of the holder 410 comes into
contact with the detection region 420. While moving along the
detection region 420 in Direction A shown in FIG. 2, the detectable
signal generator-analyte complex is combined with a capture binder
permanently fixed to a test region 430 and a control region 440,
for example by antigen-antibody response or a specific biochemical
reaction between biomaterials.
[0078] As described above, the detectable signal generator may be
present in a liquid or solid phase in the reaction chamber 300.
When the detectable signal generator is present in a solid phase,
the detectable signal generator fixed to the reaction chamber 300
is lysed by penetration of a supernatant, and the lysed binder is
then combined with an analyte contained in the supernatant. The
combined detectable signal generator-analyte becomes a movable
product.
[0079] As described above, the movable product is separated into a
detectable signal generator-containing portion and a capillary
force-acting portion by physical separation, wherein the detectable
signal generator-containing portion is entered into the reaction
chamber 300 while the capillary force-acting portion is received in
the analysis chamber 400. As a result, influences of re-lysis of
the detectable signal generator and/or outflow rate of the
detectable signal generator on capillary force may be favorably
excluded. Furthermore, since the fluid sample is fed into the
analysis chamber 400 after completing combination of the detectable
signal generator with the analyte in a physically separated space,
the detectable signal generator may be preferably present in either
a liquid or a solid state. Transportation of the fluid sample
containing a detectable signal generator-analyte complex from the
reaction chamber 300 to the analysis chamber 400 is duly controlled
by opening and closing a valve 305.
[0080] FIG. 7 is a block diagram illustrating a test system,
according to an exemplary embodiment.
[0081] Such a test system of the above exemplary embodiment
includes a rotational driver D for rotating a disc-type
micro-fluidic device 1, a valve switching unit E, a detection unit
30, an output unit 40, a diagnosis database (DB) 50, and a control
unit 60 for controlling individual devices described above.
[0082] The rotational driver D rotates the disc-type micro-fluidic
device 1 in order to apply centrifugal force thereto, enabling
centrifugation of a sample and movement of a fluid, and also stops
and rotates the same device 1 in order to move the analysis chamber
400 (see FIG. 2) to a desired position.
[0083] Although not shown in the drawing, the rotational driver D
may further include a motor driving device for controlling an
angular position of the disc type micro-fluidic device 1. For
example, the motor driving device may have a stepper motor or a
direct current (DC) motor.
[0084] The valve switching unit E is provided for opening and
closing at least one valve (not shown) of the disc type
micro-fluidic device 1, and includes an external energy source E1
and a movement unit E2 to move the external energy source E1 to any
valve required to be opened.
[0085] The external energy source E1 may be selected from a laser
source radiating a laser beam, a light emitting diode ("LED")
radiating visible or infrared light, a xenon lamp, etc. In
particular, the laser source may have at least one laser diode
(LD).
[0086] The movement unit E2 may further include a driving motor
(not shown) and a gear unit (not shown) equipped with the external
energy source E1 to move the external energy source E1 above a
valve required to be opened by rotation of the driving motor.
[0087] The detection unit 30 may be installed in plural to
determine absorbance of the reaction chamber, and in one exemplary
embodiment includes at least one light emission unit 31 and at
least one light receiving unit 32 which is aligned with the light
emission unit 31 to receive light penetrating the detection region
420 of the analysis chamber 400 (see FIG. 2) on the micro-fluidic
device 1.
[0088] The light emission unit 31 may be a light source flashing at
a specific frequency including, for example, a semiconductor light
emitting device such as an LED or a laser diode (LD), a gas
discharge lamp such as a halogen lamp or a xenon lamp, etc.
[0089] The light emission unit 31 is placed at a location above the
micro-fluidic device 1 at which light emitted from the light
emission unit 31 passes through the analysis chamber 400 and
reaches the light receiving unit 32.
[0090] The light receiving unit 32 generates electrical signals
according to an intensity of incident light and adopts, for
example, a depletion layer photodiode, avalanche photodiode (APD),
photomultiplier tube (PMT), etc.
[0091] In the present exemplary embodiment, the light emission unit
31 is located above the disc type micro-fluidic device 1, while the
light receiving unit 32 is positioned below the disc type
micro-fluidic device 1; however, the positions of these units may
be switched. Also, a light path may be adjusted using a reflecting
mirror or a light guide member (not shown).
[0092] The control unit 60 controls the rotational driver D, the
valve switching unit E and/or the detection unit 30 to smoothly
conduct operation of the test system, searches the diagnostic DB 50
and uses absorbance detected from the detection unit 30 and a
standard curve stored in the diagnostic DB 50 so as to determine a
concentration of an analyte in the supernatant contained in the
analysis chamber 400 of the micro-fluidic device 1.
[0093] The output unit 40 outputs diagnosis results and information
as to whether the diagnosis is completed or not, and may include a
visible output device such a liquid crystal display (LCD), an audio
output device such as a speaker, or an audiovisual output
device.
[0094] The following description will be given of a method of
detection of analytes in a liquid specimen, using the micro-fluidic
device. FIG. 8 is a flow chart illustrating a method of detection
of an analyte in a liquid specimen, using the micro-fluidic device,
according to an exemplary embodiment. In this non-limiting
exemplary embodiment, a process for blood analysis will be
described in detail.
[0095] For example, whole blood sampled from a subject to be tested
is introduced into a sample chamber 100 (S101), and the
micro-fluidic device 1 is mounted on the rotational driver D.
[0096] Next, rotating the micro-fluidic device 1 at a low speed,
the blood sample is delivered from the sample chamber 100 to the
sample separation unit 200. The low speed may be, in one exemplary
embodiment, a revolution speed generating centrifugal force
suitable for moving a fluid. For example, the micro-fluidic device
1 may rotate with an accelerated velocity of approximately 1800
revolutions per minute for 11 seconds. By centrifugal force, the
sample moves from the sample chamber 100 to the sample separation
unit 200. The sample is transported from the sample chamber 100 to
the sample separation unit 200 by centrifugal force.
[0097] Then, a centrifuging process is conducted (S102). The
rotational driver D rotates the micro-fluidic device 1 at a high
speed. Such high speed may be a revolution speed separating the
blood into a serum or plasma as a supernatant and a precipitate
(blood cells). For example, the micro-fluidic device 1 may rotate
with an accelerated velocity of approximately 3600 rpms for about
160 seconds. As a result, relatively heavy blood cells are moved
into the precipitate collector 220 while the supernatant remains in
the supernatant collector 210.
[0098] Using the valve switching unit E, the closed valve 231 is
opened. The rotational driver D rotates the micro-fluidic device 1
to generate centrifugal force. This centrifugal force causes the
supernatant to move from the supernatant collector 210 to the
supernatant metering chamber 250 via the channel 230. Since the
valve 251 at an outlet of the supernatant metering chamber 250 is
closed, the supernatant fills the supernatant metering chamber 250.
Accordingly, if an amount of the supernatant is sufficient, the
supernatant is contained in the supernatant metering chamber 250 in
an amount corresponding to a volume of the supernatant metering
chamber 250.
[0099] Next, the valve 251 is opened using the valve switching unit
E, and the supernatant moves from the supernatant metering chamber
250 to the reaction chamber 300 by rotation of the micro-fluidic
device 1. The rotational driver D may shake the micro-fluidic
device 1 several times in right and left (clockwise and
counter-clockwise) directions in order to combine the detectable
signal generator with the analyte contained in the supernatant. As
a result, a fluid sample (that is, a liquid specimen) containing a
detectable signal generator-analyte complex is created in the
reaction chamber 300 (S103).
[0100] Subsequently, by opening the valve 305 and rotating the
micro-fluidic device, the fluid sample is moved into the holder 410
of the analysis chamber 400. After filling the holder 410 with the
fluid sample, an end of the detection region 420 comes into contact
with the fluid sample contained in the holder 410, in turn enabling
capillary transfer of the fluid sample in the detection region 420
or 420', which consists of porous membranes, micro-pore structures
or micro-pillars. The fluid sample containing the detectable signal
generator-analyte complex moves along the detection region 420 or
420', and the detectable signal generator-analyte complex is
combined with a capture binder permanently fixed to the test region
430 or 430' (S104). After the fluid sample completely passes
through the detection region 420 or 420', the rotational driver D
rotates the micro-fluidic device in order to pass the fluid sample
back again through the detection region 420 or 420' by centrifugal
force. Here, a portion of the detectable signal generator-analyte
complex which was not combined with the capture binder by capillary
force may be combined with the capture binder (S105). Therefore,
compared to the conventional technique wherein an antigen-antibody
response and/or a biochemical reaction is terminated only after
fluid flow in a single direction, a reaction time in the present
exemplary embodiment is remarkably extended, in turn, enhancing
reaction sensitivity. In addition, as described above, the cycle of
application of capillary force and centrifugal force used in the
exemplary embodiment is not limited to one cycle, but may be
repeated for the desired number of cycles, so as to sufficiently
conduct the reaction. In other words, when rotation of the
micro-fluidic device is stopped after complete delivery of the
fluid sample into the holder 410 by centrifugal force, the fluid
sample flows again along the detection region 420 by capillary
action (S 104). After complete movement of the fluid sample along
the detection region 420, the fluid sample may be returned to the
holder 410 using the centrifugal force generated by rotating the
micro-fluidic device once more (S 105).
[0101] When it is determined that the reaction is sufficiently
conducted ("YES" in S106), the valve 461 connected with the holder
410 of the analysis chamber 400 is opened and the fluid sample is
transported into the stoppage chamber 460 through channel 462 by
rotation of the micro-fluidic device. After transportation of the
fluid sample to the stoppage chamber 460, the reaction to combine
the detectable signal generator-analyte complex with the capture
binder is terminated and does not proceed any further (S107).
Lastly, using the detection unit 30, absorbance of the detection
region 420 in the analysis chamber 400 is determined. For analysis
of end points, the absorbance is repeatedly measured at a defined
distances to determine an absorbance during a saturated reaction.
Based on a relationship between absorbance and concentration stored
in the diagnostic DB 340, a concentration of each of substances to
be analyzed is calculated.
[0102] Although a few exemplary embodiments have been shown and
described in conjunction with accompanying drawings, it is clearly
understood that the exemplary embodiments have been proposed for
illustrative purpose only and do not particularly restrict the
scope of the inventive concept. Accordingly, it will be appreciated
by those skilled in the art that various substitutions, variations
and/or modifications may be made in these exemplary embodiments,
and such exemplary embodiments are not particularly restricted to
particular configurations and/or arrangements described or
illustrated above.
* * * * *