U.S. patent application number 10/960890 was filed with the patent office on 2005-09-22 for pneumatic valve interface for use in microfluidic structures.
This patent application is currently assigned to Micronics, Inc.. Invention is credited to Hayenga, Jon W., Saltsman, Patrick, Weigl, Bernhard H..
Application Number | 20050205816 10/960890 |
Document ID | / |
Family ID | 23076003 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050205816 |
Kind Code |
A1 |
Hayenga, Jon W. ; et
al. |
September 22, 2005 |
Pneumatic valve interface for use in microfluidic structures
Abstract
A pneumatic valve for use in laminated plastic microfluidic
structures. This zero or low dead volume valve allows flow through
microfluidic channels for use in mixing, dilution, particulate
suspension and other techniques necessary for flow control in
analytical devices.
Inventors: |
Hayenga, Jon W.; (Redmond,
WA) ; Saltsman, Patrick; (Seattle, WA) ;
Weigl, Bernhard H.; (Seattle, WA) |
Correspondence
Address: |
SEED INTELLECTUAL PROPERTY LAW GROUP PLLC
701 FIFTH AVE
SUITE 6300
SEATTLE
WA
98104-7092
US
|
Assignee: |
Micronics, Inc.
Redmond
WA
|
Family ID: |
23076003 |
Appl. No.: |
10/960890 |
Filed: |
October 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10960890 |
Oct 6, 2004 |
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10114890 |
Apr 3, 2002 |
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60281114 |
Apr 3, 2001 |
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Current U.S.
Class: |
251/61.1 |
Current CPC
Class: |
B01L 2400/0406 20130101;
B01L 3/502761 20130101; F16K 2099/008 20130101; G01N 2001/4016
20130101; B01D 21/0012 20130101; F16K 99/0059 20130101; B01L
2200/028 20130101; G01N 2015/1411 20130101; B01L 2300/0829
20130101; G01N 2015/1486 20130101; Y10T 436/2575 20150115; B01L
3/502738 20130101; B01L 2200/027 20130101; F16K 99/0025 20130101;
B01L 2300/0861 20130101; Y10T 436/25375 20150115; B01L 2200/0636
20130101; G01N 2015/0288 20130101; B01L 3/502746 20130101; G01N
2015/144 20130101; B01L 3/502707 20130101; B01L 3/502776 20130101;
B01L 2300/0883 20130101; G01N 2035/00247 20130101; B01L 3/502753
20130101; G01N 2015/1413 20130101; B01L 2200/0668 20130101; B01L
2400/084 20130101; B01D 21/283 20130101; B01L 2400/0487 20130101;
F16K 7/17 20130101; F16K 99/0001 20130101; G01N 15/1456 20130101;
B01L 2400/0457 20130101; A61M 2206/11 20130101; G01N 2001/4061
20130101; B01L 3/50273 20130101; B01L 2400/0436 20130101; A61M 1/14
20130101; B01L 2200/0647 20130101; B01L 2300/0874 20130101; F16K
99/0015 20130101; G01N 15/0255 20130101; G01N 2001/4094 20130101;
G01N 15/05 20130101; F16K 2099/0084 20130101; B01L 3/5027
20130101 |
Class at
Publication: |
251/061.1 |
International
Class: |
F16K 031/145 |
Claims
What is claimed is:
1. A device for controlling flow in microfluidic devices
comprising: a first substrate having at least one microfluidic
structure manufactured therein; a first flexible sheet placed on
top of at least a portion of said microfluidic structure; and means
for creating a pressure differential onto said first flexible sheet
such that a portion of said sheet moves in relationship to said
microfluidic structure wherein the cross-section of said
microfluidic structure is altered at least in one dimension such
that the fluid resistance in said microfluidic structure is
altered.
2. The device of claim 1 further comprising a second microfluidic
structure on the opposite side of said first flexible sheet for
transmitting pressure through air or fluid flow onto a specific
location of said first flexible sheet such that a portion of said
sheet moves in relationship to said microfluidic structure such
that the cross-section of said microfluidic structure is altered at
least in one dimension such that the fluid resistance in said
microfluidic structure is altered.
3. A device for controlling flow in microfluidic devices,
comprising: a first substrate having at least one microfluidic
structure manufactured therein; a first flexible sheet placed on
top of a at least a portion of said microfluidic structure; and
means for creating pressure onto multiple, individually addressable
locations on said first flexible sheet such that one or more
potions of said sheet move in relationship to said microfluidic
structure such that the cross-section of said microfluidic
structure is altered at least in one dimension in one or more
locations such that the fluid resistance in said microfluidic
structure is altered in one or more locations such that fluid flow
through said microfluidic structure can be directed or altered.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application claims benefit from U.S. provisional
Patent Application Ser. No. 60/281,114, filed Apr. 3, 2001, which
application is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates generally to microscale devices for
performing analytical testing and, in particular, to a valve
interface for use in laminated microfluidic structures.
[0004] 2. Description of the Prior Art
[0005] Microfluidic devices have recently become popular for
performing analytical testing. Using tools developed by the
semiconductor industry to miniaturize electronics, it has become
possible to fabricate intricate fluid systems which can be
inexpensively mass produced. Systems have been developed to perform
a variety of analytical techniques for the acquisition of
information for the medical field.
[0006] Microfluidic devices may be constructed in a multi-layer
laminated structure where each layer has channels and structures
fabricated from a laminate material to form microscale voids or
channels where fluids flow. A microscale channel is generally
defined as a fluid passage which has at least one internal
cross-sectional dimension that is less than 500 .mu.m and typically
between about 0.1 .mu.m and about 500 .mu.m. The control and
pumping of fluids through these channels is affected by either
external pressurized fluid forced into the laminate, or by
structures located within the laminate.
[0007] U.S. Pat. No. 5,716,852 teaches a method for analyzing the
presence and concentration of small particles in a flow cell using
diffusion principles. This patent, the disclosure of which is
incorporated herein by reference, discloses a channel cell system
for detecting the presence of analyte particles in a sample stream
using a laminar flow channel having at least two inlet means which
provide an indicator stream and a sample stream, where the laminar
flow channel has a depth sufficiently small to allow laminar flow
of the streams and length sufficient to allow diffusion of
particles of the analyte into the indicator stream to form a
detection area, and having an outlet out of the channel to form a
single mixed stream. This device, which is known at a T-Sensor, may
contain an external detecting means for detecting changes in the
indicator stream. This detecting means may be provided by any means
known in the art, including optical means such as optical
spectroscopy, or absorption spectroscopy of fluorescence.
[0008] U.S. Pat. No. 5,932,100, which patent is also incorporated
herein by reference, teaches another method for analyzing particles
within microfluidic channels using diffusion principles. A mixture
of particles suspended in a sample stream enters an extraction
channel from one upper arm of a structure, which comprises
microchannels in the shape of an "H". An extraction stream (a
dilution stream) enters from the lower arm on the same side of the
extraction channel and due to the size of the microfluidic
extraction channel, the flow is laminar and the streams do not mix.
The sample stream exits as a by-product stream at the upper arm at
the end of the extraction channel, while the extraction stream
exits as a product stream at the lower arm. While the streams are
in parallel laminar flow in the extraction channel, particles
having a greater diffusion coefficient (smaller particles such as
albumin, sugars, and small ions) have time to diffuse into the
extraction stream, while the larger particles (blood cells) remain
in the sample stream. Particles in the exiting extraction stream
(now called the product stream) may be analyzed without
interference from the larger particles. This microfluidic
structure, commonly known as an "H-Filter," can be used for
extracting desired particles from a sample stream containing those
particles.
[0009] Several types of valves are commonly used for fluid
management in flow systems. Flap valves, ball-in-socket valves, and
tapered wedge valves are a few of the valve types existing in the
macroscale domain of fluid control. However, in the microscale
field, where flow channels are often the size of a human hair
(approximately 100 microns in diameter), there are special needs
and uses for valves which are unique to microscale systems,
especially microfluidic devices incorporating fluids with various
concentrations of particulates in suspension. Special challenges
involve mixing, dilution, fluidic circuit isolation, and
anti-sediment techniques when employing microscale channels within
a device. The incorporation of a simple compact microfluidic valve
within microscale devices addresses these potential problems while
maintaining high density of fluidic structure within the device,
and eliminating the need for active valve actuation in many
cases.
[0010] Many different types of valves for use in controlling fluids
in microscale devices have been developed. U.S. Pat. No. 4,895,500,
which issued on Jan. 23, 1990, describes a silicon micromechanical
non-reverse valve which consists of a cantilever beam extending
over a cavity and integrally formed with the silicon wafer such
that the beam can be shifted to control flow within channels of the
microfluidic structure.
[0011] U.S. Pat. No. 5,443,890, which issued Aug. 22, 1995 to
Pharmacia Biosensor AB, describes a sealing device in a
microfluidic channel assembly having first and second flat surface
members which when pressed against each other define at least part
of a microfluidic channel system between them.
[0012] U.S. Pat. No. 5,593,130, which issued on Jan. 14, 1997 to
Pharmacia Biosensor AB, describes a valve for use in microfluidic
structures in which the material fatigue of the flexible valve
membrane and the valve seat is minimized by a two-step seat
construction and the fact that both the membrane and the seat are
constructed from elastic material.
[0013] U.S. Pat. No. 5,932,799, which issued Aug. 3, 1999 to YSI
Incorporated, teaches a microfluidic analyzer module having a
plurality of channel forming laminate layers which are directly
bonded together without adhesives, with a valve containing layer
directly adhesivelessly bonded over the channel containing layers
and a flexible valve member integral with the valve layer to open
and close communication between feed and sensor channels of the
network.
[0014] U.S. Pat. No. 5,962,081, which issued Oct. 5, 1999 to
Pharmacia Biotech AB, describes a method for the manufacturer of
polymer membrane-containing microstructures such as valves by
combining polymer spin deposition methods with semiconductor
manufacturing techniques.
[0015] U.S. Pat. No. 5,977,355, which issued on Oct. 26, 1999 to
Xerox Corporation, describes a valve array system for microdevices
based on microelectro-mechanical systems (MEMS) technology
consisting of a dielectric material forming a laminate which is
embedded within multiple laminate layers.
[0016] U.S. Pat. No. 6,068,751, which issued on May 30, 2000,
describes a microfluidic delivery system using elongated
capillaries that are enclosed along one surface by a layer of
malleable material which is shifted by a valve having a
electrically-powered actuator.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of the present invention to
provide an efficient valve suitable for use in a microfluidic
system.
[0018] It is a further object of the present invention is to
provide a microfluidic valve which can be integrated into a
cartridge constructed of multi-layer laminates.
[0019] It is a further object of the present invention is to
provide an array of microfluidic valves which can be integrated
into a cartridge constructed of multi-layer laminates.
[0020] These and other objects of the present invention will be
more readily apparent in the description and drawings which
follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a perspective view of a microfluidic valve
according to the present invention;
[0022] FIG. 2 is a fragmentary cross-sectional view of an
alternative valve according to the present invention;
[0023] FIG. 3 is a fragmentary cross-sectional view of the valve of
FIG. 2 shown in its activated position;
[0024] FIG. 4 is a fragmentary top view, partly in phantom, of the
valve of FIG. 2;
[0025] FIG. 5 is a fragmentary cross-sectional view of another
alternative valve according to the present invention;
[0026] FIG. 6 is a fragmentary cross-sectional view of the valve of
FIG. 5 shown in its activated position;
[0027] and FIG. 7 is a perspective view of an array which uses
valves according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] A basic zero dead volume valve according to the present
invention is shown in FIG. 1. Referring now to FIG. 1, a valve
generally indicated at 10 consists of a membrane layer 12 which
covers a flat surface 13 coupled to an input channel 14, which is
connected to a flow channel 16 and also an output channel 18
connected to a flow channel 20. Above layer 12 is an air chamber 22
which is coupled to a pneumatic source 24 by a short air channel
26. In operation, zero dead volume valve 10 works as follows: a
liquid 30 enters channel 16 and travels into channel 14 where it
contacts membrane layer 12. Under atmospheric conditions within air
chamber 22, membrane lines flat against surface or seat 13, causing
liquid 30 to stop in channel 14. However, if the fluid pressure
within channel 14 exceeds the elastic force contained in membrane
13, membrane 13 will bulge out into chamber 22, allowing liquid 30
to pass under membrane 13 and flow out through channel 18 and into
channel 20, as shown by the arrows in FIG. 1. Valve 10 shown in
FIG. 1 may operate as a zero volume valve, as it is a normally
closed valve in which sufficient fluid pressure moves the membrane
away from its sealing position to open with only atmospheric
pressure within chamber 22.
[0029] When in operation within a microfluidic circuit, pneumatic
pressure within channel 24 is used to open and close valve 10. If
it is desirable to keep valve 10 in its closed position, positive
air pressure is applied through source 24 into channel 26, when it
fills air chamber 22, which forces membrane 12 against seat 13. It
has been found that applying +1.0 psi air pressure within source 24
will adequately keep valve 10 closed. It is desirable to open valve
10, a negative pressure of -55 mm Hg creates a vacuum within
chamber 22 to completely lift membrane 12 away from seat 13 to
allow liquid 30 to travel from channel 14 across surface 13 out of
channel 18. Pressure from source 24 can also be varied to vary the
flow through valve 10.
[0030] FIGS. 2-4 show an alternate embodiment in which a valve 40
is constructed as a normally open valve. Referring now to FIG. 2, a
latex rubber diaphragm membrane 50 is held between two spacing
layers 54 of a laminated microfluidic structure. Valve 40 is
fabricated from a series of laminar sheets 60 which are preferably
MYLAR.RTM. or a similar plastic sheet. Channels are constructed
within valve 40 by cutout spaces within spacing layers 54 between
sheets 60. In FIG. 2 is in its relaxed state, which allows liquid
to enter a flow inlet 62, and pass through a channel 64 into a
lower chamber 66 below membrane 50. The liquid can flow out of
valve 40 from chamber 66 through a channel 68 and out through a
flow outlet 70. Flow through valve 40 is controlled by pneumatic
pressure which is supplied by a valve air supply channel 72 through
a channel 74 into an upper chamber 76.
[0031] Operation of valve 40 is clearly shown in FIG. 3. Referring
now to FIG. 3, sufficient air pressure is supplied via channel 72
through channel 74 and into upper chamber 76. This pressure forces
membrane 50 to flex downwardly into lower chamber 66, blocking
channels 64 and 68, preventing fluid flow between inlet 62 and
outlet 70.
[0032] FIGS. 5 and 6 show another embodiment of the valve of the
present invention. Referring now to FIG. 5, which shows the normal
"on" state of the valve, a valve 80 is constructed from a pair of
laminar MYLAR.RTM. sheets 82 which are separated by a series of
spacing layers 84. Channels are formed in spacing layers 84 by
cutout sections which form a flow structure. A flexible membrane 86
is held between two spacing layers 84 in its relaxed state. A fluid
input channel 90 is connected to channel 92 and to an upper chamber
94. A fluid output chamber 96 is also coupled to upper chamber 94.
A pneumatic supply channel 98 is connected to a lower chamber 100.
In its normal inactivated state, valve 80 is "on," allowing liquid
to flow from inlet 90 to outlet 96. When it is desirable to turn
valve 80 "off," sufficient air pressure is supplied to supply
channel 98, filling lower chamber 100 with pressurized air and
forcing membrane 86 upwardly into upper chamber 94, sealing scaling
channel 92 such that the flow passage from inlet 90 to outlet 96 is
blocked, closing valve 80, as can be seen in FIG. 6.
[0033] FIG. 7 shows an array 110 in which a plurality of valves 80
can be constructed. Array 110 includes a plurality of input air
ports 112 along with a plurality of input fluid ports 114. Each of
valves 80 can be selectively operated to control fluid flow through
a microfluidic device. Such an array of microfluidic valves can be
integrated into a cartridge constructed of multi-layer laminates,
and can be used to control multiple parallel fluidic processes, or
a single process at multiple locations in a microfluidic circuit.
Such a system may have applications in drug discovery processes, or
in the analysis of multiple samples.
[0034] While the present invention has been shown and described in
terms of preferred embodiments thereof, it will be understood that
this invention is not limited to any particular embodiment and that
changes and modifications may be made without departing from the
true spirit and scope of the invention as defined in the appended
claims.
* * * * *