U.S. patent application number 09/888754 was filed with the patent office on 2002-01-24 for feedback control for microfluidic cartridges.
Invention is credited to Hayenga, Jon W..
Application Number | 20020008032 09/888754 |
Document ID | / |
Family ID | 22796813 |
Filed Date | 2002-01-24 |
United States Patent
Application |
20020008032 |
Kind Code |
A1 |
Hayenga, Jon W. |
January 24, 2002 |
Feedback control for microfluidic cartridges
Abstract
A device for sensing fluid movement within a microfluidic
channel which uses feedback to control its operation. The device
measures electric parameters to interpret fluidic parameters such
as flow speed, and the presence or absence of fluid within the
channel.
Inventors: |
Hayenga, Jon W.; (Redmond,
WA) |
Correspondence
Address: |
JERROLD J. LITZINGER
SENTRON MEDICAL, INC.
4445 LAKE FOREST DR.
SUITE 600
CINCINNATI
OH
45242
US
|
Family ID: |
22796813 |
Appl. No.: |
09/888754 |
Filed: |
June 25, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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60213865 |
Jun 23, 2000 |
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Current U.S.
Class: |
204/603 ;
137/455; 204/451; 204/452; 204/601; 422/400; 422/67 |
Current CPC
Class: |
G01N 2035/00237
20130101; G01N 2035/00544 20130101; B01L 2400/0406 20130101; B01L
2400/0409 20130101; F16K 99/0023 20130101; B01L 2400/0655 20130101;
F16K 99/0059 20130101; Y10T 137/7722 20150401; B01L 3/502738
20130101; B01L 2400/043 20130101; F16K 99/0001 20130101; B01L
3/502715 20130101; B01L 2300/0822 20130101; B01L 2400/0688
20130101; F16K 2099/0084 20130101; B01L 3/5025 20130101; G01N 27/06
20130101; B01L 3/5027 20130101; B01F 25/433 20220101; B01L
2400/0415 20130101; F15C 3/06 20130101; B01L 2300/0887 20130101;
F16K 99/0015 20130101; B01F 31/441 20220101; B01F 33/3039 20220101;
F16K 99/0011 20130101; B01L 2200/10 20130101; B01L 2300/0636
20130101; B01L 2400/0403 20130101; B01L 2400/0457 20130101; F16K
99/0042 20130101; B01F 25/4331 20220101; B01L 2200/0636 20130101;
F16K 99/0046 20130101; F15C 3/04 20130101; B01L 2300/0867 20130101;
B01F 33/30 20220101; F16K 99/0017 20130101; F16K 2099/008 20130101;
G01N 35/0098 20130101; F16K 99/0013 20130101; B01F 33/451 20220101;
B01L 3/5023 20130101 |
Class at
Publication: |
204/603 ;
204/451; 204/452; 204/601; 422/67; 422/100; 137/455 |
International
Class: |
F16K 031/00; G01N
027/26; G01N 027/447 |
Claims
What is claimed is:
1. A microfluidic device, comprising: a microfluidic channel having
an inlet and an outlet; means associated with said channel and
located between said inlet and said outlet, for sensing fluid flow
within said channel, and generating electrical signals
corresponding to fluidic properties of the fluid flow; and means,
coupled to said sensing means, for controlling fluid flow through
said channel as a result of information obtained from said
electrical signals from said sensing means.
2. The device of claim 1, wherein said sensing means comprises an
electrode assembly.
3. The device of claim 2, wherein said electrode assembly includes
a plurality of electrodes.
4. The device of claim 1, wherein said sensing means is positioned
within said microfluidic channel.
5. The device of claim 1, wherein said control means further
comprises: means for analyzing said electrical signals from said
sensing means, and means for pumping a fluid into the inlet of said
microfluidic channel in response to commands from said analyzing
means.
6. The device of claim 1, wherein said sensing means comprises an
optical detector.
7. The device of claim 1, wherein said optical detector is located
in close proximity to said microfluidic channel.
8. The device of claim 7, wherein said optical detector comprises a
light source located on one side of said channel and a light
detector located on the other side of said channel such that the
light from said source may be altered by the presence or absence of
a liquid in said channel.
9. The device of claim 1, wherein said sensing means is capable of
detecting wetout in said channel.
10. The device of claim 1, wherein said sensing means is capable of
detecting the presence of a liquid within said channel.
11. The device of claim 1, wherein said sensing means is capable of
detecting the presence of a gas within said channel.
12. The device of claim 2, wherein said electrode assembly is
located within said channel and is capable of detecting the flow
speed of fluids flowing within said channel.
13. The device of claim 5, wherein said pumping means is capable of
changing the flow rate of a fluid within said channel in response
to a command from said analyzing means.
14. The device of claim 1, wherein said sensing means is capable of
detecting a meniscus of a liquid flowing within said microfluidic
channel.
15. The device of claim 1, wherein said sensing means comprises a
hot wire anemometer.
16. The device of claim 5, wherein said pumping means is capable of
stopping a fluid from flowing within said channel in response to a
signal from said analyzing means.
17. The device of claim 5, wherein said analyzing means includes a
computer link.
18. The device of claim 1, wherein said fluidic properties include
conductivity.
19. The device of claim 1, wherein said fluidic properties include
capacity.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application claims benefit from U.S. Provisional
Patent Application Serial No. 60/213,865, filed Jun. 23, 2000,
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 microfluidic
cartridge which uses embedded electrodes for feedback control in
the operation of its device.
[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] The use of electrodes within microfluidic channels for the
manipulation of fluids has been practiced extensively in the prior
art. U.S. Pat. No. 5,126,022 teaches a device for moving molecules
by the application of a plurality of electrical fields by the use
of a plurality of electrodes which were placed at regular intervals
along a gel-filled channel which produced traveling electrical
waves propelling charged particles through the medium within the
channel for separation and resolution purposes.
[0008] U.S. Pat. No. 5,989,402 teaches an electrically controlled
microfluidic system having an electrical interfere array with a
plurality of electrode pins which are oriented for insertion into a
plurality of ports. The electrode pins on each electrically coupled
to a separate electrical lead, which leads are connected to an
electrical control system which concomitantly delivers a voltage to
each of the leads.
[0009] U.S. Pat. No. 6,007,690 is directed to a device for
performing microchannel electrophoresis in capillaries, in which
the main electrophoretic flow path has associated with it at least
one pair of electrodes for applying an electric field to the medium
present in the flow path, thus providing for precise movement of
entities along the flow path.
[0010] U.S. Pat. No. 6,171,850 is directed to a device for
performing temperature controlled reactions and analyzes in
microfluidic systems. Heat exchangers are fabricated from a
material that is both thermally and electrically conductive, so
that they can function as both a heat exchanger and an electrode
when placed into a fluid filled reservoir.
SUMMARY OF THE INVENTION
[0011] It is therefore an object of the present invention to
provide a device which uses feedback from a sensing means to
control operation of a microfluidic device.
[0012] It is a further object of the present invention to provide a
device which measures electric parameters to determine the presence
or absence of fluid in microfluidic channels.
[0013] It is a still further object of the present invention to
provide a device which uses electrodes within microfluidic channels
to measure flow speed and wetout.
[0014] It is still a further object of the present invention to
provide a device which uses optical sensors located in proximity to
microfluidic channels to measure wetout.
[0015] These and other objects of the present invention will be
more readily apparent in the description and drawings that
follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a representation of a flow sensor according to the
present invention used within a microfluidic channel;
[0017] FIG. 2 is an enlarged view of the sensor and sensor holder
of the flow assembly shown in FIG. 1;
[0018] FIG. 3 is an exploded view of the sensor carrier device
shown in FIG. 1;
[0019] FIG. 4 is an assembled view of the device shown in FIG. 3;
and
[0020] FIG. 5 is a plan view of an optical sensor assembly
according the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Referring now to FIG. 1, there is shown a fluid sensor
assembly, generally indicated at 10, according to the present
invention. Assembly 10 uses a fluid sensor 12, which is located
within a microfluidic channel 14 to monitor the flow of fluids
within channel 14. Fluid is provided to channel 14 via a fluid
driving and control means 16. Means 16, which may contain a
separate fluid supply or merely pump fluid from another circuit
into channel 14, is coupled to channel 14 at a channel inlet 18.
The opposite end of channel 14 comprises a channel outlet 20, which
end may be coupled into additional microfluidic circuitry.
[0022] Sensor 12 is electrically coupled to driving and control
means 16 by a cable 22. Cable 22 provides electrical signals from
sensor 12 to means 16 relative to fluid flow within channel 14 at
the location where sensor 12 is positioned. These signals from
sensor 12 may be used by means 16 to measure specific electric
parameters, such as conductivity or capacity across channel 14. In
addition, these electric parameters can be used to interpret
fluidic parameters, such as flow speed, or the presence or absence
of fluid within channel 14.
[0023] Means 16 is capable of analyzing signals received from
sensor 12, and adapting the flow within channel 14 in response to
information received from sensor 12 via cable 22. This use of
feedback signals to control the operation of assembly 10 may be
implemented by a computer, programmable controller, or any other
device well known to persons familiar with this art.
[0024] Fluid flow within channel 14 may be in the form of a liquid
or a gas, and sensor 12 may be located at any point within channel
14, or may consist of multiple sensors located at different regions
of channel 14. Means 16 may detect a gradient between different
regions of channel 14 and react to the differences, such as
differences in flow speed or conductivity. As means 16 analyzes the
information returned from sensor 12, it reacts to adjust the
operation of fluid driving within channel 14.
[0025] Sensor 12 may consist of a single electrode, a series of
electrodes, an optical sensing device, or even a hot wire
anemometer capable of monitoring temperature changes within the
fluid flowing within channel 14. Many sensing devices capable of
performing these operations are well known in the art.
[0026] FIG. 2 illustrates an embodiment of the sensor and sensor
holder which may be used in conjunction with the present invention.
A sensor 30 is shown having a pair of electrodes 32, 34 embedded
within the body of sensor 30. Sensor 30 is adapted to be inserted
into an opening 36 within a sensor holder 38. Opening 36 is sized
such that sensor 30 slides into said opening from the rear and is
prevented from sliding out of the top by extensions 38a of holder
38.
[0027] FIG. 3 is an exploded view of a sensor for use in the
present invention. Sensor carrier device, generally indicated at
50, consists of an upper layer 52, a central layer 54, and a bottom
layer 56. Upper layer 52 includes a plurality of apertures 60, 62,
64. Aperture 64 allows sensor 30 to monitor conditions within a
microfluidic channel in which carrier device 50 is mounted, while
apertures 62, 64 provide access for the cabling to operate fluid
sensor assembly 10. Layer 54 includes a cutout section 66 for
accommodating sensor 30 within carrier device 50, while bottom
layer 56 is used to hold sensor 30 in its proper position for
operation. The assembled sensor carrier device 50 can be seen in
FIG. 4.
[0028] FIG. 5 illustrates the use of an optical sensor to determine
the wetout of a microfluidic channel. Light source 70 is positioned
in optical proximity to channel 71 such that it illuminates a
portion of channel 71. As channel 71 is filled, meniscus 72 creates
an optically detectable signal (e.g., absorption or light
scattering), which is picked up by detector 73. The detector signal
is then fed back through leads 74 into fluid driver 75 to control
the flow.
[0029] While the present invention has been shown and described in
terms of several preferred embodiments thereof, it will be
understood that this invention is not limited to these particular
embodiments and that many changes and modifications may be made
without departing from the true spirit and scope of the invention
as defined in the appended claims.
* * * * *