U.S. patent application number 10/215354 was filed with the patent office on 2003-01-30 for indicator components for microfluidic systems.
This patent application is currently assigned to Caliper Technologies Corp.. Invention is credited to Berndt, Manfred, Kaltenbach, Patrick, Kennedy, Colin B., Unno, Garrett.
Application Number | 20030021725 10/215354 |
Document ID | / |
Family ID | 23490115 |
Filed Date | 2003-01-30 |
United States Patent
Application |
20030021725 |
Kind Code |
A1 |
Unno, Garrett ; et
al. |
January 30, 2003 |
Indicator components for microfluidic systems
Abstract
Microfluidic devices and systems that include keying,
registration or indication elements that communicate a
functionality of the microfluidic device to the instrumentation
which is used in conjunction with these devices. Indicator elements
include structural indicators, electrical indicators, optical
indicators and chemical indicators. Different indicator elements
are indicative of different functionalities, e.g., applications,
new vs. used, and the like.
Inventors: |
Unno, Garrett; (San Jose,
CA) ; Kennedy, Colin B.; (Mill Valley, CA) ;
Kaltenbach, Patrick; (Bischweier, DE) ; Berndt,
Manfred; (Waldbronn, DE) |
Correspondence
Address: |
CALIPER TECHNOLOGIES CORP
605 FAIRCHILD DRIVE
MOUNTAIN VIEW
CA
94043
US
|
Assignee: |
Caliper Technologies Corp.
605 Fairchild Drive
Mountain View
CA
94043
|
Family ID: |
23490115 |
Appl. No.: |
10/215354 |
Filed: |
August 8, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10215354 |
Aug 8, 2002 |
|
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09377681 |
Aug 19, 1999 |
|
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|
6495104 |
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Current U.S.
Class: |
422/50 ; 204/601;
204/650; 422/400 |
Current CPC
Class: |
B01L 3/5027 20130101;
B01L 2300/0816 20130101; B01L 9/527 20130101; B01L 2200/027
20130101; G01N 2035/00237 20130101; B01L 2400/0487 20130101; B01L
2400/0415 20130101; B01L 2200/143 20130101; B01L 2200/025 20130101;
B01L 3/502715 20130101; B01L 3/545 20130101; B01L 2300/021
20130101 |
Class at
Publication: |
422/50 ; 422/99;
204/650; 204/601 |
International
Class: |
G01N 037/00; G01N
027/26 |
Claims
What is claimed is:
1. A microfluidic device, comprising: a body structure configured
to interface with a base instrument, the body structure having
microfluidic elements disposed therein; and an indicator element
fabricated into the body structure, the indicator element providing
an indication to an instrument of a functionality of the
microfluidic device.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 09/377,681 filed Aug. 19, 1999, the disclosure
of which is incorporated herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] Microfluidic devices and systems have advanced rapidly from
academic postulations to functioning commercial research products
that are actively contributing to the research and development of
pharmaceutical and other biotechnological and chemical
products.
[0003] Examples of microfluidic devices and systems for performing
a variety of different operations are described in, e.g., WO
98/00231, WO 98/05424, WO 98/22811, WO 98/46438 and WO 98/49548,
all of which are incorporated herein by reference in their entirety
for all purposes. Such microfluidic systems are generally
configurable to perform virtually any operation, assay or
experiment previously performed at the laboratory bench, but with a
greater degree of accuracy, speed and automatability. Specifically,
because microfluidic systems are performed in such small spaces,
reagent quantities, an mixing times are substantially reduced.
Further, because of the integrated nature of microfluidic systems,
e.g., channel networks fabricated in a single chip, multiple
different operations can be incorporated into a single device and
controlled by an automated control and detection system. The
availability of automated instrumentation, in turn, provides for
unparalleled reproducibility as compared to bench scale operations,
which rely upon measurements and judgements of human operators.
[0004] It is generally desirable to be able to automate more and
more operations that are to be performed within a laboratory. While
microfluidic systems, in general, contribute substantially to this
automation desire, there exits a number of other operations that
can be automated in conjunction with the use of these devices. The
present invention provides apparatuses systems and methods that
further contribute to this automation trend.
SUMMARY OF THE INVENTION
[0005] In a first aspect, the present invention provides a
microfluidic device comprising a body structure configured to
interface with a base instrument. The body structure includes
microfluidic elements and an indicator element fabricated into the
body structure. The indicator element provides an indication to an
instrument of a functionality of the microfluidic device.
[0006] Another aspect of the present invention is a microfluidic
system comprising a controller instrument. The controller
instrument is comprised of a microfluidic device nesting region
having an interface array for operably coupling one or more of a
material transport system and a detector disposed within the
controller instrument with a microfluidic device placed in the
nesting region. The system also includes a microfluidic device
having a body structure. The body structure includes an indicator
element. The indicator element provides an indication to the
instrument of a functionality of the microfluidic device.
BRIEF DESCRIPTION OF THE FIGURES
[0007] FIG. 1 schematically illustrates an overall microfluidic
analysis system.
[0008] FIG. 2 schematically illustrates a microfluidic device.
[0009] FIG. 3 schematically illustrates the device registration
elements of the present invention. FIG. 3A shows a microfluidic
device that includes a number of different registration elements as
described herein. FIG. 3B shows a view of a portion of the overall
instrument including the interface portion that includes the device
corral with one example of registration elements. FIG. 3C is an
exploded view of the nesting region of an instrument similar to
that shown in FIG. 3B, showing the registration elements.
[0010] FIG. 4 is an alternate schematic illustration of a
microfluidic device and accompanying instrument that comprise
mechanical indicator elements/registration structures.
[0011] FIG. 5 schematically illustrates one example of a
microfluidic device incorporating an electrical indicator element
according to the present invention.
[0012] FIG. 6 schematically illustrates a microfluidic device
including an optical indicator element and accompanying
instrument.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention permits greater automatability by
configuring the device to communicate one or more functionalities
of the microfluidic device to instrumentation, and particularly
controlling and/or detection instrumentation, to facilitate the
operation of the combination of the device and instrumentation.
[0014] As used herein, a "functionality" of a microfluidic device
refers to the use to which the device will be or has been put. The
indicated functionality of a device may range from the relatively
general, e.g., for performing multi-sample separations, to more
specific, e.g., performing kinetic assay on a protein kinase
sample. Thus, as typically used, the functionality refers to the
application for the device. However, the term "functionality" as
used herein, also includes whether a device is functional for any
application in the first instance, e.g., whether the device is
nonfunctional as a previously used device.
[0015] Typically, from application to application, microfluidic
devices and systems rely upon many of the same means to carry out
the desired operation, e.g., in fluid or material movement, mixing
etc., as well as detection of operation results. As such,
instrumentation for operating these systems is generally
standardizable, with the devices themselves, the chemistries placed
in those devices, and the timing of reagent mixtures yielding
distinctions between different operations.
[0016] For these standard instruments, different operating
parameters, e.g., for performing different operations must
generally be preprogrammed into the instrument or computers that
control operation of the instruments. Of course it is still
incumbent upon the user to identify for the instrument when a
different application is to be performed. In accordance with the
present invention, however, a microfluidic device is configured
with an indicator element which indicates to the instrument the
functionality of the device that is interfaced with the instrument,
e.g., the specific type of assay or other application that is to be
performed, or whether the device has been previously used. The
instrument then typically adjusts for carrying out the operation of
the device interfaced with it. For example, the instrument may
select from different available detection modes, e.g., fluorescence
wavelengths, UV transmittance, etc., as well as different available
material transport means, e.g., pressure based fluid transport,
electrokinetic transport or hybrid pressure/electrokinetic systems.
For specifically identified functionalities, e.g., specific
separations, enzyme assay or the like, the instrument also
optionally implements control profiles, e.g., a script for
directing fluids or other materials through specific channels at
specific times and/or in specific ratios, volumes and/or flow
rates.
[0017] An overall system including a microfluidic device and its
associated instrumentation is illustrated in FIG. 1. As shown, the
system includes a microfluidic device 100, which is selected from a
menu of devices having different functionalities, e.g., devices
100-106. As described in greater detail below, the microfluidic
device typically includes an indicator element to communicate to
the instrumentation of the system the functionality of that device.
The system also typically includes a controller detector instrument
108, upon or into which the device is placed for operating the
device. Once mounted on the instrument, detector 110 is disposed
adjacent to the device 100 and within sensory communication of the
channels disposed in the device, in order to detect results of
reactions within those channels. As used herein "within sensory
communication" refers to a detector that is positioned to receive a
signal from a channel of the microfluidic device, typically at a
detection window. Such signals include optical signals, thermal
signals, electrical signals, and the like. In each case, the
detector is placed such that the detection aspect of the detector,
e.g., a sensor, is placed so as to receive the appropriate type of
signal from the channel. In the case of optical signals, the
detector is typically placed adjacent to a transparent region of
the channel with the optical elements positioned to receive an
optical signal and detect that signal. In the case of electrical
detectors, a sensor is typically disposed within the channel in
order to be within sensory communication.
[0018] Controller 120, also disposed in the instrument 108,
controls the movement of materials through the channels and/or
chambers of the microfluidic device in order to carry out the
device's prescribed functionality. A computer or processor 130 is
also typically provided to instruct the operation of the controller
120 in response to user input or programmed commands. The computer
130 also typically receives data from the detector 110, stores
and/or analyzes the data to provide information to the user in a
readily understandable format. Although illustrated as a separate
element, it will be appreciated that the computer or processor 130
may be integrated into the instrument 108 as well.
[0019] As used herein, a "microfluidic device" refers to a device
that includes at least one fluidic element, e.g., channel, chamber,
reservoir or the like, that has at least one cross sectional
dimension in the microscale range, e.g., between about 0.1 and
about 1000 .mu.m. Typically, such devices include networks of
channels and/or chambers that are interconnected, and through which
a variety of different fluids or other materials are transported.
These devices are used to mix, separate, react and otherwise
manipulate sample reagents and other materials in performing a
variety of chemical, biochemical and biological analyses.
Microfluidic devices may be fabricated in a variety of different
ways. For example, a device may be fabricated as an aggregation of
different parts, e.g., capillaries, reaction chambers, etc., that
are pieced together to form a desired network of channels and/or
chambers. In preferred aspects however, microfluidic devices are
assembled from an aggregation of planar layers to form a single
integrated microfluidic device that includes the channels and
chambers within its interior portion.
[0020] One example of a microfluidic device is illustrated in FIG.
2. Specifically, FIG. 2 illustrates the layered construction of
preferred microfluidic devices. As shown, the device body structure
200 is fabricated from two or more layers 202 and 208. In
particular, the bottom portion of the device 202 comprises a solid
substrate that is substantially planar in structure, and which has
at least one substantially flat upper surface 204. The channels
and/or chambers of the microfluidic devices are typically
fabricated into the upper surface of the bottom substrate or
portion 202, as microscale grooves or indentations 206, using the
above described microfabrication techniques. The top portion or
substrate 208 also comprises a first planar surface 210, and a
second surface 212 opposite the first planar surface 210. In the
microfluidic devices prepared in accordance with the methods
described herein, the top portion also includes a plurality of
apertures, holes or ports 214 disposed therethrough, e.g., from the
first planar surface 210 to the second surface 212 opposite the
first planar surface.
[0021] The first planar surface 210 of the top substrate 208 is
then mated, e.g., placed into contact with, and bonded to the
planar surface 204 of the bottom substrate 202, covering and
sealing the grooves and/or indentations 206 in the surface of the
bottom substrate, to form the channels and/or chambers (i.e., the
interior portion) of the device at the interface of these two
components. The holes 204 in the top portion of the device are
oriented such that they are in communication with at least one of
the channels and/or chambers formed in the interior portion of the
device from the grooves or indentations in the bottom substrate. In
the completed device, these holes function as reservoirs for
facilitating fluid or material introduction into the channels or
chambers of the interior portion of the device, as well as
providing ports at which electrodes may be placed into contact with
fluids within the device, allowing application of electric fields
along the channels of the device to control and direct fluid
transport within the device.
[0022] These devices may be used in a variety of applications,
including, e.g., the performance of high throughput screening
assays in drug discovery, immunoassays, diagnostics, genetic
analysis, and the like, e.g., as described in Published
International Patent Application No. 98/00231 and U.S. Pat. No.
5,779,868 each of which is hereby incorporated by reference in its
entirety for all purposes.
[0023] Indicator elements fabricated or otherwise disposed within a
microfluidic device may take on a variety of forms, including
mechanical indicator elements, electrical indicator elements,
optical indicator elements and chemical indicator elements. The
specific type of indicator element used in a particular device is
mirrored by a complementary detection element upon the instrument
which is interfaced with the device.
[0024] Mechanical indicator elements typically comprise a
registration structure or collection of registration structures or
structural elements fabricated onto, into or attached to the body
of the microfluidic device. The registration structures on the
device mate with or otherwise engage elements upon the nesting
region of an instrument. The elements upon the instrument may
include complementary registration structures which are configured
only to receive the registration structures of a particular device,
e.g., having a specific application. In such cases, only one type
of device will be permitted to interface with the nesting region or
adapter element of the instrument, as other devices will not
possess the same complementary registration elements or structures.
In order to interface a different device with the instrument, one
is required to swap out the adapter element/nesting region for an
adapter having the appropriate registration structures. The use of
interchangeable adapter elements for interfacing different
microfluidic devices to a common instrument platform has been
previously described in, e.g., published International Patent
Application No. WO 98/05424, which is incorporated herein by
reference in its entirety for all purposes.
[0025] A variety of registration or indicator structures are
optionally employed in this aspect of the present invention. For
example, a series of pins, posts, blocks, tabs, etc. may be
disposed upon the surface of the nesting region of the instrument.
A corresponding and complementary series of holes, depressions,
notches, cavities are then disposed on the device to receive the
structures on the instrument when the microfluidic device is
appropriately oriented on the nesting region. Although described as
positive structures, e.g., protrusions, being disposed on the
instrument and negative structures, e.g., depressions, being
disposed on the microfluidic device, it will be appreciated that
the complementary structures may be disposed upon either the device
or the instrument.
[0026] Alternatively or additionally, the microfluidic device may
incorporate at least one shaped edge, e.g., having a unique
contour, that is complementary to an edge of the nesting region,
such that absent the appropriately shaped edge, the microfluidic
device will not be insertable into the nesting region of the
instrument.
[0027] FIG. 3 schematically illustrates an example of a
registration/indicator structure on a microfluidic device and its
controller/detector instrument. FIG. 3A illustrates the
microfluidic device 300 that includes a number of exemplary
registration structures, from a number of views (top, side, end and
perspective). As shown, the device 300 includes a body structure
302 which includes a microfluidic substrate attached or integral
thereto (not shown). The body structure includes ports or
reservoirs 304 disposed thereon which are in fluid communication
with the channel elements of the microfluidic device. The body
structure of the device also includes a number of registration
structures, e.g., notch 306 and truncated corner 308, which provide
an indication of the functionality of the microfluidic device,
e.g., the particular application for which the device is used,
i.e., nucleic acid separations, protein separations, enzyme assays,
cellular function assays and the like. Specifically, the position,
number and or size of the registration structures is typically
varied from a device of one functionality to a device of another
functionality. For example, although illustrated with a single
notch 306 along one edge of the body structure 302, multiple
notches, or different size notches are optionally used along the
same edge or different edges of the body structure to identify the
functionality of the overall device.
[0028] A complementary structure or set of structures on the
instrument is used to ensure that the instrument is appropriately
configured to interface, control and monitor the functionality,
e.g., the application, of the microfluidic device inserted therein.
FIG. 3B illustrates a portion of an example of a controller
detector instrument 320 that includes a nesting region 322 onto
which the device 300 is mounted.
[0029] A lid 324 is rotatably attached to the instrument 320. The
underside of the lid 326 typically includes a number of interface
elements for controlling the functioning of the device. For
example, as shown, a plurality of electrodes 328 are provided
attached to the underside 326 of the lid 324. These electrodes 328
rotate into communication with fluids in the reservoirs 304 in the
body structure of device 300. These electrodes 328 that are
operably coupled to power sources (not shown) within the instrument
320, provide actuation of material movement within the channels of
the device 300 via electrokinetic forces. Although shown as
electrodes 328, other interfaces are optionally or additionally
provided in the lid. For example, in certain preferred aspects, one
or more vacuum or pressure ports are provided in the lid with
appropriate connectors for interfacing with one or more reservoirs
304 of the device 300, in order to provide material movement by
pressure induced flow. These vacuum or pressure ports are operably
coupled to vacuum or pressure pumps disposed within the instrument
320. As shown, at least a portion of the lid 324 is removable and
replaceable, in order to reconfigure the instrument to interface
with a wide range of different devices. In particular, interface
cassette 324a, which includes the array of electrodes 328, is
removable from lid 324, and a different cassette may be inserted in
its place. This three-tier instrument architecture (e.g., device,
instrument and removable interface adapter) is described in detail
in Published International Patent Application No. WO 98/05424,
which is incorporated herein by reference.
[0030] FIG. 3C shows an exploded view of a nesting region shown in
FIG. 3B, absent a microfluidic device. As shown, the nesting region
322 includes a microfluidic device "corral" 330 which functions to
both orient the device 300 upon the nesting region, and ensure that
the instrument 320 is appropriately configured for the
functionality of the device 300. Orientation of the device is
provided, inter alia, by a number of structures on the nesting
region, including barrier 332, alignment pins 334, and barrier 336.
The presence of these orientation structures ensures that a device
300 placed into the nesting region 322 is appropriately positioned
such that the collection lens 338 of a detector disposed in the
instrument (not shown) is placed adjacent to and in sensory
communication with a relevant channel of the microfluidic device
300. Proper orientation is also desirable to provide for proper
interfacing of other elements of the instrument with the
microfluidic device, e.g., heating element or heat sink 340, and
flow actuation elements in the lid 324, e.g., electrodes 328.
[0031] As shown, barrier 336 includes additional structural
elements that are used to both align the device 300 in the nesting
region 322, as well as provide an indication of the functionality
of the device 300 to be used, e.g., which the instrument is
configured to run at a particular given time. In particular, the
interior edge 338 of barrier 336 defines one boundary of corral 330
against which a microfluidic device is positioned. As shown, a
first tab 348 is provided extending into the corral 330. The tab
348 is positioned and sized to fit within the notch 306 that is
disposed along the edge of the microfluidic device 300. The
interior edge 338 of barrier 336 also defines a truncated corner
342 that corresponds and is complementary to the truncated corner
308 of device 300. As shown, barrier 336 also includes structural
registration elements that communicate the functionality of the
device to the instrument. In particular, posts 344 and 346 are
disposed on barrier 336. These posts are positioned and sized
(e.g., diameter, height etc.) to indicate the particular
functionality of the microfluidic device to which they are applied.
As shown, post 344 is thinner and taller than post 346. With
reference to FIG. 3B, these posts 344 and 346 are positioned to
mate with corresponding apertures or cavities 344a and 346a,
respectively, in interface cassette 324a or optionally lid 324. The
complementary nature of posts 344, 346 and cavities 344a and 346a,
ensures that the interface cassette 324a inserted into lid 324 is
appropriate for the particular device 300, as indicated by the
registration structures on barrier 336, e.g., notch 306, and posts
344 and 346. In preferred aspects, a portion or all of barrier 336
is removable (e.g., barrier portion 336a), allowing for
substitution with a barrier that includes different registration
elements, e.g., numbers and sizes of notches, posts and the like.
In operation, microfluidic devices having different functionalities
include different registration structures on their body structure,
which registration structures are indicative of the functionality
of the device. When a device having a different functionality is to
be run on an instrument, one replaces the barrier 336 with a new
barrier having registration structures complementary to the
functionally desired device, and also substitutes the interface
cassette with an appropriate interface for the new device, e.g.,
electrode configuration, vacuum or pressure ports, etc. Certain of
the registration structures on the cassette 324a and barrier 336
cooperate to ensure that both the cassette and the barrier are
appropriate for the device to be run. Improper cooperation of these
elements can lead to damaging of elements of the device and/or the
interface cassette, e.g., bending electrodes, damaging optics, etc.
Proper alignment of the microfluidic device in the nesting region
is shown in FIG. 3D.
[0032] Thus, in accordance with the above-described aspect of the
present invention, "indication of a device's functionality to the
instrument" is provided by an ability to close lid 324 over the
device 300, e.g., improper interfacing of a device and an
instrument is prevented by structural interference of one or more
of the registration elements, e.g., as between device 300 and
barrier 336 and/or between barrier 336 and interface cassette 324a.
Thus, this "indication" encompasses both more active communication
between the device and the instrument, as described in greater
detail herein, as well as passive communication, e.g., as described
with reference to FIG. 3.
[0033] FIG. 4 schematically illustrates alternate examples of a
microfluidic device having mechanical indicator or registration
elements, as described herein. As shown, a microfluidic device body
structure 400 (shown from a side view), is provided having a series
of notches 404-412 disposed in its lower surface 402. The
arrangement, size and shape of these notches 404-412 is selected
depending upon the particular application or functionality of the
microfluidic device. For example, as shown, the body structure
includes narrow notches 404, 406 and 410 and wider notches 408 and
412. The notches 404-412 on the body structure 400 correspond and
are generally complementary to registration structures disposed
upon the nesting region 452 of a controller/detector instrument
(not shown). As shown, these registration structures include, e.g.,
posts 454-462, which are provided in a position and of a size such
that when the body structure is placed upon the nesting region, the
notches 404-412 engage or receive the posts in a fitted fashion,
securing the body structure in position, e.g., as shown in Panel A.
Further, interaction among these two elements is only generally
possible where these structures are complementary. As a result, the
functionality of the microfluidic device, e.g., as indicated by the
indicator structures, is communicated to the instrument through the
inclusion of a proper nesting region 452, e.g., in an appropriate
adapter element.
[0034] Optionally, the elements on the instrument that are engaged
by the registration elements comprise displaceable elements that
are displaced by the registration structures on the device (or are
not displaced where the registration structure comprises a notch,
slot, groove or cavity). Specifically, such elements typically
comprise pins, tabs or other structures within the nesting region
of the device, that are spring mounted such that they are normally
extended into the nesting region of the device, but whereby
presence of the device in the nesting region displaces some or all
of these elements. Typically, these displaceable elements are also
operably coupled to the control or processor elements of the
instrument, whereby displacement of an element is detected by the
instrument, e.g., through the completion or breaking of an
electrical circuit within the instrument. The identity and number
of the plurality of these displaceable elements that is displaced
by the registration structures of a particular device serves as an
identification code for that device. In this manner, the
registration structures on the device function as a key which,
based upon the identity and number of elements displaced, indicates
to the instrument, the functionality of the microfluidic
device.
[0035] This alternative aspect is shown in Panel B of FIG. 4.
Specifically, the registration structures on the nesting region 452
comprise an array of movable or displaceable elements, e.g., posts
464-498, which are deflectable upon interaction with the indicator
structures on the body structure 400. For example, as shown, the
nesting region 450 includes an array of deflectable posts 464-498
extending into the nesting region. When a device's body structure
400 is placed onto the nesting region, the indicator structures on
the body 400, e.g., notches 404-412 deflect the posts in a pattern
reflective of those indicator structures, e.g., only posts 66,
72-76, 82-86 and 90-92 are deflected. The deflection or lack of
deflection of each post is detected by the instrument. As a result,
the functionality of the device, as indicated by the arrangement,
size and position of notches (or other indicator structures), is
communicated to the instrument by virtue of the number and identity
of the posts that are deflected by the body of the device. In this
latter aspect, the "indication" of a device's functionality is more
of an active communication between the device and the instrument,
e.g., by virtue of the device's active deflection of certain
structures ("switches") on the instrument. The instrument then
configures itself, e.g., via software or firmware programming, to
run the device mounted thereon.
[0036] In alternate aspects, the indicator elements fabricated into
or otherwise disposed on or within the microfluidic devices,
comprise electrical indicator elements. The electrical indicator
elements described herein may be passive or active electrical
elements. In preferred aspects, the electrical indicators are
passive, e.g., having no internal power supply such as a battery,
due to the costs associated with such systems. While not preferred,
it will be appreciated that active electrical indicator elements
are also envisioned within the scope of the present invention.
[0037] Typically, electrical indicator elements comprise one or
more electrical circuits disposed on or within the body of the
microfluidic device. The electrical circuits are typically oriented
to contact two or more electrical contacts disposed upon the
nesting region of the controller instrument, so as to complete an
electrical circuit between the two or more contacts. The indicator
function of the electrical indicator elements is optionally
provided by the number and identity of different circuits that are
completed when the device is inserted into the nesting region.
Specifically, the pattern of electrical circuits connects a
distinct set or subset of electrical contacts in the nesting region
to yield an electrical signature that is indicative of the
functionality of the device used. Alternatively, the specific
resistance or conductivity of the electrical circuits on the device
is varied among different devices, such that this resistance level
comprises the electrical signature that is indicative of the
functionality of the device.
[0038] Fabrication of electrical circuits into or on a device's
body may be accomplished by a number of means. For example, in some
aspects, simple patterned metal layers are disposed upon an outer
surface of the body so as to contact a preselected subset of
electrical contacts disposed upon the nesting region, thereby
yielding a preselected electrical signature when a current is
applied to the electrical contacts. Alternatively, integrated
circuits may be attached to or disposed within the body structure
of the device. Such integrated circuits generally permit a greater
complexity of available electrical signatures using combinations of
specific circuits and relative resistances to provide the
signature.
[0039] In certain aspects, an electrical indicator element may
provide an indication to the instrument as to whether the
microfluidic device has been previously used or the nature of any
previous use. As a result of a previously used device, an
instrument may refuse to operate, or it may prompt the user as to
the desirability of using a previously used device. In a preferred
aspect, this type of electrical indicator element comprises one or
more electrical circuits, e.g., as described above, except that one
or more of the circuits functions as a modifiable fused link. In
operation, following the use of the device, the instrument sends a
programmed electrical surge or other signal through the circuit or
circuits of interest, resulting in modification of the fused link
and of the electrical circuit. For example, such fused links may be
severable via the electrical signal, resulting in severance of the
electrical circuit. In multi-use devices, several such links may be
provided, each being severed after a subsequent use, until the
recommended number of uses has been carried out. Alternatively,
such fuses may be simply modified via the electrical signal, e.g.,
having an altered electrical signal, e.g., resistance or the
like.
[0040] One example of an electrical indicator element is
illustrated in FIG. 5. As shown, a microfluidic device 500 is
provided attached to the bottom surface 504 of a holder assembly
502 (see U.S. Pat. No. 6,251,343) which doubles as an overall body
structure. The reservoirs 506-528 of the device 500 communicate via
ports 530-552 to the upper surface of the holder assembly 504. As
shown, the holder assembly 502 includes an array of electrical
contact pads 554-564. These contact pads are positioned to contact
a similar set of contact pads in the nesting region of a
controller/detector instrument (not sown).
[0041] Upon the body structure/holder assembly 502, electrical
circuits, e.g., circuits 566 and 568, are provided connecting
different pairs or sets of the electrical contact pads 554-564. As
shown, these circuits 566 and 568 comprise metal patterns that are
fabricated onto the bottom surface 504 of the holder assembly 502.
When inserted into the nesting region, the instrument, via its
electrical contact pads, applies a low level current through the
electrical circuits 566 and 568, on the holder assembly 502. The
specific pattern of the electrical circuits is identified by the
instrument, e.g., by virtue of the presence or absence of current
between two separate contact pads, the level of resistance of those
circuits, or both. By way of example, in the device shown in FIG.
5, an electric current could be applied between contact pads 554
and 558, e.g., via circuit/wire 566, and between pads 562 and 564,
via circuit/wire 568. However no other currents could be applied or
detected due to the lack of an existing circuit. Additionally or
alternatively, the electrical resistance in the existing circuits
is optionally varied as an indicator function. This increases the
variability of the signaling function.
[0042] As noted above, one or more of the electrical circuits,
e.g., wires 566 and 568 comprises a fused link. Such fused links
are generally provided such that a known level of electrical
current will excessively heat the wire, resulting in its melting
and severing. These circuit compositions are well known to those of
skill in the electronics arts.
[0043] Although illustrated as an array of contact pads connected
by wires or metal traces, it will be appreciated that in preferred
aspects, an integrated circuit is used to provide the electrical
circuits on the body of the device. Specifically, the complexity of
circuits available through IC technology allows substantially
greater variability in an electrical indicator element. Further,
such ICs are readily incorporated into the body of the devices of
the invention, e.g., in the same fashion the microfluidic device
substrate is attached to the holder assembly 502 in FIG. 5.
Electrical interaction with the nesting region is then accomplished
in the same fashion as shown in FIG. 5, or alternatively, through
the inclusion of electrical connector pins, i.e., as typically used
in the electronics industry for connecting ICs to circuit
boards.
[0044] In a further aspect, the indicator element fabricated into
or otherwise disposed on the body of the microfluidic device
comprises an optical indicator element. As used herein, an optical
indicator element is an element that is optically detected by the
instrument. Again, as with the electrical indicator elements
described above, optical elements may be passive or active, e.g.,
emitting detectable light levels. Typically, however, passive
optical indicators are preferred. One example of a particularly
preferred type of optical indicator element is a bar code that is
affixed to or otherwise attached or fabricated onto the
microfluidic device's body structure. Specifically, bar codes may
be readily employed as indicators of the particular assay or other
functionality of the microfluidic device being used. Instruments
used in conjunction with those devices that incorporate include
detection systems for detecting the optical indicator elements. In
the case of bar codes, suitable and well known bar code readers are
incorporated into the instrument and oriented to read the device's
bar code from the body of a device inserted into the nesting region
of the instrument.
[0045] An example of a device incorporating an optical indicator
element is schematically illustrated in FIG. 6. As shown in panel
A, the device 600 includes a bar code 602 disposed on an upper
surface 604 of the device 600. As shown in panel B, when the device
600 is inserted into the nesting region 652 of an instrument 650, a
detector 654 for optically detecting the bar code 602 is placed
adjacent to the bar code 602. The detector 604 scans and detects
the bar code and relays the information embodied within the code to
the instrument 650, indicating the functionality of the device 600
to the instrument 650.
[0046] Examples of chemical indicator elements include reservoirs,
wells or the like incorporating detectable chemicals, e.g., fluids
having predefined ionic strengths, pH, and the like, which are
indicative of a functionality of the device itself.
[0047] All publications and patent applications are herein
incorporated by reference to the same extent as if each individual
publication or patent application was specifically and individually
indicated to be incorporated by reference. Although the present
invention has been described in some detail by way of illustration
and example for purposes of clarity and understanding, it will be
apparent that certain changes and modifications may be practiced
within the scope of the appended claims.
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