U.S. patent application number 10/746282 was filed with the patent office on 2005-07-07 for devices comprising multiple capillary inducing surfaces.
This patent application is currently assigned to Biosite, Inc.. Invention is credited to Buechler, Kenneth Francis.
Application Number | 20050147531 10/746282 |
Document ID | / |
Family ID | 25014818 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050147531 |
Kind Code |
A1 |
Buechler, Kenneth Francis |
July 7, 2005 |
Devices comprising multiple capillary inducing surfaces
Abstract
Assay device structures for a device where fluid flows from a
one region to another. The device structures comprising one or more
capillarity-inducing structures; where the capillarity-inducing
structure induces capillary force along an axis that is essentially
perpendicular to the axis along which capillary force induced in
another region of the device.
Inventors: |
Buechler, Kenneth Francis;
(Rancho Santa Fa, CA) |
Correspondence
Address: |
FOLEY & LARDNER
P.O. BOX 80278
SAN DIEGO
CA
92138-0278
US
|
Assignee: |
Biosite, Inc.
|
Family ID: |
25014818 |
Appl. No.: |
10/746282 |
Filed: |
December 24, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10746282 |
Dec 24, 2003 |
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09612815 |
Jul 10, 2000 |
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6669907 |
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09612815 |
Jul 10, 2000 |
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08749702 |
Nov 15, 1996 |
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6113855 |
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Current U.S.
Class: |
422/400 |
Current CPC
Class: |
B01L 3/50273 20130101;
B01L 2300/0825 20130101; B01L 2400/086 20130101; B01L 3/5023
20130101; B01L 3/502746 20130101; B01L 3/502707 20130101; B01L
2400/0406 20130101 |
Class at
Publication: |
422/058 |
International
Class: |
G01N 021/00 |
Claims
What is claimed is:
1. An assay device comprising a proximal region and a distal
region, wherein the proximal region comprises an effective
capillarity-induced along a first axis, and the distal region
comprises an effective capillarity-induced along a second axis,
where the minimum distance which the first axis and the second axis
are disposed relative to one another is between 40.degree. and
90.degree..
Description
RELATED PATENT APPLICATIONS
[0001] This application is a continuation of, and claims priority
from, U.S. patent application Ser. No. 09/612,815, filed on Jul.
10, 2000 and U.S. patent application Ser. No. 08/749,702, filed on
Nov. 15, 1996. The content of both applications are hereby
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This application concerns capillarity, also referred to as
capillary action or capillary force. In a particular embodiment,
the invention concerns an assay device that comprises multiple
capillary force-inducing surfaces having distinct positional
orientations.
BACKGROUND ART
[0003] With the advent of field-based testing and point of care
testing in hospitals, it has become increasingly important to
develop diagnostic products which are simple, rapid and convenient
for use. In these contexts, results are generally needed rapidly,
with a minimum of time given to the performance of a test.
Providing an assay result in minutes allows prompt action to be
taken in a hospital or field setting.
[0004] Field-based testing (i.e., a non-laboratory setting) has
become increasingly common. Such non-laboratory settings include,
e.g., environmental testing for contaminants, testing in
workplaces, and testing in sports medicine at an activity site.
Testing in non-laboratory settings may often be performed by
individuals who have minimal training in the conducting of assays,
or those who do not regularly conduct assays. Additionally,
non-laboratory settings often lack the same level of access to
assay equipment or reagents found in laboratories. Thus, it would
be advantageous to have an assay device for use in a non-laboratory
setting that is simple to use, and where the device does not
necessitate laboratory equipment beyond the assay device itself;
such devices are also advantageous in hospital/laboratory
settings.
[0005] Point of care and non-laboratory testing is facilitated by
compact small devices which are convenient to transport and use.
Preferably the design is easily manipulated by the individual
performing the assay. It is also preferable that the assay device
be capable of being fed into hand-held instrument that provides a
determination (qualitative or quantitative) of the assay result.
Devices capable of being fed into hand-held instruments (such as a
reader) are preferably compact and have a flattened
configuration.
[0006] Preferably a device for use in point of care or
non-laboratory settings does not require any additional equipment
to affect an assay. This feature makes the device easier to use and
avoids the need to purchase or use any additional equipment. For
example, it is preferred that such a device does not require
externally applied pressure.
[0007] Capillary force has been used to achieve movement in assay
devices without externally applied pressure. To achieve such
movement, e.g., assay material is placed in a proximal location in
the device, a location that contains a base level of capillary
force. One or more distal regions contain surfaces that induce
comparable or greater capillary force than the base level at the
proximal location. If more than one distal region contains surfaces
that induce capillary force, the effective amount of capillary
force induced is successively greater at each distal region, or is
comparable in all regions so that there is proximal to distal
movement of fluid through the device.
[0008] A problem with the use of capillarity as a means to achieve
proximal-to-distal movement through a device concerns the fluid
volume required to perform an assay, i.e., the "assay volume." An
assay result is often achieved only when the sample has traveled
through the device. In some cases, e.g., when bound label is used
as a means of detection of an analyte, an assay result is only
achieved when the unbound label is removed from the zone in which
the bound label is detected. Moreover, if multiple reactants must
be added to the device, the distal region of the device must
accommodate sufficient volume for the sample and all reactant
fluids. However, in order to achieve sufficient distal capillarity
in a compact device, dimensions in the distal areas are often
extremely minute. Moreover, minute dimensions are often desired in
assay devices to improve reaction kinetics, by minimizing diffusion
distances for the assay reagents.
[0009] If sample and non-sample fluids must be accommodated
distally, devices with sufficient capillarity and the requisite
capacity have highly impractical configurations for laboratory or
field settings. If a capillary in a distal region is made larger to
accommodate an assay volume (a reaction volume and other needed
volumes), the drop in capillarity in that region often impairs
fluid flow into the region.
[0010] Accordingly, there is a need for an efficient, compact,
economical device that permits the assay result to be readily
determined. It is also preferable that the device not necessitate
additional assay equipment in order for an assay to be
performed.
DESCRIPTION OF FIGURES
[0011] FIG. 1 is schematic depicting a top view of a device 10 in
accordance with the invention with lid 20 removed to permit
viewing; the fluid access port of lid 20 is shown in broken lines
in the location it would have with the lid in place.
[0012] FIG. 2 depicts a cross-section of FIG. 1 taken along plane
2-2 of FIG. 1; FIG. 2 depicts device 10 having lid 20 in place.
[0013] FIG. 3 depicts a cross-section of FIG. 1 taken along plane
3-3 of FIG. 1; FIG. 3 depicts device 10 having lid 20 in place.
[0014] FIG. 4 depicts a top view of distal region 16 of one
embodiment of the invention.
[0015] FIG. 5A-B depicts a capillarity inducing structure (Panel A)
and an array of said structures (Panel B) of a distal region of one
embodiment of the invention.
[0016] FIG. 6A-B depicts a capillarity inducing structure (Panel A)
and an array of said structures (Panel B) of a capillary region of
one embodiment of the invention.
[0017] FIG. 7A-B depicts top views of a capillarity inducing
structure (Panel A) and an array of said structures (Panel B) of a
capillary region of one embodiment of the invention.
[0018] FIG. 8A-B depicts top views of a capillarity inducing
structure (Panel A) and an array of said structures (Panel B) of a
capillary region of one embodiment of the invention.
[0019] FIG. 9A-B depicts top views of a capillarity inducing
structure (Panel A) and an array of said structures (Panel B) of a
capillary region of one embodiment of the invention.
DISCLOSURE OF THE INVENTION
[0020] Disclosed is a device comprising a "proximal" region and a
"distal" region, wherein the proximal region comprises an effective
capillary induced along a first axis, and the distal region
comprises an effective capillary induced along a second axis, where
the minimum distance which the first axis and the second axis are
disposed relative to one another is between 40.degree. and
90.degree.. The device can comprise one or more regions which
themselves comprise a capillarity-inducing structure; such
structures can be in a regular or irregular array. Each
capillarity-inducing structure of the array can be substantially
uniform. In one embodiment, a capillarity-inducing structure
comprises an essentially hexagonal configuration when viewed along
at least one plane.
[0021] Also disclosed is an assay device comprising a proximal
region and a distal region fluidly connected to the proximal
region, whereby fluid flows from the proximal region to the distal
region without application of an external force, and said distal
region comprises at least one capillarity-inducing structure. The
proximal region can comprises a lower effective capillarity than
the distal region, or the proximal region can comprise similar
capillarity relative to the distal region so that fluid will flow
between the proximal and distal regions. The distal region of this
embodiment can comprise an array of capillarity-inducing
structures; each structure of the array can be regularly spaced
relative to adjacent capillarity-inducing structures.
[0022] A capillarity-inducing structure can comprise an essentially
uniform configuration taken along any cross-sectional dimension, or
can have an irregular configuration in one or more dimensions. In
one embodiment, a distal region can comprise an essentially
regularly spaced array of essentially uniformly hexagonally shaped
capillarity-inducing structures, when viewed from a perspective
essentially perpendicular to a direction of capillary fluid flow
through the device.
[0023] It is understood that proximal and distal are used for
clarity, e.g., fluid can be added at a distal region of a device
such that it flows toward a proximal region of the device.
Capillarity inducing structures can be located in proximal or
distal regions.
List of Reference Numerals
[0024] 10. Device
[0025] 12. Fluid Addition Port
[0026] 14. Proximal Region
[0027] 16. Distal Region
[0028] 18. Air Escape Port
[0029] 20. Lid
[0030] 22. Base
[0031] 24. Lateral Wall of Proximal Region 14
[0032] 26. Inner Surface of Lid 20
[0033] 28. Bottom Surface of Base 22
[0034] 30. Capillarity-Inducing Structure
[0035] 32. Lateral Wall of Distal Region 16
[0036] 34. A distance between a capillarity-inducing structure 30
and a lateral surface of distal region 16.
[0037] 36. A distance between adjacent capillarity-inducing
structures 30.
Modes for Carrying out Invention
[0038] Disclosed herein for the first time in the art are assay
device structures that accomplish the objectives of permitting a
compact assay device configuration together with enhanced assay
volumes. When conducting an assay in laboratory or non-laboratory
settings, it is frequently desired that only a small amount of
sample to be assayed be provided, compact devices are well suited
to this aspect. Additionally, devices comprising microcapillaries
are generally preferred because they are readily manipulated and
they provide for enhanced reaction kinetics. It is advantageous for
the device to be approximately the size of a human hand. This size
facilitates manipulation of the device, making it easier for the
individual conducting the assay to place any assay reactants into
the device. Additionally, devices which are readily held in the
human hand are of a size that facilitates packing, shipping and
storage of the devices.
[0039] However, small devices have limited capacity, and this
capacity can be insufficient for a requisite reaction volume or
assay volume. The assay device structures disclosed herein achieve
fluid flow through an assay device; advantageously, this fluid flow
is accomplished by use of capillarity without a need to employ any
additional external force such as hydrostatic pressure. As
discussed in greater detail below, preferred device structures
comprise a capillary region of the device that permits compact
design configurations, while still achieving an effective capillary
force to result in fluid flow, while increasing the fluid capacity
of the device.
[0040] As appreciated by one of ordinary skill in the art, fluid
moves between regions of similar capillarity or moves from regions
of lower capillarity, to regions of higher capillarity. When small
sample volumes are utilized in a device that achieves fluid flow
pursuant to capillary action, especially minute distances are
required between opposing surfaces in order to achieve requisite
levels of capillary force.
[0041] Unless special design parameters are integrated into a
device where fluid flows by capillary action, fluid flow stops at a
point where it reaches and fills the region having the highest
level of capillary force. As an example of a special design
structure which permits fluid flow past a region of higher
capillarity into a region of lower capillarity (see e.g., U.S. Pat.
No. 5,458,852, to Buechler, issued Oct. 17, 1995; and copending
U.S. application Ser. No. 08/447,895, which are incorporated by
reference herein).
[0042] If a capillary tube of generally cylindrical cross-section
is utilized to achieve capillarity at a distal region, there are
numerous disadvantages; typically, this would require an assay
device having an elongated configuration. If the end result of the
assay is determined from fluid located at the distal-most end of
the device it can be difficult to obtain an accurate reading from
material contained in the narrow and elongated capillary tube in
this region. Furthermore, the devices must contain a minimum assay
volume in order to produce an assay result. A capillary tube distal
region would need to be exceptionally long to accommodate the
reaction volume while still inducing the necessary capillary force,
effectively precluding a shape that is either hand held or readily
manipulated by an individual conducting an assay.
[0043] In practice, designing capillary spaces in assay devices
requires that several considerations be taken into account. First,
there is a reaction volume which interacts with various reagents,
this is generally the volume of sample required to achieve a
significant signal above background. A capillary in a device must
generally accommodate this volume. Second, if the assay requires
separation of bound from unbound signal generator or label (such as
would be required for a competitive, non-competitive or nucleic
acid hybridization assays on solid phases) then a wash volume of
fluid is required to wash away the unbound signal generator or
label from the detection area in a device. Generally, the wash
volume is approximately 0.5 to 10-times the reaction volume. A
capillary in an assay device must often accommodate a wash volume.
Third, when an assay requires binding of reactants to a solid
phases the capillary space should be as small as possible to
improve the kinetics of the reaction. Surface bound reactants can
include, for example, a solid phase bound antibody which reacts
with sample antigen, a solid phase bound antigen that reacts with
an antibody, or a surface bound nucleic acid that hybridizes to
another nucleic acid. Capillary spaces on the order of 0.5 .mu.m to
200 .mu.m are useful for these binding reactions. Fourth, when the
reaction and wash volumes are defined, then the total volume that
the device is required to hold is calculated; this volume is
referred to as the assay volume. When the assay volume that a
device requires is greater than the actual volume that the device
holds, then the device capillaries must be made larger to
accommodate the volume, this offsets the kinetic advantages from
microcapillaries of a small device.
[0044] The present invention is particularly useful in compact
devices (having rapid reaction kinetics) where the device volume
would otherwise be insufficient to accommodate the assay volume.
Pursuant to the present invention, one can design a device where
fluid moves by capillary force, where the device comprises a given
force-inducing capillary space, concomitantly increasing the
capacity of the device. The capacity is increased without
decreasing the capillarity of the device, and without increasing
the size of the device.
[0045] In accordance with the present invention, assay device
surfaces are provided whereby the opposing surfaces which induce
capillary force distally have a different positional orientation
relative to more proximal capillarity-inducing surfaces.
[0046] For convenience herein, the following terms will be utilized
in describing an embodiment of the invention, it is understood that
this terminology is in no way limiting on the invention. A compact
assay device having a flattened configuration will be discussed.
This device has a proximal region to which sample fluid is added.
Distal to the proximal region are one or more regions that have
similar or higher capillarity than the sample addition region. FIG.
1 depicts a top view of an assay device; regions of the device are
not drawn to scale. As shown in FIG. 1, device 10 contains fluid
addition port 12. A proximal region 14 is fluidly connected to
addition port 12. A distal region 16 is fluidly connected to
proximal region 14. Contiguous with distal region 16 is an escape
port 18, to permit fluids such as gas to escape, allowing fluid
flow through the device and into region 16.
[0047] FIG. 2 depicts a cross-section of device 10 taken along line
2-2 in FIG. 1. As seen in FIG. 2, a lid 20 and base 22 serve to
define a cross-sectional area of proximal region 14. In a typical
design configuration, the distance between lateral walls 24 is
appreciably greater than the distance between the inner surface 26
of lid 20 and bottom surface 28 of base 22; this configuration
permits fluid flow through the device to be readily viewed by an
individual conducting the assay by looking through a device
embodiment comprising a transparent or translucent lid 20. Again
referring to FIG. 2, it is seen that the surfaces creating the
greatest amount of capillary force in proximal region 14 are inner
surface 26 of lid 20 and bottom surface 28 of lid 22. For
convenience, herein surface 26 is referred to as an upper surface,
and bottom surface 28 is referred to as a lower surface. In the
context of the figures, the capillarity force is said to be along
the "X" axis, or in a horizontal direction.
[0048] If one attempted to use a design configuration analogous to
that of proximal region 14 in distal region 16 such that region 16
could contain the assay volume, it would require the upper surface
and the lower surface to be exceedingly close to one another, and
the distal region would need to continue for an impractically long
distance. Alternatively, the distal region would require an
exceptionally wide distance between lateral walls defining the
space. If one attempted to balance the length and width at the
distal region to provide a squared configuration, it is then very
difficult to manufacture surfaces that are a uniform distance apart
throughout the entire region. These design problems are exacerbated
when producing a design where the distal region accommodates an
appreciable assay volume.
[0049] To overcome such design limitations, the preferred
embodiment of the invention comprises a distal region such as
depicted in FIG. 3. FIG. 3 is a cross-section of an embodiment
taken along line 3-3 in FIG. 1. For purposes of illustration, FIG.
3 is not drawn to scale.
[0050] As shown in FIG. 3, in a preferred embodiment, one or more
capillarity-inducing structures 30 are provided in a device in
accordance with the invention, most preferably an array of such
structures are provided.
[0051] Again referring to FIG. 3, capillarity-inducing structures
are configured so that the distance between two or more lateral
surfaces (e.g., the minimum distance between a lateral wall 32 of
distal region 16 and capillarity inducing structure 30 or between
two adjacent capillary inducing structures 30) is approximately the
same or less than the distance between lower surface 26 of lid 20
and upper surface 28 of base 22. When this configuration is
utilized, the distance between the lower surface of the lid and the
upper surface of the base can be increased in the region comprising
capillarity-inducing structures, thereby enlarging the capacity of
the region.
[0052] In accordance with the design as depicted in FIG. 1, FIG. 2,
and FIG. 3, it is seen that the proximal region comprises
capillarity induced by the distance between inner surface 26 of lid
20 and bottom surface 28 of base 22. As depicted in these figures,
the capillarity is induced in a vertical direction. In contrast,
the capillarity-inducing surfaces in distal region 16 are lateral
surfaces; capillary force is induced in a horizontal direction. The
direction of capillary force in the distal region is referred to as
the "X" axis relative to the "Y" axis of capillarity force in the
proximal region.
[0053] An advantageous aspect of the present invention is that,
since the capillarity in the distal region is induced in a
horizontal direction by lateral surfaces, that the relative spacing
of the upper and lower surfaces do not significantly impact
capillarity in the region. Accordingly, the upper and lower
surfaces can be spaced apart so as to permit a compact device
having closely spaced surfaces to accommodate any necessary assay
volume. Thus, devices are provided that provide good reaction
kinetics, are compact, and which readily accommodate assay volumes
not otherwise permitted in devices of such configuration.
[0054] It is understood that in order to achieve fluid flow from
proximal region 14 to distal region 16, the effective capillary
force of distal region 16 must be similar to or greater than that
of proximal region 14. As appreciated by one of ordinary skill in
the art in view of the disclosure herein, a sufficient number of
capillarity-inducing structures 30 are provided in distal region 16
to achieve the requisite effective capillarity in the distal
region. Although it is possible for the distance between two
adjacent lateral surfaces in the distal region to be greater than
the distance between an upper and lower surface in that region, the
effective capillary force for the distal region must be similar to
or greater than that for the proximal region so that fluid will
flow between these two regions. Typically, an array of
capillarity-inducing structures are utilized, where the effective
capillarity of the region is induced by lateral surfaces of
adjacent capillarity inducing structures. Preferably,
capillary-inducing structures have a uniform shape and are spaced
in a regular pattern.
[0055] FIG. 4 depicts a top view of distal region 16 of one
embodiment of the invention. As seen in FIG. 4, there is a distance
34 between a capillarity-inducing structure 30 and lateral wall 32
of distal region 16, this distance is greater than the distance
between inner surface 26 of lid 20 and bottom surface 28 of base 22
in proximal or distal regions (not depicted in this view). For this
embodiment, proximal region 14 had a capillary force induced by the
distance between the opposing surfaces 26 and 28. Nevertheless, the
effective capillary force of distal region 16 is greater than
proximal region 14 in the device due to the array of
capillarity-inducing structures provided. In this embodiment, the
effective capillarity is induced by a distance 36 between adjacent
capillary-inducing structures, rather than by a distance between
the lid and the base.
[0056] In the embodiment depicted in FIG. 4, capillarity-inducing
structures 30 have a hexagonal configuration in top view and these
structures are placed in a regular array in part or all of the
distal region. It is understood that other top-view configurations
are also possible, such as geometric or organic shapes. Further,
although a regular array of capillarity-inducing structures is
preferred, a random array is also encompassed within the invention,
so long as distal region 16 comprises an effective capillary force
produced in accordance with the principles of the invention. Each
hexagonal structure preferably has six essentially planar sides
when viewed 360.degree. full circle from a perspective such as that
in FIG. 4.
[0057] Preferably, capillarity-inducing structures 30 have a
regular configuration when viewed in cross-section, such as seen in
FIG. 3 or FIG. 4. It is understood, however, that
capillarity-inducing structures can comprise irregular
configurations when viewed from a perspective such as in FIG. 3 or
FIG. 4.
[0058] As disclosed herein, it is seen that the effective
capillarity in proximal region 14 is less than the effective
capillarity in distal region 16, or the relative capillarities are
similar such that fluid will flow between these regions. In
proximal region 14, capillary force is induced between upper and
lower surfaces, i.e., along the vertical or "Y" axis. The capillary
force in distal region 16 is induced by lateral surfaces with
capillary force being induced in the horizontal or along the "X"
axis. For example, capillarity in region 16 is induced by the
distance between lateral wall 32 of base 16 and
capillarity-inducing structure 30 and/or between adjacent
capillarity-inducing structures (distance 36). In accordance with
the invention, capillarity-inducing structures can be placed in
proximal or in distal regions.
EXAMPLES
[0059] Several embodiments have been constructed which exemplify
the principles of the present invention. In accordance with these
examples, it is shown that fluid flowed between two regions; for
each example, flow was seen to occur in a proximal-to-distal as
well as a distal-to-proximal direction.
[0060] For the following embodiments of devices comprising two or
more capillary regions in fluid connection, the following capillary
regions were utilized:
[0061] The capillary region depicted in FIG. 5 comprised an array
of hexagonal structures. When seen from a top view, each structure
had a form of a hexagon circumscribed around a circle of 75 microns
in diameter, as depicted in FIG. 5A. As shown in FIG. 5B, the array
of structures constituted a regular placement of structures in
linear rows in a proximal to distal direction. Each structure in a
given linear row was positioned 170 microns from the position of
each adjacent structure in that row. Each linear row was staggered
(proximal-distal) relative to each adjacent linear row by a
distance of 85 microns. Each adjacent linear row was laterally
displaced 75 microns relative to each adjacent row. The distance
between two parallel sides of adjacent structures was 36.1 microns
in this embodiment.
[0062] In the embodiment of FIG. 5, the distance between the lid
and the base of this region was 12 microns; this was the distance
believed to induce the capillarity in this region. For the
embodiment depicted in FIG. 5, each structure was 10 microns high.
The 2 micron distance between the top of a hexagonal structure and
the lid merely filled with liquid, then ceased to impact the
effective capillarity of the region. The hexagonal structures
served to decrease the surface tension of a fluid flow front,
whereby the fluid flow front was essentially perpendicular to
lateral walls.
[0063] The region depicted in FIG. 6 comprised an array of
structures. When seen from a top view, each structure had a form of
a hexagon circumscribed around a circle of 45 microns in diameter,
as depicted in FIG. 6A. As shown in FIG. 6B, the array of
structures constituted a regular placement of structures in linear
rows in a proximal to distal direction. Each structure in a given
linear row was positioned 120 microns from the position of each
adjacent structure in that row. Each linear row was staggered
(proximal-distal) relative to each adjacent linear row by a
distance of 60 microns. Each linear row was laterally displaced
72.5 microns relative to each adjacent row. The distance between
two parallel sides of adjacent structures was 43.2 microns in this
embodiment.
[0064] In the embodiment of FIG. 6, the distance between the lid
and the base of this region was 12 microns; this was the distance
believed to induce the effective capillarity of this region. Each
hexagonal structure for the embodiment depicted in FIG. 6 was 10
microns high. The 2 micron distance between the top of a hexagonal
structure and the lid merely filled with liquid, then ceased to
impact the effective capillarity of the region. The hexagonal
structures served to decrease the surface tension of a fluid flow
front, whereby the fluid flow front was essentially perpendicular
to lateral walls.
[0065] The region depicted in FIG. 7 comprised an array of
structures. When seen from a top view, each structure had a form of
a hexagon circumscribed around a circle of 100 microns in diameter,
as depicted in FIG. 7A. As shown in FIG. 7B, the array of
structures constituted a regular placement of structures in linear
rows in a proximal to distal direction. Each structure in a given
linear row was positioned a distance of 190 microns from the
position of each adjacent structure in that row. Each linear row
was staggered relative to each adjacent linear row by a distance of
95 microns. Each linear row was laterally displaced
(proximal-distal) 87.5 microns relative to each adjacent row. The
distance between two parallel sides of adjacent structures was 26
microns in this embodiment.
[0066] In the embodiment of FIG. 7, the distance between the lid
and the base of this region was 12 microns; this was the distance
believed to induce the effective capillarity of this region. Each
structure in the embodiment depicted in FIG. 7 was 10 microns high.
The 2 micron distance between the top of a hexagonal structure and
the lid merely filled with liquid, then ceased to impact the
effective capillarity of the region. The hexagonal structures
served to decrease the surface tension of a fluid flow front,
whereby the fluid flow front was essentially perpendicular to
lateral walls.
[0067] The capillary region depicted in FIG. 8 comprised an array
of capillarity-inducing structures. When seen from a top view, each
capillarity-inducing structure had a form of a hexagon
circumscribed around a circle of 10 microns in diameter, as
depicted in FIG. 8A. As shown in FIG. 8B, the array of
capillarity-inducing structures constituted a regular placement of
capillarity-inducing structures in linear rows in a proximal to
distal direction. Each capillarity-inducing structure in a given
linear row was positioned a distance of 35 microns from the
position of each adjacent capillarity-inducing structure in that
row. Each adjacent linear row was staggered relative to each
adjacent linear row by a distance of 17.5 microns. Each adjacent
linear row was laterally displaced 10 microns relative to each
adjacent row. The distance between two parallel sides of adjacent
capillarity-inducing structures was 10.2 microns in this
embodiment; this was the distance believed to induce the effective
capillarity of this region. For the embodiment depicted in FIG. 8,
each capillarity-inducing structure was 20 microns high. The
distance between the lid and the base in this region was 22
microns. The 2 micron distance between the top of a
capillarity-inducing structure and the lid merely filled with
liquid, then ceased to impact the effective capillarity of the
region.
[0068] The capillary region depicted in FIG. 9 comprised an array
of capillarity-inducing structures. When seen from a top view, each
capillarity-inducing structure had a form of a hexagon
circumscribed around a circle of 10 microns in diameter, as
depicted in FIG. 9A. As shown in FIG. 9B, the array of
capillarity-inducing structures constituted a regular placement of
capillarity-inducing structures in linear rows in a proximal to
distal direction. Each capillarity-inducing structure in a given
linear row was positioned a distance of 38 microns from the
position of each adjacent capillarity-inducing structure in that
row. Each linear row was staggered relative to each adjacent linear
row by a distance of 19 microns. Each linear row was laterally
displaced 11 microns relative to each adjacent row. The distance
between two parallel sides of adjacent capillarity-inducing
structures was 12 microns in this embodiment; this was the distance
believed to induce the effective capillarity of this region. For
the embodiment depicted in FIG. 9, each capillarity-inducing
structure was 20 microns high. The distance between the lid and the
base in this region was 22 microns. The 2 micron distance between
the top of a capillarity-inducing structure and the lid merely
filled with liquid, then ceased to impact the effective capillarity
of the region.
Example 1
[0069] In this embodiment, fluid was found to flow between a
proximal region comprising an array of structures as depicted in
FIG. 7B, and a distal region comprising an array of
capillarity-inducing structures such as depicted in FIG. 8B. The
effective capillarity of the proximal region was believed to be
induced by the 12 micron distance from the inner surface of the lid
to the upper surface of the base, i.e., capillary force induced in
a "vertical" direction. The effective capillarity of the distal
region was believed to be induced by the 10.2 micron distance
between parallel walls of adjacent capillarity-inducing structures,
i.e., capillary force induced in a "horizontal" direction.
[0070] The proximal region comprised a height of 12 microns from
the inner surface of the lid to the upper surface of the base; the
height of the distal region was 22 microns from the inner surface
of the lid to the upper surface of the base. Accordingly, the
distal region had a greater capacity than the proximal region for a
given area defined from the top view.
Example 2
[0071] In this embodiment, fluid was found to flow between a
proximal region comprising an array of structures such as found in
FIG. 6B, and a distal region comprising an array of
capillarity-inducing structures such as depicted in FIG. 9B.
[0072] The effective capillarity of the proximal region was
believed to be induced by the 12 micron distance from the inner
surface of the lid to the upper surface of the base, i.e.,
capillary force induced in a "vertical" direction. The effective
capillarity of the distal region was believed to be induced by the
12 micron distance between parallel walls of adjacent
capillarity-inducing structures, i.e., capillary force induced in a
"horizontal" direction.
[0073] The proximal region comprised a height of 12 microns from
the inner surface of the lid to the upper surface of the base; the
height of the distal region was 22 microns from the inner surface
of the lid to the upper surface of the base. Accordingly, the
distal region had a greater capacity than the proximal region for a
given area defined from the top view.
Example 3
[0074] In this embodiment, fluid was found to flow between a
proximal region comprising an array of structures such as depicted
in FIG. 5B, and a distal region comprising an array of
capillarity-inducing structures such as depicted in FIG. 8B.
[0075] The effective capillarity of the proximal region was
believed to be induced by the 12 micron distance from the inner
surface of the lid to the upper surface of the base, i.e.,
capillary force induced in a "vertical" direction. The effective
capillarity of the distal region was believed to be induced by the
10.2 micron distance between parallel walls of adjacent
capillarity-inducing structures, i.e., capillary force induced in a
"horizontal" direction.
[0076] In this embodiment, the height of the first distal region
was 12 microns from the inner surface of the lid to the upper
surface of the base; the height in the distal region was 22 microns
from the inner surface of the lid to the upper surface of the base.
Accordingly, the distal region had a greater capacity than the
proximal region for a given area defined from the top view.
[0077] Closing
[0078] Although the device has been described with reference to the
embodiments depicted in the Figures, it is understood that the
invention is not limited in any way by a particular embodiment. For
example, base 10 need not itself comprise any portions which
delimit lateral surfaces of either proximal region 14 or distal
region 16. Lateral surfaces can be provided by a separate component
discrete from lid 20 or base 22, or be provided by some component
of lid 20.
[0079] The invention also encompasses a series of one or more
proximal and/or one or more distal regions all in fluid connection.
For example, where fluid flows sequentially between two or more
regions comprising capillarity-inducing structures as well as
flowing through a proximal region.
[0080] Although the terms horizontal, vertical, upper, lower, and
lateral have been used herein, it is understood that these terms
were provided to facilitate description of the invention as
depicted in the Figures. It is also understood the relative
orientations would change as a device is moved. Furthermore, the
terms X-axis and Y-axis have been used; these terms are intended to
designate relative linear orientations that are substantially
disposed-perpendicular to one another. By "substantially disposed
perpendicular" to one another it is intended that the X and Y axes
are disposed a minimum of between 40.degree. and 90.degree.
relative to each other. Moreover, the orientation of the proximal
and distal locations in the device can be reversed, such that the
fluid addition zone is at the distal end, and fluid flows in a
distal to proximal direction.
[0081] It must be noted that as used herein and in the appended
claims, the singular forms "a," "and," and "the" include plural
referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a formulation" includes mixtures of
different formulations and reference to "the method of treatment"
includes reference to equivalent steps and methods known to those
skilled in the art, and so forth.
[0082] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar to equivalent to those described
herein can be used in the practice or testing of the invention, the
preferred methods and materials are now described. All publications
mentioned herein are incorporated herein by reference to describe
and disclose specific information for which the reference was cited
in connection with.
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