U.S. patent application number 10/689776 was filed with the patent office on 2004-03-25 for method and apparatus for liquid transfer.
Invention is credited to Caren, Michael P., Fisher, William D., Tella, Richard P..
Application Number | 20040058452 10/689776 |
Document ID | / |
Family ID | 22673538 |
Filed Date | 2004-03-25 |
United States Patent
Application |
20040058452 |
Kind Code |
A1 |
Fisher, William D. ; et
al. |
March 25, 2004 |
Method and apparatus for liquid transfer
Abstract
Liquids are transferred from a plurality of wells or depots
having openings arranged in a selected format to one or more
receptacles, by displacing liquid contained in each well so that a
convex meniscus swells from the opening, and contacting the
receptacle with the swollen meniscus to draw a portion of the
liquid into the receptacle. An apparatus for carrying out the
method includes a depot member having a plurality of wells having
openings supported in a selected format, and a receiving member
defining at least one receptacle and usually a plurality of
receptacles in a corresponding or complementary format; means for
displacing liquid contained within the wells toward and through the
openings; and means for bringing at least one selected well opening
into proximity with at least one selected receptacle.
Inventors: |
Fisher, William D.; (San
Jose, CA) ; Tella, Richard P.; (Sunnyvale, CA)
; Caren, Michael P.; (Palo Alto, CA) |
Correspondence
Address: |
AGILENT TECHNOLOGIES, INC.
Intellectual Property Administration
Legal Department, DL429
P.O. Box 7599
Loveland
CO
80537-0599
US
|
Family ID: |
22673538 |
Appl. No.: |
10/689776 |
Filed: |
October 20, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10689776 |
Oct 20, 2003 |
|
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09183604 |
Oct 30, 1998 |
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Current U.S.
Class: |
436/180 ;
422/400 |
Current CPC
Class: |
Y10T 436/2575 20150115;
B01L 2400/0481 20130101; B01J 2219/00317 20130101; B01L 3/0262
20130101; C40B 60/14 20130101; B01J 2219/00387 20130101; B01J
2219/00585 20130101; G01N 35/1074 20130101; B01L 3/021 20130101;
B01J 2219/00659 20130101; B01J 2219/00605 20130101; B01J 2219/00369
20130101 |
Class at
Publication: |
436/180 ;
422/100 |
International
Class: |
G01N 001/10 |
Claims
We claim:
1. A method for transferring liquids from a plurality of wells
having openings arranged in a selected format to at least one
receptacle, comprising displacing liquid in each well so that a
convex meniscus swells from the opening, and contacting an orifice
of a receptacle with the swollen meniscus to draw at least a
portion of the liquid into the receptacle.
2. The method of claim 1, for transferring the liquids to a
plurality of receptacles arranged in a format corresponding to the
format of the well openings, comprising steps of displacing the
liquid contained in each well so that a convex meniscus swells from
the opening, and contacting the corresponding orifices of the
receptacles with the swollen menisci to draw a portion at least of
the liquids into the receptacles.
3. The method of claim 1 wherein the liquid displacing step
comprises inwardly deforming a wall of each well to displace the
liquid.
4. The method of claim 3 wherein the inwardly deforming step
comprises applying mechanical pressure at an outer surface of the
wall.
5. The method of claim 3 wherein the inwardly deforming step
comprises applying fluid pressure at an outer surface the wall.
6. The method of claim 1 wherein the step of displacing the liquid
comprises introducing a displacing fluid into a part of each well
away from the opening.
7. The method of claim 6 wherein the displacing fluid is introduced
through a vent through a part of the wall away from the
opening.
8. The method of claim 6 wherein the displacing fluid is passed
through a membrane covering the opening, the membrane being
permeable to the displacing fluid.
9. The method of claim 6 wherein the displacing fluid comprises a
gas.
10. The method of claim 1 wherein: the openings of the wells are in
a plate; the orifices are in a plate; and the two plates are
parallel during the contacting.
11. The method of claim 1 wherein the receptacle is part of a print
head such that the liquid is propelled through the orifice during
printing.
12. The method of claim 11 wherein the print head carries a
plurality of receptacles having respective orifices through which
liquid is propelled during printing.
13. The method of claim 11 wherein a plurality of swollen menisci
are aligned and contacted with a plurality of orifices at the same
time so that liquids may be transferred from a plurality of wells
to the plurality of orifices at the same time.
14. The apparatus of claim 12 wherein the print head comprises
means associated with each orifice for propelling liquid through
the associated orifice.
15. The apparatus of claim 13 wherein the propelling means
comprises a source of heat.
16. The apparatus of claim 13 wherein the propelling means
comprises a piezoelectric device.
17. A method according to claim 1 additionally comprising
propelling the liquid through the orifice.
18. A method according to claim 16 wherein liquid is propelled
through the orifices so as to fabricate an array of binding
agents.
19. A method according to claim 18 wherein the binding agents
comprise nucleic acids.
20. A method according to claim 18 wherein the binding agents
comprise peptides.
21. Apparatus for transferring a plurality of liquids, comprising a
depot member having a plurality of wells each having a first end
and an opening at a second end; a receiving member supporting at
least one receptacle having an orifice; means for displacing liquid
contained within the wells from the first end toward and through
the openings at the second end; and means for moving the well
openings and the at least one receptacle into proximity such that
liquid displaced through the well openings contacts the receptacle
at the orifice.
22. Apparatus of claim 21 wherein said receiving member supports a
plurality of receptacles, and the moving means moves a plurality of
the well openings and a plurality of the receptacles into
proximity.
23. The apparatus of claim 22 wherein the receiving member is
planar, and wherein the well openings are supported in a planar
format.
24. The apparatus of claim 21 wherein each well includes a
deformable wall portion at the first end, and the liquid-displacing
means comprise means for inwardly deforming the deformable wall
portions.
25. The apparatus of claim 24 wherein the wall-deforming means
comprises mechanical means for pressing at an outer surface of the
deformable wall portion.
26. The apparatus of claim 24 wherein the wall-deforming means
comprises means for applying fluid pressure at the outer surface of
the deformable wall portion.
27. The apparatus of claim 21 wherein each well comprises a vent
positioned away from the opening, and the liquid-displacing means
comprise means for introducing a displacing fluid through the vents
and into the wells.
28. Apparatus for transferring a plurality of liquids, comprising a
depot member having a plurality of wells each having a first end
and an opening at a second end; a receiving member supporting at
least one receptacle having an orifice; means for displacing liquid
contained within the wells from the first end toward and through
the openings at the second end; and means for moving the well
openings and the at least one receptacle into proximity such that
liquid displaced through the well openings contacts the receptacle
at the orifice; wherein each well comprises a vent positioned away
from the opening, and the liquid-displacing means comprise means
for introducing a displacing fluid through the vents and into the
wells; wherein the vent is covered by a membrane that is permeable
to the displacing fluid.
29. A depot member comprising a plate with a plurality of wells
each having a first end and an opening at a second end, wherein
each well includes a deformable wall portion at the first end, such
that when the deformable wall portion of each well is inwardly
deformed while water is in the well the water will be displaced
from the well to form a convex meniscus swelling from the
opening.
30. A depot member comprising a plate with a plurality of wells
each having an opening and a vent positioned away from the opening
wherein the vent is covered by a membrane that is permeable to a
displacing fluid, such that when displacing fluid is introduced
through the membrane and vent while water is in the well the water
will be displaced from the well to form a convex meniscus swelling
from the opening.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of allowed U.S. patent
application Ser. No. 09/183,604, originally filed Oct. 30, 1998 (on
which a CPA was filed) under the same title, and from which
priority is claimed and which is incorporated herein by
reference.
BACKGROUND
[0002] This invention relates to transferring liquids from one
container to another, and more particularly the invention relates
to methods and apparatus for transferring small quantities of
liquids from a multiplicity of depots to a multiplicity of
receptacles.
[0003] Continuing rapid advances in chemistry, particularly in
biochemistry and molecular biology, demand improved capabilities
for carrying out large numbers of reactions using small quantities
of materials.
[0004] In screening patients for genetic disease and
susceptibility, for example, the number of conditions for which
associated mutations are known is growing, and the numbers of
mutant alleles known to be associated with these conditions is
increasing. An adequate genetic screen for one or even a few of
these conditions can require testing a sample from the patient
against a very large number of genetic probes.
[0005] Enormous and rapidly increasing numbers of critical
biomolecules have been identified and characterized, and an
understanding of their various roles in cellular processes is
vastly improving. Consequently, for example, the number of
potential targets for pharmacologic intervention is very large.
Techniques for parallel chemical synthesis, such as combinatorial
chemistries, can efficiently produce libraries of large numbers of
synthetic compounds that may be screened against selected targets
in a rational drug design approach.
[0006] Considerable effort has been directed to developing better
approaches to handling large numbers of samples, reagents and
analytes. Automated laboratory workstations and robotics-based
systems have been brought to routine use for some chemical
manipulations in screening and synthesis, and dedicated computer
applications have been developed both for controlling processes and
for manipulating data. And a number of approaches have been
proposed for miniaturizing systems for carrying out chemical
processes, to reduce the quantities of the various components. Some
of these approaches have found use. Particularly, for example,
array technologies for binding pair assays use components
immobilized in arrays of features on a surface; and microfluidics
technologies employ networks of interconnected capillaries to move
and combine components on a very small scale.
[0007] There is significant and growing interest in employing array
technologies for conducting biomolecular manipulations. In array
techniques certain of the components are immobilized in a pattern
of array features on a surface of a solid support, and permitted to
interact with other components. Arrays of binding agents, in which
such binding agents as oligonucleotides or peptides are deposited
onto a support surface in the form of an array or pattern, can be
useful in a variety of applications, including gene expression
analysis, drug screening, nucleic acid sequencing, mutation
analysis, and the like. For example, information about the
nucleotide sequence of a target nucleic acid may be obtained by
contacting the target with an array of different surface-bound DNA
probes under conditions that favor hybridization of nucleic acids
having complementary sequences, and determining at what sites on
the array nucleic acid duplexes are formed. Hybridization to
surface-bound DNA probe arrays can provide a relatively large
amount of information in a single experiment. And, for example,
array technology can be useful in differential gene expression
analysis.
[0008] Such arrays may be prepared in any of a variety of different
ways. For example, DNA arrays may be prepared manually by spotting
DNA onto the surface of a substrate with a micro pipette. See,
Khrapko et al. (1991), DNA Sequence 1:375-388. Or, a dot-blot
approach or a slot-blot approach may be employed in which a vacuum
manifold transfers aqueous DNA samples from a plurality of wells to
a substrate surface. Or, an array of pins can be dipped into an
array of fluid samples and then contacted with the substrate
surface to produce the array of sample materials. Or, an array of
capillaries can be used to produce biopolymeric arrays, as
described for example in International Patent Publication WO
95/35505.
[0009] U.S. patent application Ser. Nos. 09/150,504 and 09/150,507
describe forming biomolecular arrays by adaptations of devices
employed in the printing industry and, particularly, of inkjet
print heads and of automated devices for moving a print head over a
print surface and for depositing the inks at desired locations on
the surface. These references and others cited herein, above and
below, are incorporated herein in their entirety by reference.
Other uses of inkjet printing devices to dispense biochemical
agents such as proteins and nucleic acids are suggested or
disclosed in, for example, U.S. Pat. Nos. 5,658,802; 5,338,688;
5,700,637; 5,474,796; 4,877,745; and 5,449,754.
[0010] Whether the miniaturized system is a microfluidic device or
an array, or is of some other design, at least some of the various
biomolecules to be introduced to the system are typically prepared
in depots remote from the receptacles by which they are introduced
to the system. These depots may take the form of a multiwell plate
(conventionally providing 96 wells in a 12.times.8 format), for
example, or a microtiter plate (conventionally providing 384 wells
in a 16.times.24 format, or 1536 wells in a 32.times.48 format). A
technical challenge is presented by the step of transferring the
liquids containing the various biomolecules from the depots to the
specific receptacles. In an array system constructed using an
inkjet printing technique, for example, a technical challenge is
presented by the need to transfer the liquids from the depots to
the specific reservoirs in the print head.
[0011] Conventionally a pipet may be employed to transfer a liquid
dropwise from a depot to a receptacle (such as a reservoir in a
microfluidics device or a reservoir in a print head). The tip of
the pipet is first dipped into the liquid in the depot and some of
the liquid is drawn into the pipet; then the pipet is moved to the
receptacle and a quantity of the liquid is expelled into the
receptacle. Several pipets may be ganged and used to transfer
several different liquids at once, to reduce the number of
repetitions, but problems of small dimension may make such an
approach impractical. In any event the transfer step results in
contamination of pipets, which accordingly must be either discarded
and replaced or decontaminated (for example by rinsing) before they
are used to transfer different liquids. Where a large number of
different liquids are to be moved, the transfer apparatus becomes
mechanically unwieldy, and the cost of minimizing the risk of
contamination is increased.
SUMMARY OF THE INVENTION
[0012] In one general aspect the invention features a method for
transferring liquids from a plurality of wells to one or more
receptacles, by displacing liquid contained in each well so that a
convex meniscus swells from the opening of the well, and contacting
a receptacle with the swollen meniscus to draw at least a portion
of the liquid into the receptacle. According to the invention, the
liquid transfer is effected directly from the depots to the
corresponding receptacles without contact between depots and the
receptacles, and without interposition of any transfer device
between depots and the receptacles. And, according to the
invention, the flow of the liquid into the receptacle following
contact of the receptacle with the meniscus is at least initially a
result of capillary interaction, and ordinarily is principally
so.
[0013] In some embodiments the wells are arranged in a specified
pattern in a depot member, so that where different wells contain
different liquids or contain liquids containing different
constituents, the different liquid contents are associable with the
positions of the wells in the pattern. And, in some embodiments
where liquids from different wells are to be transferred to
specified different receptacles, the receptacles are arranged in a
corresponding or complementary pattern, so that a specified
plurality of the wells may be aligned with a corresponding
specified plurality of the receptacles, so that transfer of the
liquids may be accomplished all at once from the specified wells to
the specified receptacles.
[0014] Accordingly in another aspect the invention features a
method for transferring liquids from a plurality of wells having
openings arranged in a selected format to a plurality of
receptacles arranged in a corresponding or complementary format, by
displacing the liquid contained in each well so that a convex
meniscus swells from the opening, and contacting the corresponding
receptacle with the swollen meniscus to draw a portion of the
liquid into the receptacles.
[0015] In some embodiments the liquid displacing step is carried
out by inwardly deforming a wall of each well to displace the
liquid; in preferred embodiments the wall is inwardly deformed by
application of mechanical or fluid pressure to the wall. In other
embodiments the liquid displacing step is carried out by
introducing a gas into a part of each well away from the opening;
in preferred embodiments the gas is introduced through a vent in a
part of the wall away from the opening, and in some embodiments the
gas is passed through a gas-permeable membrane covering the
vent.
[0016] In some embodiments the arrangements of the well openings
and the receptacles is such that receptacles to which transfer of
liquid is specified may come into contact with swollen menisci at
the openings of specified wells. In some embodiments the
arrangement of either the well openings or the receptacles is in a
generally planar format, and the step of contacting the receptacles
with the menisci is carried out by bringing the specified
receptacles with the menisci at the specified well openings. Or,
the arrangement of the well openings and the arrangement of
receptacles each is in a generally planar format, and the step of
contacting the receptacles with the menisci is carried out by
bringing the well openings into respective planes into generally
parallel proximity.
[0017] In another general aspect the invention features apparatus
for transferring a plurality of liquids, the apparatus including a
depot member having a plurality of wells each having an inwardly
deformable wall portion and an opening, in which the openings are
supported in a selected format, and a member defining a plurality
of receptacles in a corresponding or complementary format; means
for displacing liquid contained within the wells toward and through
the openings; and means for bringing well openings and receptacles
into proximity. According to the invention, transfer of liquid is
effected by deploying the displacing means to displace the liquid
in the well, causing a convex meniscus to swell outward from the
opening. When a receptacle which has been brought into proximity
contacts the swollen meniscus, the liquid is drawn into the
receptacle. The apparatus for effecting the transfer is
uncomplicated and can be made in a straightforward manner from
inexpensive materials using simple tools.
[0018] It can for some processes be advantageous to transfer a
multiplicity of liquids from a multiplicity of specified wells or
depots to a multiplicity of assigned or specified receptacles in a
single transfer operation. Accordingly in some embodiments the well
openings and the receptacles are arranged so that a multiplicity of
corresponding or complementary receptacles and wall openings can be
brought into proximity simultaneously, so that the receptacles
contact the respective menisci at nearly the same time. Where the
well openings are arranged in a generally planar pattern, for
example, liquid droplets expressed at a line of such wells may in
one step be transferred into a line of receptacles that are brought
into generally parallel proximity with the line of wall openings;
or, liquid droplets at a planar group of such wells may in one step
be transferred into a complementary group of receptacles,
themselves arranged in a generally planar pattern, that are brought
into generally parallel proximity with the group of well
openings.
[0019] Accordingly, in some embodiments the receptacle-defining
member is generally planar, and the well openings are supported in
a generally planar format. In some embodiments the
receptacle-defining member is an orifice plate of a print head and
the receptacles are in fluid communication with reservoirs in the
print head; and in some embodiments the print orifices are the
receptacles.
[0020] In some embodiments the wells include a deformable wall
portion, and the means for displacing the liquid in the wells
include means for inwardly deforming the deformable wall portion.
In some embodiments the wall-deforming means includes mechanical
means such as a plunger for pressing against an outer surface of
the deformable wall portion; or means for applying fluid pressure
(liquid or gas) at the outer surface of the deformable wall
portion.
[0021] In other embodiments each well includes a vent positioned
away from the opening, and means for introducing a fluid (gas or
liquid) through the vent and into the well, to displace the liquid
in the well toward the opening. In preferred embodiments the vent
is covered by a membrane that retains the liquid in the well under
operating conditions, but is permeable to the fluid to be
introduced through the vent into the well to displace the liquid in
the well.
[0022] In some embodiments the well includes a rigid wall portion
in addition to the deformable wall portion, and in some embodiments
the inwardly deformable wall portion and the rigid wall portion are
formed of a unitary piece of material. In some embodiments the
inwardly deformable wall portion includes a plastic or elastic
film. In some embodiments the inwardly deformable wall portion and
the support for the well openings are formed of a unitary piece of
material.
[0023] Other aspects and advantages of the invention will become
apparent from the following detailed description, taken together
with the accompanying drawings, illustrating by way of example the
principles of the invention.
DRAWINGS
[0024] FIG. 1A is a sketch of an embodiment of the invention in a
perspective view.
[0025] FIG. 1B is a sketch in a plan view of the embodiment of FIG.
1A.
[0026] FIG. 1C is a sketch in sectional view thru 1-1' of the
embodiment of FIG. 1B, showing in wells from left to right the
progress of forming a convex meniscus at the well opening by inward
displacement of a portion of the wall, and showing at right the
transfer of the liquid to a receptacle brought into contact with
the convex meniscus.
[0027] FIG. 2A is a sketch of an alternative embodiment of the
invention in a perspective view.
[0028] FIG. 2B is a sketch in sectional view thru 2-2' of the
embodiment of FIG. 2A, showing in wells from left to right the
progress of forming a convex meniscus at the well opening by inward
displacement of a portion of the wall by buckling or collapsing the
wall portion, and showing at right the transfer of the liquid to a
receptacle brought into contact with the convex meniscus.
[0029] FIG. 3 is a sketch in sectional view as thru 2-2' of an
embodiment as in FIG. 2A, showing in wells from left to right the
progress of forming a convex meniscus at the well opening by inward
displacement of a portion of the wall by partially turning the wall
portion inside out, and showing at right the transfer of the liquid
to a receptacle brought into contact with the convex meniscus.
[0030] FIG. 4A is a sketch of a further embodiment of the invention
in a perspective view.
[0031] FIG. 4B is a sketch in sectional view thru 4-4' of the
embodiment of FIG. 4A, showing in wells from left to right the
progress of forming a convex meniscus at the well opening by inward
displacement of a portion of the wall by inverting the wall
portion, and showing at right the transfer of the liquid to a
receptacle brought into contact with the convex meniscus.
[0032] FIGS. 5A-C are sketches in sectional view as for example in
FIG. 2B, showing stages in fabrication of the deformable wall
portions by pressing an array of mandrels against a plastic
film.
[0033] FIG. 6A is a sketch of a further embodiment of the invention
in a perspective view.
[0034] FIG. 6B is a sketch in sectional view thru 6-6' of the
embodiment of FIG. 6A, showing in wells from left to right the
progress of forming a convex meniscus at the well opening by
introducing a gas through a gas-permeable membrane covering a vent
in the wall, and showing at right the transfer of the liquid to a
receptacle brought into contact with the convex meniscus.
[0035] FIG. 7 shows a member with a plurality of receptacles
[0036] The drawings are for purposes of illustration, and the
figures are presented in diagrammatic form and are not made to
scale.
DETAILED DESCRIPTION
[0037] As the drawings show by way of illustration, the invention
is embodied in apparatus for direct non-contact transfer of fluids
from a plurality of depots, or wells, having openings arranged in a
specified pattern, to a plurality of receptacles arranged in a
corresponding or complementary pattern. In particular embodiments
the liquid contained in the wells is displaced so that a convex
meniscus swells outward from the openings, and the liquid flows
into the receptacles upon contact of the receptacle with the convex
meniscus. The flow of the liquid into the receptacle following
contact of the receptacle with the meniscus is at least initially a
result of capillary interaction.
[0038] Referring now to FIG. 1A, there is shown in a perspective
view an embodiment generally at 10 of a block 12 of depots 14, from
which liquids are to be transferred according to the invention to
reservoirs arranged in a corresponding pattern. In this
illustrative embodiment, as appears also in FIG. 1B, the depots 14
are arranged as wells of a standard 16.times.24 microtiter plate
(not all the wells are drawn in the Fig.). As may be understood
more clearly by reference to FIG. 1C, depot block 12 has a
generally planar surfaces 11 and 13, and each generally cylindrical
depot 14 is defined by a generally cylindrical rigid wall 16
passing from surface 11 through to surface 13 of depot block 12 and
having a generally circular opening 15 at surface 11 and a
generally circular opening 17 at surface 13. Depot block surface 13
is covered with a plastic or elastic film 18, which is sealed to
surface 13 at least at the margins of circular openings 17.
Accordingly, the circular depot openings 15 are arranged in a
generally planar pattern, and the portions of the elastic film 18
that cover the circular openings 17 form the deformable wall
portions 19 of the depots.
[0039] The embodiment of FIGS. 1A-1C can be employed in the method
of the invention as follows. Referring to FIG. 1C, which is a
composite showing a time course (t.sub.0 through t.sub.4) from left
to right, a quantity of liquid 100 is held in each depot. In
practice, the liquid in each depot may have a specified character,
or the liquid in each depot may contain a specified biomolecule or
reagent or analyte, or a specified mixture of biomolecules or
reagents or analytes. The liquids may simply be stored in the
depots, or they may have been prepared in the depots at least in
part. The depots may be entirely filled with the liquids or, as
illustrated in FIG. 1C (t.sub.0), they may be only partly full.
Transfer from a depot is initiated (t.sub.1) by applying a force
against the deformable wall portion 19, deforming it inward and
displacing the liquid 100 within the depot. The wall may be
deformed by any of a variety of means for applying force; one such
means, shown by way of illustration in FIG. 1C, is to press a
plunger 108 inwardly against the outer surface of the deformable
wall portion. The progressively increasing inward deformation of
the wall causes the meniscus 102 of the liquid to rise toward
(t.sub.1) and through (t.sub.2) the opening 15, forming a convex
meniscus 104. As the liquid 100 is further displaced (t.sub.3) the
convex meniscus 104 rises and swells as a droplet 106 of the liquid
is held by surface interaction away from the opening 15 and the
depot block surface 11. The transfer is completed (t.sub.4) by
contacting the swollen convex meniscus 104 with a receptacle 110,
which may for example be an orifice 112 in a planar receiving
member 114. Surface interaction of the receptacle 110 with the
liquid results in movement of the droplet of fluid 106 away from
the depot block surface 11 and the opening 15 and into the
receptacle 110.
[0040] As will be appreciated, a multiplicity of particular liquids
(or constituents in liquid carriers) can according to the invention
be rapidly and reliably transferred directly to assigned
receptacles (for example, to assigned reservoirs in a printing
device for constructing a biomolecular array; or to particular
reservoirs in a microfluidic device). The particular liquids are
held in particular depots whose positions in the depot block
correspond to the respective positions of the assigned receptacles
in the receiving member; the contents of the depots are displaced
to form droplets at the openings of the particular depots; and,
where transfer of a plurality of liquids at once is desired, the
receiving member is brought into parallel proximity to the depot
block surface so that the receptacles contact the menisci of the
respective droplets at nearly the same time.
[0041] As will be appreciated, a receptacle is in proximity to a
well or depot opening when it is close enough to make contact with
the swollen meniscus of a droplet at the opening. Where a meniscus
swells to a greater distance from the opening, proximity is reached
at a greater distance between the receptacle and the opening. In
practice there may be some variation in the distances to which the
various menisci swell away from the openings and, where a plurality
of droplets are to be transferred in a single transfer step, some
of the droplets may pass into their respective receptacles at
greater distances than other. Or, if the receptacles and the
openings are first brought to a given narrow separation, within the
range of distances to which the menisci may be expected to swell,
and then the displacement of the liquids progresses, some of the
droplets may contact the receptacles earlier than others. In either
event, a transfer step constitutes moving the receptacles and
openings together until the desired transfers of swollen droplets
have been effected, or holding the receptacles and openings at a
given narrow separation and then progressively swelling the
droplets of the liquids whose transfer is desired until all the
menisci have traversed the separation, contacted the receptacles,
and been drawn into the receptacles. As will be appreciated, the
distance to which a droplet may swell away from the opening depends
upon a variety of factors, including among others characteristics
of the liquid, characteristics of the surfaces at the openings,
shapes and dimensions of the openings, and the like. According to
the invention, the receptacle makes no contact with the opening
during the transfer.
[0042] Any of a variety of means can be employed for bringing
receptacles into contact with menisci according to the invention,
any of which will be within the knowledge of the person of ordinary
skill. They may be brought into proximity together by hand, for
example, by holding either the member supporting the wells or the
member supporting the receptacles, or both of them, in hand. As
will be appreciated, however, a straightforward mechanical method
may be preferred, to ensure precision and to complete the transfer
step more rapidly. Where the transfer is from a multiwell plate to
a printhead, for example, the mechanism 200 (see FIG. 7) that
positions and moves the printhead over the printed surface can also
be employed to bring the printhead and the multiwell plate into
proximity.
[0043] A prototype of the embodiment shown in FIGS. 1A-1C was
conveniently constructed by modification of a conventional
polystyrene microtiter plate, commercially available under the name
Greiner, generally as follows. First, the lower part of the
microtiter plate was cut away to remove the bottom parts of the
wells and to provide a depot block about 25 mm long and 25 mm wide
and 4 mm thick, having roughly square bores arranged in the
11.times.11 orthogonal pattern of the microtiter wells. The depots
were about 1.5 mm on each side and orthogonally adjacent depots
were spaced apart at 2.25 mm center-to-center. Then an elastomeric
film, of latex having 6 mil thickness, was affixed to the cut
surface of the depot block, and sealed using an epoxy, to provide
the deformable wall portions of the depots.
[0044] The prototype constructed in this fashion and having these
dimensions and operated generally as described above with reference
to FIG. 1C, using water as a liquid for purposes of demonstration,
proved capable of raising a convex meniscus to a height of about 1
mm away from the opening at the surface of the depot block. For
purposes of demonstration the orifice plate of a print head was
brought into generally parallel proximity to the surface of the
depot block, with the print head orifices approximately aligned
with the centers of the depots. As the orifice plate was moved
close enough to the depot block, the print head orifice contacted
the convex meniscus, and substantially all the liquid that had been
displaced through the opening was transferred into the print head
through the print head orifice.
[0045] As may be appreciated by one of skill in the art, and as
will be discussed in further detail below, other methods of
fabrication and other starting materials are contemplated, and
other dimensions and configurations for the depot block and the
depots and their various parts are within the scope of the
invention.
[0046] In the prototype described above an elastomeric material
constituted the deformable wall portion. In this construction, once
a transfer has been completed and the deforming force is removed
(for example, by withdrawing the plunger), the wall returns
elastically to approximately its original shape. This permits
re-use of the device, which may be desired for example where
aliquots of the liquid are to be transferred at time intervals or
following a sequence of treatment steps in the depot.
Alternatively, a plastic material may be used for the deformable
wall portion and, in this construction, the deformed wall does not
return to its original shape.
[0047] A variety of different configurations are made possible by
employing a nonelastomeric material for the deformable wall
portion. Illustrative examples are shown in FIGS. 2A and 2B; FIGS.
3A and 3B; and FIGS. 4A and 4B. Each of these illustrative
embodiments is a laminate structure that includes as one lamina a
plastic film that has been shaped to provide the desired deformable
walls.
[0048] A preferred cold-forming method for shaping the film is
described by reference to FIGS. 5A-5C. Referring to FIG. 5A, the
starting material is a piece of plastic film 52, which is
dimensioned to accommodate the desired pattern of depots. A press
54 is provided, consisting of mandrels 58 projecting from a block
member 56. The press 54 is then moved against a surface 53 of the
film 52, such that the mandrels 58 press into and shape the film,
as shown in progress in a time sequence (t.sub.0 through t.sub.3)
for a single depot in sectional view in FIG. 5B. A die 59 may be
provided to support the film during the cold-forming process. The
shaping is continued until the desired shape 50 is complete, as
shown in sectional view in FIG. 5C. The press is then removed from
the film, causing the mandrels to withdraw from the now-shaped
depot walls 57, as shown in sectional view in FIG. 5C. The shapes
and dimensions of the mandrels 58 are made to provide the desired
shapes for the depots they form; and the positions of the mandrels
58 on the block member 56 correspond to the desired pattern of the
wells. An illustrative example of a completed cold-formed structure
appears in FIG. 5C, showing deformable depot walls 57 having
openings 55 onto what remains of the surface 53 of the starting
film 52. The deformable walls 57 are by virtue of attenuation
during the cold-forming process made thinner than the original film
52. The desired thickness of the deformable walls 57 can be
determined as a matter of design routine; it depends principally
upon the characteristics of the particular plastic material used,
the dimensions of the deformable wall portion, and the design and
construction of the means for deforming the wall. As will be
appreciated, the unattenuated portion of the original film that
remains among the openings 55 of the deformable walls 57 supports
the desired structure 50, and it may be sufficiently rigid to serve
as a depot block in the course of the transfer process. More
usually, however, further support will be required, as in the
exemplary embodiments described below.
[0049] Referring now to FIGS. 2A and 2B, there is shown an
embodiment in which a shaped film 20, cold-formed as described
above with reference to FIGS. 5A-5E to make openings 55 and
deformable depot walls 57, which depend from what remains among the
openings of the original film 52. In this embodiment the shaped
film 20 is supported by a block 12, which conveniently may have
served as a die 59 during the cold-forming process. The deformable
walls 57 constitute the depots 29, and the generally circular
openings 55 form the openings 25 at the surface 21 at which the
droplets are formed during the transfer process. That is, the
liquid in the depots is confined within and is transferred from the
deformable depot walls in this embodiment.
[0050] The embodiment of FIGS. 2A and 2B can be employed in the
method of the invention as follows. Referring to FIG. 2B, which
generally as in FIG. 1C is a composite showing a time course
(t.sub.0 through t.sub.4) from left to right, a quantity of liquid
100 is held in each depot. As described above with reference to
FIG. 1C, the depots may be entirely filled with the liquids or, as
illustrated in FIG. 2B (t.sub.0), they may be only partly full.
Transfer from a depot is initiated (t.sub.1) by applying a force
against the deformable wall portion 29, deforming it inward and
displacing the liquid 100 within the depot. The wall may be
deformed by any of a variety of means for applying force; one such
means, shown by way of illustration in FIG. 2B, is to press a
plunger 108 inwardly against the outer surface of the deformable
wall portion. This results in a progressive collapse (t.sub.1
through t.sub.3) of the deformable wall portion 29, which causes
the meniscus 102 of the liquid to rise toward (t.sub.1) and through
(t.sub.2) the opening 25, forming a convex meniscus 104. As the
liquid 100 is further displaced (t.sub.3) the convex meniscus 104
rises and swells as a droplet 106 of the liquid is held by surface
interaction away from the opening 25 and the depot block surface
21. The transfer is completed (t.sub.4) by contacting the swollen
convex meniscus 104 with a receptacle 110, which may for example be
an orifice 112 in a planar receiving member 114. Surface
interaction of the receptacle 110 with the liquid results in
movement of the droplet of fluid 106 away from the depot block
surface 21 and the opening 25 and into the receptacle 110.
[0051] FIG. 3 shows a liquid transfer process employing an
embodiment constructed generally as in FIG. 2B, except this process
employs a plunger 118 shaped to turn the deformable wall portion 29
partially inside out, rather than collapse it. This manner of
deformation may be preferred for some deformable wall materials and
deformable wall thicknesses, to provide adequate displacement of
liquid without rupture of the wall.
[0052] FIGS. 4A, 4B show yet another embodiment, which may be
viewed as a structural hybrid of the embodiments of FIGS. 1A and
2C. In this embodiment a shaped film 40 is interposed between an
exit block 42 and a support block 48. Exit block 42 is provided
with generally cylindrical bores having cylindrical rigid walls 46,
opening by way of generally circular openings 45 at surface 41. As
is described generally with reference to FIGS. 2A and 2B, shaped
film 40 is cold-formed to make deformable wall portions 49, which
depend into generally cylindrical bores in support block 48, which
may conveniently have served as a die 59 during the cold-forming
process. As will appear from inspection of FIG. 4B, the fluid
capacity of the depots 44 in this embodiment includes both the
cylindrical volume enclosed within the rigid cylindrical walls 46
and the volume enclosed by the depending deformable wall portions
49.
[0053] As shown in a composite showing a time course from left to
right, generally as shown in FIG. 2A, transfer from a depot 44 is
initiated (t.sub.1) by applying a force against the deformable wall
portion 49, deforming it inward and displacing the liquid 100
within the depot. The wall may be deformed by any of a variety of
means for applying force; one such means, shown by way of
illustration in FIG. 4B, is to press a plunger 108 inwardly against
the outer surface of the deformable wall portion. This results in
progressively collapsing the deformable wall portion 49 and then
turning it inside out (t.sub.1 through t.sub.3). This causes the
meniscus 102 of the liquid to rise toward (t.sub.1) and through
(t.sub.2) the opening 45, forming a convex meniscus 104. As the
liquid 100 is further displaced (t.sub.3) the convex meniscus 104
rises and swells as a droplet 106 of the liquid is held by surface
interaction away from the opening 45 and the depot block surface
41. The transfer is completed (t.sub.4) by contacting the swollen
convex meniscus 104 with a receptacle 110, which may for example be
an orifice 112 in a planar receiving member 114. Surface
interaction of the receptacle 110 with the liquid results in
movement of the droplet of fluid 106 away from the depot block
surface 41 and the opening 45 and into the receptacle 110.
[0054] FIGS. 6A, 6B show an alternative embodiment of the
invention, in which displacement of the liquid in the depot is
accomplished by introducing a gas into the depot by way of a vent,
forming a bubble. The structure, shown generally at 60, is similar
to that illustrated in FIGS. 1A-1C, except that a gas-permeable
membrane is provided in place of the deformable elastomeric film.
Referring now to FIGS. 6A and 6B, a block 62 contains generally
cylindrical depots 64, each defined by a generally cylindrical
rigid wall 66 passing from surface 61 through surface 63, and
opening by way of generally circular openings 65 and 67 in surfaces
61 and 63, respectively. Depot block surface 63 is covered by a
gas-permeable membrane 68, which is sealed to the surface 63 at
least at the margins of circular openings 67. Gas-permeable
membrane 68 inhibits escape of the liquid out from the depot, but
permits passage of a gas into the depots by way of circular
openings 67, which accordingly serve as vents.
[0055] As appears in a time course composite (t.sub.0 through
t.sub.4) in FIG. 6B, the liquid in depot 64 is displaced by
introducing the gas under pressure by way of the vents 67 through
the membrane 68 to form (t.sub.1) a second meniscus 124, concave
with respect to the liquid, which, as a gas bubble 126 forms
(t.sub.2), advances away from the vent 67, displacing the liquid
100 away from the vent and toward the opening 65. As the liquid is
further displaced (t.sub.3) the convex meniscus 104 rises and
swells as a droplet 106, which is then transferred (t.sub.4) upon
contact with the receptacle 110.
[0056] Suitable membrane materials may be selected by resort to
materials specifications for commercially available membranes, for
example, and tested using any desired displacement fluid without
undue experimentation. Alternatively, the openings 67 may be
covered by an impermeable material which is perforated to admit
passage of the displacement fluid but not of the liquid to be
transferred from the depot. Any fluid (liquid or gas) can be
employed to displace the liquid 100, and the displacement fluid
need not necessarily form a second meniscus 124. However, where it
is desirable to minimize mixture of the displacement fluid with the
liquid to be transferred from the depot, a relatively insoluble gas
or immiscible liquid may be preferred.
[0057] The invention proves particularly useful for transfer of
different liquids from a multiplicity of depots having openings
arranged in a generally planar format to a multiplicity of
receptacles, which may be correspondingly arranged in a generally
planar format. The invention may be particularly useful for
transferring liquids from arrays of preparative wells or storage
depots, such as microtiter plates and the like, to receptacles on a
surface of a microfluidics device or to apertures on the orifice
surface of printing device employed in array deposition.
[0058] For transfer of liquids to a print head, U.S. patent
application Ser. Nos. 09/150,504 and 09/150,507 disclose loading
the reservoirs of a printhead by way of the print orifices or other
orifices in the orifice plate. For loading of nucleic acid
compositions, for example, the orifice plate is contacted with the
nucleic acid composition under conditions sufficient for fluid to
flow through the orifice and into the firing chamber and reservoir
of the head, where fluid flow is due, at least in part, to
capillary forces. The invention provides for clean and
straightforward presentation of a multiplicity of liquids such as
nucleic acid compositions or other biomolecular preparations for
contact with selected orifices in the orifice plate.
[0059] Other embodiments are within the following claims. For
example, the depots may be arranged in other formats, standard to
biochemistry and molecular biology or not. For transfer of a
multiplicity of liquids in a single transfer step, all that is
required of the format is that the depot openings and the
receptacle openings be arranged in a format that permits bringing a
multiplicity of receptacles into contact with the multiplicity of
swollen menisci nearly all at once. That is, the respective
receptacles and depot openings need only be arranged such that they
can be brought into generally parallel proximity in a single
transfer step.
[0060] For example, either the depot openings or the receptacles
can be arranged on or in a generally planar support, and the other
can be arranged generally on or in a cylindrical support; and the
cylindrical support can be rotated about an axis parallel to the
planar support and translated over it as if it were rolling upon an
imaginary plane sufficiently close to the planar support that the
receptacles contact swollen menisci at the depot openings and draw
up the droplets as the movement progresses. Or, the depot openings
and the receptacles each can be arranged on or in a generally
cylindrical support, and the cylinders can be rolled to bring
succeeding receptacles into contact with succeeding menisci. Other
configurations will be apparent, and are within the scope of the
invention.
[0061] And, for example, while the embodiments described herein by
way of illustration generally have a laminate construction, in
which for example the deformable depot walls are constructed from a
film which is then affixed to a supporting member, it will be
appreciated that any of the described embodiments may be
constructed by forming the deformable walls and the supporting
member or the deformable walls and the orifice block as unitary
piece using techniques known in the plastics art. Such techniques
include, for example, injection molding. The desired mechanical
characteristics of the resulting parts may without undue
experimentation be obtained by selection of suitable starting
materials and configuration and dimensions.
[0062] The size of each orifice in the orifice plate is one that
produces a spot of suitable dimensions on the substrate surface,
where the orifice generally has an exit diameter (or exit diagonal
depending upon the particular format of the device) in the range
about 1 .mu.m to 1 mm, usually about 5 .mu.m to 100 .mu.m, and more
usually about 10 .mu.m to 60 .mu.m. A means may be associated with
each orifice for propelling fluid through the associated orifice
from a delivery chamber that is in fluid conducting relationship
with the orifice. In some embodiments the propelling means propels
the fluid through the associated orifice by forming a bubble that
displaces the fluid; particular bubble-forming means include a
source of heat such as an electrical resistor. In other embodiments
the propelling means propels the fluid through the associated
orifice by electromechanical displacement; particular
electromechanical displacement means include a piezoelectric
device.
[0063] And, for example, where the dimensions of a reservoir
connected to the receptacle are small, or where channels leading
from a receptacle to a reservoir are of small dimension or follow a
long or tortuous path, loading of the channels or of the reservoir
may be facilitated by applying a reduced pressure within the
channel or reservoir to assist movement of the liquid through the
receptacle. The transfer is preferably initiated, however, by
capillary forces acting upon contact of the swollen meniscus with
the receptacle.
* * * * *