U.S. patent application number 12/748847 was filed with the patent office on 2010-07-15 for confinement of fluids on surfaces.
This patent application is currently assigned to INTERNATIONAL BUSINESS MACHINES CORPORATION. Invention is credited to Emmanuel Delamarche, David Juncker, Heinz Schmid.
Application Number | 20100176089 12/748847 |
Document ID | / |
Family ID | 34935140 |
Filed Date | 2010-07-15 |
United States Patent
Application |
20100176089 |
Kind Code |
A1 |
Delamarche; Emmanuel ; et
al. |
July 15, 2010 |
CONFINEMENT OF FLUIDS ON SURFACES
Abstract
The invention is directed to a device for applying a fluid to a
surface, the device comprising a first conduit for directing a flow
of a first fluid towards the surface and a second conduit for
directing a flow of a second fluid away from the surface, the first
conduit being arranged relative to the second conduit such that in
operation of the device the second fluid comprises substantially
the first fluid, and wherein said first conduit comprises a first
aperture and the second conduit comprises a second aperture, the
first aperture arranged at a distance from the second aperture.
Inventors: |
Delamarche; Emmanuel;
(Thalwil, CH) ; Juncker; David; (Zurich, CH)
; Schmid; Heinz; (Waedenswil, CH) |
Correspondence
Address: |
RYAN, MASON & LEWIS, LLP
1300 POST ROAD, SUITE 205
FAIRFIELD
CT
06824
US
|
Assignee: |
INTERNATIONAL BUSINESS MACHINES
CORPORATION
Armonk
NY
|
Family ID: |
34935140 |
Appl. No.: |
12/748847 |
Filed: |
March 29, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10841390 |
May 7, 2004 |
|
|
|
12748847 |
|
|
|
|
Current U.S.
Class: |
216/90 ;
156/345.18; 216/83 |
Current CPC
Class: |
C40B 60/14 20130101;
B82Y 30/00 20130101; B01J 19/0046 20130101; B01J 2219/00677
20130101; B01J 2219/00605 20130101; B01J 2219/00468 20130101; B01J
2219/0038 20130101; B01J 2219/00353 20130101; B01J 2219/00675
20130101; C23F 1/08 20130101; B01J 2219/00722 20130101; B01J
2219/00637 20130101; B01J 2219/00585 20130101; C40B 40/06 20130101;
B01J 2219/00743 20130101; B01J 2219/0061 20130101; B01J 2219/00612
20130101; B01J 2219/00418 20130101; B01J 2219/00369 20130101; B01J
2219/00596 20130101; C40B 50/14 20130101; B01J 2219/00621 20130101;
B01J 2219/00367 20130101 |
Class at
Publication: |
216/90 ;
156/345.18; 216/83 |
International
Class: |
C23F 1/08 20060101
C23F001/08; C23F 1/00 20060101 C23F001/00 |
Claims
1. A device for applying a liquid to a surface immersed in an
environmental liquid, said device comprising: a first conduit for
directing a flow of a first liquid towards a surface and a second
conduit for directing a flow of a second liquid away from said
surface, wherein said first conduit has a first aperture that is
arranged at a distance (d) from a second aperture of said second
conduit, said device further comprising one or more of a first flow
controller for controlling one or more of a first flow rate and a
first pressure (p3) of said first liquid, and a second flow
controller for controlling one or more of a second flow rate and a
second pressure (p4) of said second liquid, said first conduit
being arranged relative to said second conduit such that in
operation said second liquid comprises substantially said first
liquid, whereby said device is configured to hydrodynamically
confine a flow of a liquid between said first aperture, said second
aperture and said immersed surface.
2. The device of claim 1, further comprising one or more of a first
liquid container for said first liquid and a second liquid
container for said second liquid.
3. The device of claim 1, wherein said first flow controller is
further configured to provide a dispense rate that results in a
laminar flow.
4. The device of claim 1, wherein one or more of said first flow
controller and said second flow controller are further configured
to respectively provide one or more of first and second pressures
(p3, p4) and first and second flow rates such that, in operation,
said first liquid is drawn towards said second aperture.
5. The device of claim), further comprising a filter for
regenerating said first liquid from said second liquid.
6. The device of claim 1, further comprising an applicator head,
wherein said first conduit and said second conduit are arranged at
said applicator head.
7. The device of claim 6, comprising a drive for moving said
applicator head relative to said surface.
8. The device of claim 6, wherein at least one of said first
aperture and said second aperture of said conduits is arranged in a
recession of said applicator head.
9. The device of claim 8, wherein said first aperture and said
second aperture are arranged in said recession, serving as a flow
path, and wherein said flow path is not straight.
10. The device of claim 1, wherein said device is configured such
that said first aperture and said second aperture can be located at
a substantially identical distance from said surface.
11. The device of claim 1, comprising a third conduit for directing
a flow of a third fluid, wherein said third conduit is configured
to influence said flow of said first liquid in its flow
direction.
12. The device of claim 1, comprising a distance element for
determining said distance between said apertures and said
surface.
13. The device of claim 1, wherein said device is of unitary
construction.
14. A method for applying a first liquid to a surface, said method
comprising: locating a device proximal to said surface, wherein
said device comprises a first conduit for directing a flow of a
first liquid towards a surface and a second conduit for directing a
flow of a second liquid away from said surface, wherein said first
conduit has a first aperture that is arranged at a distance (d)
from a second aperture of said second conduit, said device further
comprising one or more of a first flow controller for controlling
one or more of a first flow rate and a first pressure (p3) of said
first liquid, and a second flow controller for controlling one or
more of a second flow rate and a second pressure (p4) of said
second liquid, said first conduit being arranged relative to said
second conduit such that in operation said second liquid comprises
substantially said first liquid, whereby said device is configured
to hydrodynamically confine a flow of a liquid between said first
aperture, said second aperture and said immersed surface; and
applying said first liquid to said surface via said device.
15. The method of claim 14, further comprising a step of varying
said flow of said first liquid during said supply of said first
liquid to said surface.
16. The method of claim 14, further comprising a step of moving
said device relative to said surface with said first liquid
contacting said surface.
17. The method of claim 16, comprising orienting said device
relative to said surface such that traces of said first liquid
produced as said device is moved relative to said surface remain
one of separate and overlap.
18. The method of claim 14, wherein said step of locating comprises
said step of locating an array of a plurality of said devices
proximal to said surface; said method further comprising said steps
of: supplying said first liquid to said surface, in at least one
device of said array, flowing said first liquid via a flow path
from said first conduit towards said second conduit; and moving
said array relative to said surface with said first liquid in each
aperture contacting with said surface.
19. The method of claim 18, further comprising a step of varying
said flow of said first liquid during said supply of said first
liquid to said surface in at least one device of said array.
20. The method of claim 14, wherein said step of locating comprises
a step of locating said device near a particle in said
environmental liquid, said method further comprising operating said
device to remove said particle by means of said first liquid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/841,390, filed May 7, 2004, incorporated by
reference herein.
FIELD OF THE INVENTION
[0002] The present invention generally relates to confinement of
fluids on surfaces and particularly relates to methods and
apparatus for applying and confining fluids to surface areas. Even
more particularly the invention relates to locally processing a
surface for both additive and subtractive patterning of materials
while the surface is immersed in a fluid.
BACKGROUND OF THE INVENTION
[0003] There are many applications in which it is desirable to
apply a fluid to a surface. An example of such an application is in
patterning or other processing of surfaces. Patterning and
processing of surfaces with fluids is becoming increasingly
important in a range of fields, including chemistry, biology,
biotechnology, materials science, electronics, and optics.
Patterning a surface by applying a fluid to the surface typically
involves confinement of the fluid to defined regions of the
surface.
[0004] A surface is typically wettable by a fluid if the contact
angle between a drop of the fluid and the surface is less than 90
degrees. A channel for carrying a fluid is typically wettable if
the channel exerts a negative pressure on the fluid when partially
filled. Such a negative pressure promotes filling of the channel by
the fluid. In a channel having a homogeneous surface, a negative
pressure arises if the contact angle between the fluid and the
surface is less than 90 degrees. A surface is typically regarded as
being more wettable if the contact angle between the surface and
the fluid is smaller, and less wettable if the contact angle
between the surface and the fluid is higher.
[0005] One conventional surface patterning technique is
lithography. In lithography, a mask is usually applied to a surface
to be patterned. Apertures are formed in the mask to define regions
of the surface to be exposed for treatment. Areas of the surface
remaining covered by the mask are protected from treatment. The
mask is typically formed from a patterned layer of resist material.
The surface carrying the mask may then be immersed in a bath of
chemical agents for treatment of the exposed regions. Lithography
is a relatively expensive process to perform, involving multiple
steps, expensive instruments and laboratory facilities with
controlled environments. With the possible exception of in situ
synthesis of short deoxyribonucleic acid (DNA) strands, lithography
is generally unsuitable for handling and patterning biomolecules on
surfaces. Lithography is also unsuitable for simultaneously
processing surfaces with different chemicals in parallel, as
described by Whitesides, Annu. Rev. Biomed. 3 (2001), 335-373.
There can be incompatibility between different process steps or
chemicals used in lithography and between various surface layers
processed by lithography.
[0006] Another conventional surface patterning technique is drop
delivery. Drop delivery systems, such as pin spotting systems, ink
jet systems, and the like, typically project a relatively small
volume of fluid onto a specific location on a surface. See, M.
Shena, "Microarray Biochip Technology," Eaton Publishing (2000).
However, these systems have limited resolution due to spreading of
dispensed drops on the surface. Additionally, the quality of
patterns formed by such systems is limited by drying of the
delivered fluid, as is described by J. T. Smith, Spreading Diagrams
for the Optimization of Quill Pin Printed Microarray Density, 18
LANGMUIR 6289-293 (2002). Further, these systems are generally not
useful for dissolving or extracting materials from a surface, do
not facilitate a flow of fluid over a surface and are not suited to
process a surface sequentially with more than one fluid.
[0007] PCT WO 01/63241 A2 describes a surface patterning technique
involving use of a device having a channel with a discharge
aperture. A matching pillar is engaged with the discharge aperture
to promote deposition of molecules on a top surface of the pillar.
However, it is not possible to vary patterning conditions for
different pillars individually. Exposure of the pillar surface to
the fluid should be long enough to allow reagents to reach the
surface by diffusion. The method also requires a surface with
pillars matching the aperture. Precise alignment of the device with
the pillars before engagement is required. Spacing between the
discharge aperture and the pillars needs external control. The
pillars cannot be moved on the surface to draw lines.
[0008] Another conventional surface patterning technique involves
application of a microfluidic device to a surface. An example of
such a device is described in U.S. Pat. No. 6,089,853 issued to
Biebuyck et al. (hereinafter "Biebuyck"). The microfluidic device
can establish a flow of fluid over a surface. The flow can be
created via capillary action in the device. The device can be used
to treat a surface with different fluids in parallel. However, the
device must be sealed to the surface to be treated to confine the
fluid(s) to the region(s) of the surface to be treated. Confinement
of the fluid(s) allows for the formation of patterns with
relatively high contrast and resolution. High contrast and
resolution are desirable qualities when biomolecules are patterned
on a surface for biological screening and diagnostic purposes.
[0009] The device is placed on the surface to be treated and sealed
around the processing regions before being filled with treatment
fluid. However, if the flow is created by capillary action, several
notable disadvantages result. First, service ports in the device
must be filled with treatment fluid for each patterning operation.
Also, only one fluid can be delivered to each channel in the device
and cannot be flushed out of the channels before separation of the
device from the surface. Further, the fluid tends to spread away
from the regions of the surface to be treated during removal of the
device from the surface. Therefore, the device is not suitable for
processing a surface sequentially with several fluids.
[0010] If the flow is created by external actuation, such as by
pressurization, electric fields, or the like, several other notable
disadvantages result. For example, an individual connection from
the actuator must be made to each channel in the device. These
connections, e.g., to peripheral equipment, limit the density of
channels that can be integrated into the device and addressed
individually. Pumping, valving and control complexity increase as
the number of channels increases. External connections create dead
volume between the device and external actuators because of the
intervening conduits.
[0011] Another microfluidic device for localized processing of a
surface is described in IBM Technical Disclosure Bulletin reference
RD n446, Article 165, Page 1046. The device is similar to that
described in Biebuyck. It permits several fluids to be flushed in
sequence over the same surface area without requiring separation of
the device from the surface. Such a device is thus useful for
chemical and biological reactions involving the sequential delivery
of several fluids. However, the device must be sealed around the
surface to be treated before filling. Further, the fluids cannot be
filled prior to the device being applied to the surface. Each
additional step requires supplementary filling of the relevant
fluid. Further, the lines in the device need to be prestructured
via lithography and cannot be readjusted subsequently.
[0012] Another conventional device for confining fluids to a
predefined pattern between a top and bottom surface without
involving a seal is described in European Patent 0 075 605. This
device is useful for performing optical analysis of the confined
fluid. However, the device requires predefined topographical or
chemical patterns on both the top and bottom surfaces. Also, the
device, having no inlet or outlet ports, is not suitable for the
transport of fluids.
[0013] Another device for guiding fluids along a predetermined path
is described in WO 99/56878. This device can flow several fluids
simultaneously over a surface without involving a seal to confine
the fluids. However, separation gaps between the paths have to be
capillary inactive. This limits path sizes to greater than one
millimeter (mm). Otherwise, meniscus pressures produce uncontrolled
spreading of the fluids. Further, the fluid is not retained after
separation and can instead spread over the surface, fluid delivery
requires an external connection to each path and cumbersome
peripheral flow control devices are required.
[0014] Yet another method for guiding fluid along a surface without
involving a seal is described in B. Zhao et al., Surface-Directed
Liquid Flow Inside Microchannels, 291 SCIENCE 1023-26 (2001). In
this method, a surface is patterned with a wettability pattern.
Specifically, two wettable patterns mirroring each other are
defined on otherwise non-wettable top and bottom surfaces. This
produces "virtual" channels without lateral walls, that can have a
micrometer width. However, this method requires wettability
patterns on both the top and bottom surfaces. In other words, the
path for the flow of fluid must be predetermined using lithography,
which is expensive and lacks flexibility. Furthermore, subsequent
readjustment of the flow paths cannot be performed.
[0015] Further, the contrast in wettability between the two
patterns needs to be very high, both non-wettable areas are
required on both the top and bottom surfaces and highly wettable
areas are required within the virtual channel. The two patterns
have to match each other exactly in shape and alignment. Capillary
action can be used to fill the channels, but the fluid cannot be
removed or exchanged. This method is also susceptible to
uncontrolled spreading of fluid because it is relatively difficult
to produce sufficiently non-wettable surfaces.
[0016] A double pipette system might be employed for local
controlled drug infusion. See for example, O. Feinerman, A
Picoliter "Fountain Pen" Using Co-Axial Dual Pipettes, 127 JOURNAL
OF NEUROSCIENCE METHODS 75-84 (2003). Namely, two concentric
pipettes can be manipulated separately and pressurized
independently by a designated double holder. The inner pipette is
loaded with a desirable solution, and functions as a source, while
the outer pipette serves as a sink. This configuration provides for
a flow of solution between the two pipettes that protrudes only a
small distance into the surrounding fluid and does not diffuse
away. However, without moving the pipette the infusion only occurs
only briefly and does not allow for the creation of a
two-dimensional pattern.
[0017] In WO 01/49414 a dual capillary system is described that can
be used to provide a resolubilizing fluid onto a surface of a
substrate. A second capillary element is then used to draw the
material from the surface of the substrate into the analysis
channel of a microfluidic device. The capillaries are disposed
adjacent to one another such that fluid is delivered from one
capillary and drawn up into, e.g., sampled by, the other capillary
without moving the microfluidic device or the substrate. Fluid is
expelled from the fluid delivery capillary onto a sample material
surface whereupon the sample material is at least partially
resolubilized in the expelled fluid. A portion of the fluid on the
substrate with the resolubilized sample material is then drawn into
the analysis channel.
[0018] This system is designed to have the smallest distance
possible between the capillaries such that the resolubilized sample
material in the expelled fluid is received close to the fluid
delivery capillary. The dual capillary system is not be moved over
the sample surface during either delivery or sampling of the fluid.
For this resolubilizing technique to function properly, there is to
be some delay between delivery and sampling of the fluid. Further,
sampling comprises drawing only a portion of the resolubilized
material into the sampling capillary.
[0019] Therefore, it would be desirable to provide a technique for
confining a fluid on a surface in a manner that allows the
technique to be used to create two-dimensional patterns.
SUMMARY OF THE INVENTION
[0020] According to a first aspect of the present invention, a
device is provided for applying a fluid to a surface, also referred
to as fluid pattern creator. The device comprises a first conduit
for directing a flow of a first fluid towards a surface and a
second conduit for directing a flow of a second fluid away from
said surface. The first conduit is arranged relative to the second
conduit such that in operation the second fluid comprises
substantially the first fluid, and wherein the first conduit has a
first aperture that is arranged at a distance from a second
aperture of the second conduit. The first aperture is also referred
to as discharge aperture, the second aperture is also referred to
as aspirator aperture.
[0021] This device allows for the hydrodynamical confinement of the
flow of a processing fluid between the discharge aperture, the
aspirator aperture and a surface. Thereby a pattern can be created
that corresponds to the flow path of the first fluid from the first
conduit towards the second conduit. This technique is feasible even
at micrometer resolution. This fluid pattern creator can also be
used to confine and transport the first fluid over a surface that
is immersed in the same or a different fluid, and can find
application in surface and/or particle treatment/patterning for,
e.g., microelectronics, optics, biology and biochemistry.
[0022] In a preferred embodiment, the fluid pattern creator may
comprise a first fluid container for the first fluid and/or a
second fluid container for the second fluid. Having a first fluid
container and/or a second fluid container makes the fluid pattern
creator independent from a remote fluid container, allowing the
fluid pattern creator to be used in a more mobile manner.
[0023] In another preferred embodiment, the fluid pattern creator
may further comprise a first flow controller for controlling a
first flowrate or a first pressure of the first fluid and/or a
second flow controller for controlling a second flowrate or a
second pressure of the second fluid. The flow controller(s) can be
used to control fluid flow, for example, to increase the amount of
fluid per unit time that comes in contact with the surface, or to
reduce the amount of fluid, other than the first fluid, that is
contained in the second fluid.
[0024] The fluid pattern creator may preferably be set up in such a
way that the first and second pressures are tuned to draw the first
fluid towards the second aperture. Drawing the first fluid towards
the second aperture increases the precision of the pattern
created.
[0025] If the fluid pattern creator comprises a filter for
regenerating the first fluid from the second fluid, the resulting
first fluid can be reused for patterning, thus reducing the amount
of wasted fluid. In this exemplary embodiment, a container for the
first fluid can be smaller, since it needs to store a lesser volume
of first fluid.
[0026] If the conduits are arranged at an applicator head the head
may be positionable near the surface via head controllers, allowing
more flexibility in handling devices with a surface to be
patterned. In particular the fluid pattern creator could comprise a
means, e.g., drive, for moving the applicator head relative to the
surface. Being able to move the applicator head allows for easier
positioning during creation of a desired pattern. Namely, it allows
for movement of the applicator head during patterning, allowing for
the creation of a larger variety of patterns.
[0027] If at least one of the apertures of the conduits is arranged
in a recess of the applicator head, the flow of the fluid can be
better controlled and decoupled from an environmental fluid. In a
preferred embodiment, the first and the second aperture are
arranged in the recess, serving as a flow path. In this embodiment,
the flow path is not straight, e.g., curved. The form of the recess
shapes the form of the flow path. When the flow path is not
straight, a larger variety of patterns can be obtained without
active flow-path-shaping means.
[0028] If the first aperture and the second aperture are arranged
at a substantially identical distance from the surface, the flow of
the first fluid towards the second aperture (i.e., from the first
aperture) will be homogeneous, thereby allowing for an accurate
determination of an amount of the first fluid coming into contact
with the surface. The ability to accurately determine this amount
is beneficial for assessing chemical interaction between the first
fluid and the surface.
[0029] In an exemplary embodiment, a third conduit is arranged for
directing the flow of a third fluid in such a way that the flow of
the third fluid influences the flow direction of the first fluid.
The third fluid can be selected to be an influencer, acting as an
active forming means for the flow path, and/or to have a
predetermined reactive characteristic, allowing the third fluid to
become a part of the patterning process. For instance the third
fluid can react with the first fluid, rendering the first fluid
weaker or stronger, and thus changing the intensity of reaction and
the pattern that is eventually created. The third fluid can also
react with the surface to modify the pattern created by the other
fluid(s).
[0030] The fluid pattern creator preferably comprises a distance
element for determining the distance between the apertures and the
surface. This distance element provides an efficient means to
ensure that the distance between the apertures and the surface is
kept constant. Maintaining a constant distance between the
apertures and the surface results in a more predictable
pattern.
[0031] If the fluid pattern creator comprises a unitary
construction, e.g., manufactured from a single piece of material,
the fluid pattern creator is both robust and more easily produced.
At the same time, mechanical tolerances are not a critical issue,
the resulting fluid pattern creator exhibits a higher degree of
precision and alignment that is achievable. Alignment is a critical
issue to create precise patterns on a surface.
[0032] In an exemplary embodiment, the first pressure is tuned such
that the first fluid is retained in the first fluid container when
the first aperture is remote from the surface. When the first
aperture is moved to be proximal to the surface, pressure may be
varied, e.g., applied, to initiate flow of the first fluid out of
the first aperture and onto the surface. When the device is
withdrawn from the surface, the first pressure may then again be
tuned to draw back excessive fluid from the surface. Further, there
may be a plurality of first fluid containers, each coupled to the
first aperture, wherein the pressure for the first fluid in each of
the plurality of first fluid containers is controlled, in parallel
or individually.
[0033] The first or second pressure may be generated by external
pumps, such as syringe pumps or peristaltic pumps, by integrated
pumps, such as microfabricated pumps, by electro-kinetic pumping,
by capillary-force based pumping, by other pumping means or by
other means of pressurization. Further, valves may be provided for
controlling the flowrate of the first or second fluid. Such valves
may be located within external connections, in the fluid container,
in the connections between the fluid container and the aperture or
in the aperture. Such valves may be closed or opened on demand.
[0034] The present device, as described herein, may be part of a
fluidic network. In such a fluidic network, there may be a feedback
system for measuring the network pressure, for example, the
pressure at the apertures and/or at the fluid containers.
Alternatively, feedback may be provided based on the volume of
fluid pumped. The feedback facilitates fluid flow control to avoid
undesired spreading of fluid on the surface. When a plurality of
fluid containers are present, each coupled to an aperture, pressure
may be controlled in each fluid container, either in parallel or
individually. Further, one or more valves may control the flow for
each fluid container, either in parallel or individually (e.g.,
through use of a flow controller).
[0035] The flow controller may apply a pressure for retaining the
fluid when the aperture is remote from the surface. The flow
controller may also comprise a capillary network for applying
pressure to the fluid. This capillary network may comprise one or
more parallel capillary members, a mesh, a porous material and a
fibrous material. There may be a plurality of fluid containers each
coupled to an aperture. The pressures applied may be such that the
fluid is drawn towards the fluid containers in response to
withdrawal of the aperture from the surface. There may be a
plurality of first and second fluid containers, each coupled to the
aperture, wherein the pressure is controlled in each fluid
container, either in parallel or individually.
[0036] The pressure for the first fluid container may be regulated
such that the first fluid is retained in the first aperture when
the flow path is remote from the surface. Pressure for the second
fluid container may also be regulated such that the difference
between the first and second pressures is oriented to promote flow
of the first fluid from the first fluid container to the second
fluid container, via the flow path, when the flow path is located
proximal to the surface (the first fluid in the device contacting
the surface). The first and second pressures can further be
regulated such that excessive fluid is drawn towards at least the
second fluid container in response to withdrawal of the flow path
from the surface. There may be a plurality of first fluid
containers each coupled to the flow path. Similarly, there may be a
plurality of second fluid containers each coupled to the flow
path.
[0037] As described above, the pressure in the first and second
aperture may be generated by, e.g., external pumps. A feedback
system may be provided that measures the pressure within the
system, for example at the first and second aperture and/or at the
first and second fluid container. The feedback system may be based
on the volume of fluid pumped in the first and second fluid
container. Employing this feedback system can facilitate control of
the fluid flow and prevention of undesired spreading of fluid on
the surface. There may be a plurality of first and second fluid
containers each coupled to first and second apertures, where
pressure is controlled in each of the first and second apertures,
either in parallel or individually. Further, there may be one or
more valves, controlling flow for each of the first and second
apertures either in parallel or individually. There also may be a
plurality of first fluid containers each coupled to the flow path
and/or a plurality of second fluid containers each coupled to the
flow path.
[0038] In an exemplary embodiment of the present invention, the
first flow controller applies a first pressure for retaining the
fluid when the flow path is remote from the surface. The second
flow controller applies a second pressure to the second fluid such
that the difference between the first and second pressures is
oriented to promote flow of the first fluid from the first fluid
container to the second fluid container via the flow path, in
response to the flow path being located proximal to the surface and
the fluid in the device contacting the surface. Many other
applications of the present invention are possible.
[0039] As mentioned above, the device may comprise a unitary
construction, and may be formed from materials that include, but
are not limited to, elastomer, silicon, SU-8, photoresist,
thermoplastic, ceramic, metal, and combinations comprising at least
one of the foregoing materials. Alternatively, the device may
comprise a layered construction, with each layer formed from
materials that include, but are not limited to, glass, polymer,
silicon, SU-8, photoresist, thermoplastic, metal, ceramics and
combinations comprising at least one of the foregoing
materials.
[0040] As mentioned above, the present devices are particularly
useful for transporting a first fluid from a fluid container, well,
reservoir, or similar fluid container, to a surface, and to confine
the first fluid on the surface without the need for a physical seal
between the device and the surface. Accordingly, each aperture of
the device may be defined by and comprise non-sealing materials,
including, but not limited to, silicon. The non-contact operation
of the present device prevents contamination and/or damage to the
surface being treated and/or to the device.
[0041] The present treatment techniques are applicable to surfaces
having a wide range of different properties and wettability. The
present device permits addition of a flow of first fluid, thus
preventing depletion of material adsorbed to the surface treated.
Homogeneous patterns of, for example, biomolecules may be thereby
produced. When the present device is traced over the surface to be
treated, the lines produced are smoother and smaller than those
attained using conventional techniques, such as ink jet printing.
For example, if the amount of the first fluid deposited is
relatively small, there is little if any no spreading, quick drying
and no excessive accumulation of material on the surface.
[0042] According to the present techniques, the concentration of
deposited materials may be varied as the device is drawn over the
surface treated. A range of gradients in concentration of deposited
materials may thus be produced. Therefore, such a device is useful
for both additive and subtractive patterning of materials onto a
surface. Further, a series of such devices may be drawn over a
surface in sequence. Each aperture of such a series of devices may
contain a different one of a potential group of reagents for
collectively implementing a chain reaction on the surface.
[0043] According to the teachings of the present invention, the
device(s) can be pre-filled with processing fluids for subsequent
repetitive application and surface removal during processing.
Surface processing can be repeated multiple times using the same
device without refilling (which can delay the process). The present
device can also be swiftly mass-produced via conventional
microfabrication techniques. In typical applications, the present
device can be placed at an arbitrary location on a surface and
process parameters can be controlled via dimensions and contact
time. Arrays of such devices are relatively easy to fabricate.
[0044] The present devices are suitable for treating curved
surfaces, such as beads or cylinders, inhomogeneous surfaces,
surface with variable wettability, corrugated or otherwise
roughened surfaces and the like. Further, the present device may be
employed to deposit biomolecules in selected regions of a surface,
e.g., to make bio-arrays, thus facilitating mass fabrication of
bio-chips. The present device may also be employed in subjecting
selected areas of a surface to other processes, including, but not
limited to, processes for repairing pattern defects on a surface,
etching specific areas of a surface, depositing metal on a surface,
localizing an electrochemical reactions on a surface, depositing
catalytic particles for electroless deposition of metals,
deposition glass or latex beads or other particles on a surface,
passivating specific areas of a surface, patterning proteins,
deoxyribonucleic acid (DNA), cells, or other biological entities on
a surface, making assays and staining cells.
[0045] The present device may be operated facing upwardly towards a
downward facing surface, especially when the dimensions of the
device are chosen to be small, such that forces in the fluid
interface exceed inertial forces. In general, gravity has a limited
effect on the device such that use of the device in reduced gravity
environments is possible.
[0046] In one aspect of the present invention, a two aperture
applicator head is located proximal to the surface. A first fluid
is supplied to the surface via the applicator head. The applicator
head is then retracted from the surface.
[0047] During supplying the first fluid, the first fluid flows from
the first fluid container to the second fluid container via the
flow path. The flow of the first fluid from the first fluid
container to the second fluid container may be varied during the
supply of the first fluid to the surface. Prior to retracting the
applicator head, the applicator head may be moved relative to the
surface, with the first fluid in one or more of the apertures
contacting the surface.
[0048] The applicator head may be oriented relative to the surface
such that traces of the fluid produced as the applicator head is
moved relative to the surface remain separate, or alternatively,
overlap. Prior to locating the applicator head proximal to the
surface, the same fluid may be loaded into each of the fluid
containers. Alternatively, one or more different fluids may be
loaded into one or more of the fluid containers.
[0049] Further disclosed herein is a method for applying a fluid to
a surface comprising the following steps. An array of applicator
heads is located proximal to the surface. A first fluid is supplied
to the surface via the array. In each applicator head of the array,
the first fluid is flowed from the first fluid container to the
second fluid container via a flow path. The array is moved relative
to the surface with the first fluid in each aperture contacting the
surface. The array is then retracted from the surface.
[0050] In at least one applicator head of the array, the flow of
the first fluid from the first fluid container to the second fluid
container may be varied during the supply of the first fluid to the
surface. The array may be oriented relative to the surface in a way
such that traces of the flows of first fluid produced as the array
is moved relative to the surface remain separate, or alternatively,
overlap. Similar or different first fluids may be loaded into each
applicator head of the array.
[0051] In one embodiment of the present invention, an applicator
head is brought close to a surface so as to contact the surface
with the fluid in an area of micrometer dimensions defined by the
geometry of the aperture. The applicator head is then removed from
the surface. Prior to the removal of the applicator head, the
surface may be moved laterally relative to the applicator head with
the first fluid in the applicator head remaining in contact within
the surface so that the first fluid is traced across the surface.
Alternatively, the tracing may be performed using the applicator
head and having the first fluid flowing between the apertures as
the applicator head is traced is over of the surface.
[0052] A more complete understanding of the present invention, as
well as further features and advantages of the present invention,
will be obtained by reference to the following detailed description
and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a cross-sectional side view/functional diagram of
a fluid applicator with a concentrical arrangement of conduits;
[0054] FIG. 2a is across-sectional view of an applicator head with
a first conduit arranged at a distance from a second conduit;
[0055] FIG. 2b is a plan view of the bottom surface of the
applicator head shown in FIG. 2a;
[0056] FIG. 3 is a plan view of the bottom surface of an applicator
head with more than two conduits;
[0057] FIG. 4 is a cross-sectional view/downside view of an
applicator head with two apertures within an arc-shaped recess;
[0058] FIG. 5 is a plan view of the device shown in FIG. 3
operating in a drawing mode;
[0059] FIG. 6 is a plan view of a surface treated by the drawing
operation shown in FIG. 5;
[0060] FIG. 7 is a plan view of a multi-path device operating in a
drawing mode; and
[0061] FIG. 8 is a plan view of a surface treated by the drawing
operation shown in FIG. 7.
[0062] All the figures are for sake of clarity not shown in real
dimensions, nor are the relations between the dimensions shown in a
realistic scale.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0063] Referring first to FIG. 1, a substrate having an upper
surface 11, carries on surface 11 a fence 21 that surrounds a space
filled with an environmental fluid 20. A fluid applicator comprises
a first fluid container 9 that is connected via a first flow
controller 7 to a first conduit 1 having a first aperture 18
arranged in proximity to the surface 11. A second fluid container
10 is connected via a second flow controller 8 to a second conduit
2 having a second aperture 19 arranged in proximity to the surface
11, and surrounding said first aperture 18. The second fluid
container 10 is connected via a filter 13 to the first fluid
container 9. The first fluid container 9 holds a first fluid 3 that
is movable through the first conduit 1 towards the first aperture
18, and from there directable towards the surface 11. The second
aperture 19 provides a flow of a second fluid 4 away from the
surface 11 through the second conduit 2 into the second fluid
container 10.
[0064] This arrangement allows for the creation of a fluid flow out
from the first conduit 1 alongside the surface 11 and into the
second conduit 2. This arrangement can be used to modify the
surface 11, for instance by selecting as the first fluid 3 an acid
that etches the surface where the acid impinges onto the surface
11, thereby creating an etched pattern 12. The second fluid 4 will
be composed of a part of the first fluid 3 and of the environmental
fluid 20.
[0065] The first flow controller 7 and the second flow controller 8
are functional to control the speed of flow through the
corresponding conduits 1, 2. The filter 13 may be employed to
recover the first fluid 3 from the second fluid 4. The first flow
controller 7 is arranged for controlling a first flow rate and/or a
first pressure p3 of the first fluid 3. The second flow controller
8 is arranged for controlling a second flow rate and/or a second
pressure p4 of said second fluid 4.
[0066] Referring next to FIG. 2a, an applicator head 15 is
depicted, the applicator head 15 comprising a block of solid
material having two openings, one for the first fluid container 9
and one for the second fluid container 10. The first fluid
container 9 is again connected to a first conduit 1 through which a
first fluid 3 is deployable to a surface 11 for creating a pattern
12 thereon. The second fluid container 10 is again connected to a
second conduit 2 through which a second fluid 4 is movable into the
second fluid container 10 away from the surface 11. The end of the
first conduit 1 proximal to the surface 11 is the first aperture
18, while the end of the second conduit 2 proximal to the surface
11 is the second aperture 19. Both apertures 18 and 19 are arranged
at a distance d from each other. Thus, the first fluid 3 when
exiting from the first aperture 18 and when being drawn towards the
second aperture 19, moves along an elongated flow path between the
apertures 18 and 19.
[0067] The pattern that is created on the surface 11 corresponds to
the form of the flow path. Hence, with this applicator head 15,
patterns can be created that are not point-formed (as compared with
the results of the apparatus shown in FIG. 1). The flow rate of the
second fluid 4 can be controlled in a way that most, or even all,
of the first fluid 3 is dragged into the second aperture 19,
thereby reducing a blurring of the pattern through contact between
the surface 11 and the first fluid 3 at locations outside the
desired pattern area. The second aperture 19 can be designed to be
larger than the first aperture 18 to enhance this effect.
[0068] FIG. 2b shows a bottom view of this applicator head 15, also
depicting a possible form of the pattern 12 that may be created
therewith. The applicator head 15 is combinable with the
arrangement from FIG. 1, replacing the coaxial arrangement of
conduits. Hence, the applicator head 15 may be modified to comprise
also a first flow controller 7 and a second flow controller 8. The
applicator head 15 may also be modified to not comprise the first
fluid container 9 and the second fluid container 10, but instead be
connectable to the first fluid container 9 and the second fluid
container 10, e.g., as depicted in FIG. 1.
[0069] The first aperture 18 and the second aperture 19 of the
applicator head 15 can be brought close to the surface 11 immersed
in the environmental fluid 20, to be treated. The first flow
controller 7 is usable to dispense the first fluid 3 through the
first aperture 18 such that the first fluid 3 contacts the surface
11. Simultaneously, the second flow controller 8 can aspirate the
second fluid 4 at a second flow rate equal to or larger than the
first flow rate of the first flow controller 7. This can be
achieved by setting the first pressure p3 lower in absolute value
than the second pressure p4. The flow rates are preferably chosen
such that the first fluid 3 dispensed from the first aperture 18 is
aspirated back into the second aperture 19, with little or no
leakage or diffusion of the first fluid 3 into the bulk of the
environmental fluid 20.
[0070] It is advantageous to choose a dispense rate that results in
laminar flow (such flows being typical for small dimensions). With
laminar flow, there are less turbulences that could mix the
dispensed first fluid 3 with the surrounding environmental fluid 20
and thus can effectively prevent leakage of the first fluid 3. The
first fluid container 9 is loaded with the fluid 3 to be dispensed
onto the surface 11 to be treated.
[0071] The surface 11 may be a glass surface. However, the surface
11 may have other forms. For example, the surface 11 can be flat,
rough, corrugated, porous, fibrous, and/or chemically
inhomogeneous.
[0072] In operation, the first aperture 18 is brought proximal to
the surface 11. By tuning the first pressure in the first fluid
container 9, the first fluid 3 contacts the surface 11. Active flow
controllers such as external pumps, integrated pumps and valves may
be provided to regulate the pressure in the fluid container 9.
[0073] The supply of the first fluid 3 can be replenished as
necessary via the first fluid container 9. Such replenishing
permits repetitive reuse of the device. The first fluid container 9
may be loaded and/or unloaded with the first fluid 3 from below via
the first aperture 18. A lid may be provided to close the first
fluid container 9. The lid may be permanently sealed so that the
first fluid 3 can only be introduced via the first aperture 18. The
first aperture 18 may be likewise provided with a lid to prevent
evaporation, e.g., during periods of non-use. A support device
having a reservoir for the first fluid 3 may be provided for
filling, refilling and draining the first fluid container 9 without
involving removal of the lids.
[0074] The first fluid 3 may contain treatment agents for
processing a region of the surface 11. Engaging the device with the
surface 11 causes exposure of the region of the surface 11 facing
the first aperture 18 to the treatment agent. The treatment agent
may comprise molecules. The device is therefore useful in
bio-patterning applications. However, other applications are
possible, such as sequential delivery of different treatments to
the surface 11. Similarly, other fluid materials may be employed
depending on the surface processing desired. Examples of possible
fluid materials include, but are not limited to, etchants for
producing localized chemical reactions on the surface 11.
[0075] In FIG. 3, an arrangement of an applicator head 15
comprising more than two apertures is depicted. In this
arrangement, to a side of the flow path between the first aperture
18 and the second aperture 19 are arranged two additional apertures
21 and 22 each belonging to a third conduit 5. The third conduit 5
is here arranged to eject a third fluid 6 towards the surface 11,
thereby influencing the flow of the first fluid 3, as indicated by
the arrows in FIG. 3. The flow of the first fluid 3 may be narrowed
under the influence of the third fluid 6. Therefore, the third
fluid 6 serves as a forming fluid, giving the fluid flow of the
first fluid 3 a different form and hence with it also the resulting
pattern 12 on the surface 11.
[0076] At a side of the first aperture 18 distal from the second
aperture 19, another additional aperture 17 may be arranged, again
for ejecting the third fluid 6, using it as forming fluid to reduce
the flow of the first fluid 3 that is directed away from the second
aperture 19. At a side of the second aperture 19 distal from the
first aperture 18, a similar aperture 16 may be arranged. All
additional apertures, e.g., 16, 17, 21 and 22, that belong to the
third conduit 5 hence allow for the shaping of the fluid flow of
the first fluid 3 towards the second aperture 19, to improve the
pattern quality.
[0077] To further improve the pattern quality, the first aperture
18 and/or the second aperture 19 can be arranged in a recess 30, as
depicted in FIG. 4. The recess 30 then serves as a semi-open
channel to support the shape of the fluid flow of the first fluid
3. This configuration becomes particularly helpful if the recess 30
has a form that is not straight, e.g., is an arc. The first fluid 3
would follow a straight path if the recess 30 were absent, but the
recess 30 channels the first fluid 3 into its form allowing the
creation of a pattern that corresponds to the recess shape, e.g.,
the arc. The applicator head 15 may also comprise two distance
elements 17 that, in the event that the applicator head 15 is
brought into contact with the surface 11, determines the minimum
distance between the first aperture 18 and/or the second aperture
19 and the surface 11. The geometry that is present and functional
to shape the fluid flow along the flow path is thus determined and
fixed. This technique allows for the precise calculation of the
fluid flow and resulting pattern formation. The technique also
allows for use of the applicator head 15 repetitively wherein the
resulting pattern will be substantially identical on each use of
the applicator head 15.
[0078] The applicator head 15 can be of unitary construction which
makes it more stable, easier to manufacture and less prone to
damage. The applicator head 15 may be formed from elastomeric or
rigid materials. Such elastomeric or rigid materials can be shaped
by microfabrication techniques such as photolithography, etching,
injection molding and combinations comprising at least one of the
foregoing microfabrication techniques. Alternatively, the
applicator head 15 may be an assemblage of parts, such as a layered
assembly. Each layer may be formed from a different material, such
as, elastomer, silicon, SU-8, photoresist, thermoplastics, ceramic
and metal.
[0079] There may be multiple first conduits 1 or first apertures 18
coupled to a single second aperture 19 via a common flow path.
Different reactive agents may be introduced to each of the conduits
for reaction within the flow path. The flow path may thus act as a
reaction fluid container. Similarly, there may be multiple second
apertures 19 connected to a common first aperture 18 via a common
flow path. Further, there may be multiple first conduits 1 or first
apertures 18 connected to multiple second apertures 19 or second
conduits 2 via a common flow path.
[0080] Multiple devices, as described herein, may be integrated to
form an array. Multiple different configurations of such an array
are possible, involving different numbers of devices. The first
fluid containers 9 and the second fluid containers 10 of such
arrays may be interconnected to form a cascade. Some of the
interconnected fluid containers 9 and 10 may provide reaction fluid
containers in which the first fluid reacts. The product of such
reactions may be analyzed in other fluid containers or on the
surface 11. Such products may be used to treat or react with the
surface 11.
[0081] With reference to FIG. 5, the present device may be employed
to trace different fluids across the surface 11, each fluid being
loaded into a different fluid container of the device. The
applicator head 15 is therefore coupled to a drive 16, also
referred to as a manipulator. The manipulator 16 may be employed to
position the applicator head 15 relative to the surface 11. With
the drive 16, a series of patterns can be created one after the
other. A concatenated pattern can also be created when moving the
applicator head 15 during the patterning process, i.e., while the
first fluid 3 is flowing out of the first aperture 18. Therefore,
more complicated patterns can be created. The manipulator 16 may be
manually controlled or automatically controlled via a programmable
computer or similar electronic control system. The manipulator 16
may act on the applicator head 15 and/or the surface 11, providing
control of (either in plane and/or out of plane) translational
and/or rotational relative motions.
[0082] Referring to FIG. 6, depending the orientation and motion of
the applicator head 15 relative to the surface 11, the different
first fluids can be mixed in selected regions of the surface 11.
Such mixing may, for example, facilitate localized reactions
between the first fluids in selected regions of the surface 11.
Equally the applicator head 15 may be employed to trace similar
first fluids across the surface 11 in separate trails. Depending on
the orientation and motion of the applicator head 15 relative to
the surface 11, the trails can be separate or superimposed on each
other.
[0083] A plurality of applicator heads 15 may be grouped together
in an array. For example, such an array may comprise two first
apertures 18 extending from separate first fluid containers 9. Each
first fluid container 9 may contain the same fluid material or
different fluid materials. Other arrays may comprise more than two
apertures. Groups of such apertures may share a common fluid
container.
[0084] Referring to FIG. 7, two or more such applicator heads 15
may be mounted in an array and the applicator head 15 may be
employed trace a flow of the first fluid 3 across the surface 11.
Independent control of flow rate and tracing speed permits tuning
of the surface treatment applied via the applicator head 15. Such
an array may also be employed to trace two fluid flows across the
surface 11.
[0085] FIG. 8 depicts the resulting pattern 12 on the surface,
after use of the arrangement of FIG. 7. The fluid flows may
comprise the same or different fluid materials. Again, depending on
the orientation and motion of the applicator head 15 relative to
the surface 11, the trails of the fluid flows can be separate or
superimposed on each other. Independent control of the tracing
speed and flow rate permits creation of gradients in, for example,
adsorbed molecules on the surface.
[0086] In an exemplary embodiment, the flow path has the dimensions
of about 100 micrometers long and about 100 micrometers wide.
Likewise, the first apertures 18 may be about 100 micrometers wide.
The recess 30 may be between about one to about ten micrometers
deep. The volumes of the fluid containers 9 and 10 may be about 500
nanoliters each. However, it is to be appreciated that the
dimensions provided are merely exemplary and that different
dimensions are possible.
[0087] Given the present techniques, including the present
applicator head 15, it is possible to locally transport the first
fluid 3 from a reservoir, i.e., the first fluid container 9, to the
surface 11, and confine the first fluid 3 without requiring a
physical seal and without requiring a surface free-energy
confinement. Applicator head 15 can be used in different fluidic
environments, e.g., the surface 11 being immersed in the
environmental fluid which can be a liquid, a gas or a mixture
thereof. Thus, it is possible to use non-sealing materials such as
silicon to define the discharge aperture 18, without optimizing the
wettability of the apertures 18 and 19 and the applicator head
15.
[0088] The dispensed first fluid 3 is recoupable, e.g., can be
reused. First fluid 3 prevents contaminating or damaging the
treated surface 11 by a physical contact. The flow produced by the
applicator head 15 can prevent depletion of material that can
otherwise occur at these small scales. The localization of the
surface treatment may go down to areas of a few micrometers and
possibly even lower. This device permits the creation of arrays of
discharge/aspiration apertures at high density. When the applicator
head 15 is drawn over a surface, it can produce smooth lines, which
are smoother than inkjet patterns, and potentially smaller than
inkjet lines due to the fact that the first fluid 3 does not spread
significantly upon contacting the surface and because there is not
a large volume that dries.
[0089] If a flow is applied in conjunction with sliding, the
concentration of the deposited material can be continuously varied,
such as to produce gradients. Applicator head 15 can be used for
additive or subtractive (aspirator) patterning of the surface 11.
If a series of applicator heads 15 are drawn, one behind the other,
each discharge aperture, e.g., first aperture 18, can contain a
"chain-reaction" reagent. In another application, several discharge
apertures can be combined with a single aspirator, i.e., second
aperture 19, allowing for the performance of complex processes on a
region of a surface. For example, the several discharge apertures
may contain the four nucleotide bases present in DNA which could be
delivered in sequence, or the several discharge apertures may
contain two components that can react together, which could for
instance be used for joining, e.g., gluing, parts together.
Potential applications of the present techniques, include, but are
not limited to, patterning of organic materials, patterning of
biomaterials, locally exposing a sub-population of fragile cells to
a specific chemical treatment, exposing locally a sub-population of
beads to a specific chemical treatment and drawing lines on
surfaces in solution.
[0090] Fluid dispensed from the applicator head 15 is confined in a
volume defined by fluid flow. A physical seal between the
applicator head 15 and the surface, that is, the surface to be
contacted by the fluid, is not needed.
[0091] Applicator heads, such as applicator head 15, are useful in
the application of surface treatments in a range of fields,
including, but not limited to, microelectronics, optics, biology,
biochemistry and biotechnology. The present techniques also extend
to an array of such applicator heads 15.
[0092] There may be a feedback system for measuring pressure within
such a network, for example at the apertures 18 and 19 and/or fluid
containers 9 and 10. Alternatively, there may be provided feedback
based on the volume of fluid pumped. The feedback may facilitate
control of the flow of the first fluid and avoid undesirable
spreading of the first fluid on the surface. There may be a
plurality of fluid containers, each coupled to an aperture, where
the pressure is controlled in each fluid container, either in
parallel or individually. Further, there may be one or more valves
that control the flow for each fluid container in parallel or
individually.
[0093] The fluid container may apply a pressure for retaining the
fluid when the aperture is remote from the surface. The fluid
container may comprise a capillary network for applying pressure to
the fluid. The capillary network may comprise at least one of a
plurality of parallel capillary members, a mesh, a porous material
and a fibrous material. There may be a plurality of fluid
containers each coupled to an aperture. The pressures may be such
that the fluid is drawn towards the fluid containers in response to
withdrawal of the aperture from the surface. There may be a
plurality of first and second fluid containers, each coupled to the
aperture, where the pressure is controlled in each fluid container,
either in parallel or individually.
[0094] According to another exemplary embodiment of the present
invention, a method for applying a fluid to a surface is provided.
The method comprises the steps of locating a single aperture device
proximal to the surface, supplying the fluid to the surface via the
applicator head 15 and retracting the applicator head 15 from the
surface.
[0095] Applicator heads, such as applicator head 15, embodying the
present invention may be employed to deposit biomolecules in
selected regions of a surface to make bio-arrays, thus facilitating
mass fabrication of bio-chips. Applicator heads 15 embodying the
present invention can be equally employed in subjecting selected
areas of a surface to other processes, including, but not limited
to, processes for repairing pattern defects on a surface, etching
specific areas of a surface, depositing metal on a surface,
localizing an electrochemical reactions on a surface, depositing
catalytic particles for electroless deposition of metals,
deposition glass or latex beads or other particles on a surface;
passivating specific areas of a surface, patterning proteins, DNA,
cells, or other biological entities on a surface, making assays and
staining cells.
[0096] Applicator head 15 comprises a dual conduit system. The
apertures 18 and 19 of the conduits 1 and 2 are disposed at a
distance d from another, that is preferably larger than the
diameter of the apertures 18 and 19 themselves. The first fluid 3
that is delivered from the delivery aperture 18 travels along the
distance d and is then drawn up into the second aperture 19. The
device hence works as a dynamic fluid delivery system, in that the
first fluid 3 is always in motion to confine its spreading into the
environmental fluid 20. Due to the constant flow of the first fluid
3, the applicator head 15 can be moved over the surface 11 also
during the application of the first fluid 3. The major part of the
first fluid 3 that is expelled from the first aperture 18 onto the
substrate surface 11 is drawn into the second aperture 19. In the
ideal case, the portion of the first fluid that is drawn into the
second aperture 19 is more than 90 percent of the expelled amount
of the first fluid 3. The distance d between the apertures 18 and
19 determines the size of the resulting pattern 12 on the surface
11. In an application where the applicator head 15 is not moved
during the fluid application, the pattern 12 has hence a length
that substantially corresponds to the distance d. More precisely,
if the distance is measured between the centers of the apertures,
the length of the pattern 12 in that direction corresponds to the
distance d plus the distance between the centers and the distal
aperture rim of each of the apertures 18 and 19. In a case in which
the applicator head 15 is moved and used, for example, like a
writing implement in a "pencil-like" fashion, the distance d
determines the width of the line if moved orthogonally to the line
connecting the two apertures 18 and 19.
[0097] The expulsion of the first fluid 3 from the first aperture
18 occurs synchronously to the sucking of the second fluid 4 into
the second aperture 19, in order to achieve the desired precision
of the resulting pattern 12. To ensure that the fluid flow of the
second fluid 4 occurs at the same time as the fluid flow of the
first fluid 3, the flow controllers 7 and 8 can be coupled to
respond to a single switch-on signal, or be mechanically coupled.
The applicator head 15 is ideally operated to draw as much as
possible, if not all, of the expelled first fluid 3 into the second
aperture 19.
[0098] The device can also be operated to manipulate a particle,
such as a cell, a bead, a molecule or a nanodevice. Therefore, the
applicator head 15 is located near the particle that resides on the
surface 11 in the environmental fluid 20. The first fluid 3 is then
moved towards the surface 11, whereby the particle is removed from
the surface 11 and drawn into the second conduit 2. The applicator
head 15 can thereafter be removed from that position. The particle
can in the same, or a modified form, thereafter be deposited at a
different location, either by moving it into the first conduit 1
and from there to the different location, or by reversing the
operation of the applicator head 15 and moving the second fluid
towards the surface 11.
[0099] Although illustrative embodiments of the present invention
have been described herein, it is to be understood that the
invention is not limited to those precise embodiments, and that
various other changes and modifications may be made by one skilled
in the art without departing from the scope or spirit of the
invention.
* * * * *