U.S. patent application number 14/563180 was filed with the patent office on 2015-04-02 for nozzle device and nozzle for atomisation and/or filtration and methods for using the same.
This patent application is currently assigned to AQUAMARIJN HOLDING B.V.. The applicant listed for this patent is AQUAMARIJN HOLDING B.V.. Invention is credited to Wietze Nijdam, Cornelis Johannes Maria van Rijn.
Application Number | 20150093486 14/563180 |
Document ID | / |
Family ID | 19771962 |
Filed Date | 2015-04-02 |
United States Patent
Application |
20150093486 |
Kind Code |
A1 |
van Rijn; Cornelis Johannes Maria ;
et al. |
April 2, 2015 |
Nozzle Device And Nozzle For Atomisation And/Or Filtration And
Methods For Using The Same
Abstract
Nozzle device and nozzle for atomisation and/or filtration as
well as methods for using the same. The present invention relates
to a nozzle and nozzle device for atomisation, in particular a
micro-machined reinforced nozzle plate, that may produce small
liquid droplets in air (spray) or into a liquid (emulsion) with a
narrow droplet size distribution and to make small air bubbles into
a liquid (foam) and to methods of making the same. The invention is
further related to a nozzle part for filtration as well as means
and methods to facilitate atomisation and filtration.
Inventors: |
van Rijn; Cornelis Johannes
Maria; (Hengelo, NL) ; Nijdam; Wietze;
(Apeldoom, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AQUAMARIJN HOLDING B.V. |
Hengelo |
|
NL |
|
|
Assignee: |
AQUAMARIJN HOLDING B.V.
Hengelo
NL
|
Family ID: |
19771962 |
Appl. No.: |
14/563180 |
Filed: |
December 8, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13448048 |
Apr 16, 2012 |
8936160 |
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14563180 |
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12073387 |
Mar 5, 2008 |
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13448048 |
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11101391 |
Apr 8, 2005 |
7963466 |
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12073387 |
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10362751 |
Feb 26, 2003 |
7138084 |
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PCT/NL2001/000630 |
Aug 28, 2001 |
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11101391 |
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Current U.S.
Class: |
426/474 ;
210/184; 210/490; 210/495; 210/499; 210/94; 426/490; 426/491 |
Current CPC
Class: |
B05B 17/0646 20130101;
B01F 3/20 20130101; B05B 1/02 20130101; B01F 2215/0068 20130101;
B01D 67/0034 20130101; B01D 2321/2066 20130101; B01D 65/02
20130101; B01F 3/2057 20130101; B01D 71/64 20130101; B05B 15/40
20180201; B01D 63/08 20130101; B01D 61/18 20130101; B01F 13/0066
20130101; B01D 69/02 20130101; B01D 63/16 20130101; B01D 71/02
20130101; B01D 67/003 20130101; B01D 2321/185 20130101; B01D
67/0088 20130101; B01F 13/0062 20130101; B01F 13/0059 20130101;
B01L 3/0241 20130101; C12H 1/16 20130101; B01F 3/04446 20130101;
B01D 2323/36 20130101; B01D 67/0093 20130101; B01F 2215/0006
20130101; B01F 3/0807 20130101; A01J 11/06 20130101; B01D 35/02
20130101; A23C 9/1524 20130101; B01D 2321/2075 20130101; A61M 15/00
20130101; B01D 35/28 20130101; B01F 3/04113 20130101; B05B 1/14
20130101; B01D 2323/38 20130101; B01L 3/5025 20130101; B01D 2321/04
20130101; B01D 71/022 20130101 |
Class at
Publication: |
426/474 ;
210/499; 210/490; 210/495; 210/94; 210/184; 426/490; 426/491 |
International
Class: |
B05B 1/14 20060101
B05B001/14; C12H 1/16 20060101 C12H001/16; B01D 35/02 20060101
B01D035/02; A23C 9/152 20060101 A23C009/152; B01F 3/04 20060101
B01F003/04; B01D 35/28 20060101 B01D035/28; A01J 11/06 20060101
A01J011/06 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2000 |
NL |
1016030 |
Claims
1. Filtration device for filtration of a fluid, comprising a
functional plate which is provided at a first main surface of a
support body, the functional plate comprising at least one orifice
and the support body comprising a cavity in fluid communication
with said at least one orifice, wherein said functional plate has a
thickness of less than 2 micron at the area of said cavity and
wherein said at least one orifice in said functional plate has a
length which is less than six times a diameter thereof, and in
particular is shorter than said diameter and wherein said
functional plate comprises a number of orifices which share said
cavity in common and are jointly in fluid communication with said
cavity and wherein said orifices are arranged closely together into
a group of orifices and wherein said at least one orifice in said
functional plate has a diameter less than 10 micron.
2. The filtration device of claim 1 wherein said support body
comprises a silicon substrate and wherein said functional plate
comprises a separate layer provided on said substrate.
3. The filtration device of claim 1 wherein the functional plate is
provided with an immune binding or Elisa coupling agent.
4. The filtration device of claim 1 wherein a mutual spacing
between an orifice and an adjacent orifice is between three and
thirty times a diameter of said orifices.
5. The filtration device of claim 1 wherein said functional plate
comprises a zone along a boundary of said cavity which is
substantially free of any orifice and has a width which is at least
a number of times as large as a thickness of said functional
plate.
6. The filtration device of claim 1 wherein said functional plate
has a bare surface and wherein said orifice protrudes slightly out
of said bare surface of said functional plate.
7. The filtration device of claim 1 wherein, at said main surface,
said cavity has a cross-section with a width of less than 250
micron, particularly less than 100 micron.
8. The filtration device of claim 1 wherein said cross-section has
a length of more than 300 microns.
9. The filtration device of claim 1 wherein said silicon substrate
is formed from a <110> silicon wafer.
10. The filtration device of claim 1 wherein a glass substrate is
bonded to said functional plate and wherein said glass substrate
comprises at least one flow channel which is in open communication
with said cavity in said support body supporting said functional
plate.
11. The filtration device of claim 1 wherein said functional plate
is countersunk to a depth of between 10 and 500 micron in the ring
shaped support frame.
12. The filtration device of claim 1 wherein an optic transparent
cover plate is placed over the functional plate and wherein a flow
channel with a depth of 50 to 500 micron is present between the
functional plate and the cover plate.
13. The filtration device of claim 1 wherein said functional plate
comprises a number of substantially identical orifices which are
spaced apart over a mutual distance which is between 3 and 30
times, particularly between 3 and 10 times, their diameter.
14. The filtration device of claim 1 wherein functional plate is
provided with a metallic layer facilitating optic non-transparency,
non-quenching, electrolysis or electric heating applications.
15. A method of filtering beer or milk by using the filtration
means of the type according to claim 1.
16. A method of foaming or emulsifying a first fluid by using a
functional plate which is provided at a first main surface of a
support body, the functional plate comprising at least one orifice
in fluid communication with a cavity in said support body, wherein
said functional plate has a thickness of less than 2 micron at the
area of said cavity in said support body, wherein said at least one
orifice in said functional plate has a length which is less than
six times a diameter thereof, and in particular is shorter than
said diameter, and wherein the functional plate is brought into
contact with a second fluid.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS:
[0001] This application is a division of co-pending application
Ser. No. 13/448,048, filed on Apr. 16, 2012, which is a divisional
of application Ser. No. 12/073,387, filed on Mar. 5, 2008, which is
a division of application Ser. No. 11/101,381, filed on Apr. 8,
2005, now U.S. Pat. No. 7,963,466, which is a division of
application Ser. No. 10/362,761, filed on Feb. 26, 2003, now
abandoned, which is the national phase of PCT International
Application No. filed as an application No. PCT/NL01/00630, filed
on Aug. 28, 2001 under 35 U.S.C. .sctn.371 which claims priority of
Netherlands Application No. 1016030, filed Aug. 28, 2000. The
entire contents of each of the above-identified applications are
hereby incorporated by reference.
BACKGROUND
[0002] The present invention relates to a nozzle device having a
nozzle for atomisation of a fluid, the nozzle comprising a nozzle
plate support body having a cavity extending from a first main
surface to a second main surface thereof, and comprising a nozzle
plate having at least one nozzle orifice in fluid communication
with said cavity at said first main surface side of said nozzle
plate support body. The invention further relates to nozzles as
used in such a nozzle device.
[0003] These devices are used for filtration purposes and or for
atomisation of a fluid to produce small liquid droplets in air
(spray) or into a liquid (emulsion) with a relatively narrow
droplet size distribution and to make small air bubbles into a
liquid (foam) and to methods of using the same. The device and
especially the nozzle plate may be produced by micro-machining
(Micro System Technology) which means that the subject nozzle part
means are produced using lithography steps related to semiconductor
fabrication methods. Alternatively spark erosion and laser drilling
technigues may be used, but in general these tend to be less
reproducible and less precise in comparison with micro-machining
methods.
[0004] The performance of many atomisation devices can be improved
if the atomising device provides very small droplets with a very
narrow pore size distribution.
[0005] For example, small droplets between 2 and 3 micron in
diameter improve the effectiveness of medical atomisers because of
the high (80%) deposition intake deep into the lungs. Also the
stability of an emulsion (o/w, w/o) is greatly improved if the
emulsion droplets are all of equal size. Besides that, the
structural and rheological properties of many foams in the dairy
industry can be improved by the use of very small air bubbles with
a narrow size distribution.
[0006] The disadvantage of many conventional atomising devices is
that they break bulk liquid or gas into relatively large droplets
through use of stirring or turbulence. By more input of energy the
large droplets will be broken up in smaller droplets. As the
droplets become smaller than 20-100 microns, they become harder to
break and secondary atomisation typically ceases. The droplet size
distribution is in most cases rather broad.
[0007] It is known from fuel injectors that nozzle structures may
be used for obtaining a very fine spray for combustion improvement.
Such small nozzle structures however are very sensitive for fouling
and unwanted leakage due to blocked nozzle orifices. For a high
throughput of equally sized droplets normally an array of identical
nozzles is used. However if one or more nozzle orifices becomes
blocked the size distribution will broaden. If a nozzle orifice
becomes smaller through partial blockage the droplets of this
orifice will also become smaller. Moreover if the blockage is very
severe spraying(or jetting) will cease and liquid will flow through
this orifice over the surface of the nozzle structure hence
influencing or inhibiting spraying behaviour of the other
orifices.
[0008] It is also known that very small nozzles suffer from a
threshold pressure (Pascal pressure/capillary forces) before they
start spraying. The threshold pressure is inversely proportional to
the nozzle diameter. For a nozzle with a diameter of 1 micron this
pressure is typical 1-3 bar. For an array of nozzles it is
therefore very important that all nozzles have an equal geometry
with narrow tolerances and that the threshold pressure is kept as
low as possible.
[0009] A high flow rate can be achieved by choosing the flow
resistance of each nozzle orifice as small as possible and/or by
increasing the pressure difference over the orifice during jetting.
Practically the jetting pressures are chosen to be fairly higher
than typical 5-10 bar. Such pressures will exert high forces on the
nozzle plate. The nozzle plate is therefore chosen fairly thick
(>4-5 micron) in order to withstand such forces. However a thick
nozzle plate implies a long orifice length and thus a high flow
resistance and subsequently a reduced flow rate.
SUMMARY OF THE INVENTION
[0010] It is inter alia an object of the invention to provide a
nozzle device and a nozzle of the type referred to in the opeing
paragraph in which these drawbacks have been counteracted at least
to an impressive exntend.
[0011] To this end a nozzle device as described in the opening
paragraph is according to the invention characterized in that said
support body is provided with filtration means which comprise a
filtration plate which is in fluid communication with said cavity
at said second main surface side of said nozzle plate support
body.
[0012] A further object of the present invention is to produce a
properly constructed nozzle plate for atomisation at operational
pressures smaller than 10 bar.
[0013] Another object of the present invention is to provide nozzle
plates that produce droplets typically with a mean diameter of 10
micron or smaller with a very narrow droplet distribution.
[0014] Yet another object of the present invention is to provide
nozzle plates for small handheld atomising devices with a
throughput nearly independent of the viscosity of the fluid (e.g.
medicine) and means to reproducible facilitate atomisation.
[0015] Yet another object of the present invention is to produce a
properly constructed nozzle plate (filtration membrane) for
filtration of small and large amounts of liquid or gas and means to
facilitate filtration with such a filtration membrane, which may be
used in combination with atomisation applications.
[0016] Yet another object of the invention is to provide nozzle
plates for large atomising devices capable of substantial
throughput of atomised liquid or gas.
[0017] Yet another object of the invention is to provide nozzle
plates with orifices with a reduced flow resistance that can
withstand high operational pressures.
[0018] Yet another object of the invention is to provide atomising
devices that are rather insensitive for microbiological fouling and
unwanted leakage due to blocked nozzle orifices.
[0019] Yet another object of the invention is to provide atomising
devices that are less sensitive for the Pascal threshold
pressure.
[0020] These and additional objects and advantages of the invention
will become apparent from the technical description which
follows.
[0021] It is to be understood that both the foregoing summary and
the following technical description are exemplary and explanatory
and are not restrictive of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a cross section of a nozzle device with a nozzle
plate and pre-filter for atomisation.
[0023] FIG. 2 is a cross section of a nozzle device with a nozzle
plate and pre-filter for atomisation, in which the nozzle plate and
the pre filter are deepened for protection.
[0024] FIG. 3 is a cross section of a nozzle device with a nozzle
plate and pre-filter for atomisation made from one piece.
[0025] FIG. 4 is a top view of a nozzle plate containing slits plus
special slits for pressure reduction.
[0026] FIG. 5A is a cross section of a nozzle device containing
more orifices to increase the throughput.
[0027] FIG. 5B is a cross section of a nozzle device containing
more orifices to increase the throughput with the possibility of
liquid flow on both sides of the membrane.
[0028] FIG. 6 is a top view of closely packed nozzle plates.
[0029] FIG. 7A is a top view of interconnected nozzle plates.
[0030] FIG. 7B is a cross section of interconnected nozzle
plates.
[0031] FIG. 8A is a cross section of a thick nozzle plate with
reduced flow resistance.
[0032] FIG. 8B is a cross section of a spiral nozzle orifice.
[0033] FIG. 8C is a cross section of the manufacturing method of a
spiral nozzle orifice.
[0034] FIG. 9 is a top view of nozzle plate with improved jetting
behaviour.
[0035] FIG. 10A is a top view of a substantially stronger nozzle
plate with slit type orifices.
[0036] FIG. 10B is a top view of a substantially stronger nozzle
plate with circular orifices.
[0037] FIG. 11 is a cross section of a nozzle device with a coated
nozzle plate.
[0038] FIG. 12 is a top view of a nozzle plate with separated
hydrophilic/hydrophobic membrane coating for improved jetting/jet
start.
[0039] FIG. 13 is a cross section of a nozzle plate with slightly
protruding nozzles.
[0040] FIG. 14 is a cross section of a nozzle plate with
hydrophilic/hydrophobic coatings around the orifices.
[0041] FIG. 15 is a cross section of a vibrating nozzle plate with
drain plate.
[0042] FIG. 16 is a cross section of nozzle plate, placed under an
angle, in a cross flow channel.
[0043] FIG. 17 is a top view of a nozzle plate with extra nozzles
for co-flow.
[0044] FIG. 18 is a cross section of a nozzle plate for
emulsification.
[0045] FIG. 19 is a cross section high performance filter with the
possibility for light to pass through.
[0046] FIG. 20 is a top view of a filter for analysing particles
that isolates the particles for enhanced recognition.
[0047] FIG. 21 is a top view of a plastic disc supporting a nozzle
plate for analysis purposes.
[0048] FIG. 22 is a cross section of a plastic disc supporting a
nozzle plate for analysis purposes plus funnel.
[0049] FIG. 23 is a cross section of a reusable nozzle plate with a
transparent cross flow channel.
[0050] FIG. 24 is a top view of a glass module plate for high
volume nozzle plates.
[0051] FIG. 25 is a cross section of a glass module plate for high
volume nozzle plates showing the shallow cross flow channels.
[0052] FIG. 26 is a cross section of a glass module plate for high
volume nozzle plates showing a channel of the comb structure.
[0053] FIG. 27A is a cross section of stacked module plates.
[0054] FIG. 27B is a opened 3D view of stacked module plates
showing the liquid flow within the stack.
[0055] FIG. 28 is cross section of a nozzle plate for evaporation
purposes.
TECHNICAL DESCRIPTION OF THE PREFERRRED EMBODIMENTS
[0056] A first embodiment of a nozzle device 1 is shown in FIG. 1.
The nozzle device 1 comprises a nozzle for atomisation 2, with a
nozzle plate 10 with at least one nozzle orifice 11 and a nozzle
plate support body 12 with a nozzle cavity 13, further comprising
filtration means 3 with a filtration plate 15 with at least one
filtration orifice 16 and a filtration plate support body 17 with
at least one filtration cavity 18. This nozzle device 1 is rather
insensitive for microbiological fouling and unwanted leakage due to
blocked nozzle orifices 11 because of the placement of a pre-filter
for the nozzle for atomisation 2. Basically the nozzle for
atomisation 1 and filtration means 2 are made with the same micro
machining techniques giving many additional advantages. The two
parts 2 and 3 may have similar size and flatness and can therefor
easily be directly bonded or glued 22 together without the need of
separate or elaborated connection parts, that may introduce
particle contamination between the nozzle plate 11 for atomisation
and filtration plate 15. A silicon wafer containing a number of
nozzles for atomisation and a silicon wafer with a number of
filtration means may be first bonded together before sawing the
wafer sandwich into separate dies with individual nozzle and
filtration means.
[0057] Another embodiment of a nozzle device 1 is shown in FIG. 2,
characterised in that the nozzle orifices 11, 16 are made in a
2-200 micron deepened region 19 of the nozzle plate 2,3 with
respect to the nozzle plate support body 12 and filtration plate
support body 17, herewith protecting the nozzle and/or filtration
means during manufacturing and assembly against scratches etc. With
preference the nozzle plate support body 12 and filtration plate
support body 17 are identical, FIG. 3, the cavities 13,18 are then
made by etching the support material directly through the nozzle
and filtration orifices 11,16. With this manufacturing process
there can not be any particle contamination between the filtration
plate 15 and the nozzle plate for atomisation 10. In some cases it
has been proven useful to make in the filtration means 3 one or
more filtration orifices substantially larger (1-3 micron) than the
other ones (0.2-0.8 micron) in order to reduce the Pascal pressure
or to facilitate the removal of etching material(gas).
Alternatively the filtration orifices 16 are slit-shaped to reduce
the Pascal pressure. A special embodiment of such a filtration
plate has a number of very long slit shaped filtration orificess 20
(e.g. with a length of 50-100 micron) near the edges of the
filtration plate. Depending on the width 21 of the filtration plate
15 (e.g. 100 micron) and the applied pressure (e.g. 1 bar) this
slit will open due to local bending of the filtration plate 15
(FIG. 4). Preferably the fluid resistance of the filtration plate
15 is minimal 3 times smaller than the fluid resistance of the
nozzle plate 10. By this the pressure across the nozzle device 1 is
effectively only used for atomisation.
[0058] Nozzles for atomisation 2 can be made with known micro
machining techniques. A mono crystalline silicon wafer 12 with
thickness 400 micron is provided with a Low Pressure Chemical
Vapour Deposition grown layer 10 of low stress silicon nitride with
a thickness of 1 micron. With a suitable mask a photo lacquer
pattern with 2 micron orifices at the front side of the wafer 12
and a similar pattern with 15 micron openings at the back side is
being exposed and developed. With the aid of anisotropic reactive
ion etching a nozzle orifice 11 with a diameter of 2 micron and a
length of 1 micron is made in the silicon nitride layer and with
use of dry and wet chemical KOH etching a cavity 13 with a diameter
of 15 micron and a length of 400 micron is made in the silicon
wafer 12.
[0059] The flow rate .PHI. of a medium or a liquid with viscosity
.eta. through an orifice (tube) with length L and diameter D for
viscous flow at a pressure difference AP is given by the law of
Poiseuille: .PHI..sub.Poiseuille=.pi.D.sup.4.DELTA.P/128 L.eta.. A
parabolic velocity pattern with a low velocity along the wall and a
high velocity in the middle of the tube will settle in case the
length of the tube L is larger than typical six times the diameter
D. The mean velocity v of the medium or liquid is always given by
v=4 .PHI./.pi.D.sup.2.
[0060] In case the length L is of the order of the diameter D the
law of Poiseuille will change to the law of Stokes:
.PHI..sub.Stokes=D.sup.3.DELTA.P/24 .eta.. The parabolic velocity
pattern will not be valid in this regime. Dagan et al., Chem. Eng.
Svi., 38 (1983) 583-596 have proposed an interpolation formula for
both regimes: .PHI..sub.Dagan=D.sup.3.DELTA.P/24 .eta. [1+16 L/3
.pi.D].sup.-1.
[0061] At large velocities v the viscous regime will not be valid
any more because another force/pressure is necessary for a kinetic
(inertial) contribution to accelerate the medium or fluid to a
velocity v. This pressure difference is given by
.DELTA.P.sub.kin=0.5 .rho.v.sup.2, with .rho. the mass density of
the fluid v (cf. Law of Bernoulli).
[0062] An important insight according to the invention is that the
total needed pressure .DELTA.P.sub.tot is the sum of the viscous
and the kinetic contribution:
.DELTA.P.sub.tot=.DELTA.P.sub.vis+.DELTA.P.sub.kin=6 .eta..pi.[D+16
L/3 .pi.].sup.-1 v+0.5 .rho.v.sup.2.
[0063] Typical for a waterbased fluid and for a thin orifice this
means:
.DELTA.P.sub.tot.apprxeq.18.000 D.sup.-1 v+500 v.sup.2
(L<D, .eta.=10.sup.-3 poise, .rho.=1000 kg/m .sup.3, D in
micron, v in m/s, .DELTA.P in Pascal). At a .DELTA.P.sub.kin of 4
bar (=4.times.10.sup.5 Pascal) the maximum jet velocity will be 28
m/s. .DELTA.P.sub.vis will be for this velocity 500.000 D.sup.-1.
In case D>2 micron than .DELTA.P.sub.vis<2.5 bar.
.DELTA.P.sub.tot is then 4+2.5=6.5 bar, less than the maximum of 10
bar. However in case L/D>2 then at D=2 micron the needed
pressure will surely exceed 10 bar.
[0064] Another important insight is that with a very thin orifice
(L.apprxeq.D.apprxeq.micron) both in the viscous and in the kinetic
regime all the fluid will leave the orifice as a jet with constant
velocity v (no parabolic velocity distribution). Especially the
kinetic energy of the jet will make that the jet will prolong its
track before it breaks up in small droplets, which is particularly
useful for Rayleigh break-up of the jet in droplets in air.
Rayleigh droplets have a typical droplet size 1.6 times the
diameter D of the out coming jet. The fabrication tolerance in the
diameter D of the nozzle orifice is an essential factor in
determining the amount of liquid (.DELTA.V=4 .pi.(1.6D/2).sup.3/3)
in a Rayleigh droplet. The United States FDA imposes a
repeatability of 20% for 90% of the droplets and 25% for the
remaining 10%. Only micro machining methods are capable of
producing orifices with a tolerance less than 3% (=variation in
.DELTA.V<10%). Also because micro machining is done in a sterile
and particle free Clean Room environment also the effect of fouling
of the nozzles due to particles and/or micro organisms is
avoided.
[0065] Another important insight according to the invention is that
for a very thin Orifice (L.apprxeq.D.apprxeq.micron) the flow rate
at relatively low pressures (3-10 bar) is mainly determined by the
kinetic contribution, which means that viscosity of the fluid
(medicine) has a minor role as long as L.apprxeq.D and
.eta.<10.sup.-2 poise. Jetting (e.g. Rayleigh break-up) with a
nozzle plate with a thickness less than 2 micron and orifices with
a diameter between 0.4 and 10 micron at a pressure in which the
contribution of the kinetic regime (0.5 .rho.v.sup.2.) is larger
than the contribution of the viscous regime (6 .eta..pi.[D+16L/3
.pi.].sup.-1.v) is therefore a very good method to deliver and dose
medicines nearly independent of the viscosity of the medicine.
[0066] Another important insight according to the invention is that
medicine (e.g. proteins and peptides) degradation is strongly
diminished if such thin orifices are used at relatively low jetting
pressures (<10 bar) with a minimum of shear in strength, time
and length of the medicine in passing such an orifice.
[0067] Using the law of Stokes and Poiseuille (or Dagan) it is
easily to calculate that the flow resistance of the 2 micron
orifice 11 is still 5-10 times higher than the flow resistance of
the cavity 13 with diameter 15 micron and length 400 micron. This
means that the pressure/flow characteristics of this structure are
still mainly determined by the 2 micron orifice.
[0068] In preference the thickness of the nozzle plate 10 for
atomisation is less than six times the diameter of the nozzle
orifice 11 and in preference less than one to two times the
diameter in order to prevent the built up of a parabolic velocity
distribution. The flow resistance may be further reduced through
the manufacturing of tapering orifices although it is well known
that the amount of tapering is very difficult to control precisely.
In case the nozzle plate 10 has a thickness less than 2 micron it
still has sufficient strength and it is not necessary to taper the
orifices.
[0069] Nozzles can be used for as well atomisation and filtration.
An embodiment of a nozzle with a nozzle orifice for atomisation or
filtration 4 is shown in FIG. 5A, 5B and top view FIG. 6. The
nozzle plate 40 comprises more nozzle orifices 41 placed next to
each other in order to increase the throughput. The nozzle plate 40
with a thickness of 1 micron of low stress silicon nitride has a
width of less than 250 micron 30 and a length of more than 300
micron 31. The maximum pressure strength of each nozzle plate 40 is
well above 10 bar. A nozzle plate 40 with a width of 100 micron has
a pressure strength well above 20 bar. A number of those nozzle
plates 40 are closely packed with a mean distance less than 100
micron offering a large effective nozzle plate area as seen in
topview FIG. 6.
[0070] The nozzle 4 comprises further at least one shallow flow
channel 44 connected to the nozzle plate 40 with a mean depth of
minimum 10 and of maximum 300 micron connected to the nozzle plate.
This depth 43 is dependent on the size and number of the nozzle
orifices 41 in the nozzle plate 40. The flow resistance of the flow
channel 44 in the nozzle plate support should be at least one to
ten times smaller than the flow resistance of the nozzle plate 40
itself. In case the total flow resistance of the nozzle plate
support as defined by regions 44 and 45 is one to five times the
flow resistance of the nozzle plate 40 a nice flow limitation has
been constructed in case the nozzle plate 40 would disrupt.
Alternatively two or more openings 46,47 can be provided in each
nozzle plate to promote fluid flow and the removal of particles and
air bubbles underneath the nozzle plate 40.
[0071] Cross-flow cleaning 90,91 on both sides of the nozzle plate
is enhanced by the interconnection 81 in one or more directions of
all nozzle plate support flow channels 44 (FIG. 7A,7B). Silicon
bars 92 between the nozzle plates 40 may be provided for enhanced
strength.
[0072] Subsequently the nozzle plate 50 may be chosen thicker than
a few micron with corresponding tapering orifices 51 in order to
reduce the flow resistance still further, shown in FIG. 8A. A good
measure is also to make spiral grooves 55 in the nozzle orifice 51
to give the medium a rotational motion when leaving the orifice 51,
shown in FIG. 8B. Anisotropic and directional etching techniques
with SF.sub.6 and O.sub.2 at low biasvoltage 10-40 eV make it
possible to make such grooves in e.g. a <100> silicon wafer.
The groove 55 will start at a defined rectangular orifice 52, the
groove will turn and will stop turning as defined by the
orientation of the <111> planes 56 shown in FIG. 8C.
[0073] With preference a number of nozzle orifices 61 are placed
very close together (FIG. 9), which improves flow rate, filtration
and kinetic jetting behaviour, e.g. 2 or more nozzle orifices with
a diameter of 2 micron may be separated with a mean distance less
than 0.5 micron 62.
[0074] Nozzle plates can be made substantially stronger (up to
250%) when the nearest distance 100 between all nozzle orifices and
the nozzle plate support is at least six times the thickness of the
nozzle plate FIG. 10A, 10B.The pressure strength of the nozzle
plate may be further increased with at least 50% when the orifices
are placed in a triangular or rectangular pattern 101 with respect
to a long side of the nozzle plate support. Preferential the
orifices are slit shaped and placed parallel along the width of the
nozzle plate support, FIG. 10B. An organic coating 104, in
particular a parylene coating on the nozzle plate may further
increase the pressure strength of the nozzle plate. Also a bacteria
killing surface modification 105 may be applied, for example a
silver coating, FIG. 11. A silicon nitride coating on the nozzle
plate and the nozzle plate support may also be provided to make the
whole structure inert for acid and caustic.
[0075] A next embodiment of a nozzle for atomisation is shown in
FIGS. 12,13 and 14. The nozzle plate 10 with a thickness of 1
micron comprises circular orifices with a diameter of 0.8 micron.
The distance between any of two orifices of the nozzle plate is
larger than five times 110 the nozzle diameter in order to prevent
recombination of droplets formed of nozzles next to each other.
FIG. 13 shows a cross section of a nozzle plate wherein the
orifices are slightly protruding out 130 of the surface (0.1-2
micron) of the nozzle plate 10. This measure is particular useful
if the nozzle plate is used for jetting of a spray or
emulsification because it prevents that the droplets will adhere to
the surface of the nozzle plate just next to the nozzle orifice,
resulting in to large droplet formation. In case of atomisation
(FIG. 14) it is particular useful to make a small area (e.g. 2-5
micron radius around the nozzle) hydrophobic 140 to prevent droplet
attachment/smearing and an unwanted increase of the jet diameter
(confinement of the jet). Preferential the next surrounding area
141 should be made hydrophilic in order to drain a too large formed
droplet that might inhibit jetting behaviour along the hydrophilic
coated part of the nozzle plate. Good results have been obtained
with a micro porous hydrophilic coating (PolyVinylPyrolidone/
PolyEtherSulphone) with a thickness of a few micron on area 141.
Alternatively capillary forces may be used to drain the droplet
through e.g. the provision of a drain channel 156 with a height of
e.g. 2 to 50 micron between the nozzle plate and an e.g. parallel
placed drain plate 155 with an orifice 154 larger (e.g. 5 micron)
than the jetting orifice (e.g. 1 micron), see FIG. 15. The jet will
normally first pass the jetting orifice and next the larger orifice
without fluid contact with the drain plate, but as soon as a
droplet is formed that touches the drain plate it will be drained
through the drain channel. A hydrophilic inner surface 142 of the
nozzles of the nozzle plate is a good measure in order to suppress
a large Pascal Pressure with at least 50%.
[0076] Jetting may be enhanced by using a piezoelectric actuator at
a frequency between 100 kHz and 3 Mhz. Jetting may also be enhanced
using the eigenresonance frequencies of the nozzle plate. This
frequency should match the value of the initial jet velocity
divided by two to two hundred times the diameter of the nozzle,
typically a value between 50 kHz en 5 MHz. The eigenresonance
frequency is mainly determined by the mass and a fortiori lateral
dimensions of the free hanging nozzle plate (typical
1.times.10.times.10 micron to 4.times.250.times.2000 micron), the
rigidity of and the tensile pre-stress in the nozzle plate (typical
10.sup.6to 10.sup.9 Pascal). A vibrating nozzle plate 150 is shown
in FIG. 15.
[0077] Measures to prevent droplet coalescence include: to charge
the droplets during droplet formation with an external voltage, or
by friction (tribocharging) of the fluid in the nozzle plate
device, or by friction of the droplets with the air. An electrical
connection (short-circuit) between the patient and the atomising
device may be necessary (patient serves as an earth electrode).
Further measures include placing the nozzle plate at an angle 160
between 10.degree. and 90.degree. in a cross flow channel 161,
particularly useful for Rayleigh break-up (FIG. 16) or co-flow of
air or another medium through separate nozzles orifices. Good
results have been obtained with a nozzle plate design (FIG. 17) in
which the nozzles for atomisation are lined up and the nozzles for
co-flow 170 are lined up perpendicular to the cross flow channel.
The nozzles for the liquid and the nozzles for the air have
separated 172 supply channels. For emulsification it is
particularly useful to place the nozzle plate in a dead-end
configuration in the channel, which channel 181 narrows
significantly at the downstream side. With relatively large nozzle
orifices it is then possible to make very small emulsion droplets
or gas bubbles (FIG. 18) at least 2-10 times smaller than the
diameter of the smallest nozzles 180. Double emulsions (o/w/o or
w/o/w) can advantageously be made with this device, because small
emulsion droplets can easily pass the larger orifices without
coalescense.
[0078] FIGS. 19 and 20 show an embodiment of a filter means or
nozzle for retaining particles. The nozzle plate support body is
made out of one silicon <110> wafer. With this type of
crystal orientation it is possible to make perpendicular openings
in the support by use of wet (KOH) etching. When the width between
two walls of the nozzle plate support body 191 is chosen small
(e.g. 20 micron) it is possible to make a high flow resistance in
the nozzle cavity. For filtration purposes it has proven to be
useful to make an open porosity higher than 30%, not only because
of the high flux, but also because it is then relatively easy to
back-flush the membrane to prevent irreversible fouling.
[0079] The nozzle plate may also be used for retaining and
subsequent microscopic observation 192 of these particles, e.g.
bacteria, yeast cells, blood cells, etc. Fluorescent dyes may be
used to simplify and identify specific species of the
micro-organisms on the filter. Silicon nitride and other inorganic
nozzle plate materials have the advantage in contrast to many
organic polymeric materials that there is virtually no
auto-fluorescence signal from the material itself. In some cases it
is convenient to place the nozzle orifices further apart, in order
to isolate the micro-organisms from each other for a more easy
recognition and enumeration.
[0080] Very useful nozzle plates for this purpose are characterised
in that the spacing 200 between the nozzle orifices is minimum
three and maximum thirty times the diameter of the nozzle
orifices.
[0081] Filter means or nozzles may be used for disposable
filtration applications, with preference small nozzle plates 220
(e.g. 5.times.5 mm) are embedded in a ring shaped support 221 (e.g.
ABS plastic discs) with outer dimension of e.g. 1.0, 2.5 and 5 cm
in diameter and ready to use in standardised commercial filtration
holders. With preference the nozzle plates are countersink 222 with
a depth of 10 to 500 micron in the ring shaped support to prevent
contamination, to facilitate packaging and mechanical rupture of
the nozzle plate (FIG. 22).
[0082] For reusable application an optic transparent cover slip 230
is placed over the nozzle plate in such a way that a cross-flow
channel 231 with a depth of 50 to 500 micron exists between the
nozzle plate and the cover plate (FIG. 23). With preference the
cover plate is a glass like material that is anodically bonded to
the nozzle plate or the nozzle plate support body at elevated
temperature (300-400.degree. C.) at a voltage between 500 and 1500
V. Cleaning and reuse of this device is facilitated 232 by using
ultrasound with a frequency between 100 kHz and 1 MHz. A liquid
handling board 234 can be made in glass (with a preferred thickness
between 0.5 and 11 mm) for supply of liquid to and from the nozzle
plate. By using an anodic bond between the nozzle plate or the
nozzle plate support body and the liquid handling board, glass can
be used as a liquid handling board for applications in which the
required pressures are higher than 0.8 bar.
[0083] With preference the nozzle plate support body has cavities
233 with at least the same size as the nozzle plate. It is then
possible to use a microscope 192 with a light source that projects
light 193 first through the nozzle support and next on the nozzle
plate. Most microscopes with phase contrast mode work in this
manner. FIG. 28 shows a nozzle plate 340 that can also be used for
the deposition (stencilling) 343 of isolated material spots 342 on
a substrate 341 with feature sizes determined by the lay out of the
nozzle plate. <110> silicon is a good support material for
the nozzle plate for these purposes.
[0084] Large nozzle plates with an outer circular diameter of e.g.
2, 3, 4, 6 and 8 inches may be used for micro filtration
applications like yeast cell filtration and clarification of beer
and other beverages. Sterile filtration of milk and other dairy
products is also possible with pore sizes between 5 and 0.22
micron. With a pore size of 0.8 micron it has been tested that a
log reduction of 5 to 6 of micro-organisms in milk is well
achievable in combination with back-pulse (pulsed permeate flow
reversal) technology. Typical flow rates are 1000-2000
l/m.sup.2/hour at low trans-membrane pressures (0.03-0.1 bar) with
a back-pulse rate of 0.01-5 Hz. The flow rate can be strongly
increased (4000-20.000 l/m.sup.2/hour) using ultrasound in a broad
frequency spectrum between 100 Hz-1 MHz. Preferably a frequency is
used under 15 kHz or above 50 kHz in order to suppress the
cavitation forces that might disrupt the nozzle plates between 15
kHz and 50 kHz. The ultrasound inhibits the forming of a dense cake
layer just before the nozzle plate. Alternatively the performance
for jetting, filtering, foaming and emulsification may be improved
by moving the nozzle plate tangential and/or orthogonal to the
fluid in contact with the nozzle plate with an actuator with an
amplitude of 0.1 to 100 micron and a frequency of 10 Hz-10 MHz.
[0085] In a special embodiment the nozzle plates or nozzle plate
support bodies are bonded to a glass plate in which flow channels
270,284 have been made with the use of grinding or powder blasting
(FIGS. 24, 25 and 26). Glass plates of type borosilicate have the
advantage that they are very flat, have nearly the same thermal
expansion coefficient 4.10.sup.-6.degree. C. as nozzle plates with
a silicon support. Anodic bonding results in a bond inert for acid,
caustic and oxydizing chemicals. The flow channels may be used for
permeate flow or alternatively for cross-flow. Preferably the flow
channels for cross-flow are placed in comb like structures which
taper in length and/or in height. The comb structure has the
advantage that the total pressure drop over the shallow channel
area 285, the comb teethes 270, the inlet 278 and outlet 279
(through the glass plate) can be kept low (less than 100 mBar),
while the cross flow speed at the nozzle plate surface (at the
shallow channel area 285) is yet high enough (more than 0.1 m/s)
for the enhancement of continuous removal of particles and yeast
cells during filtration. The distance 271 between the teethes 270
of each comb are preferably 0.5-5 cm, with a depth of 1-5 mm, a
width of 1-5 mm and a length depending on the outer circular
diameter. The tapering of the depth 274 is preferably 10 to 40 .
The width 273 is preferably tapering 10-40% per cm length of the
channel. In particular when powder blasting is used to manufacture
the channels in the glass plate, there is a triangular shape of the
channels with a relation of the width of the channel and the depth
if 1.2. The tapering is meant for a good redistribution of the
fluid from the incoming channel to the outgoing channel in such a
way that the pressure distribution along a single tooth of the
cross flow channels is homogeneous while the fluid velocity never
reaches zero to avoid hygienic failure. The pressure drop over
every single tooth is equal by varying the width and the depth of
the tooth. The mean cross flow height between the glass plate and
the nozzle plate 276 in the shallow channel area is preferably
between 0.1 and 1 mm As well the cross-flow side as the permeate
side may be bonded to a glass plate, also one glass plate may be
bonded on both sides with a nozzle plate device. With preference
the glass plate is being used for a filtration module, where a
larger filtration capacity is achieved by placing a number of
nozzle plate devices 301 with spacer structures 300, 302 in a stack
(plate and frame module with mirror placing of the glass plate 301
and the nozzle plates 303, FIG. 27A, 27B. The glass plate acts in
this module also as tubing for the cross flow inlet 281, 304, cross
flow outlet 282, 305 and permeate collection 280, 306, 307.
Furthermore, the glass plate may contain holes 283 for easy
positioning of the glass plate and the spacer structures.
Filtration characteristics may also be enhanced by using rotating
nozzle plates with respect to the medium in a module. A piezo
transducer for ultrasound can be placed on the back side (non
powder blasted side) of each glass plate. A typical longitudinal
resonance frequency of a glass plate with a thickness of 10 mm is
250 kHz. The ultrasound may be used either for enhancement of the
flow rate during filtration or for cleaning of the nozzle plates
after or during the filtration cycle. Of course cleaning after
filtration with ultrasound is accelerated using proper chemicals
(acid/caustic/enzymes etc.). Normal chemical cleaning procedures as
used for micro and ultra filtration membranes can herewith be
reduced from 1-2 hours back to 10 seconds-5 minutes. Cross-flow
cleaning on both sides of the nozzle plate is enhanced by the
interconnection in one or more directions of all nozzle support
openings.
[0086] Nozzle plates made with a silicon support can be made
chemically inert for caustic media by providing a thin LPCVD grown
silicon nitride coating with a typical thickness between 0.01 and 1
micron. Other organic and inorganic coatings like e.g.
Al.sub.2O.sub.3, TiO.sub.2, ZrO2, ZrO2/Si.sub.3N.sub.4 may be
applied to alter the Zeta potential and/or the wetting properties
of the nozzle plate to improve filtration characteristics. Other
coatings may also be applied to promote anti-fouling like
TiO.sub.2, PTFE, self assembling monolayers (SAM, e.g. based on
nitryls, disulfides or thiols) or long polymer chains (e.g.
polyethyleneglycol) coupled with an end- or side-group to the
nozzleplate. Dense sol/gel coatings or gas permeation layers like
Pd, PdAg may also be applied over and in the nozzle orifices to
make ultrafiltration and gas filtration membranes.
[0087] An important insight according to the invention is that the
combination of nozzle plates, back-pulse technology and ultrasound
has proven to be very powerful for the enhancement of flow rate and
the prevention of irreversible fouling. Without ultrasound a
typical clarification run for beer is 4-8 hours, with ultrasound
dosed at intervals of 10 minutes for a few seconds the run can be
extended to 4-8 days without the need of chemical cleaning
procedures.
[0088] Backpulsing for a very short time 10-50 ms at regular
intervals 0.01-5 Hz during cross-flow filtration at low
trans-membrane pressure will lift the cake layer from the nozzle
plate and will inject it higher in the cross flow channel where the
fluid velocity is sufficient high to take it further away.
[0089] Backpulsers are also very suitable to use for
up-concentration of samples for the detection and counting of food
spoiling or pathogenic micro-organisms, e.g. lacto bacillus, E-coli
and legionella. After the up-concentration all micro-organisms are
present on the nozzle plate and can be processed for e.g.
microscopic observation and PCR amplification. Small nozzle plates
of e.g. 4.times.4 mm can be put easily with a clean and sterile
pincer in a small PCR-cup. The nozzle plate can also be provided
with an immuno binding (or elisa coupling) agent for the selective
binding of certain species direct to the nozzle plate during
filtration, especially when cross-flow techniques are used for
up-concentration of the sample. Magnetic layers may also be
deposited for the attraction of immuno magnetic beads. Metallic
layers may also be provided on the nozzle plates for e.g. optic
non-transparancy, non quenching or electrolysis applications,
improvement of filtration under the applicance of a small voltage
difference between the fluid and the nozzle plate, or the
annihilation (electroporation) of microorganisms under the
applicance of a high voltage pulse. Platina may be deposited in
electrical resistor strips on the nozzle plate for heating
purposes. Also a bacteria killing surface modification may be
applied, for example a silver coating. Piezo materials may also be
applied for direct vibration of the nozzle plates or for the
detection of bending of the nozzle plates for pressure
registration. The intensity and the frequency of the backpulsers
may also be regulated by the registration of the nozzle plate trans
membrane pressure. The trans membrane pressure will normally
increase if there is a built up of a cake layer for the nozzle
plate.
[0090] Nozzle plates can be made in various ways according to the
invention.
A reinforced micromachined polymeric nozzle plate is made by [0091]
depositing a first layer of a photosensitive material, for example
negative resist polyimide (Durimide 7510) on a flat and smooth
substrate [0092] exposing the first layer to a suitable light
source through a mask (or a laser interference pattern) with a
nozzle pattern [0093] developing and if necessary curing the first
layer [0094] depositing a second layer of a photosensitive material
onto the first layer [0095] exposing the second layer to a suitable
light source through a mask with a nozzle support structure [0096]
developing and if necessary curing the second layer [0097]
releasing the thus obtained nozzle plate from the substrate
[0098] Another method of making a micromachined polymeric nozzle
plate, comprises the following steps [0099] depositing a first
layer of a photosensitive material on a flat and smooth substrate
[0100] exposing the first layer to a suitable light source through
a mask (or laser interference) with a nozzle pattern [0101]
developing the first layer [0102] etching anisotropically the
nozzle pattern to a certain depth, typically 1 to 5 micron, in the
substrate [0103] depositing a second layer of a photosensitive
material onto the substrate [0104] exposing the second layer to a
suitable light source through a mask with a nozzle support
structure [0105] developing the second layer [0106] etching
anisotropically the nozzle support structure to a certain depth,
typically 5 to 500 micron, in the substrate [0107] electroforming a
master mould from the substrate if necessary or using the substrate
itself as a master mould [0108] if necessary depositing a release
agent (teflon) on the master mould [0109] placing a thin sheet of
thermoplastic polymer with a typical thickness between 5 and 50
micron onto the master mould placing a second (flat) substrate with
a release agent on the polymeric sheet [0110] pressing the two
substrates to each other with a substantial load at a temperature
well above the glass transition temperature of the polymeric sheet
if necessary under reduced atmospheric conditions for a short
period [0111] releasing the thus formed polymeric nozzle plate from
the substrates at a temperature well below the glass transition
temperature
[0112] A reinforced micromachined electroformed nozzle plate is
made by [0113] depositing a conductive layer on a flat and smooth
electrically insulating substrate [0114] depositing a first layer
of a photosensitive material on the conductive layer [0115]
exposing the first layer to a suitable light source through a mask
with a nozzle support pattern [0116] developing the first layer
[0117] etching the conductive layer with a suitable chemical
etchant [0118] removing the first layer [0119] depositing a second
layer of a photosensitive material with a thickness of at least 2
micron onto the substrate [0120] exposing the second layer to a
suitable light source through a mask with a nozzle device [0121]
developing the second layer such that the remaining resist layer is
not in contact with the conductive layer [0122] putting the
substrate in a suitable electroforming bath using the conductive
layer as a cathode [0123] stopping the electroforming process as
soon as the electroformed layer has reached substantially at least
one or more parts of the remaining resist layer [0124] releasing
the thus electroformed nozzleplate
[0125] Another method of making a micromachined nozzle plate device
comprises the following steps [0126] depositing a first layer of a
photosensitive material on a flat and smooth substrate, said
substrate being covered at both sides with a thin membrane layer
[0127] exposing the first layer to a suitable light source through
a mask with a nozzle support pattern [0128] developing the first
layer [0129] etching the nozzle support pattern in the membrane
layer on one side of the substrate and further [0130] etching
chemically the nozzle support pattern through the substrate
stopping at a distance of 5 to 100 micron of the membrane layer at
the other side of the substrate [0131] depositing a second layer of
a photosensitive material onto the other membrane layer of the
substrate [0132] exposing the second layer to a suitable light
source through a mask (or laserinterference) with a nozzle plate
structure [0133] developing the second layer [0134] etching the
nozzle plate structure in the membrane layer [0135] etching through
the nozzles part of the nozzle support structure such that the
nearest distance between the nozzles and the nozzle support
structure is at least twice the nozzle diameter
[0136] Nozzle plates according to the invention may also be used
for the extrusion of very viscous media like macromolecular
solutions, gel-like solutions and protein-rich media, and for
microstructuring of food and pharmaceutical products like e.g.
synthetic meat (fibres). Nozzle plates according to the invention
may also used for micro-array and micro-titration applications, to
make double emulsions and to apply them in bio-capsules because of
the small diffusion length of the short nozzle orifice.
* * * * *