U.S. patent application number 11/407937 was filed with the patent office on 2006-08-24 for pyrotechnically actuated microvalve.
This patent application is currently assigned to COMMISSARIAT A L'ENERGIE ATOMIQUE. Invention is credited to Gilles Delapierre.
Application Number | 20060185728 11/407937 |
Document ID | / |
Family ID | 27763702 |
Filed Date | 2006-08-24 |
United States Patent
Application |
20060185728 |
Kind Code |
A1 |
Delapierre; Gilles |
August 24, 2006 |
PYROTECHNICALLY ACTUATED MICROVALVE
Abstract
The microvalve comprises a mini-piston moving due to the thrust
of gases given off by firing of a pyrotechnic charge and comprising
an aperture designed to enable communication to be established
between ends of microchannels of a microfluidic component. When the
ends between which communication is to be established open out onto
a face of a first planar substrate, the mini-piston is formed in a
second planar substrate, adjoined to the first, and comprises a
part that is mobile in translation or in rotation in the plane of
the second substrate. If a transverse slot is arranged between the
ends of the microchannels between which communication is to be
established, the mini-piston comprises a rod designed to slide in
the slot and the aperture is formed by a transverse orifice formed
in the rod of the mini-piston.
Inventors: |
Delapierre; Gilles;
(Seyssins, FR) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
COMMISSARIAT A L'ENERGIE
ATOMIQUE
PARIS
FR
|
Family ID: |
27763702 |
Appl. No.: |
11/407937 |
Filed: |
April 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10376622 |
Mar 3, 2003 |
7059339 |
|
|
11407937 |
Apr 21, 2006 |
|
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|
Current U.S.
Class: |
137/68.13 |
Current CPC
Class: |
F16K 99/0011 20130101;
Y10T 137/1647 20150401; Y10T 137/1624 20150401; Y10T 137/2224
20150401; F15B 15/19 20130101; F16K 2099/008 20130101; B81B 1/00
20130101; F16K 2099/0078 20130101; F16K 2099/0076 20130101; F16K
99/0001 20130101; F16K 99/0067 20130101 |
Class at
Publication: |
137/068.13 |
International
Class: |
F16K 17/14 20060101
F16K017/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 11, 2002 |
FR |
0203016 |
Claims
1. A microvalve for enabling or preventing communication of ends of
microchannels of a microfluidic component under a control of a
charge of pyrotechnic material, said micro-valve comprising: a
mini-piston moving due to a thrust of gases given off by firing a
pyrotechnic charge and comprising an aperture designed to achieve
said communication, wherein the microfluidic component
microchannels are achieved in a first planar substrate, the ends
between which communication is to be established open out onto a
face of said first planar surface, the mini-piston is formed in a
second planar substrate designed to be adjoined to the first planar
substrate and comprises a mobile part in the plane of the second
substrate, and the aperture is formed in the mobile part of the
mini-piston.
2. The microvalve according to claim 1, wherein the mobile part of
the mini-piston is mobile in translation in the plane of the second
substrate.
3. The microvalve according to claim 1, wherein the mobile part of
the mini-piston is mobile in rotation in the plane of the second
substrate.
4. The microvalve according to claim 1, wherein the mini-piston
comprises a deformable part integral with the mobile part,
deformation of the deformable part perpendicularly to the plane of
the second substrate in response to firing of the pyrotechnic
charge causing movement of the mobile part.
5. The microvalve according to claim 1, wherein the aperture is a
pass-through aperture.
6. The microvalve according to claim 1, wherein the aperture is a
blind aperture.
7. The microvalve according to claim 1, wherein the aperture is
substantially U-shaped.
Description
[0001] This is a Division of Application Ser. No. 10/376,622 filed
Mar. 3, 2003. The disclosure of the prior application is
incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a microvalve designed to enable or
prevent communication of ends of microchannels of a microfluidic
component under the control of a charge of pyrotechnic
material.
STATE OF THE ART
[0003] Biological analyses make use of a succession of elementary
biological reactions. Implementation thereof currently requires
several workstations corresponding to different elementary stages
of an analysis protocol. This involves a large number of handling
operations and consequently a non-negligible error factor, a
lengthy analysis time, a large consumption of reagents and samples,
and therefore a high cost per analysis.
[0004] To reduce costs and simplify implementation of such
analyses, it has been proposed to integrate all the stages of the
analysis protocol in a single microsystem. Microtechnologies make
it possible to achieve micropumps, microvalves, micromotors,
microfilters and mixers able to be integrated in a microfluidic
device comprising reaction chambers and/or microreservoirs
interconnected by a network of microchannels.
[0005] Microvalves can be used in a microfluidic component
comprising microchannels and/or microreservoirs and/or
microreactors to enable or prevent communication between the
different microchannels, microreservoirs or microreactors.
[0006] U.S. Pat. No. 6,168,948 describes a genetic analysis
microsystem, microlaboratory or DNA chip, integrating the whole
series of nucleic acid analysis steps on a surface the size of a
credit card. To manage fluid flows in the microchannels, this
microlaboratory essentially uses as microactuators microvalves
designed to open a channel in a preset step of the analysis. The
microactuators can also maintain a chamber in a vacuum and, under
the effect of an opening order, cause it to be filled with a fluid.
The microvalves, comprising a deformable membrane, can be actuated
by application of a vacuum or an external pressure,
electromagnetically, electrostatically or by coupling with a
piezo-electric microactuator.
[0007] The different types of known microvalves all present major
drawbacks for applications using microfluidic components
constituting microlaboratories or DNA chips. These single-use
components are in fact designed to be used at a patient's home, in
a doctor's surgery, on the site of an accident, etc. They therefore
have to be as compact as possible with an external control system
reduced to the strict minimum.
[0008] Furthermore, the document WO-A-9,822,719 and the
corresponding U.S. Pat. No. 6,247,485 describe a transdermal
medicine administration apparatus using three pyrotechnic
microactuators. Two of these microactuators are designed to break a
thin zone of a solid membrane to form orifices for passage of a
fluid, whereas the third microactuator is used to inflate an
envelope designed to expel the fluid through passage orifices
formed by the other two microactuators. This device is complex and
contact of the fluid with the pyrotechnic material is not
compatible with its use in an analysis microlaboratory in which any
pollution of a sample to be analyzed must be avoided.
[0009] It is also possible to use a membrane deformed by pressure
to blank off a microchannel formed in a substrate and in which a
fluid flows.
[0010] These different types of microactuators present the drawback
of not enabling both microchannel closing valves and opening valves
to be achieved. Yet both these functions are generally
indispensable in an analysis device. It can naturally be envisaged
to use two different types of microactuators on a single card to
achieve on the one hand closing microvalves and on the other hand
opening microvalves. Such a solution is however very complicated
and consequently very costly, without counting the compatibility
problems this would give rise to in the course of the different
manufacturing stages.
OBJECT OF THE INVENTION
[0011] The object of the invention is to overcome the drawbacks of
state-of-the-art microvalves and, more particularly, to enable
microvalves designed to be opened and microvalves designed to be
closed to be achieved with a single technique. The microvalves must
comprise reliable, low-consumption, inexpensive actuating means of
simple and rugged design, operational only when an analysis is
performed and able to tolerate storage for several years.
[0012] According to the invention, this object is achieved by the
fact that the microvalve comprises a mini-piston moving due to the
thrust of gases given off by firing of the pyrotechnic charge and
comprising an aperture designed to achieve said communication.
[0013] According to a development of the invention, the
microfluidic component microchannels are made in a planar substrate
comprising a transverse slot arranged between the ends between
which communication is to be established, the mini-piston
comprising a rod designed to slide in said slot, the aperture being
formed by a transverse orifice formed in the rod of the
mini-piston.
[0014] According to another development of the invention, [0015]
the micro-fluidic component microchannels are achieved in a first
planar substrate, [0016] the ends between which communication is to
be established open out onto a face of said first planar surface,
[0017] the mini-piston is formed in a second planar substrate
designed to be adjoined to the first planar substrate and comprises
a mobile part in the plane of the second substrate, [0018] the
aperture is formed in the mobile part of the mini-piston.
[0019] The mobile part of the mini-piston can then be mobile in
translation or in rotation in the plane of the second
substrate.
[0020] The mini-piston can also comprise a deformable part integral
with the mobile part, deformation of the deformable part
perpendicularly to the plane of the second substrate in response to
firing of the pyrotechnic charge causing movement of the mobile
part.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Other advantages and features will become more clearly
apparent from the following description of particular embodiments
of the invention given as non-restrictive examples only and
represented in the accompanying drawings in which:
[0022] FIGS. 1 and 2 schematically represent, in cross-section, a
microvalve according to the prior art respectively before and after
actuation.
[0023] FIGS. 3 and 4 schematically represent a device for filling a
reservoir in a transdermal medicine administration apparatus
according to the prior art respectively before and after
actuation.
[0024] FIG. 5 illustrates in cross-section a microfluidic component
comprising a first embodiment of two microvalves according to the
invention, one normally open and the other normally closed.
[0025] FIG. 6 illustrates an actuating stage able to be used with
microvalves according to the invention.
[0026] FIGS. 7 and 8 illustrate a particular embodiment of
mini-pistons of microvalves according to FIG. 5.
[0027] FIG. 9 represents a cross-sectional view along A-A of a
second embodiment of a microvalve according to the invention.
[0028] FIG. 10 represents the microvalve of FIG. 9 in cross-section
along B-B.
[0029] FIGS. 11 to 13 illustrate alternative embodiments of a
microvalve according to FIGS. 9 and 10.
[0030] FIG. 14 represents a cross-sectional view along C-C of a
third embodiment of a microvalve according to the invention.
[0031] FIG. 15 represents the microvalve of FIG. 14 in
cross-section along D-D.
DESCRIPTION OF PARTICULAR EMBODIMENTS
[0032] The microvalve according to FIGS. 1 and 2 is designed to be
used in a transdermal medicine administration apparatus
(WO-A-9,822,719 and the corresponding U.S. Pat. No. 6,247,485). It
comprises a substrate 1 made of semi-conducting material, for
example silicon, supporting an electrical resistor 2 the ends
whereof are connected to metal contacts 3a and 3b soldered onto
conducting tracks of a printed circuit 4. A charge 5 of combustible
material is arranged in the form of a thin film on the electrical
resistor 2 between the contacts 3a and 3b. The material of the
charge 5 is a pyrotechnic material for example of nitrocellulose
type. The substrate 1 comprises a truncated pyramidal crater so as
to form at its bottom part a thinner zone 7 adjoined to the
resistor 2 above the charge 5. A hole 8 is drilled in the printed
circuit 4 facing the thinner zone 7 of the substrate 1. The hole 8
is closed by a layer 9, for example of hydrogel, designed to be
charged with an active principle contained in a pocket (not shown)
communicating with the crater 6.
[0033] Current flow in the electrical resistor 2 causes heat to be
given off by Joule effect resulting in the pyrotechnic charge 5
being fired. This charge then gives off a sufficient quantity of
gas for the pressure to cause breaking of the thinner zone 7 of the
substrate 1 and of the part adjoining the resistor 2, forming
passages 10 (FIG. 2) for the gases to escape (dashed line arrows)
and for a liquid to pass (unbroken arrows) from the pocket
communicating with the crater 6, through the hole 8, to the layer
of hydrogel 9, which constitutes for example a reservoir of a
transdermal medicine administration apparatus.
[0034] A known transdermal medicine administration apparatus using
three microvalves equipped with pyrotechnic microactuators is
represented in FIGS. 3 and 4. A pocket 11 contains an ionic
solution designed to hydrate the hydrogel layer 9 when the three
microvalves are actuated by means of a printed circuit foil 4
arranged between the layer 9 and the pocket 11. A first microvalve
12 is fixed to the printed circuit foil 4, in central position, and
several microvalves 13 are arranged around the microvalve 12. An
inflatable envelope 14 housing the central microvalve 12 is pinched
against the printed circuit foil by the microvalves 13 and by the
pocket 11.
[0035] The microvalves 13 are of the type represented in FIGS. 1
and 2 whereas the microvalve 12 differs by the fact that it doesn't
comprise a hole 8. Firing of the combustible charges of the
microvalves 13 opens up passages 10 (FIG. 4) between the pocket 11
and the reservoir formed by the layer of hydrogel 9. Firing of the
combustible charge of the central microvalve 12 causes breaking of
the corresponding thinner zone 7 and the gases given off cause the
inflatable envelope 14 to inflate. This envelope then come and
occupies a large part of the internal volume of the pocket 11,
expelling the ionic solution contained in the pocket 11 through the
microvalves 13 and the associated passages 10 formed beforehand by
actuation of the microvalves 13.
[0036] This device is complex and contact of the fluid contained in
the pocket 11 with the pyrotechnic material, the combustion gases
of the pyrotechnic material and the debris of the thinner zone 7 of
the substrate 1 is not compatible with its use in an analysis
micro-laboratory in which any pollution of a sample to be analyzed
must be avoided.
[0037] The microfluidic component of FIG. 5 comprises a first
embodiment of two microvalves according to the invention, one
normally open and the other normally closed. The micro-fluidic
component is formed by superposition of three cards each formed by
at least one planar substrate and able to be fixedly secured by any
suitable means, for example by sticking. A first card 15 comprises
the microchannels 16 and/or microreservoirs and/or microreactors
constituting the microfluidic network of the component. It
comprises at least a first planar substrate, preferably made of
plastic material for example polymer, the microchannels being able
to be etched on the surface or on an additional substrate made of
plastic material, glass, silicon or quartz, added onto the plastic
substrate.
[0038] A second card 17 constitutes the valve card. In FIG. 5, it
is formed by a substrate wherein two microvalves are formed.
[0039] A third card 18 constitutes the actuator stage and comprises
a planar substrate, made of silicon, plastic material or glass, in
which cavities 19 are formed. A pyrotechnic charge 20 is arranged
in each of the cavities 19. Firing of a pyrotechnic charge is
performed by any suitable means, for example (FIG. 6) by means of a
resistor 21 arranged in each cavity 20 and supplied by two
associated conducting tracks 22a and 22b. A pyrotechnic charge 20
is deposited on each resistor 21, for example by screen printing or
by localized deposit by means of piezoelectric micropipettes. Each
pyrotechnic charge 20 can be fired independently by means of the
associated conducting tracks. The pyrotechnic charge firing control
circuit is preferably formed on the card 18.
[0040] As illustrated in FIG. 5, each pyrotechnic charge 20 is
arranged facing a microvalve of the second card 17. Firing of a
pyrotechnic charge causes gas to be given off and consequently
causes actuation of the associated microvalve.
[0041] A microvalve represented in FIG. 5 comprises a mini-piston
which moves perpendicularly to the plane of the valve card, upwards
in FIG. 5, under the thrust of the gases given off by firing of the
associated pyrotechnic charge 20. Each mini-piston comprises a base
23 (23a, 23b) and a rod 24 (24a, 24b). The base 23 is formed by a
zone of smaller thickness of the card 17 situated facing a cavity
19 containing a pyrotechnic charge 20. The base of a mini-piston
can have a constant thickness (base 23b) or comprise a zone of
smaller thickness on its periphery (base 23a) facilitating
deformation of the base under the thrust of the gases generated by
firing of the pyrotechnic charge 20. The rod 24 of a mini-piston is
substantially perpendicular to the base 23 and its free end moves
by sliding inside an associated transverse slot 25 (25a, 25b)
formed in the card 15. The rods 24 are preferably engaged slightly
by force in the corresponding slots 25, which enables tightness of
the mini-pistons to be achieved. A vent 38 is preferably situated
at the end of each slot 25.
[0042] Each rod 24 comprises an aperture formed by a transverse
orifice 26 (26a, 26b). Depending on the position of the transverse
orifice of the rod with respect to the ends of the microchannels
between which communication is to be established, the corresponding
microvalve is normally open or closed. Thus, in FIG. 5, a first
microvalve (23a, 24a, 26a) is normally open, its transverse orifice
26a being situated, in the corresponding slot 25a, at the level of
the opposite ends of the microchannels 16a and 16b between which
communication is to be established. The second microvalve (23b,
24b, 26b) is on the other hand normally closed, its transverse
orifice 26b being situated, in the corresponding slot 25b, below
the level of the opposite ends of the microchannels 16b and 16c
between which communication is to be established.
[0043] Firing of a pyrotechnic charge 20 causes a gas release
exerting a thrust on the associated mini-piston. The base 23 of the
mini-piston is then deformed and pushes the corresponding rod 24,
upwards in FIG. 5, into the corresponding slot 25. The pressure
provided by the gases given off by firing of the pyrotechnic charge
is sufficient to overcome the friction due to forced engagement of
the rod 24 in the slot 25. The first microvalve (23a, 24a, 26a)
closes after the corresponding charge 20 has been fired, the
transverse orifice 26a of its rod 24a then having moved upwards and
being located above the level of the opposite ends of the
microchannels 16a and 16b initially in communication. The second
microvalve (23b, 24b, 26b) on the other hand opens after the
corresponding charge 20 has been fired, the transverse orifice 26b
of its rod 24b then having moved upwards and being located at the
level of the opposite ends of the microchannels 16ba and 16c
between which communication is to be established.
[0044] The cavities 19 are preferably filled with a material, for
example resin, to enable a pressure to be exerted on the card 18
when the rods 24 are inserted in the slots 25.
[0045] As an example, the diameter of an orifice 26, corresponding
substantially to the diameter of the microchannels 16, is about
from a few tens to a few hundreds of micrometers and the width of
the base 23 of a mini-piston, corresponding substantially to the
width of a cavity 19, is about one millimeter.
[0046] Thus, the valve card 17 comprises microvalves designed to be
opened and microvalves designed to be closed which can be achieved
with one and the same technique. Customization of a microvalve (to
be opened or closed) is performed very easily in the course of
manufacturing simply by suitable positioning of the corresponding
transverse orifice 26.
[0047] The various elements constituting the valve card 17 can be
achieved by machining and/or by molding of the substrate. FIGS. 7
and 8 illustrate a preferred embodiment of the valve card 17. In a
first stage, a stack of flat layers 27 is made. In FIG. 7, the
stack comprises six layers 27a to 27f made of plastic material or
silicon. The stack of layers is then machined in the manner
represented in FIG. 8 to form the valve card 17 of FIG. 5. Thus,
the bases 23a and 23b of the mini-pistons are formed in the first,
thickest, layer 27a. The layers 27b and 27d form intermediate
layers of different thicknesses making it possible to situate
precisely, in the heightwise direction, the layers 27e and 27c in
which pass-through orifices are respectively formed, the width
whereof is greater than or equal to the width of the rod of a
mini-piston and respectively constituting, after the stack has been
machined, the orifices 26a and 26b of the rods 24a and 24b of the
mini-pistons. The top layer 27f of the stack constitutes the free
ends of the rods.
[0048] Such an embodiment is particularly simple. Only flat layers
are in fact molded and stacking thereof enables the position of the
orifices of the mini-piston rods to be defined precisely. In a
preferred embodiment, the rods 24 have a rectangular cross-section
as seen in top view.
[0049] A second embodiment of a microvalve according to the
invention is illustrated in FIGS. 9 and 10. As previously, the
microfluidic component comprises a first card 15 comprising the
microchannels 16 and/or microreservoirs and/or microreactors
constituting the microfluidic system of the component, a valve card
17 and a third card 18 constituting the actuating stage. In this
embodiment, the ends 28 of the microchannels 16 between which
communication is to be established open out onto the bottom face
(FIG. 9) of the planar substrate constituting the first card
15.
[0050] The valve card 17 comprises a mini-piston 29 able to move in
a recess 30 of the valve card 17, in the plane of the valve card,
i.e. perpendicularly to the ends 28 of the microchannels. In FIG.
10, the mini-piston 29 is joined to the periphery of the recess 30
by thin joining zones 31. A pyrotechnic charge 20 is arranged, in
the card 18 constituting the actuating stage, facing one end of the
recess 30, on the right of the mini-piston 29 in FIGS. 9 and 10.
Firing of the pyrotechnic charge causes release of the gas, the
pressure whereof is exerted on the mini-piston and causes movement
of the latter to the left in FIGS. 9 and 10, in the direction
indicated by the arrow 32, the joining zones 31 deforming to allow
this movement. The mini-piston comprises an aperture 33.
[0051] In FIGS. 9 and 10, the microvalve represented is normally
closed. The mini-piston 29 normally prevents any communication
between the ends 28a and 28b of the micro-channels between which
communication is to be established. The locations of the ends 28a
and 28b are represented in broken lines in FIG. 10. They are
arranged perpendicularly to the axis of movement of the mini-piston
29. When this piston is moved to the left after firing of the
pyrotechnic charge, the aperture 33 of oblong shape and
substantially perpendicular to the direction of movement of the
piston 29, then comes to face the two ends 28a and 28b and
establishes communication between the latter. A calibrated vent 34
is preferably provided in the card 17 to enable the gases to be
removed after the microvalve has been actuated. The vent 34 is
calibrated so that the overpressure generated very quickly after
firing of the pyrotechnic charge 20 is sufficient to move the
mini-piston 29 but then decreases quickly. The gases given off thus
do not have time to reach the channels containing the reagents. The
tightness between the actuating card 18 and the card 15 containing
the microchannels therefore does not have to be as high as in the
absence of a vent.
[0052] Various forms of mini-pistons and apertures can be
envisaged. In the alternative embodiment represented in FIG. 11,
the joining zones 31 are eliminated and the piston 29 is engaged
slightly by force in the recess 30. The locations of the ends 28a
and 28b can be substantially parallel to the direction of movement
of the mini-piston (arrow 32). In this case, the aperture 33 is
substantially parallel to the direction of movement of the piston.
In the particular embodiment represented in FIG. 11, the aperture
33 is substantially U-shaped, the base of the U being parallel to
the axis passing via the ends 28a and 28b and the ends of the
branches of the U being designed to face the ends 28a and 28b of
the microchannels after the microvalve has been actuated.
[0053] The aperture 33 represented in FIG. 9 passes through the
mini-piston 29 perpendicularly to the plane of the valve card 17.
In the alternative embodiment illustrated in FIG. 12, the aperture
33 is a blind, not a pass-through, aperture.
[0054] In another alternative embodiment represented in FIG. 13,
the movement of the mini-piston 29 is not linear, as in the
previously described embodiments, but rotary. The shape and
disposition of the aperture 33, arranged at a first end of the
mini-piston, are adapted accordingly. In FIG. 13, the mini-piston
is joined to the periphery of the recess 30 by a transverse joining
bar 36 integral to the central part of the mini-piston. The
mini-piston is movable in rotation around a center of rotation
situated at the intersection of the mini-piston and the joining bar
36. The pyrotechnic charge 20 is then arranged in such a way that
the gas release exerts a pressure (arrow 32) on a second end of the
mini-piston causing deformation of the joining bar 36 and rotation
of the mini-piston. The second end of the mini-piston is situated
at a calibrated distance from the opposite wall of the recess 30,
thus bounding a passage 40 serving the same purpose as the vent 34
in the microvalve according to FIG. 10.
[0055] A third embodiment of a microvalve according to the
invention is illustrated in FIGS. 14 and 15. As in the second
embodiment (FIGS. 9 to 12), the mini-piston 29 comprises at its
free end a mobile part 29a wherein the aperture 33 is formed and
which moves in a direction parallel to the plane of the card 17.
The mini-piston comprises in addition a deformable part 29b
integral to the mobile part 29a. Deformation of the deformable part
takes place perpendicularly to the plane of the card 17 in a zone
situated facing the pyrotechnic charge 20. To enable this
deformation, the card 15 containing the microchannels 16 comprises
a cavity 37 situated facing the pyrotechnic charge 20 the location
whereof is represented in a broken line in FIG. 15. Firing of the
pyrotechnic charge causes a gas release which exerts a pressure on
the deformable part 29b in a direction perpendicular to the plane
of the card 17. This deformation of the deformable part of the
mini-piston causes the mobile part 29a to withdraw into the recess
30. The mobile part therefore moves to the right in FIG. 15, thus
bringing the aperture 33 to face the ends 28a and 28b of the
microchannels between which communication is to be established. The
location of the aperture 33 in the mobile part 29a of the
mini-piston is adapted accordingly.
[0056] The microvalves illustrated in FIGS. 9 to 15 are normally
closed microvalves that open when firing of the associated
pyrotechnic charge 20 takes place. To achieve a normally open
microvalve that closes when firing of the associated pyrotechnic
charge 20 takes place, the relative position of the aperture 33 and
of the locations corresponding to the ends 28a and 28b merely have
to be modified so that the aperture 33 establishes communication
between the ends 28a and 28b before the microvalve is actuated.
[0057] Whereas the first embodiment (FIGS. 5, 7 and 8), to
constitute the valve card, requires manufacture of fairly complex
three-dimensional parts with transverse orifices and engagement by
force which may be delicate to implement with a good manufacturing
efficiency, the second and third embodiments (FIGS. 9 to 15) enable
planar techniques only to be used resulting in simpler and
consequently less expensive manufacturing. The invention presents
the advantage of keeping the microvalve in the open or closed
position after actuation without it being necessary to sustain the
actuating force, i.e. the pressure given off by the pyrotechnic
charge.
* * * * *