EP0951617B1 - Micropump with a built-in intermediate part - Google Patents

Description

The invention relates to a micropump and its manufacturing process, this micropump comprising at least one base plate, at least one upper plate and an intermediate plate interposed between the two other plates and made of a machinable material so as to define a pumping, at least one fluid inlet control member for connecting the pumping chamber with at least one inlet of the micropump, and at least one fluid outlet control member for connecting the pumping chamber with at least one an outlet from the micropump, the pumping chamber comprising a movable wall machined in the intermediate plate, said movable wall being able to move in two opposite directions during the suction or expulsion of said fluid in the pumping chamber, the upper plate being provided with at least one orifice connecting a cavity with at least part of the movable wall, actuation means fixed on the free face of the upper plate being provided to move said movable wall in order to cause a periodic variation in the volume of the pumping chamber, said actuating means comprising an actuating plate made of a material which can be machined so as to define a moving area.

In certain micropumps of the prior art which are called "PIN-TYPE", one of the elements of the actuation means is constituted by an intermediate part which is intended to bring the piezoelectric device into contact with the movable wall of the chamber pumping. The fabrication by micro-machining of this intermediate part and its mounting in the micropump device require great precision in order to obtain a micropump operating in a safe and regular manner.

Such a micropump is described, for example, in international application WO 9518307 from the company WESTONBRIDGE. FIG. 1 represents one of the embodiments of the micropump described in the aforementioned document. This micropump comprises a base plate 82, an intermediate plate 86, an upper plate 88, actuating elements 87 intended to cooperate with the piezoelectric device 80 and an intermediate piece 84 in the form of a pushpin connected by its flat head to the elements d actuation 87.

It is understood that the use of such an intermediate part 84, necessary for the proper functioning of the micropump, causes significant complications during the manufacture of this micropump.

The objective of the present invention is to provide a micropump having an intermediate part whose manufacture is simplified while making it possible to obtain a micropump operating in a reliable and constant manner.

According to the invention, this object is achieved thanks to the fact that said actuating plate is made of a material which can be machined so as to define said cavity, an intermediate piece machined in the upper plate being fixed on the actuating plate of so as to establish contact with the movable wall.

It is understood that the manufacture of the intermediate piece from the upper plate avoids manufacturing the intermediate piece independently of all the other elements of the micropump so that this intermediate piece integrates perfectly into the micropump as will be explained later .

The invention will be better understood and secondary characteristics and their advantages will become apparent during the description of two embodiments given below by way of example.

• la figure 1, précédemment décrite, représente la coupe d'une micropompe de l'art antérieur ;
• la figure 2 représente schématiquement et partiellement, en coupe, un premier mode de réalisation de la micropompe selon l'invention ;
• la figure 3 est une figure analogue à la figure 2 représentant un deuxième mode de réalisation de la micropompe selon l'invention ;
• les figures 4A à 4D représentent certaines étapes de fabrication d'une micropompe selon un procédé de fabrication préférentiel ; et
• les figures 5A à 5F représentent les différentes étapes du procédé de fabrication d'une micropompe selon l'invention.

Reference will be made to the accompanying drawings, in which:

• Figure 1, previously described, shows the section of a micropump of the prior art;
• Figure 2 shows schematically and partially, in section, a first embodiment of the micropump according to the invention;
• Figure 3 is a figure similar to Figure 2 showing a second embodiment of the micropump according to the invention;
• FIGS. 4A to 4D represent certain stages in the manufacture of a micropump according to a preferred manufacturing process; and
• FIGS. 5A to 5F represent the different stages of the process for manufacturing a micropump according to the invention.

The partial and schematic sections of the two preferred embodiments of a micropump illustrated in FIGS. 1 and 2 represent only the central part of a micropump as it is delimited by the zone A of FIG. 1.

Referring to FIG. 2, the central part of this micropump comprises a base plate 1 and an upper plate 2 which are preferably made of glass such as Pyrex. Between these two plates 1 and 2 is interposed the intermediate plate 3 which delimits, with the base plate 1, the pumping chamber 4. The central part of the intermediate plate 3 constitutes a movable wall 5 intended to allow the variation of the volume of the pumping chamber 4 under the action of a piezoelectric device 6 surmounting the micropump.

An actuating plate 7 is inserted and fixed between the piezoelectric device 6 and the upper plate 2 by creating a cavity 8 between the actuating plate 7 and the upper plate 2.

A free face 9 of the upper plate 2 is preferably fixed, by anodic welding to a portion of the actuating plate 7, on either side of the cavity 8. On the side opposite to the cavity 8, the face free 10 of the actuating plate 7 is connected to the piezoelectric device, in the extension of the central part of the cavity 8. Between the piezoelectric device 6 and the central part of the cavity 8, the central part of the actuating plate 7 constitutes a mobile zone 11.

The cavity 8 is extended at the level of the upper plate 2 by a connection orifice 12 of annular shape surrounding an intermediate part 13 produced from the same original part as the upper plate 2.

The cavity 8 also has an annular shape and surrounds a portion of the mobile area 11 fixed to the intermediate piece 13. At the periphery of the connection orifice 12, the upper plate 2 is in simple contact, without fixing, with the wall mobile 5 (zone 16 forming a stopper) so as to block any movement of the mobile wall 5 beyond this contact zone. This fixing is preferably avoided by virtue of an insulating layer covering the zone 16 forming a stopper of the upper plate 2, this layer being for example made of silicon oxide.

There is also a annular intermediate cavity 14 between the upper plate 2 and the intermediate plate 3, this intermediate cavity resulting from the withdrawal of material from the intermediate plate 3, being in the extension of a portion of the cavity 8, of the 'other side of the upper plate 2, and placed outside with respect to the connection orifice 12.

In the same way as the zone 16 forming a stopper limits the upward movement of the movable wall 5, stops 17, fixed on the face of the movable wall 5 located opposite the pumping chamber 4, limit the downward movement of the movable wall 5.

It should be noted that the upper plate 2 and the intermediate plate 3 are fixed, preferably by anodic welding, to one another in the contact zones located outside with respect to the intermediate cavity 14. The plates intermediaries 3 and actuation 7 are preferably made of a semiconductor such as silicon.

Preferably, the actuation means, consisting in particular of the piezoelectric device 6, the intermediate piece 13 and the movable wall 5 are centered around the same axis.

Because the intermediate part 13 and the upper plate 2 come from the same initial plate, it is understood that the manufacture of the micropump device is considerably simplified, that the problems of tolerance and compatibility between the various constituent elements of this micropump are strongly minimized or even eliminated. In fact, the thickness of the intermediate piece 13 being necessarily identical to the thickness of the upper plate 2, during assembly, the adjustment between the pieces of the micropump device is then possible with a high degree of precision.

The first preferred embodiment illustrated in FIG. 2 provides that the intermediate plate 3 and the actuation plate 7 delimit a sealed space, composed of the cavity 8, the connection orifice 12 and the intermediate cavity 14, a partial vacuum that can be set up within this sealed space.

The sealing of the aforementioned space is made possible by the very high precision adjustment between the parts making up the micropump (mobile zone 11 of the actuating plate 7, upper plate 2, intermediate part 13, and mobile wall 5) . The strict identity between the thickness of the intermediate piece 13 and the upper plate 2 is a very important characteristic for obtaining a good fit between the pieces, which allows the aforementioned space to be sealed.

According to an advantageous characteristic, the presence of a partial vacuum in the sealed space 8, 12, 14 makes it possible to pull the movable wall 5 of the pumping chamber 4 in the direction of the upper plate 2.

If a partial vacuum is established in the sealed space 8, 12, 14, it is preferable not to fix the intermediate piece 13 to the movable wall 5 so as not to create residual stresses at this fixing.

According to a second preferred embodiment shown in FIG. 3, the sealed space 8, 12, 14 cannot be placed under partial vacuum, but a conduit 15 connects this sealed space outside the micropump. Preferably, this conduit 15 is produced in the upper part of the actuating plate 7 and communicates with the cavity 8 by connecting the latter with the outside of the part of the micropump shown in FIG. 3 so that the 'space defined above has a pressure equal to that of the outer space into which the conduit 15 opens, this pressure may be atmospheric pressure.

In the case where a duct 15 is provided connecting the sealed space 8, 12, 14 with the exterior of the pump, if it is desired to pull the movable wall 5 in the direction of the piezoelectric device 6, it is necessary to fix the intermediate piece 13 to the movable wall 5, this fixing can be achieved by anodic welding.

Three preferred methods of manufacturing a micropump according to the invention as described above will now be presented.

Whatever the manufacturing process among the three that will be presented, we must first provide an actuating plate 7, an upper plate 2, an actuating device and a set intermediate plate 3 - basic plate 1 in which the intermediate plate 3 is fixed to the base plate 1, a pumping chamber 4 being formed between these two plates, for example by prior machining of the intermediate plate 3.

• a) usinage de la plaquette d'actionnement 7 de façon à créer la cavité 8,
• b) fixation de la plaquette d'actionnement 7 à la plaquette supérieure 2,
• c) usinage de la plaquette supérieure 2 de façon à créer l'orifice de liaison 12 et la pièce intermédiaire 13,
• d) fixation de l'ensemble plaquette supérieure 2 - plaquette d'actionnement 7 à l'ensemble plaquette intermédiaire 3 - plaquette de base 1, et
• e) fixation d'un dispositif d'actionnement, tel que piézoélectrique 6, à la plaquette d'actionnement 7.

According to a first method of manufacturing a micropump according to the invention, the following steps are carried out:

• a) machining the actuating plate 7 so as to create the cavity 8,
• b) fixing of the actuation plate 7 to the upper plate 2,
• c) machining of the upper plate 2 so as to create the connection orifice 12 and the intermediate part 13,
• d) fixing of the upper plate assembly 2 - actuation plate 7 to the intermediate plate assembly 3 - base plate 1, and
• e) fixing of an actuating device, such as piezoelectric 6, to the actuating plate 7.

A favorable solution as long as the manufacturing technique provides, in the case of the first manufacturing process, that the machining of the connection orifice 12 is obtained by electroerosive machining process or EDM (Etectro Discharge Machining) , by ultrasonic or UD (Ultrasonic Drilling) machining process or by chemical attack on the glass.

According to a second method of manufacturing a micropump, it is possible, by machining the connection orifice 12 and the intermediate piece 13 in two stages, to obtain better precision on the ribs of the various elements of the micropump. so that it presents a more reliable operation.

• a) usinage de la plaquette d'actionnement 7 de façon à créer la cavité 8,
• b) usinage de la plaquette supérieure 2 de façon à créer partiellement l'orifice de liaison 12 et la pièce intermédiaire 13,
• c) fixation de la plaquette d'actionnement 7 à la plaquette supérieure 2,
• d) usinage de la plaquette supérieure 2 de façon à achever la création de l'orifice de liaison 12 et la pièce intermédiaire 13,
• e) fixation de l'ensemble plaquette supérieure 2 - plaquette d'actionnement 7 à l'ensemble plaquette intermédiaire 3 - plaquette de base 1, et
• f) fixation d'un dispositif d'actionnement, tel que piézoélectrique 6, à la plaquette d'actionnement 7.

According to this second manufacturing process, the following steps are carried out:

• a) machining the actuating plate 7 so as to create the cavity 8,
• b) machining of the upper plate 2 so as to partially create the connection orifice 12 and the intermediate part 13,
• c) fixing of the actuation plate 7 to the upper plate 2,
• d) machining of the upper plate 2 so as to complete the creation of the connection orifice 12 and the intermediate piece 13,
• e) fixing of the upper plate assembly 2 - actuation plate 7 to the intermediate plate assembly 3 - base plate 1, and
• f) fixing of an actuating device, such as piezoelectric 6, to the actuating plate 7.

It is advantageously possible here that the partial machining of the upper plate 2 is carried out by an electro-erosive machining process (EDM) or by an ultrasonic machining process (UD).

It is also possible that the completion of the creation of the connection orifice 12 and of the intermediate piece 13 is practiced by chemical attack on the upper plate 2.

On the other hand, as illustrated in FIGS. 4A to 4D, in the context of the second method of manufacturing the micropump, it is possible to deposit one or more metallic layers on one face of the upper plate 2 before starting the creation of the connecting orifice 12 and the intermediate part 13 (step b) by machining this face. In fact, the metal layer or layers can be located on one or the other of the two faces of the upper plate 2: on the face undergoing the partial creation of the orifice 12 and of the part 13 or on the machined face upon completion of the creation of this orifice but in all cases this or these metal layers are on the side opposite to the actuation plate 7.

As illustrated in FIG. 4A, a layer of chromium 2a, followed by a layer of copper 2b, is deposited on the upper plate 2. Then (FIG. 4B), the upper plate 2 is machined so as to partially create the connection orifice 12 of the intermediate part 13, this partial machining not relating to the entire thickness of the upper plate 2. As can be seen in FIG. 4C which corresponds to step c) of the second manufacturing process, the actuating plate 7, already machined and having the cavity 8, is fixed to the upper plate 2, for example by anodic welding on the side opposite to that carrying the metal layers. FIG. 4D illustrates step d) of the second manufacturing process and shows that an additional machining of the upper plate 2 makes it possible to complete the creation of the annular connection orifice 12 surrounding the intermediate piece 13 so that the connection orifice 12 communicates with the cavity 8 and that the intermediate piece 13 is integral with the actuation plate 7 at the level of the central zone of the mobile zone 11.

A third method of manufacturing a micropump making it possible to minimize the thickness tolerances, in particular at the level of the upper plate 2 and of the intermediate piece 13, will now be presented in relation to FIGS. 5A to 5F.

• a) dépôt d'une couche de maintien 18 sur une face de la plaquette supérieure 2 (figure 5B),
• b) usinage de la plaquette supérieure 2 sur la face opposée à la face en contact avec la couche de maintien 18 de façon à créer l'orifice de liaison 12 et la pièce intermédiaire 13, la couche de maintien 18 pouvant être également usinée (figure 5C), mais que partiellement,
• c) fixation de la plaquette d'actionnement 7 sur la face de la plaquette supérieure 2 qui est opposée à la face en contact avec la couche de maintien 18 (figure 5D),
• d) retrait de la couche de maintien 18 (figure 5E),
• e) fixation de l'ensemble plaquette supérieure 2 - plaquette d'actionnement 7 à l'ensemble plaquette intermédiaire 3 - plaquette de base 1 (figure 5F), et
• f) fixation d'un dispositif d'actionnement, tel que piézoélectrique 6, à la plaquette d'actionnement 7.

According to this third manufacturing process, the following steps are carried out:

• a) depositing a retaining layer 18 on one face of the upper plate 2 (FIG. 5B),
• b) machining of the upper plate 2 on the face opposite to the face in contact with the retaining layer 18 so as to create the connection orifice 12 and the intermediate part 13, the retaining layer 18 which can also be machined (FIG. 5C), but only partially,
• c) fixing of the actuation plate 7 on the face of the upper plate 2 which is opposite to the face in contact with the retaining layer 18 (FIG. 5D),
• d) removal of the retaining layer 18 (FIG. 5E),
• e) fixing of the upper plate assembly 2 - actuation plate 7 to the intermediate plate assembly 3 - base plate 1 (FIG. 5F), and
• f) fixing of an actuating device, such as piezoelectric 6, to the actuating plate 7.

In this third manufacturing method, the retaining layer 18 allows the production, by machining in one step, of the connection orifice 12 and of the intermediate piece 3 while allowing the upper plate 2 and the intermediate piece 13 to remain completely made aligned during the manufacturing process.

Preferably, the retaining layer is a polymer or a metal and the plates constituting the micropump device are fixed together, if necessary, by anodic welding.

The three manufacturing methods which have just been described are suitable for producing the first or the second embodiment of the micropump as shown in FIGS. 2 and 3.

In the case of the first embodiment of micropump shown in FIG. 2, in addition to the process steps mentioned above, preferably but not necessarily, a partial vacuum is established within the sealed space formed by the cavity 8, of the connection orifice 12 and of the intermediate cavity 14.

In the case of the second embodiment shown in FIG. 3, in addition to the process steps mentioned above, a pipe 15 is connected connecting the sealed space formed by the cavity 8, the connection orifice 12 and the intermediate cavity 14 , this space being delimited by the intermediate plate 3 and the actuation plate 7, outside the micropump. Preferably, when fixing the upper plate assembly 2 - actuation plate 7 to the intermediate plate assembly 3 - base plate 1, the intermediate part 13 is fixed to the movable wall 5, for example by welding anodic.

Claims (25)

1. Micropump comprising at least one base plate (1), at least one upper plate (2) and an intermediate plate (3) interposed between the other two plates (1, 2) and made of a material machinable so as to define a pumping chamber (4), at least one fluid inlet control member for connecting the pumping chamber (4) with at least one inlet of the micropump, and at least one fluid outlet control member for connecting the pumping chamber (4) with at least one outlet of the micropump, the pumping chamber comprising a movable wall (5) machined in the intermediate plate (3), said movable wall (5) being adapted to move in two opposite directions during suction or delivery of said fluid in the pumping chamber (4), the upper plate being provided with at least one opening (12) linking a cavity (8) with at least one portion of the movable wall (5), actuation means (6, 7, 13) fixed on the free face (9) of the upper plate (2) being provided to displace said movable wall (5) in order to bring about a periodic variation of the volume of the pumping chamber (4), said actuation means comprising an actuating plate (7) constituted by a material machinable so as to define a movable area (11), characterized by the fact that said actuating plate (7) is constituted by a material machinable so as to define said cavity (8); an intermediate part (13) machined in the upper plate (2) being fixed on the actuating plate (7) so as to establish contact with the movable wall (5).
2. Micropump according to Claim 1, characterized by the fact that the intermediate part (13) is fixed to the mobile wall (5).
3. Micropump according to Claim 1, characterized by the fact that the intermediate plate (3) and the actuating plate (7) define a tight space (8, 12, 14).
4. Micropump according to Claim 3, characterized by the fact that a partial vacuum is established within the tight space (8, 12, 14).
5. Micropump according to Claim 2, characterized by the fact that a conduit (15) links the tight space (8, 12, 14) with the outside of the micropump.
6. Micropump according to any one of the preceding Claims, characterized by the fact that means (16, 17) limit the displacement of the movable wall (5).
7. Micropump according to any one of the preceding Claims, characterized by the fact that the actuation means (6, 7, 13) are composed in particular of a piezoelectric device (6).
8. Micropump according to any one of the preceding Claims, characterized by the fact that the base and upper plates (1, 2) are constituted of glass such as pyrex.
9. Micropump according to any one of the preceding Claims, characterized by the fact that the intermediate and actuating plates (3, 7) are constituted of a metal such as silicon.
10. Micropump according to any one of the preceding Claims, characterized by the fact that the actuation means (6), the intermediate part (13) and the movable wall (5) are centered about the same axis.
11. Process for manufacturing a micropump as described in Claim 1, in which the following steps are carried out:

    a) machining of the actuating plate (7) so as to create the cavity (8),

    b) fastening of the actuating plate (7) to the upper plate (2),

    c) machining of the upper plate (2) so as to create the linking opening (12) and the intermediate part (13),

    d) fastening of the upper plate (2)/actuating plate (7) assembly to the intermediate plate (3)/base plate (1) assembly, and

    e) fastening of an actuation device, such as a piezoelectric one (6), to the actuating plate (7).
12. Process according to Claim 11, characterized by the fact that the machining of the linking opening (12) is obtained by electro-erosive machining or EDM (Electro Discharge Machining) process, by ultrasonic machining or UD (Ultrasonic Drilling) process or by chemical attack of the glass.
13. Process for manufacturing a micropump as described in Claim 1, in which the following steps are carried out:

    a) machining of the actuating plate (7) so as to create the cavity (8),

    b) machining of the upper plate (2) so as to partially create the linking opening (12) and the intermediate part (13),

    c) fastening of the actuating plate (7) to the upper plate (2),

    d) machining of the upper plate (2) so as to terminate creation of the linking opening (12) and the intermediate part (13),

    e) fastening of the upper plate (2)/actuating plate (7) assembly to the intermediate plate (3)/base plate (1) assembly, and

    f) fastening of an actuation device, such as a piezoelectric one (6), to the actuating plate (7).
14. Process according to Claim 13, characterized by the fact that the partial machining of the upper plate (2) is obtained by electro-erosive machining or EDM (Electro Discharge Machining) process, or by ultrasonic machining or UD (Ultrasonic Drilling) process.
15. Process according to Claim 13 or 14, characterized by the fact that the termination of the creation of the linking opening (12) and of the intermediate part (13) is made by chemical attack of the upper plate (2).
16. Process according to Claim 13, characterized by the fact that one or more metal layers (2a, 2b) are deposited on a face of the upper plate (2) before starting the creation of the linking opening (12) and of the intermediate part (13), the metal layer or layers being removed after having created the linking opening (12) and the intermediate part (13).
17. Process according to Claim 16, characterized in that the metal layer or layers are deposited on the face of the upper plate (2) undergoing the partial creation of the linking opening (12) and of the intermediate part (13).
18. Process according to Claim 16, characterized in that the metal layer or layers are deposited on the face of the upper plate (2) machined during termination of the creation of the linking opening (12) and of the intermediate part (13).
19. Process according to any one of Claims 16 to 18, characterized by the fact that a layer of chromium (2a) followed by a layer of copper (2b) are deposited.
20. Process for manufacturing a micropump as described in Claim 1, in which the following steps are carried out:

    a) deposit of a holding layer (18) on a face of the upper plate (2),

    b) machining of the upper plate (2) on the face opposite the face in contact with the holding layer (18) so as to create the linking opening (12) and the intermediate part (13), the holding layer (18) also being able be be machined, but only partially,

    c) fastening of the actuating plate (7) on the face of the upper plate (2) which is opposite the face in contact with the holding layer (18),

    d) removal of the holding layer (18),

    e) fastening of the upper plate (2)/actuating plate (7) assembly to the intermediate plate (3)/base plate (1) assembly,

    f) fastening of an actuation device, such as a piezoelectric one (6), to the actuating plate (7).
21. Process according to Claim 18, characterized by the fact that the holding layer (18) is a polymer or a metal.
22. Process according to any one of Claims 11 to 19, characterized by the fact that the plates are fixed by anodic welding.
23. Process according to any one of Claims 11 to 20, characterized by the fact that, during fastening of the upper plate (2)/actuating plate (7) assembly to the intermediate plate (3)/base plate (1) assembly, the intermediate part (13) is fixed on the movable wall (5).
24. Process according to Claim 21, characterized by the fact that a conduit (15) is machined, linking the tight space (8, 12, 14) defined by the intermediate plate (3) and the actuating plate (7) with the outside of the micropump.
25. Process according to any one of Claims 11 to 22, characterized by the fact that a partial vacuum is established within the tight space (8, 12, 14).