US20100166585A1

US20100166585A1 - Microdosing Device for Dosing of Smallest Quantities of a Medium

Info

Publication number: US20100166585A1
Application number: US12/600,959
Authority: US
Inventors: Ralf Reichenbach
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2007-09-25
Filing date: 2008-07-25
Publication date: 2010-07-01
Also published as: DE102007045637A1; WO2009040165A1; EP2203645A1

Abstract

A microdosing device for dosing smallest quantities of a medium, having an inlet device, an outlet device, a pump device and a media duct that leads from the inlet device to the outlet device, the inlet device having an inlet opening and an inlet valve having an inlet valve piston, and the outlet device having an outlet opening and an outlet valve having an outlet valve piston, and the pump device having a pump piston. The inlet valve piston, the outlet valve piston and the pump piston are situated on a common diaphragm layer. The microdosing device has the advantage that it is able to be produced in a simple and cost-effective manner.

Description

FIELD OF THE INVENTION

The present invention relates to a microdosing device for the dosing of smallest quantities of a medium, having an inlet device, an outlet device and a pump device, the inlet device having an inlet opening and an inlet valve having an inlet valve piston, and the outlet device having an outlet opening and an outlet valve having an outlet valve piston, and the pump device having a pump piston.

BACKGROUND INFORMATION

Microdosing devices are important in various fields of application, such as in medicinal technology, and are used, for instance, for continually dispensing insulin to a diabetes patient. In this context, smallest quantities of a medium have to be dispensed in an accurately dosed manner.
Various implementations of microdosing devices are known from the related art. Most of these microdosing devices use silicon bulk micromechanics for patterning silicon wafers or glass wafers which are subsequently joined on top of each other by bonding.
A microdosing device is discussed in German patent document DE 197 37 173 A1, which has a microdiaphragm pump and a free jet dosing device connected to it. The microdiaphragm pump and the free jet dosing device are developed in one common component, in this particular construction, these components being built up from a plurality of semiconductor layers. The microdiaphragm pump has a pump diaphragm as the actual active pumping device, which is able to be deflected perpendicular to its plane of extension by using an actuator. In this way, by a separately developed inlet valve, medium may be sucked in from a reservoir and then passed on via an also separately developed outlet valve to the free jet dosing device.
These constructions as well as others known from the related art are consequently very costly, for they frequently have a large number of layers, so that their production is complicated and costly. Furthermore, it is difficult to ensure the tightness of such microdosing devices, both on the inlet and the outlet side.

SUMMARY OF THE INVENTION

By contrast, the microdosing device according to the present invention has the advantage that it is able to be manufactured simply and cost-effectively.
This is achieved, according the exemplary embodiments and/or exemplary methods of the present invention, by a microdosing device for dosing the smallest quantities of a medium, having an inlet device, an outlet device, a pump device and a media duct leading from the inlet device to the outlet device, the inlet device having an inlet opening and an inlet valve having an inlet valve piston, and the outlet device having an outlet opening and an outlet valve having an outlet valve piston, and the pump device having a pump piston, wherein the inlet valve piston, the outlet valve piston and the pump piston are provided on a common diaphragm layer.
That being the case, according to the exemplary embodiments and/or exemplary methods of the present invention only one single diaphragm layer is required, which acts as a diaphragm for both the inlet valve and the outlet valve and also for the pump device. Since only one diaphragm layer is required, the production of the microdosing device is made considerably easier, and a compact design of the overall unit is achievable.
In the use foreseen, according to the exemplary embodiments and/or exemplary methods of the present invention, of a common diaphragm layer for the inlet valve, the outlet valve and the pump device, it may be provided that the inlet valve piston, the outlet valve piston and the pump piston are each positioned in different areas of the diaphragm layer.
This diaphragm layer and the devices situated on it represents the part of the microdosing device that is the most stressed. This part may be produced from a composite of a substrate having a sacrificial layer and a functional layer, using classical micromechanics. This composite may have an SOI wafer, a silicon substrate having an SiO₂sacrificial layer and an epitaxially grown polycrystalline (epipoly-) Si functional layer, or a silicon substrate having an SiGe sacrificial layer and an epipoly-Si functional layer.
One refinement of the exemplary embodiments and/or exemplary methods of the present invention is that, above the diaphragm layer, an upper cover layer and/or below the diaphragm layer a lower cover layer are provided, the upper cover layer and the lower cover layer may be made of a polymer substrate. In this way, the most greatly stressed part of the microdosing device according to the present invention, namely the diaphragm, along with its devices, is implemented using a mechanically high-grade material, while the upper cover layer, which may have the inlet opening and the outlet opening, and the lower cover layer, which, together with the diaphragm, may form the media duct through which the medium is able to be conveyed from the inlet device to the outlet device, is produced from materials that are able to be produced substantially more favorably. Alternatively, patterned glass, pyrex, quartz or silicon wafers are a possibility for the upper cover layer and the lower cover layer. The joining of the individual layers may take place by adhesion or, if necessary, by suitable wafer bonding processes.
It was stated above that the inlet opening and the outlet opening may be provided on the upper cover layer. In a corresponding design it may also be provided that the inlet valve piston as well as the outlet valve piston be situated between the upper cover layer and the diaphragm layer, so that the inlet opening and the outlet opening are able to be sealed, using a movement of the diaphragm layer. In order to move the diaphragm layer appropriately, a pump actuator assigned to the pump device may be provided, for example, which acts upon the pump piston using it, which makes possible a movement of the diaphragm in the vicinity of the pump device, perpendicular to its plane of extension, upwards or downwards. This is connected with a pump action, based on which medium is able to be sucked in through the inlet valve or expelled through the outlet valve, as will be described in detail below.
It was also stated above that, according to one refinement of the exemplary embodiments and/or exemplary methods of the present invention, a media duct is provided between the diaphragm layer and the lower cover layer, through which the medium is able to be conveyed from the inlet device to the outlet device. In such a design it also may be provided that the diaphragm layer, in the vicinity of the inlet valve and in the vicinity of the outlet valve have, in each case, a feed-through opening for the medium to pass through from the area between the upper cover layer and the diaphragm layer into the media duct. This makes possible a manner of functioning of the microdosing device in which, because of an appropriate movement of the pump piston of the pump device, the diaphragm layer is lifted up or pressed down in the vicinity of the pump device, which corresponds to an increase or decrease in the volume of the media duct, whereby, in response to an appropriately opened inlet valve or outlet valve, medium is sucked in via the inlet device, passes through the corresponding feed-through opening into the media duct and passes out of the media duct, in response to an expelling process, through the feed-through opening in the vicinity of the outlet device, so that it is able to be expelled from the microdosing device in response to an appropriately opened outlet valve via the outlet opening.
The microdosing device may basically be designed as a common unit together with all its previously mentioned devices. According to one refinement of the exemplary embodiments and/or exemplary methods of the present invention, it is provided, however, that the inlet valve piston, the outlet valve piston and the pump piston are provided to be on the same diaphragm layer, together with the upper cover layer as a removable unit in a housing which, on its part, provides the lower cover layer. In other words, this enables one to provide the combination unit of the inlet valve piston, the outlet valve piston, the pump piston and the common diaphragm layer as a one-way device which is situated in a housing, that is able to be used in multiple ways, which closes off the one-way unit downwards, using the lower cover layer, so as to form the media duct. This housing may be produced in different ways. According to one refinement of the exemplary embodiments and/or exemplary methods of the present invention, it is provided, however, that it be produced using a cost-effective injection molding process.
Refinements of this housing further involve the housing having a media reservoir that may be removable. In this way, a modular system is implemented in which always only those components have to be replaced or renewed which are exhausted or used up. According to one refinement of the exemplary embodiments and/or exemplary methods of the present invention, it is additionally provided that the housing make available the pump actuator required for the pump device. Furthermore, according to a refinement of the exemplary embodiments and/or exemplary methods of the present invention, the housing is provided with what may be a removable energy supply, such as a battery.
It quite particularly may be the case that the media reservoir and the pump unit are developed as a removable overall unit, that is exchanged as soon as the medium in the reservoir is used up or has drained/deteriorated. Thus, a throw-away unit packaged in a sterile manner may be provided, which is stored in a refrigerator, for example, using which the following changes may be carried out: open housing, remove old unit, sterilize and unpack and insert new unit.
Furthermore, it may be that the housing have an electronic circuit having a programmable interface for programming at least one presetting of the microdosing device. In this way one is able to set individually, for each application, the quantities of the medium that are to be dosed and administered, and at what time. Finally, according to one refinement of the exemplary embodiments and/or exemplary methods of the present invention it is also provided that the housing have a sensor connection for connecting to a sensor according to whose measured value the dosing of the medium is controlled. This sensor connection may be designed to be cable-bound, but also to be wireless.
In order to suck in the medium from a media reservoir, the procedure is generally that an underpressure is generated in the media duct using the pump device, which is effected by increasing the volume of the media duct by moving upwards the pump piston together with the diaphragm layer situated in the vicinity of the pump device. In order to achieve a clear separation of the inlet process from the outlet process, which is important for an exact dosing of the medium, it is provided, according to one refinement of the exemplary embodiments and/or exemplary methods of the present invention, that the outlet valve is self-locking in the media duct, in response to an underpressure. In addition, according to one refinement of the exemplary embodiments and/or exemplary methods of the present invention, it may be provided that the inlet valve is self-locking in response to an overpressure in the media duct. In such a design of the inlet valve and the outlet valve, the advantage comes about that neither the inlet valve nor the outlet valve has to be actively opened or closed, for instance, by an actuator, since the outlet valve is automatically closed during the aspiration process that is connected with an underpressure in the media duct, and the inlet valve is also automatically closed in response to an overpressure that prevails during an expulsion process.
When it was stated before that an underpressure or an overpressure prevails in the media duct, this takes into account the pressure difference compared to the region on the other sides of the inlet valve or the outlet valve, that is, for example, in the media reservoir or in the expulsion area of the microdosing device.
The microdosing device described above is used in medicinal technology, for instance in insulin administration that was mentioned, and also in the continuous local administration of analgesics. Additional fields of application occur in automation technology as pilot control valves or activating valves for larger valves. We might also mention application possibilities in the field of bio/life science, particularly in microanalysis systems.
Exemplary embodiments of the present invention are described in detail below, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a schematic cross sectional representation using the three essential functional blocks of a microdosing device, according to one exemplary embodiment of the present invention.

FIG. 2 a schematic cross sectional representation of the microdosing device according to the exemplary embodiment of the present invention, during the aspiration process.

FIG. 3 a schematic cross sectional representation of the microdosing device, according to the exemplary embodiment of the present invention, during the expulsion process.

FIG. 4 a schematic representation of the microdosing device according to the exemplary embodiment of the present invention, as a combination of a one-way part in a multi-way housing in a closed state.

FIG. 5 a schematic representation of the microdosing device according to the exemplary embodiment of the present invention, as a combination of a one-way part in a multi-way housing in the opened state.

DETAILED DESCRIPTION

One may see in each of FIGS. 1 to 3 a schematic cross sectional representation of a microdosing device according to an exemplary embodiment of the present invention. This microdosing device is used for dosing smallest quantities of a medium, and it has an inlet device 1, an outlet device 2 and a pump device 3, which, for reasons of clarity, is shown in FIG. 1 as three functional blocks separated from one another. In actual fact, these three components of the microdosing device, according to the exemplary embodiment of the present invention, are produced directly as a coherent system on a common substrate, as will be explained below.
Inlet device 1 has an inlet opening 4 and an inlet valve 5 that has an inlet valve piston 6. In an analogous manner, outlet device 2 has an outlet opening 7, an outlet valve 8 and an outlet valve piston 9. Between inlet device 1 and outlet device 2 pump device 3 is provided, which has a pump piston 10, to which is assigned a pump actuator 11. A piezo stack is provided as pump actuator 11, according to the presently described exemplary embodiment of the present invention. However, other principles are usable for pump actuator 11, such as magnetic or hydrodynamic ones. By the way, a bending piezoelectric may also be used. Provided the achievable forces and excursions are sufficient, a piezoelectric thin layer may also be provided for actuating pump piston 10.
Inlet valve piston 6, outlet valve piston 9 and pump piston 10 are provided on a common diaphragm layer 12, which is developed as an epipoly-Si functional layer. Above this diaphragm layer 12, an upper cover layer 13 is developed, and below diaphragm layer 12, a lower cover layer 14 is developed. According to the presently described exemplary embodiment of the present invention, upper cover layer 13 and lower cover layer 14 are both produced from a polymer substrate. Upper cover layer 13 has the inlet opening 4 as well as outlet opening 7, while using lower cover layer 14, a media duct 15 becomes defined between diaphragm layer 12 and lower cover layer 14. The medium, that is to be dosed from inlet device 1 to outlet device 2, is able to be conveyed all the way through this media duct 15. For this, diaphragm layer 12 has a feed-through opening 16 in the vicinity of inlet device 1, and a feed-through opening 17 in the vicinity of outlet device 2. In outlet valve piston 9 provided above feed-through opening 17 in the vicinity of outlet device 2, a feed-through opening 31 is also provided.
Supplying the medium takes place via a supply line 18, which leads to inlet opening 4 of inlet device 1. Subsequently to outlet opening 7 in outlet device 2, a discharge line 19 is provided for conveying onwards the expelled medium. In the final analysis, this enables the following operation of the microdosing device according to the exemplary embodiment:
As may be seen in FIG. 2, because of an upwards movement of pump actuator 11, pump piston 10, together with the area of diaphragm layer 12 assigned to it moves upwards, so that the volume of media duct 15 increases. This reduces the pressure in media duct 15: Compared to the pressure in supply line 18, an underpressure is created. Inlet valve 5 therefore opens, in that inlet valve piston 6 is moved downwards, so that medium from supply line 18, as shown by an arrow in FIG. 2, is able to flow into the media duct, via feed-through openings 16 and the annular gap that is opening in diaphragm layer 12. Based on the underpressure generated in media duct 15 during the aspiration process, outlet valve 8 blocks: In the vicinity of outlet device 2, diaphragm layer 12 is pressed against outlet valve seat 30 that is provided on lower cover layer 14, so that no medium is able to escape from media duct 15.
For the initiation of the expulsion process that may be seen in FIG. 3, after media duct 15 is filled with medium, pump actuator 11 is moved downwards, so that pump piston 10 presses diaphragm layer 12 downwards in the vicinity of pump device 3, onto the upper side of lower cover layer 14. Because of the overpressure generated in this context in media duct 15, inlet valve 5 blocks automatically and outlet valve 8 is opened, so that the medium is expelled into discharge line 19, through feed-through opening 17 that is provided in diaphragm layer 12 in the vicinity of outlet device 2, and subsequently through outlet opening 7 above outlet valve 8.
According to the presently described exemplary embodiment of the present invention, it is now also provided that upper cover layer 13, together with inlet valve piston 6 and pump piston 10 are provided on common diaphragm layer 12, as a removable unit 20, in an external housing 21. This may be seen in FIGS. 4 and 5. Housing 21 swivels open in this context, so that abovementioned removable unit 20 is able to be set onto lower part 22 of the housing, which, on its part, thus forms lower cover layer 14 of the microdosing device. Removable unit 20 may thus be provided as a one-way part which, after being used, is removed from housing 21, that is usable in multiple ways, and exchanged for a new one. The sealing of upper part 23 of housing 21 from removable unit 20 is performed using O-ring seals 32. To open housing 21, upper part 23 and lower part 22 are fastened to each other in a swivelable manner, for instance, by using a film hinge 35. In the closed state, upper part 23 and lower part 22 are fastened to each other at their respective end facing away from the film hinge, using latching mechanisms 33, 34.
According to the presently described first exemplary embodiment of the present invention, upper part 23 of housing 21 has a media reservoir 24 which is connected to the inlet device, so that medium may be conveyed to inlet device 1 from media reservoir 24. If the medium provided in media reservoir 24 is used up, media reservoir 24 may be removed and exchanged for a new one.
In upper part 23 of housing 21 there is also provided a removable energy supply 25, in the form of a battery. The electric energy thus made available is required, for instance, for pump actuator 11, which is also provided in upper part 23 of housing 21, and, as described before, acts upon pump piston 11 of pump device 3. In addition, in upper part 23 of housing 21, an electronic circuit 26 is provided, having a programmable interface for programming at least one presetting of the microdosing device, namely, in the form of a microprocessor.
Ultimately, this provides a microdosing device having the following advantages:
Costly silicon is used only for the mechanically most important layers. This also limits the costly processing of the silicon: Only three micromechanical processing steps are due, namely, two of trenching and one of etching a sacrificial layer.
Because of the cost-reducing use of favorable, and simple to process polysubstrates, namely, in particular, for upper cover layer 13 and lower cover layer 14, the entire device becomes very inexpensive, and thus very competitive.
The size of the patternings, in conjunction with planar technology, also brings along with it the possibility of using thick layer technology, namely, for applying, for instance, special anti-adhesive layers and sealing layers using screen printing to the pump and the valve seat fields.

Claims

1-10. (canceled)

11. A microdosing device for dosing smallest quantities of a medium, comprising:

an inlet device having an inlet opening, and having an inlet valve having an inlet valve piston;

an outlet device having an outlet opening, and having an outlet valve having an outlet valve piston;

a pump device having a pump piston; and

a media duct that leads from the inlet device to the outlet device;

wherein the inlet valve piston, the outlet valve piston and the pump piston are on a common diaphragm layer.

12. The microdosing device of claim 11, wherein the diaphragm layer is a silicon functional layer.

13. The microdosing device of claim 11, wherein at least one of (i) an upper cover layer is provided above the diaphragm layer, and (ii) a lower cover layer is provided below the diaphragm layer.

14. The microdosing device of claim 13, wherein the media duct is between the lower cover layer and the diaphragm layer.

15. The microdosing device of claim 13, wherein the inlet opening and the outlet opening are in the upper cover layer, and the inlet valve piston and the outlet valve piston are between the upper cover layer and the diaphragm layer, so that the inlet opening and the outlet opening are sealable using a movement of the diaphragm layer.

16. The microdosing device of claim 13, wherein the diaphragm layer has respectively at least one feed-through opening in a vicinity of the inlet valve and in a vicinity of the outlet valve, for the medium to pass through from a region between the upper cover layer and the diaphragm layer into the media duct.

17. The microdosing device of claim 13, wherein the inlet valve piston, the outlet valve piston and the pump piston on the common diaphragm layer, together with the upper cover layer, are a removable unit in a housing, which provides the lower cover layer.

18. The microdosing device of claim 17, wherein the housing has at least one of a removable media reservoir, a pump actuator, and a removable energy supply and at least one of an electronic circuit having a programmable interface for programming at least one presetting, a sensor connection for connecting to a sensor, according to whose measured value the dosing is controllable.

19. The microdosing device of claim 18, wherein the media reservoir and the pump unit are a removable overall unit.

20. The microdosing device of claim 11, wherein at least one of the inlet valve and the outlet valve each have a sealing layer to improve the sealing.

21. The microdosing device of claim 11, wherein at least one of (i) an upper cover layer is provided above the diaphragm layer, and (ii) a lower cover layer is provided below the diaphragm layer, and wherein the upper cover layer and the lower cover layer are produced from a polymer substrate.

22. The microdosing device of claim 13, wherein the inlet valve piston, the outlet valve piston and the pump piston on the common diaphragm layer, together with the upper cover layer, are a removable unit in a housing, produced using an injection molding process, which provides the lower cover layer.

23. The microdosing device of claim 11, wherein at least one of the inlet valve and the outlet valve each have a sealing layer to improve the sealing, the sealing layer having a soft and flexible material, which is a parylene or a silicone.