EP2222959A1

EP2222959A1 - Method for supplying a fluid and micropump for said purpose

Info

Publication number: EP2222959A1
Application number: EP08847009A
Authority: EP
Inventors: Frank Bartels; Severin Dahms; Uwe Kampmeyer; Markus Rawert
Original assignee: Bartels Mikrotechnik GmbH
Current assignee: Bartels Mikrotechnik GmbH
Priority date: 2007-11-05
Filing date: 2008-09-25
Publication date: 2010-09-01
Anticipated expiration: 2028-09-25
Also published as: ATE543002T1; WO2009059664A1; EP2222959B1; US20110005606A1

Abstract

A device includes a number of N≧2 pump chambers having N separate chamber volumes, each of which may be altered independently of the other(s). The volume changes of the pump chambers occur periodically with substantially the same frequency (f). The device further includes N actuators for changing the respective chamber volumes and valves for establishing the pumping direction, and finally a common inlet and outlet. The pump chambers of the device are disposed in series one behind the other, and the forms of the periods of volume changes of all pump chambers are substantially identical. Moreover, an ideal phase offset PHI of approximately 180° exists between the volume change of the chamber volumes of two sequential pump chambers.

Description

International Patent Application 4901

Bartels Mikrotechnik GmbH 25.09.2008

Method of conveying a fluid and micropump therefor

The invention relates to the field of pumped delivery, and more particularly to methods of pumping small and minute quantities of fluid, and more particularly to pumps constructed of pumping chambers, diaphragm actuators and valves.

State of the art and disadvantages

Pumps for conveying fluids, ie gases and liquids and mixtures thereof have long been known and available in a wide variety.

Also, the still young discipline of microsystems technology compared to other branches of industry requires corresponding funding. Some of the pumping techniques known from the general state of the art have been transferred to the field of microsystem technology with varying degrees of success in recent years. A frequently underestimated problem here is in the

Provision of a bladder-tolerant device, since, due to the small dimensions of the pumping chambers used in micropumps even the smallest bubbles lead to blockages of the channels and / or pumping chambers.

BESTATIGUNGSKOPIE Gas bubbles can, for example, occur during the first use of the pump, by bubbles already present in the pumping medium, by the formation of gas bubbles from a gas initially dissolved in the liquid, or by a strong negative pressure.

For example, pumps based on silicon are known from the prior art, in which essential parts such as pumping diaphragm and / or valves made of silicon are produced by means of etching techniques. Such a construction can be found, inter alia, in H.T. G. van Lintel, F. CM. Van de Pol, "A Piezoelectric Micropump Based on Micromachining of Silicon," Sensors and Actuators, 15, 1988, pp. 153-167 Such pumps generally are sensitive to gas bubbles in the fluid stream and are therefore often lined with hydrophilic coatings, the high Hydrophilicity of the base material silicon is advantageous, however, the possibilities of avoiding problems caused by gas bubbles entrained in the fluid flow are limited, in particular in the case of single-chamber pumps.

As drive mostly piezoceramic and thermally, electrostatically or electromagnetically acting actuators are used.

Furthermore, peristaltic pumps are described, which have the ability due to their multi-chamber structure to press gas bubbles, which are located in a first chamber, by emptying them in the next chamber, without any risk of retraction of the gas bubble. Such a structure is for example the document WO 95/20105 removable. The juxtaposition of several individual pumps creates a pump cascade. By a phase offset, which is for example in three chambers 120 °, a continuous transport of the fluid is achieved in one direction.

Although such peristaltic pumps on the one hand robust against gas bubbles in the fluid react, they always need at least three chambers, otherwise the phase offset would be 180 °, so that the

Conveying direction would no longer be defined. Furthermore, the drive of the three or more chambers requires a corresponding amount of space and energy for operation.

Object of the invention and solution

The object of the invention is therefore to provide a device and a method for conveying fluids, which is miniaturizable, energy-saving and bubble-tolerant and also allows effective promotion.

Accordingly, an apparatus according to claim 1 and a method according to claim 13 are proposed. Further embodiments are set forth in the dependent claims and the following description and the accompanying drawings. description

The invention particularly relates to an apparatus and a method for the bubble-tolerant and effective delivery of a fluid, which, due to its simple and robust construction, especially for use in the

Microsystem technology, such as in the field of life sciences, medical technology, personal hygiene, cosmetics, etc. Also, the above invention is well suited for use in environmental technology, in toys or other particularly harsh environments.

Accordingly, the invention comprises in particular the following basic components:

- A number of at least two pumping chambers, each having its own chamber volume, and each of which chamber volume is variable independently of all others. In this case, the volume changes of the pumping chambers essentially each run periodically at a substantially identical frequency f;

- N actuators to change the respective

Chamber volumes, where N corresponds to the number of pumping chambers and each actuator can be assigned to a specific pumping chamber;

one or more valves for determining the pumping direction;

a common inlet and a common outlet, each of which is independent of the other and Preferably, it is designed so that it can be designed elastic hoses, or according to alternative embodiments as a screw thread, as a Luer connection, as a bore or as a plug connection;

- And according to a preferred embodiment, a common housing into which the components described can be integrated.

The invention is characterized in particular by the fact that the N pumping chambers are arranged serially one behind the other, and that the forms of the periods of the volume changes of all pumping chambers are substantially identical, and that between the volume change of the chamber volume of two successive pumping chambers an ideal phase offset PHI of approximately 180 ° exists.

Depending on the nature of the actuators, their control takes place, for example, electrically, mechanically, magnetically, and preferably the drive curve of the actuator predetermines the change in volume in the respective pumping chamber. An ideal phase offset is from an actual one

Phase offset PHI * delimit; By this it is meant that in certain circumstances, as will be shown, a deliberate deviation from the ideal value can be sought, but that in the basic configuration from each pumping chamber to the next, a phase shift PHI of 180 ° is to be set. Thus, in the case of four pumping chambers, the first and third would be in phase, and the second and fourth would be just opposite the first and third chambers. According to a preferred embodiment of the device according to the invention, this is characterized in that N = 2, so it consists of just two pumping chambers. This is the smallest of the possible chamber numbers; As experiments have shown, the device is capable, provided it has a structure according to the teaching set forth herein and is used in accordance with the method according to the invention to be described, all the requirements as set forth above

Problem arises, especially the requirement for an excellent bladder tolerance.

To a sufficiently safe, i. in particular also bubble-tolerant and efficient operation, the actual phase offset PHI * should preferably deviate not more than + 7% and more preferably not more than + 3% from the ideal phase offset PHI. Depending on the pumping medium, density, temperature, flow rate and structure of the pumping device, these numbers may vary; In general, a smaller deviation is always preferable. Preferably also the N. and the N + 2. Actuator are each addressed with the same control curve, so that at least all even or all odd pumping chambers work in exactly the same phase.

The device according to the invention is intended for use with fluids. In this case, the fluid may be a liquid, a gas, or a liquid-gas mixture, in which the gas may be dissolved in the liquid and / or in the form of bubbles. Such liquids can for example, be blood or other body fluids in which dissolved gas is present, which shows under certain pressure changes in the form of (mostly undesirable) gas bubbles, which in turn can block the pumping device. By using the device according to the invention, such gas bubbles can no longer lead to a blockage of the pumping device, which is of particular importance in the field of medical technology.

According to a preferred embodiment of the device according to the invention, each pumping chamber preferably comprises at least one own inlet valve and / or at least one outlet valve, and particularly preferably two separate inlet valves and two separate outlet valves. Experiments have shown that in the

Use of double valves a particularly high degree of reliability in the operation of the device can be achieved.

According to a particularly preferred embodiment, the valves are arranged and configured such that the directional changes in the fluid flow caused by them are minimized. This minimizes the energy required to transport the fluid and further reduces the likelihood of gas bubbles settling. The exact configuration of the fluid components depends on the type of actuators used, pumping chamber shapes, etc.; As a rule, however, it can be said that angle changes in the fluid path should not be abrupt and in particular right angles should be avoided. Change from one fluid level to another Sufficiently slow and shallow, meaning that the bore connecting both fluid planes should have a diameter at least as long as their length.

According to a preferred embodiment of the device according to the invention this is characterized in that it comprises the change of the respective chamber volumes Piezomembranaktuatoren. In particular disk or plate-shaped actuators are particularly preferred. However, there are others too

Actuators for changing the respective chamber volumes conceivable, such as mechanical, thermal, magnetic, electrostatic or other, a change in the chamber volume inducing actuators, in particular those are particularly preferred, which have a particularly low energy and space requirements.

According to another preferred embodiment, all components in contact with the fluid are made of polyphenylsulfone (PPSU). This material offers desirable advantages, in particular with regard to the joining and manufacturing methods preferred for joining the invention. Of course, the invention is in no way limited to this material. Thus, for example, it may be necessary to specially coat the fluid-related parts in the medical or environmental field, for example by biocompatible or other, especially inert, materials to adapt the device to the specific requirements. Also other materials, like Silicon, metals or glasses are conceivable, it being necessary to ensure in the case of materials which are less extensible that the actuators can still lead to a change in the chamber volume according to the invention.

According to a further embodiment of the device, all the components to be connected to one another can be connected by means of the "laser transmission welding." This method is particularly suitable for joining plastics and, in addition to short production times, offers the possibility of producing a hermetically sealed connection without adhesives, and of strength Depending on the wavelength of the laser used for welding, care must be taken to connect one absorbing and one transparent component to each other.

According to a further embodiment, the device comprises geometric configurations such that a faulty assembly of the components is largely excluded. This is particularly advantageous if the assembly of the device is done manually, and as a result of possibly similar components of the individual pumping chambers, or due to almost symmetrical configurations of these components there is a risk of confusion. Since the correction of such incorrect assembly costs time and at worst results in defective pumps, such mounting errors are to be avoided in any case. This can according to the invention be done by the fact that certain marks or projections are on the housing, which allow the mounting of other components only in a very specific way, so that incorrect installation is practically impossible, since they attract attention immediately or are possible only with damage of the component. Such mounting aids are therefore preferably made of one or more raised parts and with these corresponding recesses on other components. Particular preference is given to those embodiments which extend in a direction perpendicular to the individual layers or functional planes through the entire housing, so that only a minimal number of such embodiments is necessary.

According to a particularly preferred embodiment, the device is characterized in that the necessary for the production of a single pumping chamber components, in particular the or the valves and the actuator, compared to the components required for the production of another pumping chamber of the same device substantially interchangeable or identical with these is designed or are. In other words, if possible, all actuators, all valves and possibly other components that are repeated in each pumping chamber are in each case configured identically. In this way, on the one hand, the likelihood of confusion during assembly is reduced, on the other hand, the costs are minimized in the production, since a correspondingly larger number of identical components can normally be produced more cost-effectively than several different variants with correspondingly smaller numbers.

According to a most preferred embodiment of the device according to the invention, it comprises the following components, wherein the enumeration order essentially corresponds to the assembly order:

a bottom element with a recess, and an inlet leading into the recess and an outlet leading out of the recess, and also between the inlet and the outlet in the same plane fluid structures for guiding the fluid to be conveyed to the valves and for fluidic Konnektierung both pumping chambers and for connection to the inlet and the outlet;

- A valve film which is inserted into the recess and carries the moving parts of the valves;

an intermediate layer which can be inserted into the recess above the valve film and has openings which form the non-moving parts of the valves;

a protective layer which can be inserted into the recess above the intermediate layer and which forms, with the intermediate layer, two cavities lying in a plane, which serve as pumping chambers;

two actuators with electrodes and electrical connections, wherein each actuator is arranged in each case congruent with the underlying pumping chamber, and wherein by operation of the actuator, the chamber volume of the associated pumping chamber is variable;

a cover element, the outer contours of which substantially correspond to those of the floor element, and which can be placed on the floor element and which, after being connected to the floor element, terminates the recess in such a way that the components located in its interior are protected from external influences.

In this case, the bottom element, the intermediate layer and the cover element can be connected to one another in a fluid-tight manner.

It is clear that this enumeration can be supplemented by further, meaningful or necessary further components for the corresponding application and therefore should not be regarded as conclusive.

According to another embodiment, the device is not constructed as described above as an integrated variant, but by juxtaposing separate individual pumps. It thus consists of a serial arrangement of N separate, each comprising only a single pumping chamber individual pumps, which are designed to be connected to each other by means of fluidic lines. Such lines are preferably made of a material as unyielding material to avoid the loss of energy by (unwanted) widening of the lines in each pumping cycle. Therefore, such lines are particularly preferably as short as possible, for example not more than 10 centimeters, to design. However, the control of the individual pumps is of course again according to the pattern described above, according to which there is a phase offset PHI of 180 ° between each successive pumping chambers.

According to a further preferred embodiment, the device is designed so that information about the delivery state during operation can be obtained. For this purpose, the device comprises the following features:

At least one of the actuators is designed to be switched off. For this purpose, a circuit arrangement may preferably be provided, which not only allows the frequency-controlled operation of the actuator, but also has a control possibility, which allows a temporary or permanent exposure of at least one or more actuators during operation. In this case, the exposure signal can, for example, "migrate" in the direction of flow from the first actuator, so that only one, but not always, the same actuator is temporarily stopped.

A circuit arrangement is provided, which makes it possible to detect the shape change of the actuator produced by means of fluid pressure at the at least one deactivated actuator during operation of the device with one or more non-deactivated actuators. In other words, the circuit arrangement allows a read-out of the "passive" operation, ie without drive energy, caused changes in shape of the at least one deactivated actuator. In the exemplary case of piezo actuators, a voltage is induced by an externally applied change in shape, for example by a change in pressure in the pumping chamber, which voltage can then be conducted to the outside via suitable electrical leads and measured there. As lines, the already existing lines which are necessary for the operation of the respective actuator can be used with particular preference. The circuit provided for the readability of the shape changes according to the invention is particularly preferably integrated into the circuit for activating and temporarily switching off the actuator or actuators and, if desired, equipped with an interface to a control panel, a computer or a radio transmitter.

In the following, in particular, the method according to the invention will be described in more detail, which is particularly preferably carried out together with the device according to the invention.

Accordingly, the method is suitable for the bubble-tolerant and efficient delivery of a fluid, wherein it advantageously cooperates with a device which:

- consists of a number of N ≥ 2 pumping chambers with N separate chamber volumes, each of which is independently variable from the other, wherein the volume changes of the pumping chambers substantially each periodically run at a substantially same frequency f;

N comprises actuators for changing the respective chamber volumes;

also provides one or more valves for defining the pumping direction;

and finally comprising a common inlet and outlet.

The N pumping chambers are arranged serially one behind the other. The inventive process requires that the shapes of the periods of changes in volume of all the pump chambers are substantially ^"are identical, and that the pump chambers are controlled in such a way so that there is between the volume change of the chamber volume between two successive pumping chambers an ideal phase offset PHI of about 180 °.

According to a preferred embodiment, the method according to the invention cooperates with a device for which N = 2, that is, two

Pumping chambers consists. The phase offset between the first and the second pumping chamber is 180 ° in accordance with the method according to the invention.

According to a preferred embodiment, an actual phase offset PHI * does not deviate more than ± 7% and in a particularly preferred embodiment not more than ± 3% from the ideal phase offset PHI. As a general rule The rule is that smaller deviations from the ideal value are always to be preferred.

The process according to the invention is particularly preferably suitable for conveying fluids which are selected from the group of liquids, gases and liquid-gas mixtures, the process being in the case of a mixture both dissolved in the liquid and as Bubbles present gas fractions is suitable.

Preferably, the change in the volume of each pumping chamber takes place in accordance with a rectangular curve. In the case of electrically driven actuators, e.g. Piezoactuators, this means that their control is ideally done with mutually phase-shifted square-wave voltages. By driving by square-wave voltage, the actuator moves accordingly, resulting in the optimal case of an approximately rectangular running cyclic volume change of the respective pumping chamber. In the event that the allocation between actuation of the actuator and volume change of the pumping chamber is not proportional, appropriate correction factors or functions can be used.

According to a preferred embodiment of the method according to the invention, the rising and / or falling edge of the square-wave voltage / curve is rounded in such a way that cavitation effects in the pumping chamber caused by insufficient chamber pressure are avoided. Experiments have shown that If the actuator relaxes too quickly, a negative pressure can develop in the pumping chamber which leads to spontaneous gas bubble formation, since the boiling point in a fluid depends on its pressure state and also drops sharply at lower pressures, in extreme cases up to room temperature. The subsequent collapse of the cavitation gas bubbles during normalization of the pressure results in strong pressure waves, which can lead to significant material damage in the event of permanent occurrence and should therefore be avoided.

According to a further embodiment of the method according to the invention, the frequencies f of the volume changes of successive pumping chambers can have a difference Δ temporarily or continuously. This difference is to be regarded as a deliberate, deliberately set difference in the frequency of the individual chambers. If, for example, the difference is just 1 Hz at an operating frequency of 100 Hz, the differing chamber again reaches the same phase offset after 100 cycles as at the beginning of the induced one

Frequency change. As could be shown by experiments, this temporary introduction of a so-called "beating" is particularly well suited for dispensing gas bubbles which otherwise can not be released from the fluidic channels of the device, depending on the specific design of the device and the physical properties of the fluid For example, the difference Δ may be different in magnitude and different in length in order to obtain an optimum result. According to a particularly preferred embodiment of the method, the difference Δ is preferably less than 1% of the frequency f and particularly preferably less than 0.1% of the frequency f.

According to a preferred embodiment of the method according to the invention can also be obtained with this information about the delivery state during operation. This requires at least one of the following steps to be taken; most preferably, all of the following steps must be performed sequentially:

(1) Temporary or continuous shutdown of one or more actuators. This is particularly useful if either the actuator itself offers the opportunity to serve as a sensor for pressure changes in the respective pumping chamber, or if a suitable pressure sensor is otherwise available.

(2) Detecting the shape change (s) produced by the fluid pressure on the actuator (s). This is particularly preferably possible by means of piezoactuators, which in turn generate a voltage in "passive" operation, ie without application of an electrical voltage, as soon as they undergo a change in shape. Under certain conditions, the pressure, the change in shape caused thereby and the resulting voltage also proportional to each other, so that a piezoelectric actuator can be converted as a simple pressure sensor. (3) Comparison of the detected shape changes with set values resulting from proper operation. If values, for example voltage values, are known from an operation without disturbance, the magnitude of the disturbance can be deduced by a simple, qualitative comparison on the existence of a disturbance, or by quantitative comparison in a first approximation.

Depending on the embodiment, the fault detection can only be temporarily assumed by one or more actuators, or one or more actuators can be permanently converted as fault sensors. Similarly, the reading of one or more separately introduced and unspecified here sensors can temporarily serve to detect malfunctions.

Advantageously, however, the embodiment according to which the already existing actuators are temporarily used as fault sensors.

According to a particularly preferred embodiment of the method according to the invention, upon detection of a disturbance to remedy the same temporarily a change in operation as described above is triggered, ie, there is generated a beat according to the invention, with which the disturbance can be corrected again, provided that they occur an otherwise non-removable gas bubble was caused. LIST OF FIGURES

Fig. 1: exploded view of the device according to the invention

Fig. 2: optimized curve for control or volume change

Fig. 3: Curve course at 180 ° offset phases; Duty cycle = 1: 1

Fig. 4: Curve course at 180 ° offset phases; Duty cycle ≠ 1: 1

figure description

1 shows an exploded view of a particularly preferred embodiment of the device 1 according to the invention. This consists of a layer-like structure 1, which in the case illustrated comprises two pumping chambers 2.

According to FIG. 1, the structure 1 consists in detail of the following components:

- A Boden.element 7, which is particularly preferably made of plastic. The bottom element comprises ^■ a recess 7 ', in which all the following components on or be placed. The bottom element preferably also includes the inlet 4 and outlet 5 necessary for conveying the fluid, which, as shown here, for example each formed as a tubular connection. Of course, other, adapted to the particular application connector types are conceivable. Likewise, the bottom element comprises parts of the necessary for the valves 3 fluid channels, preferably in

Injection molding process and thus produced in the same operation as the floor element itself.

In addition, the bottom element carries as an assembly aid raised parts of the same 1 '' in the form of geometric features, which are arranged such that they cooperate with the recesses of the mounting aid I ¹ ''. Thus, the installation of the following components such as a valve sheet 8 can be done only in one way, so that incorrect assembly is largely excluded.

- A valve sheet 8, which carries the moving parts of the valves 3 and is inserted into the bottom element. In the illustrated form, the valve film comprises the moving parts of both the intake valves 3 'of each pumping chamber and the moving parts of the respective exhaust valves 3 ". Furthermore, the valve film also includes the recesses of the mounting aid 1 '' ', which serve a faultless installation of the valve film.

- An intermediate layer 9, which is preferably made of a plastic. This is designed so that it can be inserted into the recess 7 'of the bottom element 7. In the center of each pumping chamber 2, which arises in each case by a depression in the intermediate layer, there is one each Opening 9 ', through which fluid in the pumping chamber on or can flow out of this again.

A protective layer 10, which is applied to the intermediate layer and thus closes the pumping chamber fluidically upwards. Accordingly, the protective layer must be firmly connected to the intermediate layer so that fluid can not flow out or over either at its circumference or in the area between the pumping chambers. For this purpose, as already mentioned, preferably laser transmission welding is used. Alternative manufacturing methods are gluing, ultrasonic welding, or mechanical clamping of the respective components.

- Two actuators 6, which are designed in the illustrated embodiment as a disk-shaped piezo actuators. Each of the actuators is geometrically adapted to the underlying pump chamber 2 and carries for electrical contacting corresponding electrodes 6 '. Connected to these is an electrical connection 6 '', which can be guided out of the housing of the device 1, and which holds a sufficient number of individual cores for connecting each actuator.

A cover element 11 which serves to close the housing 1 of the device 1, which essentially consists of the bottom element 7. Preferably, the cover element is made of plastic and configured connectable to the bottom element by means of laser transmission welding. FIG. 2 shows a diagram in which the abscissa represents the time on which the ordinate represents the actuator voltage U (hereinafter referred to as the "control curve") and / or the volume of a pumping chamber (referred to below as the "chamber volume curve"). The illustrated amount of time corresponds to just one period, ie the time necessary for a single pumping cycle of a pumping chamber.

The dashed line shows an ideal rectangle curve. According to the invention, both the rising flank A and the falling flank B of this curve can be rounded, so that a curve corresponding to the solid line results, which represents the optimized curve. As described above, this rounding serves to avoid pressure change peaks, which can lead to undesired cavitation bubble formation. The exact optimized shapes of the fillets must be determined depending on the precise geometric design of the pump chambers, the fluid channels and the height of the operating pressures. This can be done for example by calculation, simulation and / or the execution of test series. The form shown here is therefore to be understood only as a symbol and does not correspond to the actual, optimal form of the control or chamber volume curve.

FIG. 3 shows a diagram with the same

Likewise, it shows the solid line of Figure 2, which shows the optimized curve sales of the drive or Kaitunervolumenskurve reproduces. In addition, as a dotted line, a PHI = 180 ° out of phase curve is plotted showing the drive curve of the actuator following that which is driven according to the solid line. In the variant shown here, the lifting and lowering phases of an actuator, the so-called duty cycle, are approximately the same length, which is why the almost mirrored shape of the dotted line results (duty cycle 1: 1). In cases where that

Duty cycle is not the same size, resulting in images in which the wake of the second drive curve does not correspond accordingly as a reflection of the first.

This case is shown in FIG. Here is the

Phase response PHI again 180 °, but the duty cycle is approximately 1: 3 (the period at which the curve shows a high value is much shorter than the part at which it is close to zero).

Method of conveying a fluid and micropump therefor

LIST OF REFERENCES 1 Device for conveying a fluid

2 pumping chamber

3 valve

3 'inlet valve

3 '' outlet valve 4 inlet

5 outlet

6 actuator, piezomembrane actuator 6 'electrode

6 '' electrical connection 7 floor element

T recess

1 '' raised TeiJ. the mounting aid

~ l '''recesses of the assembly aid 8 valve foil

9 intermediate layer 9 'openings

10 protective layer

11 cover element

A rising edge

B falling edge

Claims

Bartels Mikrotecnik Gmbh Method of conveying a fluid and micropump therefor. Claims

A device for the bubble-tolerant delivery of a fluid, comprising

- a number of N ≥ 2 pumping chambers (2) with N separate chamber volumes, each of which is independently variable from one another, the volume changes of the pumping chambers (2) being substantially periodically each at a substantially equal frequency f; - N actuators to change the respective chamber volumes;

- valves (3) for determining the pumping direction;

a common inlet (4) and outlet (5); characterized in that the N pumping chambers (2) are arranged serially one behind the other, and that the forms of the periods of volume changes of all the pumping chambers (2) are substantially identical, and that between the volume change of the chamber volume of two successive pumping chambers (2) is an ideal phase offset PHI of about 180 ° exists.

2. Apparatus according to claim 1, characterized in that N = 2.

3. Device according to one of the preceding claims, characterized in that an actual phase offset PHI * preferably not more than, + 7% and more preferably not more than ± 3% deviates from the ideal phase offset PHI.

4. Device according to one of the preceding claims, characterized in that the fluid is a liquid, a gas, or a liquid-gas mixture, in which the gas in the liquid ^• dissolved and / or may be in the form of bubbles.

5. Device according to one of the preceding claims, characterized in that each pumping chamber (2) preferably at least one own inlet and / or at least one outlet valve and more preferably two own inlet valves (3 ') and two separate outlet valves (3' ') and that the valves are arranged and configured such that the directional changes in the fluid flow caused by them are minimized.

6. Device according to one of the preceding claims, characterized in that it comprises the change of the respective chamber volumes Piezomembranaktuatoren (6).

7. Device according to one of the preceding claims, characterized in that all in contact with the

Fluid standing components made of polyphenylsulfone (PPSU) exist.

8. Device according to one of the preceding claims, characterized in that all together connecting components are connected by laser transmission welding.

9. Device according to one of the preceding claims, characterized in that the components are designed such that a faulty mounting is largely excluded.

10. Device according to one of the preceding claims, characterized in that for the production of a single pumping chamber (2) necessary components, in particular the or the valves (3) and the actuator (6) against which for the preparation of another pumping chamber (2 ) components of the same device are essentially interchangeable or designed identically with these.

11. Device according to one of the preceding claims, characterized in that it comprises the following components:

- A bottom element (7) with a recess (7 '), as well as in the recess (7') into the leading inlet (4) and one of the recess

(7 ') out leading outlet (5), and also between the inlet and the outlet in the same plane fluid structures for guiding the fluid to be conveyed to the valves (3, 3', 3 '') and for the fluidic connection of both

Pumping chambers (2) and for connection to the inlet (4) and the outlet (5); - A valve film (8) in the recess (7 ') can be inserted and the movable parts of the valves (3, 3', 3 ") carries;

- An intermediate layer (9) above the valve film (8) into the recess (7 ') can be inserted and openings (9'), which form the non-moving parts of the valves (3, 3 ', 3' ');

- A protective layer (10) which above the intermediate layer (9) into the recess (7 ') can be inserted and the ^{ι of} the intermediate layer (9) forms two lying in a plane cavities, which serve as pumping chambers (2);

- Two actuators (6) with electrodes (6 ') and electrical connections (6' '), each actuator (6) is arranged in each case congruent with the underlying pumping chamber (2), and wherein by operation of the actuator (6) Chamber volume of each under the actuator (6) lying pumping chamber (2) is variable; a cover element (11) whose outer contours essentially correspond to those of the floor element (7) and which can be placed on the floor element (7) and which, after being connected to the floor element (7), closes the recess (7 ') in such a way that located in their interior

Components are protected from external influences; and in the bottom element (7), intermediate layer (9) and cover element (11) can be connected to one another in a fluid-tight manner.

12. Device according to one of the preceding claims, characterized in that the same by a serial arrangement of. N separate, in each case only one pump chamber (2) comprising individual pumps is formed, which are designed to be connected to each other by means of fluidic lines.

13. Device according to one of claims 1 to 12, wherein: the device is designed such that information about the conveying state during operation -derart can be obtained, the device for this purpose comprises the following features

- At least one of the actuators (6) is designed to be switched off; a circuit arrangement is provided which makes it possible to detect the changes in shape of the actuator (6) caused by the fluid pressure on a deactivated actuator (6) during operation of the device with an actuator (6) not switched off.

14. A method for the bubble-tolerant delivery of a fluid, comprising:

- a number of N ≥ 2 pumping chambers (2) with N separate chamber volumes, each of which is independently variable from the other, with the volume changes of the pumping chambers (2) substantially periodically each having a substantially equal frequency f ; - N actuators (6) for changing the respective chamber volumes;

- valves (3) for determining the pumping direction;

a common inlet (4) and outlet (5); wherein the N pumping chambers (2) are arranged serially one behind the other, and the forms of the periods of volume changes of all pumping chambers (2) are substantially identical, and the pumping chambers (2) are controlled so that between the volume change of the chamber volume of two successive pumping chambers ( 2) there is an ideal phase shift PHI of approximately 180 °.

15. The method according to claim 14, characterized in that N = 2.

16. The method according to any one of claims 14 and 15, characterized in that an actual phase offset PHI * preferably not more than ± 7% and more preferably not more than + 3% from the ideal phase offset PHI deviates.

17. A method for conveying fluids according to claim 4, characterized in that by using the method, a device according to one of the preceding claims 1 to 12 is used.

18. The method according to claim 14, characterized in that the actuation of the actuators (6) in

Essentially done with mutually phase-shifted square voltages.

19. The method according to claim 18, characterized in that the rising and / or falling edge of the square-wave voltage / curve is rounded in such a way that caused by low chamber pressure cavitation effects in the pumping chamber (2) can be avoided.

20. The method according to any one of claims 14 to 19, characterized in that the frequencies f of the volume changes of successive pumping chambers (2) temporarily or continuously have a difference Δ.

21. The method according to claim 20, characterized in that the difference Δ is preferably less than 1% of the frequency f and more preferably less than 0.1% of the frequency f.

22. The method according to any one of claims 14 to 21, characterized in that information about the state of conveyance during operation are obtained such that at least one of the following steps and preferably all steps are carried out sequentially or are:

- Temporary or continuous shutdown of one or more actuators (6);

Detecting the fluid pressure generated by the actuator (s) (6)

Shape changes;

- Comparison of the detected changes in shape with set values resulting from proper operation.

23. The method according to claim 22, characterized in that upon detection of a fault to remedy the same temporarily a change in the operation is triggered according to claim 20.