WO1992021883A1 - Microminiaturized electrostatic pump and device for determining the flow rate of a gas or liquid - Google Patents

Microminiaturized electrostatic pump and device for determining the flow rate of a gas or liquid Download PDF

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Publication number
WO1992021883A1
WO1992021883A1 PCT/DE1992/000409 DE9200409W WO9221883A1 WO 1992021883 A1 WO1992021883 A1 WO 1992021883A1 DE 9200409 W DE9200409 W DE 9200409W WO 9221883 A1 WO9221883 A1 WO 9221883A1
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Application
Patent type
Prior art keywords
electrodes
pump
characterized
flow
carrier body
Prior art date
Application number
PCT/DE1992/000409
Other languages
German (de)
French (fr)
Inventor
Klaus Hofmann
Axel Richter
Hermann Sandmaier
Andreas Plettner
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04FPUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F99/00Subject matter not provided for in other groups of this subclass
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B05SPRAYING OR ATOMISING IN GENERAL; APPLYING LIQUIDS OR OTHER FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05BSPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/16Arrangements for supplying liquids or other fluent material
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow
    • G01F1/704Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through the meter in a continuous flow using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter
    • G01F1/708Measuring the time taken to traverse a fixed distance
    • G01F1/7088Measuring the time taken to traverse a fixed distance using electrical loaded particles as tracers
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/18Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02NELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N11/00Generators or motors not provided for elsewhere; Alleged perpetua mobilia obtained by electric or magnetic means
    • H02N11/006Motors

Abstract

A microminiaturized electrostatic pump has at least two spaced apart electrodes (10', 11') and one electrode supporting body (2'). A device for determining the flow rate of a gas or liquid also has at least two spaced apart electrodes (10', 11') and one electrode supporting body (2'). In order to simplify the production of such a device or pump, both electrodes (10', 11') are arranged on the main surfaces of a common electrode supporting body (2') that is insulated from at least one of the two electrodes (10', 11') and is provided with a throughflow opening that is substantially vertical to its main surfaces.

Description

A microminiaturized electrostatic pump and apparatus for determining the flow velocity of a gas or a liquid

description

The present invention relates to a microminiaturized electrostatic pump having at least two in a pum¬ to penden, substantially non-conductive fluffiness or in a to be pumped, essentially non-conductive gas an¬ parent, mutually substantially spaced apart in the direction Pumpströmungs¬ electrodes, which can be pressurized stream with a potential for injecting or accelerating a trodes between the Elek¬ by the liquid or gas flowing Ionen¬ trodenträgerkörper and with at least one Elek¬, according to the preamble of the patent claim l.

The invention further relates to a device for determining the flow velocity of a gas or a liquid with two from each other in the gas or in the liquid substantially beabstande¬ in the flow direction th electrodes, which are so acted upon by a voltage, that an electrode ions in the gas or sigkeit injected into the Flüs¬ whose charge is at least partly transferred to the other electrode from which will be abge¬ a measuring current, comprising a generator for generating a time varying voltage signal, which can be applied to the electrodes, a current detector for detecting a change of the voltage Me߬ caused by the change in current, and an evaluation device for measuring the Zeit¬ duration between the change in voltage and the change of the measuring current and for determining the Strömungsgeschwindig¬ ness of the gas and of the fluid based on the measured Zeit¬ duration, according to the preamble of Claim 2. In particular, the present invention is concerned with a device for measuring the flow tubes in low volume at low flow rates.

From the German Patent DE 39 25 749 Cl of the Applicant a generic diagram microminiaturized elektrosta¬ pump is already known. This known pump comprises two superimposed in the pump flow direction Halbleiter¬ body, for example, are gitterfδrmig or web-shaped configuration for integrally forming electrodes as part of the semiconductor body. The two Elektroden¬ support body need to ensure a good function of elektrosta¬ tables pump anein¬ with high precision are joined to the other so that the respective electrode web structures or opposite electrode grid structures with a small distance in the pump flow direction. In the joining of the two semiconductor bodies, can not always be ruled out that tolerances resulting from the mutual alignment of the semiconductor body, as compared with the tolerances of the electrode structures formed body within the Elektrodenträger¬ by lithographic process are comparatively large. By requiring the mutual alignment of the two electrode support body further miniaturization of the pump limits are set so that this known pump is not able to satisfy constantly voll¬ despite their outstanding properties in terms of the er¬ ford variable costs in their manufacture.

Further examples of long been known electrostatic pumps are 44 63 798 A for example known from the US 46 34 057 A, from the US 33 98 685 A as well as from the US for some time. These known elektrostati¬'s pumps have also two substantially Pump¬ in the flow direction of spaced electrodes, which are flowed around by the liquid being pumped or by the gas to be pumped. Between the electrodes a DC voltage or an AC voltage is applied 'to effect ion injection into the liquid or gas. The processes known from the publications mentioned electrostatic pumps typically consist häusekörper of a tubular Ge, which is flowed through by the fluid or the gas in the axial direction and having a first, centrally arranged ke- gelspitzför strength electrode customarily, in a threadedly adjustable axial distance is disposed from the counter electrode which is constructed substantially as a nozzle with a frusto-conical recess. Ty¬ pisch legally pass the housing body of such pumps made of plastic. The electrodes are usually made of metal and screwed into the plastic housing. Be¬ known electrostatic pumps of the type described er¬ not only require a relatively high operating voltage in the order of 15 kV to 40 kV, but also a complex adjustment for setting the appropriate Elektro¬ denabstandes. Because of their relatively complex structure known from the publications mentioned pumps can not be miniaturized.

There are a variety of devices for flow measurement Durch¬ known where to find the different physical principles apply. In one of the known devices, a laser Doppler anemometer is used. While this enables measurements down to the Be¬ reaching the speed of 1 mm / sec, but requires a very high cost. For all other known Vorrichtun¬ gen but it is possible speeds with large percentage Meßungenauig- to identify small volume flows with flow rates below 100 ml / h. Most of the known measuring methods fail even completely in the measurement of flow rates in the range of microliters per minute.

The technical publication Theory of electro hydrodynamic flow meters; Yantovskii, EI; Apple-tree, MS; Petrichenko, NA; Magneto Hydro Dynamics (USA) (July-Sept. 1984) vol. 20, no. 3; p. 328-31; Translation of: Gidrodin Magn.. (USSR) an apparatus for electro-hydrodynamic flow measurements are already known. In the known device lie¬ in one of the with respect to its Strömungsgeschwindig¬ ness gen gas to be measured or of the liquid flowing through tube concerned three electrodes which are uniformly arranged beab¬ standet from each other in the flow direction. The average of the three electrodes is applied to such a Poten¬ tial that they injected ion ing into the gas or Flüs¬. The ab¬ given from the two outer electrodes comprise a current measuring currents of bipolar Leit¬ skill, comprising the mutual, opposite movement of equal amounts of charge carriers opposite Vorzei¬ Chen, and a Konvektionsström. As the current of the bipolar conductivity is independent of the speed Strömungsge¬, the latter convection is dependent on the measured flow rate. The output from the electrode currents are supplied to the separating these portions of a bridge circuit whose voltage output Span¬ the asymmetry of the current supplied to the bridge currents and thus reproduces the liberated on the proportion conductive bipolar flow convection. Due to the height of the measured voltage will speed up the flow velocities and thus draw conclusions about the flow rate. Even small faults lead to a considerable Ver¬ forgery of the measured flow rate, so that the just described generic method and generic device are not suitable by the prior art to detect small flows ness high Genauig¬.

In the apparatus for determining the Strömungsgeschwindig¬ a gas or a liquid according to the ness Patentan¬ Application P 40 27 704.6-52 it is necessary to position the two electrodes closely against each other. This prepares production technical difficulties.

From the German Patent DE 39 25 749 Cl of the Applicant a microminiaturized electrostatic pump is already known. This known pump comprises two superposed in Pumpströmungs- directional semiconductor body, which are configured, for example gitterformig or web-shaped body for integrally forming electrodes as part of the Halbleiter¬. The two electrode carrier body must, in order to ensure a good function of the electrostatic pump, are joined to each other with high accuracy, so that the respective electrodes web structures or electrode grid structures are opposed at a short distance in the pump flow direction. In the Aneinander¬ of the semiconductor body paste can not be closed always ausge¬ that tolerances in the mutual Aus¬ direction of the semiconductor bodies are formed, compared with the tolerances of the electrode structures which are formed by litho¬ graphical procedures within the electrode carrier body, comparatively large are. By Er¬ fordernis the mutual alignment of the two Elektro¬ denträgerkörper further miniaturization of the pump limits are set so that this known pump is not able to fully satisfy despite their outstanding properties in terms of the erforder¬ union effort in their production.

Starting from the above described prior art, the present invention is therefore based on the object, a microminiaturized electrostatic pump of the type called ge develop so that they can be more easily herge¬ represents and is further miniaturized.

This object is solved by a microminiature elektro¬ static pump having the features specified in patent claim 1.

Starting from this prior art, the invention is further the object of developing a device for determining the flow velocity of a gas or a liquid of the kind mentioned so that its manufacture is facilitated. This object is achieved by a device according to patent claim. 2

The invention is based on the recognition that the occurring in the prior art for microminiature elektrostati¬ rule pumps or Strömungsgeschwindigkeitsmeßvorrichtungen Justageproblem for the electrodes can be sgeräumt au¬ characterized in that the electrodes no longer je¬ weils associated with an electrode support body, the so¬ then is th auszurich¬ relative to the other electrode carrier body, but that both electrode surfaces at the two Haupt¬ a single electrode support body are arranged, wherein the electrode support body is at least isolated from one of the two electrodes and at least one substantially er¬ vertical to its major surfaces stretching throughflow opening having.

In the inventive microminiature elektrosta¬ tables Strömungsgeschwindigkeitsmeßvorrichtung pump or the electrode spacing is determined by the vertical extension of the electrode support body, whereby the accuracy of the mutual arrangement of the two electrodes corresponding to the high precision that can be achieved with the use of lithographic methods.

Preferred embodiments of the pump of the invention and the Strömungsgeschwindigkeitsmeßvorrichtung are given in the subclaims.

In the inventive device the duration of an injected in a liquid or in a gas depends Ionen¬ front, the processing between two substantially in Strömungsrich¬ moved spaced apart electrodes in a elektri¬'s field from the injecting electrode to a receiving electrode from the velocity of the moving from between the electrodes or the gas moving between the electrodes liquid so that, by detecting the time difference of the change of Me߬ the flow velocity of the gas or Flüs¬ stream after changing the voltage applied to the electrodes Span¬ sigkeit can be determined.

flow velocities, a particularly accurate measurement of flow rates or Strö¬ is achieved when Laufzeitdif- conferences between two generated in the gas or in the liquid ion fronts in the opposite direction once with the flow and one against the flow by the gas or liquid run, be used as a basis for determining the flow velocity of the gas or liquid.

Embodiments of the invention will be explained in more detail with reference to the accompanying drawings. Show it:

Fig. 1 shows a first embodiment of a measuring device;

Fig. 2 shows a second embodiment of the measuring device;

Fig. 3 is a block diagram of signals for determining the flow velocity based on the output measuring device shown in Figure 1.

Figure 4 is another block diagram for determining the flow rate due to the output from the measuring device shown in Figure 2 signals..;

5 is a graph of current density as a function of time.

6 is a diagram of the space charge density as a function of the distance. 7 is a graph of electric field strength in dependence on the distance.

8 is a diagram of the current in function of time.

9 is a diagram of the calculated time point of the maximum current in dependence on the flow velocity Strö¬.

10 is a diagram of the measured time point of the maximum current in dependence on the flow velocity Strö¬.

Fig. 11 is a diagram of the time difference of the maximum current due to two opposite lau¬ fender ion fronts in a gas or in a liquid as a function of the absolute flow velocity.

Figs. 12 to cross-sectional views of a first to

16 schwindigkeitsmeßvorrichtung fifth embodiment of an essential part of the invention or Strömungsge¬ pump;

Figs. 17 to plan views of a sixth to ninth training

keitsmeßvorrichtung guide die 20 of an essential part of the invention or Strömungsgeschwindig¬ pump;

Fig 21, 22 are perspective sectional views of a tenth and eleventh embodiment of an essential part of the invention or Strömungsgeschwindigkeitsmeßvorrichtung pump. and

Figs. 23 to top views of a twelfth to fifteenth

26 embodiment of the present invention or Strömungsgeschwindigkeitsmeßvorrichtung pump;

The flowmeter shown in Fig. L, which is indicated in its entirety by the reference numeral 1, comprises a flow-through of a fluid pipe, in the direction perpendicular to the flow direction a plurality of interconnected leitfä¬ hig associated injector electrodes 3 and spaced therefrom in Strö¬ flow direction and likewise perpendicular to the flow direction of which a plurality of conductive also interconnected collector electrodes 4 are seen vor¬. a Spannungs¬ pulse U (t) can be connected to two connections 5, 6 between the two electrodes 3, 4 are applied so that an ion front is injected into the fluid. The resulting transient current j (t) generated at a Me߬ resistance R a to the current j (t) proportional Meßspan¬ voltage Um (t), which can be further processed as a measuring signal for the travel time measurement, which will be explained later.

In FIG. 2, another embodiment of a Durchflußme߬ shown device, the sign in its entirety by the reference numeral 10 designates Bezugs¬ is. This also comprises a tube 12, a plurality of arranged perpendicular to the flow direction and conductively interconnected Injektor¬ electrode 13, a first plurality of counter to the Strö¬ flow direction to the injector electrodes 13 spaced Kollektroelektroden 14a, and a second plurality of flow direction to the injector electrodes 13 arranged collector electrode 14b. Both sets of collector electrodes each extend perpendicular to the flow direction and are conductively connected to each other.

A voltage pulse U (t) can be connected to terminals 15, 16 are applied and results in a flow direction in ausbrei¬ Tenden and a counter to the flow direction of the fluid propagating ion front. Each entstehen¬ the transient currents j, and j 2 (t) to generate Wider¬ stands Rl and R2, respectively trodes between the Kollektorelek- 14a, 14b and one of the terminals 15 are connected to the currents proportional voltages U, ( t) and U 2 (t), which further verar¬ than measuring signals for the duration of measurements can be beitet. The flow rate or velocity Strömungsge¬ can, as will be explained later, are derived from the running time difference.

Fig. 3 is a block diagram of a circuit for determining the flow rate or flow rate for the embodiment shown in Fig. 1 flowmeter. is ge shows as in Fig. 3, the circuit comprises a clock generator 20 which supplies a clock signal to a counter 21. A Impulsgenera¬ gate 22, the pulses for generating the aforementioned Spannungsim¬ U (t) is used, on the output side to the Durchflußme߬ device 1 is connected, as has been explained with reference to FIG. 1. By generating the voltage pulse of the pulse generator 22 to the counter 21 to a start signal, whereupon the counter with him zuge¬ supplied from the clock pulse generator 20 starts to count clock signal. The output signal m (t) of the flow measuring device 1 is supplied to a peak detector 23 which generates a stop signal upon detection of the maximum of the voltage signal Um (t) with which the counter is stopped 21st , The flow rate or the flow velocity can be made of the count value is set as spä¬ ter, due to a predetermined order for the respective Meßan¬ assignment, are determined by table-like association. This cycle can repeat continuously fen ablau¬ after resetting the counter and detector.

Fig. 4 is a block diagram of a circuit for determining the flow rate or flow velocity of a flow measurement device 10, as shown in Fig. 2. This circuit comprises a clock generator 24 and the clock generator 24 downstream counter 25. Further, the circuit comprises a pulse generator 26 for generating the voltage pulse U (t), wherein the flow measuring device 10 (see Fig. Fig. 2) is supplied. The two measured voltages U (t) and U 2 (t) of the flow measuring device 10, which through the resistors Rl and fall R2, are supplied to a first and a second peak detector 27. 28, the output signals via an exclusive OR gate 29 are linked to form a start-stop signal for the counter 25th For the skilled person it is obvious that the counter 25 of this circuit zenwerte the time difference between detection of the Spit¬ by the peak detector 27, detects the 28th Die-- ser cycle can door repeated continuously proceed after resetting the counter and the Detek¬.

Subsequently, the abhän¬ on the flow rate-independent timing of the measurement current for the device shown in Fig. 1 structure of the flowmeter l is derived. In the derivation it is assumed that the liquid senk¬ right to the electrodes 3, 4 flows. For example, reference may be made an¬ that the liquid through the formed by the electrodes 3, 4 grid means of an external pump (not shown) is forced. Further, assume that the liquid has a constant time and location of flow, ie, that through the (not dargestell¬ te) external pump pressure generated is much greater than the pressure generated by the injecting electrodes 3 themselves, and that no turbulence within the liquid auftre¬ th Based on this assumption, we obtain the following deviations glei.:

j c (x, t) = μ g (x, t) E (x, t) + v g (x, t) (l)

δ j c (x, t) δ q (x, t)

(2)

S x δ t

δ E (X, t) q (x, t) = e 0 E r (3) δ x E (X, t) j (t) = j c (x, t) + e 0 e r (4) ό * t

Describe herein t is time, x the location between the two grids, j c the line current, μ the ion mobility, the charge E q is the electric field strength, v the Strömungsge¬ velocity of the fluid and e is 0 or e r absolute or relative dielectric constant.

As initial conditions to consider:

E (x, 0) = U / d is 0 <x <d at time t = 0 (5) q (x, 0) = 0

At the same time the following conditions must be observed:

r

JE (x, t) dx = U (6)

q (0, t) = g-, (7)

The second equation describes the intensity of the injected charge at the electrode injecting q 0th This value is (for example, capitalization be metallized, geometry, surface roughness) of both the nature of the electrode and on the liquid used dependent.

By introducing standardized sizes

Figure imgf000015_0002

can be obtained dimensionless, painted variables.

Figure imgf000015_0003

For the dimensionless current density is obtained releasable only by numerical integration term

r j '(t) =%

Figure imgf000015_0001
+ V '' J q '(x', t ') dx'

(8th)

If a voltage of 100 V applied to grids with a spacing of 0.01 cm and assuming an ion mobility 10-4 cm2 / Vs, then corresponds to v 7 = 1 Geschwin¬ a speed of 1 cm / s. In a grid area of 1 mm x 1 mm, this corresponds to a flow rate of 0.01 cm 3 / sec and 0.6 ml / min.

Now, the parameters ion mobility and space charge density at the injecting electrode for a specific measuring arrangement once established, it can be with the help of above equation to determine the flow rate and thus the flow rate of a fluid. Alternatively, of course, the volume flow can also be determined, are measured at a known flow and used as Re¬ conference when the running time measurements.

To further illustrate the process of the invention are described below with reference to FIGS. 5 - 8 Dia¬ programs explained, the fronts the behavior of the injected fluid Ionen¬ in a stationary (speed v = 0) ver¬ clear before with reference to Figures . 9 and 10, the influences of the fluid velocity on the measured Zeit¬ point of the maximum current or to the measured Zeitdiffe¬ ence between the times of detection of maximum values ​​Strom¬ will be explained.

Fig. 5 shows the time course of the current density j 'in¬ nerhalb of the fluid, for example, in the case of Durchflu߬ measuring apparatus 1 of FIG. 1 after applying a Spannungs¬ jump to the electrodes 3, 4 in the event of a vanishing velocity v = 0. The axes of the Diagrammdar¬ position of FIG. 5 are mized nor¬ accordance with the above derivation. The voltage jump leads to the injection of ions into the fluid. The vertical axis indicates the current density j 'at the injecting electrode 3 in function of time, wherein as a parameter different space charge densities at the collector electrode 4 with the space charge densities of 0.1 to 20.0. The voltage jump leads after the injection of ions into the fluid at the location of injecting electrode 3 to an acceleration of the ions in the electric field in the direction of the collector electrode 4. The measured Strom¬ density reaches a maximum at time t 0, which of the arrival the first carrier is produced on the collector electrode. 4

Fig. 6 shows the reference name in Fig. 5 explained case, the local profile of the space charge density, starting from the injector electrode 3 at the location x '= 0 to the place of Kol¬ lecturer electrode or counter electrode 4 at the location x / = l different union at unter¬ hours, 0.15, 0.30, 0.45, 0.60, 0.75, 0.85 after switching on the voltage. Clearly here is the Fort¬ exceed the ion front to detect. The maximum of the current occurs after the impact of these ions front at the time t = 0.86 to the collector electrode. 4

Fig. 7 shows the corresponding course of the electric field strength E 'as a function of the normalized distance' also to the above time points.

Fig. 8 shows an operation performed at a practically realized Ausfüh¬ approximately example of FIG. 1 Measurement of Strom¬ course in function of time, wherein the fluid used in this test setup is deionized water. In Fig. 8 it is seen that the measured current exhibits a pronounced Ma¬ ximum called the drift time of the ions in the case of front also stationary at this diagram fluid (Geschwin¬ speed v = 0).

Fig. 9 now displays according to the detected above equation (8) the drift time t 0, ie the time between the application of the voltage jump U (t) and the detection of the maximum current as a function of the flow velocity of the fluid, in this diagrammatic representation, the injecting chamber is charge density ¬ To a l s parameters of the curves shown.

Fig. 10 shows the actually measured time of the maximum current as a function of the flow. As fluid is a 10 ~ 4 molar NaCl water solution was used.

In the process described now the relationship between the drift time and the flow rate for a given flow measuring device 1 can be determined, so that each time a corresponding measured drift Strömungs¬ velocity or flow rate can be assigned by means of a table. It should be emphasized that mit¬ means of a single test setup, the flow rate can be determined in both directions of flow so that t from the determination of the drift time can be derived 0 abge¬ not only the absolute flow velocity, but also their direction. However, changes of the electrochemical properties of the fluid during the measurement result in this test setup minor measurement inaccuracies since the drift time t 0 is dependent on the electrochemical properties of the fluid.

Such measurement inaccuracies are avoided by a measuring arrangement of the type shown in Fig. 2, wherein the two with the aid of the ion fronts in the opposite direction in the fluid injecting electrode pairs, the drift time t 0 so¬ well counter is determined to be even with the flow direction.

Fig. 11 shows the theoretically determined difference drift time is δ t 0 as a function of flow velocity. Due to this difference the influence of electrochemical Ver¬ changes of the fluid is almost eliminated, whereby an extremely high measuring accuracy is insbeson particular reached at very low flow rates.

In an arrangement known from DE 39 25 749 AI type of normalized value corresponds to v = 0.5 Strömungsge¬ a speed of 2 cm / s. In this Differenzmeßverfahren both two can oppositely disposed Injektorelek¬ trodes collector electrode pairs are used, as well as a single measuring cell, which is only three electrodes be¬ which a central injector 13 and two outer panels 14a, 14b includes.

It is also conceivable to perform such a differential measurement with a single electrode pair zu¬ is next applied in a first direction and then in a entgegen¬ other direction by a voltage pulse, so that initially an ion front drift in a first direction and then an ion front drift in a entgegenge¬ translated direction by the flowing fluid in their drift time is measured.

As shown in Fig. 12, comprises a first Ausführungs¬ form an inventive measuring device or pump Strömungsgeschwindigkeits¬ substantially a Elektro¬ denträgerkörper 2 ', which is enclosed by a housing 3. In the housing 3 'can be, a cast of a plastic housing having a peripheral area 4, for example,' 'encloses the electrode support body 2 firmly. The type of configuration of the housing 3 'as cast iron or as a formed of two halves screwed to an intermediate seal housing is at the discretion of the expert and needs for the purpose of constricting vorlie¬ invention no further explanation.

The electrode support body 2 'is made of a monocrystalline silicon semiconductor body having a (110) orientation -Kristall¬. For this purpose, first on the front and rear 5 ', 6' of the silicon semiconductor body 2 'by means of a usual in semiconductor technology process, a resistant layer to etching solutions, such as deposited silicon nitride. This serves as an etching stop mask and is first patterned on the front side by means of known photolithographic techniques. With an anisotropic etching process flow openings 7a ', 7b', 7c ', 7d', 7e 'are generated, which at a suitable orientation of the mask made of two parallel vertical and four to the front side 5' are planes inclined (111). Preferably, an 8-molar KOH solution is used as an etching solution, in order to suppress the formation of competing levels. When the desired depth of the through-flow openings achieved 7a 'to 7e', which can vary between 1 micron and a few 100 microns, an etching stop layer is formed on the front face 5 'applied open the backside etch stop layer and.

In a second etching step of the silicon body 2 'for generating a back surface recess 8' zurückge- is etched until the through-flow openings 7 'completely through the silicon body 2' rich.

After removal of the remaining residues of the etch stop layer, the entire electrode support body 2 'is to produce an insulation layer 9' openings in the area of ​​Durchstromungs¬ 7a 'to 7e' and at the front 5 'and the rear side 6' of the electrode support body 2 'is thermally oxidized.

A metallization is then both the front 5 'as well as on the rear side 6' is applied, which electrodes forms 10 ', 11'. These electrodes 10 ', 11' are ', 13' provided with terminals 12 which extend to the Außen¬ side of the housing 3 '.

In the sketched representation in accordance with FIG. 12, only a few are shown flow openings 7a 'to 7e'. The number of flow openings 7a 'to 7e' may be the size of a single throughflow opening between 0.1 micrometres and 1 millimeter can vary depending on the application between one and are a few thousand, wherein the width and length of a throughflow δffnung 7a 'to 7e' may be selected independent of each other.

For the skilled person it is obvious that the operation of the microminiaturized electrostatic pump according to the invention 1, a DC voltage or AC voltage connections to the An¬ 12, 13 is applied which is so high that it trittsδffnungen to a charge carrier injection in the area of ​​transit 7a to 7e occurs, the charge carriers through the flow openings 7a to 7e in the embodiment shown in Fig. 1 position in the vertical direction and thereby to entrain the pum¬ pende medium.

If the electrode support body 2 composed of a conductive material or a semiconductor material, this may be contacted via a terminal and applied with a potential. This allows the field gradients in the flow fields can be changed.

In the illustrated hereinafter modified Ausführungs¬ the form measuring apparatus according to the invention Strömungsgeschwindigkeits¬ or each pump is described only the relevant for the purposes of the invention structure of Elektrodenträgerkör¬ pers. The same or corresponding elements are designated Strömungsgeschwindigkeitsmeßvorrichtung sign with Bezugs¬ that match with the reference numbers used in Fig. 12 Be¬, so that a repeated description of similar or the same elements of the Strömungsgeschwindig¬ keitsmeßvorrichtung or may be omitted pump.

The second embodiment of the inventive Strömungsgeschwindigkeitsmeßvorrichtung or pump 1 shown in Fig. 13 'differs from the embodiment of FIG. 12 is substantially the fact that in these the Elektro¬ denträgerkörper 2' does not only a rear Flächenaus- recess 8 'has, but further includes a front-side surface recess 14 has'. Preferably, this is produced in the second etching step, simultaneously with the generation of the residue is side surface recess 8 '. By vorder¬ side and back surface recess 8 ', 14' are in the embodiment of Fig. 13 are each inclined to the major surfaces extending inclined surfaces 15 ', 16' formed.

As in the embodiments according to FIGS. 14 through 16 is indicated, can in deviation to the embodiments shown in FIGS. 12 and 13 depending on the use of isotropic or anisotropic etching processes either a parallel or a ge tends to the vertical direction opposing the course of the walls 17 'of the flow openings 7a' to 7e are obtained '. For the skilled person it is obvious that the 'to the front face 5' konver¬ gent in FIGS. 14 and 15 of the back 6 during the walls 17 'and diverging course of the walls 17' is achieved in that the Durchströ - mung openings 7a ', 7b' of the front 5 'and from the rear side 6' are prepared starting etched. Correspondingly, wall course diverging both starting from the front 5 'and from the rear side 6', achieved by suitable choice of the etching method, wherein the sectional shape of the throughflow shown in Fig. 16 openings 7 'results.

is As shown in FIGS. 17 to 20 verdeut¬ in top view, practically any of the Durchströ¬ can be mung opening 7 'is selected, shaped as rectangular, for example, circular, diamond-shaped, elliptical, qua¬ flow openings dratische, star-shaped or honeycomb-shaped Durch¬ 7a 'to 7e'.

As shown in Fig. 21, one or both of the electrodes may be 10 ', 11' configured in the embodiment shown therein that it bridges in the form of Elektroden¬ 18 'extend through the through flow openings 7'. In this way, an increased charge carrier injection is achieved in the fluid. To improve the mechanical strength of the electrode bridges 18 may be reinforced 9 '' by underlying support body 19 'of the insulation layer.

As shown in the plan view illustration of the twelfth and dreizehn¬ th embodiment shown in FIGS. 23 and 24, the electrode bridges 18 'of the flow opening an arbitrary orientation with respect 7' may have.

In a modification of the exemplary embodiment just described can play the electrodes 10 'in place in the form of electrodes bridges in the form of electrode tips 20', 21 extend into 'in the flow-through opening 7'.

As shown in the fifteenth embodiment shown in FIG. 26, it is not necessary that the cover Elek¬ trodes 10 'the entire surface of the electrode support body 2'. For localization of the charge carrier injection, it is beneficial to connect to a terminal section 24 'only the tips 20', 21 'with each other and. As further illustrated in the fifteenth embodiment, the electrode tips 20 ', 21' through corresponding, likewise 'are mechanically reinforced in the through-flow openings 7' hineinreichen¬ de support body 22 ', 23 can.

The Strömungsgeschwindigkeitsmeßvorrichtung or pump can not only by micromechanical methods, such as the etching technique, wer¬ produced in a reproducible manner to, but be likewise implemented by means of the so-called LIGA-tech technology and be integrated into micro-mechanical components. In this case, the Elektrodenträger¬ can body 2 made of plastic (such as PMMA) or glass. When using the LIGA process, the structures may be er¬ testifies having a large aspect ratio, which refers to the width divided by the length of the flow openings Durch¬. Here, a relatively thick resist layer is first exposed by means of synchrotron radiation and after the development of the same electrically aufge¬ with metal fills and continued on the structure of the resist layer, so that a continuous mold insert is formed. From die¬ sem plastic Negative be produced in mass production by means of molding technique by injection molding and Reaktionsgießtechniken that can be used by subsequent metallization as Elektro¬ denträgerkörper 2 'of the Mikrompumpe. The advantage of this LIGA process is that one can her¬ provide on the one hand vertical openings with arbitrary shapes and on the other hand, as already mentioned, the aspect ratio, which divided the depth of the flow opening concerned by its width, wer¬ made very large the can ,

In the initially described embodiment, that is, a material capable leit¬ the electrode support body of silicon. Only by using such a conductive electrode support body 2 ', it is necessary, either by depositing on this or by chemical reaction of the electrode support body 2' to generate an insulation layer itself. One can for the isolation of the front 5 'and back sides 6' and the through-flow openings 7 'use either a single insulating material or using different materials for these areas. Thus, it is possible, for example, flow apertures within the Durch¬ 7 between the two electrodes ', 11' produces 10 'so that a more homogeneous field within the flow-through openings 7 for the linear potential drop apply a low conductive material'. The homogenization of the electric field within the flow-through opening 7 'can also be achieved in that the metallization of the front and rear 5', 6 is separated 'by small isolated areas of the regions of the flow opening 7'.

For the skilled person it is obvious that for enhancing the pumping action more uniform electrode support body 2 can be arranged 'in the direction of flow staggered one behind the other. In order to increase the flow cross-section, it is also possible to connect a plurality of uniform or similar electrode support body 2 'in fluid parallel.

Ultimately, the microminiaturized electrostatic pump according to the invention can also be used for generating a static pressure, so that the term used in the present application, "pump" includes also applications in which a fluid without any fluid flow is to be only applied with a pressure. Further, it should be understood also any device to accelerate or decelerate a flow of fluid in the sense of the present application, the term "pump".

Claims

- 23 -Patentansprüche
A microminiaturized electrostatic pump with wenig¬ least two in a to be pumped substantially nicht¬ conductive fluid or in a to be pumped, which is arranged essentially non-conductive gas, vonein¬ other beabstan- essentially in the pump flow direction Deten electrodes (10 ', 11' ) which can be acted upon with a potential for injecting or accelerating a trodes between the Elek¬ (10 ', 11') flowing through the liquid or gas ion current and (with at least one electrode support body 2 '),
characterized,
that the electrode carrier body (2 ') on its two major surfaces (5', 6 ') each of the two electrodes (10' comprises, 11 '),
that the electrode carrier body (2 ') relative to at least one of the two electrodes (10', 11 ') is isolated and
that the electrode carrier body (2 ') at least one substantially vertically to its main faces (5' having, 6 ') extending through the flow opening (7').
2. An apparatus for determining the flow velocity of a gas or a liquid, comprising
two mutually substantially spaced apart in the gas or in the liquid in the flow direction Elek¬ trodes (10 ', 11') which are so be¬ whippable with a voltage, one of the electrodes (10 ', 11') in the gas or injected into the liquid ions whose charge at least partially on the other electrode (10 ', 11') is transferred, whereby a sense current is produced,
a generator (22; 26) for generating a varying voltage signal to zeit¬ Lich, which can be applied to the electrodes (10 ', 11'),
a current detector (23; 27, 28) for detecting a change of the voltage caused by the change of the measurement current, and
an evaluation device (20, 21; 24, 25, 29) for measuring the time duration between the change in voltage and the change of the measuring current and for determining the flow velocity of the gas and the fluid auf¬ basis of the measured time duration,
characterized,
that both electrodes (10 ', 11') on the main surfaces (5 ', 6') of a common electrode support body (2 ') are ordered an¬,
that the electrode carrier body (2 ') relative to at least one of the two electrodes (10', 11 ') is isolated and
that the electrode carrier body (2 ') at least one substantially vertically to its main faces (5' having, 6 ') extending Durchströmungsδffnung (7').
3. The apparatus or pump according to claim 1 or 2, characterized gekennzeichne,
that the electrode carrier body (2 ') consists of a conductor material Halb¬,
that the electrode carrier body (2 ') from a Oxid¬ layer (9') of the semiconductor material is enclosed, and
that the electrodes (10 ', 11') by two-sided sierungen be metallized on the oxide layer (9 ') are formed.
4. The apparatus or pump of any one of claims 1 to 3, characterized in that
that the electrode carrier body (2 ') consists of a dielectric.
5. The apparatus or pump of any one of claims 1 to 3, characterized in that
that the electrode carrier body (2 ') through a front and / or rear surface recess (8', 14 ') in the region of at least one throughflow opening (7') comprises a relative to its peripheral region (4 ') diminished extension vertically (to its major surfaces 5', 6 ').
6. The apparatus or pump according to claim 5, characterized in that
that the front and / or rear Flächenaus¬ recess (8 ', 14') by inclined to the major surfaces (5 ', 6') running oblique surfaces (15 ', 16') are enclosed.
7. The apparatus or pump of any one of claims 1 to 6, characterized in that
that the through-flow openings (7 ') are rectangular or circular or elliptical or square or diamond-shaped or bienenwabenformig or star-shaped.
8. The apparatus or pump of any one of claims 1 to 7, characterized in that
that the electrodes (10 ', 11') support body via the Elektroden¬ (2 ') extends out to the Durchströmungsöff¬ voltages (7') extend.
9. Device according to one of claims 2 to 8,
marked by
a clock generator (20),
one of the clock generator (20) clocked counter (21) whose count start by the generator (22) can be fixed and the end of counting by the current detector (23) is festleg¬ bar.
10. Device according to one of claims 2 to 9,
marked by
a flow measurement device (10) having two Elektroden¬ sets (10 ', 11') of the generator (26) are acted upon by two voltage signals;
two peak value detectors (27, 28), the measuring device of the Durchflu߬ (10) are arranged downstream and whose output signals Aus¬ an exclusive-OR gate (29) are supplied, which starts a clocked counter (25) and stops. 11. A pump according to claim 1, characterized in that
that the electrode carrier body (2 ') is made of a conductive material or a conductive semiconductor material, and
that this (2 ') is contacted via a .Check connection and is supplied with a potential, whereby the field profiles are changed in the flow opening.
AMENDED CLAIMS
[(11/25/92) received at the International Bureau on 25 November 1992; original claims 1-3 amended; all other claims unchanged (5 pages)]
A microminiaturized electrostatic pump with wenig¬ least two in a to be pumped substantially nicht¬ conductive fluid or in a to be pumped, which is arranged essentially non-conductive gas, vonein¬ other beabstan- substantially in Pumpströmungsrichtuήg Deten electrodes (10 ', 11' ), with a potential for injecting or accelerating a trodes between the Elek¬ (10 ', 11') flowing through the liquid or gas ion current can be acted upon, and (with at least one electrode support body 2 '), the at least one substantially vertically has its major surfaces extending flow opening,
characterized,
that the electrodes (10 ', 11') by metallizations on the two main faces of the electrode support body (2 ') are formed so that the thickness of the Elektrodenträ¬ gerkörpers (2' determines the mutual spacing of the electrodes (10 ', 11')) , and
that the electrode carrier body (2 ') is either made of an insulating material or with respect to at least one of the two electrodes (10', 11 ') is insulated by a layer tion Isola¬.
2. An apparatus for determining the flow velocity of a gas or a liquid, comprising two mutually spaced apart substantially in the gas or in the liquid in the flow direction Elek¬ trodes (10 ', 11') which are so be¬ whippable to a voltage that one of the electrodes thereby transmitting a measurement current is generated (10 ', 11') is injected into the gas or in the liquid ions whose charge at least partially on the other electrode (10 '11'),
a generator (22; 26) for generating a varying voltage signal to zeit¬ Lich, which can be applied to the electrodes (10 ', 11'),
a current detector (23; 27, 28) for detecting a change of the voltage caused by the change of the measurement current, and
an evaluation device (20, 21; 24, 25, 29) for measuring the time duration between the change in voltage and the change of the measuring current and for determining the flow velocity of the gas and the fluid auf¬ basis of the measured time duration,
characterized,
that the electrodes (10 ', 11') 'are formed so that the thickness of the electrode support body (2 through metallizations on the two main surfaces of a common Elektroden¬ carrier body (2)'), the mutual spacing of the electrodes (10 ', 11') determines
that the electrode carrier body (2 ') is either made of an insulating material or with respect to at least one of the two electrodes (10', 11 ') by a Isola¬ tion layer is isolated, and
that the electrode carrier body (2 ') at least one substantially vertically to its main surfaces (5', 6 ') ou
has extending flow opening (7 ').
3. The apparatus or pump according to claim 1 or 2, characterized in that
that the electrode carrier body (2 ') consists of a conductor material Halb¬, and
that the electrode carrier body (2 ') from a Oxid¬ layer (9') of the semiconductor material is enclosed.
The apparatus or pump of any one of claims 1 to 3, characterized in that
that the electrode carrier body (2 ') consists of a dielectric.
5. The apparatus or pump of any one of claims 1 to 3, characterized in that
that the electrode carrier body (2 ') by a vorder¬ side and / or back surface recess (8', 14 ') in the region of at least one throughflow opening (7') comprises a relative to its peripheral region (4 ') ver¬ diminished extension vertical to its major surfaces (5 ', 6') on eist.
6. The apparatus or pump according to claim 5, characterized in that
that the front and / or rear Flächenaus¬ recess (8 ', 14') by inclined to the major surfaces (5 ', 6') running oblique surfaces (15 ', 16') are enclosed.
7. The apparatus or pump of any one of claims 1 to 6, characterized in that
that the through-flow openings (7 ') are rectangular, circular, or ellipsenformig or square or diamond-shaped or bienenwabenformig or star-shaped.
8. The apparatus or pump of any one of claims 1 to 7, characterized in that
that the electrodes (10 ', 11') support body via the Elektroden¬ (2 ') extends out to the Durchströmungsöff¬ voltages (7') extend.
9. Device according to one of claims 2 to 8,
marked by
a clock generator (20),
one of the clock generator (20) clocked counter (21) whose count start by the generator (22) can be fixed and the end of counting by the current detector (23) is festleg¬ bar.
10. Device according to one of claims 2 to 9,
marked by
a flow measurement device (10) having two Elektroden¬ sets (10 ', 11') of the generator (26) are acted upon by two voltage signals; two peak value detectors (27, 28), the measuring device of the Durchflu߬ (10) are arranged downstream and whose output signals Aus¬ an exclusive-OR gate (29) are supplied, which starts a clocked counter (25) and stops.
11. A pump according to claim 1, characterized in that
that the electrode carrier body (2 ') is made of a conductive material or a conductive semiconductor material, and
that this (2 ') is contacted via a terminal and is applied with a potential, so that the field gradients will change in the flow opening.
PCT/DE1992/000409 1991-05-31 1992-05-15 Microminiaturized electrostatic pump and device for determining the flow rate of a gas or liquid WO1992021883A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
DEP4117914.5 1991-05-31
DE19914117914 DE4117914C2 (en) 1991-05-31 1991-05-31
DEP4117912.9 1991-05-31
DE19914117912 DE4117912C2 (en) 1991-05-31 1991-05-31 Apparatus for determining the flow velocity of a gas or a liquid

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Publication Number Publication Date
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0603844A1 (en) * 1992-12-23 1994-06-29 INSTITUT FÜR MIKROTECHNIK MAINZ GmbH Microminiaturized electrostatic pump and method of production thereof
US6033544A (en) * 1996-10-11 2000-03-07 Sarnoff Corporation Liquid distribution system
US6117396A (en) * 1998-02-18 2000-09-12 Orchid Biocomputer, Inc. Device for delivering defined volumes
US6881039B2 (en) * 2002-09-23 2005-04-19 Cooligy, Inc. Micro-fabricated electrokinetic pump

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2752328A1 (en) * 1976-11-30 1978-06-01 Nissan Motor Apparatus for measuring fluid flow rates
EP0050998A1 (en) * 1980-10-07 1982-05-05 Regie Nationale Des Usines Renault Differential-type traversing-time ions pick-up head
DE3925749C1 (en) * 1989-08-03 1990-10-31 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung Ev, 8000 Muenchen, De

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2752328A1 (en) * 1976-11-30 1978-06-01 Nissan Motor Apparatus for measuring fluid flow rates
EP0050998A1 (en) * 1980-10-07 1982-05-05 Regie Nationale Des Usines Renault Differential-type traversing-time ions pick-up head
DE3925749C1 (en) * 1989-08-03 1990-10-31 Fraunhofer-Gesellschaft Zur Foerderung Der Angewandten Forschung Ev, 8000 Muenchen, De

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0603844A1 (en) * 1992-12-23 1994-06-29 INSTITUT FÜR MIKROTECHNIK MAINZ GmbH Microminiaturized electrostatic pump and method of production thereof
US6033544A (en) * 1996-10-11 2000-03-07 Sarnoff Corporation Liquid distribution system
US6117396A (en) * 1998-02-18 2000-09-12 Orchid Biocomputer, Inc. Device for delivering defined volumes
US6881039B2 (en) * 2002-09-23 2005-04-19 Cooligy, Inc. Micro-fabricated electrokinetic pump

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