WO1992021883A1 - Pompe electrostatique microminiaturisee et dispositif de mesure de la vitesse d'ecoulement de gaz ou de liquides - Google Patents

Pompe electrostatique microminiaturisee et dispositif de mesure de la vitesse d'ecoulement de gaz ou de liquides 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
Authority
WO
WIPO (PCT)
Prior art keywords
electrodes
flow
carrier body
electrode carrier
electrode
Prior art date
Application number
PCT/DE1992/000409
Other languages
German (de)
English (en)
Inventor
Klaus Hofmann
Axel Richter
Hermann Sandmaier
Andreas Plettner
Original Assignee
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE4117914A external-priority patent/DE4117914A1/de
Priority claimed from DE4117912A external-priority patent/DE4117912C2/de
Application filed by Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. filed Critical Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Publication of WO1992021883A1 publication Critical patent/WO1992021883A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04F—PUMPING OF FLUID BY DIRECT CONTACT OF ANOTHER FLUID OR BY USING INERTIA OF FLUID TO BE PUMPED; SIPHONS
    • F04F99/00—Subject matter not provided for in other groups of this subclass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B5/00—Electrostatic spraying apparatus; Spraying apparatus with means for charging the spray electrically; Apparatus for spraying liquids or other fluent materials by other electric means
    • B05B5/16—Arrangements for supplying liquids or other fluent material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/704—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow using marked regions or existing inhomogeneities within the fluid stream, e.g. statistically occurring variations in a fluid parameter
    • G01F1/708—Measuring the time taken to traverse a fixed distance
    • G01F1/7088—Measuring the time taken to traverse a fixed distance using electrically charged particles as tracers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/18—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
    • H02N11/00—Generators or motors not provided for elsewhere; Alleged perpetua mobilia obtained by electric or magnetic means
    • H02N11/006—Motors

Definitions

  • the present invention relates to a microminiaturized electrostatic pump with at least two electrodes which are arranged in a substantially non-conductive liquid to be pumped or in a substantially non-conductive gas to be pumped and which are spaced from one another essentially in the direction of the pump flow. which can be acted upon with a potential for injecting or accelerating an ion current flowing between the electrodes through the liquid or the gas and with at least one electrode carrier body, according to the preamble of patent claim 1.
  • a microminiaturized electrostatic pump is already from the German patent DE 39 25 749 Cl of the applicant known.
  • This known pump comprises two semiconductor bodies arranged one above the other in the pump flow direction, which are designed, for example, in the form of a lattice or web for integrally forming electrodes as a component of the semiconductor body.
  • the two electrode support bodies In order to ensure that the electrostatic pump functions properly, the two electrode support bodies must be joined to one another with high accuracy, so that the respective electrode web structures or electrode grid structures are opposite one another with a small distance in the pump flow direction.
  • tolerances arise in the mutual alignment of the semiconductor bodies, which are comparatively large compared to the tolerances of the electrode structures which are formed by means of lithographic processes within the electrode carrier bodies are. Due to the requirement of mutual alignment of the two electrode carrier bodies, further miniaturization of the pump is limited, so that this known pump, despite its outstanding properties, cannot yet be completely satisfied with regard to the effort required in its manufacture.
  • the electrode spacing is determined by the vertical extent of the electrode carrier body, so that the accuracy of the mutual arrangement of the two electrodes corresponds to the high accuracy that can be achieved when using lithographic methods.
  • the running time of an ion front injected into a liquid or into a gas moves from the injecting electrode to a receiving electrode the velocity of the gas or liquid moving between the electrodes, so that the flow rate of the gas or of the liquid can be determined by detecting the time shift of the change in the measuring current after the voltage applied to the electrodes has changed.
  • FIG. 1 shows a first embodiment of a measuring device
  • FIG. 3 shows a block diagram for the determination of the flow speed on the basis of the signals emitted by the measuring device shown in FIG. 1;
  • FIG. 4 shows another block diagram for determining the flow velocity on the basis of the signals emitted by the measuring device shown in FIG. 2;
  • 21, 22 are perspective sectional views of a tenth and eleventh embodiment of an essential component of the flow rate measuring device or pump according to the invention.
  • FIG. 2 shows a further embodiment of a flow measuring device, which is designated in its entirety with reference number 10.
  • This also comprises a tube 12, a plurality of injector electrodes 13 arranged perpendicularly to the flow direction and conductively connected to one another, a first plurality of collector electrodes 14a spaced apart from the flow direction to the injector electrodes 13, and a second plurality of flow electrodes to the injector electrodes 13 arranged collector electrodes 14b. Both sets of collector electrodes each extend perpendicular to the direction of flow and are conductively connected to one another.
  • FIG. 4 is a block diagram of a circuit for determining the flow rate for a flow measuring device 10 as shown in FIG. 2.
  • This circuit comprises a clock generator 24 and a counter 25 connected downstream of the clock generator 24.
  • the circuit comprises a pulse generator 26 for generating the voltage pulse U (t), which is fed to the flow measuring device 10 (see FIG. 2).
  • the two measuring voltages U, (t) and U 2 (t) from the flow measuring device 10, which drop across the resistors R1 and R2, are fed to a first and a second peak value detector 27, 28, the output signals of which via an exclusive-OR gate 29 to a start -Stop signal for the counter 25 can be linked.
  • the counter 25 of this circuit detects the time difference between the detection of the peak values by the peak value detectors 27, 28. This cycle can run continuously repeatedly after resetting the counter and the detector.
  • the time behavior of the measuring current which is dependent on the flow velocity, is derived below for the structure of the flow measuring device 1 shown in FIG. 1.
  • the liquid flows perpendicular to the electrodes 3, 4.
  • the liquid is pressed through the grid formed by the electrodes 3, 4 by means of an external pump (not shown).
  • the liquid has a flow that is constant over time and place, that is to say that the pressure generated by the external pump (not shown) is much greater than the pressure generated by the injecting electrodes 3 itself, and that there is no turbulence within the Liquid appear. Based on this assumption, the following equations are obtained:
  • t describes the time, x the location between the two grids, j c the line current, ⁇ the ion mobility, q the charge, E the electric field strength, v the flow velocity of the fluid and e 0 or e r the absolute or relative dielectric constant.
  • the second equation describes the strength of the injected charge at the injecting electrode q 0 . This value depends both on the nature of the electrode (eg metallization, geometry, surface roughness) and on the liquid used.
  • v 7 1 corresponds to a speed of 1 cm / s.
  • a grid area of 1 mm x 1 mm this corresponds to a flow of 0.01 cm 3 / s or 0.6 ml / min.
  • the flow velocity and thus also the volume flow of a fluid can be determined using the above equation.
  • the voltage jump leads to the injection of ions into the fluid.
  • the vertical axis denotes the current density j 'at the injecting electrode 3 as a function of time, with different space charge densities at the collector electrode 4 as parameters as the space charge densities between 0.1 and 20.0.
  • the voltage jump leads to an acceleration of the ions in the electric field in the direction of the collector electrode 4.
  • the measured current density reaches a maximum at time t 0 , that of the arrival the first charge carrier is caused on the collector electrode 4.
  • the progress of the ion front can be clearly seen here.
  • Fig. 7 shows the associated course of the electric field strength E 'as a function of the normalized distance' also at the times mentioned above.
  • FIG. 8 shows a measurement of the current curve as a function of time in a practically implemented exemplary embodiment according to FIG. 1, the fluid used in this measurement setup being deionized water.
  • the dependency between the drift time and the flow rate can now be determined for a given flow measuring device 1, so that each measured drift time can be assigned a corresponding flow rate or flow rate using a table.
  • the flow velocity in both flow directions can be determined by means of a single measurement setup, so that from the determination of the drift time t 0 not only the absolute flow velocity but also its direction can be derived.
  • changes in the electrochemical properties of the fluid during the measurement lead to slight measurement inaccuracies in this measurement setup, since the drift time t 0 is dependent on the electrochemical properties of the fluid.
  • two oppositely arranged pairs of injector electrodes and collector electrodes can be used, as well as a single measuring cell which only consists of three electrodes, which comprises a central injector 13 and two outer collectors 14a, 14b.
  • a first embodiment of a flow velocity measuring device or pump essentially comprises an electrode carrier body 2 'which is enclosed by a housing 3.
  • the housing 3 ' can be, for example, a housing cast from a plastic, which firmly encloses a peripheral region 4' of the electrode carrier body 2 '.
  • the type of configuration of the housing 3 'as a cast housing or as a housing screwed from two halves with an intermediate seal lies at the discretion of the person skilled in the art and requires no further explanation for the purposes of the present invention.
  • An 8-molar KOH solution is preferably used as the etching solution in order to suppress the formation of competing levels.
  • an etching stop layer is applied to the front 5 'and the rear etching stop layer is opened.
  • the silicon body 2 ' is removed to produce a rear surface recess 8'. etches until the flow openings 7 'extend completely through the silicon body 2'.
  • the entire electrode support body 2 ' is thermally oxidized to produce an insulation layer 9' in the area of the throughflow openings 7a 'to 7e' and on the front 5 'and the rear 6' of the electrode support body 2 '.
  • a metallization is then applied to both the front 5 'and the rear 6', which forms electrodes 10 ', 11'.
  • These electrodes 10 ', 11' are provided with connections 12 ', 13' which extend to the outside of the housing 3 '.
  • the number of flow openings 7a 'to 7e' can be between one and a few thousand, depending on the application, the size of a single flow opening varying between 0.1 micrometer and 1 millimeter, the width and length of a flow opening 7a 'to 7e' can be chosen independently.
  • a direct voltage or alternating voltage is applied to the connections 12, 13, which is selected to be high enough to inject charge carriers in the area of the passage openings 7a to 7e comes, the charge carriers passing through the flow openings 7a to 7e in the position shown in FIG. 1 in the vertical direction and thereby entraining the medium to be pumped.
  • the electrode carrier body 2 consists of a conductive material or semiconductor material, this can contacted via a connection and applied with a potential. This allows the field profiles in the flow areas to be changed.
  • the second embodiment shown in FIG. 13 of the flow velocity measuring device or pump 1 'according to the invention differs from the embodiment according to FIG. 12 essentially in that in this the electrode carrier body 2' not only has a rear surface recess 8 ', but also has a front surface recess 14 '. In the second etching step, this is preferably produced simultaneously with the production of the rear surface recess 8 '.
  • inclined surfaces 15 ′, 16 ′ are formed in each case by the front and rear surface recesses 8 ′, 14 ′.
  • any shape of the flow opening 7 ' can be selected, such as, for example, rectangular, circular, diamond-shaped, elliptical, square, star-shaped or honeycomb-shaped flow openings 7a 'to 7e'.
  • one or both of the electrodes 10 ', 11' can be designed such that they extend in the form of electrode bridges 18 'over the flow openings 7'. This results in an increased charge carrier injection into the fluid.
  • the electrode bridges 18 ' can be reinforced by underlying support bodies 19' of the insulation layer 9 '.
  • the electrode bridges 18 ' can have any orientation with respect to the flow opening 7'.
  • the electrodes 10 ' it is in no way necessary for the electrodes 10 'to cover the entire surface of the electrode carrier body 2'. To localize the charge carrier injection it is beneficial to connect only the tips 20 ', 21' to one another and to a connection area 24 '. As is also shown in the fifteenth embodiment, the electrode tips 20 ', 21' can be mechanically reinforced by corresponding support bodies 22 ', 23' which also extend into the flow openings 7 '.
  • the flow velocity measuring device or pump can not only be produced in a reproducible manner using methods of micromechanics, such as, for example, etching technology, but can also be implemented using so-called LIGA technology and integrated into micromechanical components.
  • the electrode carrier body 2 can be made of plastic (such as PMMA) or glass.
  • the structures with a large aspect ratio which denotes the length of the throughflow openings divided by their width, can be produced.
  • a comparatively thick resist layer is first exposed by means of synchrotron radiation and, after its development, is galvanically filled with metal and continued over the structure of the resist layer, so that a coherent use of the mold is produced.
  • Plastic negatives are produced from this in mass production by means of the impression technique by injection molding and reaction molding techniques, which after subsequent metallization can be used as an electrode carrier body 2 'of the micropump.
  • the advantage of this LIGA process is that, on the one hand, vertical openings with any shape can be produced and, on the other hand, as already mentioned, the aspect ratio, which relates to the depth of the throughflow opening divided by its width, can be chosen to be very large .
  • the electrode carrier body consists of silicon, ie a conductive material. It is only necessary to use electrode carrier bodies 2 'of this type, either by depositing thereon or by chemical reaction of the electrode carrier body 2 'itself to produce an insulation layer. You can either use a uniform insulating material for the insulation of the front side 5 'or the rear side 6' and the flow openings 7 'or different materials can be used for these areas. For example, it is possible to apply a low-conductivity material within the flow openings 7 ', so that a more homogeneous field is generated within the flow openings 7' between the two electrodes 10 ', 11' because of the linear potential drop. The homogenization of the electric field within the throughflow opening 7 'can also be achieved in that the metallization on the front and back 5', 6 'is separated from the regions of the throughflow opening 7' by narrow insulated zones.
  • a plurality of uniform electrode carrier bodies 2 ' can be arranged in a staggered manner in the flow direction in order to increase the pumping action.
  • a plurality of uniform or similar electrode carrier bodies 2 'in parallel in terms of flow it is also possible to connect a plurality of uniform or similar electrode carrier bodies 2 'in parallel in terms of flow.
  • the microminiaturized electrostatic pump according to the invention can also be used to generate a static pressure, so that the term “pump” used in the present application also encompasses applications in which a fluid without fluid flow is only to be pressurized. Furthermore, the term “pump” in the sense of the present application is also to be understood to mean any device for accelerating or braking a fluid flow.

Abstract

Une pompe électrostatique microminiaturisée comprend au moins deux électrodes mutuellement espacées (10', 11') et un corps (2') porte-électrodes. De même, un dispositif de détermination de la vitesse d'écoulement d'un gaz ou d'un liquide comprend au moins deux électrodes mutuellement espacées (10', 11') et un corps (2') porte-électrodes. Afin de simplifier la production d'un tel dispositif ou d'une telle pompe, les deux électrodes (10', 11') sont agencées sur les surfaces principales d'un corps (2') porte-électrodes commun isolé par rapport à au moins une des deux électrodes (10', 11') et pourvu d'une ouverture d'écoulement pratiquement verticale par rapport à ses surfaces principales.
PCT/DE1992/000409 1991-05-31 1992-05-15 Pompe electrostatique microminiaturisee et dispositif de mesure de la vitesse d'ecoulement de gaz ou de liquides WO1992021883A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DEP4117912.9 1991-05-31
DE4117914A DE4117914A1 (de) 1991-05-31 1991-05-31 Mikrominiaturisierte elektrostatische pumpe
DEP4117914.5 1991-05-31
DE4117912A DE4117912C2 (de) 1991-05-31 1991-05-31 Vorrichtung zum Bestimmen der Strömungsgeschwindigkeit eines Gases oder einer Flüssigkeit

Publications (1)

Publication Number Publication Date
WO1992021883A1 true WO1992021883A1 (fr) 1992-12-10

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Application Number Title Priority Date Filing Date
PCT/DE1992/000409 WO1992021883A1 (fr) 1991-05-31 1992-05-15 Pompe electrostatique microminiaturisee et dispositif de mesure de la vitesse d'ecoulement de gaz ou de liquides

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Country Link
WO (1) WO1992021883A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0603844A1 (fr) * 1992-12-23 1994-06-29 INSTITUT FÜR MIKROTECHNIK MAINZ GmbH Pompe électrostatique microminiaturisée et méthode pour la réalisation de celle-ci
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 (de) * 1976-11-30 1978-06-01 Nissan Motor Vorrichtung zum messen von fluiddurchflussmengen
EP0050998A1 (fr) * 1980-10-07 1982-05-05 Regie Nationale Des Usines Renault Capteur ionique à temps de transit de type différentiel
DE3925749C1 (fr) * 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 (de) * 1976-11-30 1978-06-01 Nissan Motor Vorrichtung zum messen von fluiddurchflussmengen
EP0050998A1 (fr) * 1980-10-07 1982-05-05 Regie Nationale Des Usines Renault Capteur ionique à temps de transit de type différentiel
DE3925749C1 (fr) * 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 (fr) * 1992-12-23 1994-06-29 INSTITUT FÜR MIKROTECHNIK MAINZ GmbH Pompe électrostatique microminiaturisée et méthode pour la réalisation de celle-ci
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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