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EP1064538A1 - Diagrammes d'impulsions electroniques asymetriques, equilibres, con us pour faire fonctionner des pompes comportant des electrodes - Google Patents

Diagrammes d'impulsions electroniques asymetriques, equilibres, con us pour faire fonctionner des pompes comportant des electrodes

Info

Publication number
EP1064538A1
EP1064538A1 EP98910505A EP98910505A EP1064538A1 EP 1064538 A1 EP1064538 A1 EP 1064538A1 EP 98910505 A EP98910505 A EP 98910505A EP 98910505 A EP98910505 A EP 98910505A EP 1064538 A1 EP1064538 A1 EP 1064538A1
Authority
EP
European Patent Office
Prior art keywords
polarity
voltage
electrodes
pump
ratio
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP98910505A
Other languages
German (de)
English (en)
Inventor
Sterling E. Mcbride
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sarnoff Corp
Original Assignee
Sarnoff Corp
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
Application filed by Sarnoff Corp filed Critical Sarnoff Corp
Publication of EP1064538A1 publication Critical patent/EP1064538A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/447—Systems using electrophoresis
    • G01N27/44756—Apparatus specially adapted therefor
    • G01N27/44791—Microapparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00851—Additional features
    • B01J2219/00853—Employing electrode arrangements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00781—Aspects relating to microreactors
    • B01J2219/00891—Feeding or evacuation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L2400/00—Moving or stopping fluids
    • B01L2400/04—Moving fluids with specific forces or mechanical means
    • B01L2400/0403—Moving fluids with specific forces or mechanical means specific forces
    • B01L2400/0415—Moving fluids with specific forces or mechanical means specific forces electrical forces, e.g. electrokinetic

Definitions

  • the present invention is directed to a method of operating an electrode-based pump, which can be an electrohydrodynamic pump, or operating an electrophoresis apparatus, using an asymmetric electrical pulse pattern.
  • Electrode-based pumps have no moving parts. Such systems, can be used for example, to relay liquids in very small devices, to conduct multiple parallel, but non- equivalent, small-scale syntheses, or to conduct multiple small-scale analytical reactions.
  • the present applicant observed that some of the liquids selected to be pumped were susceptible to having unwanted electrochemical reactions occur at the pumping electrodes. Where this electrochemistry leads to substantial bubble formation at the pumping electrodes, pumping efficiency is diminished, or even stops. Accordingly, the invention provides methods for reducing or eliminating such bubbling at electrodes. In addition to improving electrode-based pumping, the invention is applicable in electrophoresis applications, where bubbling can also interfere with process efficiency.
  • the process of the invention utilizes periodic reversals in the polarity applied to electrodes while maintaining a sufficient electronic impetus for pumping or electrophoresis in a desired direction. It is believed that, in the context of slab gel electrophoresis, particularly "submarine" gels that are electrophoresed when submerged under a layer of buffer, so-called - 2 -
  • pulsed field methods have been used that apply modulations in field orientation to orient very large molecules during the electrophoresis process. See Schwartz and Cantor, Cell 37: 67-75, 1984. These are modulations are not believed to be reversals in voltage polarity applied to two reference electrodes.
  • the present invention provides a method of and apparatus for operating an electrode-based pump by inducing transfer of particles responsive to a preselected asymmetric motive force.
  • the preselected motive force can be electrical, magnetic, mechanical, chemical, or a selected combination thereof.
  • the invention provides a method of operating an electrode-based pump for the purpose of pumping a liquid, the method comprising periodically reversing the voltage polarity applied to the electrodes of the pump, while maintaining a net flow of liquid in a desired direction.
  • the voltage polarity reversals are applied by repeating a defined pattern with a defined frequency, wherein the defined pattern is made up of a voltage amplitude profile of a first polarity, which first polarity causes pumping in the desired direction, and a voltage amplitude profile of a second polarity opposite that of the first.
  • the frequency is at least about 10 Hz. More preferably, the frequency is from about 10 Hz to about 100 MHz.
  • the frequency can be between about 100 Hz to about 10 kHz,; and yet still more preferably from about 100 Hz to about 1 kHz.
  • the maximum applied voltage of the first polarity is greater than the maximum applied voltage of the second polarity.
  • the maximum voltage of the first polarity is at least about 10 N; more preferably, at least about 100 N; and yet more preferably, at least about 500 N.
  • the maximum voltage of the second polarity is no more than about 50% of the maximum voltage of the first polarity; more preferably no more than about 40%; yet more preferably no more than about 30%.
  • the particular voltage applied will be related, for example, to factors such as the geometry of the pumping electrodes, the geometry of the associated fluid channel, and the susceptibility of the pumped liquid to dielectric breakdown.
  • These preferred voltages reflect, among other things, a preference for voltages that are readily driven in high-density arrangements with off-the-shelf electronics.
  • a first ratio of a voltage-integrated area Ai associated with a first polarity to a voltage-integrated area A 2 associated with the other polarity or (b) a second ratio of a charge qi carried by the current associated with a first polarity to a charge q 2 carried by the current associated with the other polarity is between about 1 : Vi and about Vz : 1.
  • the voltage-integrated areas are the voltage profiles integrated over the relevant time period.
  • the operation of the pump satisfies one of the ratio parameters when the pump is operated over a period of time of at least about 10 seconds without generating a sufficient rate of bubbling to stop liquid flow.
  • the first ratio or the second ratio is between about 1 : 0.8 and about 0.8 : 1, yet more preferably the first or second ratio is between about 1 : 0.9 and about 0.9 : 1 , still more preferably is between about 1 : 0.95 and about 0.95 : 1 , yet still more preferably is between about 1 : 0.98 and about 0.98 : 1.
  • the first ratio or the second ratio is between about 1 : 0.8 and about 0.8 : 1
  • the first or second ratio is between about 1 : 0.9 and about 0.9 : 1
  • the apparatus is operated pursuant to a control mechanism set such that one of these ratios is equal to one.
  • the limitations of the control mechanism will imply some operational variance from this control target, but in this latter embodiment the effective ratio should remain within about 20% of unity.
  • the electrode-based pump comprises three or more electrodes, and wherein the voltage monitored at two of the electrodes displays the periodically reversing voltage.
  • the pump is operated to pump a liquid with a time-averaged pressure of P, and with essentially no gas bubbles observable, for example, by eye or by the aid of a microscope, and wherein, if the electrodes were driven by a constant DC voltage effective to pump the liquid with pressure P, the liquid would generate observable gas bubbles.
  • the pump is operated to pump a liquid with essentially no observable gas bubbles, wherein the liquid has a conductivity of at least about 10 "4 S/m.
  • the pump can be operated without bubble generation with a liquid having a conductivity of at least about 10 "3 S/m, or at least about 10 "2 S/m.
  • the invention provides an apparatus for pumping liquid with an electrode-based pump having a liquid flow pathway, the apparatus comprising: a channel of capillary dimensions forming at least part of the flow pathway; a pump comprising at least two electrodes inserted into the flow pathway; a controller for controlling the voltages applied to the electrodes such that the pumps operate under a sequentially repeated pattern of polarity cycles, and such that over the period of the repeated pattern either (a) a first ratio of a voltage- integrated area Ai associated with a first polarity to a voltage-integrated area A 2 associated with the other polarity or (b) a second ratio of a charge qi carried by the current associated with a first polarity to a charge q 2 carried by the current associated with the other polarity is between about 1 : Vi and about Vi : 1.
  • the controller operates pursuant to a programmable microprocessor, and wherein the microprocessor is programmed to sequentially and repetitively operate the pattern of polarity cycles.
  • the microprocessor is programmed to sequentially and repetitively operate the pattern of polarity cycles.
  • the electrodes are inserted into the channel or (ii) the flow pathway comprises a reservoir for feeding liquid to the channel, one or more electrodes of the pump are inserted into the reservoir, and one or more of the electrodes are inserted into the channel.
  • the invention provides a method of operating a capillary electrophoresis apparatus having at least one electrode at each end of an electrophoresis pathway and operating with an electrophoresis liquid, the method comprising: periodically reversing the voltage polarity applied to the electrodes while maintaining a net electrophoretic migration of one or more solutes in a desired direction.
  • the method further comprises selecting a pattern of polarity reversals and an associated voltage amplitude profile reduce or eliminate the nucleation of gas at the electrodes.
  • the voltage polarity reversals are applied by repeating a defined pattern with a defined frequency, wherein the defined pattern comprises a voltage amplitude profile of a first polarity, which first polarity causes electrophoresis of the one or more solutes in the desired direction, and a voltage amplitude profile of a second polarity opposite that of the first.
  • the frequency is at least about 10 Hz.
  • the frequency is from about 10 Hz to about 100 MHz, more preferably from about 100 Hz to about 10 kHz, yet more preferably from about 100 Hz to about 1 kHz.
  • the maximum voltage applied of the first polarity is greater than the maximum applied voltage of the second polarity.
  • the maximum voltage of the second polarity is no more than about 50% of the maximum voltage of the first polarity, more preferably no more than about 40%, yet more preferably no more than about 30%.
  • a first ratio of a voltage-integrated area Ai associated with a first polarity to a voltage-integrated area A 2 associated with the other polarity or (b) a second ratio of a charge qi carried by the current associated with a first polarity to a charge q carried by the current associated with the other polarity is between about 1 : Vi and about Vi : 1.
  • the operation of the electrodes satisfies one of the ratio parameters when the pump is operated over a period of time of at least about 10 seconds without generating a sufficient rate of bubbling to retard electrophoretic migration.
  • the first ratio or the second ratio is between about 1 : 0.8 and about 0.8 : 1, more preferably the first or second ratio is between about 1 : 0.9 and about 0.9 : 1, yet more preferably is between about 1 : 0.95 and about 0.95 : 1 , yet still more preferably is between about 1 : 0.98 and about 0.98 : 1.
  • the apparatus is operated pursuant to a control mechanism set such that one of these ratios is equal to one.
  • the limitations of the control mechanism will imply some operational - 6 -
  • the effective ratio should remain within about 20% of unity (1).
  • the electrodes are operated to move a the solute with a time averaged mobility of M and with no gas nucleations observable by eye, and wherein the liquid that would, if the electrodes were driven by a constant DC voltage effective to move the one solute with a mobility of M, generate gas nucleations that would be observable by eye.
  • the electrodes are operated to move one solute with no gas nucleations observable by eye, wherein the liquid has a conductivity of at least about 10 ⁇ 2 S/m.
  • the invention provides a method of operating an electrophoresis apparatus having at least one electrode at each end of an electrophoresis pathway and operating with an electrophoresis liquid, the method comprising periodically reversing the voltage polarity applied to the electrodes while maintaining a net electrophoretic migration of one or more solutes in a desired direction, wherein a pattern of polarity reversals and an associated voltage amplitude profile are selected to reduce or eliminate the nucleation of gas at the electrodes.
  • the voltage polarity reversals are applied by repeating a defined pattern with a defined frequency of at least about 10 Hz.
  • the invention provides an electrophoresis apparatus having at least one electrode at each end of an electrophoresis pathway comprising: two electrodes situated such that the distance between them encompasses the electrophoresis pathway, in which pathway electrophoretic separation is anticipated to occur; a controller for controlling the voltages applied to the electrodes such that the electrodes operate under a sequentially repeated pattern of polarity cycles, and such that over the period of the repeated pattern either (a) a first ratio of a voltage-integrated area Ai associated with a first polarity to a voltage-integrated area A 2 associated with the other polarity or (b) a second ratio of a charge qi carried by the current associated with a first polarity to a charge q 2 carried by the current associated with the other polarity is between about 1 : Vi and about Vi : 1.
  • the controller operates pursuant to a programmable microprocessor, and wherein the microprocessor is programmed to sequentially and repetitively operate the pattern of polarity cycles.
  • the apparatus incorporates for the electrophoresis pathway additional electrodes at one or both ends. - 7 -
  • Figure 1 displays a square wave voltage driving pattern.
  • Figure 2 shows a schematic of electrical drivers that can be used with the invention.
  • Definitions The following terms shall have, for the purposes of this application, the meaning set forth below. In particular, for the purpose of interpreting the claims, the term definitions shall control over any assertion of a contrary meaning based on other text found herein:
  • Channel dimensions are dimensions that favor capillary flow of a liquid.
  • channels of capillary dimensions are no wider than about 1.5 mm.
  • channels are no wider than about 500 ⁇ m, yet more preferably no wider than about 250 ⁇ m, still more preferably no wider than about 150 ⁇ m.
  • a polarity cycle is the whole of (a) a continuous period operating with one of the polarities, and (b) an immediately following continuous period operating with the opposite polarity.
  • the present invention had its origin in the observation that in electrode-based pumping processes, particularly in electrohydrodynamic pumping processes, a number of liquids exhibited excessive bubbling. These are typically liquids with relatively high conductivity such as 0J M butylamine in dimethylformamide (conductivity 0.007 S/m), but include other liquids of lower conductivity. It has now been observed that net fluid movement in the desired direction could be maintained while minimizing electrolysis, other electrochemical processes, or like bubble-generating events at the electrodes by periodically reversing the polarity applied to the electrodes.
  • the invention uses a repeat pattern of a square wave of voltage of a first polarity which drives pumping in the desired direction followed by a square wave of lower amplitude and longer duration, as illustrated in Figure 1.
  • the initial observation was that optimization of bubble minimization appeared to occur when the product of the amplitude of the first square wave times its duration was approximately equal to the corresponding product for the second square wave.
  • this principle one compares the areas defined by integrating voltage - 8 -
  • this area measurement is generally the most readily measured parameter and, at least over the voltage ranges most useful for operating the electrode-based devices of the invention, is highly correlated with the net charge parameter. This correlation is due to the current, over the relevant voltage range, being substantially linearly related to the voltage.
  • Electrohydrodynamic pumping EHD
  • EO electroosmosis
  • EHD pumping has been described by Bart et al., “Microfabricated Electrohydrodynamic Pumps,” Sensors and Actuators, A21-A23: 193-197, 1990 and Richter et al., “A Micromachined Electrohydrodynamic Pump,” Sensors and Actuators, A29: 159-168, 1991.
  • EO pumps have been described by Dasgupta et al., - 9 -
  • EO pumping is believed to take advantage of the principle that the surfaces of many solids, including quartz, glass and the like, become charged, negatively or positively, in the presence of ionic materials, such as salts, acids or bases.
  • the charged surfaces will attract oppositely charged counter ions in solutions of suitable conductivity.
  • the application of a voltage to such a solution results in a migration of the counter ions to the oppositely charged electrode, and moves the bulk of the fluid as well.
  • the volume flow rate is proportional to the current, and the volume flow generated in the fluid is also proportional to the applied voltage.
  • the electrodes that cause flow can be spaced further apart than in EHD pumping, since the electrodes are only involved in applying force, and not, as appears to apply in EHD, in creating charges on which the force will act.
  • EO pumping is generally perceived as a method appropriate for pumping conductive solutions.
  • the present invention is believed to be applicable to all forms of electrode-based pumping, which pumping is also referred to herein as "electrokinetic" pumping.
  • the invention is most preferably applied to electrode-based pumping where the field strength directly acts on liquid components to create pressure, as in EHD and EO.
  • the invention is also applicable to other electrode-based methods, such as traveling wave methods, that are believed to operate by creating heat convection forces.
  • the pumps applied in the present invention can be made of simple wire electrodes.
  • this reference is to conditions which, if repeated in a comparable device where the electrodes can be viewed, shows an appropriate level of gas nucleations.
  • the invention can be applied in several contexts beyond simple two-electrode pumps, and that these contexts are intended to be within the scope of the claims.
  • the invention can be applied where several electrodes are incorporated into a channel to allow flexibility in selecting electrodes most appropriate for pumping a particular fluid.
  • complex electrode-based pumping protocols such as traveling wave protocols, the invention is being utilized if it is used with respect to the voltage patterns applied to two electrodes in the array of electrodes.
  • the values % ⁇ , ⁇ 2 and ⁇ 3 designate, respectively, the start time of a polarity cycle, the end time for the first continuous period operating under a first polarity, and the end time for the following continuous period operating under the second polarity, as illustrated in Figure 1.
  • This condition indicates that the area of the positive part Aj of the voltage waveform is approximately equal to the area of the negative part A 2 of the voltage waveform.
  • This condition can be expressed as
  • i(t) is the cuirent as a function of time.
  • the pressure P is given by
  • Electrophoresis The same types of operational guidelines as apply for electrode-based pumping apply for electrophoresis. The major difference is that when seeking to electrophorese a certain class of molecules voltage parameters will be selected based on the voltages typically used, in contexts outside of the present invention, with comparable electrophoresis devices, and these voltages may not be similar to the voltages used with like fluids in the electrode-based pumping context.
  • Drivers
  • Driving circuits are set forth in U.S. Application No. 08/469,238, filed June 6, 1995 (DSRC 1 1717) and U.S. Application No. 08/556,423, filed November 9, 1995 (DSRC 11717A), which applications are incorporated herein in their entirety.
  • a preferred circuit is set forth in Figure 2.
  • Box 1 houses control electronics, which can be interfaced with a computer.
  • Solid state switch A (for example a transistor or an operational amplifier) is used to generate a positive cycle (or if the driving polarity is negative, a negative cycle).
  • Solid state switch B is used to generate a negative cycle (or if the driving polarity is negative, a positive cycle).
  • the voltage applied to the pump 2 is a combination of the two waveforms.
  • the waveforms generated by the two illustrated switches A and B, and the resulting waveform, are represented in the figure, with an indication of a reference voltage.
  • one or more of the driving electrodes can be placed in the reservoir so as to provide the relatively greater spacing between the driving electrodes that favors the EO mechanism of electrode-based pumping.
  • the electrode-based pumps that selectively drive liquid through the channels each will include a separate set of one or more electrodes inserted into each channel connected to the reservoir, but a plurality of such pumps will share electrodes located in the connected reservoir.
  • a planar pump in a channel 240 ⁇ m wide and 80 ⁇ m deep was used.
  • the pump was two electrodes inserted into the channel with a 250 ⁇ m spacing between them.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Molecular Biology (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Dispersion Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

L'invention se rapporte à un procédé permettant de faire fonctionner une pompe comportant des électrodes et conçue pour pomper un liquide. Ledit procédé consiste à inverser périodiquement la polarité de la tension appliquée aux électrodes de la pompe tout en maintenant un flux net de liquide dans une direction souhaitée (Fig. 1). L'invention se rapporte également à un appareil conçu pour pomper du liquide à l'aide d'une pompe à électrodes et comportant un canal de dimensions capillaires, une pompe comportant au moins deux électrodes insérées à l'intérieur du canal ; un organe de commande conçu pour commander les tensions appliquées aux électrodes de sorte que les pompes fonctionnent sous l'effet d'un diagramme à répétition de cycles de polarité, et de sorte qu'au cours de la période du diagramme répété on obtient soit (a) qu'un premier rapport d'une aire (A1) intégrée en tension, associée à une première polarité, à une aire (A2) intégrée en tension, associée à l'autre polarité, soit (b) qu'un second rapport d'une charge (q1) transportée par le courant associé à une première polarité à une charge (q2) transportée par le courant associé à l'autre polarité, soit compris entre 1:1/2 environ et 1/2:1 environ. L'invention se rapporte également à des appareils et procédés de mise en oeuvre d'une électrophorèse.
EP98910505A 1998-03-20 1998-03-20 Diagrammes d'impulsions electroniques asymetriques, equilibres, con us pour faire fonctionner des pompes comportant des electrodes Withdrawn EP1064538A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1998/005485 WO1999049306A1 (fr) 1998-03-20 1998-03-20 Diagrammes d'impulsions electroniques asymetriques, equilibres, conçus pour faire fonctionner des pompes comportant des electrodes

Publications (1)

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EP1064538A1 true EP1064538A1 (fr) 2001-01-03

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EP (1) EP1064538A1 (fr)
JP (1) JP2002511149A (fr)
AU (1) AU6473298A (fr)
CA (1) CA2284268A1 (fr)
WO (1) WO1999049306A1 (fr)

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GB0903134D0 (en) * 2009-02-24 2009-04-08 Osmotex Ag Charged particle motion inducing apparatus
DE102009045446A1 (de) * 2009-10-07 2011-04-14 Robert Bosch Gmbh Lambdasonden-Betriebsverfahren und Vorrichtung zur Durchführung des Verfahrens
JP2012189498A (ja) * 2011-03-11 2012-10-04 Sharp Corp 電界発生装置および電界発生方法

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US4101220A (en) * 1977-03-31 1978-07-18 General Electric Company Laser Doppler spectroscopy with smoothened spectra line shapes
US5015351A (en) * 1989-04-04 1991-05-14 Miller John B Method for electrochemical treatment of porous building materials, particularly for drying and re-alkalization
US5292416A (en) * 1992-11-13 1994-03-08 Indiana University Foundation Pulsed-field separation of polysaccharides in capillaries

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See references of WO9949306A1 *

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WO1999049306A1 (fr) 1999-09-30
CA2284268A1 (fr) 1999-09-30
AU6473298A (en) 1999-10-18
JP2002511149A (ja) 2002-04-09

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