WO2006130779A2 - Procede et appareil de nettoyage et de conditionnement de surfaces d'objets par plasma - Google Patents

Procede et appareil de nettoyage et de conditionnement de surfaces d'objets par plasma

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Publication number
WO2006130779A2
WO2006130779A2 PCT/US2006/021308 US2006021308W WO2006130779A2 WO 2006130779 A2 WO2006130779 A2 WO 2006130779A2 US 2006021308 W US2006021308 W US 2006021308W WO 2006130779 A2 WO2006130779 A2 WO 2006130779A2
Authority
WO
WIPO (PCT)
Prior art keywords
dielectric barrier
planar dielectric
barrier plate
proximate
probes
Prior art date
Application number
PCT/US2006/021308
Other languages
English (en)
Other versions
WO2006130779A3 (fr
Inventor
Peter Kurunczi
Original Assignee
Cerionx, Inc.
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 US11/143,083 external-priority patent/US20060272674A1/en
Priority claimed from US11/142,988 external-priority patent/US8092643B2/en
Priority claimed from US11/143,552 external-priority patent/US20060272675A1/en
Application filed by Cerionx, Inc. filed Critical Cerionx, Inc.
Publication of WO2006130779A2 publication Critical patent/WO2006130779A2/fr
Publication of WO2006130779A3 publication Critical patent/WO2006130779A3/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass

Definitions

  • Patent No. 7,017,594 which is a divisional of U.S. Patent Application Serial No. 10/858,272, filed June 1 , 2004, which application claims the benefit of U.S. Provisional Patent Application Serial No. 60/478,418, filed on June 16, 2003, all prior applications of which are incorporated herein by reference in their entirety.
  • Embodiments of the present invention generally relate to a method and apparatus for cleaning and surface conditioning fluid handling devices and in particular to a method and apparatus for cleaning and surface conditioning portions of fluid handling devices using plasma.
  • liquid is aspirated from a fluid holding device into a fluid handling device.
  • the fluid handling device may include, but is not limited to, a probe, cannula, disposable pipette, pin tool or other similar component or plurality of such components (hereinafter collectively referred to as "probes").
  • the fluid handling device and its probes may move, manually, automatically or robotically, dispensing the aspirated liquid into another fluid holding device for testing purposes.
  • the probes are reused from one test to the next. As a result, at least the tips of the probes must be cleaned between each test. Conventionally, the probes undergo a wet "tip wash” process. That is, they are cleaned in between uses with a liquid solvent, such as Dimethyl Sulfoxide (DMSO) or simply water.
  • DMSO Dimethyl Sulfoxide
  • an apparatus for cleaning objects using plasma comprising at least one planar dielectric barrier plate having a first surface and a second surface, and at least one electrode proximate the second surface of the at least one planar dielectric plate, wherein the planar dielectric barrier plate is positioned to receive at least one object substantially orthogonally proximate the first surface.
  • an apparatus for cleaning objects using plasma comprising at least one planar dielectric barrier plate having a first surface and a second surface, at least one electrode proximate the second surface of the at least one planar dielectric barrier plate, and a ground plane proximate the first surface of the at least one planar dielectric barrier plate, wherein the ground plane includes apertures sized and arranged for receiving at least one object to be cleaned, and wherein the planar dielectric barrier plate is positioned to receive at least one object substantially orthogonally proximate the first surface.
  • a method for cleaning objects using plasma comprising introducing at least one planar dielectric barrier plate having a first surface and a second surface, introducing at least one electrode proximate the second surface of the at least one planar dielectric barrier plate, wherein the at least one planar dielectric barrier plate is positioned to receive the objects substantially orthogonally proximate the first surface, introducing the objects proximate the at least one planar dielectric barrier plate, wherein the objects are made substantially of a conductive material, and generating a dielectric barrier discharge to form plasma around the at least one planar dielectric barrier plate for cleaning at least a portion of the objects.
  • a method of cleaning objects using plasma comprising the steps of introducing at least one planar dielectric barrier plate having a first surface and a second surface, introducing at least one electrode proximate the second surface of the at least one planar dielectric barrier plate, introducing a ground plane proximate the first surface of the at least one planar dielectric barrier plate, the ground plane having apertures sized and arranged for receiving at least one object to be cleaned, wherein the at least one planar dielectric barrier plate and ground plane are positioned to receive the objects substantially orthogonally proximate the first surface, introducing the objects proximate the at least one planar dielectric barrier plate, and generating a dielectric barrier discharge to form plasma around the at least one planar dielectric barrier plate and the ground plane for cleaning at least a port/on of the objects.
  • Figure 1A is a top, partial perspective view of a plurality of conductive probes being introduced to a plurality of elongated dielectric barrier members with coupled inner electrodes in accordance with an embodiment of the present invention
  • Figure 1B is a top, partial perspective view of one conductive probe being introduced to one dielectric barrier member with a coupled inner electrode in accordance with an embodiment of the present invention
  • Figure 2 is a front, expanded view of the device and the conductive probes of Figure 1A showing the components electrically coupled;
  • Figure 3A is a cross sectional schematic view of the device and a conductive probe of Figure 1A showing the dimensions and spacing among components;
  • Figure 3B is a cross sectional schematic view of the device of Figure 1A showing a conductive probe proximate the top of a dielectric barrier member;
  • Figure 4 is a top plan view of a matrix or array of the device of Figure 1A showing the plurality of elongated dielectric barrier members arranged in a microtiter plate format;
  • Figure 5 represents a graph of the relative concentrations of different chemical and particle species of plasma in time after the initiation of a single microdischarge that forms atmospheric pressure plasma in air;
  • Figure 6 is a top, partial perspective view of a plurality of probes being introduced to a plurality of elongated dielectric barrier members with coupled inner electrodes in accordance with another embodiment of the present invention;
  • Figure 7 is a top, partial perspective view of a plurality of probes being introduced to a plurality of elongated dielectric barrier members with coupled inner electrodes in accordance with yet another embodiment of the present invention
  • Figure 8 is a partial, cross sectional view of the embodiment shown in Figure 7;
  • Figure 9 is a top plan view of a matrix or array of the devices of Figures 6 or 7 showing the plurality of elongated dielectric barrier members arranged in a microtiter plate format;
  • Figure 10 is a perspective view depicting a plurality of conductive probes introduced substantially orthogonally to a first surface of a planar dielectric barrier plate and an electrode proximate a second surface of the planar dielectric barrier plate opposite the plurality of probes, in accordance with an embodiment of the present invention
  • Figure 11A is a perspective view depicting a plurality of non-conductive probes introduced substantially orthogonally to a first surface of a planar dielectric barrier plate having an electrode proximate a second surface of the planar dielectric barrier plate opposite the plurality of probes, and a ground plane proximate the planar dielectric barrier plate, in accordance with an embodiment of the present invention
  • Figure 11B is a side view of a probe introduced to the dielectric barrier plate and ground plane of Figure 11 A; in accordance with an embodiment of the present invention.
  • Figure 12 is a side view depicting a plurality of conductive probes introduced substantially orthogonally to a first surface of a planar dielectric barrier plate having an electrode proximate to a second surface of the planar dielectric barrier plate opposite the plurality of probes, and a vacuum system, in accordance with an embodiment of the present invention
  • Figure 13A is a top plan view of the device of Figure 10 showing the planar dielectric barrier plate arranged in a microtiter plate format, in accordance with an embodiment of the present invention.
  • Figure 13B is a top plan view of the device of Figures 11 A and 11B showing the planar dielectric barrier plate and proximate ground plane arranged in a microtiter plate format, in accordance with an embodiment of the present invention.
  • plasma is used to describe a quasi-neutral gas of charged and neutral species characterized by a collective behavior governed by coulomb interactions. Plasma is typically obtained when sufficient energy, higher than the ionization energy of the neutral species, is added to the gas causing ionization and the production of ions and electrons.
  • the energy can be in the form of an externally applied electromagnetic field, electrostatic field, or heat.
  • the plasma becomes an electrically conducting medium in which there are roughly equal numbers of positively and negatively charged particles, produced when the atoms/molecules in a gas become ionized.
  • a plasma discharge is produced when an electric field of sufficient intensity is applied to a volume of gas. Free electrons are then subsequently accelerated to sufficient energies to produce electron-ion pairs through inelastic collisions. As the density of electrons increase, further inelastic electron atom/molecule collisions will result in the production of further charge carriers and a variety of other species.
  • the species may include excited and metastable states of atoms and molecules, photons, free radicals, molecular fragments, and monomers.
  • metastable describes a type of atom/molecule excited to an upper electronic quantum level in which quantum mechanical selection rules forbid a spontaneous transition to a lower level.
  • quantum mechanical selection rules forbid a spontaneous transition to a lower level.
  • such species have long, excited lifetimes.
  • excited states with quantum mechanically allowed transitions typically have lifetimes on the order of 10 ⁇ 9 to 10 "8 seconds before relaxing and emitting a photon
  • metastable states can exist for about 10 ⁇ 6 to 10 1 seconds.
  • the long metastable lifetimes allow for a higher probability of the excited species to transfer their energies directly through a collision with another compound and result in ionization and/or dissociative processes.
  • the plasma species are chemically active and/or can physically modify the surface of materials and may therefore serve to form new chemical compounds and/or modify existing compounds.
  • the plasma species can modify existing compounds through ionization, dissociation, oxidation, reduction, attachment, and recombination.
  • a non-thermal, or non-equilibrium, plasma is one in which the temperature of the plasma electrons is higher than the temperature of the ionic and neutral species.
  • energetic and reactive particles i.e., species
  • species such as ultraviolet photons, excited and/or metastable atoms and molecules, atomic and molecular ions, and free radicals.
  • N 2 , N, O 2 , O there are excited, metastable, and ionic species of N 2 , N, O 2 , O, free radicals such as OH, HO 2 , NO, O, and O 3 , and ultraviolet photons ranging in wavelengths from 200 to 400 nanometers resulting from N 2 , NO, and OH emissions.
  • free radicals such as OH, HO 2 , NO, O, and O 3
  • ultraviolet photons ranging in wavelengths from 200 to 400 nanometers resulting from N 2 , NO, and OH emissions.
  • embodiments of the present invention harness and use these "other" particles to clean and surface condition portions of liquid handling devices, such as probes, and the like.
  • the device 100 includes a plurality of elongated dielectric barrier members 102 arranged in a matrix or array, which lie in a plane.
  • the members 102 are substantially regularly spaced apart from each other forming a gap 103 between adjacent members 102.
  • Each dielectric barrier member 102 includes an inner electrode 104 extending within, and substantially along the length of, respective elongated dielectric barrier members 102.
  • a plurality of conductive probes 106 are shown extending into open spaces or gaps 103 between the plurality of dielectric barrier members 102. In one embodiment, the probes 106 are part of a fluid handling device.
  • the probes 106 are attached to and extend from a fluid handling device (not shown), which may be part of a microtiter plate test bed set up.
  • the probes 106 may be any form of a conductive element that would benefit from plasma cleaning.
  • the elongated dielectric barrier members 102 are made of any type of material capable of providing a surface for a dielectric barrier discharge of atmospheric pressure plasma (described herein).
  • Dielectric barrier material useful in this embodiment of the present invention includes, but is not limited to, ceramic, glass, plastic, polymer epoxy, or a composite of one or more such materials, such as fiberglass or a ceramic filled resin (available from Cotronics Corp., Wetheril) Park, Australia).
  • a ceramic dielectric barrier is alumina or aluminum nitride.
  • a ceramic dielectric barrier is a machinable glass ceramic (available from Corning Incorporated, Corning, NY).
  • a glass dielectric barrier is a borosilicate glass (also available from Corning Incorporated, Coming, NY).
  • a glass dielectric barrier is quartz (available from GE Quartz, Inc., Willoughby, OH).
  • a plastic dielectric barrier is polymethyl methacrylate (PLEXIGLASS and LUCITE, available from Dupont, Inc., Wilmington, DE).
  • a plastic dielectric barrier is polycarbonate (also available from Dupont, Inc., Wilmington, DE).
  • a plastic dielectric barrier is a fluoropolymer (available from Dupont, Inc., Wilmington, DE).
  • a plastic dielectric barrier is a polyimide film (KAPTON, available from Dupont, Inc., Wilmington, DE).
  • Dielectric barrier materials useful in the present invention typically have dielectric constants ranging between 2 and 30. For example, in one embodiment that uses a polyimide film plastic such as KAPTON, at 50% relative humidity, with a dielectric strength of 7700 Volts/mil, the film would have a dielectric constant of about 3.5.
  • the inner electrode 104 may comprise any conductive material, including metals, alloys and conductive compounds.
  • a metal may be used.
  • Metals useful in this embodiment of the present invention include, but are not limited to, copper, silver, aluminum, and combinations thereof.
  • an alloy of metals may be used as the inner electrode 104.
  • Alloys useful in this embodiment of the present invention include, but are not limited to, stainless steel, brass, and bronze.
  • a conductive compound may be used. Conductive compounds useful in the present invention include, but are not limited to, indium-tin-oxide.
  • the inner electrodes 104 of the present invention may be formed using any method known in the art.
  • the inner electrodes 104 may be formed using a foil. In another embodiment of the present invention, the inner electrodes 104 may be formed using a wire. In yet another embodiment of the present invention, the inner electrodes 104 may be formed using a solid block of conductive material. In another embodiment of the present invention, the inner electrodes 104 may be deposited as an integral layer directly onto the inner core of the dielectric barrier members 102. In one such embodiment, an inner electrode 104 may be formed using a conductive paint, which is applied to the inner core of the elongated dielectric barrier members 102. Alternative electrode designs are contemplated by embodiments of the present invention.
  • the conductive probes 106 are part of the fluid handling device and are introduced in the gap 103, i.e., proximate the elongated dielectric barrier members 102 of the plasma cleaning device 100.
  • probe throughout this application is meant to include, but not be limited to, probes, cannulas, pin tools, pipettes and spray heads or any portion of a fluid handling device that is capable of carrying fluid. These portions can be generally hollow to carry the fluid but may be solid and include a surface area capable of retaining fluid.
  • the probe is conductive and is made of conductive material similar to that material described above in connection with the inner electrode 104. In other embodiments, as described below, the probe is non-conductive.
  • Figure 1 B depicts a non-thermal atmospheric pressure plasma cleaning device 100' in accordance with another embodiment of the present invention.
  • this embodiment only one elongated dielectric barrier member 102' and one inner electrode 104' are shown.
  • only one conductive probe 106' is introduced proximate the dielectric 102'.
  • multiple elongated dielectric barrier members 102' with respective inner electrodes 104', where conductive probes 106' are introduced proximate the elongated dielectric barrier members 102' are contemplated by embodiments of the present invention.
  • Each conductive probe 106 may be introduced proximate one ( Figure 1B) or more ( Figure 1A) elongated dielectric barrier members 102. When each conductive probe 106 is proximate one elongated dielectric barrier member 102, the conductive probe 106 may be introduced proximate the top of the elongated dielectric barrier member 102 as best shown in Figure 1B. When each conductive probe 106 is introduced proximate two elongated dielectric barrier members 102, the conductive probe 106 may be introduced proximate or between the two elongated dielectric barrier members 102, as best shown in Figure 1A.
  • FIG. 200 a portion of an atmospheric pressure plasma device is designated 200.
  • This section 200 includes a plurality of inner electrodes 204 of each respective elongated dielectric barrier member 202 electrically connected to an AC voltage source 208.
  • the conductive probes 206 are electrically grounded with respect to the AC voltage source 208.
  • the AC voltage source 208 in this embodiment includes an AC source 207, a power amplifier 209 and a transformer 211 to supply voltage to the inner electrodes 204.
  • a dielectric barrier discharge (DBD) also known as a "silent discharge” technique is used to create microdischarges of atmospheric pressure plasma.
  • a sinusoidal voltage from an AC source 207 is applied to at least one inner electrode 204, within an insulating dielectric barrier member 202.
  • Dielectric barrier discharge techniques have been described in "Dielectric-barrier Discharges: Their History, Discharge Physics, and Industrial Applications", Plasma Chemistry and Plasma Processing, Vol. 23, No. 1 , March 2003, and “Filamentary, Patterned, and Diffuse Barrier Discharges", IEEE Transactions on Plasma Science, Vol. 30, No. 4, August 2002, both authored by U.
  • a dielectric barrier is placed in between the electrode 204 and the conductive probe 206 to control the discharge, i.e., choke the production of atmospheric pressure plasma. That is, before the discharge can become an arc, the dielectric barrier 202 chokes the production of the discharge. Because this embodiment is operated using an AC voltage source, the discharge oscillates in a sinusoidal cycle. The microdischarges occur near the peak of each sinusoid.
  • One advantage to this embodiment is that controlled non-equilibrium plasmas can be generated at atmospheric pressure using a relatively simple and efficient technique.
  • the AC voltage source 208 applies a sinusoidal voltage to the inner electrodes 204. Then, the plurality of conductive probes 206 are introduced into the gap 203 between adjacent elongated dielectric barriers 202. A dielectric barrier discharge (DBD) is produced. This DBD forms atmospheric pressure plasma, represented by arrows 210.
  • atmospheric pressure plasma is obtained when, during one phase of the applied AC voltage, charges accumulate between the dielectric surface and the opposing electrode until the electric field is sufficiently high enough to initiate an electrical discharge through the gas gap (also known as "gas breakdown").
  • an electric field from the redistributed charge densities may oppose the applied electric field and the discharge is terminated.
  • the applied voltage-discharge termination process may be repeated at a higher voltage portion of the same phase of the applied AC voltage or during the next phase of the applied AC voltage.
  • a point discharge generally develops within a high electric field region near the tip of the conductive probe 206.
  • the AC voltage source 208 includes an AC power amplifier 209 and a high voltage transformer 211.
  • the frequency ranges from about 10,000 Hertz to about 20,000 Hertz, sinusoidal.
  • the power amplifier has an output voltage of from about 0 Volts (rms) to about 22.5 Volts (rms) with an output power of about 500 watts.
  • the high voltage transformer ranges from about 0 V (rms) to 7,000 Volts (rms) (which is about 10,000 volts (peak)).
  • the applied voltages can range from about 500 to about 10,000 Volts (peak), with frequencies ranging from line frequencies of about 50 Hertz up to about 20 Megahertz.
  • the frequency of a power source may range from 50 Hertz up to about 20 Megahertz.
  • the voltage and frequency may range from about 5,000 to about 15,000 Volts (peak) and about 50 Hertz to about 50,000 Hertz, respectively.
  • the gas used in the plasma device 200 embodiment of the present invention can be ambient air, pure oxygen, any one of the rare gases, or a combination of each such as a mixture of air or oxygen with argon and/or helium.
  • the gas may include an additive, such as hydrogen peroxide, or organic compounds such as methanol, ethanol, ethylene or isopropynol to enhance specific atmospheric pressure plasma cleaning properties.
  • FIG. 3A depicts one example of the geometry and relationship among components of one embodiment of the present invention.
  • the elongated dielectric barrier member 302 may comprise, for example, an elongated hollow tube with a hollow inner electrode 304 extended substantially the length of the elongated dielectric barrier member 302.
  • the elongated dielectric barrier member 302 may be other than a tube such as a solid with a solid inner electrode 304.
  • the elongated dielectric barrier 302 may be formed of different shapes as well.
  • the shape of the elongated dielectric barrier may be tubular, circular, square, rectangular, oval, polygonal, triangular, trapezoidal, rhombus and irregular. If tubular, each dielectric barrier tube is about 2 mm in diameter and about 75 to about 120 mm long.
  • the elongated dielectric barrier members 302 are placed adjacent one another, defining a plane. They are spaced at regular intervals and form a gap 303, designated as spacing A. Alternatively, the members 302 can be staggered in a non-planar arrangement with respect to one another.
  • the spacing A is sized to allow at least a portion of each of the plurality of probes to be introduced proximate or between the elongated dielectric barrier members.
  • the gap 303 or spacing A can approach zero, provided there is a sufficient gap to allow gas such as air to flow through the elongated dielectric barrier members 302. Spacing A or gap 303 can range from about 0 mm to about 10 mm.
  • the spacing A or gap 303 may also range from about 2 mm to about 9.5 mm. In one embodiment, the spacing A is about 9 mm. In another embodiment, the spacing A is about 4.5 mm. In yet another embodiment, the spacing A is about 2.25 mm.
  • the probe 306 diameter is relatively smaller than the diameter of the plurality of elongated dielectric barrier members.
  • the probes 306' can be introduced generally proximate the top of each elongated dielectric barrier member 302'.
  • Figure 3B depicts only one probe 306' and one dielectric 302' but it is to be understood the present invention contemplates a plurality of probes 306' being introduced proximate the top of respective dielectric barrier members 302'.
  • the microtiter plate format may be sized to accommodate about 96 openings for receiving a plurality of fluid handling probes.
  • the microtiter plate is sized to accommodate about 384 openings for receiving a plurality of probes as depicted in Figure 4.
  • the wells and the pitch between rows of wells of the microtiter plate are sized to accommodate about 1536 openings for receiving a plurality of probes.
  • Microtiter plates or microplates are small, usually plastic, reaction vessels.
  • the microplate 400 has a tray or cassette 410 covered with wells or dimples 412 arranged in orderly rows. These wells 412 are used to conduct separate chemical reactions during a fluid testing step.
  • the large number of wells which typically number 96, 384 (as shown in Figure 4) or 1536, depending upon the well size and pitch between rows of wells of the microplate allow for many different reactions to take place at the same time.
  • Microplates are ideal for high-throughput screening and research. They allow miniaturization of assays and are suitable for many applications including drug testing, genetic study, and combinatorial chemistry.
  • the microplate 400 has been equipped with an embodiment of the present invention. Situated in rows on the top surface of the microplate 400 and between the wells 412 are a plurality of elongated dielectric barrier members 402 similar to those described hereinabove. The inner electrodes 404 of the elongated dielectric barrier members 402 are electrically coupled to the AC voltage source through bus bars or contact planes 414 of the cassette 410.
  • the elongated dielectric barrier members 402 are each spaced apart in this particular embodiment a pitch of about 4.5 mm. In alternative embodiments, where the well count is 96, the members 402 are spaced apart a pitch of about 9 mm. In yet another embodiment, where the wells 412 numbered 1536, the pitch is 2.25 mm.
  • the wells 412 of the microplate 400 do not necessarily function as liquid holding devices. Rather, the wells 412 are used to allow receiving space for the probes when the probes are fully introduced between the elongated dielectric barrier members 402.
  • the microplate 400 is placed in, for example, a deck mounted wash station.
  • the system performs an assay test.
  • at least the probe tips of the fluid handling device would need a cleaning.
  • the fluid handling device enters the wash station.
  • a set of automated commands initiate and control the probes to be introduced to the microplate 400 proximate the elongated dielectric barrier members 402.
  • the AC voltage power source is initiated.
  • the power source remains on during an extended period.
  • the probes are introduced to the dielectric members 402 of the microplate 400.
  • dielectric barrier discharges are formed between the members 402 and the probes (see, e.g., Figure 2).
  • the reactive and energetic components or species of the plasma are repeatedly aspirated into the probes, using the fluid handling devices' aspirating and dispensing capabilities. The aspiration volume, rate and frequency are determined by the desired amount of cleaning/sterilization required.
  • Any volatized contaminants and other products from the plasma may be vented through the bottom of the microplate 400 by coupling the bottom of the tray 410 to a region of negative pressure such as a modest vacuum.
  • This vacuum may be in communication with the wells 412 and is capable of drawing down plasma and reactive byproducts through to the bottom of the device and into an exhaust manifold (not shown) of the cleaning station test set up.
  • ions, excited and metastables species (corresponding emitted photons), and free radicals are found in the atmospheric pressure plasma and remain long enough to remove substantially all of the impurities and contaminates from the previous test performed by the fluid handling device's probes. These particle species remain longer (see Figure 5) than the initial plasma formed from a DBD or microdischarge and are therefore effective in cleaning the probes in preparation for a next test as the initially formed plasma itself.
  • Figure 5 represents a graph of the relative concentrations of different particle species in time after the initiation of a single microdischarge forming atmospheric pressure plasma in air.
  • Metastables are represented by N 2 (A) and N 2 (B).
  • Free radicals are represented by O 3 , O( 3 P), N( 4 S) and NO.
  • Free radicals and metastables are represented by 0( 1 D) and N( 2 D).
  • the fast electrons created by the discharge mechanism mainly initiate the chemical reactions in the atmospheric pressure plasma.
  • the fast electrons can inelastically collide with gas molecules and ionize, dissociate, and/or excite them to higher energy levels, thereby losing part of their energy, which is replenished by the electric field.
  • the resulting ionic, free radical, and excited species can then, due to their high internal energies or reactivities, either dissociate or initiate other reactions.
  • FIG. 5 shows the evolution of the different particle species initiated by a single microdischarge in "air" (80% N 2 , plus 20% O 2 ).
  • the short current pulse of about 10 ns duration deposits energy in various excited levels of N 2 and O 2 , some of which lead to dissociation and finally to the formation of ozone and different nitrogen oxides. After about 50 ns, most charge carriers have disappeared and the chemical reactions proceed without major interference from charge carriers and additional gas heating.
  • FIG. 6 is a top, partial perspective view of a plurality of probes being introduced to a plurality of elongated dielectric barrier members with coupled inner electrodes in accordance with another embodiment of the present invention.
  • a cleaning device 600 includes a plurality of elongated dielectric barrier members 602 arranged in a matrix or array, which lie in a plane.
  • the members 602 are substantially regularly spaced apart from each other forming a gap 603 between adjacent members 602.
  • Each dielectric barrier member 602 includes an inner electrode 604 extending within, and substantially along the length of, respective elongated dielectric barrier members 602.
  • the inner electrodes 604 are electrically coupled to a voltage supply 608 similar to that described herein.
  • each dielectric barrier member 602 includes on its surface a secondary ground grid 609.
  • the ground grid 609 is in the form of a conductive spiral, coupled to the surface of each dielectric barrier member 602 and to ground.
  • plasma will extend along the surface of each elongated dielectric barrier members 602 as designated by large arrows 610.
  • conductive, electrically isolated, and non-conductive probes 606 can be treated by the plasma formed between spacing of the grid 609 because plasma formation is not necessarily dependent on the probe being conductive. Rather, plasma is formed independent of the probes on the surface of the members 602.
  • a plurality of probes 606 are shown extending into open spaces or gaps 603 between the plurality of dielectric barrier members 602.
  • the probes 606 are part of a fluid handling device.
  • the probes 606 are attached to and extend from a fluid handling device (not shown), which may be part of a microtiter plate test bed set up.
  • the probes 606 may be any form of an object that would benefit from plasma cleaning.
  • the elongated dielectric barrier members 602 are made of any type of material capable of providing a surface for a dielectric barrier discharge of atmospheric pressure plasma (described herein).
  • Dielectric barrier material useful in this embodiment of the present invention includes, but is not limited to, ceramic, glass, plastic, polymer epoxy, or a composite of one or more such materials, such as fiberglass or a ceramic filled resin (available from Cotronics Corp., Wetherill Park, Australia). The various types of materials discussed with respect to previous figures apply here as well.
  • the inner electrode 604 may comprise any conductive material, including metals, alloys and conductive compounds as described herein with respect to the other figures.
  • the inner electrodes 604 of the present invention may be formed using any method known in the art, including those mentioned herein in connection with the other figures.
  • the secondary ground grid is conductive and made of formable conductive material described herein with respect to the inner electrode.
  • the ground grid can be a separate conductive wire or conductive paint deposited on the members, and the like, as described previously.
  • the probes 606 are part of the fluid handling device and are introduced in the gap 603, i.e., proximate the elongated dielectric barrier members 602 of the plasma cleaning device 600.
  • the probe 606 can either conductive or non-conductive. If conductive, it is made of conductive material similar to that material described above in connection with the inner electrode 604. In other embodiments, as described below, the probe is non- conductive and can be made of any non-conductive material known to one of ordinary skill in the art.
  • the probes 606 can be introduced proximate the elongated dielectric barrier members 602. That is, each probe 606 may be introduced proximate one or more elongated dielectric barrier members 602. When each probe 606 is introduced proximate two elongated dielectric barrier members 602, the probe 606 may be introduced proximate or between the two elongated dielectric barrier members 602.
  • FIG. 7 is a top, partial perspective view of a plurality of probes 706 being introduced to a plurality of elongated dielectric barrier members 702 with coupled inner electrodes 704 in accordance with yet another embodiment of the present invention. Similar to Figure 6, this embodiment includes a secondary ground plane 715. In this embodiment, the ground plane 715 is in the form of a conductive mesh positioned either above or below the elongated dielectric barrier members 702. Figure 7 depicts the ground plane 715 above the members for clarity purposes but it is to be understood that a ground plane below the members 702 is also contemplated by this embodiment of the present invention. In addition ground planes above and below are contemplated and within the scope of the present invention.
  • this embodiment includes elongated dielectric barrier members, inner electrodes, probes and secondary ground grids as described hereinabove.
  • the inner electrodes are electrically coupled to a voltage source similar to that shown with respect to Figure 6 described.
  • the probes 706 can be either conductive or non- conductive as herein described.
  • Figure 8 is a partial, cross sectional view of the embodiment shown in Figure 7, depicting one example of the geometry and relationship among components of this embodiment of the present invention.
  • the elongated dielectric barrier member 802 may comprise, for example, an elongated hollow tube with a hollow inner electrode 804 extended substantially the length of the elongated dielectric barrier member 802.
  • the elongated dielectric barrier member 802 may comprise other than a tube, such as a solid with a solid inner electrode 804.
  • the elongated dielectric barrier member 802 may be formed of different shapes as well.
  • the shape of the elongated dielectric barrier member 802 may be tubular, circular, square, rectangular, oval, polygonal, triangular, trapezoidal, rhombus and irregular. If tubular, each elongated dielectric barrier member is about 2 mm in diameter and about 75 to about 120 mm long.
  • the elongated dielectric barrier members 802 are placed adjacent one another, defining a plane.
  • the secondary ground plane 815 is shown on top of the elongated dielectric barrier members 802 but would be within the scope of this embodiment if they were below the members 802.
  • the members 802 are spaced at regular intervals and form a gap 803, designated as spacing A.
  • the members 802 can be staggered in a non-planar arrangement with respect to one another.
  • the spacing A is sized to allow at least a portion of each of the plurality of probes 806 to be introduced proximate or between the elongated dielectric barrier members.
  • the gap 803 or spacing A can approach zero, provided there is a sufficient gap to allow gas such as air to flow through the elongated dielectric barrier members 802.
  • Spacing A or gap 803 can range from about 0 mm to about 10 mm.
  • the spacing A or gap 803 may also range from about 2 mm to about 9.5 mm. In one embodiment, the spacing A is about 9 mm. In another embodiment, the spacing A is about 4.5 mm. In yet another embodiment, the spacing A is about 2.25 mm.
  • spacing C is provided. Spacing C is size to provide for the production of plasma between the ground plane 815 and the elongated dielectric barrier member 802 for a given applied voltage on inner electrodes 804. Typically, spacing C ranges from about 0.0mm to about 1cm. It may also range from about 0.5mm to about 2mm.
  • Figure 9 is a top plan view of a matrix or array of a device including a ground plane similar to that shown in Figure 7, depicting the plurality of elongated dielectric barrier members arranged in a microtiter plate format 900.
  • the microtiter plate format may be sized to accommodate about 96 openings for receiving a plurality of fluid handling probes.
  • the microtiter plate is sized to accommodate about 384 openings for receiving a plurality of probes as depicted above.
  • the wells and the pitch between rows of wells of the microtiter plate are sized to accommodate about 1536 openings for receiving a plurality of probes.
  • the microplate 900 has been equipped with an embodiment of the present invention having a ground plane or grid. Situated in rows on the top surface of the microplate 900 and between the wells 912 are a plurality of elongated dielectric barrier members 902 similar to those described hereinabove. The inner electrodes 904 of the elongated dielectric barrier members 902 are electrically coupled to the AC voltage source through bus bars or contact planes 914 of the cassette 910. A meshed secondary ground plane 915 is disposed a spacing C from the elongated dielectric barrier members 902 on the top of the members. This secondary ground plane 915 is grounded with respect to the AC voltage source.
  • the elongated dielectric barrier members 902 are each spaced apart in this particular embodiment a pitch of about 4.5 mm. In alternative embodiments, where the well count is 96, the members 902 are spaced apart a pitch of about 9 mm. In yet another embodiment, where the wells 912 numbered 1536, the pitch is about 2.25 mm. The wells 912 are used to allow receiving space for the probes (not shown) when the probes are fully introduced between the elongated dielectric barrier members 902 and within the secondary ground grid 915.
  • the microplate 900 is placed in, for example, a deck mounted wash station.
  • the system performs an assay test. Then, at least the probe tips of the fluid handling device would need a cleaning. As such, the fluid handling device enters the wash station.
  • a set of automated commands initiate and control the probes to be introduced to the microplate 900 proximate the elongated dielectric barrier members 902.
  • the AC voltage power source is initiated. Alternatively, the power source remains on during an extended period.
  • the probes are introduced to the dielectric barrier members 902 of the microplate 900. At that time, dielectric barrier discharges are formed between the members 902 and the secondary ground plane 915.
  • the reactive and energetic components or species of the plasma are repeatedly aspirated into the probes, using the fluid handling devices' aspirating and dispensing capabilities. The aspiration volume, rate and frequency are determined by the desired amount of cleaning/sterilization required.
  • Any volatized contaminants and other products from the plasma may be vented through the bottom of the microplate 900 by coupling the bottom of the tray 910 to a region of negative pressure such as a modest vacuum.
  • This vacuum may be in communication with the wells 912 and is capable of drawing down plasma and reactive byproducts through to the bottom of the device and into an exhaust manifold (not shown) of the cleaning station test set up.
  • the device 1000 includes a planar dielectric barrier plate 1002 having a first surface 1008 and a second surface 1010.
  • An electrode 1004 is positioned proximate the second surface 1010 of the dielectric plate 1002.
  • the planar dielectric barrier plate 1002 material includes, but is not limited to, ceramic, glass, plastic, polymer epoxy, or a composite of one or more such materials, such as fiberglass or a ceramic filled resin.
  • the electrode 1004 may comprise any conductive material, including metals, alloys and conductive compounds.
  • a plurality of conductive probes 1006 are introduced substantially orthogonally to the first surface 1008 of the planar dielectric barrier plate 1002.
  • the probes 1006 are part of a fluid handling device (not shown).
  • the probes 1006 may be attached to, and extend from, a fluid handling device, which may be part of a microtiter plate test bed set up.
  • the probes 1006 may be any form of a conductive object or element that would benefit from plasma cleaning and surface conditioning.
  • the electrode 1004, coupled to the second surface 1010, is electrically connected to a voltage source 1012, such as an AC voltage source. Alternatively, the electrode 1004 is connected to a DC source.
  • the conductive probes 1006 are electrically grounded with respect to the AC voltage source 1012.
  • the probes 1006 are positioned such that a gap exists between a tip of each probe 1006 closest to the first surface 1008 of the planar dielectric barrier plate 1002 and the first surface 1008.
  • a dielectric barrier discharge is generated between the planar dielectric barrier plate 1002 and the probes 1006, to form plasma in the gap, thereby cleaning the tip, and likely a lower portion, of each probe 1006.
  • This embodiment is especially applicable when certain cleaning applications do not require the removal of a large amount of liquid or cleaning far up the interior and/or exterior of the tips of the probes 1006 being cleaned.
  • a non-thermal atmospheric pressure plasma cleaning device may comprise multiple planar dielectric barrier plates positioned to receive a plurality of probes substantially orthogonally.
  • FIG. 11A another embodiment of a non-thermal atmospheric pressure plasma cleaning device 1100 is disclosed.
  • the device includes a planar dielectric barrier plate 1102 with a first surface 1106 and a second surface 1108. Proximate the second surface 1108 is an electrode plate 1104 that is connected to a voltage source 1118.
  • a plurality of non-conductive probes 1110 are introduced substantially orthogonally to the first surface 1106 of the planar dielectric barrier plate 1102.
  • the probes 1110 may be made of plastic or any other type of material that does not conduct a current and as such would not cause a discharge to occur.
  • a ground plane 1112 connected to ground 1116 is proximate the first surface 1106 of the planar dielectric barrier plate 1102, opposite the electrode 1104.
  • the ground plane 1112 comprises a plate of conductive material, such as metal, for example, and includes a plurality of apertures 1114.
  • each probe 1110 is positioned proximate the first surface 1106 of the planar dielectric barrier plate and the ground plane 1112 such that a tip and lower portion of each probe 1110 enters into an aperture 1114 but does not come into contact with the first surface 1106.
  • a gap 1118 exists between the tip of each probe 1110 and the first surface 1106.
  • a dielectric barrier discharge is generated between the conductive ground plane 1112 and the planar dielectric barrier plate 1102. This discharge forms plasma in the gap 1118, which cleans the tip and lower portion of each probe 1110 placed in each aperture 1114.
  • Another embodiment includes a cleaning device with a ground grid having a plurality of apertures for receiving the non-conductive probes.
  • the device 1200 includes a vacuum system to capture byproducts produced during the plasma cleaning process, which may deposit on the planar dielectric barrier plate 1202.
  • the device 1200 comprises a planar dielectric barrier plate 1202 with a first surface 1214 and a second surface 1216. Proximate the second surface 1216 is an electrode 1204 connected to a voltage source 1218.
  • a plurality of conductive probes 1206 are introduced substantially orthogonally to the first surface 1214 such that each tip of each probe 1206 is placed near but does not contact the first surface 1214, creating a gap.
  • a dielectric barrier discharge is generated, forming plasma 1208 between the tips of each probe 1206 and the first surface 1214 of the planar dielectric barrier plate 1202. The plasma cleans the tip, and likely a lower portion, of each probe 1206.
  • a vacuum system 1210 may be used to force air 1212 onto the first surface 1214 at an end of the planar dielectric barrier plate 1202 and suction the air 1212 off the first surface 1214 at a different end of the planar dielectric barrier plate 1202, capturing any by-products that may deposit onto the planar dielectric barrier plate 1202 during the cleaning process.
  • Microtiter plates or microplates are small, usually plastic, reaction vessels.
  • the microplate has a tray or cassette covered with wells or dimples arranged in orderly rows to receive a plurality of probes or other fluid handling devices. These wells are used to conduct separate chemical reactions during a fluid testing step.
  • the large number of wells which typically number 96, 384, or 1536, depending upon the well size and pitch between rows of wells of the microplate allow for many different reactions to take place at the same time.
  • Microplates are ideal for high-throughput screening and research. They allow miniaturization of assays and are suitable for many applications including drug testing, genetic study, and combinatorial chemistry.
  • the microplate format 1300 has been equipped with an embodiment of the present invention. Situated in microplate format 1300 is a planar dielectric barrier plate 1302 and an electrode plate 1304 proximate a bottom surface of the dielectric plate 1302. Both the dielectric plate 1302 and the electrode 1304 are connected to contact planes 1306 encased in a cassette or tray 1312. The electrode 1304 is electrically coupled to an AC voltage source 1308 through the contact planes 1306, as shown at 1310.
  • the microplate format 1300 is sized to receive a plurality of conductive probes substantially orthogonally to a top surface of the planar dielectric barrier plate 1302, in accordance with a common microtiter 96-well design as discussed herein.
  • the microplate format 1300 is sized to receive 384 or 1536 conductive probes substantially orthogonally to a top surface of the dielectric plate 1302.
  • the microplate format embodiment of the present invention can be designed to receive any specific number of conductive probes arranged into a microtiter well design and that the invention is not limited to the embodiments described herein.
  • the microplate format 1300 is placed in, for example, a deck mounted wash station.
  • the system performs an assay test.
  • at least the probe tips of the fluid handling device require cleaning.
  • the fluid handling device enters the wash station.
  • a set of automated commands initiate and control the probes to be introduced to the microplate format 1300 substantially orthogonally to a top surface of the planar dielectric barrier plate 1302.
  • the AC voltage power source 1308 is initiated.
  • the power source 1308 remains on during an extended period.
  • a dielectric barrier discharge is formed between the planar dielectric barrier plate 1302 and the probes (see Figure 12).
  • the reactive and energetic components or species of the plasma are repeatedly aspirated into the probes, using the fluid handling devices' aspirating and dispensing capabilities. The aspiration volume, rate and frequency are determined by the desired amount of cleaning/sterilization required.
  • Any volatized contaminants and other products from the plasma may deposit onto the planar dielectric barrier plate 1302, and are thereby captured using a vacuum system (see Figure 12) that forces air onto the surface of the planar dielectric barrier plate 1302 at an end, and suctions the air off at a different end of the planar dielectric barrier plate 1302 into an exhaust manifold (not shown) of the cleaning station test set up.
  • a vacuum system see Figure 12
  • FIG. 13B a top plan view of the above described plasma device of Figures 11A and 11 B, configured and arranged in a standard microtiter plate format 1300, is shown and described.
  • microplate format 1320 Situated in microplate format 1320 is a planar dielectric barrier plate 1322 and an electrode plate 1324 proximate a bottom surface of the planar dielectric barrier plate 1322.
  • Both the planar dielectric barrier plate 1322 and the electrode 1324 are connected to contact planes 1326 encased in a cassette or tray 1332.
  • the electrode 1324 is electrically coupled to an AC voltage source 1328 through the contact planes 1326, as shown at 1330.
  • a ground plane 1334 comprising a plate of conductive material, such as metal, for example, with a plurality of apertures 1336 arranged to receive a plurality of non- conductive probes, which are arranged in a common microtiter well design.
  • Ground plane 1334 is grounded as shown at 1338.
  • the microplate format 1320 is sized to receive 96 non-conductive probes substantially orthogonally to a top surface of the planar dielectric barrier plate 1322, in accordance with a common microtiter well design as discussed herein.
  • the microplate format 1320 is sized to receive 384 or 1536 probes substantially orthogonally to a top surface of the dielectric plate 1322.
  • the microplate format embodiment of the present invention can be designed to receive any specific number of conductive probes arranged into a microtiter well design and that the invention is not limited to the embodiments described herein.
  • a dielectric barrier discharge is formed between the planar dielectric barrier plate 1322 and the probes (see Figure 12).
  • the reactive and energetic components or species of the plasma are repeatedly aspirated into the probes, using the fluid handling devices' aspirating and dispensing capabilities. The aspiration volume, rate and frequency are determined by the desired amount of cleaning/sterilization required.
  • the microplate format 1320 of Figure 13B may further comprise a vacuum system (not shown) to substantially remove any volatized contaminants and other products from the plasma that may deposit onto the planar dielectric barrier plate 1322 during the cleaning process.
  • a vacuum system not shown

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  • Physical Or Chemical Processes And Apparatus (AREA)
  • Cleaning In General (AREA)
  • Plasma Technology (AREA)

Abstract

L'invention porte sur un procédé et sur un appareil de nettoyage et de conditionnement de surfaces d'objets par plasma. Selon une première forme d'exécution, l'invention concerne un appareil de nettoyage par plasma d'objets conducteurs comprenant au moins une plaque barrière diélectrique plane présentant une première surface et une seconde surface, et au moins une électrode proche de la seconde surface de la plaque barrière diélectrique plane. La plaque barrière diélectrique plane est positionnée de façon à recevoir au moins un objet sensiblement et orthogonalement proche de la première surface. Selon une autre forme d'exécution, l'appareil comprend un plan de sol pour le nettoyage d'objets non conducteurs, ce plan de sol comportant des orifices dont la taille et la conception permettent de recevoir chaque objet à nettoyer.
PCT/US2006/021308 2005-06-02 2006-06-02 Procede et appareil de nettoyage et de conditionnement de surfaces d'objets par plasma WO2006130779A2 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US11/143,083 2005-06-02
US11/143,552 2005-06-02
US11/143,083 US20060272674A1 (en) 2005-06-02 2005-06-02 Method and apparatus for cleaning and surface conditioning objects using plasma
US11/142,988 US8092643B2 (en) 2003-06-16 2005-06-02 Method and apparatus for cleaning and surface conditioning objects using plasma
US11/142,988 2005-06-02
US11/143,552 US20060272675A1 (en) 2005-06-02 2005-06-02 Method and apparatus for cleaning and surface conditioning objects using plasma

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WO2006130779A2 true WO2006130779A2 (fr) 2006-12-07
WO2006130779A3 WO2006130779A3 (fr) 2007-02-01

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PCT/US2006/021309 WO2006130780A2 (fr) 2005-06-02 2006-06-02 Procede et appareil de nettoyage et de traitement de surface d'objets a l'aide d'un plasma

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CN108905545A (zh) * 2018-09-11 2018-11-30 北京振戎融通通信技术有限公司 可自动清洗介质阻挡放电管的低温等离子体废气处理部件
CN113357111A (zh) * 2021-07-01 2021-09-07 兰州空间技术物理研究所 一种离子推力器探针安装方法

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US6283130B1 (en) * 1995-05-30 2001-09-04 Anelva Corporation Plasma cleaning method and placement area protector used in the method
US20020124867A1 (en) * 2001-01-08 2002-09-12 Apl Co., Ltd. Apparatus and method for surface cleaning using plasma
US6666928B2 (en) * 2001-09-13 2003-12-23 Micell Technologies, Inc. Methods and apparatus for holding a substrate in a pressure chamber

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US6283130B1 (en) * 1995-05-30 2001-09-04 Anelva Corporation Plasma cleaning method and placement area protector used in the method
US20020124867A1 (en) * 2001-01-08 2002-09-12 Apl Co., Ltd. Apparatus and method for surface cleaning using plasma
US6666928B2 (en) * 2001-09-13 2003-12-23 Micell Technologies, Inc. Methods and apparatus for holding a substrate in a pressure chamber

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CN108905545A (zh) * 2018-09-11 2018-11-30 北京振戎融通通信技术有限公司 可自动清洗介质阻挡放电管的低温等离子体废气处理部件
CN113357111A (zh) * 2021-07-01 2021-09-07 兰州空间技术物理研究所 一种离子推力器探针安装方法
CN113357111B (zh) * 2021-07-01 2022-03-18 兰州空间技术物理研究所 一种离子推力器探针安装方法

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WO2006130780A2 (fr) 2006-12-07
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