US3771058A - Scanner element for coulter particle apparatus - Google Patents

Scanner element for coulter particle apparatus Download PDF

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Publication number
US3771058A
US3771058A US00131361A US3771058DA US3771058A US 3771058 A US3771058 A US 3771058A US 00131361 A US00131361 A US 00131361A US 3771058D A US3771058D A US 3771058DA US 3771058 A US3771058 A US 3771058A
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United States
Prior art keywords
aperture
wafer
wall
scanner element
tube
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Expired - Lifetime
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US00131361A
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English (en)
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W Hogg
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Coulter Electronics Inc
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Coulter Electronics Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/10—Investigating individual particles
    • G01N15/1031—Investigating individual particles by measuring electrical or magnetic effects
    • G01N15/12—Investigating individual particles by measuring electrical or magnetic effects by observing changes in resistance or impedance across apertures when traversed by individual particles, e.g. by using the Coulter principle
    • G01N15/13—Details pertaining to apertures

Definitions

  • the scanner element or aperture tube of a Coulter particle apparatus has a wafer in which the aperture is formed, the wafer being made of a material which has electrical insulating properties but high heat conductivity.
  • the tube is of glass and the wafer is set into the side wall of the tube. The result is a scanner element of increased sensitivity.
  • the surfaces of the tube, at least in the vicinity of the wafer are covered by a coating of highly conductive material coming close to but not engaging within the aperture of the wafer.
  • the coating inside and outside of the tube will comprise electrodes in the bodies of liquid respectively disposed on opposite sides of the tube wall.
  • the basic Coulter apparatus is disclosed in U.S. Pat. No. 2,656,508.
  • the apparatus includes a body of sample. suspension retained in vessel of insulating material and a so-called aperture tube immersed in the vessel.
  • the aperture tube has a small wafer set into its wall close to the bottom of the tube, which is usually made of glass, the wafer commonly being made of corundum, and the interior of the aperture tube is filled with liquid also.
  • the usual arrangement includes a closed liquid system of which the interior of the aperture tube comprises a part. Such a system is disclosed in U.S. Pat. No.
  • 2,869,078 provides for means to cause the flow of the suspension from the outer vessel through the aperture in theaperture tube while an electric current also flows through the aperture.
  • an electronic detector which is coupled to the respective bodies of liquid on the interior and exterior of the aperture tube by means of metal electrodes immersed in the respective bodies of liquid. The source of electric current is also connected to these electrodes.
  • the aperture which is formed in the aperture tube is a minute hole in a corundum wafer thatis set into the wall of the tube.
  • the aperture tube becomes a scanner element since it scans the liquid flowing through its aperture and produces a measurable signal each time that a particle passes through.
  • the construction of the aperture tube and one method of setting the wafer into the side wall of the tube are disclosed in U.S. Pat. Nos. 2,985,830 and 3,l22,43l.
  • sensing zone is the volume of electrolyte whose impedance is changed by the presence of a particle. If the energy in the sensing zone is provided by a low frequency source of electrical current and the effective electrical impedance of the particles is several orders of magnitude removed from that of the electrolyte (which is practically the case most of the time), then the change in impedance of the effective volume of the sensing zone by the introduction of the particle thereinto will produce a signal which can be detected which.
  • the types of particles which have been analyzed by means of the Coulter apparatus cover a very wide gamut and include biological and industrial particles, as well-known in this art.
  • an aperture diameter to provide fairly linear output for the largest particles which are expected to be involved, but this choice is a compromise with the desire to detect the smallest useful particles as well. In the latter case, the aperture cannot be too large because its sensitivity decreases with increase in size. This should be obvious since the current density decreases for larger apertures.
  • the length of the aperture is generally made about to 100 percent of its diameter, primarily to give the central region of the electric field within the aperture an opportunity to become fairly uniform. It has been mentioned above that the field bulges at the ends of the aperture giving effects which decrease the sharpness of the signal and its uniformity.
  • the average length of an aperture is about percent of its diameter.
  • Increased resistance in the aperture will generatemore socalled Johnson noise than a lower resistance of a shorter path thus cancelling the gain to be achieved due to decreased bandwidth of the ampli'fiero
  • the increased resistance also is part of the problem of heating of the electrolyte as it passes through the aperture.
  • the current density in the aperture is very high and the electrolyte remains under this influence for a longer time than in the case of shorter apertures. Heating of the electrolyte will cause it to produce noise components of a random nature above "the normal Johnson noise limiting the size of particles which can be detected to those which are large enough to produce signals greater than the noise.
  • the temperature of the electrolyte rise above the boiling 'point, small bubbles will be generated in the aperture and these appear as particles to the detector.
  • the electrical signal generated by the passage of a particle is proportional to the intensity of the aperture current. If these were the only considerations, it would be possible to detect any particle so long as it exceeded by several orders of magnitude the ionic dimensions of the electrolyte used, and displaced enough ions to cause a discernible change over and above the random fluctuation in the number of ions in'thesensing zone. The heating of the electrolyte, however, eventually limits the usefulness of increased aperture current as will be seen hereinafter.
  • the type of aperture which is best used in Coulter apparatus is one which has a sharpedged inlet.
  • both ends of the wafers sharp-edged because of the practical problems of identifying which is the sharp-edged entrance in the case only one end were sharp-edged.
  • These types of apertures are easy to clear in the event that debris becomes lodged in them, which is just the opposite of wafers that have funnel-shaped entrances. The sharp-edged wafers are easier to manufacture and inspect.
  • the effect of such sharp-edged inlets upon the flow of liquid through the aperture is to produce a pattern of flow that is known as vena contracta.
  • the flow pattern commences to constrict at the entrance and grows progressively smaller downstream of the entrance, leaving a space between the vena contracta and the wall of the aperture in which the electrolyte has no definite velocity, certainly not the average velocity of the stream passing through the axis of the aperture.
  • the electrolyte in this region has eddy currents in it, tha part being swept out by reason of proximity to the vena contracta being replaced by electrolyte which enters the region from the downstream end of the aperture next to its walls.
  • This effectively stagnant region has no organized flow pattern and has substantially less motion than the main flow of liquid.
  • the signal-to-noise ratio of the Coulter apparatus improves linearly with aperture current for small aperture currents since the noise is constant whereas the signal developed is proportional to aperture current. Sensitivity also increases. The point is reached, however, at which in addition to the Johnson noise, noise due to the heating effects described above, increase at the same rate as the signal, beyond which point no further improvement is gained in the signal-to-noise ratio. As a matter of fact, noise increases more rapidly than the signal after this latter mentioned point is reached so that the signal-to-noise ratio is instead worsened.
  • the invention herein provides a structure for a scanner element which results in cooling the electrolyte located in the region on quasi-stagnation, thereby lessening the degree of modulation of resistance for a given aperture current. Absent the heating noise, sensitivity and signal-tonoise ratio are substantially improved with the result that a given aperture is capable of distinguishing between very much smaller particles than have heretofore been detected by the normal Coulter apparatus. It can be seen that an entire new field of particle technology can be opened by theinvention.
  • the scanner element of the invention is characterized by the provision of an aperture wafer that is formed of a hard material that is insulative with respect to the electrical current flowing in the aperture but which has high thermal conductivity. Accordingly, the wall of the aperture conducts heat away from the aperture thereby cooling the electrolyte in the quasistagnant region that is in closest contact with the wall.
  • the wafer itself and the electrolyte in contact with it may function as a heat sink.
  • metallic means may be used in contact with the wafer to serve as a heat conduit.
  • the material of the wafer in addition to the above qualities, must be capable of securement to the wall of anaperture tube by some suitable means.
  • the example described herein is beryllium oxide.
  • FIG. 1 is a diagrammatic view illustrating lines of flow of a liquidthrough an aperture of any type
  • FIG. 2 is a fragmentary sectional view through a "scanner-element of the invention illustrating one ing-"the aperture wafer to the side wall;
  • FIG. 3 is a fragmentary front elevational view of the FIG. 4 is a fragmentary sectional view through a scanner element showing another method of securing the aperture wafer to the side wall thereof;
  • FIG. 5 is a fragmentary sectional view through a modified form of scanner element.
  • FIG. 6 is a diagrammatic view showing a conventional Coulter apparatus setup using a scanner element of the invention.
  • the flow of. liquid through such an aperture 14 is characterized by a flow field illustrated, the flow of FIG. I being assumed to be in the direction of the arrows. Jet contraction and flow curvatures are produced by the radial approach of fluid to the aperture 14, this being illustrated in region 16 after which the streamlines become essentially straight and parallel at a section termed the vena contracta a short distance downstream from the entrance 12.
  • the vena contracta is shown at approximately the region 18 but it may well occur within the bore of the aperture 14 shortly after the liquid has passed the entrance 12.
  • the principal flow of liquid through the aperture 14 is radially inward of the aperture wall 20 thereby producing a region of turbulence or quasi-stagnation at 22.
  • Liquid is detached from the downstream end of the main flow to replace electrolyte drawn into the flow as indicated by the small arrows 24. It is in this region 22 that heating noise is produced as the aperture current is increased due to thefact that the time that increments of electrolyte remain in the aperture 14 in these regions 22 is much greater and more variable than the time that an increment in the principal flow remains in the aperture.
  • FIGS. 2 and 3 illustrate a scanner element 26 which is constructed in accordance with the invention.
  • a tube 28 made of a principally transparent material such as glass.
  • the glass wall of the tube is designated 30 and any of the known techniques may be used to prepare the wall 30 for receiving the aperture wafer.
  • the wafer 32 in FIGS. 2 and 3 has been fused into the outer surface of the wall 30 immediately over a large orifice 34 that is formed in the wall 30.
  • the wafer 32 has a central aperture 36 not much different in configuration than the aperture 14 of FIG. 1 and probably formed in the wafer 32 by similar technique.
  • the wafer 32 is made of a meterial which is electrically insulative and yet heat-conductive such as, for example, beryllium oxide or diamond.
  • beryllium oxide is preferred, since it is relatively inexpensive, about the same hardness as corundum, its thermal conductivity is greater than that of many metals and it is easy to handle and fuse to glasses having the same or slightly greater coefficients of thermal expansion, such as some soda-lime glasses. It is desirable for the glass to have slightly higher rates of expansion so that the beryllium oxide is in compression when the assembly cools. In case of apertures substantially.
  • the wafer 32 will serve as a heat sink together with the electrolyte which contacts the same and draws heat from the region of quasi-stagnancy such as 22 illustrated in FIG. 1.
  • This cooling effect decreases heat noise and enables higher aperture currents to be used with resulting increased sensitivity to smaller particles.
  • FIG. 4 illustrates a similar wafer 32 but in this case the wafer is secured to the outer surface of the wall 30 by means of an adhesive 38 such as, for example, an epoxy type.
  • an adhesive 38 such as, for example, an epoxy type.
  • Some epoxy type adhesives have very high thermal conductivity and good electrically insulative properties.
  • FIG. 5 illustrates a scanner element 40 having an orifree 42 in its wall 44 and having an aperture wafer 46 fused into the wall over the orifice.
  • the aperture wafer 46 has a central aperture 48 and the material from which the wafer 46 is made has good electrically insulative properties and high thermal conductivity.
  • the aperture 48 is of the order of 100 microns or greater.
  • a metallic coating is shown at 50 on the exterior and 52 on the interior of the wall 44 with portions 54 and 56 overlying the surface of the wafer 46 and being in intimate contact therewith. Such coatings could also be in the form of wires, strips or bars.
  • the heat generated in the aperture 48 is conducted by the wafer 46 and the metallic members 54 and 56 to the electrolyte which is disposed on both sides of the wall 44.
  • These metallic heat-conducting members 50 and 52 need not be connected to the electrodes leading; to the detector of Coulter particle device.
  • the metallic coatings or connections serve as conduits of heat, drawing same from the wafer to the electrolyte bodies. They may also serve as such electrodes and be connected as shown by leads 58 to the Coulterparticle device.
  • the full coating is especially useful in case of high frequency aperture current as disclosed in said copending application.
  • the copending application illustrates a form of scanner element or aperture tube in which the walls are made of synthetic resin enclosed within metallic tubes that serve as the inner and outer electrodes.
  • the wafer used is required to be set into the wall of the aperturetube in a suitable cavity provided such as, for example, at the bottom end. This may also be done with an aperture wafer of the material disclosed herein.
  • the invention may be embodied in scanner elements of many different constructions.
  • the wafers of the invention may be utilized in continuous flow structures and, in fact, practically anywhere that a Coulter scanner element is used.
  • FIG. 6 shows a conventional arrangement using an aperture tube such as 26 with an aperture wafer 32 in the side wall thereof near the lower end, set into a vessel 60 having a suspension 62 of particles therein.
  • the interior of the aperture tube 26 has a second body of fluid 64 therein and is connected into a system of the type disclosed in US. Pat. No. 2,869,078.
  • Electrodes 66 and 68 connect to the Coulter particle analyzing device 70.
  • the suspension 62 flows through the aperture of the wafer 32 to the body of fluid 64 and passage of particles is detected by the apparatus 70.
  • the Wall of the aperture tube 26 by transparent so that the image of the aperture 36 may be optically projected onto some surface for viewing during use.
  • a scanner element including a wall of electrically insulative material having an orifice therein and a wafer being of a flat disc configuration and having an aperture therein secured to said wall over said orifice whereby liquid flow from one side of the wall to the other will pass through said aperture, while an electric current also flows through the aperture, a signal being produced each time a particle passes through the aperture, said wafer being of a material of electrically insulative property and thermal conductivity of at least 50 Btu/hr/sq ft/F/ft, such as to reduce excessive noise in the aperture, improve the signal-to-noise ratio, and increase sensitivity of the scanner element.
  • the scanner element as claimed in claim 2 which the wafer is formed of an oxide of beryllium.
  • a scanner element which comprises a wall of insulating material having an orifice therein, a substantially inert wafer having a flat disc configuration and being of electrically insulative material and having thermal conductivity of at least 50 Btu/hr/sq ft/F/ft and having an aperture therein secured to said wall in face-to-face engagement and with the aperture and orifice aligned, wherein excessive noise in the aperture is reduced, the signal-tonoise ratio is improved, and the sensitivity of the scanner elmement is increased.
  • An aperture tube for use with a Coulter particle apparatus comprising an elongate glass tube having an orifice in its wall adjacent the lower end thereof, an electrically insulative wafer being of a flat disc configuration and having thermal conductivity of at least 50 Btu/hr/sq ft/F/ft engaged to said wall and blocking said orifice and there being a through aperture in said wafer aligned with said orifice, wherein excessive noise in the aperture is reduced, the signal-to-noise ratio is improved, and the sensitivity of the aperture tube is increased.

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  • Chemical & Material Sciences (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
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  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
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US00131361A 1971-04-05 1971-04-05 Scanner element for coulter particle apparatus Expired - Lifetime US3771058A (en)

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US13136171A 1971-04-05 1971-04-05

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US (1) US3771058A (ja)
JP (1) JPS5247716B1 (ja)
CA (1) CA965481A (ja)
CH (1) CH557534A (ja)
FR (1) FR2136054A5 (ja)
GB (1) GB1353884A (ja)
SE (1) SE382502B (ja)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3924180A (en) * 1973-10-12 1975-12-02 Us Energy Potential sensing cell analyzer
US4760328A (en) * 1986-05-05 1988-07-26 Integrated Ionics, Inc. Particle counter having electrodes and circuitry mounted on the pane of the orifice
US5402062A (en) * 1993-12-23 1995-03-28 Abbott Laboratories Mechanical capture of count wafer for particle analysis
US5432992A (en) * 1993-12-23 1995-07-18 Abbott Laboratories Method of making count probe with removable count wafer
US5500992A (en) * 1993-12-23 1996-03-26 Abbott Laboratories Method of making stress relieved count probe
WO1997024600A1 (en) * 1995-12-29 1997-07-10 Ian Basil Shine Electrode assembly
US6111398A (en) * 1997-07-03 2000-08-29 Coulter International Corp. Method and apparatus for sensing and characterizing particles
US6175227B1 (en) 1997-07-03 2001-01-16 Coulter International Corp. Potential-sensing method and apparatus for sensing and characterizing particles by the Coulter principle
US6259242B1 (en) 1999-05-26 2001-07-10 Coulter International Corp. Apparatus incorporating a sensing conduit in conductive material and method of use thereof for sensing and characterizing particles
US20070172386A1 (en) * 1999-06-22 2007-07-26 Jiali Li Ion beam sculpting of multiple distinct materials
US20100271053A1 (en) * 2009-04-24 2010-10-28 Beckman Coulter, Inc. Method of Characterizing Particles

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2861932A (en) * 1957-03-06 1958-11-25 Rauland Corp Method of treating semi-conductor articles
US2985830A (en) * 1958-12-29 1961-05-23 Coulter Electronics Scanner element for particle analyzers
US3238452A (en) * 1961-10-18 1966-03-01 Union Oil Co Apparatus and method for detecting contaminants in a fluid
US3266526A (en) * 1962-11-26 1966-08-16 Robert H Berg Peripherally locked and sealed orifice disk and method
US3345561A (en) * 1963-09-26 1967-10-03 Sperry Rand Corp Mount for supporting dual bolometers at same temperature
US3457501A (en) * 1966-08-18 1969-07-22 Maxwell Ingram Probe for measuring conductivity of an electrolyte solution
US3628140A (en) * 1969-11-06 1971-12-14 Coulter Electronics Scanning element and aperture wafer for electronic particle counting and sizing apparatus

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2861932A (en) * 1957-03-06 1958-11-25 Rauland Corp Method of treating semi-conductor articles
US2985830A (en) * 1958-12-29 1961-05-23 Coulter Electronics Scanner element for particle analyzers
US3238452A (en) * 1961-10-18 1966-03-01 Union Oil Co Apparatus and method for detecting contaminants in a fluid
US3266526A (en) * 1962-11-26 1966-08-16 Robert H Berg Peripherally locked and sealed orifice disk and method
US3345561A (en) * 1963-09-26 1967-10-03 Sperry Rand Corp Mount for supporting dual bolometers at same temperature
US3457501A (en) * 1966-08-18 1969-07-22 Maxwell Ingram Probe for measuring conductivity of an electrolyte solution
US3628140A (en) * 1969-11-06 1971-12-14 Coulter Electronics Scanning element and aperture wafer for electronic particle counting and sizing apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Handbook of Chem. & Physics, 1966, p. E 4, 47 Ed., CRC. *

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3924180A (en) * 1973-10-12 1975-12-02 Us Energy Potential sensing cell analyzer
US4760328A (en) * 1986-05-05 1988-07-26 Integrated Ionics, Inc. Particle counter having electrodes and circuitry mounted on the pane of the orifice
US5402062A (en) * 1993-12-23 1995-03-28 Abbott Laboratories Mechanical capture of count wafer for particle analysis
US5432992A (en) * 1993-12-23 1995-07-18 Abbott Laboratories Method of making count probe with removable count wafer
US5500992A (en) * 1993-12-23 1996-03-26 Abbott Laboratories Method of making stress relieved count probe
WO1997024600A1 (en) * 1995-12-29 1997-07-10 Ian Basil Shine Electrode assembly
AU699852B2 (en) * 1995-12-29 1998-12-17 Ian Basil Shine Electrode assembly
US6084392A (en) * 1995-12-29 2000-07-04 Shine; Thomas Adam Electrode assembly
US6111398A (en) * 1997-07-03 2000-08-29 Coulter International Corp. Method and apparatus for sensing and characterizing particles
US6175227B1 (en) 1997-07-03 2001-01-16 Coulter International Corp. Potential-sensing method and apparatus for sensing and characterizing particles by the Coulter principle
US6259242B1 (en) 1999-05-26 2001-07-10 Coulter International Corp. Apparatus incorporating a sensing conduit in conductive material and method of use thereof for sensing and characterizing particles
US20070172386A1 (en) * 1999-06-22 2007-07-26 Jiali Li Ion beam sculpting of multiple distinct materials
US7258838B2 (en) * 1999-06-22 2007-08-21 President And Fellows Of Harvard College Solid state molecular probe device
US20100271053A1 (en) * 2009-04-24 2010-10-28 Beckman Coulter, Inc. Method of Characterizing Particles
WO2010124202A1 (en) * 2009-04-24 2010-10-28 Beckman Coulter, Inc. Method of characterizing particles
US8395398B2 (en) * 2009-04-24 2013-03-12 Beckman Coulter, Inc. Method of characterizing particles

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FR2136054A5 (ja) 1972-12-22
DE2214903B2 (de) 1975-08-14
GB1353884A (en) 1974-05-22
CH557534A (fr) 1974-12-31
DE2214903A1 (de) 1972-10-19
JPS5247716B1 (ja) 1977-12-05
SE382502B (sv) 1976-02-02
CA965481A (en) 1975-04-01

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