US3654439A

US3654439A - Particle counting apparatus having automatic display and threshold setting

Info

Publication number: US3654439A
Application number: US32583A
Authority: US
Inventors: Weems E Estelle; Pasquale M Petrucci
Original assignee: GENERAL SCIENCE CORP
Current assignee: Biochem Immunosystems US Inc; GENERAL SCIENCE CORP
Priority date: 1970-04-28
Filing date: 1970-04-28
Publication date: 1972-04-04
Anticipated expiration: 1989-04-04
Also published as: GB1351586A

Abstract

Particle counting apparatus especially adapted for blood cell counting and which is essentially automatic in operation. Coded sample flasks are employed in conjunction with a counter display to automatically set the appropriate decimal point for corresponding red or white count magnitude and to also provide automatic threshold settings for red and white cell counts.

Description

United States Patent Estelle et al. [4 1 Apr. 4, 1972 s41 PARTICLE COUNTING APPARATUS UNITED STATES PATENTS HAVING AUTOMATIC DISPLAY AND 3,020,749 2/1962 Cropper et al. ..235/92 SH THRESHOLD SETTING 2,674,675 4/1954 Lambert ..340/280 [72] Inventors: Weems E. Estelle, Southport; Pasquale M. 3441352 4/ 1969 Hughesm "356/39 x Petrucci, Orange, both of Conn. Primary Examiner Daryl Cook [73] Assignee: General Science Corp., Bridgeport, Conn. Assistant Examiner-Joseph The,

Attorney-Joseph Weingarten [22] Filed: Apr. 28, 1970 21 Appl. N0.: 32,583 [57] ABSTRACT Particle counting apparatus especially adapted for blood cell 52 us. 0 .235/92 PC, 235/92 R, 235/92 EA, and essemauy r 340/280 324/71 CP 356/39 Coded sample flasks are employed in con unction with a Int Cl H03k 21/18 counter display to automatically set the appropriate decimal point for corresponding red or white count magnitude and to [58] Field of Search "235/92 EA'92 92 92 also provide automatic threshold settings for red and white 235/643, 61 DP, 94; 340/280; 356/39; 324/71 CP cell counts.

[56] References Cited 5 Claims, 5 Drawing Figures LOGIC CIRCUITRY PATVENITEDAPR 4 m2 3,654,439

' SHEETIUFZ 32 34 @5 16 & 5

LOGIC CIRCUITRY DISPLAY INDICATORS 44 T4 I 46 Fig. 1.

INVIIN'H )RS WEEMS E. ESTELLE PASQUALE M PE TRUCCI PATENTEDAFR 41972 SHEET 2 0F 2 IN VEN'I )RS WEEMS E. ESTELLE I v PASOUALE M PETRUCCI ORNFYS PARTICLE COUNTING APPARATUS HAVING AUTOMATIC DISPLAY AND THRESHOLD SETTING FIELD OF THE INVENTION BACKGROUND OF THE INVENTION Systems are known for counting particles suspended in a liquid, a major application of such systems being the counting of red and white blood cells. In general, such particle counting systems include a pair of electrodes disposed within a fluid path and having an aperture disposed therebetween through which the particle-containing fluid flows. The impedance of the fluid path as sensed by the electrodes is materially altered by the presence of a particle within the aperture, giving rise to electrical pulses which can be electrically counted and which correspond to the number of particles passing through the aperture. Means are usually employed for metering a known volume of particle-containing liquid such that a particle count for a known volume of liquid can be provided.

Particle counting systems of known construction are usually quite complex and rather expensive, and the high cost of conventional systems limits their availability to many who would otherwise have use for such systems. In addition, known systems often require many manipulative steps during operation in order to provide the requisite analysis, and are often difficult to calibrate. Moreover, the aperture through which particles are caused to flow is usually formed with a glass vessel, and is not easily accessible for cleaning or adjustment.

SUMMARY OF THE INVENTION In accordance with the present invention, a sophisticated and yet relatively simple particle counting system is provided which is especially adapted for blood cell counting and which is substantially automatic in operation. The system includes coded sample flasks or bottles which are operative to automatically set the appropriate threshold for red of white cell counting and to also set an appropriate decimal point of an output counter to display a correct count magnitude.

A system embodying the invention includes a conductivity cell having a pair of electrodes and an easily adjustable and interchangeable aperture disposed between the electrodes and sized to accommodate the blood cells or other particles under analysis. A photosensitive metering technique is employed to determine the volume of liquid which is to be analyzed. The passage of particles through the aperture of the conductivity cell alters the impedance of the path through the aperture, and the change in impedance causes a corresponding change in voltage level which is sensed by a high input impedance, low noise, high gain amplifier. Threshold detection circuitry is provided to discriminate against pulses below a predetermined threshold level caused by noise and other spurious conditions.

A separate sample flask is provided for red cell and white cell samples, and each flask is uniquely coded to automatically set respective threshold levels and count magnitude displays upon insertion of a flask into the system. Insertion of a red cell flask into the system causes an appropriate threshold level to be set and also causes illumination of an appropriate decimal point indicator and red cell count indicator for display of the proper count magnitude for red cells. Insertion of a white cell flask similarly determines the count magnitude and threshold level suitable for a white cell count.

DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a particle counting system according to the invention;

FIG. 2 is a pictorial view, partly in section, illustrating a conductivity cell embodied in the invention;

FIG. 3 is a pictorial view, partly in phantom, of a particle counting system according to the invention;

FIG. 4 is a cutaway pictorial view of the sample flask coding apparatus embodied in the invention; and

FIG. 5 is a pictorial view of a sample flask according to the invention.

DETAILED DESCRIPTION OF THE INVENTION A particle counting system which is especially adapted for counting blood cells is illustrated in diagrammatic form in FIG. 1. The particles to be counted are suspended within a liquid contained within a sample flask l0, and fluid is drawn from flask 10 into the system by means of a tube I2. The particle-containing fluid is drawn from flask 10 by way of tube 12 to the input orifice of a conductivity cell 14 which includes a pair of electrodes with an aperture disposed therebetween and through which the fluid to be analyzed flows. The conductivity cell per se will be described in detail hereinafter.

Conductivity cell 14 is coupled to a flow tube 16 which terminates in a waste bottle 18. A suction pump 20 is also coupled to waste bottle 18 through a-suitably sealed stopper 22 and is operative to draw sample fluid from flask 10 through conductivity cell 14 and flow tube 16 for analysis. A pair of electrodes 24 are disposed within waste bottle 18 and are coupled to logic circuitry 26 for the detection of a predetermined upper level of waste fluid within bottle 18 to prevent overflow of waste fluid from the bottle and to also prevent the entry of waste fluid into suction pump 20.

A first photosensor 28 is disposed adjacent flow tube 16 at a predetermined position along the length thereof and a second photosensor 30 is similarly disposed with respect to flow tube 16 in a position downstream from first photosensor 28. Flow tube 16 is formed of a suitable light transmissive material such as glass and a pair of

light sources

32 and 34 are arranged in operative association with

respective photosensors

28 and 30. The photosensorsare connected to logic circuitry 26 and are employed to provide electro-optical metering of the volume of liquid to be analyzed. In the absence of fluid flowing within tube 16,

photosensors

28 and 30 receive light from

respective sources

32 and 34. During the passage of fluid within tube 16, however, the

respective photosensors

28 and 30 do not receive light from their respective illumination sources. An electrical output signal is thus provided to logic circuitry 26 by

photosensors

28 and 30 depending upon the presence of fluid at the sensor locations. The particle counting operation is commenced and terminated by gating signals provided by this eIectro-optical metering system. The passage of fluid within tube 16 past photosensor 28 causes a signal to be applied to logic circuitry 26 to commence a counting operation, while the counting operation is terminated upon receipt of a signal from photosensor 30. In this manner, a counting run is accomplished on a metered volume of liquid determined by the internal dimensions of flow tube 16 and the distance between the

metering photosensors

28 and 30. The photosensitive metering technique itself is described in detail in copending US Pat. application Ser. No. 809,332, now US Pat. No. 3,577,162, entitled Automatic Particle Counting System and assigned to Contraves AG.

The

electrodes

36 and 38 of conductivity cell 14 are connected to an input amplifier 40 which is a high input impedance, low noise, high gain operational amplifier. The output of amplifier 40 is coupled to logic circuitry 26 and the logic circuitry is operative to provide an output indication of particle count on a suitable display 42 and to energize suitable alarm indicators 44. Operating controls 46 are coupled to logic circuitry 26 for enabling system operation.

The conductivity cell through which the sample fluid is caused to flow and in which the changes in impedance caused by the presence of particles within an aperture are detected is illustrated more particularly in FIG. 2. The cell 14 is of generally cylindrical configuration and typically is formed of a plastic material such as plexiglass or other polycarbonate plastic which is inert to the fluids being analyzed and which is electrically insulative. An aperture support 50, also typically formed of the same plastic material, is supported within a cylindrical opening coaxially provided at one end of the cell body 51 and is securely fitted therein such as by O-rings 54. An aperture through which the particle-containing fluid is caused to flow is formed within a ruby element 56 disposed within the side of support 50, with the aperture in alignment with an input passage 58 which communicates with input tube 60. A visual marking 53 is provided on an end of aperture support 50 and is located to indicate aperture alignment when the marking is facing vertically upward.

The aperture within ruby 56 also communicates with an opening 61 formed in the inner end of support 50 and which in turn communicates with a coaxial passage 62 formed within cell body 51. The electrode 36 is disposed within passage 58 and has an end adjacent the aperture element 56 and is connected to an electrical connector 64 formed within body 51. The second electrode 38 is disposed within the opening 61 formed in the end of support 50 and terminates in a second electrical connector 66 also formed within body 51.

Electrodes

36 and 38 are typically formed of platinum or other metal inert to the fluid under analysis.

Connectors

64 and 66 are coupled by suitable interconnecting wires to input amplifier 40, as illustrated in FIG. 1 and to a source of excitation voltage. The flow tube 16 is coupled to cell 14 by means of a coaxial opening 68 formed in the end of body 51 opposite to support 50 and also containing O-rings 70 for sealing. A passage 72 is coupled to fluid passage 62 and includes an enlarged end portion or port 74 which is cooperative with a plunger 76 (FIG. 1) to provide venting of the cell. The plunger 76 is coupled to the operated by an electrically driven solenoid 78 which is energized by logic circuitry 26.

The construction of conductivity cell 14 permits the easy adjustment of the metering aperture within the fluid passage and also permits relatively easy cleaning and replacement of the aperture within the cell. The entire cell which is easily installed and removed from the system, is electrically connected by means of

connectors

64 and 66, and fluid coupled by simple installation of the cell onto an end of flow tube 16 and of input tube 12 to input passage 60. During operation, fluid containing particles to be counted is drawn through passage 60, aperture element 56 and thence via passage 62 into flow tube 16. Vent port 74 is closed by plunger 76 during an analytical run so that fluid is drawn by suction pump through the system for the counting of particles therein. After a count has been accomplished, plunger 76 is automatically withdrawn from the associated port 74 to cause air to be drawn into the cell by operation of pump 20. The system is automatically purged after completion of a counting run and is thus in condition for a subsequent analytical run.

Automatic purging of fluid from the cell and the system after an analytical run offers major advantages over particle counting systems of conventional design. As discussed, opening of the conductivity cell vent after a counting run causes air to be drawn into the cell, with consequent purging of fluid within

passages

61 and 62 of cell 14 and within flow tube 16. As a result of this purging operation, no fluid remains within the otherwise conductive path formed between

electrodes

36 and 38 and the aperture disposed therebetween, and thus no conduction between electrodes occurs An excitation voltage applied to the cell electrodes need not therefore be removed, as in conventional systems, since no fluid is present to permit conduction. Excitation is thus continuously applied to the electrodes when the system is energized but conduction within the conductivity cell occurs only during an analytic run.

The absence of conduction after the system is vented also prevents electrolysis and consequent production of gas bubbles during the time between runs. Such lack of conduction also permits the use of smaller electrodes as the conductivity of the electrodes is not materially diminished by formation of gas bubbles on the surface thereof, such as can occur to a greater extent in conventional systems. It should be noted that although residual fluid may remain by capillary action within input passage 58, this residual fluid is not analyzed during a subsequent run since the actual fluid to be analyzed will flow through the cell aperture before a start signal is provided by photosensor 28.

The novel system is packaged within a compact housing which is of a size and configuration adapted for desk top operation. The general packaging arrangement is illustrated in FIG. 3. The conductivity cell 14 and its associated flow tube 16 are arranged in the illustrated embodiment on the righthand side of the cabinet 86 with

metering photosensors

28 and 30 and associated

light sources

32 and 34 being contained within

respective housings

31 and 33 disposed around flow tube 16. Tube 16 is coupled via tubing 80 to waste bottle 18 which is also coupled via tubing 82 to suction pump 20 and associated flow regulator 84 for providing a uniform flow rate. The sample flask 10 is inserted within the system in the manner illustrated with input tube 12 disposed within flask 10 for withdrawal of fluid therefrom into cell 14.

The instrument cabinet 86 includes a section on the righthand side thereof having an opening for simple insertion of sample flask l0, and an upper opening for easy access to aperture support 50 of conductivity cell 14 for the adjustment or replacement of the metering aperture. A nozzle is coupled from pump 20 to the front panel of housing 86 to provide a source of positive air pressure for blowing out support 50 and the aperture therein. Support50 is placed coaxially onto nozzle 95 to clear the aperture. The controls and indicators are contained on instrument housing 86 and include a count control 90, calibrate control 92, verify indicator 94, on-off control 96 and waste indicator 98. In the illustrated embodiment, the controls are of the selfilluminating pushbutton type.

The particle count is displayed on a three digit electromechanical counter which includes digital output indicator wheels 100; a white blood cell indicator 102 and red blood cell indicator 104 are provided to denote which cell count is being displayed and to display the appropriate multiplier for the cell count. Fiberoptic or other

light transmitting cables

106 and 108 are respectively coupled from the lamps associated with

indicators

102 and 104 to positions between the digits of indicator 100 to provide selective decimal point indication depending upon whether a red blood cell count or a white blood cell count is being performed. As will be described, the decimal point is automatically set by insertion of an appropriate red cell or white cell flask 10 into the system.

The counter assembly and the decimal point coding arrangement is illustrated in greater detail in FIG. 4. The electrornechanical counter is itself well-known and includes digit wheels 100 driven by actuating relays. The respective digits being displayed and visible through a suitable window on the instrument housing. The

indicators

102 and 104 include a respective appropriately labeled window, as illustrated, and a respective associated

light source

103 and 105 disposed therebelow. Fiberoptic cable 106 is coupled between the light source 103 and a position between the second and third digit wheels 100 of the counter. Fiberoptic cable 108 is coupled between light source 105 and a position between the first and second digit wheels of the counter. The

light sources

103 and 105 are electrically connected to microswitch 112 which includes an actuating arm 113 adapted to be selectively engaged by a sample flask 10 inserted within the input opening of the cabinet 86. With switch 112 in one position, indicator 102 is illuminated as is decimalpoint 116 to provide display of a white cell count magnitude. With switch 112 in its second position, indicator 104 and associated decimal point 114 are illuminated to provide suitable display of a red cell count magnitude.

The sample flask 10 is selectively coded for red and white cell counting. The red cell counting flask is coded as illustrated in FIG. 4 with a flange 110 formed on the end thereof near the noule 111 and operative to engage the switch arm 113 to cause setting of switch 112 to a position to enable red cell indicator 104 and decimal point 114. The sample flask 10a (FIG. 5) employed for white cell counting does not include the end flange 110, and as a result, with a white sample flask inserted within the instrument, switch 112 remains in a second position causing illumination of white blood cell indicator 102 and associated decimal point 116. For convenience of use, the sample flasks can include a handle 115 and can be color coded for red cell and white cell counting. Typically the red cell and white cell flasks are respectively red and white, and can be respectively prediluted to a predetermined degree such that only a measured quantity of blood need be supplied to the respective flasks to prepare a sample for analysis.

The input tube 116 which is inserted within the sample flask is attached to a block 117 which is pivotally mounted for rotation about an axis defined by mounting screws on the sides thereof. Tube 116 communicates with a passage provided through block 117 and is coupled to cell 14 via a flexible tube 118. In the absence of the flask within the housing, block 117 is maintained in a vertical position by a spring member 119. As a result, input tube 116 extends forwardly in a substantially horizontal disposition for easy insertion into nozzle 111 of a sample flask. After a flask is placed onto tube 116 and is seated within the opening provided within housing 86, block 117 and tube 116 are rotated as illustrated to accommodate for the angular disposition of the input tube within flask 10.

It is not intended to limit the invention by what has been particularly shown and described, except as indicated in the appended claims.

What is claimed is:

1. In a particle counting system for counting blood cells suspended in a fluid including an aperture through which particle-containing fluid is caused to flow, threshold detection circuitry to discriminate against pulses below a predetermined threshold level, means for generating an electrical pulse for each blood cell passing through said aperture, means for counting said pulses above said predetermined threshold level and operative to provide an indication of the number of blood cells represented by said electrical pulses above said predetermined threshold level within a predetermined volume of fluid, apparatus comprising:

a display having a plurality of digit indicators, first and second decimal point indicators associated with said digit indicators and red cell and white cell indicators for respectively indicating a number which represents the multiplier of an associated cell count;

respective sample flasks for containing liquid for analysis and having a coded portion formed thereon for uniquely coding a red cell flask and a white cell flask;

a receptacle adapted to receive a sample flask inserted therein and having means operative in response to the coded portion of said flask to set said decimal point indicator and multiplier indicator corresponding to the type of cells to be analyzed, and also operative to set the appropriate threshold level in said particle counting system in accordance with the type of cells to be analyzed.

2. Apparatus according to claim 1 wherein said multiplier indicators each include an indicator panel containing a visual inscription of the corresponding multiplier thereon and a light source for illuminating said indicator panel; and

wherein said decimal point indicators each include a light conducting rod coupled between a respective decimal point position associated with said digit indicators and a respective one of said light sources.

3. Apparatus according to claim 1 wherein said receptacle means includes a switch having an arm disposed within said receptacle in a position to be selectively engaged by the coded portion of said sample flasks.

4. Apparatus according to claim 3 wherein said sample flasks are each of generally rectangular configuration having said coded portion on an end thereof adapted to selectively engage said switch arm.

5. Apparatus according to claim 3 wherein each of said flasks is of elongated configuration and having a spout formed on one end thereof from which fluid is drawn for analysis, said coded portion being on the end thereof near said spout, the

presence or absence of a flange formed on said coded portion representing the identity of cells to be analyzed and selectively actuating said switch arm accordingly to appropriately set said decimal point and multiplier indicators.

Claims

1. In a particle counting system for counting blood cells suspended in a fluid including an aperture through which particle-containing fluid is caused to flow, threshold detection circuitry to discriminate against pulses below a predetermined threshold level, means for generating an electrical pulse for each blood cell passing through said aperture, means for counting said pulses above said predetermined threshold level and operative to provide an indication of the number of blood ceLls represented by said electrical pulses above said predetermined threshold level within a predetermined volume of fluid, apparatus comprising: a display having a plurality of digit indicators, first and second decimal point indicators associated with said digit indicators and red cell and white cell indicators for respectively indicating a number which represents the multiplier of an associated cell count; respective sample flasks for containing liquid for analysis and having a coded portion formed thereon for uniquely coding a red cell flask and a white cell flask; a receptacle adapted to receive a sample flask inserted therein and having means operative in response to the coded portion of said flask to set said decimal point indicator and multiplier indicator corresponding to the type of cells to be analyzed, and also operative to set the appropriate threshold level in said particle counting system in accordance with the type of cells to be analyzed.

2. Apparatus according to claim 1 wherein said multiplier indicators each include an indicator panel containing a visual inscription of the corresponding multiplier thereon and a light source for illuminating said indicator panel; and wherein said decimal point indicators each include a light conducting rod coupled between a respective decimal point position associated with said digit indicators and a respective one of said light sources.

5. Apparatus according to claim 3 wherein each of said flasks is of elongated configuration and having a spout formed on one end thereof from which fluid is drawn for analysis, said coded portion being on the end thereof near said spout, the presence or absence of a flange formed on said coded portion representing the identity of cells to be analyzed and selectively actuating said switch arm accordingly to appropriately set said decimal point and multiplier indicators.