Particle counting apparatus utilizing various fluid resistors to maintain proper pressure differentials
First Claim
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1. Apparatus for counting particles in a liquid suspension comprising:
- particle sensing means having a sensing aperture through which said particles pass;
a vessel containing said liquid suspension;
a source of particle free liquid;
a small bore tube having one end immersed in said suspension and its other end juxtaposed with said aperture;
means for forcing said suspension at a predetermined pressure through said tube and toward said aperture, said tube acting as a fluid resistor having a pressure drop across it such pressure drop being a significant fraction of said predetermined pressure; and
hydrodynamic focusing means for directing a first flow of said particle free liquid through said aperture in cooperation with said liquid suspension said first flow being provided at substantially a pressure equal to said predetermined pressure minus said pressure drop.
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Abstract
Apparatus and a method therefor for counting platelets and red blood cells in a whole blood sample includes an aperture type transducer having front sheath and back sheath flows but also including various fluid resistors to maintan proper pressure differentials and which are driven from a common air supply. The whole blood sample is injected through the aperture by use of a small bore tube also driven by the common air supply.
49 Citations
34 Claims
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1. Apparatus for counting particles in a liquid suspension comprising:
- particle sensing means having a sensing aperture through which said particles pass;
a vessel containing said liquid suspension;
a source of particle free liquid;
a small bore tube having one end immersed in said suspension and its other end juxtaposed with said aperture;
means for forcing said suspension at a predetermined pressure through said tube and toward said aperture, said tube acting as a fluid resistor having a pressure drop across it such pressure drop being a significant fraction of said predetermined pressure; and
hydrodynamic focusing means for directing a first flow of said particle free liquid through said aperture in cooperation with said liquid suspension said first flow being provided at substantially a pressure equal to said predetermined pressure minus said pressure drop. - View Dependent Claims (2, 6)
- particle sensing means having a sensing aperture through which said particles pass;
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3. Apparatus for counting particles in a liquid suspension comprising:
- particle sensing means having a sensing zone through which said particles pass;
a vessel containing said liquid suspension;
a source of particle free liquid;
a unitary small bore tube of uniform diameter having an end juxtaposed with said sensing zone;
means for forcing said suspension at a predetermined pressure through said tube and into said sensing zone said tube acting as a fluid resistor having a pressure drop across it such pressure drop being a significant fraction of said predetermined pressure and hydrodynamic focusing means for directing a first flow of said particle free liquid through said sensing zone in cooperation with said liquid suspension said first flow being provided at substantially a pressure equal to said predetermined pressure minus said pressure drop. - View Dependent Claims (4, 5)
- particle sensing means having a sensing zone through which said particles pass;
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7. Apparatus for counting particles in a liquid suspension comprising:
- particle sensing means having a sensing zone through which said particles pass;
a source of particle free liquid;
a small bore tube having one end immersed in said suspension and its other end juxtaposed with said sensing zone;
means for forcing said suspension at a predetermined pressure through said tube and into said sensing zone said tube acting as a fluid resistor having a pressure drop across it such pressure drop being a significant fraction of said predetermined pressure; and
hydrodynamic focusing means for directing a first flow of said particle free liquid through said sensing zone in cooperation with said liquid suspension and including a fluid resistor for providing a pressure drop equal to said above pressure drop.
- particle sensing means having a sensing zone through which said particles pass;
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8. Apparatus for counting particles in a liquid suspension comprising particle sensing means having an aperture, an outlet chamber for said liquid suspension having an opening juxtaposed with said aperture for receiving said suspension after passage through said aperture;
- means for passing said liquid suspension through said aperture and toward said opening;
a source of particle free liquid;
hydrodynamic focusing means for directing a first flow of said particle free liquid through said aperture in cooperation with said liquid suspension;
means for directing a second flow of said particle free liquid into said opening of said outlet chamber to prevent eddy currents near said aperture;
said means for passing said liquid suspension through said aperture including a small bore tube having one end immersed in said suspension which is contained in a vessel and its other end juxtaposed with said aperture and means for forcing said suspension at a predetermined pressure through said tube said small bore tube having a pressure drop which is a significant fraction of said predetermined pressure. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
- means for passing said liquid suspension through said aperture and toward said opening;
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29. Apparatus for counting particles in a liquid suspension comprising particle sensing means having an aperture;
- an outlet chamber having an opening juxtaposed with said aperture;
means for passing said liquid suspension through said aperture and toward said opening;
a source of particle free liquid;
hydrodynamic focusing means including a fluid chamber connected to said source of particle free liquid for directing a first flow of said particle free liquid through said aperture in cooperation with said liquid suspension;
means for directing a second flow of said particle free liquid into said opening of said outlet chamber;
a fluid resistor connecting said fluid chamber to said second flow directing means said fluid chamber providing substantially all of said fluid for such means. - View Dependent Claims (30, 31, 32, 33)
- an outlet chamber having an opening juxtaposed with said aperture;
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34. Apparatus for counting particles in a liquid suspension comprising:
- particle sensing means having a sensing zone through which said particles pass;
a closed vessel containing a liquid suspension;
a source of particle free liquid;
a small bore tube having one end immersed in said suspension and its other end juxtaposed with said zone;
means for injecting a fluid under a predetermined pressure into said vessel for forcing said suspension through said tube and toward said sensing zone said small bore tube having a pressure drop which is a significant fraction of said predetermined pressure, means for directing under pressure a flow of said particle free liquid through said zone in cooperation with said liquid suspension; and
means for allowing removal of said vessel from said apparatus to expose said one end of said tube to the ambient atmosphere where said pressure of said particle free liquid causes said liquid suspension to back flow through said tube.
- particle sensing means having a sensing zone through which said particles pass;
Specification