Abstract: An apparatus is provided for quantitatively measuring combinations of magnetic particles combined with analytes whose amount or other characteristic quality is to be determined. The magnetic particles are complexed with the analytes to be determined and are excited in a magnetic field. The magnetizations of the magnetic particles are thereby caused to oscillate at the excitation frequency in the manner of a dipole to create their own fields. These fields are inductively coupled to at least one sensor such as sensing coils fabricated in a gradiometer configuration. The output signals from the sensing coils are appropriately amplified and processed to provide useful output indications.

Abstract: An apparatus for analyzing particles suspended in a fluid. The fluid has electrical properties different from that of the particles. The fluid and particles move from a first fluid containing portion to a second fluid containing portion through a conduit or aperture. A first pair of electrodes, each electrode of the pair being in a respective fluid containing portion. A constricted electrical path is defined between the first and second electrodes, and the path extends along the aperture. At least one other pair of electrodes is positioned in a non-encircling arrangement, and are aligned with each other and transversed to the constricted electrical path. This configuration eliminates many common errors suseptible to other devices.

Abstract: In this invention, a cell parameter, for example cell volume, is determined by subjecting one or more aliquots of a sample cell suspension to one or more alterations of at least one parameter of the cell environment to identify a point at which the cells achieve a particular shape to obtain a sample specific shape compensation factor. Preferably, the environmental parameter change is a reduction in osmolality.

Abstract: Apparatus for determining the size of a particle or cell within a fluid, includes a sample chamber for the fluid, a flow restrictor including an orifice, a pair of electrodes disposed on opposite sides of the orifice and signal measurer for measuring a signal representative of the impedance variation between the electrodes thereby to determine the size of a particle within the fluid passing through the orifice, and further including blockage detector for detecting blockage of the orifice, whether partial or complete.

Abstract: A flow cell for a particle analyzer using an electrical sensing zone method, includes: a detecting member having a through hole; a first cell for supplying a particle containing liquid to the through hole; a second cell for receiving and discharging the particle containing liquid that has passed through the through hole; electrodes provided in the first cell and the second cell respectively, for supplying an electrical current to the liquid passing through the through hole; and a sliding member for sliding at least one of the first and second cells to change a distance therebetween; wherein the first and second cells cooperate with the sliding member to detachably sandwich the detecting member therebetween so that the detecting member is connected to the first and second cells in a watertight state.

Abstract: The subject of the invention is a method for minimizing Coulombic losses in impactors and an impactor, in which Coulombic losses have been minimized. The method according to the invention is based on restricting the force effect of the charges accumulated in impactor's insulators on the charged particles. This restriction of the force effect can be realized, for example, by placing an electrically conductive surface between the insulator and the flow, or by forming an insulator so that the force effect is minimized.

Abstract: A probe for insertion into molten metal to detect and measure particulates suspended therein includes an inner tube of an electrically insulated material forming a metal receiving chamber, the tube having an orifice to permit molten metal to flow into the chamber. A first electrode extends into the chamber for engaging metal within the chamber and a second electrode surrounds at least a portion of the inner tube for engaging molten metal outside of the chamber. The electrodes may be connected to a measurement device for establishing a current path through the electrodes and passing through the orifice for measuring changes in the electrical potential produced by the passage of particulates entrained in the molten metal passing through the orifice.

Abstract: An apparatus for determining the size of a particle or cell within a fluid includes a sample chamber for the fluid, a flow restrictor having an orifice, a pair of electrodes disposed on opposite sides of the orifice and a signal measurer for measuring a signal representative of the impedance variation between the electrodes thereby to determine the size of a particle within the fluid passing through the orifice, and further includes a blockage detector for detecting blockage of the orifice, whether partial or complete.

Abstract: Apparatus and method for providing a classification of inclusions in molten metal. The apparatus and method include the steps of and means for obtaining an analog signal stream from a data collection apparatus, passing the analog signal stream through an analog to digital converter to convert the analog signal stream to a digital signal stream, and partitioning the digital signal stream into a discrete time frame of 5 milliseconds. The digital signal stream is vector normalized to provide a normalized signal stream having a largest amplitude magnitude of 1. The normalized signal stream is compared to a control of a prototype shape for determining a classification for the digital signal stream over the discrete time frame by decision logic to determine hard inclusions versus soft inclusions in the liquid metal.

Abstract: An orifice arrangement for sensing by the electrical resistance pulse method the volume of particles in a fluid suspension passing through an orifice which comprises an orifice member made of electrically insulating material (1) and electrically resistive material (2) disposed before, within, and after the orifice. The orifice is cylindrical with well rounded entry and exit corners. The resistive material has an aperture for the passage of particles through it and the orifice generally centered with the orifice center. The resistive material has an electrical resistivity matching that of the particle suspending fluid. Thus the electric field within the orifice is substantially the same with or without the resistive material. The aperture restricts particles to trajectories through the orifice where the maximum electric field intensity is substantially uniform thus accurately sizing the particles.

Abstract: First a liquid volume is comminuted into individual droplets in order to measure the volume of liquid droplets, then an electric potential different from that of the ambience is applied to the droplets, said potential determining the droplet charge as a function of its capacitance to its ambience. Finally, after charge to voltage conversion and measuring this capacitance-dependent value, the capacitance and the volume of such a drop can be determined. A liquid drop collecting vessel (2, 40) is provided for that purpose and comprises a droplet dripper (4, 42) to deliver individual droplets, further a device to charge the individual droplets formed by the drippers (4, 42). A measurement device (8, 44) is mounted underneath the liquid droplet collector vessel (2, 42) and is connected to a droplet collector electrode (16, 46) to determine the droplet capacitance by means of a voltage jump or a derivative test value.

Abstract: A junction field effect transistor (JFET) RF oscillator-detector circuit generates an RF signal for an apparatus for conducting electrical measurements of particles contained in a carrier fluid passing through an aperture in a cytometer flow cell. The JFET oscillator includes a plurality of parallel-coupled JFETs having respectively different VDS vs. IDS characteristics, that are biased to operate at square law detection regions of their respective VDS vs. IDS characteristics. One JFET operates in Class C mode, while the other operates in Class AB mode. An RF resonant circuit is electrically coupled to the JFETs and to the measurement cell, and is operative to establish the frequency of an RF field applied to the measurement cell. An RF load change detection circuit is coupled to the RF resonator circuit and is operative to detect an RF load change associated with a modification of the RF field as a result of a particle within the measurement cell aperture.

Abstract: Current density distributions of the ion beam in the scanning direction (the direction of X) at two points Zf and Zb on Z-coordinate are respectively measured by Faraday arrays. Using the thus measured current density distributions, a current density distribution in the scanning direction of the ion beam at an arbitrary position on Z-coordinate located in a workpiece is found by the method of interpolation. Using the thus found current density distribution, a waveform of scanning voltage V(t) of the ion beam is reformed so that a scanning speed of the ion beam can be relatively decreased at a position where the current density must be raised in the current density distribution and a scanning speed of the ion beam can be relatively increased at a position where the current density must be lowered. Due to the foregoing, a current density distribution in the scanning direction of the ion beam at an arbitrary position on Z-coordinate located in the workpiece is adjusted to a desired distribution.

Abstract: The invention provides molten metal inclusion sensor probes having a sensing passage through which the molten metal passes, while a direct current path is established through the passage between two electrodes. The passage of an inclusion through a central sensing zone within the passage changes the electric resistance in the current path, resulting in a detectable pulse indicating its size, and enabling the number of particles in a sample to be counted. Previously the passage has been cylindrical, with or without a conical entrance to facilitate smooth flow, or of randomly smoothed profile produced by heating the material at the passage mouth until it melts and flows. The flowing metal produces a self-induced magnetic field and electromagnetic force that results in a “conditioning” flow when the current is above a threshold value.

Abstract: An on-line somatic cell analyser and a method for evaluating the quantity of somatic cells present in a sample of milk are provided. A flow cell is connected to a milking hose and admits a constant volume of sampled milk into a flow chamber. A probe with two electrodes is positioned in a zone of optimal sensing inside the flow chamber and provides a modulated signal with an intensity value corresponding to the number of sodium ions present in the sample. A detection unit receives the modulated signal and generates a ion count signal whenever the number of sodium ions is above a reference value. A control unit converts the ion count signal into a somatic cell count (SCC) score. A step graph comprising a plurality of SCC thresholds defining a plurality of milk categories is stored in a memory and used by the control unit to classify the sample in a quality category according to the SCC score of the sample.

Abstract: Apparatus for quantitatively measuring groups of magnetic particles. The particles are complexed with substances to be determined and are excited in a magnetic field. The magnetic particles are thereby caused to oscillate at the excitation frequency in the manner of a dipole to create their own fields. These fields are inductively coupled to sensing coils fabricated in a gradiometer configuration. The output signals from the sensing coils are appropriately amplified and processed to provide useful output indications.

Abstract: Apparatus for sensing and characterizing particles suspended in a liquid medium includes a particle-sensing structure having a continuous wall defining a hydrodynamically smooth conduit through which the liquid suspension of particles is caused to pass simultaneously with an electrical current. Particles passing through the conduit are sensed and characterized by monitoring changes in the electrical current through the conduit. According to the invention, the continuous, conduit-defining wall is made entirely of a material having an electrical resistivity less than or equal to that of the liquid medium. Thus, the apparatus of the invention is similar to the conventional Coulter aperture (conduit) except that the aperture is formed from an electrically conductive material instead of a dielectric material.

Abstract: Apparatus and method are disclosed for providing a classification of inclusions in molten metal. The apparatus and method include the steps of and means for obtaining an analog signal stream from a data collection apparatus, passing the analog signal stream through an analog to digital converter to convert the analog signal stream to a digital signal stream, and partitioning the digital signal stream into a discrete time frame of 5 milliseconds. The digital signal stream is vector normalized to provide a normalized signal stream having a largest amplitude magnitude of 1. The normalized signal stream is compared to a control of a prototype shape for determining a classification for the digital signal stream over the discrete time frame by decision logic to determine hard inclusions versus soft inclusions in the liquid metal.

Abstract: A fluid contamination analyzer employs one or more micro-miniature sensors which provide for a substantial reduction in sensor dimensions form prior art dimensions of approximately 2 in.×2 in. to approximately 1 mm×1 mm. The sensors are incorporated into probes for easy lubricant fluid accessibility or alternatively may be employed in an on-line analyzer residing in the fluid flow path. The sensors sense an impedance of the fluid which is a function of its contamination and communicates the impedance to analysis circuitry via either a hard-wired or RF data link. An array of sensors may also be utilized in conjunction with a magnetic field intensity gradient to obtain a particulate distribution across the array. Impedance information, which is indicative of the particulate distribution, is communicated to analysis circuitry individually or in a multiplexed format for fluid contamination analysis.

Abstract: The present invention is a method of measuring the total volume of solids in a suspension, comprising the steps of: establishing a potential across a predetermined spatial volume; passing a portion of the suspension through the predetermined spatial volume; substantially continuously measuring the potential across the predetermined spatial volume over a first predetermined period of time; comparing the measured potential with a baseline; and calculating the total volume of solids in the suspension as a function of a total absolute deviation of the measured potential from the baseline. The baseline is preferably a dynamic baseline, and is determined with reference to the starting point of a sharp rise in the measured potential.

Abstract: A Coulter apparatus comprises a volumeter assembly containing a conduit through which a particle suspension is caused to pass simultaneously with an electrical current. In preferred embodiments the volumeter assembly comprises at least one traditional Coulter conduit wafer, i.e., a dielectric wafer containing a central circular conduit, and at least two electrically conductive collars. The conductive collars approximate the conduit diameter in thickness, are uninsulated, and are attached to opposite sides of the conduit wafer, the openings being congruent with the Coulter conduit. The Coulter conduit in the dielectric wafer and the openings in the conductive collars collectively form a hydrodynamically smooth conduit, in which the electric and hydrodynamic fields of the Coulter conduit are amended. The electric field is shaped to confine the particle-sensitive zone of the novel volumeter conduit within the conduit's physical boundaries, thereby decreasing the zone's coincidence volume.

Abstract: A micro-electric detector provides conductivity or impedance based measurements of a test sample placed in a microchannel of a micro-analysis system. The detector includes a pair of electrodes disposed on opposing sidewalls of the microchannel to create a detection zone in the microchannel between and adjacent to the electrodes. A variety of test samples can be monitored by the detector, such as particulate-containing fluids and biological materials including living cells and subcellular structures. The detector can be integrated on-chip using micromachining techniques with a variety of micro-analysis systems.