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: 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: Apparatus for drying a succession of microscope slides having wet blood specimen smears on a first major surface, including a belt transport for moving slides along a longitudinal drying path with their wet surfaces facing in a common direction and means for directing low velocity, heated air flows toward the non-smeared, major slide surfaces. Air flow proximate the slides preferably is about 15.degree. C. above ambient and at a velocity of about 10 to 30 feet per minute for a drying period of about 75 to 135 seconds, per slide.

Abstract: A blood analyzer system is provided with improved slide making capability by coupling a blood analyzer apparatus to an automatic slidemaking apparatus by means of a clinically effective blood specimen transport assembly, which includes a blood conduit forming a curvilinear flow path that imparts a substantial angular velocity component to blood moving therein. The system enables a blood analyzer portion and a smear slide portion of a given sample to be aspirated with physical and temporal proximity.

Abstract: An apparatus for dislodging fragile particles, such as intact biological cells, retained by the separation matrix in a flow chamber of a magnetic separation system. The apparatus incorporates a piezoelectric transducer which is coupled to the matrix and an associated drive circuit. The system can operate in a capture phase, whereby fragile particles are selectively captured from a carrier fluid passing through the matrix, with those captured particles being magnetically held in place within the matrix. In the elutriation phase, an elutriation fluid is passed through the matrix and the drive circuit excites the piezoelectric transducer. In response to the excitation, the transducer establishes acoustic waves in the elutriation fluid passing through the matrix, vibrating the matrix itself. Depending upon the mechanical impedances within the flow chamber, the acoustic waves can be ultrasonic.

Abstract: A system for the magnetic separation of fragile particles, such as intact biological cells, from a fluid medium. The system includes at least one high-gradient magnetic separator having a flow chamber housing an interstitial separation matrix and associated magnetizing apparatus for coupling magnetic flux to the matrix. The matrix has interstices through which a carrier fluid carrying the cells-to-be-separated may be passed. The magnetizing apparatus includes opposing North and South poles and field-guiding pole pieces, external to the flow chamber. The flow chamber comprises a dual-position flux-coupler. The flux-coupler is operative in a first position in the capture phase and in a second position in an elutriation phase. In the capture phase, the flux-coupler is positioned to permit the magnetic flux from one magnetic pole to pass through the matrix to the other magnetic pole.

Abstract: An optical microscope system includes an optics system and a frame. A selectively controlled stage assembly is coupled to the frame by vacuum-retained air-bearings. An air vacuum chuck coupled to the stage selectively aligns and supports an object-bearing slide for viewing with the optics system.

Abstract: A portable, manually operable device for preparing a monolayer film of a biological fluid sample or the like on a slide for microscopic examination. Said device includes a base for retaining the slide thereon and a spreader manually movable linearly relative to the base and slide in a pass which spreads a sample of the fluid on the slide into such a monolayer. Preferably, the spreader is constructed to be disposable.

Abstract: A microscopy system for automatically locating and re-locating objects-of-interest in an image which has one or more objects against a background. Each of the objects-of-interest is characterized by a predetermined set of features. In a preferred form, the invention is specifically directed to an automated microscopy system which is adapted for automatically analyzing biological (e.g., blood or cervical) cells on microscope slides. In other forms of the invention, differing types of objects may be identified as being objects-of-interest during a first automated pass and then re-located during a second pass for further analysis.

Abstract: Disclosed is a new method for magnetic separation from a carrier fluid of biological cells or other organic or inorganic particles having a negative surface charge. A paramagnetic salt is mixed with an aqueous solution of a chelating agent, for example EDTA. The cells or particles to be separated are mixed with this paramagnetic carrier solution, and the resulting mixture is exposed to a high gradient magnetic field. The cells or particles attract the chelated paramagnetic cations preferentially to the carrier solution such that the particles develop a magnetic susceptibility greater than that of the carrier liquid. The method achieves highly repeatable separations at lower magnetization fields than existing high gradient magnetic separation methods. Feasibility has been shown for erbium chloride and dysprosium chloride, with whole blood as the sample.

Abstract: An air vacuum chuck for a microscope includes a body member having a planar slide-supporting surface. Stop members are adapted to align a slide in a predetermined orientation. Air ports and vacuum ports in the slide-supporting surface selectively couple a relatively high pressure air reservoir and a vacuum reservoir, respectively, to the region between the slide-supporting surface and the object-bearing surface of the slide. The air ports are adapted to provide airflow directed towards at least one of the stop members. In an alignment mode, airflow from the air ports and vacuum from the vacuum ports establish a vacuum-retained air-bearing with a substantially frictionless coupling between a slide and the slide supporting surface. The vacuum from the vacuum ports controls the separation between the slide and the slide-supporting surface. The directed airflow imparts a net force on the slide, positioning the slide against the stop members.

Abstract: A portable, manually operable device for preparing a monolayer film of a biological fluid sample or the like on a slide for microscopic examination. Said device includes a base for retaining the slide thereon and a spreader manually movable linearly relative to the base and slide in a pass which spreads a sample of the fluid on the slide into such a monolayer. Preferably, the spreader is constructed to be disposable.

Abstract: A particle analyzer wherein a flow of liquid suspension, having individually entrained particles, flows along a predetermined path; a center pair of electrodes are positioned on opposed sides of the predetermined path: the center electrodes are energized to provide an electrical sensing field therebetween, two pairs of outer electrodes are positioned so that one pair is on each side of the center electrodes; the outer electrodes are oriented and/or energized so that their electrical fields bulge outward in the direction of the sensing field of the center plates to narrow the width of the sensing field along the predetermined path. Additionally, the field between the center plates can be focused in additional directions and the sensing electrode arrangement can be implemented in a flow cell, with or without an aperture, or on the surface of a substrate.