Abstract: Separation apparatus and method for separating magnetic and/or magnetically-labeled particles from a test medium. Test medium within a reaction chamber is caused to flow past a collecting surface, and a high-gradient magnetic field is applied to the surface to capture magnetically responsive particles in the test medium. The particles are deflected toward the collection surface by baffles, a spinner, or a sprayer, or are funneled past the surface by a plunger operable to be displaced into close proximity to the surface to provide a narrow flow path for the particle-laden test medium. The particles normally suspended in the medium are separated out of suspension by adhesion to the collection surface. The particles may be resuspended by removal of the surface from the high-gradient field, or removal of the high-gradient field from the surface. The collection surface is a thin-walled non-magnetic material having a plurality of magnetic pole faces positioned therearound.

Abstract: Separation apparatus and method for separating magnetic and/or magnetically-labeled particles from a test medium.

Abstract: Separation apparatus and method for separating magnetic and/or magnetically-labeled particles from a test medium in a reaction chamber which incorporates baffles, a spinner, a stirrer, or a plunger operable to be displaced along a collection surface to define a narrow flow path through which the particle-laden test medium must flow. The collection surface is a thin-walled non-magnetic material having a plurality of magnetic pole faces positioned therearound. Test medium within a reaction chamber is caused to flow past a collecting surface, and a high-gradient magnetic field is applied to the surface to capture magnetically responsive particles in the test medium. The particles are deflected toward the collection surface in the flow path for the test medium. The narrow flow path assures that substantially all of the particles pass within the high-gradient magnetic field along the collection surface.

Abstract: An apparatus for observation of magnetically labeled cells comprises an arrangement of magnets that are configured in confrontation across a horizontal gap. The magnets are further configured to produce a substantially uniform vertically-directed gradient in the gap. A sample vessel containing a fluid sample is positioned in the gap in order to allow the vertical gradient to cause collection of magnetically-labeled species on the interior upper surface of the vessel. The vessel is preferably transparent to allow observation of the collected species.

Abstract: The present invention relates to apparatus and methods for separating, immobilizing, and quantifying biological substances from within a fluid medium. Biological substances are observed by employing a high internal gradient magnetic capture structure formed within a vessel, in conjunction with an externally-applied force for transporting magnetically responsive material toward the capture structure. The invention is also useful in conducting quantitative analysis and sample preparation in conjunction with automated cell enumeration techniques.

Abstract: A buried-heterostructure distributed feedback laser is described, including a grating structure at a surface of a nonplanar cladding layer. The grating structure can be made by transfer of a pattern by ion milling, the pattern being defined in an ion-beam resist layer, e.g., by direct-writing electron-beam exposure. Low-threshold, high-power lasers are obtained with a commercially favorable yield.