Abstract: An obstruction detection circuit for detecting an obstruction of a sample probe of an automated sample aspiration/dispensation device and a method for detecting such an obstruction. In one embodiment the obstruction detection circuit includes a pressure sensor measuring the pressure in a fluid conduit connecting a pump and the sample probe orifice. The pressure within the connecting fluid conduit is measured by the pressure sensor shortly after the start of the aspiration or dispensation of a fluid volume by the automated sample aspiration/dispensation device. The pressure within the connecting fluid conduit is again measured after the completion of the aspiration or dispensation, and if the pressure has not returned to a predetermined range within a predetermined amount of time, an error condition is reported.

Abstract: A solid state, multi-use electrochemical sensor having an electrically nonconductive substrate, a working electrode, and a semi-permeable membrane covering the working electrode. The working electrode includes an electrically conductive material adhered to a portion of the substrate. A first portion of the conductive material is covered with an electrically insulating dielectric coating, and a second portion of the conductive material is covered with an active layer. The active layer includes a catalytically active quantity of an enzyme carried by platinized carbon powder particles, which are distributed throughout the active layer. A sensor package for incorporating a sensor is provided.

Abstract: A family of solutions that can be used to calibrate one or more electrochemical sensors has been developed. These systems can be used to determine analytes in biological fluids, such as whole blood, serum, plasma and urine. Since these reagents require preservatives in order to make their shelf life and use life commercially feasible, a system of preservatives which exhibits unexpected synergy in antimicrobial capabilities has been identified. The preferred preservative system includes a mixture of 5-chloro-2-methyl-4-isothiazolin-3-one; 2-methyl-4-isothiazolin-3-one; and 1,3-bis-(hydroxymethyl)-5,5-dimethyl-2,4-imidazolidinedione.

Abstract: A method for the detection of an analyte in a fluid sample using liposomes encapsulating acridinium esters (lumisomes). Hydrophilic polysubstituted aryl acridinium esters are useful as chemiluminescent markers and can be encapsulated within liposome vesicles without significant leakage of the esters from the vesicles. The lumisomes can be coupled to molecules with biological activity, such as antigens, antibodies, and nucleic acids, and used in luminescent assays.

Abstract: A method and apparatus for determining a plurality of substances or constituents of a specimen sample includes the steps of placing a single specimen sample in a reaction vessel or test tube and adding at least two reagents to the reaction vessel to form a detectable product and then initiating a reaction within the vessel and provide an emission of light energy in a predetermined spectral range. The reaction vessel is disposed in a chamber of a housing and a plurality of detector assemblies are disposed about the housing with portions of the detector assemblies disposed through the housing and exposed to the reaction vessel. Each of the detector assemblies receives a portion of the light emission and feeds such portion to a detector.

Abstract: A novel non-competitive immunoassay technique has been developed which not only improves sensitivity, but also is convenient and less susceptible to interfering factors. It is compatible with existing instruments and is an assay that can be run in one test tube. The analyte is reacted with labeled specific binder, after which the mixture is reacted with (1) an insoluble material attached to an analyte derivative and (2) a solid phase carrying a binder. The solid phase is then separated, and the label attached to the solid phase is measured.

Abstract: A multi-tasking clinical laboratory work-flow system for test sample and reagent transfer to semi-automate various laboratory assays. The system includes a controller having a menu of protocols which provide format instructions to a robotic sample transfer device. The sample transfer device includes a work-flow surface (deck) having defined coordinates for mounting one or more test racks and one or more reaction mediums, and means for interacting a test sample with one or more reagent(s) or gel in a reaction medium.

Abstract: An electrochemical/gas analyzer providing a rugged contact system for removable sensors capable of withstanding inexpert sensor insertion or removal, providing protection for high impedance input electronics against electrostatic discharge (ESD) damage, and providing automatic connection to diagnostic circuitry upon sensor removal has been developed. The contact system includes a plurality of stamped contacts electrically connecting a diagnostic circuit, including a source of diagnostic signals and a ground path, to analyzer signal processing circuitry. Removal of a sensor from this system electrically connects the sensor signal processing electronics to the diagnostic circuit. Insertion of the sensor interrupts electrical connection between the diagnostic circuit and the stamped contact, which connects the sensor terminals to the signal processing circuitry.

Abstract: New methods are provided for the amplification of a midivariant DNA containing an inserted target specific nucleic acid sequence(s) to enable detection of the presence of a target nucleic acid sequence in a test sample. One method employs midivariant DNA as a template for the synthesis of RNA catalyzed by QB replicase. Two midivariant DNA/probe conjugates including a nonreplicable portion of midivariant DNA and a target specific nucleic acid sequence (probe) are described. An amplification method including the steps of hybridization and ligation of the midivariant DNA/probe conjugates followed by replication of the DNA template has enabled detection of less than 200 template molecules. In a modified amplification method one of the midivariant DNA/probe conjugates further includes a RNA polymerase promoter sequence to enable transcription of the midivariant DNA template into RNA. The sequential ligation-transcription-replication method enables the detection of a single template molecule.

Abstract: An electrochemical sensor having a substrate, conductive strips deposited on the substrate, and a layer insulating portions of the conductive strips except those portions which define a working electrode and at least one second electrode. A solid electrolyte contacting the electrodes is covered by a semipermeable membrane which may comprise an acrylonitrile butadiene copolymer or an acrylate-based copolymer. A sample chamber is defined by the membrane, a cover member, and a gasket therebetween, and has a volume of from about 1 to about 2 .mu.L. The gasket is formulated from the highly cross-linked polymerization product of epichlorohydrin. All sensor components are selected such that a sensor operable for at least 2 days under normal conditions is produced.

Abstract: An assay method incorporating at least two different chemiluminescent compounds for detection and/or quantitation of at least two substances in a test sample is described. The synthesis of chemiluminescent reagents or conjugates for use in such methods as well as kits incorporating such reagents are also disclosed. The assays have particular application in the field of clinical diagnostics.

Abstract: A control system for providing a drive signal to an ultrasonic transducer and for controlling the tip motion of the ultrasonic transducer wherein the transducer tip is disposed in a hemolyzing chamber. The control system includes a sensor for sensing the motion of the transducer tip and a feedback circuit coupled between the sensor and the transducer where the feedback circuit provides a feedback signal to control the motion of the transducer tip.

Abstract: A novel fluid sampling device has been developed. This device provides for sample entry to be handled automatically by the instrument, thus allowing the operator to be involved in other activities while the sampling process is underway. It also assures reproduceable sample size, automatically cleans the sampling device between samples, and reduces the risk of user injury. Furthermore, the sampling system allows for the use of any forseeable collection mechanism.

Abstract: The invention pertains to a method for generating the fluorescence of polyanionic fluorophores in low dielectric media with fluorescence activation produced by specific quaternary onium compounds. The method may be used for measuring an analyte and may be useful in sensor devices.

Abstract: A method for measuring hyaluronic acid in a biological sample which comprises (a) coating a solid support with hyaluronic acid; (b) incubating the sample with cartilage proteoglycan; (c) exposing the incubated sample to the coated solid support; (d) then exposing the coated solid support to a keratan sulfate-reactive antibody; (e) determining the amount of antibody linked to keratan sulfate; and (f) correlating the amount of antibody linked to the keratan sulfate to the amount of hyaluronic acid in the sample.