Abstract: A liquid heater assembly including a heater body having therein a coiled tube for passing liquids, a pair of heating elements, a thermistor, a thermostat, and a backup thermostat. Liquid enters the coiled liquid tube at an inlet end and exits the coiled liquid tube at an outlet end. The coiled liquid tube is positioned within the heater body between the pair of heating elements. The outlet end extends below a planar surface of the heater body. The thermistor detects the temperature changes of the heater body. The resistance of the thermistor is used to regulate the supply of power to the heating elements. The thermostat and the backup thermostat are connected in series between the power source and the heating elements to provide a safety shutoff when the heater body reaches a predetermined overheat temperature. The heater body is maintained at a predetermined temperature by regulating the electrical current to the heating elements.

Abstract: A reaction vessel having a platform and a plurality of wells extending below the platform from openings in the platform. A support skirt extending below the platform by an opening therein, secures a cuvette to the reaction vessel. At the rear of the reaction vessel, a reaction vessel tab is disposed below the reaction vessel for facilitating transport of the reaction vessel through the automated analytical system.

Abstract: The present invention is a method for opening and closing a cap pivotally mounted on a container for storing reagents for use in an automated analytical instrument. The cap has one end for sealing the container and a tab extending from the other end for pivoting the cap. The method comprises the steps of positioning a closed container adjacent an actuating device mounted on the analytical system. The method further comprises the steps of projecting the actuating device against the top of the tab to pivotally open the cap to a position sufficiently vertical for aspirating reagent from the container, and retracting the actuating device from the cap to a position above the pivotal mounting thereof. The method comprises the final step of causing relative motion between the cap and the actuating device so that the actuating device drags along the top of the cap pivotally closing the cap to provide a sufficient seal on the container preventing evaporation of the reagent therefrom.

Abstract: A bubble flushing syringe for aspirating and dispensing fluids through an open-ended tip with precision and volumetric accuracy is disclosed. The syringe comprises a piston within a bore formed by a generally cylindrical wall having a closed end and an open end, wherein the piston forms an annulus with the wall and closed end of the bore, and is capable of reciprocating therein. The syringe further comprises an annular seal seated in the open end of the bore and circumventing the piston to close the annulus sufficiently snug to retain fluid when the piston reciprocates therethrough. An inlet for directing fluid to the annulus through the wall of the bore and an outlet for directing fluid from the annulus through the wall of the bore to the open-ended tip are positioned proximal to the annular seal and the line generally axially therebetween. A drive device is connected to the piston for reciprocating the piston within the bore.

Abstract: An automated, continuous and random access analytical system, having apparatus and methodology capable of simultaneously performing multiple assays of liquid samples using different assay methodologies, and providing continuous and random access while performing a plurality of different assays on the same or different samples during the same time period, is disclosed. A method is also disclosed of operating an automated continuous and random access analytical system capable of simultaneously effecting multiple assays of a plurality of liquid samples wherein scheduling of various assays of the plurality of liquid samples is followed by creating a unit dose disposable and separately transferring a first liquid sample and reagents to a reaction vessel without initiation of an assay reaction sequence, followed by physical transfer of the unit dose disposable to a processing workstation, whereby a mixture of the unit dose disposable reagents and sample are achieved during incubation.

Abstract: A method for modifiying a liquid assay reagent to provide prolonged homogeneity thereof, particularly where the liquid assay reagent comprises microparticles for performing a heterogeneous immunoassay, is provided wherein the addition of an inert material to a liquid assay reagent achieves neutral density to thereby prolong the homogeneity thereof for extended periods of time. A method for the automated agitation of assay reagents to maintain the homogeneity thereof with an automated, continuous and random access analytical instrument is also provided. The automated mixing is accomplished by a back and forth motion of a carousel onto which assay reagent containers or packs are mounted with asymmetric pauses which can be completed within a short period of time. The carousel acceleration, velocity, distance moved, and pause-asymmetry are optimized to provide rapid assay reagent resuspension without foaming or bubble formation.

Abstract: A plastic assay cuvette having the desired optical properties for the analysis of a test sample or reaction mixture thereof, and a method for making such plastic assay cuvette, are described. The optical properties of the plastic assay cuvette are substantially the same as the optical properties of glass wherein low birefringence throughout the optical read region thereof is provided. When used for the analysis of a test sample or reaction mixture thereof, such as in fluorescence polarization assays and absorbance assays, the plastic assay cuvette provides accurate and reproducible results while, at the same time, provides a low-cost disposable assay cuvette which can be used in place of conventional glass assay cuvettes.

Abstract: An automated, continuous and random access analytical system, having apparatus and methodology capable of simultaneously performing multiple assays of liquid samples using different assay methodologies, and providing continuous and random access while performing a plurality of different assays on the same or different samples during the same time period, is disclosed. A method is also disclosed of operating an automated continuous and random access analytical system capable of simultaneously effecting multiple assays of a plurality of liquid samples wherein scheduling of various assays of the plurality of liquid samples is followed by creating a unit dose disposable and separately transferring a first liquid sample and reagents to a reaction vessel without initiation of an assay reaction sequence, followed by physical transfer of the unit dose disposable to a processing workstation, whereby a mixture of the unit dose disposable reagents and sample are achieved during incubation.

Abstract: Apparatus for measuring electrolyute concentrations in fluid samples. The apparatus includes an ion selective electrode having a plurality of ion selective detection sites. Each site has an affinity for a preselected electrolyte of interest and generates a potential having a magnitude related to the concentration of the corresponding electrolyte in the sample. A voltage to optical transducer circuit is provided to convert the voltage differentials to optical signals having intensity related to the concentration of the electrolytes in a first embodiment, a digital code related to the concentration of the electrolytes in a second embodiment, and an optical absorption or density value related to the concentration of the electrolytes in a third embodiment. The optical signals are suitable for detection by conventional optical detector apparatus of assay instruments and may be processed using conventional two point linear interpolation techniques to determine the concentrations of the preselected electrolytes.

Abstract: An ink jet printer for depositing drops of ink at a plurality of print positions on a moving print receiving medium includes a print head producing at least one jet drop stream directed toward the medium and a charge electrode positioned adjacent the point of drop formation of the jet drop stream. A charging means repetitively applies a high guard drop potential to the charge electrode during formation of at least every second drop for charging of the drops to a guard charge level. During formation of the remainder of the drops, either one of a number of relatively low print potentials or a substantially larger catch potential is applied to the charge electrode. Drops formed during application of a print potential to the electrode may carry a charge of either electrical polarity due the drop-to-drop cross talk from previously formed guard drops.

Abstract: An ink drop duplicating system employs a plurality of angularly extending ink drop print heads to reproduce an original document. Each printing head produces a row of drop streams which are individually controlled to deposit printing drops at a plurality of printing positions along a line extending perpendicular to the major axis of the printing head. Printing control information for the ink drop printing heads is generated by a photosensing array which extends across one major dimension of an original document and which is scanned across the other major dimension. Scanning data is stored on a magnetic disk. After one or more original documents have been completely scanned, the scanning data is read from the magnetic disk and reorganized to produce drop control signals for the ink drop printing heads.

Abstract: A print system for duplex printing a plurality of document page images on a plurality of copy sheets includes means for storing print control information which defines the document images. An ink jet printer prints the page images on copy sheets as they are transported past a print station by a transport arrangement defining a closed sheet path. The sheet path is of sufficient length such that a number of copy sheets are transported simultaneously therethrough. A copy sheet inverter receives copy sheets sequentially from the sheet path after the sheets are printed on their first sides and returns them to the sheet path in an inverted orientation prior to printing on the second sides of the copy sheets.

Abstract: An ink drop printing system for use as part of a duplicator. Sheets which are to be printed by the printing system are fed from one or another of two separate paper supplies and delivered along downwardly converging delivery paths toward a common reception point on a printing transport. The printing transport carries the sheets along a printing path which is angled upwardly and folded back from the delivery paths toward the common reception point. While the sheets are carried upwardly by the printing transport, they are printed by a plurality of inclined, angularly extending, and cooperatively operated jet drop printing heads.

Abstract: An ink jet fluid system and process of startup and shutdown is provided which includes a print head having a fluid manifold and at least one orifice for forming a jet drop printing stream. Inlet and outlet valves are connected to inlet and outlet openings of the print head. During shutdown, fluid is continuously circulated around the print head through a bypass line while the outlet of the print head is connected to a source of reduced pressure to prevent fluid from flowing through the orifice. At startup, the inlet and outlet valves are actuated to provide a continuous flow of fluid under pressure to the print head. In another embodiment of the invention, a fluid system is provided for a multiple print head device and provides for independent control of the fluid pressure in each print head.