Altex Scientific, Inc.

Rainin Instrument Co., Inc.

Haakon T Magnussen, Jr

Stephen J Ruskewicz

Roy P Moeller

Kenneth Rainin

Gary L Smith

Anthony K Wingo

Scott N MacDonald

Alan C Berick

Ludovic S Filgas, Jr

A fluid pump for use in high performance liquid chromatography having a piston movable in a chamber for drawing fluid into, pressurizing, and delivering the pressurized fluid from the chamber. A pressure transducer in the chamber derives a pressure output signal indicative of chamber pressure. Means is provided for correcting offset errors in the pressure output signal.

Pressure measurement in fluid pump systems

A dashpot piston mounted in a closed chamber is coupled by an axially movable shaft to a pipette piston to regulate return movement of the pipette piston within a pipette cylinder to draw fluid into the cylinder. The dashpot shaft is movable within limits relative to the dashpot piston to accommodate a blow-out of residual fluid from the pipette by the shaft driving the pipette piston beyond a home position to blow residual fluid from the pipette cylinder. An air inlet port in the bottom of the chamber allows air to be drawn into the chamber with upward movement of the dashpot piston while a valve adjacent to the air inlet port opens in response to downward movement of the dashpot piston to exit air from the chamber. Control of the relative sizes of the air inlet port and valve outlet regulates the relative rates of upward and downward piston movement in the cylinder. The dashpot piston carries a movable plate of a variable capacitor transducer for monitoring the position of the pipette piston within the pipette cylinder.

Pipette mechanism

A hand held self-contained automated pipette for portable operation having an electrically operated digital linear actuator. The actuator preferably includes a stepper motor driving a rotor. A threaded screw is coaxially positioned within the rotor and is connected to an actuator shaft having elongate grooves slidable in a guide for preventing shaft rotation so that precise linear motion is imparted to the shaft. A pipetting displacement assembly having one of various sizes is removably attached for actuation by a common actuator including programmed movement of a displacing piston in a displacement cylinder to optimize air interface volume, neutralize variations in vacuum pipette effects, and provide an accommodated stroke and readout for improved accuracy while pipetting and/or titrating different ranges of volumes. A control circuit is provided so that the back EMF of the stepper motor coils is recirculated when power is duty-cycled off for power conservation. Conversely, recirculation is switched off when power is duty-cycled on for minimizing losses. Recirculation is switched off when coils are commutated which produces a rapid magnetic field collapse for assuring high torque. Upon calibration the piston undertakes immediate excursion to an end of travel limit and after motor slippage is retracted to a home position. This home position is chosen for optimum preservation of an air interface volume between drawn liquid and the piston tailored with particularity to the displacement assembly being used. Multiple precision modes including pipetting, multiple dispensing, titration, and dilution, are provided. Other features are also disclosed.

Methods and apparatus for pipetting and/or titrating liquids using a

A pipette is disclosed which includes a pipette body, a tip locking mechanism, and a disposable pipette tip. The pipette body has a plunger which reciprocates into and out of an interior air filled chamber. This air forces a measured amount of liquid into or out of the tip. After pipetting, an over-stroke of the plunger discharges a blast of air to assure discharge of all the fluid. In one embodiment, a further over-stroke unlocks a mechanism holding the shell in place and actuates tip disposal and replacement. The shell surrounding the pipette body is depressed by the plunger shaft. Fingers formed from the lower end of the shell are pushed outward by cam action with the pipette body. As the fingers spread, the tip falls free. A replacement tip is then attached. The fingers also define a funnel which guides the replacement tip on to the point where it snaps into position. The spring biased shell and fingers apply a uniform force holding the tip against a gasket at the end of the pipette body, and the shell is again locked in place.

Replaceable tip assembly for pipette

A system for remotely controlling one or more instruments from a control terminal. Each instrument includes a stored menu of operations it can perform under control of the terminal and an accumulator for producing an index number which selects a particular operation from the menu. The terminal includes means for transmitting commands to direct the instrument to increment the index number and to transmit back to the terminal a textual description of the currently selected menu entry. The terminal further includes means for directing the instrument to perform the operation designated by the current menu entry.

Instrument control system

A pressure booster system for fluids using one or more injectors for delivering a relatively low pressure output flow of fluid. A fluid accumulator receives the output from one or more injectors. A detector reveals any fluid mass change in the accumulator in relation to a selected value of fluid mass. A relatively high pressure pump increases the pressure of the output flow from the accumulator in accordance with the change of fluid mass within the accumulator which results in high pressure metering.

Pressure booster system for fluids

A photometric flow cell for high pressure liquid chromatography having an illuminated passageway therein between open ends of which fluid samples are flowed for analysis. An annular, porous flow impedance element is supported in an annular channel surrounding one end of the passageway. The impedance element reduces turbulence of flow through the open end by evenly distributing the flowing fluid circumferentially about the end opening.

Photometric flow cell

Circuit for starting and operating a gas discharge lamp. The circuit includes a resonant circuit having a high Q during both starting and operating conditions of the lamp, thereby permitting a high lamp operating voltage to be obtained from a relatively low voltage power supply. The circuit comprises a power supply, an inductor-capacitor series-resonant circuit connected across the power supply terminals, and a lamp circuit connected in parallel with the capacitor of the series-resonant circuit, wherein the lamp circuit comprises a second capacitor connected in series with a gas discharge lamp.

Discharge lamp ballast

A spectrophotometer utilizing a multiple wavelength electromagnetic wave source which is intercepted and dispersed into a spectrum. The spectrophotometer includes a closed loop servo positioning mechanism for simultaneously directing selected portions of the electromagnetic spectrum to a detector which analyzes these portions of the spectrum for analytical purposes.

Spectrophotometer

A fluid pump mechanism for delivering a smooth output of fluids to a system utilizing at least one piston in a chamber reciprocative therewithin. The piston has strokes that fill and empty the chamber in conjunction with the action of valve means located at the inlet and outlet of the chamber. Motive means causes reciprocation of the piston within the chamber. Control means is also included for minimizing the time during the piston cycle in which the piston is not emptying the chamber. The invention's scope also encompasses a pressure metering device for a fluid forcing means motivated by an electrical motor.

Growing community of inventors

Pinole, CA, United States of America

Haakon T Magnussen, Jr