Beckman Coulter, Inc.

Coulter International Corp.

Marco Zuleta

William Weigong Li

Richard A Marquis

Rongchang Xin

Santiago Galvez

Elgardo Echevarria

Pablo Larrea

Tan Nguyen

Christopher J Falvai

Paul M Grippo

Apparatus and method for aspirating liquid from a container, e.g., a test tube or other vessel, includes apparatus for sensing that an aspiration probe tip is contacting the inside bottom wall of the container, whereby a maximum volume of liquid can be aspirated from the container. According to the invention, an encoder is mounted on the driven member of a motor (e.g., on a rotatably-driven drive shaft or a nut of a stepper or D.C. motor, or on a linearly-driven shaft of a linear actuator) used to rectilinearly advance the probe tip into the container. Such encoder produces a series of pulses indicating the speed and/or linear position of the probe tip. A motor controller responds to a predetermined change in pattern of pulses from the encoder indicating that movement of the probe tip has been resisted by the vessel bottom, whereby further movement of the driven member and of the probe connected thereto is arrested, and the probe tip remains in contact with the vessel bottom.

Method and apparatus for maximizing liquid aspiration from small vessels

A method and apparatus for sensing different levels of liquids in their respective containers in a liquid-consuming and/or producing instrument system. According to a preferred embodiment, an elongated liquid-sensing probe having axially spaced electrodes adapted to sense liquid at multiple levels is arranged in each container of liquid. A controller, e.g. a suitably programmed microprocessor, operates to selectively poll different pairs of electrodes carried by the probe to determine whether or not the polled electrode pairs are immersed in the contained liquid. Preferably, the polling circuit comprises an electronically-controlled resistor that serves to normalize the level-sensing output signal for liquids of different bulk resistivity.

Method and apparatus for detecting liquid levels in liquid-storage containers

Apparatus for precisely aspirating small volumes of liquid, e.g., a blood sample, contained in a vessel, e.g., a test tube or vial, includes a mechanism for sensing that the tip of an aspirating probe is contacting the bottom of the vessel during the aspiration process. Such a bottom-sensing mechanism is adapted to sense a predetermined forcible interaction between the probe tip and the vessel bottom. In a preferred embodiment, such forcible interaction is sensed by detecting movement of a movably mounted platform that supports the vessel during aspiration. In a second embodiment, the forcible interaction is sensed by detecting the back-emf in a motor winding used to advance the aspiration probe.

Apparatus for aspirating liquid from a vessel

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Miami, FL, United States of America

Marco Zuleta