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  Automated pipette machineUSPTO Application #: 20070180935Title: Automated pipette machine Abstract: A pipette nozzle is provided for use on a movable arm on an automated pipette machine. The pipette nozzle includes a body defining a passage therethrough. At least two seating surfaces are provided on the body, including a first seating surface and a second seating surface. The first seating surface is configured to receive and sealingly mate with a first size of pipette tip in a manner such that the first end of the passage is in fluid communication with the first size of pipette tip. The second seating surface is configured to receive and sealingly mate with a second size of pipette tip in a manner such that the first end of the passage is in fluid communication with the second size of pipette tip. There is also provided an automated pipette machine which includes a tip ejector system including an arm that is movable between a first position and a second position, wherein in the first position the arm is positioned to engage the tip during movement of the nozzle along a selected path and to prevent movement of the tip along the selected path while permitting the nozzle to move along the selected path, so that the movement of the nozzle along the selected path causes the nozzle and the tip to disengage from each other, and wherein in the second position the arm is positioned to avoid engagement with the tip during movement of the nozzle. There is also provided an apparatus for use on an automated pipette machine for transmitting pressure changes produced by a pump on the machine to a pipette nozzle. The apparatus comprises a housing defining a chamber a first conduit and a second conduit. The first conduit extends into the chamber and has a first opening positioned in the chamber. The first conduit is fluidically connectible to the nozzle. The second conduit extends into the chamber and has a first opening positioned in the chamber. The second conduit is fluidically connectible to the pump. The first opening of the first conduit is positioned above the first opening of the second conduit. The chamber defines at least a selected volume between the height of the first opening of the first conduit and the height of the first opening of the second conduit. (end of abstract) Agent: Kramer & Amado, P.C. - Alexandria, VA, US Inventors: Andrew Angus, Fred Davis, Adam Donath, Richard Grant, Dirk Kurpershoek USPTO Applicaton #: 20070180935 - Class: 073864140 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070180935. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] This invention relates generally to automated apparatus for handling chemical and biological fluids, and more particularly to automatic pipette machines. BACKGROUND OF THE INVENTION [0002] Automatic pipette machines or robots are used in the chemical and biological fields to automatically pipette fluids from one place to another, without the need for direct human involvement. Generally, automated pipette robots have three axes of motion to allow a moveable tip head to access different containers with fluid samples in a given area. One class of robots are known as .theta.-z-.theta. robots which combine rotational (.theta.) and vertical (z) motion of a robot arm holding the tip head with rotational (.theta.) motion of a carousel that holds the samples, thereby allowing the tip head to access the samples on the carousel. A more common class of robots are x-y-z gantry style robots (e.g. BioMek FX.TM., Qiagen.TM. Biorobots.TM.) where the moveable tip head moves along one vertical axis and two orthogonal horizontal axes of motion. To avoid contamination, many automatic pipette machines use disposable pipette tips. Typically, the tip head on these robots has one or more nozzles that receive a pipette tip. [0003] Typically, the tip heads on the automated pipette robots can accommodate only one size of disposable pipette tip. However, a given size of pipette tip is best suited for pipetting a limited range of volumes of fluid. Some processes require that a wider range of volumes of fluid be transferred from one place to another than can be accommodated by the tip. In such instances, either the pipette head must make multiple trips between the source and destination locations in order to cumulatively transfer the required volume, or human intervention is required to transfer the volumes that cannot be effectively handled by the pipette machine. It would be desirable to provide an automated pipette machine capable of pipetting a wider range of volumes. [0004] Automated pipette systems often use a hydraulic fluid in the fluid lines that connect the pump to the pipette tip head because hydraulic fluids are less compressible than air. As the liquid volume in the pipette tip increases, the pressure drop between the pump and the tip head increases. It is easier to calibrate the pump to attain the desired pipette volume accuracy if most of the volume in the line between the pump and the tip head is a hydraulic fluid. In addition, for positive displacement pumps, the volume of liquid the pump can draw into the tip with a single piston stroke is higher using a hydraulic fluid. [0005] Existing automated pipette technology is limited to aspirating a maximum of approximately 1 mL of liquid. In these machines, there is tubing of a relatively small diameter and of sufficient length between the tip head and the pump to accommodate up to 1 mL of air displaced from the pipette tip during aspiration. Small diameter tubing is used so that if there is an interface between hydraulic fluid and air in a section of the tubing that is not horizontal, the hydraulic fluid does not flow down into the air volume. If this occurs, then air can be inadvertently introduced into the pump, causing a loss of volumetric dispensing accuracy. Many analysis processes require that volumes significantly greater than 1 mL be pipetted. To pipette larger volumes of fluid a longer tube can be used while maintaining the diameter of the tube constant so that the tube remains small enough in cross-section so that no air is inadvertently introduced into the pump during operation. [0006] A longer tube, however, has several drawbacks associated with it. For example, in a long length of tubing there is an increased chance that as the hydraulic fluid is drawn into the pump, there will be breaks at the air-hydraulic fluid interface resulting in the formation of discrete bubbles between the main interface and the nozzle. When the pump initiates the dispensing step, these bubbles will be ahead of the main interface and may be expelled from the nozzle, contaminating the tip and potentially contaminating the fluid that the tip aspirated, and the fluid volume into which the tip is dispensing. Additionally, a long length of tubing provides increased pressure drop at a given fluid flow-rate, which in turn, means that pump cavitation would occur at a relatively lower flow-rate during aspiration. Furthermore, the increased pressure drop reduces the maximum dispensing flow-rate. Another drawback is that, for both the aspirating and dispensing steps, the higher pressure drop through a long length of tubing may increase the chance of leakage at connections between the different tubes, the pump, and the nozzle, since higher (or lower) initial pressures are required at the pump to achieve operation. [0007] These drawbacks associated with longer tubing as described above also apply to the use of small diameter tubing for 1 ml machines that are currently in use. In other words, for any machine that incorporates a length of relatively small diameter tubing which functions as a reservoir for air during operation, the above described problems are present. [0008] It would be desirable to have a system that can transfer volumes of fluid without incorporating long hydraulic fluid lines. [0009] Another drawback related to current automated pipette machines relates to the disposal of used pipette tips. There are currently various mechanisms proposed and in use for removing disposable pipette tips from the pipette nozzle. However, many of these mechanisms are relatively intricate, thereby increasing the complexity of the pipette machines and the cost of manufacture. Furthermore, many of the devices of the prior art eject the pipette tip in an uncontrolled manner, usually into a disposal bin, thereby making it impractical to reuse the tip if desired. For example, in some analysis techniques, the same material is transferred in non-consecutive steps, in which case reuse of the tip is desirable since contamination is not an issue. It would be desirable to have a pipette machine that is capable of reusing a pipette tip. SUMMARY OF THE INVENTION [0010] In a first aspect, the invention is directed to a pipette nozzle for use on a movable arm on an automated pipette machine. The pipette nozzle includes a body defining a passage therethrough. The pipette nozzle includes a connecting portion on the body for connecting the pipette nozzle to the movable arm. There are provided at least two seating surfaces on the body, including a first seating surface and a second seating surface. The first seating surface is configured to receive and sealingly mate with a first size of pipette tip in a manner such that the passage is in fluid communication with the first size of pipette tip. The second seating surface is configured to receive and sealingly mate with a second size of pipette tip in a manner such that the passage is in fluid communication with the second size of pipette tip. [0011] In a second aspect, the invention is directed to an apparatus for use on an automated pipette machine for transmitting pressure changes produced by a pump on the machine to a pipette nozzle. The apparatus includes a housing defining a chamber. The apparatus further includes a first conduit extending into the chamber and having a first opening positioned in the chamber. The first conduit is fluidically connectible to the nozzle. The apparatus further includes a second conduit extending into the chamber and having a first opening positioned in the chamber, wherein the second conduit is fluidically connectible to the pump. The first opening of the first conduit is positioned above the first opening of the second conduit. The chamber defines at least a selected volume between the height of the first opening of the first conduit and the height of the first opening of the second conduit. [0012] In a third aspect, the invention is directed to a tip ejector system for use on an automated pipette machine to eject a pipette tip from a pipette nozzle on the machine. The tip ejector system includes an arm that is movable between a first position and a second position. In the first position the arm is positioned to engage the tip during movement of the nozzle along a selected path thereby preventing movement of the tip along the selected path while permitting the nozzle to move along the selected path, so that the movement of the nozzle along the selected path causes the nozzle and the tip to disengage from each other. In the second position the arm is positioned to avoid engagement with the tip during movement of the nozzle. [0013] In a fourth aspect, the invention is directed to an automated pipette machine including a movable carousel having a plurality of pipette receptacles, a movable pipette machine arm with a pipette nozzle attached thereto, and a tip ejector system. The pipette nozzle includes a body defining a passage therethrough and at least two seating surfaces on the body, including a first seating surface and a second seating surface. The first seating surface is configured to receive and sealingly mate with a first size of pipette tip in a manner such that the passage is in fluid communication with the first size of pipette tip. The second seating surface is configured to receive and sealingly mate with a second size of pipette tip in a manner such that the passage is in fluid communication with the second size of pipette tip. The tip ejector system includes a tip ejector arm that is movable between a first position and a second position, wherein in the first position the tip ejector arm is positioned to engage the tip during movement of the nozzle along a selected path and to prevent movement of the tip along the selected path while permitting the nozzle to move along the selected path, so that the movement of the nozzle along the selected path causes the nozzle and the tip to disengage from each other, and wherein in the second position the tip ejector arm is positioned to avoid engagement with the tip during movement of the nozzle. BRIEF DESCRIPTION OF THE DRAWINGS [0014] For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made by way of example to the accompanying drawings, in which: [0015] FIG. 1 is perspective view of an automated pipette machine in accordance with an embodiment of the present invention; [0016] FIG. 2 is a side view of a pipette arm of the machine in FIG. 1; [0017] FIG. 3 is a side view of a nozzle of the pipette arm in FIG. 2; [0018] FIG. 4 is a cross-sectional view along section line 4-4 shown in FIG. 3; [0019] FIG. 5 is a side view of the nozzle shown in FIG. 1, with a first pipette tip mounted thereon; [0020] FIG. 6 is a side view of the nozzle shown in FIG. 1, with a second pipette tip mounted thereon; Continue reading... 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