JPH08266913A - Pipette chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a barrier of a disposable pipette tip by which sufficient air flow is flown to an absorbing apparatus and sufficient catching of aerosol is continued by making the barrier of continuous bubble foam which prevents preventing aerosols from arriving at a base end part from an end of the passageway without limiting air flow passing through the passageway. SOLUTION: The pipette tip 10 has the base end part 20 and a terminal part 25, the base end part 20 is larger than the terminal part 25, and is provided with a canula 15 both end parts 20, 25 of which are connected by the passageway 50. The barrier 60 is provided in the passageway 50 of the pipette tip 10 near the base end part 20 of the canula 15, catches a liquid and the aerosol to prevent them from flowing out of the base end part 20 through the pipette tip 10 and further makes sufficient air flow through the passageway 50 of the pipette tip 10 to permit an air flow liquid detecting system in an automated aspirating instrument to properly work. Further the barrier 60 is made of continuous bubble foam which sufficiently catches aerosol but does not interfere with air flow.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to aerosol barriers for use in disposable pipette tips, and more particularly, to provide sufficient air flow through the disposable pipette tips for air flow liquid detection, but the disposable pipettes. It relates to a disposable pipette tip having an aerosol barrier made of absorbent open-cell foam that sufficiently shields droplets and aerosols from flow through the tip.

[0002]

Pipettes are devices commonly used in reagent experiments as liquid transfer devices for adding and mixing liquid components such as reagents and samples.

Early transporters were generally glass pipettes or tubes having hollow interiors that draw a liquid to their distal ends by applying a vacuum to their proximal ends. The vacuum was usually applied using the experimenter's mouth or by a suction valve connected to the proximal end of the glass pipette. These types of glass pipettes are often reused and therefore had to be very clean to prevent cross-contamination of reagents or samples.

Later, disposable pipette tips were introduced to avoid cross-contamination problems with reused pipettes and to aid experiments. The disposable pipette tip is connected to the end of a mechanical aspirator or pipettor and is designed to mate with the end of the mechanical aspirator so that only the vent from the mechanical aspirator is outside the proximal end of the disposable pipette tip. It was Mechanical aspirators typically use a plunger to force air through the aspirator to the outside of the proximal end of the disposable pipette tip, after which the proximal end is inserted from the supply container into the liquid to be aspirated. After placing the proximal end in the liquid, the plunger in the mechanical aspirator was loosened to depressurize the disposable pipette tip, thereby drawing the liquid from the supply container into the disposable pipette tip. The aspirated liquid contained in the disposable pipette tip was then administered to the target container using a plunger.

After use, the disposable pipette tip was generally extruded from the mechanical aspirator using a tubular or extrusion sleeve that exerts pressure on the top of the disposable pipette tip to push the pipette tip out of the mechanical aspirator. By extruding the disposable pipette tip from such a mechanical aspirator,
It was possible that an aerosol could be made from the residual liquid in the disposable tip on a mechanical aspirator. Furthermore, when liquid is drawn into a disposable pipette tip,
Aerosol may occur in the mechanical aspirator. Aerosol coming from the pipette tip to the mechanical aspirator can contaminate the mechanical aspirator and thus also other reagents or samples. One proposal to solve the aerosol problem has been to add a porous barrier between the liquid and the mechanical aspirator. Hydrophobic filter plugs typically made of, for example, polyethylene are used to remove liquids and aerosols from the end of the pipette tip to the mechanical aspirator without strongly affecting the aspiration and administration of liquids from disposable pipette tips. Blocked passage.

[0006] More recently, especially in labor-enhanced environments where high throughput or greater automation is desired,
Robotic suction devices have replaced manual mechanical aspirators. Robotic suction devices generally consist of stainless steel needles that suck liquid from the target container to the distal end by applying pressure to its proximal end, for example by hydraulic displacement. Of course, such robotic aspirators must be periodically cleaned to prevent cross-contamination of reagents or samples. Because of this problem, disposable pipette tips must be connected to a robotic suction device to reduce the risk of cross-contamination. However, when a robotic suction device is used in an automated environment, a controller of the device that detects when the end portion of the suction device is placed in the liquid of the target container is important. This problem is addressed by providing the robotic suction device with a liquid detection capability that prevents these ends from being pushed too far into the liquid. Generally, when using a metal or stainless steel needle,
Liquid detection can be accomplished by monitoring the capacitance of the needle, where changes in capacitance indicate insertion of the distal tip into the liquid. However, capacitance-based flow detection would not be possible without the more expensive, nonstandard disposable plastic pipette tips, generally conductive plastics. When using a standard non-conducting disposable plastic pipette tip, liquid detection was done by monitoring the airflow, where changes in airflow indicate that the liquid blocked the end of the pipette tip. To do.

However, when using air flow detection, one encounters the question of whether the disposable pipette tip contains a barrier to prevent the passage of aerosols by the robot to the aspirator. Aerosol filter barriers used in disposable pipette tips are often micro-hydrophobic plugs that create great resistance to air flow. Such barriers are too dense to allow enough air to flow, are detrimental to performing small amounts of pipetting, and do not work at all in automated robotic aspirators that use air flow liquid detection. Therefore, there is a need for new barriers in disposable pipette tips that capture sufficient liquid and aerosol from the flow to the aspirator by the robot, but provide sufficient air flow for the air flow liquid detection system to operate.

[0008]

SUMMARY OF THE INVENTION The present invention allows an air flow detection system for operation to provide sufficient air flow through a pipette tip to a robotic aspirator, but from a pipette tip to a robotic aspirator. Sufficient capture of liquids and aerosols overcomes the problems identified with prior art materials by providing a barrier for continued disposable pipette tips.

A preferred embodiment of the pipette tip of the present invention has a proximal end and a distal end, the proximal end being larger than the distal end and both ends comprising a cannula connected by a passage. A barrier is provided within the passageway of the pipette tip near the proximal end of the cannula and traps liquids and aerosols and prevents them from flowing out of the proximal end through the pipette tip. However, the barrier allows sufficient air to flow through the pipette tip to ensure proper operation of the air flow liquid detection system in the robotic aspirator. Preferably, the barrier is made of a superabsorbent open-cell foam that is sufficiently capable of entrapping aerosols but restricting air flow.

These and other aspects, features and advantages of the invention will be apparent from the following detailed description in conjunction with the accompanying drawings.

FIG. 1 is a perspective view of a pipette tip 10 according to the present invention for use in a manual or robotic suction device for performing liquid transfer in a laboratory.

The pipette tip 10 includes an open cannula 15 that is generally tapered conical and is defined by a cylindrical outer wall 17. Cannula 15 has an open proximal end 20 and an open distal end 25 with a plurality of optional annular step members 130, 135 and 140 on outer wall 17 therebetween. Cannula 15 also includes a plurality of ribs 45 projecting from outer wall 17 and extending vertically from proximal end 20 to distal end 25. Rib 45
Are provided to vertically support the pipette tip 10 when the pipette tip 10 is connected to the suction device.
The vertical row of axes is important for robotically connecting the pet tip 10 to a suction device, especially in the absence of mechanical visual aids.

Optional step members 130, 135 and 140 divide the cannula 15 into sections 30, 35 and 40, each step member 130, 135 and 140 having a respective step and proximal end 25 within the cannula 15. Represents a predetermined volume of liquid that will be located in between. These steps are used by the experimenter when visually measuring the amount of liquid aspirated during manual pipetting. For example, cannula 15
If the liquid level is aligned with the step member 130 within, the appropriate amount of liquid contained in the section 30 of the cannula 15 between the proximal end 25 and the step member 130 is 10 μl; A suitable amount of liquid in sections 30 and 35 when aligned with strip 135 is 50 μl; a suitable amount of liquid in sections 30, 35 and 40 when level is aligned with step 140. Is 100 μl. Preferably,
The total amount of liquid that can be retained in this usable part of the pipette tip 10 is about 120 μl. Of course, the above volumes are merely exemplary and the present invention is also conceivable and very convenient for larger or smaller pipette tips with or without steps.

FIG. 2 is a line 2- of the pipette tip 10 shown in FIG.
2 is a cross-sectional view along 2 showing a passageway 50 having a generally tapered cone shape extending from the proximal end 20 to the distal end 25.
As can be seen in FIG. 2, the passageway 50 extends from the proximal end 20 to the distal end
It is defined by an inner wall 57 of decreasing diameter towards 5. In accordance with the present invention, the foam barrier 60 is contained within the passageway 50 proximate the proximal end 20 and is preferably installed in that location using a light frictional fit. However, another method, gluing, can also be used to attach the foam barrier 60 in this position.

The foam barrier 60 is a continuous, similar to that shown in FIG. 3, having a web-like or filamentous structure in which air can flow through the foam but droplets or aerosols cannot pass through the foam. It is preferably an aerosol-adsorbing foam of cells.
FIG. 3 is an electron micrograph of an actual foam barrier 60 for use with the pipette tip 10 according to the present invention.
The foam barrier 60 having the structure of the present invention is a barrier to droplets and aerosols that flow through the passageway 50 from the proximal end 20 to the distal end 25 during the aspiration process or when the pipette tip 10 is extruded from the distal end of the aspiration device. As well, and limits the air flow required to perform automated air flow liquid detection.

During use, the pipette tip 10 containing the foam barrier 60 is attached to the distal end of the aspirator and held in place by friction at the distal end of the aspirator. When transferring a reagent or sample from a supply container to a target container, the end of the aspirator with pipette tip 10 thereon is moved over the supply container and slowly moved down into the liquid to be aspirated. When the disposable pipette tip is moved down into the liquid, the suction device causes an air flow through the pipette tip 10, which measures the change in air flow when the distal end 25 of the pipette tip 10 enters the liquid. To be monitored by the controller. If a drop in airflow is detected, the aspirator senses that the pipette tip 10 has entered the liquid and begins the aspiration method, where a vacuum is applied to the proximal end 20 to terminate the distal end 25 of the pipette tip 10. Aspirate liquid through and into passage 50. The depressurization is applied until a predetermined volume of liquid is drawn into the passage 50. The aspirator device then removes the pipette tip 10 from the liquid source container and carries the aspirated liquid to the target container for administration.

The suction device is a pipette tip 10 on the target container.
Position, air pressure is applied to the proximal end 20 to administer the volume of liquid in the passageway 50 to the target container. After dispensing the liquid into the target container, the suction device removes the pipette tip 10 from the target container and when residual liquid crosses the distal end 25,
Sudden movement of the pipette tip causes this residual liquid to become an aerosol. After the liquid transfer is complete, the aspirator pushes the pipette tip 10 from its distal end into a disposable container, vigorously displacing a large amount of air from the proximal end 20 of the passage 50 in the pipette tip 10 to cause an instant vacuum, and A high viscosity aerosolization of the residual liquid volume contained within the distal portion 25 of the pipette tip 10 occurs. However, the foam barrier
The 60 is constructed of a material designed to capture both such liquids and aerosols and prevent them from flowing into or through the suction device, as described above.

Cannula 15 is made of either plastic and foam barrier 60 is polyurethane,
It can be made of polyvinyl chloride or polyvinyl alcohol. Preferably, the foam barrier 60 is made from a melamine-based open cell foam having a density in the range 0.5-0.8 pcf, most preferably 0.7 pcf. Foams having these general properties are available from a number of supply components used as thermal and acoustic insulation. In particular, Willtec ™, available from Illbruck Inc. of Minneapolis, Minn., Is a flexible, lightweight, melamine-based open cell foam with a preferred density of 0.7 pcf. . In addition, Viltech ^™ foam is chemically resistant to organic solvents and a range of diluted acids and alkalis. Other physical properties of VILTEC ™ foam are as follows: Physical Properties Typical Value Test Method Tensile Strength 8.0 psi ASTM D3574-77 Tear Strength 0.3 lb / in ASTM D3574-77 Ultimate Elongation 8.0% ASTM D3574-77 Temperature Stability -60 ° C to 150 ° C Constant 250 ° C for up to 24 hours. This is an example. More importantly, as mentioned above, the foam barrier 60 must be made of a foam material that does not severely restrict the air flow through the foam barrier 60 but blocks droplets or aerosols passing through the foam barrier 60. I won't. An open cell foam structure, such as that shown in Figure 3, meets this requirement, and a discontinuous, ball-like or glove-like structure like that shown in Figure 4 also works. It was shown not to. Figure 4 is an electron micrograph of a prior art barrier found on a conventional aerosol filter pipette tip. The barrier shown in Figure 4 cannot provide sufficient airflow to allow airflow liquid detection performed by an automated robotic suction device. When a foam like the one shown in Figure 4 is used in a disposable pipette tip in an automated robotic aspirator, it is not Would be impossible.

Foam barrier 60 can be manufactured from Viltech ™ foam using conventional manufacturing techniques. For example, a cork punch can be used to shoot the "plug" shape of the foam barrier 60 from a 0.25 inch thick sheet of Viltech ™ foam. "Plug" shaped foam barrier 60
Is then inserted through the proximal end 20 of the pipette tip 10 and press fit into the passage 50 to a predetermined position. of course,
The manufacturing techniques and materials and machines used are for illustration only and various other manufacturing methods and materials can also be used.

In the above description, the embodiments described above are understood to be exemplary of a disposable pipette tip according to the invention having an aerosol adsorbing foam as a barrier to the flow of liquid without disturbing the air flow through the pipette tip. I want to be done. Of course, other suitable variations and modifications can be made to this embodiment and are also within the scope of the invention.

[Brief description of drawings]

FIG. 1 is a perspective view of a pipette tip of the present invention.

FIG. 2 is a cross-sectional view of the pipette tip shown in FIG.

FIG. 3 is a reproduction of a micrograph of a foam barrier in the pipette tip shown in FIG.

FIG. 4 is a photomicrograph of a foam barrier used in a conventional pipette tip.

[Explanation of symbols]

 10 Pipette Tip 15 Cannula 20 Base End 25 End 45 Rib 50 Passage 60 Foam Barrier

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Peter A. Bulldell, Pennsylvania, Pennsylvania, USA 17326, Glen Lock, Roster Road (no house number), R1, Box 16 Kay (72) Inventor Allen S. Reacher Coach House Drive 1 at Owing Mills, 21117, Maryland, USA

Claims (10)

[Claims] 1. A cannula having an open proximal end and an open distal end, the via having a passage extending from the open proximal end to the open distal end; and a barrier positioned within the passage, the barrier comprising: Made of open-cell foam capable of preventing aerosols from entering the distal end and passing through the passage to the proximal end without restricting air flow through the passage. Pipette tip for use in a suction device. 2. The pipette tip of claim 1, wherein the foam is an open cell foam having a web-like structure. 3. The pipette tip of claim 2, wherein the foam has a density between 0.5 pcf and 0.8 pcf. 4. The pipette tip of claim 3, wherein the density is 0.7 pcf. 5. The pipette tip of claim 1, further including means for removably attaching the pipette tip to the suction device. 6. The pipette tip of claim 1, wherein the foam is an absorbent foam. 7. The pipette tip of claim 1, wherein the foam is an open cell foam that is not hydrophobic. 8. The pipette tip of claim 1, further including means for vertically supporting the pipette tip when the pipette tip is robotically attached to the suction device. 9. The means for vertically supporting the pipette tip when the pipette tip is robotically attached to the suction device projects longitudinally from the cannula and from the proximal end to the distal end. 9. The pipette tip according to claim 8, comprising a plurality of ribs extending in the direction of. 10. The pipette tip of claim 1, wherein the foam is made of melamine-based open cell foam.