KR20190053822A - pipette with no insertion force - Google Patents

Abstract

The present invention relates to an automatic pipetting device used in a liquid handling robot used for automation of experiments. According to the present invention, a pipette tip mounting mechanism does not require an insertion force when a pipette tip is to be mounted on a pipette, so that the mechanism is simple and the robot can be miniaturized.

Description

Pipette with no insertion force < RTI ID = 0.0 >

The present invention relates to an automatic pipette used in a liquid handling robot used for automation of experiments. When the pipette tip attachment / detachment mechanism according to the present invention is used, the mechanism is simple and the robot can be downsized because the insertion force is not required when attaching / detaching the pipette tip to / from the pipette.

Micropipettes are widely used to accurately transfer liquids in biochemical laboratories. Insert a disposable pipette tip into the pipette, transfer the liquid, and discard the pipette tip. Automated pipetting robots are widely used because routine routines repeat this process very often.

Figure 1. Typical Micropipette

A Cartesian robot moving along the X, Y, and Z axes is most common, attaching a pipette to the Z axis and automatically inserting or ejecting a pipette tip. Experimental automation equipment companies are offering a variety of products (Gilson, Hamilton, Hudson Robotics, Opentron, etc.)

Figure 2. Opentrons pipetting robot, NY, USA

In principle, when inserting a pipette tip into a pipette, four engineering problems must be solved. First, the pipette tip should not fall out of the pipette by itself. Second, air must not leak between the pipette tip and the pipette. Third, the pipette tip and pipette must be precisely secured and on the same axis. After the fourth use, the pipette tip must be easily removed from the pipette.

To solve this problem, the prior art produced a pipette tip in a cone shape, and the pipette gave a taper. As a result, the pipette tip and the pipette are held in place by friction and can be held in place by precise positioning

An annular protrusion is formed on the outer wall of the pipette. When the pipette tip is firmly inserted into the pipette, the protrusion is elastically deformed and acts like an O-ring, and air is not leaked. Since the pipette tip is fixed by frictional force, the pipette tip can easily be removed after peeling off by giving more force than this frictional force after use.

Figure 3. Pipette tip airtight, US, 6550349B1

     The friction force and the pipette tip attachment / detachment mechanism using the annular protrusion have been used almost unchanged for decades. This technology was invented by Heinrich Schmidter of the University of Marburg in Germany in 1957, patented in the same year and registered in 1961 (German Patent Office, 1,090,449). He used a spring-loaded piston and a removable plastic pipette tip, which was in principle nearly identical to current micropipettes

Eppendorf used pipette tips to mass-produce polyethylene / polypropylene resin while shrinking the pipette tips. On the other hand, Gilson Company of USA showed a micropipette that could change volume in 1974. In 1984, CAPP of Denmark invented the first remote channel pipette. Frequent use of a micropipette can cause carpal turnnel syndrome in the wrist. In 2002, Vistalab Technologies Inc. invented a rectangular, ergonomically comfortable pipette

On the other hand, the binding force (force applied when inserting the pipette tip) or detachment force (force exerted when the pipette tip is peeled off) often seems to be difficult for an experimenter using a pipette, and may cause problems in the wrist joints and muscles. To reduce this force, Gilleson invented a micropipette containing a sealing structure called a lip seal in 2017 (FR, 2017/051551).

Figure 4. Pipette with reduced insertion force using liposol of Gilson Company, KO, 10-2019-0019072

Pipette and pipette tips require constant strength when inserting. Friction is first needed. This frictional force provides the force required to mechanically coaxially fix the two devices. Elastic strains are also needed. The annular protrusion of the inner wall of the pipette tip is a force for elastically deforming and sealing.

At this time, since the elastic deformation force requires a very large force, a method of reducing this force is to form a lip seal widely used in vacuum piping on the surface of the pipette. Unlike the annular protrusion of the pipette tip, which requires a large force to be deformed to a degree of sealing, the lip seal formed on the pipette is easily deformed to ensure airtightness. According to Gilson's patent data, the force of 5N is sufficient to ensure sufficient insertion force and airtightness.

In some applications, however, the insertion force of the pipette tip needs to be close to zero. For example, in the case of a miniature pipette used in a small portable diagnostic apparatus, it is difficult to produce a mechanism that provides a strong insertion force. In this case, a pipette tip detachment / attachment mechanism that is not only coaxially fixed, but also sealing, and which does not require an insertion fastening force at the same time is required

 The present invention contemplates pipette and pipette tips of special shape to meet this need. Unlike the Gilson patent, this design uses a wax that is reversible in both the liquid and solid phases at a specific temperature without using a lipstick. As this material is highly sticky on the solid surface, It also provides a tightening force and ensures airtightness. On the other hand, since the liquid has low viscosity, the pipette tip can be easily removed or attached.

By mounting a heat source on the pipette tip and applying electricity to raise the temperature or to regulate the electricity to lower the temperature, the sealant formed between the pipette tip and the pipette can be freely changed to liquid or solid. For mounting, keep the solid down by lowering the temperature and raise the temperature to make the liquid phase.

Vaseline, laorin, and paraffin blend (Valap, Vaseline, Laoline, Paraffin mixture) are examples of topological materials suitable for such applications. Wrangling is a material used as an encapsulant for long-term storage of original biological tissue specimens (WO 2009076722A1). This material can be freely changed in liquid and solid phase by using temperature, which is convenient and harmless to human body. No harmful gas or gas is generated during the phase change process.

A pipette / pipette tip fastening mechanism is devised in which the above mentioned need requires little insertion force. By using this mechanism, the pipette tip can be attached or detached sufficiently with a weak force, and the airtightness can be maintained. Therefore, for example, the size of the automated pipetting robot can be remarkably reduced to make a miniature pipette. These ultra-small pipetting stations can also be used in portable diagnostic devices, which greatly enhances the convenience of field diagnostic devices.

To meet this need, the present invention firstly comprises a waxed pipette tip as a core element. When the structure of a general pipette tip is viewed, the portion for sucking or discharging the liquid is referred to as a tip portion, and the portion coupled to the pipette is referred to as a coupling portion.

The pipette tip according to the present invention has a unique shape in its coupling part and a radial circular flange is formed in the coupling part in a hat shape, which is the first element of the solution means of the present invention.

On the other hand, when a general pipette is placed, a portion that generates a vacuum suction force while moving up and down along the vertical axis is referred to as a vacuum cylinder, and a portion to be coupled with the pipette tip is referred to as a tip fastening portion.

In the pipette according to the present invention, the shape of the tip fastening portion is unique, and a cap-shaped radial circular flange is formed, which is the second element of the solution of the present invention

On the other hand, when the radial annular flange formed on the tip fastening portion of the pipette is placed, special parts are mounted on the bottom portion of the flange, that is, the portion to be coupled with the pipette tip, which is an annular thin film electric heater. When electricity is applied to this heater, heat is generated and the temperature of the flange is raised. When the electricity is cut, the temperature is lowered. This thin annular heater is the third element of the solution means of the present invention.

Finally, the flange of the joint of the pipette tip is coated with solid wax. While the flange of the pipette tip contacts with the flange of the pipette and melts in the heated flange due to the heater, the pipette tip is mechanically fixed to the pipette while maintaining airtightness. This solid wax is the fourth element of the solution of the present invention.

In summary, the present invention has the following basic structure through the above-mentioned four task solution means.

Basic element = pipette tip (first element) with flange + wax (fourth element) + thin film heater (third element) + pipette with flange (second element)

On the other hand, a thin film heater, which is a third element, may be embedded in the pipette according to the method of operation. A method of varying the temperature of the flange by incorporating a linear heater in the flange of the pipette.

Alternatively, a metal thin film pattern for heating may be electroplated, vaporized, coated with a heating coating material, or wound with a microfine wire (nichrome wire) on the flange surface of the pipette.

In another embodiment, the thin film pattern of the iron material may be printed on the flange and the temperature of the flange may be raised by external high frequency heating (also referred to as induction heating)

However, these various types of heater mounting methods can be called the third element of the thin film heater according to the present invention.

On the other hand, as the wax layer as the fourth element, a substance similar in properties to wax such as wax and limonene may be used in addition to the combination of paraffin / vaseline / raoline mentioned in the above description. .

Finally, although the coupling portion of the pipette tip of the first element and the pipette of the second element has been described as a radial annular flange in the above description, other modified structures are also possible.

For example, the flange of the pipette tip may be concave and the flange of the pipette may be convex by digging a concave-convex groove into the flange, which may be called a first element or a second element.

As another example, if the flange of the pipette tip has a male thread, and the flange of the pipette has a female thread, the structure is also included in the first and second elements of the present invention if the two joints are kept airtight by the wax.

However, it is preferable that the first, second, third, and fourth elements have the following form

1. The pipette tip is coated with a wax (second element) on the top flange (first element)

2. The wax layer is in solid form at room temperature

3 The flange (second element) of the pipette is attached with a thin heater (third element)

The pipette tip and the pipette according to the present invention are structured to ensure structural stiffness and airtightness with wax using electricity, and do not require strong insertion fastening force. For this reason, the pipetting robot can be miniaturized. Such a structure can be widely used in portable automatic diagnostic apparatuses

Hereinafter, the present invention will be described with reference to the accompanying drawings
Figure 1 is a representation of the relationship between a pipette, pipette tip, electric heater and wax
Figure 2 shows the structure of an electric heater
Figure 3 shows an example applied to an automated pipetting robot

First, a preferred embodiment of the present invention is shown in Fig. Figure 1 shows an example applied to a manual pipette. However, it can be applied to an automatic pipetting robot as shown in FIG. 3

Figure 1 is the most basic embodiment. A flange (1) is attached to the end of a body (6) of a pipette composed of a cylinder and a piston. A thin film electric heater ring 3 is attached to the flange and a wire 5 is connected.

On the other hand, the disposable pipette tip is provided with a flange 4 on which a top foreign matter is coated. Figure 1 shows four elements required for the present invention

First Element - Pipe Flange

Second element - Pipette tip flange

The third element - thin-film electric heater

The fourth element - wax layer

The two flanges face each other and the two flanges are firmly welded together as the flange becomes hot due to the electric heater and the wax melts (7). When the electric heater is turned off, the wax is solidified as the temperature is lowered, the bonding becomes firm and the airtightness is maintained. Turn the electric heater on after you finish using the pipette. As the temperature of the flange increases and the wax melts, the binding of the pipette tip loosens. At this time, the pipette tip can be removed.

The wax for fixing the pipette tip to the pipette varies according to the viscosity and melting point. In the present invention, three materials were mixed and used in various ratios.

for example,

50g vaseline + 50g lanolin + 50g paraffin

 When the components are mixed as described above, the melting point is in the range of 50 to 60 degrees Celsius (the exact melting point temperature varies depending on the type of raw material).

BeeWax instead of paraffin can increase melting point

step action Attach pipette tip Combining flanges Turn on the heater. The flange temperature rises. Liquid wax The wax melts and the flange is tightly bonded. Turn off the heater The temperature of the flange goes down.
The wax is hardened and the bonding of the flange becomes firm. Disconnect pipette tip Removing the flange Turn on the heater. As the wax melts, the flange connection becomes loose Pipette tip removal Remove pipette tip from pipette
Turn off the heater

An embodiment of the electric heater is shown in Fig. The heater is attached to the flange of the pipette and serves to raise the temperature of the flange. Preferably, the heater is in the form of a thin film ring, but other forms are possible. For example, a structure inserted into a flange is possible, and the flange surface may be thin-coated. If the flange itself is made of heating material, a separate heating element may not be necessary.

The present embodiment uses the heating element 11 as a separate component. A spiral thin film heater was made by etching a copper thin film layer (13) on a thin double-sided epoxy printed circuit board (12) having a thickness of 0.4 to 0.8 mm. An electrically conductive through-hole was drilled at both ends of the heater, and the electric wire (14) was soldered to the rear surface, and a long electric wire was connected to supply the electric power (DC12V) from the outside. The heater is fixed to the flange of the pipette using an adhesive. Temperature control was performed via a variable power supply. The temperature was measured using a non-contact infrared thermometer

Figure 4. Temperature control experiment of electric heater

FIG. 3 shows an example in which the present invention is applied to an actual pipetting station. The rectangular coordinate robot 25 moving along the X, Y, and Z axes is prepared. The pipette 21 is fixed to the Z axis of the robot. Prepare a 96-well plate. Fill the sample with reagent. Prepare the pipette tip 22 according to the present invention. The pipette (21) moves along the X, Y, and Z axes, locates and aligns the pipette tip, and moves down vertically to engage the pipette tip. Apply the power to the heater to raise the temperature of the flange and then lower it after a certain period of time. After the pipette tip is connected to the pipette (23), dispense the sample or reagent. After dispensing, move the pipette tip to the place where you want to dispose of it. Disconnect the pipette tip by applying electricity to the heater.

Claims (5)

Wherein the hollow tubular pipette (6) has a flange (1) at a lower end thereof, and an annular thin film heater (3) is provided on the flange surface,
The hollow tube-type pipette tip (2) has a flange at its upper end, and has a wax layer (4) on the flange surface that is solid at normal temperature and changes into a liquid when heated,
(i) when mounting the pipette tip on the pipette,
The flange of the pipette and the pipette tip are brought into contact with each other and the electric power is applied to the heater wire 5 to raise the temperature and the wax layer is melted so that when the pipette and the pipette tip are fused to each other, Adjusting the electricity to lower the temperature, thereby solidifying the wax layer to fix the pipette and the pipette tip; or

(ii) when the pipette tip is to be detached from the pipette, electricity is applied to the heater to raise the temperature, and the wax layer is melted to separate the pipette and the pipette tip;
Characterized in that it provides airtightness and strong bonding force without requiring a strong insertion force in the process of fitting and detaching the pipette tip

The apparatus of claim 1, wherein the heater for varying the temperature of the pipette comprises:
A thin film heater in which an electric resistance metal thin film pattern is formed on a pipette flange;
An annular thin plate heater of a printed circuit board material on which a copper thin film pattern for a heat source is formed;
An induction heater for coating the iron thin film on the pipette flange and for heating the iron thin film by using a high frequency generating source provided outside;
Characterized in that the pipetting mechanism The wax according to claim 1,
A phase change material comprising candle, paraffin wax, beeswax;
Wax viscosity modifiers including vaseline, lanolin; Lt; RTI ID = 0.0 >
2. The pipette tip according to claim 1,
Flange structure; Uneven structure; Cone type pipette tip and tapered pipette structure; Lt; RTI ID = 0.0 > The wax according to claim 1,
The shape coated on the flange surface of the pipette tip; Discrete, disposable wax flakes in solid form; A pipetting device

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