Multiple Pipette

Abstract

A multiple pipette has inside its body a piston mover rod which is provided with a push button at its upper end and surrounded by a spiral spring. Once the rod has been pressed downwardly, the spring returns the rod to its original position so that liquid is sucked into containers connected with the lower ends of the cylinders and provided with points. The rod can be pressed down again against the spring force for discharging the liquid from the containers.

Description

BACKGROUND OF THE INVENTION

This invention relates to an improved multiple pipette having inside its body a piston mover rod which is provided with a press button at its upper end and surrounded by a spiral spring which, after the rod has been pressed down, returns the rod to its original position so that liquid is sucked into containers connected with the lower ends of the cylinders and provided with points, and which rod can be pressed down again against the spring force for discharging the liquid from the containers.

Pipettes which can be used for pipetting simultaneously several equal samples from separate receptables into other receptables are previously known.

A drawback of a previous sampling device according to Finnish Patent No. 41 466 is that both hands are needed when using it, and that the filling stroke is equal to the discharging stroke in the mechanism. So it is always possible that the points where the samples were sucked, are not drained completely empty. Previously known is also a multiple pipette according to Finnish Patent No. 44 069, having such a size and a shape that it is easy to handle with one hand so that the other hand can do something else, for instance hold a tube stand into which the liquid is to be transferred. Further, this device has a two-step piston stroke, but the sampling device according to Finnish Patent No 41466 is not provided with that. First, the pistons move down a certain distance to the filling position, and wnen returning up, they suck a certain volume of liquid into the points. When discharging, the pistons can be pressed down the distance that was required for filling, and then the piston movement can be carried a small distance further down from the filling position in order to drain the points completely.

SUMMARY OF THE INVENTION

The pipetting operation of a multiple pipette according to this invention is closely similar to the operation of the above described multiple pipette according to Finnish Patent No. 44 069. However, in practise several structural points have been found to require attention. The drawbacks and defects have been eliminated in a multiple pipette according to this invention, the characteristics of which are set forth in the claims. The construction of the pipette according to this invention is essentially different and this results in a much easier operation by one hand only. The construction has been changed so that the friction is as small as possible. Attention has been paid also to ergonomic points.

The multiple pipette is provided with a scale so that the setting for various volumes is easy and simple.

A test tube element is an essential part to the multiple pipette according to the invention. The size of the test tube element is such that it can be held by one hand while pipetting into it is done by the other hand. The test tube element comprises several tubes in a supporting plate, either fixed or loose. The distance between the tubes correspond to the distances between the points of the multiple pipette.

One advantage of the test tube element according to the invention is that its size is such that it can be shaken as a whole by a Rotamixer .sup.R, for instance, so that the liquid in each tube is effectively mixed without being spilled out from the tubes of the test tube element. The test tube element also comprises a lid which simultaneously closes all the tubes of the test tube element. This enables the storing of liquid in the tubes or the shaking of the test tube element by tilting it upside down, for instance. Further, one edge of the test tube element is provided with a mark or a code, made either when casting the element or later. This mark or code enables the recognition of the test tube element either visually, mechanically or electronically. Further, it indicates the position of the test tube element so that the individual tubes can be identified. In this way, the coding of each individual tube is unnecessary.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further illustrated by the following description of the construction and the operation of the multiple pipette with reference to the accompanying drawings, in which

FIG. 1 shows a side view of a multiple pipette according to the invention, in a section,

FIG. 2 shows a transverse section of the multiple pipette of FIG. 1, taken on line A--A,

FIG. 3 shows a side view of the lower part of a multiple pipette according to another embodiment of the invention, in section,

FIG. 4 shows the simultaneous joining of the points to the multiple pipette according to the invention by means of a point supporting plate and an instant joiner,

FIG. 5 shows a section taken on line B--B in FIG. 4,

FIG. 6 shows a side view of a test tube element according to the invention, in section,

FIG. 7 shows a section of the test tube element of FIG. 6, taken on line C--C, and

FIG. 8 shows the lid of the test tube element, in section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the drawings, the multiple pipette comprises two functional sections: a handle section I and a piston section II.

The handle section I has a setting portion operated on micrometer screw principle. It also contains parts that transmit the movement of a press button 1 to a piston mover 14 which is common to all pistons.

According to FIG. 1, the outer surface of the sleevelike body 3 of the handle section has a thread with a certain pitch, corresponding to the tread on the inner surface of a setting sleeve 4. The outer surface of the body 3 is provided with an axial scale. The inner surface of a locking sleeve 5 also has a thread corresponding to the thread of the body 3. Between the setting sleeve 4 and the locking sleeve 5 there is a threadless, transparent ring 6, moving at a small clearance in relation to the body. At the lower end of the setting sleeve 4 there is a scale ring 7 having a scale on its circumference. The axial scale on the body and the scale ring 7 attached to the setting sleeve together operate on micrometer screw principle so that the position of the body and the setting sleeve in relation to each other can be linearly and infinitely varied and can be seen on these two scales.

A sleeve 9 is arranged axially slidably at the upper end of the setting sleeve 4 around the rod 2 of the push button 1. The sleeve 9 is forced to its upper position by a spring 11 between the sleeve 9 and a locking ring 10. The rod 12 of the mover 14 of the piston 17 extends inside the body 3. The rod is forced to its upper position by a spring 13, and at the same time the push button rod 2, which abuts the rod 12, is forced to its upper position. The handle section I is joined by a threaded connection to the upper casing 15 of the piston section II.

The micrometer screw scale of the multiple pipette, operating infinitely and linearly, and comprising the scale 7 on the circumference of the setting sleeve 4 and the axial scale on the body 3, is calibrated by means of a screw sleeve 30 (FIG. 4) when assembling the multiple pipette. By turning the screw sleeve 30 either clockwise or counterclockwise, the sleeve 9 is moved, and the distance a is changed correspondingly. The liquid volume received at the points 29 used as liquid containers corresponds to the distance a, and the volume can be read directly on the micrometer screw scale.

The casing of the piston section II comprises a flat upper casing 15 and a cylinder casing 16 attached to the lower surface of the upper casing. The axially moving piston mover 14 common to all the pistons is placed inside the casing and joined by a threaded connection to the rod 12.

The pistons 17 are connected with the piston mover 14 either by a common connection piece 18 as shown in FIG. 1, or each piston separately by a connection piece 19 as shown in FIG. 3.

Between the upper end of each piston and the connection piece 18 or the connection pieces 19 there is a clearance so that the pistons 17 should move as frictionlessly as possibly in the cylinders 20 inside the cylinder casing 16.

In order to still improve the sideways movability, a ball 8 is placed between each piston 17 and the piston mover 14, as shown in FIG. 1. The axial movement of the pistons in relation to the piston mover 14 is prevented by springs 21 (FIG. 1) or springs 22 (FIG. 3). The spring force of a spring 21 is greater than the friction force between a piston and an O-ring 24 at the lower end of the piston. In FIG. 3, the lower end of each piston is air-tightly closed by a plug 23.

The pistons 17 extend parallel into the cylinders 20 inside the cylinder casing 16. The O-ring seals of the pistons are placed at the upper ends of the cylinders 20. The force of a stay 25 arranged on the O-rings, is adjustable by bolts 26 through springs 27, so that the tightness of the O-rings in relation to the pistons can be adjusted.

The parallel cylinders 20 are extended by sleevelike extensions 28. Plastic points 29, which are used as liquid containers when pipetting and which can be changed, are attached to the extensions 28 by pressing.

In FIG. 4, the points 29, used for liquid containers of the multiple pipette, are made so that they are fixed in the supporting plate 32 or pressed into the holes in the supporting plate 32. This supporting plate with the points is joined to the multiple pipette so that the sleevelike extensions 28, acting as cylinders 20 or cylinder extensions for the pistons 17, are fitted with a small clearance inside the points 29 in the supporting plate 32. In this way, each point 29 is guided to the location of the corresponding cylinder 20. O-ring seals 31, for instance, are arranged at the base of each sleevelike extension 28. When the supporting plate 32 is pressed by the instant joiner 33, attached by a threaded connection to the casing 16, the points 29 in the supporting plate are joined air-tightly to the extensions 28 by means of the O-rings 31. The multiple pipette is now ready for use, and equal liquid volumes to be transferred can be sucked by means of the pistons 17 into each point. Each point 29 is detached simultaneously together with the supporting plate when the instant joiner 33 is opened, and the supporting plate can be replaced quickly by another one with clean points.

A test tube element shown in FIGS. 6 to 8 is an essential part of the invention. The pipetted liquid volumes are transferred into this test tube element. It comprises a supporting plate 34 and test tubes 35, either fixed or loose in the plate. The position and the number of the tubes correspond to the position and the number of the points of the multiple pipette. The test tube element can be closed by a lid 36. The lid is provided with plugs 38 which are positioned and made so that they fit tightly at the tops of the corresponding tubes. By means of the lid 36, all the tubes of the test tube element can simultaneously be closed tightly. In order to visually note the position and the possible number of the test tube element and at the same time to identify the individual tubes, one edge of the test tube element is provided with a clearly noticeable notch 37, which is made when casting the element or later. The notch can be replaced by some other mark, such as number, letter or code, which can be recognized also in some other way than visually. Besides visual recognition, electronic or mechanic regocnition can be applied.

By means of a multiple pipette according to the invention, several equal liquid volumes can be transferred simultaneously. The multiple pipette in FIG. 1 comprises nine points 29, at equal distances from each other, and it is possible to transfer desired equal liquid volumes in each point. By means of the multiple pipette, liquid can be transferred into each test tube of the test tube element shown in FIGS. 6 to 8, or from one test tube element into another one.

The construction of the multiple pipette is such that it can be easily handled by one hand. The push button 1 is pressed into the sleeve 9 a distance allowed by the primary stroke a, and the multiple pipette is now ready to be filled. The points 29 of the multiple pipette are then submerged about 1 cm below the liquid surface. When the push button 1 is released, the spring 13 through rod 12 forces the piston mover 14 with the pistons 17 to the upper position, and the underpressure in the cylinders 20 causes a liquid volume corresponding to the primary stroke a to be sucked into each point.

Discharging of the multiple pipette is done by pressing down the push button 1 the distance a of the primary stroke. After this pressing is continued until the sleeve 9 is pressed down a distance b of the secondary stroke, and in this way the points are drained completely. The spring 11 returns the sleeve 9 to its upper position when the press button is released and the spring force brings the press button to its upper position.

The multiple pipette can easily and quickly be set for various volumes by changing the length of the primary stroke.

The setting is done by turning the setting sleeve 4 either clockwise or counterclockwise in relation to the body 3 so that the length a of the primary stroke either increases or decreases. As mentioned earlier, the setting sleeve 4 is provided with a fixed scale ring 7 having a scale on its circumference. The body 3 is provided with an axial scale. The scales of the setting sleeve and the body can be read as a micrometer screw scale. On this principle, the multiple pipette can be set linearly and infinitely, and the volume to be pipetted can be read directly on the micrometer screw scale.

The setting sleeve is locked in a desired position by the locking sleeve 5 by turning the locking sleeve tightly against the transparent ring 6 so that the ring is pressed against the setting sleeve 4 and holds it in a desired position.

The multiple pipette is ready for use when the setting sleeve is locked in a position for a desired volume. The scale on the body is visible through the transparent ring 6, and the set volume of the multiple pipette can be seen. By using a multiple pipette and test tube elements according to the invention, a great number of desired liquid volumes can be quickly pipetted when doing dilution series or enzyme incubations and sampling, for instance.

The operation and the design of the multiple pipette is such that pipetting is not straining.

The invention is, of course, not limited to the above embodiments and it can be considerably varied in details within the scope of the claims. So for instance, the multiple pipette can be operated by a programmed electric step motor, instead of manually, so that the significance of the primary and secondary strokes of the multiple pipette is taken into account. It should be noted also that the number of the points of the multiple pipette and correspondingly the number of the tubes in the test tube element is not necessarily nine, the number can be either smaller or greater.

Claims

I claim:

1. A multiple pipette comprising a body, a piston rod disposed within the body, a push button attached to one end of the piston rod, a plurality of containers for holding liquid, a plurality of cylinders connected to the containers, a plurality of pistons within the cylinders, a plurality of O-rings surrounding the pistons, spiral spring means surrounding the piston rod for returning it to a position in which the containers are filed after the push button has been pressed, and connecting means for connecting the pistons to the cylinders while permitting sideways movement of the pistons, the connecting means including connecting spring means that restrains axial movement of the pistons in relation to the piston rod, said connecting spring means having a force that exceeds the friction force of the O-rings.

2. The apparatus of claim 1, further comprising an O-ring stay for positioning the O-rings, a plurality of springs for positioning the O-ring stay, and a plurality of bolts for adjusting the force of the O-ring positioning springs.

3. The apparatus of claim 1, further comprising a joiner member by which the containers are interconnected and means for guiding and positioning the containers, said guiding means including sleeve-like extensions attached to the containers and air tight seals contacting the extensions.

4. The apparatus of claim 1, further comprising setting means for adjusting the stroke of the pistons, said setting means including a rotatable setting sleeve, a scale for indicating the adjustment of the setting means and a transparent ring through which the scale can be read.

5. The apparatus of claim 4, further comprising locking sleeve means for locking the position of the setting spring.

6. The apparatus of claim 4, further comprising a micrometer scale and calibrating means cooperating with the micrometer scale for changing the volume of each container.