GB2247950A

GB2247950A - Multichannel pipette

Info

Publication number: GB2247950A
Application number: GB9020287A
Authority: GB
Inventors: Vasily Vasilievich Annenkov; Alexandr Sergeevich Kozlov; Vyacheslav Tarasovich Larin; Vladimir Viktorovich Ivanov
Original assignee: N PROIZV OB BIOLOG PRIBOROSTRO
Current assignee: N PROIZV OB BIOLOG PRIBOROSTRO
Priority date: 1990-09-17
Filing date: 1990-09-17
Publication date: 1992-03-18
Also published as: GB9020287D0; FR2667253A1

Abstract

The pipette has a casing (1) having a hole (4) in one of its walls and mounting on its upper wall a first handle (2) having a cylindrical internal cavity (3). A pusher (5) is located in the upper portion of the casing (1). The internal cavity (3) of the first handle (2) contains a rod (8) having its lower end secured to the pusher (5), while its upper end accommodates a button. Hinged to the pusher (5) at one end is a strip (13) whose other end is mechanically connected with a second handle (14). Upper ends of spring-loaded plungers (10) are hinged to the lower surface of the strip (13). Lower ends of the plungers (10) are disposed in the internal cavities of cylindrical members (9). The pusher (5) mounts an adjustable stop adapted for limiting movement of the strip and a means for adjusting stop position. <IMAGE>

Description

MULTICH@N@EL PIPETTE The present invention relates to facilities for chemical and physical laboratories and in particular to multichannel pipettes.

The invention may find apvlications in biochemical, biological and chemical research and in medi cite.

There is widely on a multichannel pipette (cf. SU, P, No. 959,612) com.prisinD a vertical casing made as a frame and mounting on its upper wall a first handle having a cylindrical internal cavity.

Arranged in the upper portion of the rectansular casing is a pusher made as a longitudinal sleeve.

The cylindrical internal cavity of the first handle acconmodates a rod installed coaxially with said handle and secured on one end to the pusher and also a shaft with a button attached to its upper end. The other end of the rod is connected with a drive element comprising a rack with a ratchet. Te ratchet of the drive element is connected with the shaft by means of a catch. The drive sleeve mounts a second handle fitted in a longitudinal opening provided in the side wall of the casing.Cylindrical members fixed in the lower portion of the casing are arranged in one plane in parallel with the side walls of the rectangular casing, lugs being attached to the lower end of said cylindrical members. The known multichannel pipette also comprises spring-loaded pistons having their first ends secured to the pusher and their second ends contained within the cylindrical members.

To take doses of liquid, the second handle is moved along the opening from the lower to the upper position whereby the pistons will move upwards due to the action of an intermediate link formed with the drive sleeve. Titus, vacuum is created within the cylindrical members and the liquid is sucked in the lugs.

To displace doses of the liquid, it is necessary to depress the button, its movement being transferred to the catch through the shaft. The lower end of the catch is pressed against the inclined surface of the ratchet tooth at the upper end of the rod.

The ratchet moves downwards over a distance equal to the pitch of the drive element, thereby moving the pistons and displacing a corresponding amount of liquid. When the button is released, the spring returns it to the upper position, due to which the catah is drawn away from the ratchet by means of a plate. As the button is depressed repeatedly, there occurs further axial displacement of the ratchet and movement of the pistons until they reach the final position and the liquid is completely displaced from the lags.

To obtain solutions with a linear concentration gradient, it is necessary to add repeatedly different amounts of solution of one concentration to solution having another concentration, which consumes much time and effort.

The object of the invention is to create a mul tichanel pipette, in which a novel structural embodiment would allow decreasing time required to obtain solutions with a linear concentration gradient.

There is provided a multichannel pipette comp- rising a rectangular casing having a hole in one of its walls and mounting on its upper wall a first handle having a cylindrical internal cavity, a pusher disposed in the upper portion of the rectangular casing and connected to a second handle instal- led in said hole in the rectangular casing, a rod arranged within the cylindrical internal cavity of the first handle coaxially with said handle and having its lower end secured to the pusher, while its upper end mounts a button, cylindrical members fixed in the lower portion of the casing and arranged in one plane in parallel with side walls of the rectangular casing, and spring-loaded plungers contained within the rectangular casing, lower ends of each plunger being in the internal cavities of the cylindrical members, while upper ends thereof are connected with the pusher, which, according to the invention, further comprises an additional strip arranged in the rectangular casing and having its one end hinged to the pusher and its other end linked mechanically with the second handle, the upper ends of the spring-loaded plungers being hinged to the lower surface of said strip, and also an adjustable stop adapted for limiting movement of the strip and a means for adjusting the stop position, said stop and said means being suitably secured to the pusher.

It is advantageous that a hole should be provided in the upper wall of the rectangular casing, the upper surface of the plunger having a projection with a central hole, said projection passing through said hole in the upper wall of the rectangular casing and extending beyond said rectangular casing, the adjustable stop adapted for limiting movement of the strip and the means for adjusting the stop position being preferably fastened on the projecting portion of the pusher.

It is also advantageous that, with a view to decreasing time required to obtain doses of solutions with a linear concentration gradient, the strip should have a hole in its secured end, the adjustable stop adapted for limiting movement of the strip be ing made as a rod having a boss on its lower end and arranged in said hole in the strip so that the strip moving downwards rests against the rod boss, the means for adjusting the stop position representing a screw fitted in the central hole in the projecting portion of the pusher and mounting on its lower surface a rigidly fastened upper end of the rod of the adjustable stop adapted for limiting movement of the strip, the hole suited to hold the second handle rigidly secured to the second end of the strip being provided in the side wall of the rectangular casing.

It is further advantageous that, in order to simplify construction of the multichannel pipette according to the invention, tle adjustable stot adap- ted for limiting movement o2 the strip should be made as a rod whose lower end interacts with the second end of the strip, the upper end of said rod mounting the second handle, the means for adjusting the stop position being made as a nut screwed on the external surface of the projecting portion of the pusher, the central hole in the projecting portion of the pusher being coaxial with the central hole in the nut, while the rod is disposed in the central hole in the projecting portion of the gusher and in the central hole in the nut in a manner allow- ing its movement along the axis of said holes.

The use of the multichannel pipette forming the subject of the present invention permits decreasing the time required to obtain doses (equal in volume) of solutions with a linear concentration gradient since the procedure of obtaining doses 0 solution.

4ith a linear concentration gradient taLes one dosing cycle, the range of linear variations o2 concentra- tion of solutions being dependent on the inclination angle of the strip, said range being adjusted with the stop limiting movement of te strip.

The invention will no be described further with reference to specific embodiments thereof, taken in conjunction with the accompanying drawings wherein: Figure 1 is a general view (longitudinal section) of a multichannel pipette according to te invention; and Figure 2 shows on an enlarge scale another e-- bodiment of an adjustable stop for limiting movement of a strip and a means for adjusting stop position (longitudinal section) a~corSing to the inve--tion.

Referring.. to the drawings the multichannel pipette according to tie invention comprises rectan- gular casing 1 (Figure 1)with its upper wall moun- ting a first handle 2 having a cylindrical internal cavity 3. A hole 4 is provided in a side wall of the rectangular casing 1.

4 pusher 5 is locate in the upper portion of the rectangular casing ?. The pusher 5 is made as a frame having an utter wall 6 and side walls 7. At- tached to the upper wall 6 of the pusher 5 by its lower end is a rod 8 arranged i the cavity 3 of the handle 2 coaxially with the internal cavity 5, the upper end of said rod accompdating a button (not shown in the drawing).

Fixed in the lower portion of the rectangular casing I are cylindrical members 9 placed in one plane in parallel with the side walls of the rectangular casing -1. The multichannel pipette according to the invention further comprises plungers 10 whose number corresponds to the number of channels in the pipette, the plungers being loaded with compression springs 11 and contained within the rectangular casing 1, lower ends of each plunger being placed in the internal cavities of the cylindrical members 9. The plun gers-lO in the cylindrical ineThers , are sealed by the use of rubber rings 12. The rectamgular casing 1 accommodates a strip 13, one end of which is hinged to the pusher 5, while its other movable end mounts a second handle I4 fitted in the hole 4 in the rec tanDular casing.The strip 13 represents a frame having an upper wall -15 and side walls I. The upper ends of the spring-loaded plungers 10 are hinged to the strip 13 by means of shafts I7 whose number corresponds to the number of the plungers I0, said shafts being secured to side walls 16 of the strip 13. Separable lugs 18 are attached to the lower ends of the cylindrical members 9.

A hole 19 is provided in the upper wall of the rectangular casing 1. The upper surface of the pusher 5 has a projection 20 with a central hole 2,, said projection passing through the hole 19 in the upper wall of the rectangular casing 1 and extending beyond the rectangular casing 1.

The proposed multichaniiel pipette also includes an adjustable stop adapted for limiting movement of the strip and a means for adjusting stop position, which are secured to the projecting portion 20 of the pusher 5.

The adjustable stop adapted for limiting movement of the strip is made as a rod 22 having a boss 23 on its lower end and installed in a hole 24 in the strip 13 so that the strip 13 moving downwards rests against the boss 23 of the rod 22. The means for adjusting stop position is essentially a micrometer screw 25, the upper end of the rod 22 being rigidly secured to a lower surface 26 of said micrometer screw. The screw 25 is screwed in the central hole 21 of the projection 20. A coarse scale 27 for measuring doses of liquid is marked on the projection 20. A fine cylindrical scale 28 for measuring doses of liquid is marked in the lower portion of the screw 25.

In another embodiment of the multichannel pipette, the adjustable stop adapted for limiting movement of the strip is made as a rod (Figure 2), its lower end interacting with the strip 13. The second handle I4 is fixed on the upper end of the rod 29.

The means for adjusting stop position is formed with a nut 30 screwed on the external surface of the projecting portion 20 of the pusher 5. The central hole 21 in the projecting portion 20 of the pusher 4 is coaxial with a central hole 31 in the nut 30. The rod 29 is installed in the central hole 21 in the projecting portion 20 of the pusher 5 and in the central hole 31 in the nut 30 in a manner allowirg its movement along an axis 32 of the holes 21 and 31.

The coarse scale 27 for measuring doses of liquid is marked on the projecting portion 20 in much the same manner as in the first embodiment of the invention.

The fine cylindrical scale 28 for measuring doses of liquid is marked in the lower portion of the external surface of the nut 30.

The multichannel pipette according to the invention operates in the following manner.

Two stages are required to obtain doses of solution with a linearly varying concentration. Initially, first liquid is taken into the separable lugs (Figure 1). The rod 8 is moved to the lower position by depressing the button (not shown in the drawing).

The plungers 10 linked with the pusher 5 through te strip I3 move to the lower position together with the strip If pressed by the springs 11 to the upper wall 6 of the pusher 5, thereby compressing the springs 11. The rod 22 of the adjustable stop adapted for limiting movement of the strip moves together with the pusher 5. All the plungers 10 travel an equal distance.

Thereafter the holes in the separable lugs I8 are immersed in the first liquid and the button is released. Under the action of the opposing springs 11, the rod 8 moves to the upper position in conjunction with the pusher 5 and the plungers 10. Equal doses of the liquid get into the separable lugs 18 due to a difference in pressure in the cavities under the plungers 10 and in the surrounding space. The amount of equal doses of the liquid in the separable lugs I8 corresponds to the distance covered by the plungers 10.

Next, a portion of the liquid is displaced. Turning the micrometer screw 25 and ref erring to the coarse scale 27 for measuring doses of liquid it is necessary to set the rod 22 of the adjustable stop adapted for limiting movement of the strip to a desired position. The second handle is operated to draw the movable end of the strip 13 downwards so that the strip 13 rests against the boss 23 of the rod 22.

The plungers 10 move over distances linearly increasing in the direction from the plunger 10 nearest to the point at which the strip 13 is hinged to the pusher 5 (distance covered by the plunger 10 is zero) to the plunger 10 farthest from said point.

During movement of the plungers I0, doses of the liquid varying in volume are displaced from the sepa- rable lugs I8 to suit a linearly varying distance covered by the plungers 10.

At the second stage, seco å liquid is taken in the separable lugs 18. This is done by operating t second handle I4 to keep the movable end of the strip 13 in close proximity to the boss 23 of t.s rod 22 of the adjustable stop adapted for limiting movement of the strip and immersing the holes in the separable lugs 18 in the second liquid.Following this, the second handle I4 is released and returns to the initial position together with the plungers 10 under the action of the opposing springs 11. The separable lugs 18 receive doses of tie liquid differing in volume to suit a linearly varying distance covered by the plungers 10. Next, the separable lugs I8 are introduced into receiving vessels, for example, cells of a base table for immunologic reactions (not shown iii the drawing) whereupon the rod 8 is depressed to bring the pusher 5 and the plungers 8 to the lower position, thus completely displacing the liquid from the separable lugs 18 into the receiving vessels.

SO, during one dosing cycle, there are obtained doses of solutions with a linear concentration gradient, said doses being equal in volume.

The multichannel pipette comprising the second embodiment of the adjustable stop adapted for limiting movement of the strip and the means for adjusting stop position operates in much the same manner as the first embodiment thereof.

At the first stage, doses of liquid changing linearly are displaced by moving the strip 13 (Figure 2) as pressure is applied to te movable end of the strip 13 by the rod 29 of the adjustable stop adapted for limiting movement of the strip. The rod 29 moves in the central hole 21 in the projecting portion 20 of the pusher 5 and in the central hole 3l in the nut 30 of the means for adjusting stop position on application of pressure to the handle 14.

The travel limits of the rod 29 are adjusted by the nut 30 in a manner similar to that used in the first embodiment of the multichannel pipette.

The present invention permits increasing efficiency of laboratory work in obtaining solutions with a linear concentration gradient.

Claims

WHAT WE CLAIM IS:

1. A multichannel pipette comprising a rectangular casing having a hole in one of its walls and mounting on its upper wall a first handle having a cylindrical internal cavity; a pusher disposed in the upper portion of the rectangular casing; a rod arranged in the cylindrical internal cavity of the first handle coaxially with said handle and having its lower end secured to the pusher whose upper end accomm - dates a button; cylindrical members fixed in the lower portion of the casing and placed in one plane in parallel with side walls of the rectangular casing; a strip arranged in the rectangular casing and having its one end hinged to the pusher, while its other end is mechanically connected with a second handle fitted in said hole in the rectangular cain; spring-loaded plungers having their upper ends hinged to the lower surface of the strip, lower ends of each plunger being contained within the internal cavities of the cylindrical members; an adjustable stop adapted for limiting movement of the strip and a means for adjusting stop position, which are secured to the pusher.

2. A multichannel pipette as claimed in Claim 1, in which a hole is provided in the upper wall of the rectangular casing; the upper surface of the pusher having a projection with a central hole, said projection passing through said hole in the upper wall of the rectangular casing and extending beyond the rectangular casing; the adjustable stop adapted for limiting movement of the strip and the means for adjusting stop position being secured to the projecting portion of the pusher.

3. A multichannel pipette as claimed in Claim 2, wherein the strip has a hole in its second end; an adjustable stop adapted for limiting movement of the strip being made as a rod having a boss on its lower end and fitted in said hole in the strip so that the strip moving downwards restsagaisst the rod boss; the means for adjusting stop position being essentially a screw driven in the central hole in the projecting portion of the pusher, the upper end of the rod of the adjustable stop adapted for limiting movement of the strip being rigidly secured to the lower surface of said screw; the hole accommodating the second handle rigidly fastened on the second end of the strip being provided in a side wall of the rectangular casing.

4. A multichannel pipette as claimed in Claim 2, wherein the adjustable stop adapted for limiting movement of the strip is essentially a rod whose lower end interacts with the second end of the strip, while its upper end mounts the second handle, the means for adjusting stop position being a nut screwed on the external surface of the projecting portion of the pusher; the central hole in the projecting portion of the pusher being coaxial with the central hole in the nut, the rod being 2installed in the central hole in the projecting portion of the pusher and in the central hole in the nut in a manner allowing its movement along the axis of said holes.

5. A multichannel pipette as claimed in Claims 1, through 4, substantially as hereinabove described with reference to, and as shown in the accompanying drawings.