US3419051A

US3419051A - Density gradient system

Info

Publication number: US3419051A
Application number: US595199A
Authority: US
Inventors: Bert M Gustafson; Malter Lewis; Robert P Gustafson
Original assignee: Individual
Current assignee: BERT M GUSTAFSON; ROBERT P GUSTAFSON
Priority date: 1966-11-17
Filing date: 1966-11-17
Publication date: 1968-12-31
Anticipated expiration: 1985-12-31

Description

Dec. 31V, 1968 B. M. GusTAFsoN ET AL. 3,419,051

DENSITY GRADIENT SYSTEM Sheet Filed Nov. 17, 1966 ATTORNEYS Dec. 31, 1968 B. M. GusTAFsoN ET AL 3,419,051

DENSITY GRADIENT SYSTEM Filed Nov. 17. 1966 ATToQNEYs 3,419,051 DENSITY GRADIENT SYSTEM Bert M. Gustafson, 341 Princeton, Hotlman Estates, lll. 60172; Lewis Malter, 7741 Davis, Morton Grove, Ill. 60053; and Robert P. Gustafson, 7935 W. Belmont, Elmwood Park, Ill. 60635 Filed Nov. 17, 1966, Ser. No. 595,199 9 Claims. (Cl. 141-69) This invention relates to mixing and dispensing liquids, and more particularly to mixing and dispensing liquids of different densities, such as gradient solutions used to carry samples for analysis after sedimentation in a centrifuge.

Accordingly, the general object of the invention is to provide a machine for automatically mixing and dispensing liquids, such as gradient solutions, at a relatively high rate of production and reproducibly as compared with prior art systems.

A further object of the invention is to provide a density gradient system in which the solutions are driven from separate sources to a common mixing chamber in which the solutions are mixed after which the combined slutions are delivered to a piercing unit collector.

Another object of the invention is to facilitate the loading of density gradients into the respective chambers prior to mixing and to facilitate cleaning of the chambers after use.

Another object of the invention is to facilitate the quantitative predictable non-linear as well as linear gradient systems by interchanging various syringe pairs.

The invention also resides in a density gradient system n employing two syringes driven at the same controlled rate to deliver the gradient solution from one syringe to the other syringe for mixing and then from the latter to a collecting piercing unit.

Another object of the invention is to stir the combining FIGURE 3 is a sectional view taken along the line 3 3 of FIGURE 1 showing the carriage, its drive and controls.

FIGURE 4 is a sectional view taken along the line 4-4 of FIGURE 2.

FIGURE 5 is a diagrammatic view of the apparatus constructed in accordance with FIGURE l.

FIGURE 6 is a view of gears shifted to drive the carriage in a reverse direction.

As shown in the drawings for purposes of illustration, the invention is embodied in a machine 10 for mixing separate liquids, such as density gradient solutions of a light and heavier solution of sucrose, and for dispensing the combined liquids in the automatic and precise manner needed for density gradient solutions. The latter is the medium into which a sample of material is placed so that after a subsequent spinning of the sample and the gradient solution in a centrifuge, the sample separates and sediments at different rates in the gradient solution. After sedimentation, various layers of the gradient solution are analyzed by radiation or chromography techniques to determine the amount, if any, of the sample in the various layers.

Patented Dec. 3l, 1968 In accordance with the present invention two different liquids, such as a light and heavy Weight density solution of sucrose, are loaded into interior chambers 11 and 12 (FIG. 5) and the liquid from one chamber is continuously forced into the other chamber in which the combined uids are mixed by a stirrer 13 and a predetermined amount of combined liquids are dispensed from the mixing chamber through an outlet 14 to a collector. Also, in accordance with the present invention, the constantly flowing, combined liquid is accurately measured and stops limit the amount of material delivered to the collector so that the combined fluids may be collected and filled for a predetermined amount without the careful attention of an operator.

In this instance, the chambers 11 and 12 for receiving the light and heavy liquids are in the form of cylinders disposed horizontally above a support frame 16 and elongated cylindrical pistons 18 and 19 are disposed partially in the cylinders and are driven at their rearward ends by a connection to a motor driven carriage 20. Herein, the cylinders and pistons are in the form of conventional hypodermic syringes with the pistons constituting the usual plunger which is disposed in the close fitting bore of the cylinder of the syringe.

As the plunger 18 is driven by the carriage 20 further into the cylinder 11, the light weight liquid exits the cylinder through a tting 21 connected to one end of a conduit in the form of a tube 22 which is connected at its other end to an H fitting 24 leading to the interior of the cylinder 12. Therefore, as the plunger 18 moves to the left (FIG. 1), the light fluid is forced from the cylinder 11 into the heavy liquid in the cylinder 12.

For the purpose of mixing the liquids to afford a uniform mixture for the combined liquid being collected, the stirrer 13 stirs and mixes the liquids in the mixing chamber 25 which is the left end of the cylinder '12 (FIG. 1) immediately below the H fitting 24. Herein, the liquids are stirred while the fluid is flowing and being removed continuously from the mixing chamber, and to this end a T eon ball 27 with a metal rod therein is disposed in the mixing chamber and a magnetic driver 28 is disposed exteriorly of the cylinder and immediately beneath the mixing chamber, The driver is in the form of a T-shaped head having a pair of metal, magnetized arms of opposite polarity. The driver is journaled in an upper horizontal plate 30 of the frame for rotation about a vertical axis by a driving motor 31 (FIG. 5) secured in the frame beneath the driver. The speed and rotation of the magnetic arms of the magnetic driver is controlled by a rheostat control manipulated by a control knob 29 (FIG. 1). As the motor turns the driver, the ball moves about in the mixing chamber and during its movement mixes and stirs the two liquids of different densities prior to their leaving through the outlet tube 14.

To support the forward ends of the cylinders 11 and 12 in a plane parallel to the top plate 30, the forward ends of the Leur-Loks are detachably secured to a sleeve 32 (FIG. 2) on which is formed an exterior thread a semi-spherical swivel 33 (FIG. 2) for fitting in a complementary curved seat 34 in a plate 35 upstanding and extending transversely across the top plate 30 at the left end of the machine (FIG. l). To facilitate the ready attachment and disattachment of the syringes, the seats 34 open into upwardly extending slots 36 (FIGS. l and 2) and a small screw 37 (FIG. 2) is threaded to engage the vertical at rear surface on the swivel to prevent the removal of the swivel from its seat. As indicated in the dotted lines in FIG. 2 the swivel allows the cylinder body to slant or deviate slightly to maintain its alinement with the plunger as the plunger moves into the cylinder along a path advantageously alined with the axis of the cylinders. Thus, the cylinders and plungers are maintained in alinement to prevent breakage of the cylinders, which are usually formed from plastic or Acrylite, while affording a quick connect and disconnect support for the syringes at their forward ends. The forward ends of the sleeves 32 are formed with a quick connect and disconnect like a Leur-Lok fitting so that the

respective conduits

14 and 22 may quickly be attached or detached.

To connect the plungers 18 and 19 to the motor driven carriage 20, the right end of each of the plungers is coupled to a

drive rod

38 and 39 respectively, which are secured to the carriage 20. The left ends of the driver rods are formed of reduced diameter (FIG. and fitted in a telescoping manner in a sleeve formed at right ends of the plunger head. The drive rods extend longitudinally and horizontally from the plungers to a pair of spaced horizontal bores formed in the upper portion of the carriage and set screws threaded into the top of the carriage extend to fasten the rods to t-he carriage. The upper surfaces of the rods are formed with flats extending longitudinally along the rods for locking engagement with heads of the set screws (FIG. 3).

For the purpose of guiding the carriage 20 for rectangular movement longitudinally of the frame 16, a depending leg 40 (FIG. 3) of a T-shaped carriage block 41 carries a guide bushing 42 through which extends a longitudinally extending guide rod 44 fixed in the frame. Also serving to guide the carriage for longitudinal movenient is a lead screw 45 extending longitudinally beneath the slide rod and treaded in a nut 46 seated in a U- shaped opening 48 extending upwardly from the bottom of the block. Set

screws

49 and 50 are threaded from oppcsite sides of the T-shaped block to lock and hold the nut in the U-shaped recess. The slide rod and the set screw are secured to the frame and are disposed parallel to one another with their respective axes in a common vertical plane, and thus, the carriage block is guided for rectangular linear movement with the carriage moving through the elongated opening 51 (FIG. 3) formed in the top plate 30.

The carriage is adapted to be driven manually with turning of a control knob 52 (FIG. 5) fastened to the right end of the lead screw 44. The carriage is, also, power driven by a motor 54 (FIG. 5) connected by suitable gearing to rotate the lead screw in either the forward or the reverse direction. As illustrated, the motor drives a gear reducer 55 which drives a shaft to which is fastened a pinion gear S6. An axially slidable set of gears S8 and 59 are shifted between the solid line position of FIG. 5 for driving in the forward direction into the dotted line position for driving the carriage in the reverse direction. When the

gears

58 and 59 are in the lefthand position (FIG. 5) the pinion is connected to a large gear 60 secured to a shaft 61 carrying a small gear 62 to drive a gear 64 which is fixed to the lead screw to turn the latter with rotation of the driving motor. When the

gears

58 and 59 are shifted for reverse, as seen in FIG. 6, the gear 58 is connected directly to the -gear 64 fixed to the lead screw bypassing the speed reduction gears and 62 fixed on the shaft 61.

To control the amount of liquid being dispensed by movement of the carriage, a stop is provided for the carriage 20 which when engaged by the carriage causes operation of a micro switch 66 (FIG. 5) to open the motor circuit at contacts 68 for the driving motor 54. Herein, the depending leg 40 of the carriage block is formed with a stop finger 70 extending laterally and horizontally and movable longitudinally with the carriage to abut a stop block 71 carried on a threaded shaft 72 extending longitudinally between horizontally spaced frame walls 74 and 75 (FIG. 5). The ends of the threaded shaft are of reduced diameter and are journaled in the frame walls for turning with manual operation of a knob 76 fixed on the end of the shaft and extending exteriorly of the frame 16. The ends of the threaded shaft also slide axially in the frame walls when the stop block is engaged by the stop finger of the carriage and shifts the threaded shaft axially to the left (FIG. 5) to move an annular disk 7 8 xed to the left end of the shaft against a plunger 79 operating the contacts 68 of the micro switch. The amount of Contact plunger movement is very small and the plunger is spring urged to a closed position to shift disk 78 to the right when the `carriage is returned.

To determine the position of the stop block when calculating the amount of liquid to be dispensed, the stop block 71 has an upstanding indicator plate 80 guided in a narrow elongated slot 81 in the top plate 30. The elongated slot extends approximately the full width of the threaded shaft so that the stop block can be moved to one position along the length of the threaded shaft. A pointer 82 is secured by a screw to the plate 80 to indicate the position of the stop block on a scale 84 formed on the surface of the top plate.

The preferred manner of use of the invention will be described in detail hereinafter. Initially each of the syringes is removed from the machine and is lled to a desired amount as indicated by position of the plunger end relative to the indication on the cylinder. The preferred manner of filling the cylinders is to insert a needle in the Leur-Lok fitting 21 or 25 and force the fluid into the cylinder. During filling of the cylinder 12, a plug is inserted into the H fitting 24. After filling the cylinders, the swivels 33 on the sleeves 32 are seated in the front plate 35 and the retaining screws 37 (FIG. 2) are fastened. Thus, the left ends of the cylinders are supported by the upstanding frame support 35, the connection caps 85 and 86 of the plungers are then alined to receive the telescoping ends formed on the left side of the

rods

38 and 39. By loosening the set screws the rods are moved forwardly and fitted in the connecting caps 85 and 86. The set screws are then tightened to lock the guide rods to the carriage.

The operator will then move the carriage 20 forward by twisting the handle 52 and move the stop block 71 to a position to stop the dispensing after a predetermined amount of fluid is dispensed. Since both the syringes in the preferred embodiment dispense fluid simultaneously the indicator should be positioned for one half of the amount of fluid actually desired to be dispensed.

The plug (not shown) is removed from the H fitting and the connecting flexible conduit 22 is connected between the sleeve 32 for the cylinder 11 and the H fitting 24 of the cylinder 12. The delivery tube 14 is connected between the sleeve 32 for the cylinder 12 and the fitting on the collector 15.

The operator will then operate the knob 2-9 to turn on the stirring motor 31 which rotates the magnetic driver 28 to shift the stirrer ball 27 in the mixing chamber 25 at the end of the cylinder 12. When the stirrer driver is rotating uniformly and a good stirring action is taking place, the operator turns the control knob 87 to complete the circuit for the motor 54 which through gearing drives the lead screw 44 which in turn drives the carriage 20 to move simultaneously both plungers 18 and 19 into the respective cylinders at a uniform and controlled rate. The less dense fluid from the cylinder 11 moves through the conduit 22 into the mixing chamber 25 and is mixed by the stirrer ball withthe more dense liquid and simultaneously the plunger 19 is forcing the mixed liquid outwardly through the tube 14 to the collector 1S.

When the predetermined amount of combined liquid is dispensed, the finger 70 on the carriage abuts the stop block 71 and shifts the shaft 72 to the left (FIG. 5) to actuate the micro switch contacts 68 thereby opening the circuit for the electric motor. With the motor stopped no liquid is being dispensed, and the apparatus is available for the next operation.

The syringes may be readily cleaned to remove any remaining liquid therein which, if it is a sucrose solution, will dry and coat the cylinders, plungers and tubes if the sucrose is not removed. The plungers may be readily slid free from the cylinders and cleaned leaving the interior of the cylinders exposed for cleaning.

Another manner of using the present invention is that of forcing the sample and gradient, after sedimentation, to a suitable analyzer such as a chromography analyzer. If the sample is sedimented in a sucrose solution, each of the cylinders 11 and 12 are filled with the heavier sucrose solution. Then the motor 54 is de-energized. The sedimented sample tube is displaced in the collector 15. Then the collector cap 88 is threaded on the collector body and conduit 14 is disengaged from connector 32 and is replaced by a conduit to the analyzer. A needle 89 formed on the end of the tube 90 is connected to connector 32. The motor switch 87 is actuated to drive some of the solution through the outlet tube 14 and into the needle 89 to bleed the lines of air. The needle 89 is screwed into the fitting 91 formed on the bottom of the collector 15 and is screwedupwardly until it pierces the centrifuge tube and until the open end of the needle moves slightly into the solution within the centrifuge tube. With the stop block 71 set at the approximate position for the volume in the sample centrifuge tube, the motor 54 is operated to drive the carriage and plungers 18 and 19 to force the solution through the conduit 14 to the bottom of the centrifuge tube. The pressure of the incoming sucrose forces the gradient solution from the centrifuge tube out through the top of the centrifuge tube in a uniform manner. When the centrifuge tube is completely filled with excess solution, the carriage will actuate the stop block 71 to open the limit switch contacts 68 and stop the motor.

From the foregoing it will be seen that with the present invention gradient solutions may be automatically mixed and dispensed in a controlled manner, or alternatively a gradient sample may be dispensed from a centrifuge tube.

What is claimed is:

1. In a -mechanism for mixing and delivering liquids, comprising the combination of a support, a syringe on said support for receiving a quantity of a rst liquid, a second syringe on said support for receiving a quantity of a second liquid, a movable plunger in each of said first and second syringes for forcing fluid from the syringe with linear movement of the plunger in the syringe, a carriage connected to said plungers for simultaneously moving said plungers to force fiuid from said plungers, a conduit in fluid communication with said first and second syringes, a mixing chamber forming a portion of said second syringe for receiving said first liquid and said second liquid, a magnetic stirrer for stirring and mixing said liquids in said mixing chamber, a delivery conduit connected to said mixing chamber through which the mixed liquid may leave the mixing chamber, a collector for receiving the mixed liquid from the delivery conduit, and a motor to drive said carriage at a controlled rate to force the plungers to push the liquids continuously from the syringes and through the mixing chamber to the collector.

2. The combination of claim 1 including means for stopping said carriage after a predetermined amount of movement and of displacement of liquids from the syringes to the collector.

3. The combination of claim 2 in which said motor is an electric motor and in which said stopping means for the carriage includes an electrical switch for disconnecting the drive of the electric motor from the carriage.

4. The combination of claim 1 in which each of the syringes includes an outer cylinder disposed about said plunger, each of said cylinders being supported only by its plunger at one end, and a freely turnable member connected between the support and the cylinder at the other end of the cylinder, said member turning on said support to maintain alinement of the cylinder with the plunger to prevent binding of the plunger in the cylinder.

5. The combination of claim 4 wherein said carriage and said plunger are provided with telescoping members for effecting a quick connect and disconnect of the plungers to the carriage.

6. The combination of claim 1 including a manual drive ymeans for shifting said carriage to an initial position during a setup operation prior to operation of said motor.

7. In a device for mixing and for dispensing liquids, a support, a first liquid chamber on said support for receiving a first liquid, a second liquid chamber on said support for receiving a second liquid, a mixing chamber forming a portion of said second liquid chamber for mixing said fluids, means having a passageway connecting said first chamber to said mixing chamber, means for forcing the first and second liquids to flow simultaneously and in equal proportions from the first and second chambers and through said mixing chamber at a continuous controlled rate, a stirrer in the mixing chamber for stirring the liquids together as they move through the mixing chamber, and -means including an outer passage connected to said mixing chamber to afford an outlet through which said mixed liquids leave at a controlled rate.

8. In a machine for combining different densities and for dispensing the same, the combination comprising, a support, a first syringe mounted on said support for receiving a solution of a first density, a second syringe on the support for holding a quantity of a solution of a greater density, a conduit from the first syringe to deliver the lighter density solution to the second syringe adjacent a discharge end of the second syringe, stirring means including a member disposed in said second syringe adjacent its discharge end, a magnetic driver in said stirring means mounted on the support for driving by -magnetic force the member inside the second syringe, a plunger in each of the respective syringes for moving longitudinally to force the solution from the first syringe through to the second syringe, means for simultaneously driving both of said plungers at a predetermined rate to force fiuid from said first syringe into said second syringe and to force combined mixed solutions from said second syringe, and means for stopping the driving means after a predetermined quantity of solution is dispensed.

9. The combination of claim 8 including a stop means for stopping said driving means from forcing a quantity of liquid from said mixing chamber after a predetermined quantity of liquid is delivered.

References Cited UNITED STATES PATENTS 3,242,881 3/1966 Schafer 222-145X HOUSTON S. BELL, JR., Primary Examiner.

U.S. Cl. X.R.

Claims

1. IN A MECHANISM FOR MIXING AND DELIVERING LIQUIDS, COMPRISING THE COMBINATION OF A SUPPORT, A SYRINGE ON SAID SUPPORT FOR RECEIVING A QUANTITY OF A FIRST LIQUID, A SECOND SYRINGE ON SAID SUPPORT FOR RECEIVING A QUANTITY OF A SECOND LIQUID, A MOVABLE PLUNGER IN EACH OF SAID FIRST AND SECOND SYRINGES FOR FORCING FLUID FROM THE SYRINGE WITH LINEAR MOVEMENT OF THE PLUNGER IN THE SYRINGE, A CARRIAGE CONNECTED TO SAID PLUNGERS FOR SIMULTANEOUSLY MOVING SAID PLUNGERS TO FORCE FLUID FROM SAID PLUNGERS, A CONDUIT IN FLUID COMMUNICATION WITH SAID FIRST AND SECOND SYRINGES, A MIXING CHAMBER FORMING A PORTION OF SAID SECOND SYRINGE