US3525264A - Micropipette holder - Google Patents

Description

Aug. 25, 1970 FIG 5 T. T. NIEGLOS ET AL MIGROPIPETTE HOLDER Filed April 5. 1968 United States Patent O 3,525,264 MICROPIPETTE HOLDER Thomas T. Nieglos, Clifton, and Kenneth J. Cybulsky,

East Paterson, NJ., assignors to Becton, Dickinson and Company, East Rutherford, NJ., a corporation of New Jersey Filed Apr. 5, 1968, Ser. No. 719,173 Int. Cl. G01n 1/14 U.S. Cl. 73-425.6 10 Claims ABSTRACT OF THE DISCLOSURE A holder for capillary tubes and the like including an elongated barrel having dual position gripping means affixed to one end thereof and adapted to receive and retain a capillary tube in a tube gripping position, and variable air displacement means to create a pressure differential between the barrel interior and the outside atmosphere. The holder is also provided with means for shifting the gripping means from the gripping position at which the capillary is securely engaged to a releasing position at which the capillary may freely fall out of the holder.

BACKGROUND OF THE DISCLOSURE In many medical and technical reserach and experimental projects, technicians must often transfer small exact quantities of fluid from one vessel to another vessel or liuid receiving material. This task may conveniently be accomplished by drawing a precise quantity of the fluid to be transferred into a small bore tube or pipette by aspiratory or capillary action and thereafter releasing the iiuid into the proper container or material. Often these tiuds are radioactive, pathogenic, toxic, or contaminated and may be quite harmful if brought into physical contact with personnel or equipment and hence, disposable tubes or pipettes are extensively used. In addition, disposability eliminates the washing of tubes.

SUMMARY OF THE INVENTION The present invention relates to a device for holding such disposable tubes and it is the principal object of this invention to provide a reusable holder which can receive and retain a disposable capillary tube and which is adapted to facilitate the filling and emptying of such a tube. A further object is to provide such a holder with means for ejecting each spent capillary tube after use, so that the technicians using the tube need never come in contact therewith and so that the holder is maintained free of contamination by the fluids drawn into such tube.

These and other objects and advantages are most effectively attained in accordance with the present invention by providing a capillary tube or micropipette holder having an elongated hollow barrel member with gripping or chuck means affixed in one end thereof and air displacement means extending through the other end and positionable therein. The gripping means is adapted to be shifted from a tube gripping position at which the chuck will securely engage a micropipette tube inserting therein to a tube release position at which the pipette is free to fall from the holder. The air displacement means includes an elongated rod or plunger extending into the barrel interior and slidably sealed thereto. A control ring is affixed to the rod end extending outside the barrel so that by moving the gripping ring toward or away from the barrel, the technician may alter the pressure differential within the barrel so as to assist in filling or emptying a capillary engaged in the chuck. A vent hole extends through the barrel and cooperates with the rod in controlling the internal barrel air pressure so that a great degree of accuracy may be attained in filling and emptying pipettes retained in the holder.

3,525,264 Patented Aug. 25, 1970 ICC DESCRIPTION OF THE DRAWINGS FIG. l is a side elevational view of a pipette holder in accordance with the present invention;

FIG. 2 is an enlarged side elevational sectional view taken along the line 2 2 of FIG. 1;

FIG. 3 is an enlarged fragmentary side elevational sectional View of the chuck and chuck release portions of the pipette holder of the present invention;

FIG. 4 is a sectional plan view taken along the line 4-*4 of FIG. 3; and

FIG. 5 is a fragmentary side elevational view depicting the pipette magnification feature of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now made to the drawings and in particular to FIGS. 1 and 2 wherein a pipette holder 10 in accordance with the present invention is depicted as comprising an elongated barrel assembly 12 having forward and rear portions 14 and 16, respectively, securelysealed in an airtight fashion to one another by a snap iit arrangement occurring at the interface 18 therebetween. The barrel front portion 14 is formed of a transparent material such as glass or plastic, as for example, acrylic resin, which allows the operator of the holder to view the barrel interior. The rear barrel portion 16 is designed to facilitate handling and may be provided with a plurality of spaced parallel gripping rings 24 as depicted in this preferred embodiment. A vent hole 26 is disposed in the rear portion of the barrel extending through the barrel wall and communicating with the barrel interior.

The terminal portions 20 and 22 of the barrel at the front and rear of the barrel, respectively, provide reduced diameter access to the barrel interior. Plunger rod 28 extends through rear terminal portion 22 terminating at its free end outside of the barrel in a control loop 30. The terminal portion 22 of the rear barrel portion 16 is designed to provide airtight cooperation with plunger rod 28 as the latter is reciprocally passed therethrough. Rod 28 must be suiiiciently long so that when the rod is completely inserted in the barrel and the chuck 32 is in the extended position depicted in FIGS. l and 2, the forward end of rod 28 will contact the rear surface of pipette ejector or chuck release 34 which is disposed within the barrel interior at barrel end portion 20. Also, the plunger length must be such as to prevent the plunger from pushing the chuck completely out of the barrel. A more cornplete discussion of the interrelationship between the rod 28, chuck 32 and chuck release 34 will follow forthwith.

Rod 28 is free to be shifted longitudinally into the barrel interior and in this regard, gaskets may be provided in the reduced diameter barrel terminal portion 22 of this barrel to assure the airtightness of the fit between the plunger 28 and barrel end portion 22. In this regard, the gaskets must be such as to allow the plunger to be freely shifted longitudinally in and out of the barrel interior. In one successful practice of this invention, the rear body portion 1-6 of the holder was formed of polyethylene which is suiiiciently resilient and pliable to permit the rod to be longitudinally shifted into and out of the barrel interior through the barrel end portion 22 while retaining the necessary airtight seal between the plunger rod 28 and barrel interior to prevent any air leakage or by-pass.

A reduced diameter opening 3S is provided in front barrel end portion 20 and chuck 32 is disposed within this opening having portions extending Within the barrel and other portions exterior to the barrel. In this regard, reference is now made to the pipette chuck which is generally designated by the numeral 32 and is depicted most clearly in FIGS 2 and 3. The chuck is a substantially elongated member having front and rear annular flange sections 36 and 38, respectively, defining the ends of an intermediate shank portion. The shank is similarly divided into reduced diameter front and rear portions 40 and 42 which, in turn, are of differing diameters. Chuck 32 may be formed from any of various elastomeric materials including natural and silicon rubber. The material chosen, however, must be sufficiently pliable to deform when a slight stress, such as that which a technician could apply with his finger, is applied thereto.

The forward fiange 36 of chuck 32 is considerably larger than the opening 35 in the front barrel end portion 20 and it is located outside the barrel so that it serves as a stop to prevent chuck 32 from being forced into the barrel interior. The diameter of the rear flange 38 is also greater than the diameter of opening 35 and serves as a rear stop t prevent the chuck from being entirely expelled from the barrel during use and particularly when a pipette is ejected from the chuck.

As seen in FIG. 2, the normal diameter of front portion 40 of the chuck shank is greater than the opening 35 in the front closure while, as seen most clearly in FIG. 3, the diameter of rear portion 42 of the chuck shank is less than that of opening 35. A bore 44 extends through the chuck 32. The bore diameter is slightly larger than the outside diameter of the pipette or capillary tube to be secured in the holder so that a pipette may easily be slipped through the bore. In this regard, the front and rear terminals of bores 44, 46 and 48, respectively, are countersunk or enlarged to facilitate insertion of the pipette 50 therethrough.

It is to be appreciated that within the boundaries defined by anges 36 and 38, the chuck is free to be longitudinally shifted back and forth relative to barrel I12 although some slight force will be necessary to position the rear end of the chuck within opening 35 to release the rear end of `the chuck from this position. This force is required to overcome the resistance generated by the enlarged diameter of this chuck portion comparative to opening 35, and it represents the force necessary to deform this chuck portion sufficiently to penetrate the opening.

In use, a pipette or capillary tube S0 is positioned within the chuck bore 44 while the chuck 32 is in the forward position (i.e., that position depicted in FIG. 2). Since the chuck bore 44 is somewhat greater in diameter than the outside diameter of pipette 50, the pipette will shift easily into the chuck. The entire chuck is then shifted toward the rear of the holder so that the front portion 40 of the chuck shank is positioned within the barrel opening 35 (i.e., as depicted in FIG. 3). As was previously mentioned, in order for the chuck to assume this latter position, some deformation must occur and this deformation results in the inward displacement of portion 40 of the chuck shank which, in turn, results in the chuck securely engaging pipette 50 in an interfering fit. In other Words, when the chuck is in the rear position, the surfaces of the barrel defining opening 3S will bear down on the chuck sidewalls thereby uniformly reducing the diameter of bore 44 while, when the chuck is in the forward position, the diameter of bore 44 will be enlarged. The chuck may be shifted from the forward to the rear position by the application of uniform pressure to the forward face of flange 36.

With the pipette 50 securely positioned within the holder as described above, the technician may utilize the pipette-holder combination to draw any quantity of fluid into the pipette for transferring. For pipettes that fill completely by capillary action, all the technician need do to fill such a pipette is to immerse its tip in the donor vessel below the fiuid line and allow the pipette to fill. Where pipettes are used which do not fill by capillary action, aspiration may be necessary to fill the pipette. To this end, plunger rod 28 is utilized. In this regard, the technician would immerse the forward end of the pipette into the donor vessel and, with vent hole 26 open, the technician would lower the plunger rod 28 into the barrel interior. Since the vent hole is open, air displacement within the barrel caused by this lowering of the rod is compensated for through the vent hole and the fluid is uneffected. The technician would then cover vent hole 26 and simultaneously draw up plunger 28 by means of control loop or finger ring 30. By so doing, a partial vacuum is created within the barrel interior and fluid is drawn into the pipette to reduce the vacuum. The plunger 28 is withdrawn to the extent necessary to fill the pipette. In order to expel fluid from a filled pipette, the reverse procedure is followed, that is the technician will partially withdraw the plunger some distance from the forward end of the barrel with the Vent hole open and, then, covering the vent hole he would push the plunger into the barrel interior thereby creating a positive pressure within the barrel which serves to drive the fluid out of the tube. The pipettes contents may be emptied bringing it into contact with the donee vessel or material (absorbent paper, etc.), thereby inducing the fiuid within the pipette to flow. It should also be noted that in some instances it is desirable to eject the pipette with all its contents intact and this may be accomplished by pushing ejector rod 28 entirely in to the barrel without covering Vent hole 26.

After a fluid transfer has been completed, the pipette tip may be discarded and the holder used with a new pipette. To facilitate removal of spent pipettes, ejector or chuck release 34 is provided disposed within the barrely interior. Ejector 34 comprises a cylindrical member 'having a solid rear section 52 and bifurcated forward section. The prongs 54 and 56 of the forward section are spaced apart a sufficient distance so that when a pipette is positioned within the chuck 32, there will be no contact between the ejector and pipette. There is no need that the ejector 34 be secured to either the chuck 32 or rod 28 and may, in fact, be freely suspended within the barrel interior. The rear wall of ejector 34 includes a concave depression adapted to receive the forward portion of rod 28, as depicted in FIG. 3, and the forward ends of the ejector prongs rest on rear flange 38 of chuck 32. To eject a pipette all the technician need do is push down on gripping ring 30 while securing barrel 12. The downward force will be transmitted through rod 28 jto ejector 34 and then to chuck 32 causing the chuck to move forwardly thereby causing the enlargement of bore 44 as previously described.

The convex surface 60 of cylindrical wall 58 serves as a magnifying piece to magnify that portion of the pipette disposed within the ejector, as shown in FIG. 5. These magnifying pieces aid the technician in adequately filling the pipette and in minimizing overflling.

It should be understood that modifications may be made in the illustrated and described embodiment of our invention without departing from the invention as set forth in the accompanying claims.

We claim:

1. A pipette folder comprising: an elongated hollow barrel member having front and rear terminal portions; pipette gripping means slidably mounted in said front terminal portion and adapted to be shifted from a pipette gripping position to a release position; and variable air displacement means coupled to said barrel and adapted to remove air from or provide air to the barrel interior.

2. The pipette holder of claim 1 wherein said variable air displacement means includes an elongated rod shiftably mounted to said barrel extending into the barrel interior and vent hole extending through said barrel connecting the barrel interior to the outside.

3. The pipette holder in accordance with claim 2 wherein the length of said rod is substantially equal to the length of the barrel, the rod extends through the rear terminal portion of the barrel and the vent hole is positioned on the barrel proximal said rear terminal portion.

4. The holder in `accordance with claim 1 wherein said barrel front terminal portion has an opening of reduced diameter therethrough and said gripping means comprises an. elastomeric member disposed within said opening having one end interior the barrel, the opposite end exterior the barrel, a bore extending from end to end, and a shank portion disposed intermediate said ends, said shank including a rst portion the diameter of which is greater than the diameter of said front terminal portion opening and a second portion the diameter of which is smaller than the diameter of said front terminal portion opening.

5. The invention in accordance with claim 4 wherein said reduced diameter opening is shorter than the length of said first and said second shank portions, and said holder includes means for shifting said gripping means from a first position wherein said first shank portion is disposed within said opening to a second position wherein said second shank portion is disposed within said opening.

6. The invention in accordance with claim 5 wherein said holder further comprises an ejector disposed within said barrel and adapted to shift said gripping means from said first position to said second position when said elongated rod is shifted into the barrel interior beyond a predetermined position.

7. The invention in accordance with claim 6 wherein said ejector comprises an elongated member having a rear portion adapted to receive the forward end of said elongated rod, a front portion having surfaces to rest on the rear end of said gripping means, and a pipette receiving section dened by a void extending rearwardly from the front surface of said ejector, the dimensions of said void being such that when a pipette is in position within said gripping means, the sidewalls of said pipette are free from contact with the surfaces defining said void.

8. The invention in accordance with claim 7 wherein said ejector is a cylindrical member freely suspended within said holder and the forward portion of said ejector is bifurcated so as to produce two spaced apart prongs, the spacing between said prongs forming said pipette receiving void.

9. The invention in accordancewith claim 1 wherein said barrel is formed of transparent material and said holder further includes prefocused magnification means adapted to enlarge the rear end of a pipette when in position within said holder.

10. The invention in accordance with claim 9 wherein said magnification means comprise the spaced apart ejector prongs.

References Cited UNITED STATES PATENTS 8/ 1950 Lement. 8/1961 Demos 73-425.6 XR

U.S. C1. X.R. 23-259

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