US 3739821 A
A pipette including an elongated tubular body open at both ends and having as a fixed part thereof a radial flange structure intermediate of its ends by which flange structure the body is suspended from the mouth of a vessel in the central region thereof in operative position to aspirate the liquid contents of the vessel. This is the normal or storage position of the pipette which includes in the flange structure a portion lying in a plane normal to that of the body and which in the last-mentioned position overlies the mouth of the vessel in proximity thereto and extends laterally beyond it. The flange structure also includes a fixed skirt portion suspended from the first named portion in rigid relation thereto and which, in the last-mentioned position of the pipette, embraces the mouth portion of the vessel telescoped therein. A lower marginal portion of the skirt is tapered interiorly to coact with the mouth of the vessel when the pipette is dropped into the vessel, effectively centering and guiding the pipette toward its normal position from a raised position. The flange structure also has a part thereof which coacts with the mouth of the vessel, in the stored position of the pipette, and which forms an air passageway from the vessel only from beneath the skirt portion.
Claims available in
Description (OCR text may contain errors)
United States Patent Watkin et al.
MACHINE-TRANSFERRABLE PIPETTE Inventors: Theodore Watkin, Stamford, Conn.;
Donald F. Wiseman, Wayne, NJ.
 Assignee: Technicou Instruments Corporation,
Tarrytown, NY. Filed: Apr, 26, 1971 Appl. No.: 137,385
[5 6] References Cited UNITED STATES PATENTS 21195 0 Stovall 128/233 12/1912 Scho0p..... 222/204 X 11/1937 Moran 73/4254 P 9/1971 Beer 73/425.6
6/1969 Norwood 141/392 2/1901 Clavez", 141/374 X Primary Examinen-Sarnuel F. Coleman Assistant Examiner -Thomas E. Kocovsky Attorney-Tedesco & Rockwell June 19, 1973  ABSTRACT A pipette including an elongated tubular body open at both ends and having as a fixed part thereof a radial flange structure intermediate of its ends by which flange structure the body is suspended from the mouth of a vessel in the central region thereof in operative position to aspirate the liquid contents of the vessel. This is the normal or storage position of the pipette which includes in the flange structure a portion lying in a plane normal tothat of the body and which in the lastmentioned position overlies the mouth of the vessel in proximity thereto and extends laterally beyond it. The flange structure also includes a fixed skirt portion suspended from the first named portion in rigid relation thereto and which, in the last-mentioned position of the pipette, embraces the mouth portion of the vessel telescoped therein. A lower marginal portion of the skirt is tapered interiorly to coact with the mouth of the vessel when the pipette is dropped into the vessel, effectively centering and guiding the pipette toward its normal position from a raised position. The flange structure also has a part thereof which coacts with the mouth of the vessel, in the stored position of the pipette, and which forms an air passageway from the vessel only from beneath the skirt portion.
6 Claims, 4 Drawing Figures 1 MACHINE-TRANSFERRABLE PIPETTE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a pipette useful in chemical and biochemical research or clinical laboratories for transferring a measured quantity of one liquid from one vessel to another vessel or vessels, usually for a reaction of the liquid with another liquid.
2. Prior Art In laboratories such as characterized above it is common in carrying out biochemical analyses of various types to employ test tubes, cuvettes or flasks for the storage, usually on a temporary basis, ofliquid substances, or substances in liquid carriers, used in such analysis. Such vessels containing such substances are often capped prior to removal of a portion of the contents, as by a pipette, and recapped after such removal. Such caps effectively tend to prevent foreign substances from falling into the vessels and contaminating the contents thereof. They have provided gas vents for the contents of such vessels to maintain the gas pressure in the vessels, commonly constructed of glass, substantially equal to atmospheric pressure. At least to a large extent, such caps have reduced spillage of the vessel contents during handling of the vessel, and have also reduced the risk of contamination of the ambient atmosphere by the vessel contents.
As previously indicated, to our knowledge, such caps have been so constructed as to require removal prior to transfer by pipette of contents of one vessel to another often requiring recapping. This process of liquid transfer includes entry of a pipette, often constructed of glass, into the uncapped vessel, loading of thepipette by aspiration, removal of the pipette from the vessel, and recapping the vessel. It also requires after use, manual disposition of the pipette as by placement thereof on a supporting table surface or in a trash receptacle if the pipette is of a disposable type. Obviously, thereexists during sucha process, in addition to the disadvantageous number of steps required, a risk of breakage of the elements occasioned by mishandling or collisions, and the risks of spillage and contamination. It will also be obvious from the foregoing that if a conventional pipette is left in an uncapped vessel, it will be supported by its tip from the bottom of the vessel and the body of the pipettewill be supported from one side of he vessel mouth where it comes to rest by gravity. In other words, it will lean at an angle to the vertical in and against the vessel.
SUMMARY OF THE INVENTION I It is an object of the invention to provide in a unitary structure a combined vessel cap and pipette, which. structure supports the pipette from the vessel mouth in a centered and vertical position for manual or machine pickup, in which position liquid in the vessel may be aspirated into the pipette. Further objects will be apparent from the following detailed description.
In accordance with the invention there is provided a pipette including an elongated tubular body open at both ends and having as a fixed part thereof a radial flange structure intermediate of its ends by which flange structure the body is suspended from the mouth of a vessel in the central region thereof in operative position to aspirate the liquid contents of the vessel. This is the normal or storage position of the pipette which includes in the flange structure a disc portion lying in a plane normal to that of the body and which, in the last-mentioned position of the body, overlies the mouth of the vessel in proximity thereto and extends laterally beyond it. The flange structure also includes a fixed skirt portion suspended from the first-named portion in rigid relation thereto in which, in the last-mentioned position of the pipette, embraces the mouth portion of the vessel which mouth portion is telescoped therein. A lower marginal portion of the skirt is tapered interiorly to coact with the mouth of the vessel when the pipette is dropped into the vessel, effectively centering and guiding the pipette toward its normal position from a raised position. The flange structure also has a part thereof which coacts with the mouth of the vessel, in the stored position of the pipette, and which forms a gas passageway from the vessel only from beneath the skirt portion.
BRIEF DESCRIPTION OF THE DRAWING In the drawing:
FIG. 1 is a perspective view of a the invention;
FIG. 2 is a longitudinal median sectional view of the pipette illustrating the latter resting in a vessel such as a test tube or cuvette;
FIG. 3 is a fragmentary view illustrating in elevation, somewhat diagrammatically and in part in section, the machine pickup and delivery of the liquid from the container of FIG. 2 to another vessel, employing the pipette; and I FIG. 4 is a view similar to FIG. 3, illustrating the return of the pipette to the container or vessel of FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS In the drawing, the pipette is indicated generally at 10. It has an elongated tubular body 11 having a some what narrowed and pointed lower end portion in which there is provided a liquid inlet and outlet 12 as shown in FIG. 2. The other end of the body is open, as at 13, and the body may be formed conveniently of glass or may be formed of a plastic material such as clear polystyrene. It is preferably that the pipette be formed of transparent material.
The usual pipette graduations (not shown) may be provided on the pipette body arranged lengthwise thereof. Such graduations may indicate the volume of liquid in the pipette which is aspirated thereinto through the opening 12 and may also indicate the volume dispensed from the pipette through the opening 12. Liquid may be aspirated into the body 11 through suction by the mouth of the user to the upper end and opening 13 or may be applied by a machine in a manner to be described hereinafter. If suction is applied orally to the tube 11 to convey liquid from a vessel, such as that shown in FIG. 2, into the pipette to the desired level, the user thereafter places a finger on the open upper end of the pipette to maintain the liquid captive in the tube 11. The liquid is dispensed by removing the users finger from the opening 13, permitting air to pass thereinto and causing discharge through the opening 12.
The liquid vessel shown in FIG. 2 and indicated at 14 is illustrated only for purposes of example as being a test tube or the like having a rounded closed lower end and an open upper end. It has a cylindrical upper wall pipette embodying structure of uniform cross section, as at 16. That is, its outer diameter is uniform in this area. The lower portion of the vessel 14 may be structured as a flask, if desired, rather than as a tube. The vessel 14 may be structured of lime glass for example or it may be formed of a suitable plastic material.
Intermediate the ends of the pipette body 11 the pipette is provided with a fixed radial flange structure indicated generally at 18. The flange structure is preferably formed as an integral part of the body 11 as by being molded therewith. The structure 18 includes a portion 20 in the form of a'disc extending radially outwardly from the body 1 l and lying in a plane normal to the plane of the body 11. The structure 18 also includes a skirt portion 22 suspended from the outer marginal portion of the disc portion 20 and of a vertical or longitudinal dimension approximating three times the outer diameter of the main portion of the body 11.
The upper part of the skirt portion 18 is circular as shown best in FIGS. 1 and 2, and the lower part thereof is flared, as at 24, and provided with a thickened part 26 at the lower extremity of the skirt to provide added strength in this region. The inner surface 28 of the flared part 24 is generated as a truncated cone, tapering upwardly and toward the axis of the pipette body 1 l. The vertical dimension of the surface 28 is approximately one-third the height of the skirt portion 22 and merges with the cylindrical inner surface thereof in the illustrated form of the pipette. The angle of the surface 28 to the vertical may be approximately 30.
When the pipette is lowered or dropped into the receptacle 14, when not substantially aligned with the axis thereof, the aforementioned surface 28, which may be considered a cam surface, coacts with the periphery of the edge 30 defining the mouth of the vessel 14 in a manner to effectively center and guide the pipette toward a substantially central position similar to that shown in FIG. 2. The flange structure 18 of the pipette is shown in FIG. 2 as supporting the pipette in suspended and spaced relation from the bottom of the vesse] 14, and the flange structure is in turn supported from the mouth of the vessel 14. In this position, the mouth or neck portion of the vessel is telescoped within the skirt portion 22.
It is desired that the cap structure for the vessel 14 permit equilization of gas pressure within the vessel 14 and the ambient atmosphere. For this purpose an air or gas passageway is formed between the cap 18 and the mouth of the vessel for such gas as might build up in the vessel 14 to be vented beneath the skirt provided by the cap 18. To this end the undersurface of the disc portion 20 of the cap may have shoulders, gussets or grooves or, as in the illustrated form, it may be ribbed to provide gas passages between the interior of the vessel and the interior of the skirt portion 22. Four ribs 32, circumferentially spaced apart and extending in radial directions, are formed on the underside of the disc portion 20, which ribs 32 rest on the mouth of the vessel 14 to provide therebetween the aforementioned gas passages. By way of example, the inner diameter of the upper cylindrical portion of the skirt may be approximately 0.687 inch, while the inner diameter of the skirt at its lowest extremity may be 0.988 inch. The outer diameter of the major portion of the tube 11 may be 0.375 inch. The inner diameter of the neck of the vessel 14 may be 0.557 inch and the outer diameter of the neck of the vessel may be 0.620 inch.
As shown in FIG. 2, a wad 34 of cotton or the like may be inserted in the upper end portion of the tubular body 11 to facilitate maintaining the contents of the vessel 14 free from contamination by foreign objects which might otherwise fall thereinto through the pipette body 11 and which wad of material also tends to maintain the contents of the vessel 14 captive. The wad 34 may remain in the pipette while liquid is aspirated thereinto and discharged therefrom. If desired a device or element may extend into the upper end portionof the pipette body 11 below the wad 34 to prevent dislocation of the latter downwardly in the body 11. Also, the upper end of'the body 11 may be tapered somewhat, as at 36, to facilitate the insertion of this end of the pipette into a machine element for picking up the pipette while retaining sufficient material at this end of the pipette to enable the pipette to be knocked out of the machine element at the desired point, without breakage of the pipette by impingement on this end of the pipette. The machine pickup of the pipette is illustrated and described in detail in the copending patent application, assigned to the same assignee, of Henry D. Isenberg et al. Ser. No. 139,435, filed May 3, 1971, titled Method and Apparatus for Automated Antibiotic Susceptibility Analysis of Bacteria Samples.
As shown in FIGS. 3 and 4, the pipette may be picked up from the vessel 14 by a machine element, moved laterally and subsequently returned to the vessel 14 by the machine element. As will be more apparent hereinafter, the pipette may be picked up from the vessel 14 by the machine element for transfer and deposit of the pipette in another vessel (not shown) if desired. The machine element in the form of a pipette holder is indicated generally at 38. The holder 38 may comprise an elongated body 40 having a bore 42 extending therethrough in a vertical direction as shown in FIG. 3. The bore 42 is counterbored, as at 44. I
An end cap extends over the outer end of the counterbore 44 and this cap is provided with a tapered orifice 46 through which the upper end portion of the body 11 of the pipette is extensible. Through the upper end of the bore 42 there extends a plunger 48 axially moveable in the bore 42 but provided with air-tight sealing devices or rings 50.
At least two O-rings are provided in the counterbore 44 in axially spaced-apart relationship to form an airtight seal around the upper end portion of the pipette when it is inserted in the holder, and to prevent the pipette from cocking in the holder from the vertical position. The O-rings 52 are so constructed and arranged that when they are engaged and seal against the pipette they do not engage so as to be compressed against the wall of the counterbore 44 but rather have clearance with the last-mentioned wall. This tends very effectively to reduce friction when the pipette is extended into the O-rings 52 or removed therefrom. In fact, in the construction shown, at least the lowermost O-ring 52 tends to have only line contact with the pipette when it is inserted in the holder and line contact with the aforementioned cap of the holder.
A ring-like spacer 54 is interposed between the 0- rings 52 and has cam surfaces thereon engageable with the respective O-rings tending to center them. A light compression spring 56 has one end thereof bottoming in the counterbore 44 and has the other end thereof bearing against a sleeve 57 bearing against the upper surface of the uppermost one of the O-rings 52. This spring and the spring follower 57, together with the ring 54, tend to maintain the O-rings 52 in their proper relationship to receive the upper end of the pipette within the holder.
The holder has an air port 58 extending into the body 40 in communication with the bore 42, which port 58 may have an air conduit 60 associated therewith, if desired, extending in a direction away from the holder body 40; but, in any event, the port 58 is controlled by a shut-off valve not shown.
As shown in FIGS. 3 and 4 the vessel 14, with the pipette supported in it in the aforementioned manner, is supported in vertical position by a support element 62 having a socket through which it extends and a complementary support element 64 having a socket to receive the lower end of the vessel 14. The arrangement is such that the vessel 14 with the pipette extending thereinto may be dropped into the support 62, 64 and lifted therefrom when desired. The support provided by the elements 62 and 64 may be stationary or, if desired, may be formed as part of a turntable.
Only one other vessel, indicated at 66, is illustrated I as being provided for receipt of liquid from the pipette delivered from the vessel 14. It will be appreciated that contents from the pipette may be discharged into more than one vessel. The vessel 66 while illustrated as similar to the vessel 14 may have a different shape, its only requirement being that it have an upwardly directed open mouth. The vessel 66 is shown supported by support elements 68 and 70 similar to the above described support elements 62 and 64, respectively.
A suitable mechanism, not shown, is provided for lowering and raising the holder 38 and traversing it laterally as indicated in the dashed lines in FIGS. 3 and 4. In its movements the holder 38 is first aligned with the station at which the vessel 14 is supported with the pipette extending thereinto and supported by the vessel in the manner shown in FIG. 2. The holder is then caused to descend a distance sufficiently for the upper end portion of the pipette body 11 to enter into the holder and be received therein in sealing engagement in the manner shown in FIG. 3. It will be noted that the holder does not descend a distance sufficiently to impact with the flange structure or cap 18 which impact might effect breakage of the pipette 10 or the vessel 14. While the holder 38 is in the position shown in FIG. 3 and the valve controlling the air port 58 is closed, the plunger 48 is raised to aspirate fluid from the vessel 14 into the pipette,'the amount of liquid so aspirated being dependent on the distance of travel of the plunger 48 before it is stopped. A suitable mechanism, not shown, is provided to effect axial movement of the plunger 48 in both directions when desired. The holder 38 is then raised a distance sufficient for the pipette to clear the vessel 14. Subsequently the holder 38 is traversed to a position in which the lower end of the pipette 10 is disposed over and a distance above the mouth of the vessel 66 as shown in broken lines of FIG. 3. Then, by opening the valve controlling the air port 58, so as to admit air under atmospheric pressure to the bore 42 and the opening 13 in the upper end of the pipette, liquid may be discharged through the opening 12 in the pipette to fall by gravity into the vessel 66, and this discharge may continue until the valve controlling the air port 58 is closed.
. The return travel of the pipette toward the vessel 14 is shown in FIG. 4. The holder is traversed to the position shown in the last-mentioned view in which the pipette is over and spaced above the vessel 14. The holder 38 is then lowered from the position of FIG. 4 so that the lower end of the pipette is moved well into the vessel 14, and while the cap 18 is spaced above the mouth of the vessel 14 the plunger 48 is caused to de scend, first effecting the complete evacuation of liquid from the pipette 10 into the receptacle 14 by air pressure, and then striking the upper end of the body 11 of the pipette and causing the pipette to be ejected from the holder 38. The pipette then falls by gravity into the vessel 14 with the cap structure 18 providing the necessary camming action through the surface 28 thereof as aforesaid to guide and center the pipette with reference to the vessel 14 through coaction of. the surface 28 and the mouth of the vessel. It will be appreciated from the foregoing that the so-called camming action of the cap 18 on the vessel compensates for any misalignment within practical limits of the holder 38 with reference to the vessel support elements 62 and 64 and also compensates for any misalignment within practical limits of the vessel 14 in the support element 62 and 64.
It will be evident from the foregoing, that if the pipette is used manually for the transfer of liquid from the vessel 14 to another vessel, the user may grasp and manipulate the vessel 14 with the thumb and forefinger of one hand, while manipulating the pipette by the flange structure 18 in the grasp of thumb and forefinger of the other hand of the user. The users hands need not touch the body 11 while the pipette is in use, which is a distinct advantage.
While several forms of the pipette have been described together with various uses, it will be appreciated by those versed in the art that the pipette may take other forms and it is susceptible of various changes in details and uses without departing from the principles of the invention.
What is claimed is:
l. A machine-transferable pipette for transferring a sample from one vessel to another and return to the first vessel to be dropped so as to have a free fall therein, said first vessel having a neck portion providing an upwardly opening mouth, comprising: an elongated tubular body adapted to be arranged vertically having an inlet and discharge opening in the lower end portion thereof and a suction opening in the upper portion thereof, said upper portion being free for pickup of the pipette, and a flange portion comprising a disc part embracing and fixed to the body intermediate said discharge and suction openings, said flange portion having pipette-guiding and-centering means comprising a relatively rigid skirt fixed to and depending from the outer margin of said disc, said skirt having an inner transverse dimension greater than the neck of said first vessel, said skirt being sufficiently smooth to slide over said vessel neck and terminating downwardly in a free edge, and said skirt having an inner surface portion extending upwardly a distance in a direction from said free edge and inclined toward the axis of said body so as to slidingly coact with said mouth of said first vessel, when the pipette is dropped in said first vessel as aforesaid, said neck of the vessel telescoping within said skirt, said disc being engageable with said mouth of said first vessel and serving to suspend said body in the lastmentioned vessel in the normal position of said body; said flange portion having means thereon coactin'g with said first vessel to form a passageway from the interior 7 8 of the vessel to the ambient atmosphere from beneath 5. A pipette as defined in claim 1 wherein, saidskirt said skirt. is formed integrally with said disc part and the latter is 2. A pipette as defined in claim 1 wherein, said flange formed integrally with said body. portion, together with said skirt thereof, is imperforate. 6. A pipette as defined in claim wherein, said disc 3. A pipette as defined in claim 1 wherein, said free 5 part has means thereon coacting with said vessel mouth edge of said skirt is formed as a flared part thereof. to form a gas passageway from the interior of the vessel 4. A pipette as defined in claim 1 wherein, said inner to the ambient atmosphere from beneath said skirt. surface portion of said skirt extends to said free edge.