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Publication numberUS3757585 A
Publication typeGrant
Publication dateSep 11, 1973
Filing dateSep 15, 1971
Priority dateMar 21, 1952
Also published asCA946337A1, CA954836A1, CA958383A1, CA966096A1, CA976929A1, CA1025821A1, DE1598123A1, DE1598123B2, DE1598124A1, DE1598124B2, DE1916515A1, DE1917491A1, DE1917491B2, DE1927773A1, DE1927773B2, DE1927773C3, DE1952774A1, DE1952774B2, DE1955807A1, DE2227731A1, DE2227731B2, DE2227731C3, DE2245413A1, DE2245413B2, DE2245413C3, DE2248573A1, DE2248573B2, DE2324681A1, DE2324681C2, DE2505431A1, DE6943120U, DE7236386U, US2724275, US3244009, US3494201, US3506164, US3525264, US3646817, US3741732, US3766784, US3766785, US3853012, USRE27637
Publication numberUS 3757585 A, US 3757585A, US-A-3757585, US3757585 A, US3757585A
InventorsS Hall, R Heller
Original AssigneeHeller Labor
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Pipette apparatus
US 3757585 A
Abstract
A manually-operated pipette for handling small volumes of liquid includes a spring-biased plunger and volume rod extending into a volume chamber. A spring-biased overriding slide sleeve is coupled to the plunger only during overriding ejection motion of the plunger, and switch means coupled to the sleeve provides electrical signalling of the ejecting motion. A removable universal disposable tip for pipettes of various maximum capacities communicates with the volume chamber of the body.
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Description  (OCR text may contain errors)

[451 Sept. 11, 1973 m W a W. S W

Waited Heller et al.

3,343,539 9/1967 Moorhouse.................... 3,498,135 3/1970 Seitz both of Santa Rosa Cahf' Primary Examiner-S. Clement Swisher [73] Assignee: Heller Laboratories, Santa Rosa, Attorney-A. C. Smith Calif.

[57] ABSTRACT A manually-operated pipette for handling small vol- 22 Filed: Sept. 15, 1971 [21] Appl. No.: 180,814

only during overriding ejection motion of the plunger,

[51] lint.

[58] Field of Search 73/4254 P, 425.6; and switch means coupled to the sleeve provides electrical signalling of the ejecting motion. A removable universal disposable tip for pipettes of various maximum capacities communicates with the volume chamber of the body.

[56] References Cited UNITED STATES PATENTS 73/425.6 4 Claims, 2 Drawing Figures LIQUID Patented Sept. 11, 1973 3,757,585

2 Sheets-Sheet l ||I U: t] E: 63 u I il/25 INVENTORS ROBERT E. HELLER STANLEY T. HALL Patented Sept. 11, 1973 2 Sheets-Sheet 2 INVENTORS ROBERT E. HELLER STANLEY T. HALL igure 2 IIWETTE APPARATUS BACKGROUND OF THE INVENTION generally performed in conventional pipettes at an inexact position of the ejection stroke, thereby creating inaccuracies in the timing of external events with respect to the complete ejection of a volume of liquid.

SUMMARY OF THE INVENTION In accordance with the illustrated embodiment of the present invention a spring-biased plunger protrudes from the body of a pipette for convenient manual actuation. A sliding volume rod attached to the plunger protrudes through a seal into a volume chamber within the body for altering the volume thereof to draw up or eject liquid in response to manual actuation of the plunger. A sleeve is slidably disposed within the body to engage the plunger only during final movement thereof in an ejection cycle and a switch is actuated by the sleeve to electrically signal external equipment at a preselected plunger position in the ejection cycle. A

' disposable tip with calibration marks to provide a visual cross check attaches to the body in communication with the volume chamber to contain a measured volume of liquid within the tapered internal bore of the tip.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of the pipette and disposable tip of the present invention in rest position at the start of an ejection cycle; and

FIG. 2 is a sectional view of the pipette and disposable tip of FIG. 1 showing the sleeve means actuated by the plunger during overriding ejection operation. FIG. 2 also shows means for actuation of electrical contacts.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is shown a generally cylindrical body 9 having diametrically opposed lateral extensions 11 protruding therefrom near the top portion of the body. These lateral extensions 11 serve as a convenient finger grip during operation of the pipette. Within the body 9 is a generally internal bore 13 which extends down from the upper end of the body 15 to a shoulder 17 at the base of the internal bore 13. A plunger 19 includes a volume rod 21 attached thereto which is disposed to move axiallywithin the internal bore 13 in response to manual pressure applied to the button or knob 23 attached to the upper end of the plunger 19. The body 9 connects to a volume cylinder 25 which is threaded into body 9 and which includes a volume chamber 27 into which protrudes the volume rod 21. Between the internal bore 13 and the volume chamber 27 within the body 9 and volume cylinder 25, there is disposed an O-ring seal 29 which slidably engages the outside diameter of the volume rod 21 to form an airtight or gastight seal between the body and the volume rod 21. The O-ring seal 29 also seals chambers 13 and 27 from each other and seals them from external atmosphere at the point of joining. Thus, in response to pressure manually applied to the button 23 of the plunger 19, the volume rod 21 is urged through the seal 29 into the volume chamber 27 to alter the volume therewithin and thereby to produce the air or gas displacing action of the pipette. This air or gas displacement will displace a like volume in pipette tip 51 which is joined to volume cylinder 25 in an airtight or gastight tapered seal. On the return, or intake stroke, the volume rod 21 is withdrawn from the volume chamber 27 to draw air or gas into the chamber 27 through the inlet 28. Therefore, if the pipette is held with the tip 51 down and placed into a liquid, said liquid will be drawn into disposable tip 51. However, the design is such that no liquid is drawn through inlet 28 and into volume chamber 27 or any other portion of the pipette. All liquid remains in the tip which is diposed of after the measurement is completed.

It has been found that the outside diameter of a rod such as volume rod 21 may be held to closer tolerances than the internal diameter of a cylindrical bore such as that within the volume chamber 27. For this reason, the volume rod is used as the calibrating device in this pipette, its diameter being a critical measurement. Thus, the internal dimensions of volume chamber 27 need not be critically maintained but need only provide adequate clearance to permit slidable movement of the volume rod 21 within the volume chamber 27 without unnecessary air space around the rod. Thus, with the 0-ring seal 29 slidably engaged about the diameter of volume rod 21, the air or gas displacement volume of the present pipette is accurately controlled in response to movement of the volume rod into the volume chamber 27. This air or gas displacement will displace a like volume of liquid in pipette tip 51 with an accuracy comparable to the calibration accuracy of the volume rod.

The plunger 19 and volume rod 21 are resiliently biased away from the shoulder 17 of the internal bore 13 by a first coil spring 31 which is positioned about the volume rod 21 within the internal bore 13. This spring 31, which bears against a shoulder 33 of the plunger 19, urges the plunger 19 into normal position outwardly protruding from the body 9 and biased against retainer plate 35. This plate is attached to the upper end of the body 9 by screws 34 and 36, and spans the laterally protruding elements 11 to protect the internal elements. Also contained within the internal bore 13 of the body 9 is a sleeve 37 which is disposed to slide axially within internal bore 13 and which is biased away from the shoulder 17 by a second spring 39. Thus, the springs 31 and 39 which bear against the shoulder 17 ofv internal bore 13 extend coaxially over a common portion of their lengths and serve to resiliently bias both the plunger 19 (and volume rod 21 attached thereto) and the sleeve 37. The coextension of springs over the common portion of their respective lengths thus reduces the over-all axial length of the pipette'of the present invention and thus facilitates ease of use and handling.

Referring now to FIG. 2, the plunger and volume rod 19, 21 are shown in position beyond the maximally depressed position and are shown in the ejection override position with the lower shoulder33 of plunger 19 engaged with the inwardly extending shoulder 41 carried by sleeve 37. It should be noted that, in this position, the plunger 1? is engaged with the sleeve 37 and manually applied pressure to the button 23 at the top end of plunger 19 must thus overcome the spring forces produced by both the spring 31 and the spring 39. This provides a measure of tactile feedback to the operator which indicates to him that the pipette has been operated beyond the calibrated range of displacement volume and is in the override or blowout portion of the ejection cycle. Thus, a calibrated volume of liquid is determined by movement of the plunger 19 and volume rod 21 (against the lightly spring-biased force provided by spring 31) from the rest position in which shoulder 33 of plunger 19 rests on the retainer plate 35 to the position at which the shoulder 33 on plunger 19 engages shoulder 41 on sleeve 37. The abrupt increase in the required force to depress sleeve 37 with plunger 19 thus provides a positive-feeling indication of the completion of the calibrated portion of the ejection cycle and alerts the operator to the initiation of the blowout" cycle which permits the volume rod 21 to override its spring-biased stop position (provided by sleeve 37) and carry both the plunger 19, volume rod 21 and sleeve 37 into the override or blowout" portion of the ejection cycle. This overriding motion of the volume rod 21 assures complete ejection of liquid drawn up into the volume pipette tip 51 during the intake cycle of operation of the plunger.

The overriding motion during the ejection cycle causes sleeve 37 to actuate switch 43 contained within one of the lateral extensions 11 of the body 9. This switch may contain a pair of resilient metal spring leaves which are spaced apart out of electrical contact during normal position of the sleeve 37 against the retainer plate 35. One spring leaf 45 is positioned to be actuated by the sliding movement of the sleeve 37, thereby to contact the other spring leaf 47 of the switch means 43. Electrical connections to suitable external circuitry such as timer, mixers, heaters, coolers, or the like may be made through conventional electrical jack connector 49 which connects to the spring leaves 45 and 47 as shown. Thus, the switch means 43 arranged within the body 9 of the present pipette is actuated only in response to overriding movement of the sleeve during the uncalibrated blowout portion of the ejection cycle, which occurs only after completion of the calibrated ejection cycle. This assures that electrical signalling of external circuitry may be performed only during the ejection cycle and only upon complete expulsion of the calibrated volume of liquid. This eliminates the possibilities of premature electrical signalling of external circuitry as the liquid is being drawn up or during the ejection cycle when only a portion of the liquid being handled has been ejected, a problem commonly encountered in conventional pipettes.

The pipette system for liquid-handling includes both the volume chamber 27 located within the lower body portion 25 and a disposable tip 51 attached thereto. In order to avoid contamination of the volume chamber of the pipette, it is common practice to handle the liquid entirely within the disposable tip 51. For this reason, the tip 51 may be conveniently formed inexpensively of a suitable material such as a translucent plastic. The tip 51 includes an orifice 53 at its distal end remotely from the connector port or attachment end 55 and includes a tapered internal bore 57 through the tip which communicates with both the orifice 53 and the connector port 55. The internal bore 57 is formed at two taper angles over the length of the tip. The first taper angle 59 adjacent the orifice 53 may be of the order of five degrees and extends over approximately forty to fifty percent of the length of the tip 51. The second taper angle 61 extends over the remaining portion of the length of the tip 51 and is of smaller angle (typically one and one-half degrees) than the first taper angle 59. The tip 51 constructed in this manner may thus serve as a universal, disposable tip capable of handling a wide range of liquid volumes. In addition, the external surface of the tip 51 includes volumetric graduations 63 disposed at selected locations away from the orifice 53. These volumetric graduations may be in the form of abrupt transitions in the external diameter of the tip or may be gouged or scored or otherwise marked into the outside surface of the tip 51. These volumetric graduations may thus provide a continuing visual cross check on the accuracy of the pipette of the present invention.

The maximum volumetric capacity of these pipettes may be altered conveniently simply by altering the diameter and/or length of stroke of the volume rod 21, the associated O-ring seal 29, and the volume chamber 27 within the volume cylinder 25. Pipettes of smaller maximum capacity may thus have volume cylinders of smaller external diameter. Specifically, the external diameter and length of the end of the volume cylinder 25 is selected to protrude into the tapered internal bore 57 of tip 51 to a position slightly above volumetric graduation 63 which represents the calibrated volume of the pipette attached to the tip. This enhances the universal application of the same tip design for use with a wide range of pipettes of widely varying maximum capacities. For each size of pipette, the end of the volume cylinder 25 thus press fits into the tapered bore 57 of the tip at a position approximately one-half division above its appropriate volumetric graduation. Each volumetric graduation indicates the actual maximum capacity of the volume chamber and volume rod 21, 27 of the appropriate size pipette. This provides a visual cross check on the accuracy of the pipette since the maximum capacity of calibrated volume should correspond with the next volumetric graduation visible beyond the end of the volume cylinder 25 positioned within the internal bore 57. This significantly reduces the excess air volume within the liquid-carrying chamber, prevents meniscus bounce and thereby preserves the accuracy of the calibrated liquid-handling capacity. A complete line of pipettes of different maximum capacities, having color-coded markings on band 30 and plunger buttons 23, may thus be used with one size of tip 51 of the present invention. Other pipettes usually use several sizes of tip to accommodate different-sized pipettes and to avoid the cushioning problem caused by measuring a small volume of liquid within a relatively large pipette tip.

We claim:

1. Pipetting apparatus comprising:

a body including an internal bore therein having a shoulder located at a selected depth within the internal bore, the body having a narrowing portion comprising a volume cylinder which is hollowed to fonn a volume chamber which is axially spaced away from said body internal bore and which communicates with said internal bore through an axially aligned aperture within the body;

sleeve means mounted within said body for slidable movement therewithin in a direction substantially along the axis of said internal bore;

a plunger including a volume rod attached thereto mounted within said body for slidable movement therewithin with said plunger slidably movable within said internal bore and with said volume rod protruding through said aperture into said volume chamber;

coupling means between said plunger and said sleeve means for engaging the sleeve means to slide with said plunger within said body only over a preselected nearer portion of the slidable movement of the plunger which is near the shoulder of the internal bore and for disengaging the sleeve means from said plunger over a remaining portion of the slidable movement of said plunger which is remote from said shoulder;

first spring means disposed within said body for resiliently biasing said plunger away from said shoulder;

second spring means disposed within said body to resiliently bias said sleeve means with respect to said body for yieldably maintaining said sleeve means in fixed position of disengagement from the plunger during said remaining remote portion of slidable movement thereof; and

electrical switch means disposed within said body to be actuated in response to sliding movement of said sleeve means with said plunger during said preselected nearer portion of the movement thereof.

2. Pipetting apparatus as in claim 1 wherein:

said plunger includes a manually-actuatable push rod coupled thereto to protrude from the end of said body remote from said shoulder in substantially coaxial alignment with said plunger; 1

said body includes substantially diametrically opposed, laterally extending portions near the end of the body from which said push rod protrudes; and

said switch means is supported within a laterally extending portion of the body to be actuated by sliding movement of said sleeve means within said internal bore of the body.

3. Pipetting apparatus comprising:

a body including an internal bore therein having a shoulder located at a selected depth within the internal bore, the body having a narrowing portion comprising a volume cylinder which is hollowed to form a volume chamber which is axially spaced away from said body internal bore and which communicates with said internal bore through an axially aligned aperture within the body; v

sleeve means mounted within said body for slidable movement therewithin in a direction substantially along the axis of said internal bore;

a plunger including a volume rod attached thereto mounted within said body for slidable movement therewithin with said plunger slidably movable within said internal bore and with said volume rod protruding through said aperture into said volume chamber;

coupling means between said plunger and said sleeve means for engaging the sleeve means to slide with said plunger within said body only over a preselected nearer portion of the slidable movement of the plunger which is near the shoulder of the internal bore and for disengaging the sleeve means from said plunger over a remaining portion of the slidable movement of said plunger which is remote from said shoulder;

first spring means disposed within said body for resiliently biasing said plunger away from said shoulder;

second spring means disposed within said body to resiliently bias said sleeve means with respect to said body for yieldably maintaining said sleeve means in fixed position of disengagement from the plunger during said remaining remote portion of slidable movement thereof;

a liquid-holding tip for said apparatus having a tapered internal bore which communicates with an orifice at the narrow end of the tip and with a connection port at the wide end within which the distal end of the volume cylinder is inserted;

said tip includes volumetric graduations thereon for visually measuring a volume of liquid within the region of the internal tapered bore thereof adjacent said orifice; and

the extreme outside lateral dimension of the volume cylinder near the distal end thereof corresponds with the internal dimension of the tapered bore in said tip for sealingly engaging the internal tapered bore of said tip above and proximate the volumetric graduation that is representative of said volume rod protruding into said volume chamber by the amount of the calibrated portion of slidable movement of said plunger.

4. A universal liquid-holding tip adapted to attach to the inlet and discharge ends of pipetting apparatus having end diameters that are representative of the maximum capacities of the pipetting apparatus, the tip comprising:

an elongated vessel having an internal bore which communicates with and diverges from an orifice at the narrow end of the vessel and which also communicates with a connection port at the wide end of the vessel, said elongated vessel having volumetric graduations thereon from the orifice end thereof corresponding substantially to the maximum capacities of pipetting apparatus to be associated therewith; and

the divergence of the internal bore providing sealing engagement with the end of associated pipetting apparatus at adepth within the internal bore that substantially corresponds with a volumetric graduation for a liquid volume in the region adjacent the orifice which is not less than the maximum capacity of the associated pipetting apparatus.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3343539 *Oct 22, 1964Sep 26, 1967Moorhouse Turkey Hatchery IncPiston type artificial insemination syringe having stroke adjusting means
US3494201 *Aug 16, 1968Feb 10, 1970Oxford LabPipetting system
US3498135 *Nov 13, 1968Mar 3, 1970Baxter Laboratories IncPipette
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3873274 *Feb 2, 1973Mar 25, 1975Merck Patent GmbhTitrator
US4347875 *Jul 14, 1980Sep 7, 1982Eastman Kodak CompanySelf-cleaning nozzle construction for aspirators
US4442722 *Jan 7, 1983Apr 17, 1984Beckman Instruments Inc.Plunger operated pipet
US4489618 *Feb 23, 1982Dec 25, 1984Meyer Richard CPipet signalling system
US4567780 *Mar 12, 1984Feb 4, 1986American Hospital Supply CorporationHand-held pipette with disposable capillary
US5315886 *Nov 1, 1991May 31, 1994Jean GuiganApparatus for drawing off and dispensing a predetermined quantity of a liquid
US5355738 *Jan 9, 1992Oct 18, 1994Labsystems OyPositive-displacement pipette
US6066297 *Jan 3, 1997May 23, 2000Matrix Technologies CorporationSmall sample volume displacement pipette tips
US8114362 *Oct 4, 2005Feb 14, 2012Vistalab Technologies, Inc.Automatic pipette identification
US8163153 *Dec 20, 2005Apr 24, 2012Caldwell Jeremy STool for extracting electrophoretic sample
US8524170 *Feb 22, 2011Sep 3, 2013Rainin Instrument, LlcPipette and sealing tip
US20120213677 *Feb 22, 2011Aug 23, 2012Rainin Instrument, LlcPipette and sealing tip
EP0691158A2 *Jun 6, 1995Jan 10, 1996Brand GmbH + CoPipetting system
Classifications
U.S. Classification73/864.18, 422/931
International ClassificationB01L9/00, A47G23/02, A61M1/00, G01F11/06, A61M5/315, A61M5/34, C01B17/90, G01N33/483, G01N1/00, G01N33/487, B01L3/02, B01L9/06, A61B5/15, A61B5/145, G01N33/49
Cooperative ClassificationA61M5/315, B01L3/0279, A61B5/150022, A61B5/150213, A61B5/1411, A61B5/14, A61M1/00, B01L9/06, B01L9/543, A61B5/150343, B01L3/0241, A61B5/150244, B01L3/021, B01L3/0275, B01L2200/04, A61B5/150099, B01L3/0224, B01L3/0217, A61B5/150259, A61B5/150236, A61M5/346, C01B17/907, B01L2300/0838, B01L3/0213, A61M5/31531, B01L3/0231, A61M5/344, A61M5/347, B01L3/0282
European ClassificationB01L3/02C1, B01L9/543, A61B5/15B8H, A61B5/15B8J, A61B5/15B8N, A61B5/15B8B, A61B5/15B10, A61B5/15B4B10, A61B5/15B2B, A61M5/34C, B01L3/02E, B01L3/02C3, C01B17/90K, B01L3/02F, B01L3/02C3D, B01L9/06, A61M1/00, A61B5/14, A61M5/315, A61B5/14B2, B01L3/02C, B01L3/02C3P, B01L3/02E2, B01L3/02D