CA1192876A - Mechanically actuated pipette dispenser - Google Patents
Mechanically actuated pipette dispenserInfo
- Publication number
- CA1192876A CA1192876A CA000409399A CA409399A CA1192876A CA 1192876 A CA1192876 A CA 1192876A CA 000409399 A CA000409399 A CA 000409399A CA 409399 A CA409399 A CA 409399A CA 1192876 A CA1192876 A CA 1192876A
- Authority
- CA
- Canada
- Prior art keywords
- pipette
- piston
- chamber
- actuating means
- actuation arm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
- B01L3/02—Burettes; Pipettes
- B01L3/021—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
- B01L3/0217—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type
- B01L3/0234—Repeating pipettes, i.e. for dispensing multiple doses from a single charge
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L9/00—Supporting devices; Holding devices
- B01L9/54—Supports specially adapted for pipettes and burettes
Abstract
MECHANICALLY ACTUATED PIPETTE DISPENSER
Abstract A liquid dispenser is disclosed, comprising a vented pipette and an actuator for the pipette. The actuator includes means for mounting the pipette and means for automatically lowering a piston into the pipette to a predetermined starting level before the pipette vent is sealed, to insure that a predictable quantity of liquid is dispensed once the vent is sealed.
Abstract A liquid dispenser is disclosed, comprising a vented pipette and an actuator for the pipette. The actuator includes means for mounting the pipette and means for automatically lowering a piston into the pipette to a predetermined starting level before the pipette vent is sealed, to insure that a predictable quantity of liquid is dispensed once the vent is sealed.
Description
MECHAN:tCALLY ACTUATED PIPETTE DISPENSER
Field oE the Invention This invention relates to apparatus and a pro-cess for dispensing liquids, such as biological liquids, for chemical analysis.
BACKGROUND OF THE INVENTION
Mechanical actuating means, hereinafter "act-uators", have been used prior to this invention to removably mount and to actuate vented pipettes ~o that the contents are dispensed~ By the push of a lever or a button, a ratchet is advanced in steps to cause a piston or plunger of the pipette to repeatedly dispense a pre determined, Eixed ~mount of liquid. The advantage of such a mechanism is that it reduces the opportunity for the errors that oten occur when pipettes are operated manually. When a new pipette is filled for dispensing, the previously emptied pipette is removed and the new one mounted in the ac~uator. Examples of such devices are described in U.S. Paten~ No. 3,161,323.
One difficulty with such mechanical actuators is that, unless prohibi~ively expensive pipette designs are used, the piston of the pipette is not reliably at a predetermined height as to accurately line up with the driving surface of the actuator. Because of this, either the actuator or the pipette must be adju~ted by less than a whole s~ep to bring the actuator's driving surface into contact with the pis~on of the pipet~e, a process hereinafter referred to as "initializing.~' How-ever, initializing by altering the location of the driv-ing surface is generally not desirable. It is particu-larly unsatisfactory when the actuator is programmed to operate in fixed steps only, as noted. If the pipette piston's initial location should be between one of the fixed levels defining the steps, the driving surface wo~ld have to be moved downward or upward during ini-tializing by less than a whole step. Such movement would alter the volume of the first quantity to be dis~
pensed.
On the other hand, initializing by adjustirg the pipette and particularly ~he piston of the pipette has not been desirable prior to this invention. At best, manually readjusting the pipette to ob~ain contact with ~he driving surface i~ time consuming. At worst, such adjustment might requlre that the pis~on be lowered to the level of the driving surface. If the vent of the pipette accidentally becomes closed while the piston is being so lowered, undesired liquid dispensing occurs.
Since the pipette vent is conveniently an aperture through the top o the piston at the very place force is normally applied to depress ~he piston, it has been dif ficult to downwardly adjus~ the pis~on without closing the vent.
Because of the above problems, use of mechani-cal actuators of pipettes has been less than ~atisfac-tory. Particularly the initializing problem has been acute when many individual pipettes are to be sequen-tially inserted into the actuator, each with a poten-tially different ini~ial piston location.
Therefore, what has been needed is a mechanical actuator for a pipet~e and par~icularly a vented pipette~ which automatically orients the piston and actuator driving surface wi~hout any loss of the liquid contained in the pipette.
SUMMARY OF THE INYENTION
The invention is directed to appara~us and a process for dispensing a fixed quantity of liquid from a vented pipette which automatically initializes without accidental dispensing.
More specifically, in accord with one aspect of the invention, there is provided actuating means for dispensing a fixed amount of liquid from a pipette. The pipette for use ~herewith includes means a~ a first end ~3~
for contalning the dispensable liquld, M compression chamber ln fluld communicati.on with the containlng means, compressing means~ including n piston, movably mounted wi~hin the chamber, and means for venting the pipe~te to the atmosphere. The actuatlng means includes mounting means for removably securlng the compression chamber a and moving and se~lling mean6 for sequentlally 1) moving the piston, with the ch~mber ventedp to a predetermined star~ing position relative to the mounting means, and 2) thereafter seallng the venting me~ns.
In accord wi~h a seconcl aspect of the inven-tion, the actuator noted above provides, in combinatlon with a vented pipette, a highly useful dispenser.
Thu6, i~ ~s an advantage of the present inven-tion that an actua~or is provlded for mechanically dis-pensing liquid from a pipette, that avoids both a) acci dental dispensing of ~he liquid during the initiallzing step, and b) undesired altering of the irst dispensed quantity.
It is a related advantage of the lnventlon that pipettes can be used for dispensing without requiring expensive construction~.
Other adv~ntages and eatures will become apparent upon reference ~o the following Description of 25 the Preferred Embodimen~s when read in light of the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. l is a perspective vlew of a dispenser constructed in accordance with the invention, the pipette portion being shown in phantom;
Fig. 2 is a fragmentary vertical seotion view o~ the pipette portion of the invention;
Figs. 3A 3C are fragmentary pl~n views of the actuation arm and of the plston of the pipette as the latter iæ moved into its mounted position in the former;
Fige. 4A-4C are ~ragmentary vertical ~ection vlews ~aken along the lines IVA-IYA, IVB-IVB~ and IVC-IVC, re6pectively of Figs. 3A-3C;
Fi8. 5 is a fragment~ry ver~ical sectlon view taken through member 82 of ~he moving means 80 ~hown in Fig. l; and Fig. 6 is a fragmemtary ~ection view ~aken ~enerally along the line VI-VI of Fig. 5.
DESCRIPTION OF THE :PREFERRED ~MBODIMENTS
The inltializing problems noted above in prior actuators h~ve been solved `by ~hls inventlon, in p~rt by arranglng the actuator so ~ha~ the uppermo~t surf~ce of the piston is ~lw~ys above ~the drivlng 6urface oE the actuator durlng the firEt ~tage of mounting the pipette. Initialiæing occurs using means that auto-matically depress the pi~ton un~il it is lowered to the height o the drlviDg surface. Because th~ actuator i~
constructed ~o that the plston vent is no~ closed un~l after the initializing iB completed, n~ accident~l dis-pensing pressure ~s generated.
Loca~ions such as "above", "below", and the like, and adjectives ~uch as "uppermosti' 9 refer to the noted location6 and ~eatures during the in~ended use of the dispenser of this invent~on.
An actuator 40 a~ shown in Fig. 1 comprises a mounting bracket 42y a pi~ton ac~ua~ion arm 60, and m~ans 80 for moving ~oth ~aid arm ~nd a contacted pip-ette piston. Conveniently, both bracket 42 and means 80 are mounted on a ~upporting surface S, shown in dashed outline. Means 80 are pr fer~bly ixedly mounted on surface 5, whereas bracket 42 is either fixedly moun~ed ~s shown, or pivo~ally mounted for rotation ~bou~ a vertical axi~
Various vented pipet~es are useful w~h th~
actuator. Preferably 3 Fig. 2 3 such a pipe~e 10 com-pr~ses an elongated body 12 having at one e~d 1-4 mean~
20 for corltaining liquid 3 and a~ the end 15 oppo~ite to end 14, a compression chamber 16 in liquid co~munlcation with end ].4 ~la a bore or passageway 18. Containing means 20 preferably is a disposable container as ~hown, that snaps onto end 14. Alterna~ively, a container that is integral with the rest of the pipette is also use-ful. Disposable containers are advantageous in that only this portion of the pipette, rather than the entire pipette, need be thrown away after a given sample is dispensed, to avoid contamination. Such disposable con-tainers have a variety of u~eful shape6, which are not critical to this inventionO
1~ Body end 15 ~erminates in an annular lip 21. A
pis~on 22 is mounted ~or reciprocation within chamber 16, and ls biased upwardly along the axis of bore 18 by means such as a compression spring 24~ End 26 of the piston proximal to bore 18 is prov;ded with an 0-ring seal 28, as is co~ventional. The distal end 30 has an integral sleeve portion 32 that telescopes around end 15 of the pipette. Sleeve portion 32 has an inwardly pro-jecting rib 33 that locks against lip 21 to prevent the piston from ejecting from chsmber 16. A vent aperture 34 extends down the middle of the piston, preferably aligned with bore 18, from piston end 26 to piston end 30. Piston end 30 at the aperture 34 provides the uppermos~ surface of the pipette and the piston, for cooperation with the actuator as hereinafter described.
End 30 has a beveled surface 36 extending from aperture 34 to sleeve portion 32 at an angle adapted to cam the pistonj as is also hereinaf~er described.
Intermediate the ends 14 and 15, body 12 of the pipette is notched at 38 around its circumference, to accurately locate the pipette within the actuator.
Mounting bracket 42, Fig. 1, has a central por-tion 44 ~nd two end flanges 46 and 48, each notched a~
50 and 52, respectively. The notches are sized to receive the pipette. Notch 509 in turn, has a raised lip or ridge 54 adapted to fit within notch 38 of the pipette body 12.
t~
Piston actuation arm 60 comprises pis~on driv-ing ~urface 62, Figs. 1, 4A-4C and 5, provided adjacent the extreme end 64 of the arm. Preferably surface 62 comprises resilient means for sealing vent aperture 34 of the pipette when surface 62 contacts the latter.
Conventional materials such as silicone rubber styrene-butadiene, isoprene, ni~rile rubber and.fluorocarbon rubber are highly useful resilient materials for this purpo~e. Driving sur:Eace 62 is posi~ioned above 1ange 46 by the cantilevered attachment of arm 60 to member 82 of moving means 80, discussed hereinafterO
In accordance ~ith one aspect of the invention, to automatically lower ~he piston to a predetermined starting level, actuation arm 60 furthe~ includes, Figs.
1, 3A-3C, and 4A-4C, a camming surface 66 on the under-side of arm 60~ Camming surface 6$ extends from end 64 to the driving and sealing surface 62 and forms an angle alpha with respect to sealing surface 62, Fig. 4C.
Preferably, angle ~ is at first large, commencing at end 64, and is gradually reduced to provide a convex shape.to camming surface 66. Alternatlvely, a fixed angle adapted to the angle of beveled surface 36 is also useful.
Additionally~ arm 60 includes a groove 68 extending through camming surface 66, from end 64 to a location adjacent to driving and sealing surface 6~, Figs. 4A-4C. Groove 68 is centered within camming ~ur-face 66 so as to be aligned with vent aperture 34 as the pipet~e piston is pushed into place, Figs. 3A-3C.
The cooperation of camming surface 66 and beveled surface 36 of the pipette piston will be readily apparent. As pipette 10 is moved into bracket 42, pis-ton 2~ preferably is arranged to be disposed so that end 30 projects above the plane of driving and sealing sur-face 62, Fig 4A. However, a~ the two portions of the combination converge, camming surface 66 cams against beveled ~ur~ce 36 to lower the pl6ton into its com-pression chamber 16 and to level the pi~on at the height of surace 62, Figs. 3B and 4B. While this occurs, ~hamber 16 and vent aperture 34 are s~lll vented to the ~tmosphere ~hrough groove 68, so tha~ no accidental d~spensing of li~quid occur6. It is not until end 30 of ~he pis~on is allgned and in contac~ with the drivlng ~nd sealing surface 62 th~t vent aperture 34 becomes closed, Flgs. 3C and 4C.
In this fashionj pIs~on 22 is orced ~o start compression within chamber 16 always from ~he same ~tarting level. As a resullt, the firs~ volume diBpensed each time a pipette ls mounlted ~n ac~u~tor 40, i6 pre-dic~ably the same predetermlned fixed volume. There-after, any further lowering of the pi~on ~n response to the lowering of arm 60 cause~ another compresslon build-up withln chamber 16 until another predetermined amount of llquid is accurately dlspen~ed ~rom containing means 20. The stepped sequence repeats wlth ~ddition~l down~
ward movement of ~rm 60: pre~sure builds up, ~nd quantity of liquid is dispensed, relea6ing the pressure. It will be appreciated that CompreQ~iOn chamber 16 ~s vented to the atmosphere only during the initializing that occur6 as depicted in Figs. 3A-3C ~nd 4A-4C. Thereaf~er, it remain~ sealed during the subsequent dispensingO
Arm 60 has a sufficient thickness to accom-modate the expected vari~tions occurring in ~he loca tion of end surface 30 as indlvidual pipettes are mounted in bracket 42. Such variations are generally less than 0.4 cm for the type of pipet~e descrlbed abov~
To accomplish ~he increment~l movement of ~eal-ing surface 62 tha~ lowers pipe~te piston 22 in~o cham-ber 16~ member 82 to which actuation arm 60 is.a~ached is lowered a flxed amoun~ by mo~lng means 80. More specifically, moving means 80 preerably comprise~ a ratchet 84 formed on an lntegral surface oE member 82, Figs. 5 and 6, a box mount 86 for member 82, and n pawl 120 levered within box moun~ 86 to eng~ge r~tchet 84.
Dimensions of these items have been enlarged for clarity. Ratchet 84 comprises a plurality of teeth 85 each of whlch h~s a bottom groove B7 and an ou~er edge 89 proJecting out of ~he groove, Fig. 5. Box mount 86 is provided wi~h a top plate 9~ having a rec~an~ular opening and bushin~s 92 and 93 sized to slidably accom modate member 82. The fit between the bushlng and mem-ber 82 is a friction fit adapted to hold member 82 in place except when it ls lowered by the pawl. A b~ck plate 94 of box moun~ 86 has a shoulder or s~ud 96 ~he Internal end of wh~ch has a bushing 98 against which member 82 slldes. Fron~ plate 100 of box mount 26 18 apertured at 102 to receive a p~wl lever 122. Aper~ure 102 comprlses a top surfa~e 104 that forms a startlng locus for the ~r~vPl of ~he pawl, and therefore the ratchet, and a bo~oming surface 106 for the pawl 2Q lever. Surface 106 is apertured to anchor one end of a biasing compression spring 1~8, the other end of which is secured to a ~tud 112 on the pawl lever.
Pawl 120 is ~ournalled at pin 121 to lever 122 which comprises a bifurcated element h~ving two arms 124 ~nd 126, Fig. 6, ~hat straddle member 82. Arms 124 and 126 are pivotally mounted on back plate 94 at 1~8. A
torsion sprin~ 129 biases pawl 120 agains~ member 82.
By this construction, when lever 122 is lowered against spring 108, Flg. 5, pawl 120 forces member 82 down a fixed distance until lever 122 bottoms against surface 106 of the aperture. For a dispensed qu~ntlty of about 10 ~1, lever 122 rotates abou~ 30~ and pis~on 22 travels about 0.127 cm. As lever 122 is returned to stop agAinst top surface 104, pawl 120 ro~a~es counter clockwise so as to clear the r~tchet tooth ~5 next above it. The distance between bo~tom groove 87 and outer '7~
edge 8~ of each ratchet tooth is designed to be the dls-~ance the pawl travels as lever 122 ls returned to bear a~ainst top surface 104.
Indicia 130 are preferAbly placed on member 82, S Fig. 1, representing cuMulatlve totalg of the volume displaced by the steps or i.ncrements through which mem-ber 82, ~rm 60 and piston 22 are moved. A handle 140 is preferably d~sposed on member 82 to permit manual return of means 80 to ~he initia~ starting position after a pipette has been emptled or is otherwise no longer need-ed. Pawl 120 is rota~d against spring 129, out of the way of teeth ~5, by r~tating a knob, not shown, seeured to the end of pin 1~ he sp~cing o ~he teeth ~5 16 designed so that, when member 82 is pulled up to the starting position shown in Fig. 5, pawl 120 is bottomed in one of the grooves 87.
The materials for the actuator are not crlti-cal 7 and can be selected from conventional ma~erials such as metal or plastic.
The invention h~s been described in detail with particular reference to preferred embodimentg ~hereof, but it will be understood that variations and modlf~ca-tions can be effected within the spirit and scope of the invention.
-
Field oE the Invention This invention relates to apparatus and a pro-cess for dispensing liquids, such as biological liquids, for chemical analysis.
BACKGROUND OF THE INVENTION
Mechanical actuating means, hereinafter "act-uators", have been used prior to this invention to removably mount and to actuate vented pipettes ~o that the contents are dispensed~ By the push of a lever or a button, a ratchet is advanced in steps to cause a piston or plunger of the pipette to repeatedly dispense a pre determined, Eixed ~mount of liquid. The advantage of such a mechanism is that it reduces the opportunity for the errors that oten occur when pipettes are operated manually. When a new pipette is filled for dispensing, the previously emptied pipette is removed and the new one mounted in the ac~uator. Examples of such devices are described in U.S. Paten~ No. 3,161,323.
One difficulty with such mechanical actuators is that, unless prohibi~ively expensive pipette designs are used, the piston of the pipette is not reliably at a predetermined height as to accurately line up with the driving surface of the actuator. Because of this, either the actuator or the pipette must be adju~ted by less than a whole s~ep to bring the actuator's driving surface into contact with the pis~on of the pipet~e, a process hereinafter referred to as "initializing.~' How-ever, initializing by altering the location of the driv-ing surface is generally not desirable. It is particu-larly unsatisfactory when the actuator is programmed to operate in fixed steps only, as noted. If the pipette piston's initial location should be between one of the fixed levels defining the steps, the driving surface wo~ld have to be moved downward or upward during ini-tializing by less than a whole step. Such movement would alter the volume of the first quantity to be dis~
pensed.
On the other hand, initializing by adjustirg the pipette and particularly ~he piston of the pipette has not been desirable prior to this invention. At best, manually readjusting the pipette to ob~ain contact with ~he driving surface i~ time consuming. At worst, such adjustment might requlre that the pis~on be lowered to the level of the driving surface. If the vent of the pipette accidentally becomes closed while the piston is being so lowered, undesired liquid dispensing occurs.
Since the pipette vent is conveniently an aperture through the top o the piston at the very place force is normally applied to depress ~he piston, it has been dif ficult to downwardly adjus~ the pis~on without closing the vent.
Because of the above problems, use of mechani-cal actuators of pipettes has been less than ~atisfac-tory. Particularly the initializing problem has been acute when many individual pipettes are to be sequen-tially inserted into the actuator, each with a poten-tially different ini~ial piston location.
Therefore, what has been needed is a mechanical actuator for a pipet~e and par~icularly a vented pipette~ which automatically orients the piston and actuator driving surface wi~hout any loss of the liquid contained in the pipette.
SUMMARY OF THE INYENTION
The invention is directed to appara~us and a process for dispensing a fixed quantity of liquid from a vented pipette which automatically initializes without accidental dispensing.
More specifically, in accord with one aspect of the invention, there is provided actuating means for dispensing a fixed amount of liquid from a pipette. The pipette for use ~herewith includes means a~ a first end ~3~
for contalning the dispensable liquld, M compression chamber ln fluld communicati.on with the containlng means, compressing means~ including n piston, movably mounted wi~hin the chamber, and means for venting the pipe~te to the atmosphere. The actuatlng means includes mounting means for removably securlng the compression chamber a and moving and se~lling mean6 for sequentlally 1) moving the piston, with the ch~mber ventedp to a predetermined star~ing position relative to the mounting means, and 2) thereafter seallng the venting me~ns.
In accord wi~h a seconcl aspect of the inven-tion, the actuator noted above provides, in combinatlon with a vented pipette, a highly useful dispenser.
Thu6, i~ ~s an advantage of the present inven-tion that an actua~or is provlded for mechanically dis-pensing liquid from a pipette, that avoids both a) acci dental dispensing of ~he liquid during the initiallzing step, and b) undesired altering of the irst dispensed quantity.
It is a related advantage of the lnventlon that pipettes can be used for dispensing without requiring expensive construction~.
Other adv~ntages and eatures will become apparent upon reference ~o the following Description of 25 the Preferred Embodimen~s when read in light of the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. l is a perspective vlew of a dispenser constructed in accordance with the invention, the pipette portion being shown in phantom;
Fig. 2 is a fragmentary vertical seotion view o~ the pipette portion of the invention;
Figs. 3A 3C are fragmentary pl~n views of the actuation arm and of the plston of the pipette as the latter iæ moved into its mounted position in the former;
Fige. 4A-4C are ~ragmentary vertical ~ection vlews ~aken along the lines IVA-IYA, IVB-IVB~ and IVC-IVC, re6pectively of Figs. 3A-3C;
Fi8. 5 is a fragment~ry ver~ical sectlon view taken through member 82 of ~he moving means 80 ~hown in Fig. l; and Fig. 6 is a fragmemtary ~ection view ~aken ~enerally along the line VI-VI of Fig. 5.
DESCRIPTION OF THE :PREFERRED ~MBODIMENTS
The inltializing problems noted above in prior actuators h~ve been solved `by ~hls inventlon, in p~rt by arranglng the actuator so ~ha~ the uppermo~t surf~ce of the piston is ~lw~ys above ~the drivlng 6urface oE the actuator durlng the firEt ~tage of mounting the pipette. Initialiæing occurs using means that auto-matically depress the pi~ton un~il it is lowered to the height o the drlviDg surface. Because th~ actuator i~
constructed ~o that the plston vent is no~ closed un~l after the initializing iB completed, n~ accident~l dis-pensing pressure ~s generated.
Loca~ions such as "above", "below", and the like, and adjectives ~uch as "uppermosti' 9 refer to the noted location6 and ~eatures during the in~ended use of the dispenser of this invent~on.
An actuator 40 a~ shown in Fig. 1 comprises a mounting bracket 42y a pi~ton ac~ua~ion arm 60, and m~ans 80 for moving ~oth ~aid arm ~nd a contacted pip-ette piston. Conveniently, both bracket 42 and means 80 are mounted on a ~upporting surface S, shown in dashed outline. Means 80 are pr fer~bly ixedly mounted on surface 5, whereas bracket 42 is either fixedly moun~ed ~s shown, or pivo~ally mounted for rotation ~bou~ a vertical axi~
Various vented pipet~es are useful w~h th~
actuator. Preferably 3 Fig. 2 3 such a pipe~e 10 com-pr~ses an elongated body 12 having at one e~d 1-4 mean~
20 for corltaining liquid 3 and a~ the end 15 oppo~ite to end 14, a compression chamber 16 in liquid co~munlcation with end ].4 ~la a bore or passageway 18. Containing means 20 preferably is a disposable container as ~hown, that snaps onto end 14. Alterna~ively, a container that is integral with the rest of the pipette is also use-ful. Disposable containers are advantageous in that only this portion of the pipette, rather than the entire pipette, need be thrown away after a given sample is dispensed, to avoid contamination. Such disposable con-tainers have a variety of u~eful shape6, which are not critical to this inventionO
1~ Body end 15 ~erminates in an annular lip 21. A
pis~on 22 is mounted ~or reciprocation within chamber 16, and ls biased upwardly along the axis of bore 18 by means such as a compression spring 24~ End 26 of the piston proximal to bore 18 is prov;ded with an 0-ring seal 28, as is co~ventional. The distal end 30 has an integral sleeve portion 32 that telescopes around end 15 of the pipette. Sleeve portion 32 has an inwardly pro-jecting rib 33 that locks against lip 21 to prevent the piston from ejecting from chsmber 16. A vent aperture 34 extends down the middle of the piston, preferably aligned with bore 18, from piston end 26 to piston end 30. Piston end 30 at the aperture 34 provides the uppermos~ surface of the pipette and the piston, for cooperation with the actuator as hereinafter described.
End 30 has a beveled surface 36 extending from aperture 34 to sleeve portion 32 at an angle adapted to cam the pistonj as is also hereinaf~er described.
Intermediate the ends 14 and 15, body 12 of the pipette is notched at 38 around its circumference, to accurately locate the pipette within the actuator.
Mounting bracket 42, Fig. 1, has a central por-tion 44 ~nd two end flanges 46 and 48, each notched a~
50 and 52, respectively. The notches are sized to receive the pipette. Notch 509 in turn, has a raised lip or ridge 54 adapted to fit within notch 38 of the pipette body 12.
t~
Piston actuation arm 60 comprises pis~on driv-ing ~urface 62, Figs. 1, 4A-4C and 5, provided adjacent the extreme end 64 of the arm. Preferably surface 62 comprises resilient means for sealing vent aperture 34 of the pipette when surface 62 contacts the latter.
Conventional materials such as silicone rubber styrene-butadiene, isoprene, ni~rile rubber and.fluorocarbon rubber are highly useful resilient materials for this purpo~e. Driving sur:Eace 62 is posi~ioned above 1ange 46 by the cantilevered attachment of arm 60 to member 82 of moving means 80, discussed hereinafterO
In accordance ~ith one aspect of the invention, to automatically lower ~he piston to a predetermined starting level, actuation arm 60 furthe~ includes, Figs.
1, 3A-3C, and 4A-4C, a camming surface 66 on the under-side of arm 60~ Camming surface 6$ extends from end 64 to the driving and sealing surface 62 and forms an angle alpha with respect to sealing surface 62, Fig. 4C.
Preferably, angle ~ is at first large, commencing at end 64, and is gradually reduced to provide a convex shape.to camming surface 66. Alternatlvely, a fixed angle adapted to the angle of beveled surface 36 is also useful.
Additionally~ arm 60 includes a groove 68 extending through camming surface 66, from end 64 to a location adjacent to driving and sealing surface 6~, Figs. 4A-4C. Groove 68 is centered within camming ~ur-face 66 so as to be aligned with vent aperture 34 as the pipet~e piston is pushed into place, Figs. 3A-3C.
The cooperation of camming surface 66 and beveled surface 36 of the pipette piston will be readily apparent. As pipette 10 is moved into bracket 42, pis-ton 2~ preferably is arranged to be disposed so that end 30 projects above the plane of driving and sealing sur-face 62, Fig 4A. However, a~ the two portions of the combination converge, camming surface 66 cams against beveled ~ur~ce 36 to lower the pl6ton into its com-pression chamber 16 and to level the pi~on at the height of surace 62, Figs. 3B and 4B. While this occurs, ~hamber 16 and vent aperture 34 are s~lll vented to the ~tmosphere ~hrough groove 68, so tha~ no accidental d~spensing of li~quid occur6. It is not until end 30 of ~he pis~on is allgned and in contac~ with the drivlng ~nd sealing surface 62 th~t vent aperture 34 becomes closed, Flgs. 3C and 4C.
In this fashionj pIs~on 22 is orced ~o start compression within chamber 16 always from ~he same ~tarting level. As a resullt, the firs~ volume diBpensed each time a pipette ls mounlted ~n ac~u~tor 40, i6 pre-dic~ably the same predetermlned fixed volume. There-after, any further lowering of the pi~on ~n response to the lowering of arm 60 cause~ another compresslon build-up withln chamber 16 until another predetermined amount of llquid is accurately dlspen~ed ~rom containing means 20. The stepped sequence repeats wlth ~ddition~l down~
ward movement of ~rm 60: pre~sure builds up, ~nd quantity of liquid is dispensed, relea6ing the pressure. It will be appreciated that CompreQ~iOn chamber 16 ~s vented to the atmosphere only during the initializing that occur6 as depicted in Figs. 3A-3C ~nd 4A-4C. Thereaf~er, it remain~ sealed during the subsequent dispensingO
Arm 60 has a sufficient thickness to accom-modate the expected vari~tions occurring in ~he loca tion of end surface 30 as indlvidual pipettes are mounted in bracket 42. Such variations are generally less than 0.4 cm for the type of pipet~e descrlbed abov~
To accomplish ~he increment~l movement of ~eal-ing surface 62 tha~ lowers pipe~te piston 22 in~o cham-ber 16~ member 82 to which actuation arm 60 is.a~ached is lowered a flxed amoun~ by mo~lng means 80. More specifically, moving means 80 preerably comprise~ a ratchet 84 formed on an lntegral surface oE member 82, Figs. 5 and 6, a box mount 86 for member 82, and n pawl 120 levered within box moun~ 86 to eng~ge r~tchet 84.
Dimensions of these items have been enlarged for clarity. Ratchet 84 comprises a plurality of teeth 85 each of whlch h~s a bottom groove B7 and an ou~er edge 89 proJecting out of ~he groove, Fig. 5. Box mount 86 is provided wi~h a top plate 9~ having a rec~an~ular opening and bushin~s 92 and 93 sized to slidably accom modate member 82. The fit between the bushlng and mem-ber 82 is a friction fit adapted to hold member 82 in place except when it ls lowered by the pawl. A b~ck plate 94 of box moun~ 86 has a shoulder or s~ud 96 ~he Internal end of wh~ch has a bushing 98 against which member 82 slldes. Fron~ plate 100 of box mount 26 18 apertured at 102 to receive a p~wl lever 122. Aper~ure 102 comprlses a top surfa~e 104 that forms a startlng locus for the ~r~vPl of ~he pawl, and therefore the ratchet, and a bo~oming surface 106 for the pawl 2Q lever. Surface 106 is apertured to anchor one end of a biasing compression spring 1~8, the other end of which is secured to a ~tud 112 on the pawl lever.
Pawl 120 is ~ournalled at pin 121 to lever 122 which comprises a bifurcated element h~ving two arms 124 ~nd 126, Fig. 6, ~hat straddle member 82. Arms 124 and 126 are pivotally mounted on back plate 94 at 1~8. A
torsion sprin~ 129 biases pawl 120 agains~ member 82.
By this construction, when lever 122 is lowered against spring 108, Flg. 5, pawl 120 forces member 82 down a fixed distance until lever 122 bottoms against surface 106 of the aperture. For a dispensed qu~ntlty of about 10 ~1, lever 122 rotates abou~ 30~ and pis~on 22 travels about 0.127 cm. As lever 122 is returned to stop agAinst top surface 104, pawl 120 ro~a~es counter clockwise so as to clear the r~tchet tooth ~5 next above it. The distance between bo~tom groove 87 and outer '7~
edge 8~ of each ratchet tooth is designed to be the dls-~ance the pawl travels as lever 122 ls returned to bear a~ainst top surface 104.
Indicia 130 are preferAbly placed on member 82, S Fig. 1, representing cuMulatlve totalg of the volume displaced by the steps or i.ncrements through which mem-ber 82, ~rm 60 and piston 22 are moved. A handle 140 is preferably d~sposed on member 82 to permit manual return of means 80 to ~he initia~ starting position after a pipette has been emptled or is otherwise no longer need-ed. Pawl 120 is rota~d against spring 129, out of the way of teeth ~5, by r~tating a knob, not shown, seeured to the end of pin 1~ he sp~cing o ~he teeth ~5 16 designed so that, when member 82 is pulled up to the starting position shown in Fig. 5, pawl 120 is bottomed in one of the grooves 87.
The materials for the actuator are not crlti-cal 7 and can be selected from conventional ma~erials such as metal or plastic.
The invention h~s been described in detail with particular reference to preferred embodimentg ~hereof, but it will be understood that variations and modlf~ca-tions can be effected within the spirit and scope of the invention.
-
Claims (8)
1. In a dispenser including a pipette comprising means at a first end for containing liquid for dispensing, a compression chamber in fluid communication with said first end, compressing means, including a piston, for providing fluid com-pression within said chamber, and means for venting said chamber to the atmosphere, and actuating means including mounting means for receiving said pipette and for removably securing the compression chamber of said pipette in a fixed position and means for engaging and moving said compressing means by a predetermined distance to dispense a fixed amount of liquid;
the improvement wherein said actuating means includes moving and sealing means, operable during receipt of said pipette, for sequentially: (1) moving said piston with said chamber in a vented condition, to a predetermined starting position relative to said mounting means, and (2) thereafter sealing said venting means.
the improvement wherein said actuating means includes moving and sealing means, operable during receipt of said pipette, for sequentially: (1) moving said piston with said chamber in a vented condition, to a predetermined starting position relative to said mounting means, and (2) thereafter sealing said venting means.
2. A dispenser as defined in claim 1, wherein said venting means comprises a vent aperture extending through said piston to an end of said pipette that is opposite said first end, and wherein said actuating means comprises a cantilevered piston-actuation arm having a camming sur-face and a sealing surface adapted to seal against said vent aperture when said pipette is fully mounted in said actuating means, said camming surface extending from the cantilevered end of said actuation arm to said sealing surface, said camming surface having a groove extending from said cantilevered end to a location adjacent said sealing surface, said groove being positioned to expose to the atmosphere said vent aperture as said pipette is being mounted in said actuating means and lowered to said starting position by said camming surface.
3. A dispenser as defined in claim 2, and fur-ther including incrementing means for moving in incre-ments said actuation arm and said piston to provide compression within said chamber, each increment corresponding to a desired volume of dispensed liquid.
4. A dispenser as defined in claim 3, wherein said incrementing means comprises a pawl and ratchet, said actuation arm being operatively connected to a mem-ber having said ratchet as a portion thereof.
5. Actuating means for dispensing a fixed amount of liquid from a pipette having means at one end for containing the dispensable liquid, a compression chamber in fluid communication with said containing means, compressing means, including a piston movably mounted within said chamber, for providing compression within said chamber, and means for venting the pipette to the atmosphere;
the actuating means comprising means for receiving said pipette and for remov-ably mounting said compression chamber in a fixed position, means for engaging and moving said piston a predetermined distance to dispense a fixed amount of liquid, and means, operable during receipt of said pipette, for sequentially: (1) moving said piston with said chamber in a vented condition, to a predetermined starting position relative to said mounting means, and (2) thereafter sealing said venting means.
the actuating means comprising means for receiving said pipette and for remov-ably mounting said compression chamber in a fixed position, means for engaging and moving said piston a predetermined distance to dispense a fixed amount of liquid, and means, operable during receipt of said pipette, for sequentially: (1) moving said piston with said chamber in a vented condition, to a predetermined starting position relative to said mounting means, and (2) thereafter sealing said venting means.
6. Actuating means as defined in claim 5, wherein the pipette venting means comprises a vent aper-ture extending through said piston to an end of said pipette opposite to said one end, and wherein said actuating means comprises a cantilevered piston-actuation arm having a camming sur-face and a sealing surface adapted to seal against said vent aperture when said pipette is fully mounted in said actuating means, said camming surface extending from the cantilevered end of said actuation arm to said sealing surface, said camming surface having a groove extending from said cantilevered end to a location adjacent said sealing surface, said groove being positioned to expose to the atmosphere said vent aperture as said pipette is being mounted in said actuating means and lowered to said starting position by said camming surface.
7. Actuating means as defined in claim 6, and further including incrementing means for moving in increments said actuation arm and said piston sealed against said sealing surface to compress air within said chamber, each increment corresponding to a desired volume of dispensed liquid.
8. Actuating means as defined in claim 7, wherein said incrementing means comprises a pawl and ratchet, said actuation arm being operatively connected to a member having said ratchet as a portion thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US362,931 | 1982-03-29 | ||
| US06/362,931 US4437586A (en) | 1982-03-29 | 1982-03-29 | Mechanically actuated pipette dispenser |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1192876A true CA1192876A (en) | 1985-09-03 |
Family
ID=23428106
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000409399A Expired CA1192876A (en) | 1982-03-29 | 1982-08-13 | Mechanically actuated pipette dispenser |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4437586A (en) |
| CA (1) | CA1192876A (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5074443A (en) * | 1989-12-20 | 1991-12-24 | Nordson Corporation | Adaptor for liquid dispensing syringe |
| US5568881A (en) * | 1995-07-31 | 1996-10-29 | Chi; Wen Y. | Pipette tip dispenser |
| US6734026B1 (en) * | 1999-05-28 | 2004-05-11 | Drummond Scientific Company | Pipette gun and holster assembly |
| JP4399072B2 (en) * | 1999-12-03 | 2010-01-13 | ノードソン株式会社 | Liquid material discharge device |
| US6652015B1 (en) * | 2001-01-26 | 2003-11-25 | Ta Instruments-Waters Llc | Gripper device |
| WO2009046227A1 (en) | 2007-10-02 | 2009-04-09 | Theranos, Inc. | Modular point-of-care devices and uses thereof |
| JP4927920B2 (en) * | 2009-09-25 | 2012-05-09 | ノードソン株式会社 | Liquid material discharge device |
| USD667961S1 (en) * | 2009-12-02 | 2012-09-25 | Mettler-Toledo Ag | Laboratory instrument |
| EP3660517B1 (en) * | 2010-11-23 | 2024-04-03 | Andrew Alliance S.A | Apparatus for programmable manipulation of pipettes |
| CA3097861A1 (en) | 2011-01-21 | 2012-07-26 | Labrador Diagnostics Llc | Systems and methods for sample use maximization |
| US9168030B2 (en) * | 2011-08-11 | 2015-10-27 | Robert A. Dracker | Envelope and procurement stand for placental transport and stem cell collection |
| US8435738B2 (en) | 2011-09-25 | 2013-05-07 | Theranos, Inc. | Systems and methods for multi-analysis |
| US9664702B2 (en) | 2011-09-25 | 2017-05-30 | Theranos, Inc. | Fluid handling apparatus and configurations |
| US9619627B2 (en) | 2011-09-25 | 2017-04-11 | Theranos, Inc. | Systems and methods for collecting and transmitting assay results |
| US8840838B2 (en) | 2011-09-25 | 2014-09-23 | Theranos, Inc. | Centrifuge configurations |
| US8475739B2 (en) | 2011-09-25 | 2013-07-02 | Theranos, Inc. | Systems and methods for fluid handling |
| US20140170735A1 (en) | 2011-09-25 | 2014-06-19 | Elizabeth A. Holmes | Systems and methods for multi-analysis |
| US9632102B2 (en) | 2011-09-25 | 2017-04-25 | Theranos, Inc. | Systems and methods for multi-purpose analysis |
| US9268915B2 (en) | 2011-09-25 | 2016-02-23 | Theranos, Inc. | Systems and methods for diagnosis or treatment |
| US10012664B2 (en) | 2011-09-25 | 2018-07-03 | Theranos Ip Company, Llc | Systems and methods for fluid and component handling |
| US9250229B2 (en) | 2011-09-25 | 2016-02-02 | Theranos, Inc. | Systems and methods for multi-analysis |
| US9810704B2 (en) | 2013-02-18 | 2017-11-07 | Theranos, Inc. | Systems and methods for multi-analysis |
| US10525460B2 (en) * | 2016-06-15 | 2020-01-07 | Hamilton Company | Pipetting device, pipette tip coupler, and pipette tip: devices and methods |
-
1982
- 1982-03-29 US US06/362,931 patent/US4437586A/en not_active Expired - Fee Related
- 1982-08-13 CA CA000409399A patent/CA1192876A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4437586A (en) | 1984-03-20 |
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