Pipetting apparatus and method

Claim 2

Pipetting apparatus adapted for use with a plurality of interchangeable pipets, the apparatus com-prising a pipettor; means on the pipettor for selectively operatively engaging a pipet, said means including a micropipet in the pipettor adapted to communicate with a pipet operatively engaged therewith and gasket means for releaseably engaging an end portion of a pipet to provide sealingly communicative engagement of the pipet and micropipet; a hollow suction line in the pipettor; a hollow pressure line in the pipettor; valve means in the pipettor for providing selective communication and sealing between the suction and pressure lines and the micropipet, the valve means being operable between a charging mode in which the micropipet communicates with the suction line and is sealed from the pressure line, a sealing mode in which the micropipet is sealed from communication with both lines whereby a predetermined volume of fluid in the micropipet and a pipet engaged therewith is separated from communication with the suction line, and a discharging mode wherein the micropipet is sealed from the suction line and communicates with the pressure line; means for coupling the suction line to a source of suction adapted to draw a column of fluid through the micropipet and a pipet engaged therewith and into the suction line when the valve means is in the charging mode; means for coupling the pressure line to a source of fluid pressure adapted to provide pressure in the pressure line for discharging the micropipet when the valve is in the discharging mode.

Claim 3

Pipetting apparatus adapted for use with a plurality of interchangeable pipets, the apparatus com-prising a pipettor; means on the pipettor for selectively operatively engaging a pipet, said means including a micropipet in the pipettor adapted to communicate with a pipet operatively engaged therewith and gasket means for releaseably engaging an end portion of a pipet to provide sealingly communicative engagement of the pipet and micropipet; a hollow suction line in the pipettor; a hollow pressure line in the pipettor; valve means in the pipettor for providing selective communication and sealing between the suction and pressure lines and the micropipet, the valve means being operable between a charging mode in which the micropipet communicates with the suction line and is sealed from the pressure line, a sealing mode in which the micropipet is sealed from communication with both lines whereby a predetermined volume of fluid in the micropipet and a pipet engaged therewith is separated from communication with the suction line, and a discharging mode wherein the micropipet is sealed from the suction line and communicates with the pressure line; means for coupling the suction line to a source of suction adapted to draw a column of fluid through the micropipet and a pipet engaged therewith and into the suction line when the valve means is in the charging mode; means for coupling the pressure line to a source of fluid pressure adapted to provide pressure in the pressure line for discharging the micropipet when the valve is in the discharging mode.

Claim 4

Pipetting apparatus adapted for use with a plurality of interchangeable pipets, the apparatus com-prising a pipettor; means on the pipettor for selectively operatively engaging a pipet, said means including a micropipet in the pipettor adapted to communicate with a pipet operatively engaged therewith and gasket means for releaseably engaging an end portion of a pipet to provide sealingly communicative engagement of the pipet and micropipet; a hollow suction line in the pipettor; a hollow pressure line in the pipettor; valve means in the pipettor for providing selective communication and sealing between the suction and pressure lines and the micropipet, the valve means being operable between a charging mode in which the micropipet communicates with the suction line and is sealed from the pressure line, a sealing mode in which the micropipet is sealed from communication with both lines whereby a predetermined volume of fluid in the micropipet and a pipet engaged therewith is separated from communication with the suction line, and a discharging mode wherein the micropipet is sealed from the suction line and communicates with the pressure line; means for coupling the suction line to a source of suction adapted to draw a column of fluid through the micropipet and a pipet engaged therewith and into the suction line when the valve means is in the charging mode; means for coupling the pressure line to a source of fluid pressure adapted to provide pressure in the pressure line for discharging the micropipet when the valve is in the discharging mode.

Claim 5

Apparatus of claim 1 wherein the valve means is adapted to mechanically divide a fluid column which has been drawn into the micropipet and suction line during the charging mode into an integral fluid portion of predetermined volume enclosed by the micropipet and a pipet engaged therewith and a second integral fluid portion within the suction line, the valve means being adapted to divide the fluid column at a single location within the valve.

Claim 6

Apparatus of claim 1 further comprising manually operable means on the pipettor for disposing the valve means in a selected mode, and means for indicating the movement of a liquid column beyond the micropipet.

Claim 7

Apparatus of claim 3 wherein the indicating means comprise a transparent wall portion of the suction line to permit visual observation of a liquid column moving therethrough and a fluid resistance in the suction line adapted to impede the flow rate of such liquid column a predetermined distance along the suction line downstream of the valve.

Claim 8

Apparatus of claim 3 wherein the indicating means includes an electrical contact in the suction line and electrically conductive leads on the pipettor and on a pipet engaged therewith adapted to contact a liquid electrolyte to be pipetted, the indicator means being responsive to an electrical circuit through a column of the liquid electRolyte drawn into the suction line to the contact for sensing the completion of charging.

Claim 9

Apparatus of claim 5 further comprising biasing means in the pipettor for normally biasing the valve means toward the sealing mode, locking means for releaseably maintaining the valve means in the charging mode, and means responsive to an electric current conducted by a liquid electrolyte column through the valve means, micropipet and a pipet engaged therewith for releasing the locking means.

Claim 10

Apparatus of claim 1 wherein the valve means comprises a valve base mounted in the pipettor and having a bore therethrough, portions of the base surrounding the bore defining wall portions of the micropipet; and a valve block having separate bores therethrough, portions of the block surrounding the bores defining wall portions of the suction line and pressure line, said wall portions being selectively sealably engageable with the wall portions of the micropipet, means for mounting the valve block for movement relative to the valve base, and means for moving the valve block relative to the valve base between relative positions in which the micropipet communicates with one of said lines and is sealed from communication with the other of said lines, and a position in which the micropipet is sealed from communication with both lines by sealing engagement of wall portions of the micropipet with the valve block.

Claim 11

Apparatus of claim 7 wherein the valve base includes a hollow stud surrounding the micropipet and defining a wall portion thereof, the stud extending beyond a face of the valve base toward the valve block, the stud terminating in a sealing face adapted to sealingly engage a portion of a face of the valve block to provide sealing communication between the micropipet and a single one of said lines, and means including said stud for maintaining a major proportion of the opposed faces of the base and block spaced from each other to permit one of said lines to communicate with atmosphere between the opposed spaced faces when said line is sealed from communication with the micropipet.

Claim 12

Apparatus of claim 8 wherein the portions of the micropipet, suction line and pressure line at the opposed faces of the block and base are substantially cylindrical and having substantially similar diameters and substantially parallel axes; and wherein the valve block is mounted for relative movement in a plane substantially normal to the axes of the micropipet and lines.

Claim 13

Apparatus of claim 8 wherein the portions of the micropipet, suction line and pressure line at the opposed faces of the block and base are substantially cylindrical and having substantially similar diameters, wherein the sealing face of the stud extends radially outwardly from the micropipet a distance of between one and two times the diameter of the micropipet, and wherein the suction and pressure lines are spaced sufficiently from each other to prevent simultaneous sealing of both lines when the sealing face of the stud is sealingly engaged with a portion of the block face intermediate the suction and pressure lines.

Claim 14

Pipetting apparatus comprising: pipet operating means including a pipettor; suction means for providing pipet-charging suction to the pipettor; pressure means for providing pipet-discharging pressure to the pipettor; hollow suction and pressure lines in the pipettor adapted to apply suction and pressure to a pipet; means including suction and pressure connecting tubes for providing communication between the suction and pressure lines and the corresponding suction and pressure means while permitting movement of the pipettor relative to the suction and pressure means; sealing means on the pipettor for operatively engaging an end of a pipet; and valving means on the pipettor for selectively charging a fluid into a pipet engaged by the sealing means and partially through such pipet into the suction line, selectively dividing fluid so charged into a continuous pipetted portion in the pipet and a single continuous fluid portion in the suction line, and selectively discharging the pipetted fluid portion under pressure from the pressure line, said valving means including a valve base having a cylindrical micropipet bore therein adapted to communicate with a pipet engaged by the sealing means; a valve block having cyclindrical suction and pressure line bores therein, the axes of said bores being parallel to the axis of the micropipet bore, means including wall portions of said parallel bores at a planar interface of the valve base and valve block for sealing a selected line bore in communication with said micropipet bore; means for movably mounting the valve block for limited motion relative to the base in a plane transverse to the parallel axes of the bores between a position in which a selected one of said line bores sealingly communicates with the micropipet bore and a position in which the micropipet bore is sealed; and means on the pipettor operably engaged with the valve means for selectively moving the block relative to the base.

Claim 15

Pipetting apparatus comprising: pipet operating means including a pipettor; suction means for providing pipet-charging suction to the pipettor; pressure means for providing pipet-discharging pressure to the pipettor; hollow suction and pressure lines in the pipettor adapted to apply suction and pressure to a pipet; means including suction and pressure connecting tubes for providing communication between the suction and pressure lines and the corresponding suction and pressure means while permitting movement of the pipettor relative to the suction and pressure means; sealing means on the pipettor for operatively engaging an end of a pipet; and valving means on the pipettor for selectively charging a fluid into a pipet engaged by the sealing means and partially through such pipet into the suction line, selectively dividing fluid so charged into a continuous pipetted portion in the pipet and a single continuous fluid portion in the suction line, and selectively discharging the pipetted fluid portion under pressure from the pressure line, said valving means including a valve base having a cylindrical micropipet bore therein adapted to communicate with a pipet engaged by the sealing means; a valve block having cyclindrical suction and pressure line bores therein, the axes of said bores being parallel to the axis of the micropipet bore, means including wall portions of said parallel bores at a planar interface of the valve base and valve block for sealing a selected line bore in communication with said micropipet bore; means for movably mounting the valve block for limited motion relative to the base in a plane transverse to the parallel axes of the bores between a position in which a selected one of said line bores sealingly communicates with the micropipet bore and a position in which the micropipet bore is sealed; and means on the pipettor operably engaged with the valve means for selectively moving the block relative to the base.

Claim 16

Apparatus of claim 11 wherein the suction connecting tube includes a portion which is wettable by the fluid.

Claim 17

Apparatus of claim 11 further comprising a fluid resistance in the suction line upstream of the valving means, said fluid resistance being adapted to impede the flow of liquid along the suction line.

Claim 18

Apparatus of claim 11 wherein the suction means and pressure means include the intake and exhaust of a single pump, said pump being adapted to operate independently of the operation of the valving means, and wherein the valving means includes means for selectively venting the suction line and pressure line when said lines are sealed from communication with a pipet.

Claim 19

Apparatus of claim 11 further comprising means operable independently of the suction means, pressure means and valve means for selectively regulating the pressure in the pressure line and means for independently regulating the suction in the suction line.

Claim 20

The apparatus of claim 11 wherein the valving means includes wall portions of the micropipet bore extending beyond the base toward the block and terminating in a planar face slidably sealingly engaged against a planar face of the block which includes wall portions of the parallel suction and pressure lines.

Claim 21

The apparatus of claim 16 wherein the valving means further includes means for limiting the relative planar motion of the base and block to a distance between about one and about six times the diameter of the micropipet bore.

Claim 22

In a pipetting apparatus comprising means for engaging a pipet to be employed in pipetting a liquid, means including a valve for selectively charging liquid into a pipet by suction, sealing liquid so charged in the pipet and discharging liquid from the pipet under pressure, the pipet having a sealing and face adapted to releaseably sealingly engage the pipettor and an opposed pipet tip through which pipetted liquid is to be charged and discharged, the improvement wherein the pipet includes an outwardly-extending collar a predetermined distance from the sealing end face thereof, wherein the apparatus further comprises a pipet-retaining member including a pair of fork arms adapted to receive a portion of the pipet intermediate the collar and tip between the fork arms, the fork arms being adapted to engage the pipet collar, the fork arms being mounted on the apparatus for movement of the fork arms relative to the pipet engaging means between a first position in which the fork arms and pipet-engaging means are in pipet-retaining relation to each other and a second pipet-releasing position in which the fork arms are displaced from the pipet-engaging means.

Claim 23

In a pipetting apparatus comprising means for engaging a pipet to be employed in pipetting a liquid, means including a valve for selectively charging liquid into a pipet by suction, sealing liquid so charged in the pipet and discharging liquid from the pipet under pressure, the pipet having a sealing and face adapted to releaseably sealingly engage the pipettor and an opposed pipet tip through which pipetted liquid is to be charged and discharged, the improvement wherein the pipet includes an outwardly-extending collar a predetermined distance from the sealing end face thereof, wherein the apparatus further comprises a pipet-retaining member including a pair of fork arms adapted to receive a portion of the pipet intermediate the collar and tip between the fork arms, the fork arms being adapted to engage the pipet collar, the fork arms being mounted on the apparatus for movement of the fork arms relative to the pipet engaging means between a first position in which the fork arms and pipet-engaging means are in pipet-retaining relation to each other and a second pipet-releasing position in which the fork arms are displaced from the pipet-engaging means.

Claim 24

Apparatus of claim 18 wherein the apparatus includes a pipet-receiving socket adapted to slidably engage a portion of a pipet and guide the sealing face of the pipet toward engagement with the pipet-engaging means during motion of the fork arms toward the first position thereof.

Claim 25

Apparatus of claim 18 wherein the apparatus includes a pipet-receiving socket adapted to slidably engage a pipet and guide the sealing face thereof toward engagement with the pipet-engaging means, the socket having a peripheral lip adapted to slidably engage a corresponding end portion of a pipet to guide the sealing face into the socket.

Claim 26

Apparatus of claim 20 wherein the pipet engaging means includes a micropipet adapted to communicate with the interior of the pipet and a gasket surrounding the micropipet adapted to engage the sealing face of the pipet, and wherein the socket includes an inner portion adapted to guide the sealing face into sealing engagement with the gasket so that the micropipet communicates with the interior of the pipet, and an outer flared socket portion adapted to slidably engage an end portion of the pipet and guide the sealing face thereof into guiding engagement with the inner socket portion.

Claim 27

A pipet comprising a tubular body having, at opposed ends of the body, a pipet tip and a sealing face adapted to be releaseably sealingly engaged with a pipettor; the pipet being adapted to contain a predetermined volume of fluid between the tip and sealing face; and a collar extending outwardly from the pipet body, the collar being disposed on the pipet body intermediate the ends thereof and a predetermined distance from the sealing face thereof, the collar being adapted to be nestingly engaged by a corresponding portion of a pipet-retaining member on a pipettor.

Claim 28

A pipet comprising a tubular body having, at opposed ends of the body, a pipet tip and a sealing face adapted to be releaseably sealingly engaged with a pipettor; the pipet being adapted to contain a predetermined volume of fluid between the tip and sealing face; and a collar extending outwardly from the pipet body, the collar being disposed on the pipet body intermediate the ends thereof and a predetermined distance from the sealing face thereof, the collar being adapted to be nestingly engaged by a corresponding portion of a pipet-retaining member on a pipettor.

Claim 29

A pipet of claim 22 further comprising electrically conductive means on the exterior of the pipet for conducting an electric current between the pipet tip and an electrical contact on a pipettor.

Claim 30

A pipet of claim 22 wherein the pipet body includes a beveled end portion at the sealing face, the beveled end portion extending about the sealing face and being adapted to slidably engage a wall of a pipet-receiving socket in a pipettor.

Claim 31

A pipet of claim 24 further comprising indicia disposed on the pipet body, said indicia being in standard volumetric units and indicating a volume corresponding to the predetermined internal volume of the pipet between the tip and sealing face thereof.

Claim 32

A pipet of claim 25 wherein the indicia on the pipet indicate a volume greater than the total internal volume of the pipet by a predetermined volumetric increment corresponding to the volume of a micropipet of a pipettor which is adapted to operatively engage the pipet, said volumetric increment being a minor proportion of the total internal volume of the pipet.

Claim 35

The method of claim 27 wherein the moveable walls of the suction and pressure lines include relatively moveable opposed wall portions, and wherein the respective opposed wall portions are moved in a plane perpendicular to the axis of their respecTive line.