US3650306A - Laboratory dispensing apparatus - Google Patents

Abstract

Laboratory dispensing apparatus including a base, a liquid reservoir and well assembly mounted on the base, and a microtitration plate carrier device mounted on the base for reciprocating movement between a forward retracted position and a rearward operative position overlying a portion of the well. A vertically movable pipette dispensing assembly is positioned above the base in operative alignment with the portion of the liquid well so that with the carrier in the forward retracted position the plural pipettes may withdraw microquantities of liquid from the well and then dispense the same into the microtitration plate wells when the carrier is moved to the rearward position. The plural pipettes are supported and contained in a head unit which is readily removable from the dispensing assembly to permit quick changing of heat units for cleaning purposes. A liquid agitator assembly is associated with the liquid reservoir and well assembly to circulate and stir the liquid and thereby insure uniformity and homogeneity of the liquid being dispensed by the plural number of pipettes. An electrical and pneumatic control system operates the stirring assembly and dispensing assembly, with the various control elements and components being mounted within the base structure of the dispensing apparatus to provide a compact self-contained portable system.

Description

United States Patent Lancaster [451 Mar. 21, 1972 [54] LABORATORY DISPENSING APPARATUS [72] Inventor:

[73] Assignee:

Jesse F. Lancaster, Great Falls, Va.

Cooke Engineering Company, Alexandria, Va.

[22] Filed: Sept. 18,1970

[2]] Appl.N0.: 73,505

52 U.S.Cl ..141/23s,23 259,141/242,

222/263, 259/1310. 46 51 Int. Cl. ..B65b3/30, BOlj 4/02 58 FieldofSearch ..141/8,18,21,25,20.5,3l,

141/59, 67, 115, 129,130, 181, 183, 234, 237, 238, 242, 392; 73/429.4 R, 429.6; 23/253, 259; 222/299, 196, 263, 275, 334, 335, 205, 183, 130; 259/D1G.

Primary ExaminerHouston S. Bell, .lr. Attorney-Strauch, Nolan, Neale, Nies & Kurz [57] ABSTRACT Laboratory dispensing apparatus including a base, a liquid reservoir and well assembly mounted on the base, and a microtitration plate carrier device mounted on the base-for reciprocating movement between a forward retracted position and a rearward operative position overlying a portion of the well. A vertically movable pipette dispensing assembly is posi- ,tioned above the base in operative alignment with the portion of the liquid well so that with the carrier in the forward retracted position the plural pipettes may withdraw microquantities of liquid from the well and then dispense the same into the microtitration plate wells when the carrier is moved to the rearward position. The plural pipettes are supported and contained in a head unit which is readily removable from the dispensing assembly to permit quick changing of heat units for cleaning purposes.

A liquid agitator assembly is associated with the liquid reservoir and well assembly to circulate and stir the liquid and thereby insure uniformity and homogeneity of the liquid being dispensed by the plural number of pipettes. An electrical and pneumatic control system operates the stirring assembly and dispensing assembly, with the various control elements and components being mounted within the base structure of the dispensing apparatus to provide a compact self-contained portable system.

18 Claims, 10 Drawing Figures Patented March 21, 1972 3,650,306

7 Sheets-Sheet 1 INVENTOR F JESSE F. LANCASTER ATTORN 5 Patented March 21, 1972 3,650,306

7 Sheets-Sheet 2 FIG. 2

INVENTOR JESSE F. LANCASTER Patented March 21, 1972 7 Sheets-Sheet 5 IN VENTOR JESSE F. LANCASTER Patented March 21, 1972 7 Sheets-Sheet 4 INVENTOR JESSE F. LANCAST ER ATTO EYS Patented March 21, 1972 7 Sheets-Sheet 5 INVENTOR JESSE F. LANCASTER E wfldzad ORNEY Patented March 21, 1972 3,650,306

'7 Sheets-Sheet 7 I I I I I I INVENTOR 7 JESSE F. LANCASTER BY 4 I LABORATORY DISPENSING APPARATUS BACKGROUND of THE INVENTION This invention is related generally to laboratory analyzing and titrating apparatus and more particularly to an automatic sampling and dispensing apparatus capable of precisely and simultaneously withdrawing into a plurality of needles or pipettes predetermined reproducible microquantities of liquid from a liquid source and delivering the same to a plurality of corresponding wells of a microtitration plate.

In the laboratory, quite often it is necessary to perform analytical and/or experimental tests or procedures on a large number of laboratory specimens, the procedures frequently involving the measuring and dispensing of microquantities of liquid in the nature of 25 microliters. It is, of course, desirable that such procedures be performed within a minimum amount of time and with extreme accuracy and precision to eliminate error.

In the past, laboratory tests of this nature have usually been performed manually and individually and have required a great deal of time and produced questionable results. The operator simply could not, time after time, reproduce with accuracy the microquantitative liquid measurements necessary for these tests, nor could he perform an adequate number of tests within a reasonable period of time.

Automatic laboratory devices have been developed in attempting to overcome these problems and one such device which was quite successful is described in my copending U.S. Pat. application Ser. No. 740,289 filed on June 26, 1968, now U.S. Pat. No. 3,568,735. While the apparatus disclosed in application Ser. No. 740,289, now U.S. Pat. No. 3,568,735 represented a significant improvement over prior conventional devices, it was not entirely satisfactory from several standpoints. For example, when the apparatus was used with liquids consisting of two different constituents, such as a saline solution, no provision was made in the apparatus to maintain uniform characteristics of the liquid so that all the microquantities of the liquid dispensed are the same. Also, each of the dispensing pipettes was individually mounted in the pipette dispensing assembly, thus requiring a great deal of time and labor in removing each pipette for cleaning or replacement purposes. In addition, the components of the electrical and pneumatic control systems were mounted separate from the dispensing apparatus itself, which as a result was not as compact as desired.

Accordingly, while this invention includes several of the unique features of the apparatus disclosed in Application Ser. No. 740,289, now U.S. Pat. No. 3,568,735 it is intended to be an improvement thereover and includes various novel features which contribute significantly to a more reliable, more practical and more compact dispensing apparatus.

SUMMARY OF THE INVENTION A primary object of the invention resides in the provision of a novel, more compact, self-contained laboratory dispensing apparatus capable of reliable use with any type liquid and functioning to simultaneously withdraw from a liquid reservoir into each of a plurality of needles or pipettes a predetermined reproducible microquantity of liquid, for example, a drop of 25 microliters, and simultaneously dispense the same into corresponding specimen containers or wells of a microtitration plate.

Another object of the invention resides in the provision of a more compact, self-contained laboratory dispensing apparatus in which the liquid supply source is readily mounted as part of the apparatus and liquid agitating means stirs and circulates the liquid to ensure that it is uniform and homogeneous throughout, thereby ensuring that the plural number of pipettes withdraw precise microquantities of liquid identical in characteristics and dispense the same into the associated microtitration plate wells.

Still another object resides in the provision of a novel, more compact, and self-contained laboratory dispensing apparatus in which the electrical and pneumatic control components for automatically controlling a dispensing operation are mounted within the base section of the apparatus as an integral part of the system thereby producing a readily portable apparatus which is easier to handle and conserves laboratory space.

A further object resides in the provision of a novel pickup and dispensing assembly including a pipette head unit having a plurality of needles or pipettes mounted therein, with the pipette head unit being readily removable from the dispensing assembly to permit quick simultaneous replacement of all the pipettes, or simultaneous cleaning thereof in a device such as an autoclave.

A still further object of the invention resides in the provision of a novel, vacuum-operated pneumatic control system for actuating the dispensing assembly to simultaneously control the pickup and dispensing of liquid from the plurality of pipettes and for accurately and precisely determining the exact microquantities of fluid which are to be picked up and dispensed.

Still other objects and advantages of the invention will become more apparent from reading the following detailed description of the invention as it proceeds with reference to the accompanying drawings in which like numerals indicate like elements. However, it is understood that the described embodiment is for illustrative purposes only, and that the scope of the invention is to be determined and limited solely by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a general perspective view of the novel laboratory dispensing apparatus of the invention;

FIG. 2 is a fragmentary, partially sectioned front elevation view of the laboratory dispensing apparatus shown in FIG. 1 and particularly illustrating the base construction of the apparatus;

FIG. 3 is a fragmentary, partially sectioned view taken generally along line 33 of FIG. 2 and illustrating particularly the manner in which several of the electrical and pneumatic control components and indicators and the liquid stirring device are mounted within the base structure;

FIG. 4 is a fragmentary, partially sectioned plan view taken generally along line 4-4 of FIG. 2 with the upper bed plate removed and illustrating the general positions in which the various electrical and pneumatic control components are mounted on the lower base plate of the laboratory dispensing apparatus;

FIG. 5 is a top plan view of the liquid reservoir base and bottle receiver forming a part of the invention;

FIG. 6 is a sectional elevation view taken generally along line 6-6 of FIG. 5;

FIG. 7 is an enlarged fragmentary, partially sectioned view of the novel pickup and dispensing assembly which forms part of the invention;

FIG. 8 is a fragmentary, partially sectioned side elevation view of the dispenser unit shown in FIG. 7;

FIG. 9 is an enlarged fragmentary, partially sectioned view of an individual pipette illustrating the manner in which it is mounted within the dispensing assembly; and

FIG. 10 is a schematic diagram of the electrical and pneumatic control systems by which the laboratory dispensing apparatus is automatically operated.

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, the novel automatic pickup and dispensingapparatus 20 comprises abase assembly 22 having an upper, Bakelite mounting bed-plate 24 covered by a thindecorative brass plate 25, and a pickup and dispensingpipette assembly 26 which includes a plurality ofpipettes 27. Theassembly 26 is mounted above bed-plate 24 viavertical post 28,control gear housing 30,gear rack 32 mounted withinhousing 30 and driven by a suitable pinion withinhousing 30 byhandle 34, and L-bracket 36 fixed to the lower end ofrack 32 and the rear end of dispensingassembly 26 viascrews 38. The pickup anddispensing assembly 26 is moved vertically relative to the mounting bed-plate 24 by rotatinghandle 34 to drive therack 32 up and down.

Asample carrier plate 40 is slidably mounted within longitudinal recesses provided inguide rails 42 and 44 which are spaced above the bed-plate 24 byspacers 46 secured to the bed-plate.Carrier plate 40 has a readilyaccessible knob 48 by which an operator may slide the plate from its forward retracted position shown in FIG. 1 to a rearward operational position in which the plate underlies thedispensing assembly 26.

Carrier plate 40 may support a plurality of separate vials or tubes or may preferably support atransparent microtitration plate 50 having a plurality ofwells 52 corresponding to the number ofpipettes 27 in thedispensing assembly 26. Themicrotitration plate 50 may be located oncarrier 40 via a titration plate locator and guide assembly (not shown) similar to that disclosed in application Ser. No. 740,289. The use of such a locator assembly enables an operator to readily replace one titration plate for another and ensures that thewells 52 of eachplate 50 will be accurately aligned with their respectivecorresponding pipettes 27 during a dispensing operation.

Mounted across the rear portion of mountingbed 24 is a clear acrylic, liquid reservoir plate 54 (FIGS. and 6) which is positioned on bed-plate 24 by anend recess 56 that engages aguide pin 58 extending upwardly from bed-plate 24 and by a lockingpin 60 which extends downwardly throughrail 44 into a blind hole 62 provided in the top surface ofreservoir plate 54.Reservoir plate 54 has a cylindrical recess or well 64 communicating with aliquid supply trough 66 located underneath thedispenser assembly 26 via a pair ofchannels 68 and 70 arranged substantially tangentially to the outer periphery ofcylindrical recess 64 to provide for recirculation of the liquid betweenrecess 64 andtrough 66 by an agitating device described below. Anotherpassage 72 extends diagonally between the supply passage 68 andtrough 66 to ensure that the liquid at the center oftrough 66 remains in an agitated state. A liquid reservoir tank orbottle 74 is mounted in an inverted state abovecylindrical recess 64 viabottle receiver 76 having a central opening 77, thereceiver 76 being fixed to the upper surface ofreservoir plate 54 byscrews 78.

A permanentmagnet bar stirrer 80 is supported on the bottom ofrecess 64 via anon-friction bearing stud 82 and is rotated by the magnetic drive assembly 90 (FIGS. 2-4) to circulate the liquid fromrecess 64 through channel 68 intotrough 66 and then back throughchannel 70 to recess 64. A portion of the liquid from channel 68 passes throughchannel 72 toward the center oftrough 66 to ensure that all the liquid intrough 66 remains agitated and prevents any occurrence of dead spots within the trough.

Referring now particularly to FIGS. 2-4, thebase assembly 22 also includes alower base plate 84 supported from a table or other suitable support by mountingpads 86, with the mounting bed-plate 24 being spaced abovebase plate 84 and supported thereon byvertical posts 88. The various electrical and pneumatic control components, which will be described later with respect to a typical dispensing operation, and the agitatormagnetic drive assembly 90 are supported onbase plate 84 within the confines of an annular shroud or covermember 92 connected at its upper end to the peripheral edge of mountingbed 24.

Mountingbed 24 has an elongated slottedopening 93 estending along one side thereof. Theagitator drive assembly 90 includes amotor 94 mounted onbase plate 84 for rotating a suitable holder for apermanent bar magnet 96 which is positioned withinslot 92 under thebrass plate 25 directly beneath thecylindrical recess 64 ofreservoir plate 54. As thedrive magnet 96 is rotated,stirrer magnet 80 inrecess 64 will followmagnet 96 and will thereby circulate the fluid betweenrecess 64 and through 66 to ensure that the liquid, for example a saline solution, will be of uniform and homogeneous composition at all times.

Referring now particularly to FIGS. 1 and 7-9, the dispensingassembly 26 includes anupper manifold plate 100, apiston guide plate 102 secured to manifold viascrews 104, and a removable dropper orpipette head unit 106 which includes adropper plate 108 and a dropperspring retainer plate 110 secured to plate 108 viascrews 112. Thedropper head unit 106 which supports all thepipettes 27 as a removable, self-contained unit is removably clamped tomanifold 100 and guideplate 102 by a pair of side clamps 114 and 116, each of which has ahorizontal lip 118 engaging the bottom side edges ofretainer plate 110. As shown best in FIGS. 1 and 7, a pair of adjustingjack screws 120 is connected to eachclamp 114 and 116. Each jack screw has an upper, large-diametercylindrical portion 122 which is slidable within anopening 124 inmanifold 100 and a reduceddiameter portion 126 which extends through a complimentary hold inguide plate 102, with the lower end ofsection 126 being threaded through a mating threaded opening inclamp 114 or 116. Acompressed spring 128 surroundsscrew section 126 of each of the adjusting screws in position between the opposed faces ofguide plate 102 and clamps 114 and 116. A lockingcam 130 is pivotally supported between the upper ends of each cooperating pair ofjack screws 120 on apin 132 which extends between the screws and is retained thereon by snap rings 134. Awasher 136 surrounds each of thescrews 120 in resting engagement with the top surface ofmanifold 100, and each of the lockingcams 130 includes a lockingcam surface 138 which, when engaged withwasher 136 as shown in FIG. 7, fastens thedropper unit 106 in operative relation tomanifold 100 and guideplate 102. When the lockingcams 130 are pivoted to an upright position,jack screws 120 will slide downwardly relative tomanifold 100 andplate 102 and thereby cause theclamps 114 and 116 anddropper unit 106 to be lowered to a release position (shown in phantom lines in FIG. 7) in which theentire unit 106 may be removed simply by sliding the unit forwardly over the retaininglips 118. Thedropper unit 106 is properly positioned in place during operation of the unit by abutment of the rear ends ofplates 108 and 110 against the bottom edge of thesupport bracket 36 as shown best in FIG. 8.

The dispenser assembly is operated by a vacuum source and, to accomplish this, the manifold 100 includes ahorizontal passageway 140 extending through one side face of the manifold and avertical passageway 142 intersecting and depending downwardly frompassage 140 through the bottom face ofmanifold 100. The outer end ofpassage 140 is connected to a vacuum source by way ofconduit 144 and a suitable threadedcoupling 146.

Piston plate 102 has an uppermost rectangularannular recess 148 which receives a sealinggasket 150 providing a seal between the opposed faces ofmanifold 100 andplate 102.Plate 102 also has an enlarged centralrectangular recess 152 communicating withpassage 142, withrecess 152 being intersected by a plurality ofbores 154 which open through the bottom face ofplate 102. In the embodiment illustrated, there are 96bores 154 corresponding in number to the 96 pipettes 27.

Apiston 156 is slidably received in each ofbores 154 and is biased downwardly by aspring 158. A thinflexible diaphragm 160 is positioned between the opposing faces of thepiston guide plate 102 and thedropper plate 108 when thedropper assembly 106 is positively fastened toplate 102. In such a position,diaphragm 160 closes the bottom ends ofbores 154 and thereby separates bores 154 from alignedopenings 162 provided through the upper face ofdropper plate 108 which also has an enlarged rectangularbottom recess 164. The dropperspring retainer plate 110 closes the bottom ofrecess 164 and itself includes a plurality ofopenings 166 which are aligned withopenings 162 and bores 154.

Each of the actuating pistons and the corresponding pipettes is identical to that illustrated in FIG. 9 and therefore only one piston and its actuating effect on its associatedpipette 27 will be described. Thepistons 156 include an upperannular flange section 168 adapted to seat on the bottom ofrecess 152 aroundbore 154. A reduceddiameter piston section 170 is loosely received withinbore 154 to provide a clearance therebetween andspring 158 is received within an axial blind bore 172 to normally bias thepiston 156 downwardly so that its bottom end firmly engages the upper side of thediaphragm 160.

Eachpipette 27 includes a largetubular section 174 having at its upper end anenlarged diameter section 176 which is slidable but closely fitted within opening 162 ofdropper plate 108. The upper end ofsection 176 is formed with anannular flange 178 which defines anupper recess 180 communicating with the central passageway 182 oftubular section 174. The lower end ofsection 176 is formed with ashoulder 184, and acompressed spring 186 acts betweenshoulder 184 and the upper face of the spring retainer plate 1 12 to bias thedropper 27 upwardly so that theannular flange 178 se'alingly engages the underside ofdiaphragm 160. The lower end oftubular section 174 extends outwardly throughopening 166 ofplate 110 and has a reduceddiameter tubular stem 188 press-fitted within its bottom end in flow communication with the passage 182.

in operation, when a vacuum is applied throughpassages 140 and 142 to recess 152,piston 168 will be moved upwardly withinbore 154 and the vacuum will be applied to the top ofdiaphragm 160, which then will be retracted withinbore 154. As a result, a suction effect will be created withinrecess 180 and passage 182 ofpipette 27 and, if the bottom end of thepipette stem 188 is immersed in the liquid intrough 66, a predetermined quantity of the liquid will be sucked into the pipette.

The actuating pressure acting ondiaphragm 160, in addition to being set by the pneumatic control components described hereinbelow, is determined by properly adjustingjack screws 120 to set the clamping force applied byclaims 114 and 116 to hold thepipette head unit 106 againstdiaphragm 160 andplate 102. For example,jack screws 120 may be adjusted to provide approximately 7 to 10 pounds actuating pressure with the head unit in place.

It should be especially noted that each of thepipettes 27 is permanently mounted within thedropper unit 106 so long as theplates 108 and 110 are maintained in assembled relationship. Whenunit 106 is to be removed frommanifold 100 and guideplate 102 by releasing the lockingcams 130 and clamps 114 and 116, theannular shoulder 184 of each of the pipettes will engage the wall surfaces ofdropper plate 108 surrounding theopenings 162 and thereby maintain the pipettes in assembled relationship betweenplates 108 and 110. Consequently, theentire dropper unit 106 may be removed and placed in a device such as an autoclave for simultaneously cleaning all the pipettes together without having to disturb the individual mounting or assemblage of each individual pipette.

A typical pickup and dispensing operation will now be described with special reference to FIGS. 1 to 4 and 10, with FIG. 4 generally illustrating the position of the various electrical and pneumatic control components as they are mounted on thebase plate 84 enclosed withinshroud 92, and FIG. 10

' schematically illustrating the electrical and pneumatic connections to the various components.Flexible conduit 144 extends frommanifold 100 downwardly through suitable openings in the decorative coverplate 25 and mountingbed 24 withinshroud 92 and is connected to a solenoid operatedvalve 188.Valve 188 is connected to a suitable vacuum source viavacuum gauge 190 andconduit 192 which has acoupling end 194 extending outwardly through aslot 196 provided in the rear wall ofannular shroud 92. The head ofvacuum gauge 190 is positioned so as to lie within theelongated slot 93 of mountingbed 24 anddecorative plate 25 has a suitable opening and protective transparent cover through which thegauge 190 may be read by an operator as illustrated in FIG. 1. It should be noted that thevalve 188,gauge 190, and connecting conduits are all supported onbase plate 84 within theannular shroud 92.

The electrical operating circuit for the dispensing apparatus includes an on-off switch 196 and indicator light 198 mounted on the top ofdecorative plate 25 and a foot operatedswitch 200 conveniently located for use by an operator. The main electrical system of the apparatus includes aterminal board 202 having contacts C1, C2, C3, C4, C5 and C6, withterminal board 202 being mounted on the top ofbase plate 84. A threewireelectrical conductor 204 has its ground lead connected to contacts C1 and itsother leads 208 and 210 connected to contacts C2 and C3, respectively. The electrical system also includes atransformer 212 for reducing the supply voltage of either 1 10 volts or 220 volts to a predetermined control voltage used to operate the agitatingmotor 94 and the other components of the control system. Thetransformer 212 has anoutput terminal board 214 having contacts A, B and C, with contact B being a ground terminal connected to ground contact C1 ofterminal board 202 by aconductor 216 and to amachine ground 218 by aconductor 220.

To use the apparatus, an operator will initiallyclose switch 196 to pass current from contact C2 throughlines 222 and 224,fuse 226,line 228, the appropriate contacts of aslide switch 230 to the primary side T1 oftransformer 212.Slide switch 230 is of a conventional type by which either 1 10 volts or 220 volts can be supplied to the primary side T1 oftransformer 212. Current will then be supplied from the secondary side T2 oftransformer 212 to the output terminals A, B and C ofterminal board 214. Current then flows from terminal C ofboard 214 to the agitatingdrive motor 94 viaconductor 232,

contacts C4 ofboard 202,conductor 236 throughmotor 94 toconductor 238,resistor 240,potentiometer 242, andconductor 244 back to contact C5 ofboard 202. The speed ofmotor 94 may be adjusted by proper adjustment ofpotentiometer 242 to vary the speed of rotation ofdrive magnet 96 andfollower magnet 80 withinrecess 64. ln this way, the rate of circulation of the liquid inreservoir 54 may be properly adjusted. Following closure ofswitch 196, theindicator lamp 198 will be lighted as current flows from contact C4 through the lamp and back to contact C5 ofboard 202 and contact A ofboard 214 viaconductor 246. Thus, the operator is informed of proper operation of the system by the lighting oflamp 198.

With the agitatingdrive system 90 continually operating and the liquid being circulated betweenrecess 64 andtrough 66 to ensure uniformity of the characteristics of the liquid, the operator may then effect a dispensing operation as follows.

' With thecarrier 40 and microtitration plate in its inoperative retracted position shown in FIG. 1, the dispensingassembly 26 may be lowered by rotation ofhandle 34 until the open ends ofpipettes 27 are immersed in the liquid intrough 66. The operator then depresses the foot operatedswitch 200 which causes current to flow from contact C4 through theclosed switch 200 to contact C6, throughconductor 248 to theoperating solenoid 250 ofvalve 188, and back to contact C5 viaconductor 252. Energization ofsolenoid 250 will openvalve 188 to thereby connectconduit 144 to the vacuum inconduit 192.

This vacuum will then be applied through the passages and 142 ofmanifold 100 to the enlargedguide plate recess 152 which acts as a vacuum chamber.Pistons 156 will be raised within theirrespective bores 154 and the vacuum will then be applied to the top ofdiaphragm 160 which will be retracted within thebores 154. Consequently, a suction will be created within each of thepipettes 27 and a predetermined amount of liquid will be withdrawn into the tubular passageways of each pipette. While still holding the foot operatedswitch 200 depressed to continue application of the vacuum tomanifold 100, the operator will then raise the dispensingassembly 26 out oftrough 66 and thereafter slidecarrier plate 40 along guide tracks 42 and 44 to its rearward operative position in which it overliestrough 66 and in which thewells 52 ofmicrotitration plate 50 are accurately aligned with respective ones ofpipettes 27. Dispensingassembly 26 is again lowered so that each of thepipettes 27 is positioned within an aligned well 52 ofplate 50. The operator then releases foot-operatedswitch 200 todeenergize solenoid 250 andclose valve 188 to disconnectconduit 144 fromconduit 192.Valve 188 includes a conventional means (not shown) which, when the valve is in the closed position, will automatically ventconduit 144 to atmosphere. Thus, whenvalve 188 is closed, atmospheric pressure will again be applied tomanifold 100 throughconduit 144 to thereby causepistons 156 anddiaphragm 160 to be biased downwardly bysprings 158. Downward movement ofdiaphragm 160 will cause the liquid in each of thepipettes 27 to be simultaneously expelled from the pipettes intowells 52 ofmicrotitration plate 50.

The dispensingassembly 26 is then raised to its uppermost position andcarrier 40 returned to its forward retracted position in whichmicrotitration plate 50 may be readily removed and another plate placed on thecarrier 40 for the next dispensing operation.

From the above description, it is apparent that the laboratory dispensing apparatus of the invention accomplishes the objects and provides the advantages initially set forth by providing a device which is highly reliable and accurate in simultaneously dispensing reproduceable microquantities of liquid; is compact and self-contained and therefore readily portable and manipulatable; is adapted for usage with various type liquids including those having several constituents; and is easily cleaned when necessary due to the fact that the dispenser head unit supporting the plural number of pipettes is quickly and easily removed from the apparatus for placement in a device such as an autoclave.

It is understood of course, that various other modifications and embodiments are encompassed within the scope of the invention which, of course, is not limited by the detailed description above. For example, when used with some liquids, it may be necessary to provide a suitable coating on the external surfaces of the pipettes to prevent any adherence of the liquid thereto which might adversely affect the accuracy of the microquantities of liquid being dispensed.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent 1. Dispensing apparatus comprising a base section, liquid reservoir means on said base section for containing a liquid to be dispensed, agitator means associated with said reservoir means pick up the liquid therein, carrier means mounted on said base section for horizontal movement between a first nondispensing position at one side of said liquid reservoir means and a second dispensing position in which said carrier means overlies a portion of said liquid reservoir means, liquid receptacle means supported on said carrier means, pick up and dispensing means mounted on said base section in operative alignment above said portion of said reservoir means, means for moving said pick up and dispensing means vertically relative to said base section, whereby, when said carrier means is in said first position, said pick up and dispensing means may be lowered to a first position to withdraw liquid from said portion of said reservoir means, then raised to permit said carrier means to be placed in said second position, and then lowered to a second position to dispense the withdrawn liquid into said receptacle means.

2. Dispensing apparatus as in claim 1, said liquid reservoir means comprising a trough positioned underneath said pick up and dispensing means, a liquid supply well remote from said trough and communicating therewith through connecting channel means, and said agitator means causing agitation of the liquid in said trough.

3. Dispensing apparatus as in claim 2, wherein said channel means comprises a pair of channels connecting said supply well with said trough, and said agitator means causes recirculation of the liquid between said supply well and said trough via said channels.

4. Dispensing apparatus as in claim 3, said agitator means comprising a permanent magnet rotatably mounted in said supply well for stirring said liquid, a drive assembly for said magnet including motor means mounted on said base section, a drive magnet rotated by said motor means, said drive magnet being operatively associated with said stirring magnet to rotate the same upon actuation of said motor means.

5. Dispensing apparatus as in claim 4, wherein said pair of channels extends substantially tangentially from the outer periphery of said supply well to the outer portions of said trough, and another channel intersects and extends from the inlet one of said pair of channels toward the central section of said trough to ensure that all of the liquid in said trough is agitated.

6. Dispensing apparatus as in claim 1, wherein said agitator means comprises a permanent magnet rotatably mounted in said liquid reservoir means for stirring said liquid, a drive assembly for said stirring magnet including motor means mounted on said base section, a drive magnet rotated by said motor means, said drive magnet being operatively associated with said stirring magnet to rotate the same upon actuation of said motor means.

7. Dispensing apparatus as in claim 1, wherein said base section includes a lower base plate and an upper mounting bedplate supported above said base plate, said liquid reservoir means, said carrier means, and said pick up and dispensing means being mounted on said upper mounting bed-plate, said mounting bed-plate having an elongated slot at least part of which extends underneath said reservoir means, said agitator means comprising a permanent magnet rotatably mounted in said reservoir means for stirring the liquid therein, motor means mounted on said lower base plate, a drive magnet rotated by said motor means and positioned within said slot of said reservoir means, said drive magnet being operatively associated with said stirrer magnet to rotate the same upon actuation of said motor means.

8. Dispensing apparatus as in claim 7, comprising an electrical control system for said agitator motor means, a pneumatic control system for operating said pick up and dispensing means, and at least some of the components of said electrical and pneumatic control systems being mounted on said base plate, thereby providing a compact, self-contained dispensing apparatus.

9. Dispensing apparatus as in claim 1, said pick up and dispensing means comprising manifold means, a pipette head unit including a plurality of dispensing pipettes normally retained in assembled relationship in said head unit, means for removably connecting said pipette head unit to said manifold means, flexible diaphragm means operatively positioned between said manifold means and said pipette unit, said manifold means having air passage means leading to one side of said diaphragm means, and a pneumatic supply system connected to said air passage means for creating a differential pressure on opposite sides of said diaphragm means to simultaneously pick up predetermined quantities of liquid from said reservoir means into said pipettes and thereafter simultaneously dispense said quantities from said pipettes.

10. Dispensing apparatus as in claim 9, said manifold means comprising a manifold having an air passageway, an actuating guide plate connected to said manifold and having a plurality of apertures communicating at one end with said manifold air passageway and terminating at their other ends at said one side of said diaphragm means, piston means mounted in each of said apertures and normally biased into engagement with said one side of said diaphragm means, said pipette head unit being removably connected to said manifold and piston guide plate, with each pipette being operatively aligned on the other side of said diaphragm means with a corresponding piston.

11. Dispensing apparatus as inclaim 10, said pipette head unit comprising a dropper plate having a plurality of openings which operatively align with said piston guide plate apertures, a retainer plate connected to said dropper plate and having openings aligning with said dropper plate openings, each of said pipettes having an enlarged diameter section at one end slidably received within one of said dropper plate openings and a smaller diameter section extending outwardly through the aligned retainer plate opening, and spring means biasing said enlarged diameter section into engagement with the other side of said diaphragm means in operative alignment with one of said pistons.

12. Dispensing apparatus as inclaim 10, said means for removably connecting said pipette head unit to said manifold means comprising clamp means for supporting said head unit, shaft means slidably extending through said manifold and piston guide plate and fixed at one end to said clamp means, locking means connected to the other end of said shaft means and movable between locked and unlocked positions,-

whereby when said locking means is in said locked position said head unit is operatively clamped to said manifold and said piston guide plate, and when said locking means is in said unlocked position said head unit is unclamped and may be readily removed from said pick up and dispensing means.

13. Dispensing apparatus as in claim 12, wherein said shaft means is adjustable screw means adjustably connected to said clamp means so that the effective actuating pressure acting on said diaphragm means may be varied by adjustment of said screw means.

14. Dispensing apparatus as in claim 9, wherein said pneumatic supply system includes a vacuum source.

15. Dispensing apparatus comprising a base section including a lower base plate and an upper mounting bed-plate supported above said base plate; liquid reservoir means on said mounting bed-plate for containing a liquid to be dispensed, said reservoir means including a trough and a liquid supply well remote from said trough and connected therewith through connecting channel means; liquid agitator means comprising a permanent stirring magnet rotatably mounted in said reservoir means, motor means mounted on said lower base plate, a drive magnet rotated by said motor means and operatively associated with said stirring magnet to rotate the same upon actuation of said motor means; carrier means mounted on said mounting bed-plate for movement between a first non-dispensing position at one side of said trough and a second dispensing position in which said carrier means overlies said trough; liquidreceptacle means supported on said carrier means; pick up and dispensing means mounted for vertical movement on said bed-plate in operative alignment above said trough, said pick up and dispensing means comprising manifold means, a pipette head unit including a plurality of dispensing pipettes normally retained in assembled relationship in said head unit, means for removably connecting said pipette head unit to said manifold means, flexible diaphragm means operatively positioned between said manifold means and pipette head unit, said manifold means having air passage means leading to one side of said diaphragm means; a pneumatic control system connected to said air passage means for creating a differential pressure on opposite sides of said diaphragm means to permit simultaneous pick up of predetermined quantities of liquid from said trough when said carrier means is in said first non-dispensing position and then dispensing of said predetermined quantities of liquid from said pipettes into said liquid receptacle means when said carrier means is in said second dispensing position; an electrical control system for said agitator motor means; and at least some of the components of said pneumatic control system and said electrical control system being mounted on said lower base plate to provide a compact, self-contained dispensing apparatus.

16. Dispensing apparatus as in claim 15, said pneumatic control system comprising an air supply source, a solenoidoperated air valve mounted on said lower base plate and connected between said supply source and said air passage means in said manifold means, manually o erated electrical switch means connected to said air solenoi valve means for operating said valve means, said switch means being accessible to an operator, and a pressure indicator means mounted on said base plate and extending through said mounting bed-plate so as to be readily visible by an operator.

l7. Dispensing apparatus as in claim 16, said electrical control system comprising an electrical supply source, a transformer mounted on said base plate, second switch means connecting the primary side of said transformer to said electrical supply source, said second switch means being mounted above said bed-plate for ready access by an operator, first circuit means connecting the secondary side of said transformer to said agitator motor means and including a variable resistance mounted on said lower base plate for varying the speed of said motor means, and second circuit means including an indicator lamp mounted above said bed plate and readily visible to an operator to indicate operation of the apparatus when said second switch means has been placed in an on position.

18. Dispensing apparatus as in claim 16, wherein said air supply source is a vacuum source and said indicator means is a vacuum gauge.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3, 650, 306 Dated March 21, 1972 InV nt Jesse F. Lancaster I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7,line 50, after "means" insert ---'-for agitating-- and delete "pick up" Signed and sealed this 12th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Commissioner of Patents Attesting Officer FORM uscoMM-Dc sows-ps9 LLS GOVERNMENT PRINTING OFFlCE; 959 3$5-334

Claims (18)

1. Dispensing apparatus comprising a base section, liquid reservoir means on said base section for containing a liquid to be dispensed, agitator means associated with said reservoir means pick up the liquid therein, carrier means mounted on said base section for horizontal movement between a first non-dispensing position at one side of said liquid reservoir means and a second dispensing position in which said carrier means overlies a portion of said liquid reservoir means, liquid receptacle means supported on said carrier means, pick up and dispensing means mounted on said base section in operative alignment above said portion of said reservoir means, means for moving said pick up and dispensing means vertically relative to said base section, whereby, when said carrier means is in said first position, said pick up and dispensing means may be lowered to a first position to withdraw liquid from said portion of said reservoir means, then raised to permit said carrier means to be placed in said second position, and then lowered to a second position to dispense the withdrawn liquid into said receptacle means.

2. Dispensing apparatus as in claim 1, said liquid reservoir means comprising a trough positioned underneath said pick up and dispensing means, a liquid supply well remote from said trough and communicating therewith through connecting channel means, and said agitator means causing agitation of the liquid in said trough.

3. Dispensing apparatus as in claim 2, wherein said channel means comprises a pair of channels connecting said supply well with said trough, and said agitator means causes recirculation of the liquid between said supply well and said trough via said channels.

4. Dispensing apparatus as in claim 3, said agitator means comprising a permanent magnet rotatably mounted in said supply well for stirring said liquid, a drive assembly for said magnet including motor means mounted on said base section, a drive magnet rotated by said motor means, said drive magnet being operatively associated with said stirring magnet to rotate the same upon actuation of said motor means.

5. Dispensing apparatus as in claim 4, wherein said pair of channels extends substantially tangentially from the outer periphery of said supply well to the outer portions of said trough, and another channel intersects and extends from the inlet one of said pair of channels toward the central section of said Trough to ensure that all of the liquid in said trough is agitated.

6. Dispensing apparatus as in claim 1, wherein said agitator means comprises a permanent magnet rotatably mounted in said liquid reservoir means for stirring said liquid, a drive assembly for said stirring magnet including motor means mounted on said base section, a drive magnet rotated by said motor means, said drive magnet being operatively associated with said stirring magnet to rotate the same upon actuation of said motor means.

7. Dispensing apparatus as in claim 1, wherein said base section includes a lower base plate and an upper mounting bed-plate supported above said base plate, said liquid reservoir means, said carrier means, and said pick up and dispensing means being mounted on said upper mounting bed-plate, said mounting bed-plate having an elongated slot at least part of which extends underneath said reservoir means, said agitator means comprising a permanent magnet rotatably mounted in said reservoir means for stirring the liquid therein, motor means mounted on said lower base plate, a drive magnet rotated by said motor means and positioned within said slot of said reservoir means, said drive magnet being operatively associated with said stirrer magnet to rotate the same upon actuation of said motor means.

8. Dispensing apparatus as in claim 7, comprising an electrical control system for said agitator motor means, a pneumatic control system for operating said pick up and dispensing means, and at least some of the components of said electrical and pneumatic control systems being mounted on said base plate, thereby providing a compact, self-contained dispensing apparatus.

9. Dispensing apparatus as in claim 1, said pick up and dispensing means comprising manifold means, a pipette head unit including a plurality of dispensing pipettes normally retained in assembled relationship in said head unit, means for removably connecting said pipette head unit to said manifold means, flexible diaphragm means operatively positioned between said manifold means and said pipette unit, said manifold means having air passage means leading to one side of said diaphragm means, and a pneumatic supply system connected to said air passage means for creating a differential pressure on opposite sides of said diaphragm means to simultaneously pick up predetermined quantities of liquid from said reservoir means into said pipettes and thereafter simultaneously dispense said quantities from said pipettes.

10. Dispensing apparatus as in claim 9, said manifold means comprising a manifold having an air passageway, an actuating guide plate connected to said manifold and having a plurality of apertures communicating at one end with said manifold air passageway and terminating at their other ends at said one side of said diaphragm means, piston means mounted in each of said apertures and normally biased into engagement with said one side of said diaphragm means, said pipette head unit being removably connected to said manifold and piston guide plate, with each pipette being operatively aligned on the other side of said diaphragm means with a corresponding piston.

11. Dispensing apparatus as in claim 10, said pipette head unit comprising a dropper plate having a plurality of openings which operatively align with said piston guide plate apertures, a retainer plate connected to said dropper plate and having openings aligning with said dropper plate openings, each of said pipettes having an enlarged diameter section at one end slidably received within one of said dropper plate openings and a smaller diameter section extending outwardly through the aligned retainer plate opening, and spring means biasing said enlarged diameter section into engagement with the other side of said diaphragm means in operative alignment with one of said pistons.

12. Dispensing apparatus as in claim 10, said means for removably connecting said pipette head unit to said manifold means comprising clamp means for supporting said head unit, shaft means slidably extending through said manifold and piston guide plate and fixed at one end to said clamp means, locking means connected to the other end of said shaft means and movable between locked and unlocked positions, whereby when said locking means is in said locked position said head unit is operatively clamped to said manifold and said piston guide plate, and when said locking means is in said unlocked position said head unit is unclamped and may be readily removed from said pick up and dispensing means.

13. Dispensing apparatus as in claim 12, wherein said shaft means is adjustable screw means adjustably connected to said clamp means so that the effective actuating pressure acting on said diaphragm means may be varied by adjustment of said screw means.

14. Dispensing apparatus as in claim 9, wherein said pneumatic supply system includes a vacuum source.

15. Dispensing apparatus comprising a base section including a lower base plate and an upper mounting bed-plate supported above said base plate; liquid reservoir means on said mounting bed-plate for containing a liquid to be dispensed, said reservoir means including a trough and a liquid supply well remote from said trough and connected therewith through connecting channel means; liquid agitator means comprising a permanent stirring magnet rotatably mounted in said reservoir means, motor means mounted on said lower base plate, a drive magnet rotated by said motor means and operatively associated with said stirring magnet to rotate the same upon actuation of said motor means; carrier means mounted on said mounting bed-plate for movement between a first non-dispensing position at one side of said trough and a second dispensing position in which said carrier means overlies said trough; liquid receptacle means supported on said carrier means; pick up and dispensing means mounted for vertical movement on said bed-plate in operative alignment above said trough, said pick up and dispensing means comprising manifold means, a pipette head unit including a plurality of dispensing pipettes normally retained in assembled relationship in said head unit, means for removably connecting said pipette head unit to said manifold means, flexible diaphragm means operatively positioned between said manifold means and pipette head unit, said manifold means having air passage means leading to one side of said diaphragm means; a pneumatic control system connected to said air passage means for creating a differential pressure on opposite sides of said diaphragm means to permit simultaneous pick up of predetermined quantities of liquid from said trough when said carrier means is in said first non-dispensing position and then dispensing of said predetermined quantities of liquid from said pipettes into said liquid receptacle means when said carrier means is in said second dispensing position; an electrical control system for said agitator motor means; and at least some of the components of said pneumatic control system and said electrical control system being mounted on said lower base plate to provide a compact, self-contained dispensing apparatus.

16. Dispensing apparatus as in claim 15, said pneumatic control system comprising an air supply source, a solenoid-operated air valve mounted on said lower base plate and connected between said supply source and said air passage means in said manifold means, manually operated electrical switch means connected to said air solenoid valve means for operating said valve means, said switch means being accessible to an operator, and a pressure indicator means mounted on said base plate and extending through said mounting bed-plate so as to be readily visible by an operator.

17. Dispensing apparatus as in claim 16, said electrical control system comprising an electrical supply source, a transformer mounted on said base plate, second switch means connecting the primary side of said transformer to said electrical supply source, said second switch means being mounted above said bed-plaTe for ready access by an operator, first circuit means connecting the secondary side of said transformer to said agitator motor means and including a variable resistance mounted on said lower base plate for varying the speed of said motor means, and second circuit means including an indicator lamp mounted above said bed plate and readily visible to an operator to indicate operation of the apparatus when said second switch means has been placed in an on position.

18. Dispensing apparatus as in claim 16, wherein said air supply source is a vacuum source and said indicator means is a vacuum gauge.

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