US3327535A

US3327535A - Multiple pipetting apparatus

Info

Publication number: US3327535A
Application number: US391436A
Authority: US
Inventors: Sequeira Peter Jam Littlejohns
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-08-24
Filing date: 1964-08-24
Publication date: 1967-06-27
Anticipated expiration: 1984-06-27
Also published as: DE1989602U; GB1014462A

Description

June 1957 P. J. L. SEQUEIRA MULTIPLE PIPETTING APPARATUS ll Sheets-Sheet 1 Filed Aug. 24, 1964 June 27, 1967 J, 1.. SEQUEIRA MULTIPLE PIPETTING APPARATUS ll Sheets-Sheet 2 Filed Aug. 24, 1964 flwiwwwww I M a 0 N NY; 7 Q HIH HHHHHI MIH HH I IHMW I I I |||\N.IIJ

1 I I I l I 1K l I I... lllllll@l I ll June 27, 1967 P, J. L. SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS Filed Aug. 24, 1964 ll Sheets-Sheet 3 I if I:- 55? 14 F/G.3C.

g /5 =IN {1:31 m if Q Q g m 52:11 K

- iiii i j J L 1% June 1967 P. J. L. SEQUEIRA MULTIPLE PIPETTING APPARATUS ll Sheets-Sheet 4 Filed Aug. 24, 1964 uuuwuupu II II II II H II II II II ooeoocoogfi bo wm wt June 27, 1967 R J SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS l1 Sheets-Sheet 5 Filed Aug. 24, 1964 MN NNKN June 1967 P. J. L. SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS Filed Aug. 24, 1964 ll Sheets-Sheet 8 June 27, 1967 P. J. L. SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS Filed Aug. 24, 1964 11 Sheets-Sheet 9 June 27, 1967 p, J. 1.. SEQUEIRA MULTIPLE PIPETTING APPARATUS ll Sheets-Sheet 10 Filed Aug. 24, 1964 FIG. 70.

June 27, 1967 P. J. L. SEQUEIRA 3,327,535 7 MULTIPLE PIPETTING APPARATUS m5 7400/ T K/Q96 L U United States Patent 3,327,535 MULTIPLE FIPETTING APPARATUS Peter James Littieiohns Sequeira, 23 Macclesfield Road, Wilmslow, Cheshire, England Filed Aug. 24, 1964, Ser. No. 391,436

Claims priority, application Great Britain, Aug. 24,1963,

33,611/63 14 Claims. (Cl. 73-423) This invention concerns a multiple pipetting apparatus adapted to dispense known proportions from each of a plurality of liquid samples into a plurality of receptacles.

According to the present invention a multiple pipetting apparatus comprises a base having a support for carrying receptacles arranged in rows extending along the support and in columns extending across the support, a member extending across the support and spaced above it, a mechanism for producing relative longitudinal movement between the support and the member, a line of pipetting tubes mounted on the member and individually communicating through pipes with respective piston-and-cylinder units operated in synchronism to draw liquid simultaneously into the pipetting tubes or expel liquid simultaneously from the pipetting tubes, and a device for raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles. Preferably the units comprise syringes.

Pipetting apparatus in accordance with the invention has the advantage that it enables routine pipetting such as is necessary for serological and biochemical work to be carried out more rapidly than is possible when done manually and with greater average accuracy.

Preferably the support is movable with respect to the base although it is not outside of the scope of the invention to have the support fixed to the base and the pipetting tubes movable lengthwise of the base.

Preferably the pipetting tubes are made of polytetrafluoroethylene as this substance is hydrophobic and there is little tendency for aqueous liquids to be retained on its surfaces and be carried from one receptacle to another during use and thus spoil the accuracy of the apparatus.

The invention will now be described in more detail, by way of examples, with reference to the accompanying drawings, in which:

FIGURE 1 shows, in side elevation, one form of apparatus;

FIGURES 2A, 2B and 2C are side elevations respectively of the front portion, intermediate portion, and rear portion of the apparatus of FIGURE 1 on an enlarged scale;

FIGURES 3A, 3B and 3C are respectively plan views of the three portions of the apparatus shown in FIG- URES 2A, 2B and 2C;

FIGURE 4 is a greatly simplified perspective view of an alternative form of multiple pipetting apparatus;

FIGURE 5 is a view corresponding to FIGURE 4 but with sections broken away to expose the interior of the apparatus and in particular a pulley system used to raise and lower a line of pipetting tubes;

FIGURE 6A is a perspective view, with parts broken away of a tray forming part of a support used in the apparatus of FIGURE 4;

FIGURE 6B is a perspective view with parts broken away of a carriage also forming part of the support;

FIGURE 6C is a perspective view with parts broken away of a rail, clamping pieces and T-piece, which may be used on the rail which forms part of the support;

FIGURE 7 is a scrap view of the apparatus of FIG- URE 4 and shows a handle and associated stops for limiting its movement;

FIGURE 8 shows schematically parts of the apparatus of FIGURE 4 and their interconnections;

FIGURE 9 illustrates a mechanism for drawing liquid into and expelling liquid from the pipetting tubes of FIGURE 4; and

FIGURE 10 is a sectional view of a mount used for supporting a pipetting tube in FIGURE 4; and

FIGURE 11 is an electrical circuit diagram.

The apparatus shown in FIGURES 1 to 3 is very suitable for serological work and is capable of being loaded with samples of serum, each of which is to be dispensed into a number of receptables in various predetermined proportions of dilution as will be explained hereafter. Whilst the apparatus may be loaded with many samples, it can dispense 10 of them simultaneously and in 4 complete cycles of operation can dispense all the samples with which the apparatus is loaded.

Referring now to FIGURE 1 it will be seen that the apparatus essentially comprises a base, generally indicated by the reference numeral 10, a carriage, generally indicated by the reference numeral 11, and a pipetting assembly, generally indicated by the reference numeral 12.

The base 10 is generally of channel cross-section, comprising a bottom member 13, and side walls 14, which extend beyond the bottom member 13 at the front end of the apparatus. The carriage 11 essentially comprises a rectilinear platform 15 which carries a number of rollers 16 on each of its longitudinally extending sides. The rollers 16 engage rails 17 provided on the upper edge of each of the side walls 14 of the base portion 10, in such a manner that the carriage 11 may be freely moved longitudinally over the base portion 10.

The carriage 11 provides a support for a multiplicity of removable receptacles for liquid, which will now be described. An aluminum frame 18 extends transversely over the rear end of the carriage 11, and is provided with forty holes 19, each of which is adapted to locate a test tube 29 for a sample of liquid which is to be dispensed by the apparatus. The forty holes 19 are arranged in four columns of 10, each of which extends transversely across the carriage 11. The frame 18 is followed by a frame 21, which is provided with forty holes 22 each of which is adapted to locate a test tube 23. The holes 22 in the frame 21 are arranged in a like manner to the holes 19 in the frame 18. The frame 21 is followed by a rectangular bath 24 which extends transversely over the entire width of the carriage. The bath 24 is intended to receive waste material as will be explained in greater detail hereinafter. The bath 24 is followed by a further bath 25 which likewise extends transversely over the entire width of the carriage. The bath 25 is adapted to hold a diluent for the samples which are to be dispensed by the apparatus. The bath 25 is followed by a plate 26, which is provided with eighty blind holes 27, each of which forms a receptacle for liquid. The eighty holes 27 are arranged in eight colums of ten, each of which extends transversely over the width of the carriage. The plate 26 is followed by a plate 28 which is provided with eighty blind holes 29 arranged in a like manner to the holes 27 in the plate 26.

The pipetting assembly 12 essentially comprises an L-shaped member having one limb formed by a tubular arm 39 pivotally mounted at its lower end to one of the side Walls 14 of the base portion 10. The arm 30 carries at its upper end a bar 31 forming the other limb of the L and extends transversely over the upper face of the carriage 11. The bar 31 supports ten pipetting tubes 32 which extend therefrom in spaced parallel relationship downwardly towards the upperface of the carriage 11.

The tubes 32 are formed from a polytetrafluoroethylene' material. Each pipetting tube 32 is connected to a pipe or tube 33 which extends from its upper end through the arm 30 and an aperture 34 in one of the side walls 14 of the base 10 to the interior of the channel-section of the base. Each tube 33 is connected to one of a set of syringes 35 disposed between the side walls 14 of the base. The ten syringes 35 extend longitudinally of the apparatus and are arranged in parallel spaced relationship in a line which extends transversely across the apparatus. The plungers 36 of the syringes 35 are all connected rigidly to a bar element 37 which is in turn connected to a toothed rack 38 at each of its ends. An axle 39 extends transversely of the apparatus and is carried in bearings mounted in each of the side walls 14. The axle 39 carries pinions 40 which are in engagement with the racks 38. One end of the axle 39 carries a radially directed handle 41 which is provided with releasable locking means 42 adapted to co-operate with a plurality of stops 43 mounted on an arcuate guide frame 44. Rotation of the handle 41 causes actuation of the plungers of the syringes 35 by means of the pinion-s 40, racks 38 and bar 37.

A device in the form of a handle 45 is provided for controlling the raising and lowering of the pipetting tubes 32 and also the longitudinal position of the carriage 11 on the base 10, in a manner which will now be described.

The handle 45 is rigidly secured to one end of an axle 46 which extends transversely of the carriage at a position adjacent the front end thereof. A short arm 47 is firmly secured to the axle 46 and projects downwardly therefrom, its lower end being connected with the underside of the carriage 11 by a tension spring 48. The arm 47 carries a freely rotatable pulley 49 around which passes a wire or cord 50. One side of the cord 56 extends backwardly from the pulley 49 to a further pulley 51. freely and rotatably mounted at the rear end of the carriage 11. The cord passes round the pulley 51 and forwardly to a position beneath the pipetting tubes 32 where it is firmly secured to a bracket 52. The other side of the cord 50 extends rearwardly from the pulley 49 to a pulley 53 mounted on one of the side walls 14. The cord 50 passes round the pulley 53 and through a small aperture 54 in the side wall and round a further pulley 55 freely mounted on the outside of the side wall 14, whence it extends to the end of a lever 56 connected with the arm 30 at the position where the latter ispivoted t the wall 14.

The side of the platform 15 constituting the carriage 11 adjacent the arm 30 is provided with a side wall 57, whose upper edge defines a cam surface 58 provided with a slot or notch 59 transversely opposite each transversely extending row of

receptacles

20, 23, 24, 25, 27 or 28. A rod 60 is pivotally connected to the lever 56 by its rear end, and is pivotally connected to a bell crank lever consisting of arms 61 and 62 at its front end. The upper end of the arm 61 carries an interlock pin or peg 63 which is adapted to rest either on the cam surface 58 provided by the wall 57 or in one of the slots or notches 59.

When the handle 45 is rotated, the cord 50 moves in such a manner as to operate on the lever 56 as to pull same forwardly and cause the

arms

30 and 61 to rise, whereby the lower ends of the pipetting tubes 32 are removed to a position wherein they are spaced from the receptacles supported by the carriage 11, and whereby the pin 63 is moved to a position wherein it disengages with the notches 59 and the cam surface 58. When the

arms

30 and 61 are in their raised position, the handle 45 may be used to pull the carriage forwardly or to push same rearwardly. The carriage may be halted in any desired position and the handle 45 released so as to allow the

arms

30 and 61 to fall. It will be appreciated that the arm 30 can only assume its lowermost position when the peg 63 can engage one of the notches 59, and the latter are arranged so that the arm 30 can only be lowered completely when the carriage is in such a position that the pipetting tubes 32 will engage one transversely extending column of the receptacles carried by the carriage 11. The cam surface 58 and pin 63 provide interlocking means designed to ensure that the carriage cannot be moved along until such time as the pipetting tubes 32 are in a sufficiently raised position to ensure the free passage of the receptacles beneath the lower end of same.

The apparatus may be used in a variety of different ways, but one particular way will now be described. Initially, the forty tubes 20 are filled with forty different samples of serum which it is desired to dispense, the

receptacles

23, 24, 27 and 29 being empty, and the receptacle 25 being filled with a diluent. The handle 41 is operated to ensure that the plungers 36 are fully depressed into the syringes 35, and the carriage 11 is aligned so that the rearrnost column of the tubes 20 is aligned beneath the pipetting tubes 32, which are then lowered so that they penetrate the samples of serum contained in these tubes. The handle 41 is operated to draw off a known volume of serum from each of the ten tubes 20 in the rearrnost column thereof into the ten pipetting tubes 32. The carriage 11 is then moved backwardly until the rearrnost column of the tubes 23 are aligned beneath the pipetting tubes, 32 which are then lowered so as to penetrate same. The handle 41 is then operated to discharge a known volume of the serum from each of the pipetting tubes 32 into their respective tubes 23. The carriage is again moved backwards, and the pipetting tubes lowered into the receptacle 25 when the handle 41 is operated to draw off a known volume of the diluent into each pipetting tube 32. The carriage is again moved backwardly until the pipetting tubes are aligned with the rearrnost column of holes 27 when the tubes 32 are again lowered to engage such holes. The handle 41 is operated to discharge all the fluid from the pipetting tubes 32 into the holes 27 to ensure mixing of the serum with the.

diluent. The handle 41 is then operated to draw ofl a known volume of the serum from each of the holes 27 into the tubes 32 leaving a predetermined volume therein. The carriage is again moved backward until the tubes 32 are aligned over the next column of holes 27, whereupon the tubes 32 are lowered, and the handle 41 operated to discharge a known volume of the serum into each of the holes 27. This last operation is repeated twice in the two following columns of holes 27, whereupon the carriage is moved forwardly to bring the receptacle 24 for waste beneath the pipetting tubes 32, which are lowered thereinto and the handle 41 operated to discharge any remaining serum and diluent from the pipetting tubes 32 into the receptacle 24. The entire cycle of operations thus far described is then repeated for each of the three remaining columns of tubes 20 containing samples of serum, in each case, the :carriage being moved to align the tubes 32 with the desired receptacles at each stage of the cycle.

The stops 43 on the guide 44 for the handle 41 may be arranged at predetermined positions to facilitate the operation of the handle 41 to draw up and discharge the desired and predetermined volumes of fluid at each stage of the operation cycle.

It will be appreciated that the apparatus can be used to dispense forty samples of serum each into a plurality of receptacles at known volumes and known dilutions in a very short time, both on account of the fact that ten samples may be dispensed simultaneously and also on account of the simple operations required to effect the dispensing.

A second example of multiple pipetting apparatus in accordance with the invention is shown in FIGURE4. The apparatus comprises a base on which a support 101 is slidably mounted by means of runners 102 fixed to the base. A tower 103 extends upwards behind the support 1431 alongside a casing 104 containing electrical control apparatus to be described later. The front of the casing 104 is fitted with a timer 105 and various control knobs 106 and indicating lights 109.

The tower is [provided with an upper rectangular slot 167 through which extends an angle member 108 detachably mounted on a bracket 99. The horizontal web of I rests on the top surface of the the angle member is formed with a slot 110 extending above the support 101 and in which are slidable mounts 111 each supporting a pipetting tube 112. Although only four pipetting tubes are shown more may be mounted in the slot 110 as required. Pipes 113 pass from the tops of the mounts 111 along the member 108 and through the slot 107 into the tower 103. A second slot 114 is spaced directly beneath the slot 107 and a vertically movable interlocking pin 115 serving for indexing the support 101 projects through the slot 114 so that its end overlies the top surface of a rail 116 fixed to the support and extending in the direction of its movement. Locating pieces 117 of which only five are shown, are movable to different positions along the top flanges of the rail 116. ,When the pin 115 is in the top of the slot 114 the locating pieces pass beneath the pin when the support 101 is moved along the base 100. When the pin 115 is in the lower position shown, it is spaced close to the top surface of the rail 116. Whether or not the pin 115 is allowed to assume the position shown, depends on the positions of the pieces 117. If the pieces 117 on the side nearest the pin are closely spaced so as to provide a continuous top surface the pin 115 will be prevented from assuming its lower position. However, if the pieces 117 are spaced sufficiently to provide a slot between them into which the pin 115 can fit then it will enter the slot and will assume the position shown. The length of the pin 115 is such that it can be stopped from entering a slot by the pieoes on both sides of the rail 116. Thus the clamping pieces 117 on one side of the rail can be used to form one side of each of a series of transverse slots and the precise positions of the other sides of the slots formed from further locating pieces mounted on the other side of the rail and overlapping those on the first side where a fraction of a width of a locating piece is required.

The support 101 comprises a carriage 118 of inverted channel shape with the runners 102 being fitted to the inside faces of the downturned flanges of the carriage. FIGURE 6B shows the carriage in more detail from which it will be seen to have a pair of end flanges 120 and a camming surface 121 formed on the outside of one downturned flange. In its top surface the carriage is pro vided with .two locating holes 122 for accommodating studs 123 projecting downwards from the underside of a tray 124 shown in more detail in FIGURE 6A which carriage 118 as shown in FIGURE 4. The tray 124 is provided with parallel upstanding side flanges 125 each of which serves as a guideway for opposite ends of a U-channel partition 126 which is movable to different positions along the tray 124. At its ends each of the partitions 126 is provided with a clamp 127 which may be tightened to lock the partition in a desired position. The partition is of channel shape and clamp blocks 128 are slidable to different positions along opposite sides of the channel. There is sufiicient spacing between the clamp blocks on opposite sides of the partition to enable them to be slid past one another without obstruction.

Referring again .110 FIGURE 4 the support 101 is provided with fixtures into which a programme card 130 can be fitted in order to suit a particular sequence of operation to be carried out. A pointer 131 on the base indicates the particular point in the programme at any instant and a hand lever 132 close to one end of the support 101 enables the support to be moved along the base 100 to difiiereut positions in accordance with the programme 130. The handle 132 is also rotatable to raise and lower the pipetting tubes 112 as will be described later.

The base 100 is provided with a handle 133 shown in more detail in FIGURES 7 and 9. The handle is movable to diiferent angular positions determined by adjustable stops 134 set to positions corresponding to volumes of liquids to be drawn into or expelled from the pipetting tubes 112. Each of the stops 134 is mounted on an armate frame 135 concentric with the axis of the handle 133, and one or both sides 136 of each stop 134 is planar to provide an abutment for the handle 133. An overrider button 137 is fixed in the top of the handle and is fixed to a peg 139 which cooperates with the abutment surfaces 136 when the button is not pressed. Where no planar abutment surface 136 is permitted the peg 139 is able to ride over the curved undersurface of the stop 134. However if the button 137 is pressed the peg 138 is also able to move past the abutment surfaces 136 so that the handle 133 is able to be moved to different positions past the stop. The button 137 acts against a spring 140 mounted inside the handle 133.

Turning to FIGURE 5, the top of the tower 103 provides a stand on which a reservoir bottle 141 may be placed. Piping 185 extends from the bottle through the tower to a wash trough 142 mounted in the base 100 directly beneath the number 108. When the wash trough is not in use the support 101 is able to pass freely over it.

The length of the wash trough is the same as the length of the slot 110 in the member 108 and is shown in more detail in FIGURE 8. It comprises a rectangular trough divided by a horizontal plate 143 into an upper compartment 144 and a lower compartment 145. A slot 146 slightly wider than the cross-sections of the lower endportions of the pipetting tubes 112, is formed in the plate 143 directly beneath the pipetting tubes and a removable sloping glass plate 147 slopes into the upper compartment 144 and terminates above the slot 146. An electrically operated immersion heater 148 provided with a thermal cut-out is mounted in lower compartment and a liquid inlet pipe 150 opens through the bottom of the compartment 145. A liquid outlet pipe 151 opens into the top compartment 144 through the plate 143 and extends downwards through the floor of the bottom cornpartment 145.

FIGURE 5 shows the method of raising and lowering the member 108 on which the pipetting tubes 112 are mounted. The bracket 99 supporting the member 108 is mounted inside the tower 103 on a telescopic guideway having a lower part 161 which is fixed inside the tower and an upper part 162 which is vertically slidable along the lower part. The bracket 99 is fixed to the upper part 162 and a cross brace 163 extends horizontally away from the member 108 and is provided at its endportion with a hole 164 which is a sliding fit along a slide rod 165 fixed at its upper and lower ends inside the tower. The cross brace 163 prevents undesirable horizontal movement of the member 108 about the guideway 160.

The weight of the member 168 is carried by a wire 166 which extends around a first pulley 167 in the upper end portion of the tower and around a deflector pulley 169 which is movable horizontally to vary the effective length of the wire 166. A tensator spring 79 in the top of the tower and attached .to the sliding part 162 counter-balances much of the weight of the pipetting tubes. The other end of the wire 166 is fixed to the periphery of a second pulley 168 mounted on a shaft 170 journalled into the tower between the

slots

107 and 114. A third pulley 171 is also fixed to the shaft 170 and a second wire 172 is fixed to the periphery of the third pulley 171. The second wire 172 extends around an idler pulley 173 which maintains it in tension and around a stationary mounted pulley 174 fixed in the base 100 at one end. The other end portion of the wire 172 extends through a tensioner 175, which is rotated by the hand lever 132 fixed to the carriage 118, to an anchorage 177 at the other end of the base 100. A helical spring 180 ensures the engagement of the tensioner with the wire 172.

A hanging link 181 is pivoted at its upper end to the third pulley 171 eccentrically with respect to its axis and carries the interlocking pin 115 at its lower end.

The first pulley 167 is fixed to one end of a lever 182 which is biased upwardly by a coil spring 183 against an adjustable stop. The lever is pivoted at 104 and is positionally controlled by a wire 186 which extends downwards through the tower- 103 and is anchored at its lower end to a cam rider 137 mounted at the free end of a spring loaded lever 188 as shown in FIGURE 8. The earn rider 187 is positioned in the path of movement of the cam surface 121 provided on the side of the carriage 118 as shown in FIGURE 6B. The camming surface 121 is so positioned that it engages the cam rider 107 to press it downwards when the support 101 is so far to the right of FIGURE 4 that is is not interposed between the pipetting tubes 112 and the wash trough 142.

The supply of liquid to the wash trough 142 is controlled by a solenoid operated valve 101 mounted in the top of the tower 103 beneath the reservoir bottle 141. Operation of the valve 191 is controlled by an electrical circuit shown in FIGURE 11 and described in detail later. The electrical circuit also controls operation of the immersion heater 148 in the wash trough 142, the in dieating lamps 107 in the casing and an air pump 149.

The pipes 113 from the mounts 111 extend through the slots 107 in the tower 103 and downwardly to a set of syringes 200 mounted in a line across the base 100 and shown in FIGURE 9. There is one syringe 200 provided for each of the pipetting tubes 112 and their plungers are held by fixtures 201 to a cross element 202 which is fixed at its ends to a pair of racks 203. The racks are engaged by pinions 204 fixed to an axle 205 extending through the side of the base and on which the handle 133, is mounted. The cylinders of the syringes 200 are provided close to their rear ends with branch pipes 207 opening into a manifold 208 which extends into a flask 210 containing a drying agent, such as silica gel, and a bacteriological filter. The flask 210 is mounted in the foot of the tower 103 and is accessible through a door (not shown) at the back of the tower. A pipe 211 extends through the back of the tower to the air pump 149 (see FIGURE 11) for driving air into the drying flask 210. The branch pipes 207 open into the cylinders of the syringes at positions which enable them to discharge dried air through the syringes 200 and the pipes 113 when the plungers are in their rearmost positions with respect to the syringes 200. At this position, which is indicated by one of the stops 134 associated with the handle 133, a microswitch 190 is operated.

FIGURE shows one of the mounts 111. This comprises -a bush 220 flanged at 222 and having its upper portion threaded and passing through the slot 110 where it is clamped into position by a lock nut 221 which clamps the member 108 to the flange 222. An elbow tube 223 is held in a socket at the upper end of the sleeve 220 by a cap nut 224 and a packing ring 225. The other end of the elbow passes into the end of the pipe 113 which is conveniently made of polyethene tubing. The pipetting tube 112 is made of polytetrafluoroethylene and its upper end is a force fit on a spigot formed in the underside of the mount 111. A stainless steel sleeve 226 closely surrounds the junction of the pipetting tube 112 with the mount 111 and prevents undue flexing of the pipetting tube at this point and assists their alignment.

FIGURE 6C shows the rail 116 in more detail and also illustrates the use of a T-piece 230 to bridge between 10- cating pieces 117 when a slot is not to be formed between the clamping pieces over a relatively large distance.

The T-piece 230 is gripped between the locating pieces 117a, 1171) and 1170, to prevent lowering the pin 115, and slots for reception of the pin are formed between the pairs of clamping pieces 1172, 117 at each end of the T-piece. The locating pieces 117 are provided in different sizes to suit different lengths of receptacles 230 into which pipettin g is to be carried out.

Referring again to FIGURE 4 the receptacles 230 into which liquid is to be pipetted are mounted in a test tube rack 231 of standard size. Although only one such rack is shown in FIGURE 4 it is to be understood that several such racks, arranged side by side, would normally be used and they are standard items of laboratory equipment. The racks 231 may come in several difierent sizes according to the purpose for which they are intended and the number of receptacles which are to be carried. For clarity a rack having two columns of eight openings and containing four test tubes 230 has been shown, the rack extending entirely across the Width of the tray 124. However dilferent sizes of rack may be of different lengths but can nevertheless be firmly clamped in position on the tray by the partitions 126 as is described below.

FIGURE 11 shows the electrical wash control circuit for the apparatus. It comprises a main ON/OFF switch 29 which closes to complete electrical circuits to a number of cam operated contacts CCI, CC2, CC3, CC4 and C05. The cams controlling the contacts are driven in unison by the timer and are so arranged that the washing sequence is completed in one complete revolution of the timer 105. During one complete revolution of 360 the contacts CO1 and CC2 are closed between 1' and 201; the contact CC3 is closed between 340 and 20; the contact CO4 is close-d between 0 and 200; and, the contact CCS is closed at 360.

The contact CC2 is a change-over contact and selectively controls operation of the pump 149 and the heater 148. During the arc l-201 the heater 148 is energised and during the arc 201-1 the pump 149 is energised. The electrical supply to the timer 105 and the contact CC2 is controlled by a manually operable switch 189 which, when opened, allows the pipetting tubes to be washed out with cold water, but which is closed it the washing sequence employing the timer 105 is to be used. Various lamps 109a-d are used to signify different stages in the washing sequence. The contact CC4 is also a change-over contact and is in the position shown during the 0-200.

A change-over contact 179' controls the supply to the manual switch 189, the contact 179' being operated by a microswitch 179 in the tower 103 as shown in FIGURE 5. The microswitch 179 is so arranged that the contact 179' is in the position shown in FIGURE 11 if the pipetting tubes 112 are lowered sufficiently for their tips to reach the surface of the liquidin the wash trough 142. If the pipetting tubes are above this point the contact 179' assumes its lower position. Operation of the microswitch 179 is carried out by its engagement with the movable part 162 of the slideway 160 during lowering of the pipetting tubes 112.

To prepare the apparatus for use the operator places the test tube racks 231 which are required onto the tray 124.

Each of the test tube racks is held in place by two partitions 126 which are moved against opposite sides of the rack. The partitions 126 are only able to move parallel to themselves so that they ensure, by engaging the sides of the racks 231, that the columns of receptacles 230 extend parallel to the line of pipetting tubes 112. The spacing between the pipetting tubes 112 is arranged to be the same as that between the receptacles of each column and the test tube racks 231 are clamped in the position at which the pipetting tubes engage with the receptacles, by adjustment of the clamping blocks 128, which are then tightened. The locating pieces 117 are then positioned to ensure that the interlocking pin 115 can pass between two adjacent pieces 117 when the pipetting tubes 112 rest centrally in each row of receptacles. The columns of receptacles are next brought into exact agreement with the programme card and to do this the pipetting tubes 112 are raised and each column is brought beneath the row of pipetting tubes 112 which are then lowered by means of the hand-lever 132 into respective receptacles 230 of a column. The programme card 130 is then marked 3 at the point indicated by the pointer 131. When this has been done two of the locating pieces 117 on opposite sides of the rail 116 are then locked in position.

When all of the test tube racks or similar such devices which may be used for different for-ms of receptacles are clamped into their correct positions and the programme card 130 completed the bottle 141 is placed on top of the tower 103 and connected to the piping 18S extending to the wash trough 142. Also, the stops 134 are placed at different positions along the path of movement of the handle 133 according to volumes of liquids it is required to draw into and expel from the pipetting tubes 112. The positions of the stops 134 are signified by a calibrated scale (not shown) extending around the path of movement of the handle 133. The apparatus is now ready for use.

To use the apparatus the hand lever 132 is rotated counter-clockwise to raise the line of pipetting tubes so that their lower ends are lifted clear of the tops of the receptacles 230. The action of rotating the hand lever 132 tensions the wire 172 and causes the pulley 171 to rotate in a clockwise direction as will be clear from FIG- URE 5. This rotation is transmitted through the shaft 170 to the second pulley 168 so that the wire 166 is drawn around the top pulley 167 and pulls the member 108 upwards. This upward movement is permitted by the telescopic guideway 160 and any tendency for the line of pipetting tubes to twist is resisted by the engagement of the cross-brace 163 with the slide rod 165. During rotation of the said pulley 171 the hanging link 181 is also drawn upwardly so that the interlocking pin 115 is lifted clear of the clamping pieces 117 or T-pieces arranged along the rail 116. The height of the locating pieces 117 selected is such that the interlocking pin 115 does not clear the slot formed between them until the lower ends of the pipetting tubes 112 are clear of the tops of the receptacles 230.

The support 101 is now displaced by the hand lever 132 along the base 100 to the first position indicated by the pointer 131 on the programme card 130. At this pOSitiO)? the handle 132 is allowed to rotate in a clockwise direction. If the pipetting tubes 112 are not correctly aligned with a column of receptacles the interlocking pin 115 will not enter the corresponding slot formed between the clamping pieces 117 but will engage the top surface of one or either of the clamping pieces. This prevents further rotation of the third pulley 171 so that further lowering of the member 108 is prevented before the pipetting tubes 112 reach the level of the tops of the receptacles 230.

Assuming the apparatus has been set up correctly the interlocking pin 115 passes between the clamping pieces 117 defining the slot associated with the first position and allows the lower ends of the pipetting tubes to be lowered into the column of receptacles. When the pipetting tubes are in their lower positions. their weight is carried by the

wires

166 and 172 and the interlock pin 115 is just clear of the top surface of the rail 116.

The operator draws the desired volumes of liquids into the pipetting tubes 112 'by rotation of the syringe-operating handle 133 up to a stop 134 as shown in FIGURE 9. The hand lever 132 is then rotated in the reverse direction to raise the pipetting tubes and after they are lifted clear of the receptacles 230 the interlocking pin 115 allows the support to be moved to the next position indicated by the programme card 130. It will be appreciated that the engagement of the interlocking pin 115 in the slot formed between the clamping pieces 117 ensures that the support 101 cannot be moved as long as the pipetting tubes are engaged in the receptacles 230.

At the next position the procedure is repeated and perhaps a second liquid is drawn into the pipetting tubes.

At a third position denoted by the programme card it may be required to mix the two liquids contained in the pipetting tubes, in a column of receptacles. To accomplish this the pipetting tubes 112 are lowered into respective recepetacles 230 of the column, as described above, and the handle 133 is moved in the reverse direction. This expels the liquid from the pipetting tube into the column of receptacles. To mix the liquid in the receptacles thoroughly the handle 133 may be worked backwards and forwards a few times. Samples of the mixed liquid may then be transferred by the pipetting tubes 112 to other columns of receptacles as required.

Between different programmes, or at periods during a single programme it may be required to clean the pipetting tubes thoroughly. This may be carried out either by a cold wash, in which case the manual switch 189' is opened, or by a hot wash, in which case the manual switch 189 is closed.

The procedure for cold washing will first be described.

The manual switch 189' is opened and the support 101 is moved as far as the right of FIGURE 4 as possible so that the camrning surface 121 of FIGURE 5 forces the cam rider 187 downwards. This draws wire 186 downwards also so that the pulley 167 in the top of the tower 103 is pulled downwards against the spring 183. This lowers the line of pipetting tubes 112 from their upper positions by twice the downward movement of the pulley 167.

The hand lever 132 is then rotated to lower the line of pipetting tubes 112 and, as a result of the upper pulley 167 being lowered, the lower ends of the pipetting tubes are able to descend below the level of the support 101 and into the slot 146 of the wash trough 142.

When the tips of the pipetting tubes reach the top of the wash trough 142 the descending upper part 162 of the slideway 160 operates the microswitch 179 so that its changeover contact 179' moves to the position shown in FIGURE 11. At this time the contact CC4 is in the position shown so that the solenoid-operated valve 191 is energised by way of the closed contact CO3 and opens to allow wash liquid to flow from the reservoir 141 into the bottom compartment 145' of the wash trough 142. The liquid from the lower compartment 145 flows upwards past the lower end portions of the pipetting tubes 112 with a millrace effect so that the end portions are thoroughly cleaned by the continuously flowing hot liquid. At the end of the washing time the operator turns the hand lever 132 to lift the pipetting tubes 112 a small amount so that their tips are drawn out of the slot 146. and rest against the top surface of the sloping glass plate 147. Glass is hydrophilic whereas the polytetrafluoroethylene of the pipetting tubes is hydrophobic so that any drops of water on the tips of the pipetting tubes are transferred to the glass plate 147. This reduces the risk of dilution of the next liquid into which the pipetting tubes are dipped by water adhering to the outside of the pipetting tubes from the wash trough 142.

The hand lever 132 is fully rotated counterclockwise to raise the pipetting tubes 112 to their original positions.

As a result the microswitch 179 returns to its original state and its contact 179' breaks the electrical circuit to the valve 191. Valve 191 is de-energised and closes to stop the flow of wash liquid into the wash trough 142'. Throughout the washing the timer remains unenergised and the contact CCS is closed to light the lamp 109d.

In certain circumstances it is necessary to thoroughly clean and dry the end-portions of the pipetting tubes 112 and for this purpose the hot wash, which is time sequenced by the timer 105, is necessary.

To use the hot wash the switch 189' is closed and the lower end-portions of the pipetting tubes 112 are lowered into the wash trough 142 in exactly the same way as described above. However in this case operation of the microswitch 179 energises the timer 105 as well as the solenoid. The cams driven by the timer 105 are rotated and almost immediately the contacts CC1, CCZ, and CO are operated as they all respond to 1 of rotation. The contact CCZ changes over to energise the immersion heater 148 and the contact CC1 lights the lamps 1ti9'a to signify operation of the heater. Should the reservoir bottle 141 inadvertently be empty, over-heating of the immersion heater is prevented by a thermal cut out 148 so that excessive heating of the lower end-portions of the pipetting tubes is prevented.

The contact CC3 remains closed until the cams have rotated through 20 during which time the end-portions of the pipetting tubes are washed in cold water. After 20 of cam rotation contact 0C3 de-energises the valve 191 which interrupts the supply of wash liquid from the bottle 141. As a result the liquid in the trough 142 is raised to its boiling temperature. The wattage of the immersion heater 148 and time taken for the cams to rotate through 180 are so selected that the wash liquid, which may be water, is just brought to its boiling point and held there while the pi-petting tubes may be worked up and down by the handle 132 to rinse thoroughly. The temperature of the wash liquid is sufiiciently high to kill vegetative micro-organisms which might be present and the time taken for the cams to rotate to 200 is sufficient for this purpose.

At 200 the contact CC4 changes over to break the electrical supply to the timer 105 and energises a lamp 1090. This indicates that the rinsing sequence is completed.

When the operator observes light 1090 he lifts the pipetting tubes by the hand-lever 132 to their upper position after allowing their tips to rest momentarily on the glass plate 147, and this causes microswitch 179 to operate and contact 179 to change-over.

If at this stage the plungers of the syringes 2% are not wound back to their furthest extents the microswitch 199 will not be operated and the electrical circuit to the timer 105 will be broken. To complete this circuit the operator winds back the plungers until he reaches a stop 134. He will then see the lamp 111% light to indicate that the timer is again operating and therefore the microswitch 199 has been closed. Simultaneously with the timer 105 operating the valve 191 is opened to allow cold water from the bottle 141 to flush out the hot rinse liquid from the trough 142.

A second or so later after operation of the timer the cams are rotated to 201 and the contacts CCZ and CC1 operate to transfer the electrical supply from the immersion heater to the pump 149 and to signify that this has taken place.

The pump 149 drives dry air from the flask 21% through the syringes 201), this being permitted by the withdrawn plungers, and through the piping 113 no the pipetting tubes 112 The dry air absorbs any moisture remaining inside the tubes 112 and this is facilitated by the tubes 112 still being Warm from the previous rinsing operation. The pump continues to run until the cams have rotated through the remainder of the 360 when cam contact CC4 again changes over to break the electrical circuit to the timer 105. At 360 cam CCS also closes to indicate the cams have completed the entire sequence and the circuit is ready to start a fresh sequence when desired.

During operation of the pump 149 the cam pass the 340 position at which the contact CC3 is once again closed to open the valve 191 and allow cold liquid from the bottle 141 to flush the hot contaminated rinse liquid from the trough 142. At the end of the washing and drying sequence the support 101 is returned to its original position shown in FIGURE 4 so that the cam surface 121 no longer bears against the cam rider 187. The spring 183 returns the pulley 157 to its topmost position to lift the pi petting tubes 112 to their upper positions in readiness for the next sampling operation.

Although the operation of the immersion heater 148, pump 14%, and timer has been described in a sequence controlled circuit it will be understood that each may be provided with its own over-riding switch to enable it to be switched on and off independently if desired.

It will be appreciated that it is not intended to limit the scope of the invention to the above examples only, many variations, such as might readily occur to one skilled in the art, being possible, without departing from the principles of the invention.

Thus, for example, the mechanical construction of the apparatus may be varied in any number of ways without departing from the principles of operation. For example, in place of the solenoid valve shown in FIG- URE 8 the control of wash liquid from the flask 141 maybe carried out by mechanically pinching the piping extending from the flask 141 to the wash trough. Such pinching may be carried out by sandwiching the piping between a portion of the lever 182 so that the pinch is relieved when the pulley 167 is drawn downwardly by the wire 1%.

The pipetting arrangements may be different and the pipetting tubes need not be formed from polytetrafluoroethylene though this material is preferred, since as there is no tendency for liquids to wet the surfaces of such tubes very accurate quantities of fluid can be dispensed.

The apparatus may be used in any desired manner to effect any known method of dispensing serological or other fluid samples for analysis. Thus the carriage may support receptacles for reagents of various kinds for mixing with the samples under test, or receptacles for rinsing media for the pipetting tubes between any desired stages or cycles of operation.

The apparatus of the invention is able to dispense liquids with accuracy and at great speed.

As an example of the speed of use of the first apparatus described above, it was used by a skilled operator to prepare serial dilutions of 1 in 8, 1 in 16, 1 in 32 etc. The sequences necessary took approximately 2 /2 minutes, 1% minutes and 1% minutes respectively whereas to do the job manually a skilled operator took 20 minutes, 10 minutes and 10 minutes respectively. The accuracy of measurement was superior to that attainable by manual methods and in general, in serological work, the speed of use is between 5 and 10 times faster than with conventional methods. In another example using routine procedures which required eight measurements for each specimen, a single technician has, by using the apparatus of FIGURES 1 to 3, been able without difficulty or fatigue to dispense 500 specimens in an hour. Were conventional manual methods to be used it would require two technicians each working three hours to dispense 500 specimens.

I claim:

1. Multiple pipetting apparatus comprising a base, a support on the base for holding receptacles disposed in rows and columns extending along and across the support respectively, a member extending across the support above the level of the receptacles, a mechanism for producing relative longitudinal movement between the support and the member, a line of pipetting tubes mounted on the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, an element for operating the syringes in synchronism, a device for simultaneously raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles, said support including a rectangular tray having slidable partitions movable parallel to one pair of sides of the tray and carrying adjustable clamping blocks movable parallel to the other pair of sides of the tray.

2. Apparatus as claimed in claim 1, in which the support is movable with respect to the base.

3. Multiple pipetting apparatus comprising a base, a support mounted on said base for holding receptacles disposed in rows and columns extending along and across the support respectively, a tower extending upwards from the base at one side of thesupport, an upright telescopic guide mounted inside the tower, a member extending horizontally away from the guide to an opening in the tower and extending across the support above the level of the receptacles, a mechanism for moving the support along the base, a line of pipetting tubes mount: ed on the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, an element for operating the syringes in synchronism, a device for simultaneously raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles, and interlock means for preventing operation of the device until alignment of said lower ends.

4. Apparatus as claimed in claim 3, including inside the tower a slide rod extending parallel to the base, and a brace extending transversely in a horizontal direction away from the member and slidable along the slide rod at its free end.

5. Multiple pipetting apparatus comprising a base, a support on said base for holding receptacles disposed in rows and columns extending along and across the support respectively, a member extending across the support above the level of the receptacles, a mechanism for producing relative longitudinal movement between the support and the member, a line of pipetting tubes mounted in the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, an element for operating the syringes in synchronism, a device for raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles, means defining slots spaced along the support, an interlock pin vertically movable between two positions at one of which it engages in a selected slot to prevent relative movement between the support and the pipetting tubes and at the other of which it is spaced from the slot to allow such relative movement, and a linkage operatively connected between the pin and the member so that they are moved in synchronism.

6. Apparatus as claimed in claim 5, in which the linkage includes a bell crank lever.

7. Apparatus as claimed in claim 5, including a pulley in said linkage and rotated by said device, and a swinging link depending from said pulley and having the interlock pin projecting from its lower end through a vertical slot confining movement of the pin to a vertical direction.

8. Apparatus as claimed in claim 5, in which said means defining slots comprise adjustable clamp blocks slidable to different positions along a track extending along one side of the support.

9. Multiple pipetting apparatus comprising a base, a support on said base for holding receptacles disposed in rows and columns extending along and across the support respectively, a member extending across the support above the level of the receptacles, a mechanism for producing relative longitudinal movement between the support and the member, a line of pipetting tubes mounted on the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, a rack and pinion unit, a handle for rotating the pinion, an element movable with the rack towards and away from the syringes, fixtures connecting the plungers of the syringes to the element for operating the syringes in synchronism, a device for raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles, adjustable stops for co-operating with the handle to limit its movement, and an over-rider button on the handle for permitting it to ride over the stops when desired.

10. Multiple pipetting apparatus comprising a base, a support on the base for holding receptacles disposed in rows and columns extending along and across the support respectively, the member extending across the support above the level of the receptacles, a mechanism for producing relative longitudinal movement between the support and the member, a line of pipetting tubes mounted on the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, branch pipes extending from the rear end portions of respective syringes to a common pipe connection for supplying dried air severally to the syringes so that the dried air passes through the pipes and the pipetting tubes, an element for operating the syringes in synohronism, and a device for raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles.

11. Apparatus as claimed in claim 10, further comprising a handle common to said mechanism and to said device, said handle being movably mounted on said support and operable for producing said relative longitudinal movement and for raising and lowering said pipetting tubes.

12. Multiple pipetting apparatus comprising a base, a support on the base for holding receptacles disposed in rows and columns extending along and across the sup port respectively, a member extending across the support above the level of the receptacles, a mechanism for producing relative longitudinal movement between the support and the member, a line of pipetting tubes mounted on the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, an element for operating the syringes in synchronism, a device for raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles, a wash chamber extending parallel to the columns, means for lowering the lower end portions of the pipetting tubes into the wash chamber to clean them, means for circulating wash fluid past the end portions of the pipetting tubes when dipping into the wash chamber, means in said wash chamber defining upper and lower compartments and an elongated opening extending between said compartments and through which said end portions of the pipetting tubes extend, an inlet for wash liquid in said lower compartment, an outlet for wash liquid in said upper compartment, an immersion heater in said lower compartment and terminating above one edge of said elongated opening.

13. Apparatus as claimed in claim 12, said wash liquid circulating means including a reservoir mounted above the pipetting tubes, a pipe connecting the reservoir to the liquid inlet of the lower compartment, a valve disposed in said pipe for controlling flow of wash liquid therethrough, and means for operating said valve in unison with lowering movement of the end portions of the pipetting tubes into the wash chamber.

14. Multiple pipetting apparatus comprising a base, a support movable on said base and for holding receptacles disposed in rows and columns extending along and across the support respectively, a member extending across the support above the level of the receptacles, a mechanism for producing movement of the support along the base, a line of pipetting tubes mounted on the member above the level of respective rows of receptacles, a set of syringes, pipes individually connecting the syringes to the pipetting tubes, an element for operating the syringes in synchronism, a device for raising and lowering the pipetting tubes when their lower ends are aligned with a column of receptacles, interlock means for preventing operation of the device until alignment of said lower ends, a wash chamber mounted on the base be- 15 16 neath the level of the support and extending parallel to References Cited the columns, means for lowering the lower end portions UNITED STATES PATENTS of the pipetting tubes into the wash chamber, means for circulating wash fluid past the end portions of the 3 223 Hammond 2:3 pipetting tubes when in the wash chamber, cam means 5 g 8/1964 3: 22: -n-- ;-S-I:I- -S--- 7 23 operated by said support when not lnterposed between 3:188:181 6/1965 Peterson et a1. 73 425'4 the wash chamber and the pipetting tubes, and a safety element connecting the cam means to the member and r preventing said lowering means becoming operative until LOUIS PRINCE Primal) Examme" operation of the cam means. 10 S. C. SWISHER, Assistant Examiner.