Background of the Invention Micro titre plates are used widely across the world in numerous different laboratory testing and sampling procedures. Because of the number of samples to be tested and processed in these procedures an automated system is typically used. In such an automated system it is particularly desirable to access the required micro titre plate and subsequently withdraw or place the very small or micro litre samples within the micro titre plate as quickly as possible.

One of the difficulties associated with the above described process is that the micro titre plates are typically stacked one atop the other. This means that in order to access a particular micro titre plate within a stack it is necessary to first remove all of the micro titre plates from above it. After the micro titre plate is used it must then be replaced on the stack and the previously removed micro titre plates restacked.

An automated system has previously been developed to stack and unstack micro titre plates and to subsequently transport the required micro titre plate to the liquid aspiration and dispensing station. Such a system typically grasps the micro titre plate by means of a pair of opposed fingers which apply inward pressure to the external side walls of the micro titre plate. In this manner, the micro titre plate can be grasped and subsequently held during transport to liquid aspiration and dispensing station and back to the stack of micro titre plates.

However, this system suffers from the disadvantage that it is not always possible to firmly grip the micro titre plate and in some instances the micro titre plate can be dislodged and the sample lost. Furthermore, because of the manner in which the micro titre plate is grasped by the opposed fingers and the difficulty in maintaining the micro titre plate in the desired horizontal orientation, the speed of movement towards the liquid aspiration and dispensing station must be relatively slow. Thus, the time taken to select a particular micro titre plate, transport it to the liquid aspiration and dispensing station, perform the required procedure and return it to the stack is also slow.

The present invention seeks to address at least some of the above mentioned problems.

Summary of the Invention According to a first aspect of the present invention there is provided a micro titre plate transporter module including a carriage for receiving a micro titre plate, an engaging unit arranged to engage against a downwardly depending wall portion of a micro titre plate and to grasp said wall portion so that said micro titre plate can be transferred onto said carriage to a position wherein the micro titre plate is supported by said carriage.

Preferably, said carriage includes a substantially horizontally orientated loading platform for receiving said micro titre plate and a pair of opposed side walls arranged to prevent inadvertent side to side movement of said micro titre plate.

The loading platform has a first longitudinal axis, which is known as its receiving axis, which extends substantially parallel to the longitudinal axis of the pair of opposed side walls.

The carriage may also include a pair of elongate top stop members. Each top stop member being arranged for attachment to its respective side wall so as to prevent inadvertent movement of the micro titre plate in a substantially vertical

orientation. Each top stop member is preferably connected to its respective side wall by a spring biased connecter so that limited substantially vertical movement of the top stop member can occur. This limited movement of the top stop member allows limited adjustment of the positioning of the micro titre plate on the loading platform in the event that the micro titre plate jams or catches during transfer of the micro titre plate onto the loading platform.

The engaging unit preferably includes an engaging member, a holding and positioning means and a carriage member. The engaging member and the holding and positioning means are mounted on the carriage member. The engaging member is arranged to engage an inner side of said downwardly depending wall portion of said micro titre plate so as to enable transfer of the micro titre plate onto the loading platform.

The engaging unit is preferably arranged for substantially horizontal linear movement in a direction substantially parallel to the receiving axis or z-axis of the loading platform. This horizontal linear movement along the z-axis enables the engaging unit to be driven between a first forward position in which the engaging member engages the inner side of said downwardly depending wall portion of said micro titre plate, and a second rearward position in which the micro titre plate is fully received on the loading platform.

The engaging member preferably extends substantially vertically upward from the carriage member so that it is arranged in use to be substantially parallel to the downwardly depending side wall portion of the micro titre plate to be located on the loading platform.

The carriage member is preferably positioned in a cut-out or slot in the loading platform and is arranged to be driven along the cut-out or slot so as to move between the first and second positions. The engaging unit is located vertically relative to the loading platform so that during movement between the first and second positions a lowermost edge of the micro titre plate being transferred

onto the carriage is arranged for sliding contact with the upper surface of the loading platform.

The carriage member preferably includes a bearing arrangement which is arranged to enable the engaging unit to move smoothly along the length of the side walls of the cut-out or slot in the loading platform. Movement of the engaging unit is caused by a driving wire which passes around a pulley system mounted on the underside of the loading platform and through a pair of apertures located in a depending portion of the carriage member. A stepping motor drives the driving wire as signalled to do so by a first micro processor mounted on the micro titre plate transporter module.

The holding and positioning means preferably includes an inverted substantially L-shaped member which is connected to a solenoid. The solenoid is mounted on the carriage member behind the holding and positioning means. The solenoid is preferably controlled by the first microprocessor and is arranged to move the holding and positioning means forward and back in a direction along the z-axis. The L-shaped member preferably includes a first and second surfaces. The first surface is arranged to abut against the outer side of said downwardly depending side wall portion of said micro titre plate when the solenoid is in an"off"condition. The second surface is arranged to abut against the outer side of said downwardly depending side wall portion of said micro titre plate when the solenoid is in an"on"condition and when the transporter module is replacing a micro titre plate into a hotel module.

When the solenoid is in the"off"condition, the L-shaped member is moved in a horizontal plane towards said engaging member so that in use the downwardly depending wall portion of the micro titre plate can be located or locked there between.

The-spacing between the first surface of the L-shaped member and the engaging member is at its greatest size when the solenoid is in its"on"

condition. This enables the downwardly depending wall portion of a micro titre plate to be readily located therein.

The holding and positioning means is configured so that it can accommodate different types of micro titre plates and can securely hold the different types of micro titre plates during transfer of the micro titre plates onto the carriage and during subsequent movement of the plate transporter module.

A first signal means is provided on the carriage to signal when a micro titre plate is properly located in the second position on the loading platform. The signal means may include a limit switch. A second signal means is provided on the loading platform to determine the home or zero position for the solenoid.

The plate transporter module is preferably arranged for linear movement in a vertical and a horizontal direction (i. e. along an x and y-axis). The plate transporter module is preferably mounted for vertical or y-axis movement along a transporter column. The transporter column in turn is mounted for linear horizontal or x-axis movement in a table track. Horizontal and vertical movements of the plate transporter module are driven by timing belts connected to respective stepping motors.

The first micro processor mounted on the plate transporter module is used to control the engaging unit and the solenoid. The first micro processor also receives the signal from the signal means so that it can identify when a micro titre plate is properly located in the second position on the loading platform.

The micro processor may include a timer which times the movement of the engaging unit between the first forward and the second rearward position. If the engaging unit does not reach the second rearward position within a set time limit the micro processor may be programmed to prevent any further movement of the engaging unit.

According to a second aspect of the present invention there is provided a hotel for housing micro titre plates. The hotel preferably includes a plurality of bays, each bay being arranged to house a single micro titre plate. Each bay is preferably arranged so that a respective micro titre plate can be removed from its bay by substantially horizontal movement as a result of engagement of a rear side of a depending wall portion of the micro titre plate with a removal means.

In one preferred embodiment, the removal means includes the engaging member of a plate transporter module in accordance with a first aspect of the invention.

In one preferred embodiment, each bay includes opposed side wall members, a floor member and a rear wall member. The floor member may include a plate which extends across the width of the bay and is connected to each of the opposed side wall members. Alternatively, the floor member may include a ledge extending from each of the opposed side wall members. The ledges being of sufficient width and length so as to support the micro titre plate resting thereon.

In a particularly preferred form of the invention, an hotel would include four columns of bays. Each column of bays would include thirty-two bays into which individual micro titre plates could be inserted. Accordingly, each hotel would contain one hundred and twenty-eight bays and therefore one hundred and twenty-eight micro titre plates could be located within the hotel.

It is envisaged that two or more hotels may be located side by side to form an hotel module.

In accordance with a third aspect of the present invention there is provided a replicator system including at least one micro titre plate transporter module, at least one hotel module, and at least one delivery station module to which micro titre-plates can be delivered.

Preferably, the replicator system would also include an aspiration delivery head module. Typically, the aspiration delivery head module would contain ninety-six syringes operating in unison so as to enable aspiration from or dispension into each of the sample holders of a micro titre plate. The replicator system in this configuration is more commonly called a liquid aspiration and dispensing system.

Preferably, the replicator system would also include at least one wash station to wash the syringes in the aspiration delivery head after use.

The liquid aspiration and dispensing system is preferably enclosed by panels, for example perspex panels. The system is preferably enclosed so as to prevent ingress of dust and other contaminants into the station and to prevent access to the station during operation.

Description of the Drawings Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of a liquid aspiration and dispensing station in accordance with an embodiment of the invention.

Figure 2 is a front view of an hotel of an hotel module in accordance with an embodiment of the invention.

Figure 2a illustrates an alternative construction of the bays of an hotel in accordance with an embodiment of the invention.

Figure 3 is a perspective view of a micro titre plate transporter module according to an embodiment of the invention. (The components for attaching the transporter module to the column are not shown).

Figure 4 is an underneath view of the transporter module shown in Figure 3.

Figure 5 is an end view of the transporter module.

Figure 6 is a schematic part side view showing a portion of a micro titre plate being engaged by an engaging member of a plate transporter module in accordance with an embodiment of the invention. The solenoid 75 is in the"off" condition and the micro titre plate is held tightly.

Figure 7 is similar to Figure 6 but shows the solenoid 75 in the"on"condition.

Figure 8 is a top view of the transporter module with a micro titre plate partially loaded onto the loading platform of the transporter module.

Detailed Description of the Preferred Embodiments Figure 1 illustrates schematically a liquid aspiration and dispensing station 10 which includes an hotel module 12, a micro titre plate transporter module 14, a delivery station module 16 and an aspiration delivery head 18. The delivery station module 16 is located on a liquid delivery table 17 and includes five bays 16a for receiving micro titre plates 100 ready for an aspiration/dispense operation. A primary sample table 19 including a plurality of bays 19a is located on the liquid delivery table 17 directly behind the delivery station module 16. Deep well plates, mother micro titre plates, non auto-refilling reservoir stations or wash stations may be located in the bays 19a.

The aspiration delivery head 18 is mounted on an arm 18a which can be driven by a motor along a y'-axis (shown in Figure 1). The delivery head 18 is arranged to be driven along the arm 18a by a motor so that the delivery head 18 can be driven along a x'-axis. Accordingly, the delivery head 18 can be manoeuvred to any required position above the liquid delivery table 17.

The aspiration delivery head 18 includes ninety-six syringes operating in unison which are arranged to aspirate from or dispense to any micro titre plate 100 or mother micro titre plate located on the liquid delivery table 17.

Wash stations (not shown) are typically provided to wash the syringes in the aspiration delivery head 18. Each wash station preferably has a separate liquid supply allowing the use of different solvents or different purities of water.

The liquid aspiration and dispensing station 10 is arranged to be positioned on a table or other structure and is enclosed by a frame 20 which would typically be covered by a number of panels. The panels may be made of a material such as Perspex and are arranged to prevent ingress of dust or other contaminants into the aspiration station 10 and to prevent access to the station 10 during its operation.

Figure 2 illustrates an hotel module 12 including a pair of hotels 12a, 12b, mounted side by side. Each hotel 12a, 12b, includes a pair of opposed side walls 22a, 22b, a top wall 24 and a rear wall (not shown). Each hotel module 12a, 12b is divided into a number of bays 26 by a series of ledges 33. A ledge 33 extends from each of the opposed side wall members 22a, 22b. The ledges 33 being of sufficient width and length so as to support a micro titre plate 100 resting thereon.

In an alternative arrangement shown in Figure 2A each bay 26 of the hotel 12a, 12b is defined by a pair of opposed side wall members and a floor member 32.

The floor member 32 may extend across the width of the bay 26 and be connected to each of the opposed side wall members 30a, 30b. In such an arrangement, the front edge of the floor member 32 would include a cut-out portion. This cut-out portion enables the micro titre plate 100 to be removed from the bay 26 in a manner to be loading platform subsequently !

Each bay 26 is arranged to receive and support a single micro titre plate 100 in a substantially horizontal orientation. As shown in Figure 2, each hotel 12a, 12b includes four columns of bays 26, with each column including thirty-two rows.

Accordingly, each hotel 12a, 12b includes one hundred and twenty-eight bays 26 and therefore can accommodate one hundred and twenty-eight micro titre plates 100.

As shown in Figure 1 and as will be explained in more detail below, the hotel module 12 is mounted in such a manner that the plate transporter module 14 can be used to access any one of the bays 26 of the hotel module 12a, 12b.

Micro titre plate transporter module 14 is mounted on a column 50 in such a manner that it can be driven up and down along the length of the column 50 by a timing belt connected to a first stepping motor 51 a. This movement will hereinafter be referred to as movement along the y-axis. The free ends 52 of the column 50 are mounted in respective upper and lower tracks 56 so that the column 50 can be driven along the tracks 56 by a timing belt connected to a second stepping motor 51 b. This movement will hereinafter be referred to as movement along the x-axis. Thus, the transporter module 14 can be transported from a position in front of the hotel module 12, to a position in front of the delivery station module 16 and back to the hotel module 12. The transporter module 14 can be raised and lowered along the length of the column 50 so that it can be positioned in front of any one of the bays 26 of the hotel module 12.

The micro titre plate transporter module 14 as shown in Figures 3 to 6 includes a loading platform 62 for receiving the micro titre plate 100. The loading platform 62 may be formed from two planar members which are spaced apart so that an engaging unit 70 can be located in an elongate aperture 63 formed therebetween. Alternatively, the loading platform 62 may be formed from a single planar member with an elongate slot formed therein. The engaging unit 70 will be described in more detail below.

A pair of opposed vertical side walls 64 are connected to the loading platform 62 and are arranged to prevent inadvertent side to side movement of a micro titre plate 100 located on the loading platform 62. A top stop member 66 is mounted to each of the side walls 64 by a spring biased connector 68 so that limited substantially vertical movement of the top stop member 66 can occur.

This limited movement of each top stop member 66 allows limited adjustment of the positioning of a micro titre plate 100 on the loading platform 62 in the event that the micro titre plate 100 jams or catches during transfer of the micro titre plate 100 onto the loading platform 62. The top stop member 66 also prevents the micro titre plate 100 from jumping vertically during movement of the transporter module 14 from a position in front of the hotel module 12 to the delivery station module 16 and vice versa.

The loading platform 62 has a first longitudinal axis, which is known as the 3- axis, which extends substantially parallel to the longitudinal axis of the pair of opposed side walls 64.

The engaging unit 70 is best illustrated in Figures 4 to 6. The engaging unit 70 includes a carriage member 71, an engaging member 72 and a holding and positioning means 74. The engaging member 72 and the holding and positioning means 74 are mounted on the upper face of the carriage member 71. The engaging member 72 has an engaging portion 72a which extends upwardly from the carriage member 71 and is arranged in use to engage an inner side of a downwardly depending wall portion 100a of a micro titre plate 100.

As best illustrated in Figure 6, the holding and positioning means 74 includes an inverted L-shaped member which is connected at a rear side to a solenoid 75.

The solenoid 75 is controlled by a first microprocessor 80 mounted on the top of the transporter module 14. The solenoid 75 is arranged to move the holding and positioning means 74 towards and away from the engaging portion 72a of the

engaging member 72. In other words the solenoid 75 moves the holding and positioning means in the direction of the z-axis.

The L-shaped member has a first surface 74a arranged to abut against an outer side of the downwardly depending sidewall portion of the micro titre plate 100 when the solenoid 75 is in the"off"condition. This would for example occur when a micro titre plate 100 is being transferred from the hotel module 12 to the transporter module 14.

The L-shaped member also includes a second surface 74b which is arranged to abut against the outer side 100a of said downwardly depending wall portion of said micro titre plate 100 when the transporter module 14 is locating a micro titre plate 100 into a bay 26 of a hotel module 12. This action will be described in more detail subsequently.

It will be appreciated that the gap 76 between the first surface 74a of the holding and positioning means 74 and the rear side of the engaging portion 72a of the engaging member 72 will vary depending on the operational condition of the solenoid 75. When the solenoid 75 is"on"the gap 76 will be large as compared to when the solenoid is"off". This large gap 76 is required when locating or removing the downwardly depending side wall portion of the micro titre plate from the engaging member. The large gap 76 makes location and removal of the micro titre plate 100 easier whilst also allowing different sized micro titre plates 100 to be accommodated.

The carriage member 71 is arranged for substantially horizontal linear movement in the direction of the z-axis. To this end, the carriage member 71 includes a bearing arrangement 78 (Figure 5) which is arranged to enable the carriage member 71 to move smoothly along the length of the side walls of the elongate aperture 63. Movement of the engaging unit 70 is caused by a driving wire 73 which passes around a series of pulleys 77 mounted on the underside of the carriage member 71 and through a pair of apertures 71 a located in a

depending portion 71 b of the carriage member. A stepping motor 85 drives the driving wire 73 so as to cause horizontal linear movement of the carriage member 71 between a first forward position in which the engaging portion 72 can engage the inner side of a downwardly depending wall portion of a micro titre plate 100, and a second rearward position in which the micro titre plate 100 is fully received on the loading platform 62.

The liquid aspiration and dispensing station 10 is controlled by a system computer (not shown) and a number of microprocessors (not shown). During operation of the liquid aspiration and dispensing station 10, the transporter module 14 is signalled to move to a position into the front of the hotel module 12 so that it can select a desired micro titre plate 100 from one of the bays 26. The transporter module 14 may be instructed to select micro titre plates 100 in a specific order, or alternatively, it may select individual micro titre plates 100 as instructed. A barcode system and bar code reader 200 mounted on the transporter module 14 may be provided to enable specific bays 26 within the hotel module 12 and specific micro titre plates 100 to be identified. This means that a micro titre plate 100 can be picked up from any position on the liquid aspiration and dispensing station 10 and identified by the bar code reader 200.

Upon receiving a signal to pick up a micro titre plate 100 from the hotel module 12, the transporter module 14 is driven along the x-axis to the required position in front of the hotel module 12 by the stepping motor 51 b. The transporter module 14 is then driven by the stepping motor 51 a vertically along the column 50 or y-axis, so that the transporter module 14 is at the required height to access a particular micro titre plate 100 within one of the bays 26. The required height is determined by the need for the engaging member 72 to be able to pass underneath the lowermost bottom edge of the micro titre plate 100 without striking the micro titre plate 100.

Once the engaging member 72 is located below the micro titre plate 100 and the solenoid 75 is in the"on"condition, an upward adjustment of the transporter

module 14 along the column 50 is made. The upward adjustment is such that there is sufficient overlap between the inner side of the depending wall portion 100a of the micro titre plate 100 and the engaging portion 72a of the engaging member 72. The overlap between the depending wall portion 100a of the micro titre plate 100 and the engaging portion 72a is sufficient when the overlap is such that movement of the carriage member 71 from the first forward position to the second rearward position results in the micro titre plate 100 being slid from its bay 26 onto the loading platform 62 of the transporter module 14.

When the engaging member 72 is correctly positioned behind the inner side of the depending wall portion 100a of the micro titre plate 100, the solenoid 75 is switched to the"off"condition so that the first surface 74a of the holding and positioning means 74 moves towards the engaging member 72 and is thereby pressed against the outer side of the downwardly depending side wall portion 100a of the micro titre plate 100. In this manner, the depending wall portion 100a of the micro titre plate 100 is located or locked between the engaging portion 72a of the engaging member 72 and the holding means 74. When the holding and positioning means 74 is in position to hold the depending wall portion 100a of the micro titre plate 100, the carriage member 71 is driven from the first forward position to the second rearward position by the action of the drive wire 73 and the stepping motor 85. As the drive plate 71 is driven to the second rearward position, the micro titre plate 100 is slid from the bay 26 of the hotel module 12 to a position on the loading platform 62.

The micro-processor 80 is alerted to the fact that the micro titre plate 100 is safely in position on the loading platform 62 by virtue of a signal sent from a limit switch 90. If the micro-processor 80 does not receive the signal from the limit switch 90 within a set period of time after activation of the solenoid 75, the micro-processor 80 will provide a warning signal to the control software of the main computer. Failure to receive a signal from the limit switch 90 is likely to indicate that there was no micro titre plate 100 in the bay 26 of the hotel module

12 or, alternatively, a micro titre plate 100 has become jammed somewhere along the length of the loading platform 62.

Once the micro titre plate 100 is safely located within the transporter module 14 it is driven along the column 50 (i. e. along the y-axis) to a pre-set travel height.

The transporter module 14 is then rapidly driven along the x-axis to a position in front of the delivery station 16. The final position of the transporter module 14 along the x-axis will depend on the positioning of the bay 16a in which the micro titre plate 100 is to be deposited.

To safely deposit the micro titre plate 100 in the bay 16a the transporter module must be located above the height of the bay 16a a sufficient distance to allow the micro titre plate 100 to be slid onto the surface of the bay 16a. This is achieved by activation of the stepping motor 85 which drives the carriage member 71 from the second rearward position to the first forward position. The solenoid 75 is then switched to the"on"position to release the depending side wall portion 1 00a from between the holding means 74 and the engaging portion 72a of the engaging member 72. As stated previously, when the solenoid 75 is in the"on"position, the gap 76 is at its largest, making it easier to obtain release of the micro titre plate 100. The height of the transporter module 14 is then adjusted downwardly along the column 50 or y-axis so as to clear the engaging portion 72a from behind the downwardly depending side wall portion 100a of the micro titre plate 100. The second surface 74b of the holding and positioning means 74 is then in horizontal alignment with the downwardly depending side wall portion 110a of the micro titre plate 100.

At this stage, the carriage number 71 is driven forward a small distance along the z-axis so that the second surface 74b of the holding and positioning means 74 pushes the micro titre plate 100 forward and into its proper position on the bay 16a. The carriage member 71 is then retracted rearwardly along the z-axis until a second signal means 92 signals to the micro processor 80 that the solenoid 75 is in the zero or home position.

The transporter module 14 can then be rapidly driven along the x-axis to collect another micro titre plate 100 from the hotel module 12 or from another bay 16a in the delivery station 16.

Given that the micro titre plate 100 is safely located on the loading platform 62 of the transporter module 14 and between the sidewalls 64 and top stop plates 66, it is possible to move the transporter module 14 quite rapidly. There is no risk of the micro titre plate 100 being inadvertently dislodged or displaced because of the manner in which it is positioned and supported on the loading platform 62. As the transporter module 14 can move rapidly up and down the column 50 or y-axis, the number of micro titre plates 100 which can be selected from the hotel module 12, transported to the delivery station 16, aspirated by the delivery head 18 and then returned to the hotel module 12 in a set period of time is very high as compared with prior art systems. Consequently, a liquid aspiration and dispensing system in accordance with an embodiment of the invention will have an extremely high output capacity.

The micro titre plates 100 described previously have not included lids. However it is envisaged that lids may be used on the micro titre plates 100 and that a device for removing and storing the lids could be provided. The hotels 12a, 12b and transporter module 14 would be arranged to receive micro titre plates 100 with or without their lids.

The various components of the liquid aspiration and dispensing station 10 can be arranged to receive micro titre plates 100 of varying forms. It is envisaged that micro titre plates 100 of different forms including deep well micro titre plates may be used in the station 10 at the same time.

By using a bar code system and bar code reader it will be possible to track and identify any micro titre plate 100 used in the liquid aspiration and dispensing station 10. This means that micro titre plates 100 can be loaded and unloaded

from the hotel module 12 in any order desired. It also means that a particular micro titre plate 100 can be located no matter where it is currently positioned with the station 10. This"random"selection feature of the station 10 is seen to be of particular advantage.

The embodiments have been described by way of example only and modifications within the spirit and scope of the invention are envisaged.

The discussion of the background to the invention herein is included to explain the context of the invention. This is not to be taken as an admission that, any of the material referred to was published, known or part of the general knowledge in Australia as at the priority date.