WO2002055201A2

WO2002055201A2 - Sample processing apparatus

Info

Publication number: WO2002055201A2
Application number: PCT/GB2002/000122
Authority: WO
Inventors: Philip Andrew Davies; Darrin Matthew Disley; Aled Wynne Jones; Duncan Ross Purvis; Martin Gregory Beckett; Nicholas Miller; David Nicholas Miller-Jones
Original assignee: Scient Generics Ltd; Philip Andrew Davies; Darrin Matthew Disley; Aled Wynne Jones; Duncan Ross Purvis; Martin Gregory Beckett; Nicholas Miller; David Nicholas Miller-Jones
Priority date: 2001-01-12
Filing date: 2002-01-14
Publication date: 2002-07-18
Also published as: WO2002055201A3

Abstract

The present invention provides a system for processing biological or chemical samples. The system includes a support for supporting the sample and a mount which is movable relative to the sample by a positioner. The positioner includes a number of flexure elements which are rigid along their axis of extent and flexible along the or each axis of extent of the other flexure elements. The flexure elements are rigidly secured at one of their ends to the mount and displaceably mounted at the other of their ends to an actuator which is operable to move the flexure element and hence move the mount.

Description

SAMPLE PROCESSING APPARATUS
This invention relates to an apparatus for processing chemical and/or biological samples and a positioner that can be used in such an apparatus. The invention has particular, but not exclusive, relevance to a microarraying device for depositing patterns of chemical or biological samples on a substrate and a micro-manipulator for addressing a probe to previously deposited samples.

Micro-arraying devices are commonly used in the highthroughput analysis of test samples, typically new chemical or biological products, to identify potential therapeutic properties. In particular, the microarraying device deposits an array of indicator samples on a substrate, and the deposited array is then exposed to the test sample. Each of the indicator samples is associated with a corresponding property (such as protein binding) and produces a detectable effect, for example a change in the wavelength of a fluorescent label which is associated with the indicator sample, if the test sample exhibits the corresponding property.

There is a general trend towards using smaller quantities of the indicator samples and test samples, leading to a reduction in the cost associated with the indicator and test samples. Using small quantities of the test sample is particularly advantageous because frequently it is very expensive to produce the test sample and therefore only a small amount of the test sample is available.

Further, using smaller quantities of the indicator samples allows more indicator samples to be deposited within a fixed substrate area.

A micro-arraying device typically has a positioner which moves a dispensing head in order to dispense indicator samples on a substrate in the form of an array. The positioner is generally formed by a bearing-type positioner having three orthogonal positioning stages with each positioning stage moving along a corresponding bearing slide in response to drive signals applied to a motorised lead screw associated with the corresponding bearing slide. Such positioners have the disadvantage that the mass of movable parts makes them unsuitable for high speed positioning due to relatively high inertia.

Further, the bearing slides are prone to deterioration and imprecision and the lead screws introduce friction and backlash, making the positioners unsuitable for the high precision positioning which is desired with the reduction in sample sizes.

A micro-manipulator is used to place a probe adjacent to a particular test sample or adjacent an indicator sample which is to be exposed to the test sample. For example, in a patch clamping apparatus a patch pipette is placed on the membrane of a cell and clamped via a suction effect, and an electrode within the patch pipette detects small electrical signals generated by ions passing through ion channels in the clamped portion of the cell membrane. A problem with existing patch clamping apparatuses is the time required to position the patch pipette onto the cell membrane, and this problem is exacerbated by slow or imprecise movement of the glass pipette.

According to the present invention, there is provided an apparatus for processing chemical and/or biological samples having a positioner comprising a base member and a platform which are movable relative to each other, and at least one actuator which includes a flexure element connected between the platform and the base member. The use of a flexure element instead of a bearing slide is advantageous because it allows for greater precision of movement.

Positioners using flexure elements are used in applications such as aligning optical components and atomic force microscopy. However, in these known applications the required range of movement is significantly smaller than the required range of movement for apparatuses for processing biological and/or chemical samples. In an embodiment of the present invention, the apparatus includes both a first positioner which uses bearings and a second positioner which use flexure elements. The positioner using bearings is used to achieve course positioning over a relatively large range of movement, while the positioner using flexure elements is used to achieve higher precision positioning over a relatively small range of movement.

In an embodiment, the platform is movable in two or more different directions. Preferably, the flexure elements associated with each of the two or more different directions act in a parallel, rather than serial, fashion. This is advantageous because the mass which is moved is low for all directions of movement of the platform and therefore the positioner is better suited to high speed positioning. In contrast, in a conventional bearing-type positioner the bearing for a first translation stage is mounted on a second translation stage, i. e. the first and second translation stages are mounted in series. For such a bearing-type positioner, if the second translation stage is moved then the mass of the first translation stage must be moved in addition to the mass of the platform, thereby increasing the inertia of the system.

Preferably, an anti-rotation mechanism is provided to resist rotation of the platform about a desired direction of movement.

According to a second aspect of the present invention, there is provided a positioner having a plurality of actuators for causing relative movement between a base assembly and a platform, with each actuator including a respective flexure member connected between the base assembly and the platform, wherein the positioner further includes an anti-rotation mechanism formed by serial connection of a plurality of linkages which allow a single degree of freedom of movement along respective different linear directions. Such an anti-rotation mechanism prevents rotation of the platform about a desired direction of movement.

Preferably, each linkage is formed by a parallel pair of flexure leaves which have a low mass while maintaining a high resistance to torsional movement.

Various embodiments will now be described with reference to the attached drawings in which:
Figure 1 shows a perspective view of a micro-arraying device;
Figure 2 schematically shows components of a positioner forming part of the micro-arraying device illustrated in
Figure 1;
Figure 3 shows a flexure member which forms part of the positioner illustrated in Figure 2;
Figure 4 schematically shows in more detail the mechanism used by the positioner illustrated in Figure 2 to move a platform in one direction;
Figure 5 is a block diagram showing control circuitry forming part of the micro-arraying device illustrated in
Figure 1;
Figures 6A to 6C show how an anti-rotation mechanism of the positioner illustrated in Figure 2 resists rotational movement of the platform during movement in more than one direction ;

Figure 7 schematically shows-a-dispensing nozzle of the micro-arraying device illustrated in Figure 1;
Figure 8 shows a glass slide with sample arrays deposited thereon by the micro-arraying device illustrated in
Figure 1;
Figure 9 shows in more detail a sample array produced on the glass slide illustrated in Figure 8;
Figure 10 is a flow chart showing a typical drug development process;
Figure 11 shows a perspective view of a microperfusion chamber assembly and a patch pipette forming part of a patch clamping apparatus; and
Figure 12 shows control circuitry associated with a positioner for positioning the patch pipette relative to a cell within the microperfusion chamber illustrated in
Figure 11.

As shown in Figure 1, a micro-arraying device 1 forming a first embodiment of the invention has a base 3 and is positioned in use on a table 5 via four anti-vibration feet, three of which are visible in Figure 1 referenced 5a to 5c. In use, a shield (not shown) also surrounds the screening apparatus 1 to prevent vibrations caused by air currents.

A worktop 7 is mounted on an X-direction translation stage 9, which is in turn mounted on a Y-direction translation stage 11 that is mounted on the base 3. A head device having a housing 13 is mounted on a Zdirection translation stage 15, which is in turn mounted on the base 3. As shown, each of the translation stages 9,11 and 15 moves along a respective bearing slide 17a, 17b, 17c having a dove-tail profile. The translation stages are driven along the bearing slides 17 by respective motorized lead screws (not shown).

In this embodiment, the translation stages 9,11 and 15 are used only to provide coarse alignment between the worktop 7 and the head device, and a positioner (not shown in Figure 1) within the head device is used for fine alignment.

The micro-arraying device 1 forms arrays of indicator samples on a glass slide 19 located on the worktop 7.

In order to do this, the micro-arraying device 1 inserts, using the translation stages 9,11 and 15, a dispensing nozzle 21 into an indicator sample container, four of which are shown in Figure 1 referenced 23a to 23d, and then moves, again using the translation stages 9,11 and 15, the dispensing nozzle 21 to a predetermined area of the glass slide 19. The positioner within the head device 13 then moves the dispensing nozzle 21 to form the array of test samples on the glass slide 19.

The positioner within the head device will now be described with reference to Figures 2 to 6.

As shown in Figure 2, the positioner 31 has a fixed part 33, which is fixed relative to the housing 13 of the head device, and a movable part 35 having a surface 37 which forms a platform for mounting the dispensing nozzle 21.

The positioner 31 is shown inverted in Figure 2 compared to its orientation when mounted to the head device. In this embodiment, the movable part 35 is formed in the shape of a cube with a projecting portion 36 provided adjacent one corner of the cube. The movable part 35 is made from aluminium and weighs approximately 100g.

A first voice coil 39a is connected to the movable part 35 via a first flexure member 41a and is mounted on a first upstanding member 43a forming part of the fixed part 33 (in Figure 2 part of the first upstanding member 43a has been cut away to reveal more fully the first voice coil 39a). The first voice coil 39a is operable to move, via the first flexure member 41a, the movable part 35 in the X-direction relative to the fixed part 33.

Similarly, a second voice coil 39b is connected to the movable part 35 via a second flexure member 41b and is mounted on a second upstanding member 43b, forming part of the fixed part 33, so that the second voice coil 39b is operable to move the movable part 35 in the Y direction relative to the base part 33. A third voice coil 39c is connected to the movable part 35 via a third flexure member 41c and is mounted to the fixed part 33 so that the third voice coil 39c is operable to move the movable part 35 in the Z-direction relative to the fixed part 33.

The interaction between the voice coils 39, the flexure members 41, and the movable part 35 will now be described in more detail with reference to Figure 3 to 5.

Figure 3 shows in detail one of the flexure members 41.

As shown, the flexure member 41 has an elongate central portion 61 and two end portions 63a, 63b respectively connected to the longitudinal ends of the central portion 61 by two flexible portion 65a, 65b. The central portion 61 and the end portions 63 are made of stainless steel rod having a circular cross-section with a diameter of 3mm. The central portion 61 is 25mm long while each of the end portions 63 is 10mm long.

Each of the flexible portions is a 30mm length of 1mm diameter music wire, of which 10mm at each end is embedded within either the central portion 61 or the respective end portion 63 leaving a free section of 10mm. Each flexure member 41 is substantially rigid in respect of forces applied along its longitudinal axis, but deformable in respect of forces applied perpendicular to its longitudinal axis.

Figure 4 shows in more detail the interaction between a voice coil 39 and the movable part 35 via a flexible member 41. As shown, the voice coil 39 has a stator 71 and an armature 73. The stator 71 is a permanent magnet which is attached to the fixed part 33 and is generally cylindrical with a circular cross-section apart from an annular-shaped recess. The armature 73 has a cylindrical portion 75 with an annular cross-section which is shaped so that the armature 73 is slidably mounted within the annular shaped recess of the stator 71 to allow relative movement between the stator 71 and the armature 73 along the direction marked A in Figure 4.

An end portion 77 of the armature 73 is connected to the end of the cylindrical portion 75 away from the stator 71 and a wire 79, which is connected to control circuitry (not shown in Figure 4), is wrapped around the cylindrical portion 75.

As shown in Figure 4, one of the end portions 63a of the flexure member 41 is embedded within the end portion 77 of the armature 73, while the other end portion 63b of the flexure member 41 is embedded within the movable part 35. In this way, passing an electric current through the wire 79 causes the armature 73 to move relative to the stator 71 along the direction of movement A, either away from the stator 71 or towards the stator 71 depending upon the direction of the flow of current through the wire 79, and the movement of the armature 73 is transferred to the movable part 35 by the flexure member 41.

In this embodiment, each flexure member 41 has a corresponding conventional position encoder 81 which monitors the position of the movable part 35. Each position encoder 81 is connected to the control circuitry which varies the current passing through the wire 79 of the corresponding voice coil 39 in dependence upon signals received from the position encoder 81 to ensure accurate positioning of the movable part 35. In other words, a closed loop control system is used to control the positioning of the movable part 35.

Figure 5 schematically shows the main components of the control circuitry used in this embodiment. As shown, a personal computer (PC) 91, via which a user specifies a desired operation for the micro-arraying device, is connected to a controller 93. Typically, the PC 91 will instruct the controller to move the dispensing nozzle 21 to a series of positions relative to the worktop 7.

In order to position the dispensing nozzle 21 relative to the worktop 7 coarsely over longer distances, the controller 93 outputs control signals to three motor drivers 95a to 95c, which outputs corresponding drive signals to an X-direction drive motor 97a, which drives the lead screw moving the X-direction translation stage 9 along its corresponding bearing slide 17a, a Ydirection drive motor 97b, which drives the lead screw moving the Y-direction translation slide 11 along its corresponding bearing slide 17b, and a Z-direction drive motor 97c, which drives the lead screw moving the Z- direction translation stage 15 along its corresponding bearing slide 17c.

The controller 93 is also connected, via respective amplifier stages 99a to 99c, to the voice coils 39. In order to cause the dispensing nozzle 21 to move in intricate patterns over shorter distances, the controller 93 outputs control signals to the amplifier stages 99 which generate corresponding drive signals which are output to the voice coils 39. The position encoders 81 are connected to the controller 93 and output feedback signals indicative of the actual position of the movable part 35 relative to the fixed part 33 of the positioner 31.

Returning to Figure 2, the positioner 31 also includes an anti-rotation mechanism 45 which prevents: (i) rotation of the movable part 35 about the X-direction, which will hereafter be referred to as rolling of the movable part 35; (ii) rotation of the movable part 35 about the Y-direction, which will hereafter be referred to as pitching of the movable part 35; and (iii) rotation of the movable part 35 about the Z-direction, which will hereafter be referred to as yawing of the movable part 35. The terms rolling, pitching and yawing are used purely for ease of reference and are not intended to imply any additional features beyond those described.

The anti-rotation mechanism 45 includes three linkages connected in series between the fixed part 33 and the movable part 35. Each of the linkages is formed by a pair of parallel flexure leaves 47 which allow only one degree of freedom of movement. In this embodiment, the flexure leaves 47 are rectangular strips of stainless steel having a thickness of 0. 15mm.

The first pair of flexure leaves 47a, 47b link the projecting portion 36 of the moving part 35 to a first block 49. In particular, the first pair of flexure leaves 47a, 47b are spaced apart at each longitudinal end by a respective one of the projecting portion 36 and the first block 49 so that they are parallel. Each of the first pair of flexure leaves 47a, 47b lies generally within a plane perpendicular to the Y-direction and has its lengthwise direction generally in the X-direction.

As a result, the first pair of flexure leaves 47a, 47b can flex in response to movement of the movable part 35 in the Y-direction.

The second pair of flexure leaves 47c, 47d are connected at each longitudinal end to a respective one of the first block 49 and a second block 51, which space apart the second pair of flexure leaves so that they are aligned parallel to each other within planes generally perpendicular to the X-direction and with their lengthwise directions generally in the Z-direction.

Similarly, the third pair of flexure leaves 47e, 47f are connected at each longitudinal end to a respective one of the second block 51 and a third block 53, which space apart the third pair of flexure leaves 47e, 47f so that they are aligned parallel to each other within planes generally perpendicular to the Z-direction and with their lengthwise directions generally in the Y-direction. As a result of their construction, the second pair of flexure leaves 47c, 47d can flex in response to movement of the movable part 35 in the X-direction and the third pair of flexure leaves can flex in response to movement of the movable part 35 in the Z-direction.

The third block 53 is mounted to a fourth block 55 which forms part of the fixed part 33, with the lower flexure leaf 47f of the third pair of flexure leaves 47e, 47f (as shown in Figure 2) sandwiched between the third block 53 and the fourth block 55. The purpose of the fourth block 55 is to space the lower flexure leaf 47f from the planar base of the fixed part 33 to allow room for the lower flexure leaf 47f to flex in the Z-direction towards the planar base.

As described above, each of the serial linkages only allows movement of the movable part 35 in a respective different linear direction. Further, as a result of their shape the linkages resist torsional forces, thereby resisting rolling, pitching and yawing of the movable part 35.

Figures 6A to 6C show plan views of the positioner 31 illustrating how the flexure members 41 and the flexure leaves 47 of the anti-rotation mechanism 45 deform as the movable part 35 is moved. In Figure 6A, the movable part 35 is positioned so that none of the flexure members 41 nor the flexure leaves 47 are flexed. This will be referred to as the neutral position.

In Figure 6B, the movable part 35 has been moved from the neutral position in the Y-direction by passing a current through the wire 79 wrapped around the armature 73 of the second voice coil 39b. This movement has caused the first flexure member 41a, connecting the first voice coil 39a to the movable part 35, and the first and second flexure leaves 47a, 47b to flex in order to accommodate this movement. In Figure 6C, the movable part 35 has been moved in the X-direction from the position illustrated in Figure 6B by passing an electric current through the coil wrapped around the armature of the first voice coil 39a. This has caused the second flexure member 41b and the third and fourth flexure leaves 47c, 47d to flex in order to accommodate the movement of the movable part 35.

The level of flexing shown in Figures 6B and 6C is significantly higher than that which would occur in a typical application in order to illustrate the flexing more clearly.

As described previously, a dispensing nozzle 21 is mounted on the platform 37 of the movable part 35. In this embodiment, the dispensing nozzle 21 is a TeleChem ChipMaker micro-spotting pin, which is generally described in US Patent No. 6,101,946 whose contents are incorporated herein by reference.

Figure 7 shows the dispensing end of the dispensing nozzle 21. As shown, the dispensing nozzle 21 is tapered to a flat tip 111 and a capillary 113 is provided from the flat tip 111 to a reservoir 115. When the flat tip 111 is immersed in a sample solution, a small amount of the sample solution is sucked up through the capillary 113 into the reservoir 115, with some of the sample solution remaining on the flat tip 111. The dispensing nozzle is then able to deposit small volumes of the sample solution onto a substrate by bringing the sample solution on the flat tip 111 of the micro spotting pin into contact with the substrate. After the sample solution on the flat tip 111 has been deposited onto the substrate, it is replaced by some of the sample solution stored in the reservoir 115.

In this way, precisely controlled amounts of sample solution can be repeatedly deposited onto a substrate.

Figure 8 shows the glass slide 19 after samples have been deposited on its surface by the micro-arraying device 1.

The glass slide 19 is rectangular with a length of approximately 76mm and a width of approximately 25mm.

At one longitudinal end of the glass slide a bar code 121 is formed identifying the samples provided on the glass slide 19. In this embodiment, an array of wells 123 are formed in the glass slide 19, with each well 123 being square with sides 2mm long and having a depth of 1mm.

Prior to depositing samples, the surface of the glass slide 19 is treated so that the sample will physically attach itself to the glass slide 19. This is required to prevent the sample being washed away during slide processing. Further, the surface of the glass slide 19 is made hydrophobic, contrary to an untreated slide which is hydrophilic, because this allows a higher sample density because the samples spread less on the glass slide 19.

Within each of the wells 123 a ten-by-ten array of samples is formed, using the high resolution positioner 31 of the micro-arraying device 1. An enlarged view of the sample array is shown in Figure 9. As shown, the samples 131 have been deposited as a regular two dimensional array having a pitch p (i. e. the distance between the centres of neighbouring samples) of approximately 100 microns, accurate to approximately 1 micron. Each sample is approximately circular with a diameter of 75 microns.

In use, the micro-arraying device 1 can deposit biological samples such as olignucleotides, peptides, anti-bodies and mammalian cells. Alternatively, the micro-arraying device can deposit chemical samples including volatile (i. e. low molecular weight) or nonvolatile (i. e. high molecular weight) samples and potential drug candidates such as potential non-steroidal anti-inflammatory drugs.

Figure 10 is a flow chart illustrating a typical drug development process. Firstly, in step Sl a new sample is prepared and then the new sample is tested, in step
S3, for potential therapeutic properties. According to one aspect of the invention, the testing for potential therapeutic properties includes using the micro-arraying device 1 to produce a sample array and subsequently testing the new sample using the sample array.

If no potential therapeutic property is discovered, the process ends, whereas if a potential therapeutic property is discovered, clinical drug development is performed in step S5. There are many reasons why a drug entering clinical development does not result in a commercial product. For example, the drug could have an adverse side effect or could be prohibitively expensive to manufacture commercially. If the new samples does not satisfy, in step S7, the requirements for commercial manufacture then the drug development process ends. If, however, the clinical drug development is successful then a drug is commercially manufactured in step S9.

Those skilled in the art will appreciate that an analogous development process is performed for biological products.

In the first embodiment, a micro-arraying device 1 has a positioner 31 which uses flexure elements instead of bearing slides in order to allow fast and accurate positioning of a dispensing nozzle 21. A second embodiment will now be described in which the positioning system of the first embodiment (i. e. the coarse positioner formed by the translation stages 9,11,15 and the flexure positioner 31 for high-resolution, high-speed positioning) forms part of an automatic patch clamp apparatus. In the second embodiment, the positioner 31 moves a patch pipette onto a cell membrane and therefore acts as a micro-manipulator.

A general description of an automatic patch clamp apparatus can be found in International Patent
Publication No. WO 98/50791 whose contents are hereby incorporated by reference. The only difference between the second embodiment and the automatic patch clamp apparatus described in WO 98/50791 is that the positioning system of the first embodiment (i. e. the
X, Y, Z, translations stages 9,11,15, the flexure positioner 31 and associated control circuitry) are used to position the patch pipette onto a cell membrane.

Figure 11 illustrates a microperfusion chamber assembly 151 which is used in the patch clamp apparatus described in WO 98/50791. As shown, the microperfusion chamber assembly is formed by a ring-shaped disc 153 which is formed of silver so that it can serve as a reference electrode. A silver wire 155 is soldered to the disc 153, and the disc 153 is coated with a thin layer of silver chloride to prevent electrical shorting between the disc 153 and a test electrode. The hole 157 through the centre of the disc 153 is formed into a microperfusion chamber by attaching a glass cover slip 159 to one side of the disc 153. An inlet pipe 161 opens into the microperfusion chamber to introduce sample solutions into the microperfusion chamber, and an outlet pipe 163 is provided to remove excess sample solution.

In use, a layer of cells is formed on a small cover slip which is then placed at the bottom of the microperfusion chamber. Then, as shown in Figure 11, a patch pipette 165 is placed within the microperfusion chamber by using the coarse positioner to move the patch pipette.

Figure 12 shows the main components of control circuitry within the patch clamp apparatus for placing the patch pipette 165 on the wall of a cell. As shown, a camera 171, which images the cells in the microperfusion chamber and the tip 167 of the patch pipette 165, sends image data to a processor 173 which applies image recognition algorithms to the received image data to determine the positions of the tip 167 and the cells. The processor 173 then selects an appropriate cell to be probed. This image processing is described in more detail in WO 98/50791.

After a cell has been selected, the processor 173 sends control signals to the voice coils 39 of the positioner 31, via their respective amplifier 175, to move the tip 167 of the patch pipette 165 to the membrane of the selected cell. The patch pipette 165 is then clamped to the cell membrane by applying a small suction force through the patch pipette 165. In this embodiment, the test electrode is incorporated within the patch pipette 165 so that when a sample solution is introduced via the inlet pipe 161, small electrical signals generated by ions passing through ion channels in the cell membrane can be monitored.

Those skilled in the art will appreciate that the pharmacological and toxicological activity of potential drug candidates is driven by ion channel activity. For example, many potential pharmaceutical candidates fail at a late stage during clinical drug development because they block HERG-MiRP channels regulating Potassium flux resulting in a prolongation of the QT interval of ECG of mammalian heart cells. The patch clamp apparatus can therefore be used to profile potential drug candidates for cardiotoxicity prior to their selection as lead compounds for progression into expensive clinical drug development programmes.

Modifications and Further Embodiments
In the first embodiment a flexure positioner 31 is incorporated within a micro-arraying device, whereas in the second embodiment an identical flexure positioner is incorporated within an automatic patch clamping apparatus. In a preferred embodiment, the flexure positioner 31 forms part of a multi-function device. In particular, the multi-function device has a plurality of process devices which can be detachably mounted to the flexure positioner in dependence on the desired function.

Thus, if micro-arraying is desired a micro-spotting pin is attached to the flexure positioner whereas if patch clamping is desired a patch pipette is attached to the flexure positioner. Further, a field stimulation probe could be used which stimulates a sample by applying an electric, magnetic or electromagnetic field. For example, if it is desired to irradiate a sample with light, an optical head is mounted to the flexure positioner. Typically, such an optical head would include an optical fibre having an end which is aligned with the sample using the flexure positioner.

In the first embodiment a micro-spotting pin is used to deposit a sample array onto a substrate. Those skilled in the art will appreciate that more than one microspotting pin could be attached to the flexure positioner, so that a plurality of samples can be deposited in parallel. Further, the described micro-spotting pin could be replaced by an alternative dispensing pin, for example a split pin, or by a discharge nozzle which, for example, uses a piezo-electric actuator to discharge a sample onto a substrate.

Those skilled in the art will appreciate that instead of mounting a process device such as the micro-spotting pin and the patch pipette onto the flexure positioner, the substrate or sample could be mounted on the flexure positioner with the process head being maintained stationary. Further, although in the first embodiment the worktop is moved in the X and Y-directions by translation stages and the dispensing nozzle is moved in the Z-direction by a translation stage, the same relative movement is achievable by, for example, mounting either the worktop or the dispensing nozzle on three translation stages for movement in the X, Y, and Z-directions.

In an alternative embodiment, more than one flexure positioner 31 is incorporated in an apparatus for processing chemical or biological samples, allowing samples to be excited while simultaneously detecting phenomena related to the excitation. For example, a first optical head mounted on a first flexure positioner could illuminate, via an optical fibre, a sample on a transparent substrate from one side of the substrate while a second optical head mounted on a second flexure positioner detects the fluorescence emitted by the sample from the other side of the transparent substrate, if necessary using filters to filter out light emitted by the first optical head.

In the first embodiment, the micro-arraying device forms an array of samples each having a diameter of 75 microns onto a substrate. Those skilled in the art will appreciate that there are already available dispensing elements which can form smaller sample sizes than this.

As liquid handling systems improve, it can be expected that the minimum sample spot size will decrease even further. It will be appreciated that the flexure-type positioners are particularly well-suited to handling such small sample spot sizes due to their high level of precision.

In the first embodiment, there is described depositing the sample array into a well having a depth of 1 mm and sides of length 2mm. This well size is given for exemplary purposes only and, for example, smaller well sizes could be used. Preferably, the sides of the well have a length in the range of 0.5mm to 2mm and the depth of the well is in the range 0.25mm to lmm.

Those skilled in the art will appreciate that the microarraying device of the first embodiment could also be used to deposit an array of proteins which each give an indication of a particular disease state (sometimes referred to as diagnostic markers), proteins which give an indication of a genetic sequence variation, or a synthetic-ligand that binds with high-affinity. The micro-arraying device therefore has application in highdensity DNA sequencing, protein identification and biomolecular screening analysis.

In the first embodiment, the position of the dispensing nozzle 21 relative to the fixed part 33 of the flexure positioner 31 is accurately known due to the position encoder 81. If the position of the tip of the dispensing nozzle 21 relative to the substrate is accurately known, then it is possible for the dispensing nozzle to dispense a first sample, move using the coarse positioner to collect a different sample, and then either re-address the position of the first sample or deposit a second sample at a precise position relative to the first sample.

One way of accurately detecting the position of the dispensing nozzle relative to the substrate is to use an imaging system, such as the imaging system mentioned in the second embodiment. If such an imaging system is used, then preferably the substrate includes a number of fiducial markers (for example cross-hairs) which aid the image processing. Provided that the coarse positioner is able to position the dispensing nozzle close to one of the fiducial markers, the flexure positioner can then be used accurately to position the dispensing nozzle relative to the fiducial marker.

In the first embodiment, each position encoder 81 is located adjacent to a corresponding flexure member 41.

Alternatively, each position encoder 81 could be located adjacent to a corresponding armature 73, which is advantageous because the distance between the armature 73 and the position encoder 81 remains constant whereas the distance between the flexure member 41 and the position encoder 81 of the first embodiment will vary as the flexure member 41 flexes.

The flexure positioner 31 used in the first and second embodiments uses an anti-rotation mechanism in which rotation of the movable part 35 is prevented by three linkages connected in series between the fixed part 33 and the movable part 35, with each linkage allowing movement of the movable part in a single linear direction. The positioner 31 could also be used in other devices which require precision positioning. For example, the positioner 31 could be used in an atomic force microscope or to align optical components such as optical waveguides.

In the described embodiments the linkages of the antirotation mechanism are formed by pairs of flexure leaves.

This is not essential, however, because the linkages could alternatively be formed using bearings. For example, the movable part could be mounted to an Xdirection bearing slide having a square cross-section so that the movable part is only able to move in the Xdirection, and the X-direction bearing slide could in turn be mounted to a Y-direction bearing slide only allowing movement in the Y-direction, and the Ydirection bearing slide could in turn be mounted on a Zdirection bearing slide only allowing movement in the Zdirection. However, the use of bearings in the antirotation mechanism is not preferred because they introduce friction, can lead to imprecision and add extra mass to the movable part giving a rise in inertia and therefore a reduction in speed.

The positioner 31 is operable to move a tool attached to its platform in three dimensions. If, however, the positioner were only able to move the tool in two directions, then the anti-rotation mechanism need only have two linkages.

Those skilled in the art will appreciate that it is not essential for the directions of movement of the movable part to be orthogonal. Further it is not essential for each of the linkages of the anti-rotation mechanism to be aligned so that its associated direction of movement is aligned with the direction of movement of one of the actuators.

In the described positioner 31, the movable part 35 is made from aluminium which is advantageous due to its rigidity, low density and ease of manufacture. However, the movable part could be made from other substances such as glass filled nylon. Further, the flexure leaves need not be made from stainless steel as they could also be made, for example, from a Beryllium-Copper alloy.

Preferably, the weight of the movable part 35 is less than lOOg unladen, and is less than 200g when carrying the process device or substrate so that the relatively low inertia allows high speed operation.

The positioner 31 has a range of movement of approximately lmm in each direction. With suitable engineering, however, this range of movement could be increased to at least 10mm.

The voice coils 39 are advantageous because they are virtually friction-free and are also highly controllable.

Although in the described embodiment, the stator is formed by a permanent magnet and wire is wrapped around the armature, alternatively the armature could be formed by the permanent magnet with the wire wrapped around the stator. Further, an electro-magnet could be used in place of the permanent magnet.

If only a very small range of movement is desired, then piezo-electric actuators could be used in place of the voice coils.

The flexible parts 65 of the flexure elements 41 connecting the voice coils 39 of the described flexure positioner 31 to the movable part 35 are formed by music wire. Alternatively, the flexible parts could be formed by grinding a steel rod to provide sections having a thinned cross-section.

Those skilled in the art will appreciate that the movable part will not generally be cuboid, but will rather be the smallest shape which satisfies the operational requirements of the positioner. For the described antirotation mechanism using pairs of flexure leaves, one of these requirements is that the moving part 35 includes a portion which can act as a spacer element which, in combination with the first block 49, aligns a pair of flexure leaves parallel to each other. The shape of the first, second and third blocks of the anti-rotation mechanism can also be adjusted to suit a particular operational requirements.

In an apparatus for processing chemical or biological samples, many of the advantages attained by using the described flexure positioner 31 can also be attained by using a conventional flexure positioner such as those described in UK Patent Application Nos. 2129955 and 2334593.

Claims

CLAIMS 1. An apparatus for processing biological or chemical samples, the apparatus comprising: a support operable to support a biological or chemical sample; a mount operable to mount a process device for processing the biological or chemical sample; and a positioner operable to vary the relative position between the mount and the support, the positioner comprising: i) a first part which is fixed relative to the support; ii) a second part which is fixed relative to the mount;

and iii) a plurality of actuators each operable to cause relative movement in a respective different direction between the first and second parts, thereby causing relative movement between the support and the mount, wherein a plurality of flexure members are connected between the first part and the second part, each flexure member being operable to flex in response to relative movement of the first part and the second part as a result of the operation of one or more of the actuators.

2. An apparatus according to claim 1, wherein the positioner comprises two actuators which are operable to cause relative movement between the support and the mount in two dimensions.

3. An apparatus according to claim 1, wherein the positioner comprises three actuators which are operable to cause relative movement between the support and the mount in three dimensions.

4. An apparatus according to any preceding claim, wherein at least one of the plurality of actuators comprises a voice coil operable to cause relative movement between the first and second parts in response to a received drive signal.

5. An apparatus according to any preceding claim, wherein the plurality of actuators are arranged to cause relative movement the first and second parts in respective different orthogonal directions.

6. An apparatus according to claim 5, wherein each flexure member is connected between the first and second parts independently of any other flexure member.

7. An apparatus according to any preceding claim, wherein each flexure member is connected between a corresponding actuator and one of the first and second parts and is rigid along the direction of relative movement associated with the corresponding actuator but flexible along the direction of movement of the or each other actuator.

8. An apparatus according to claim 7, wherein the flexure member comprises an elongate rod having at least one thinned portion along its length so that the flexure member is rigid along the longitudinal direction of the rod but flexible in all other directions.

9. An apparatus according to claim 7 or 8, wherein the positioner further comprises an anti-rotation mechanism operable to resist relative rotational movement between the first and second parts.

10. An apparatus according to claim 9, wherein the antirotation mechanism comprises a plurality of linkages each having a single degree of freedom of movement connected in series between the first part and the second part with the degree of freedom of movement of each linkage being in a respective different linear direction.

11. An apparatus according to claim 10, wherein the degree of freedom of movement of each linkage is aligned along the direction of relative movement resulting from operation of a corresponding actuator.

12. An apparatus according to any of claim 10 or 11, wherein each linkage comprises a pair of flexure leaves with at least two spacers connected between the flexure leaves to maintain the flexure leaves parallel.

13. An apparatus according to any preceding claim, wherein at least one of the support and the mount are movably mounted on a bearing.

14. A system for processing biological or chemical samples, the system comprising: an apparatus as claimed in any preceding claim; and a process device mountable on the mount and operable to process a biological or chemical sample.

15. A system according to claim 14, wherein the process device comprises means for dispensing a quantity of the biological or chemical sample.

16. A system according to claim 15, wherein the dispensing means comprises a plurality of dispensing elements, each dispensing element being operable to dispense a quantity of the biological or chemical sample.

17. A system according to claim 14, wherein the process device comprises a probe operable to interact with the biological or chemical sample.

18. A system according to claim 17, wherein the probe comprises a patch clamp device.

19. A system according to claim 17, wherein the probe comprises an electrode operable to monitor electrical signals associated with the chemical or biological sample.

20. A system according to claim 17, wherein the probe comprises means for directing light onto the biological or chemical sample.

21. A system according to claim 17, wherein the probe comprises means for detecting light emitted by the biological or chemical sample.

22. A system according to claim 20 or 21, wherein the probe comprises an a light guide.

23. A system according to claim 22, wherein the light guide comprises an optical fibre.

24. A method of depositing a plurality of biological or chemical samples onto a substrate, the method comprising: supporting the substrate; supplying the biological or chemical sample to a dispensing device; and varying the relative position between the substrate and the dispensing device through a plurality of predetermined relative positions using a positioner comprising: i) a first part which is fixed relative to the substrate; ii) a second part which is fixed relative to the dispensing device; iii) a plurality of actuators each operable to cause relative movement in a respective different direction between the first and second parts, thereby causing relative movement between the substrate and the dispensing device;

and iv) a plurality of flexure members connected between the first part and the second part, each flexure member being operable to flex in response to relative movement of the first part and the second part as a result of the operation of one or more of the actuators; and at each of the plurality of predetermined positions, causing the dispensing head to deposit a quantity of the biological or chemical sample on the substrate.

25. A method according to claim 24, wherein the plurality of predetermined relative positions form a regular array.

26. A process of producing a biological or chemical product comprising: testing a plurality of biological or chemical samples to identify a test sample having a therapeutic property; developing a biological or chemical product from the identified test sample; and commercially manufacturing the biological or chemical product, wherein the testing of the test samples comprises: depositing a plurality of indicator sample on a substrate in accordance with the method claimed in claims 24 and 25, each indicator sample being associated with a corresponding property and producing a detectable effect when exposed to a chemical or biological sample exhibiting the associated property; exposing the plurality of indicator samples to each of the plurality of test samples;

and for each of the plurality of test samples, monitoring for the presence of the respective properties associated with each of the indicator samples.

27. A positioner comprising: a first part and a second part which are movable relative to each other by a plurality of actuators, each of the plurality of actuators being operable to cause relative movement between the first and second parts in a respective different direction via a respective transmission means;

and an anti-rotation mechanism operable to resist relative rotational movement between the first and second parts, wherein each transmission means comprises a flexure member connected between the first part and the second part, each flexure member being rigid along the direction of relative movement associated with the corresponding actuator and being flexible along the direction of relative movement associated with the or each other actuator, and wherein the anti-rotation mechanism comprises a plurality of linkages each having a single degree of freedom of movement connected in series between the first part and the second part with the degree of freedom of movement of each linkage being in a respective different linear direction.

28. A positioner according to claim 27, comprising two actuators which are operable to cause relative movement between the first and second parts in two dimensions.

29. A positioner according to claim 27, comprising three actuators which are operable to cause relative movement between the first and second parts in three dimensions.

30. A positioner according to any of claims 27 to 29, wherein at least one of the plurality of actuators comprises a voice coil operable to cause relative movement between the first and second parts in response to a received drive signal.

31. A positioner according to any of claims 27 to 30, wherein the plurality of actuators are arranged to cause relative movement the first and second parts in respective different orthogonal directions.

32. A positioner according to any of claims 27 to 31, wherein each flexure member comprises a single elongate rod having at least one thinned portion along its length so that the flexure member is rigid along the longitudinal direction of the rod but flexible in all other directions.

33. A positioner according to any of claims 27 to 32, wherein the degree of freedom of movement of each linkage is aligned along the direction of relative movement resulting from operation of a corresponding actuator.

34. A positioner according to any of claim 27 to 33, wherein each linkage comprises a pair of flexure leaves with at least two spacers connected between the flexure leaves to maintain the flexure leaves parallel.

35. An apparatus for processing biological or chemical samples, the apparatus comprising: a support operable to support a biological or chemical sample; a mount operable to mount a process device for processing the biological or chemical sample; and a positioner operable to vary the relative position between the mount and the support, the positioner comprising a plurality of flexure members arranged to extend along respective different axes, each flexure member being rigidly secured at one of its ends to one of the mount and the support and displaceably mounted at its other end to the other one of said mount and support via a respective associated actuator,

each flexure member being rigid along its axis of extent and flexible along the or each axis of extent of the or each other flexure member and wherein each actuator is operable to cause relative movement between the mount and the support in a direction corresponding to the axis of extent of the associated flexure member mounted thereto by applying an actuation force along the axis of extent of the associated flexure member.