WO2010133347A2

WO2010133347A2 - A nano-scale manipulator

Info

Publication number: WO2010133347A2
Application number: PCT/EP2010/003049
Authority: WO
Inventors: Diederik Johannes Van Der Zalm; Erwin Cornelis Heeres; Marinus Bernardus Stephanus Hesselberth; Allard Jules Katan; Maarten Hubertus Van Es
Original assignee: Universiteit Leiden; Technologiestichting Stw
Priority date: 2009-05-21
Filing date: 2010-05-19
Publication date: 2010-11-25
Also published as: WO2010133347A4; WO2010133347A3; GB0908780D0

Abstract

A nano-scale manipulator (10) comprises a mounting deck (11) and a frame (12), the deck (11) being moveably secured to the frame (12) by two flexural joints permitting movement of the deck relative to the frame in first and second respective, mutually orthogonal directions of movement. Manipulator (10) also includes at least one respective, elongate piezoelectric actuator (21, 22) for each of the flexural joints, each respective piezoelectric actuator (21, 22) being secured so as to interconnect the deck (11) and the frame (12) and being extensible and contractible in a direction that is parallel to one of the said directions of movement; and a source (23) of electrical power for causing operation of each piezoelectric actuator (21, 22). Each of the piezoelectric actuators (21, 22) also is free to flex in directions other than its direction of extension and contraction.

Description

A NANO-SCALE MANIPULATOR

This invention relates to a nano-scale manipulator.

In recent years the subject of nano-scale research has grown significantly in importance in the scientific community. The various branches of nanotechnology in which such research activities take place include (but are not limited to) the creation of probes, such as atomic force microscopy (AFM) tips, and field emission sources involving mounting carbon nanotubes; and the positioning of small structures with a very high accuracy (as for example in nano-diamond manipulation). The invention is of benefit in such areas of work, although use of the invention is not limited to the areas mentioned.

It is known to use various kinds of extremely high precision microscope for the purpose of imaging and/or otherwise analysing minuscule structures of the kind indicated above. Among other types, transmission electron microscopes (TEM's) and scanning electron microscopes (SEM's) are known. A characteristic of each of these microscope types is the inclusion of a vacuum chamber in which samples undergoing investigation are placed. An SEM or other high magnification microscope may also be used to observe the manipulation process during the preparation of an experiment or manufacture of a probe.

As a generality it is necessary when using such equipment to position the target samples with extreme accuracy. The requirement of accuracy however increases many fold when considering techniques such as the making of AFM probes. There is a need to manufacture enhanced AFM probes, involving mounting of a high aspect ratio carbon nanotube onto the end of an AFM tip, to obtain a probe that is subsequently used to study rough surfaces.

In the AFM technique a molecule, cell or other very small structure (that typically is a surface requiring investigation in the form of "exploration" at a nano-scale level) is contacted by a probe having a fine tip. Forces on the probe are then measured and used to construct topographical summaries, such as images, of the target structures.

When seeking to manoeuvre an AFM tip, eg. during manufacture, with accuracies commensurate with sub-molecular investigations, an almost inconceivably high degree of positioning accuracy is required. By way of illustration, one type of manipulator is known as the "stick-slip" type. In this arrangement three mutually orthogonally extensible actuators are arranged to cause movement of a holder in accordance with a phenomenon of hysteresis in the movement of the actuator parts. This hysteresis causes initial "sticking" of the actuator followed by sliding motion, the magnitude of which for a given input force theoretically is predictable.

The stick-slip manipulator type during operation oscillates at an amplitude that is greater than the increments of movement available. It follows that the stick-slip manipulator type, when considered on its own, is unsatisfactory in nano-scale manipulation processes since the target particle or structure (that normally is no bigger than a molecule) may be moved significantly "out of range" by the aforesaid oscillation; and collisions between the holder and the AFM tip may cause damage to the measuring equipment or target structure such that an investigation or manufacturing step must be aborted.

The stick-slip technique was created to overcome the limitation of the small range of movement that would otherwise result from the maximum extension/retraction of a piezoelectric actuator. Other non-stick-slip stages exist, also incorporating flexure hinge designs. A problem arises if the user wants to have precise nanometer control combined with a large range of movement. If fine control is incorporated into a coarse motion manipulator, then problems will arise due to the above mentioned effects.

It follows that there exists a need for a nano-scale manipulator that provides improved positioning accuracy without suffering the defects of the prior art. It further is desirable that any such manipulator is capable of operating inside the vacuum chamber of a TEM, SEM or similar apparatus.

According to the invention in a first aspect there is provided a nano-scale manipulator comprising a mounting deck and a frame, the deck being moveably secured to the frame by two flexural joints permitting movement of the deck relative to the frame in first and second respective, mutually orthogonal directions of movement; at least one respective, piezoelectric actuator for each of the flexural joints, each respective piezoelectric actuator being secured between the deck and the frame and being extensible and contractible so as to cause movement of the deck in one of the said directions; and a source of electrical power for causing operation of each respective piezoelectric actuator, each of the piezoelectric actuators also being free to flex in directions other than its direction of extension and contraction, wherein each said piezoelectric actuator is elongate and includes secured at each end thereof a respective releasable connector assembly that is relatively stiff in the direction of extension of the piezoelectric actuator and relatively flexible in directions that are perpendicular to the said direction of extension.

Such a manipulator exhibits numerous advantages over the prior art.

First of all, the use of piezoelectric actuators that effectively "bridge" flexural joints provides for an arrangement in which the resistance to motion in the direction of movement caused by the flexural joint is minimal. Therefore the disadvantages of a "stick-slip" type of actuator do not arise.

In effect in the direction of movement the stiffness of each flexural joint is determined by the stiffness of the piezoelectric actuator. As is well known, the extension and contraction of a piezo element take place to the control voltage applied at the ends of the piezo element.

Such extension and contraction can be finely controlled, since it is possible in turn finely to control the applied voltage using an appropriate control circuit. It follows that extremely high positional accuracy may be achieved using a manipulator according to the invention.

The fact that the piezo elements are free to flex in directions other than the particular direction of movement in which they extend and contract means that the stiffness of each flexural joint in directions other than the aforesaid direction of movement is very low. This in turn means that the influence of one of the flexural joints on the motion of another is also minimal. This further improves the accuracy of the device, since there then exists a high degree of proportionality between the voltage applied to a particular piezoelectric actuator and the motion of the manipulator that results.

The relative flexibility of the connector assembly in directions other than the directions of extension and contraction of the actuator advantageously confers on the actuator this ability to flex.

The foregoing features, together with the presence of a releasable clamping member at each end of each piezoelectric actuator, means that each such actuator may be removed and replaced without influencing the other actuators. As explained in more detail below, this is a significant advantage of the invention over the prior art especially when it is necessary to replace or repair an actuator that has failed or become unreliable. In particular the relatively high degree of flexibility of the connectors in directions other than the extension direction of the actuators means that removal and installation of the actuators does not influence the settings of the manipulator in directions other than the extension / contraction direction of the actuator in question.

Conveniently the manipulator additionally includes extending from the frame in a direction parallel to a said direction of movement one or more mounting legs.

Preferably the or each said mounting leg includes formed therein a further flexural joint permitting movement of the deck and frame in a third direction of movement that is mutually perpendicular to the first and second said directions; and the manipulator includes one or more further piezoelectric actuators connected at one end to the frame and connectable at the other end to a further object to which the or each mounting leg is also connectable, the or each further piezoelectric actuator being extensible and contractible so as to cause movement of the deck to the said third direction of movement and the or each further piezoelectric actuator being free to flex in directions other than its extension/contraction direction.

It is further preferable that the adapter member includes a hollow, inner portion having fixedly received therein an end of a said connector element; and a flat, exterior portion that is engageable by a clamping member so as to fix the position of the adapter and hence an end of the connector element.

The foregoing, optional features of the invention provide the connector assembly in a form that permits easy and quick clamping of the connector assembly, and hence a piezoelectric actuator connected to it, in the nano-scale manipulator.

This further helps to solve a significant problem, in the prior art, as set out above and relating to failure of the piezoelectric actuators.

Such failure may arise as a result of shear forces acting on the actuator during movements of the manipulator. The arrangement of the invention in permitting flexing of the piezoelectric actuators in directions other than the directions of extension and contraction tends to minimise the adverse effects of shear forces. Nonetheless the actuators can fail for this or other reasons. In the prior art the ends of the piezoelectric actuators are fixed in the structure of the manipulator, eg. by gluing using a strong adhesive. In such an arrangement it is very difficult as a result to remove a faulty actuator and replace it, without either requiring a time-consuming operation or damaging the manipulator.

The connector assembly of the invention on the other hand provides an arrangement that is readily releasable, through loosening or undoing of the mentioned clamping member, in order to permit the rapid replacement of piezoelectric actuators in the manipulator with little or no risk of damage.

The clamping member may take the form of a clamping screw that is threadedly received in a bore formed in the frame of the manipulator such that on turning of the screw its free end may be caused to protrude beyond the material of the frame for the purpose of engaging the adapter member and releasably clamping it against part of the manipulator so as to secure the piezoelectric actuator in place.

Other forms of clamping member (such as but not limited to cam locking members and spring clips) as would occur to the worker of skill in the art are also within the scope of the invention as claimed.

As is conventional in manipulator technologies (whether of the nano-scale type or not) one may identify the three mutually orthogonal directions of movement of the deck as x-, Y- and Z-directions of movement.

In one preferred embodiment of the invention it is desirable for the piezoelectric actuators that are responsible for causing controlled movement in the X- and Y-directions to include a connector assembly at each end, and to this purpose the invention therefore includes within its scope a nano-scale manipulator as defined herein and including at least one piezoelectric actuator having a said connector assembly secured at each end thereof.

However this arrangement is not they only one that is possible.

In a preferred embodiment of the invention the or each further piezoelectric actuator gives rise to movement of the deck in the Z-direction. It may be desirable for the further piezoelectric actuator(s) to include at at least one end a different type of connector assembly than that specified above.

To this end in another aspect of the invention the nano-scale manipulator may include a said piezoelectric actuator having a said connector assembly secured at one end thereof; and a modified connector assembly secured at the other end thereof, the modified connector assembly including an elongate connector element that is secured at one end to the piezoelectric actuator and at the other end to a modified adapter member.

As indicated, in preferred embodiments of the invention the actuator that includes the modified connector assembly is that responsible for the Z-direction movement; but this need not necessary be so. Indeed any of the actuators of the device may if desired include a modified form of the connector assembly.

Conveniently the modified adapter member, when present, includes a hollow, inner portion having fixedly received therein an end of a said connector element; and a cylindrical, threaded, exterior portion that is threadedly receivable in a threaded bore so as to fix the position of the modified adapter and an end of the connector element.

Such an arrangement is beneficial when seeking to secure (preferably) the Z-direction piezoelectric actuator to the bed of an SEM vacuum chamber, or a similar member, having formed therein one or more threaded bores.

Regardless of the precise design of the connector assembly, preferably the or each said connector element is or includes a filament made from a material selected from:

• Aluminium;

• alloys including Aluminium;

• Titanium;

• Alloys including Titanium; • Polymeric materials.

The connector element may be made, in other embodiments of the invention, from a range of other materials. Aluminium and certain alloys thereof are particularly suitable when the nano-scale manipulator is used in the vacuum chamber of an SEM, because such materials are non-magnetic. Polymeric materials on the other hand may be more suitable when the manipulator is used in an environment that does not include provision for the creation of vacuum conditions. In preferred embodiments of the invention the or each connector element is at one end secured to a said piezoelectric actuator using an adhesive material. In other embodiments of the invention other fixing arrangements may be employed, although adhesive compounds (the compositions of which will be known to the worker of skill) typically are convenient and adaptable when they are being applied.

Preferably the manipulator includes one or more bores formed in the deck and/or the frame, and at least one piezoelectric actuator extends along a said bore.

Such an arrangement makes the manipulator of the invention compact since the piezoelectric actuators then do not lie externally of the frame and deck over any appreciable part of their lengths. However, in alternative arrangements within the scope of the invention the piezoelectric actuators may be arranged to lie on the exterior of the deck / frame combination if desired.

Conveniently the deck and the frame are formed from a common block of material; and each flexural joint includes at least a pair of channels formed in the material of the block so as to define one or more flexible connection leaves interconnecting the deck and the frame.

The channels may conveniently be formed by wire-cutting E. D. M. (electro-discharge machining).

At least one, and preferably each, of the leaves extends, when in the un-flexed condition, perpendicular to the direction of movement, of the deck, that it permits. Thus each flexural joint operates by causing transverse bending of a flexible leaf. The behaviour of the leaf when flexed in this manner is highly predictable, thereby leading to good accuracy of the manipulator.

In an alternative arrangement, however, at least one said leaf may extend, when in the un-flexed condition, at a non-perpendicular angle relative to the direction of movement, of the deck, that it permits.

Combinations of perpendicularly-extending and non-perpendicular leaves are possible in one and the same manipulator according to the invention. Preferably one or more said flexural joints includes at least a pair of channels formed in the block of material so as to define one or more flexible connection leaves interconnecting the deck and the frame.

In practical embodiments of the invention each flexural joint includes three said channels that between them define two said flexible connection leaves. Even more preferably one or more of the flexural joints includes five channels that between them define four said flexible connection leaves, one said channel of each such flexural joint partly defining two of the leaves.

In the case of defining two flexible connection leaves per flexural joint, the motion of the flexural joint may be arranged to resemble that of a kinematic, four-bar chain. This means in turn that the relative movement between the deck and frame in the direction under consideration is rectilinear (as opposed to an arcuate motion, that might otherwise arise from the use of a single flexible connection leaf per flexural joint).

Preferably one or more of the channels, and in practice all of them, includes formed therein one or more through going apertures. These are holes that enable the wire- cutting EDM process to be started from within the outer boundary of a block of material. In particular the apertures may be formed by drilling the material of the deck and frame in a manner that centres the drill bit on the channel, so as to produce approximately semicircular recesses opposite one another in the channel walls defined respectively by the frame and the deck.

Preferably one or more of the said piezoelectric actuators is connected so as to extend and contract in a direction parallel to one of the first and second, mutually orthogonal directions. This arrangement means that the piezoelectric actuator may be arranged to act directly on the deck, giving rise to a simple, direct force-transferring arrangement.

In an alternative embodiment, however, the nano-scale manipulator may include a kinematic path interconnecting the deck and the frame, the kinematic path including a said piezoelectric actuator and a linkage on which the said piezoelectric actuator acts when extending and/or contracting, the linkage transferring force generated in the piezoelectric actuator to cause movement of the deck in a said direction.

In such an embodiment the piezoelectric actuators may be arranged to extend in directions that are not parallel to the directions of movement of the deck for which they are respectively responsible. Such embodiments may be desirable from the standpoint of creating a compact design of the manipulator, and making efficient use of any space available.

Furthermore the use of the kinematic path may advantageously provide for extended "reach" of the manipulator compared with prior art designs. In other words, the kinematic path may be designed so as to provide for more extensive movement of the probe tip, effectively by amplifying (using mechanical components that are linked together) the movement of the piezoelectric actuators.

When as specified above the deck and/or the frame include bores containing the piezoelectric actuators, it is possible to cross-drill the material of the deck / frame and insert through the resulting aperture a clamping member in the form of a fastener (such as a screw, that mates with a thread formed in the cross-bore) that engages the attachment member for the purpose of retaining an end of the piezoelectric actuator in a predetermined location relative to the remainder of the manipulator.

At the opposite end in one preferred form of the invention the piezoelectric actuator protrudes from the bore. The protruding part of the piezoelectric actuator may be surrounded by a hollow canister to which the adjacent attachment member of the piezoelectric actuator is secured. The canister may include one or more flanges that are perforated for the purpose of fixing (eg. screwing) the canister to the frame of the manipulator. Such an arrangement firmly secures one end of the piezoelectric actuator relative to the frame.

The mounting legs as defined above preferably include further flexural joints that permit movement of the deck in a third direction that is mutually orthogonal to the first and second directions defined hereinabove.

As indicated a further piezoelectric actuator is then employed to "bridge" across the flexural joint(s) defined in the one or more mounting legs for the purpose of controlling movement of the deck in the aforesaid, third direction of movement.

In practice the manipulator of the invention would include a plurality of the mounting legs extending parallel to one another. An advantage of this arrangement is that the manipulator may then be stably secured relative to the datum surface (eg. bed) of the SEM / TEM. In a particularly practical arrangement the manipulator includes respective pairs of the mounting legs having extending therebetween a respective further piezoelectric actuator.

Thus in preferred embodiments of the invention a pair of piezoelectric actuators may be employed to provide for movement in the aforesaid third direction of movement. If this third direction is arranged to be the z-(vertical)direction (ie. such that raising of the deck occurs against the action of gravitational forces) the use of a pair of the piezoelectric actuators each disposed between a respective pair of the mounting legs provides adequate force notwithstanding the downwardly acting mass force of the remainder of the manipulator. A control system provided for the purpose of feeding voltages to the piezo elements in order to cause their extension and contracting may be arranged to power the further piezoelectric actuators in synchronism with one another. As a result the deck may be raised and lowered without any change in its orientation occurring.

In an alternative embodiment of the invention it may not be possible or desired to arrange the two piezoelectric actuators of the pair to act in synchronism. In that case if it is desired to avoid uneven raising of the deck caused by uneven extension of the pair of actuators an electronic solution, such as the use of a voltage divider to provide distinct voltages to the two actuators, or separate drivers for the respective actuators, may be employed.

Preferably each further flexural joint includes at least one, and more preferably a pair of channels formed in the material of a said mounting leg so as to define two mounting leg portions that are mutually interconnected by one or more further flexible connection leaves. It is also preferable that the or each further leaf extends, when in the un-flexed condition, perpendicular to the third direction of movement.

Alternatively each further leaf may extend when in the un-flexed condition, in a preferred embodiment of the invention, at a non-perpendicular angle relative to the said third direction of movement.

Combinations of perpendicular and non-perpendicular leaf angles are possible in the case of the further leaves in similar ways to the leaves defined above.

In a particularly preferred embodiment, each further flexural joint includes three said channels that between them define two said flexible connection leaves. Thus the flexural joints defined in the mounting legs are of similar design to those defined between the deck and frame.

In a practical arrangement of the manipulator of the invention the device includes kinematically connected in series therewith a further manipulator permitting controlled movement in at least two mutually skewed directions.

In one optional version of the invention the further manipulator is secured on the deck. In another arrangement the further manipulator may be secured eg. to the datum surface of an SEM / TEM, adjacent the manipulator of the invention.

In the former case it is necessary to effect movement between the manipulator of the invention and the further manipulator, for the purpose of bringing eg. an AFM tip and a target particle into close proximity with one another. To this end the deck may have secured relative to it a tip selected from the list including an AFM tip, a probing wire and/or an electron source base and tip; and the manipulator and/or the further manipulator may include a holder for one or more target articles such as but not limited to nanotubes.

The further manipulator may be of the stick-slip type, or any of a range of other types known in the art.

Regardless of the precise arrangement of the manipulator of the invention and any further manipulator, the deck and frame of the manipulator of the invention preferably are manufactured from non-magnetic materials. Similarly, the or each mounting leg of the manipulator of the invention is manufactured from one or more non-magnetic materials.

The invention is also considered to reside in an SEM including secured within its vacuum chamber and operatively connected to one or more controllers (preferably but not essentially via a vacuum interlock) a nano-scale manipulator as defined herein.

Such an SEM may include one or more joystick controllers connected to a mimic circuit such that movement of the joysticks gives rise to controlled movement, on a very small scale, in the manipulator of the invention. In a further aspect of the invention there is provided an elongate, piezoelectric actuator for use in a nano-scale manipulator and including at at least one end a connector assembly that is relatively stiff in the direction of extension of the piezoelectric actuator and relatively flexible in directions that are perpendicular to the said direction of extension.

Features of such an actuator as described above when considered as part of a nano- scale manipulator are combinable with the features of such an actuator when considered independently and therefore lie within the scope of the invention.

The listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.

There now follows a description of preferred embodiments of the invention, by way of non-limiting example, with reference being made to the accompanying drawings in which:

Figure 1 is a perspective view of a nano-scale manipulator according to the invention; Figure 2 is a plan view, from above, of the Figure 1 device showing its flexural joints and first and second, mutually orthogonal directions of movement;

Figure 3 is a perspective view of a piezoelectric actuator that is incorporated into the Figure 1 device;

Figure 4 is a perspective view of the Figure 1 apparatus, showing mounting legs including flexural joints that give rise to movement in a third direction that is orthogonal to the first and second directions, Figure 4 being partly shown in transparent view in order to illustrate certain constructional details of the device;

Figure 5 is a view similar to Figure 4 in which further parts of the apparatus are shown in transparent form, for the purpose of illustrating further piezoelectric actuators in the device of the invention;

Figure 6 shows the nano-manipulator of the invention incorporated into a module including kinematically in series therewith a further actuator; and

Figure 7 shows in schematic form an SEM or similar microscope incorporating a nano-scale manipulator according to the invention; Figures 8a and 8b show, in schematic form, two possible versions of arrangements of flexure leaves forming part of the invention;

Figure 9 shows another arrangement defining the leaves; Figure 10 shows yet a further way of defining the leaves of a flexural joint forming part of the invention; and

Figures 11a and 11 b illustrate two possible ways, within the scope of the invention, of arranging the piezoelectric actuators so as to define a kinematic (force-transferring) chain of elements.

Referring to the drawings, a nano-scale manipulator 10 according to the invention comprises a mounting deck 11 that is moveably retained inside an essentially surrounding frame 12.

In practice, as described below, frame 12 comprises inner 13 and outer 14 frame sections that each extend around the same three sides of the generally rectangular mounting deck 11.

Deck 11 presents an in-use upwardly facing upper surface that is coplanar with upper surfaces of the inner 13 and outer 14 frame sections. In the preferred embodiment of the manipulator 10 shown, and as described in more detail below, the mounting deck 11 and frame sections 13, 14 are all manufactured from a common block of a non-magnetic metal such as aluminium. If, however an SEM without an immersion lens system is used, the choice of material might be different as would be known to the worker of skill in the art.

The deck 11 is secured to the frame 12 by a plurality of flexural joints 16, 17, 18, 19.

Flexural joints 16, 17 connect the major sides of the essentially rectangular deck 11 to the inner frame section 13, and permit movement of the deck 11 relative to the frame 12 in a first direction labelled "X-direction" in Figure 1.

Flexural joints 18, 19 connect the inner frame section 13, and hence the mounting deck 11 , to the outer frame section 14 so as to permit movement of the inner frame and deck together in a direction, labelled the "Y-direction" in Figure 1 , that is mutually orthogonal to the X-direction.

As best shown in Figure 2, in which the nano-scale manipulator 10 is shown in partly- sectioned view, each of the flexural joints 16, 17, 18, 19 is associated with at least one respective piezoelectric actuator 21 , 22 for effecting controlled movement respectively in the X-direction and the Y-direction. Each piezoelectric element is secured at one end 21a, 22a directly or indirectly to the mounting deck 11 ; and via a second end 21 b, 22b to the outer frame section 14. Since as is well known the application of a controlled voltage across a piezoelectric element causes its contraction and expansion, as desired, it will be apparent that by effecting "bridging" by the piezoelectric elements 21 , 22 between the deck 1 1 and the outer frame portion 14 (in the case of element 21 ) and the inner frame portion 13 and the outer frame portion 14 (in the case of actuator 22) controlled movement of the deck relative to the frame 12 in the X-direction and Y-direction becomes available.

The structure of each piezoelectric actuator 21 , 22 is described in more detail below.

The actuators 21 , 22 in order to achieve accurate motion of the deck respectively in the X-direction and Y-direction are elongate, symmetrical structures the axis of elongation of which in each case is aligned parallel with one of the aforesaid X- and Y-directions of movement.

A source (Figure 7) of electrical power, in the form of an electronic controller in the preferred embodiment shown (although other power sources are possible), is provided for the purpose of effecting controlled contraction and extension of the piezoelectric actuators 21 , 22.

As best illustrated by study of Figures 2 and 3 in combination, each piezoelectric actuator 21 , 22 comprises an elongate, square-section outer casing 24 having secured within it a piezoelectric material.

Each element of piezoelectric material 26 is secured at either end to connector assembly 25 including an elongate connector element in the form of a rod 27 that protrudes externally from one or other end of the casing 24. Each rod 27 is rigidly attached to an adapter member in the form of a clamping plate 28 having formed thereon at least one flat surface 29 that is engageable by a clamping member in a manner described in more detail below.

Each clamping plate 28 is, as illustrated, approximately barrel-shaped and includes a portion at which an end of rod 27 is fixedly received (eg. through use of an adhesive compound, through crimping or in a range of other ways). The clamping plate preferably is unitary in order to make its stiffness as high as possible. At its opposite end each of the rods 27 is secured to the associated piezoelectric actuator for example by gluing.

The overall effect of each connector assembly described herein (whether of the kind identified in relation to Figure 3, or of a modified kind described below) is to fix one end of each connector element (rod 27) so as to take advantage of its stiffness in tension and compression, and its relatively low modulus of elasticity in relation to shear forces.

The connector elements (rods) may be made from any of a range of suitable materials, including those specified herein.

The effect of this arrangement of the piezoelectric actuators is that the stiffness of each actuator in its direction of extension and contraction is controllable in dependence on electrical signals generated in the power source 23; and its stiffness in other directions is generally low. In consequence each piezoelectric actuator influences the stiffness of the nano-scale manipulator 10 essentially in only one direction of movement of the deck 11. This in turn means that operation of either of the piezoelectric actuators 21 , 22 does not couple into movement in any direction other than that of extension and contraction of the associated piezoelectric element 26.

In practice the "bridging" effect of each piezoelectric actuator 21 , 22 is achieved through the formation of respective bores 31 , 32 that are formed in the material of the deck 11 , inner frame section 13 and outer frame section 14 (in the case of piezoelectric actuator 21 ) and the inner frame section and outer frame section 14 (in the case of piezoelectric actuator 22).

The piezoelectric actuators 21 , 22 are inserted into the respective bores from outside the manipulator 10 during assembly thereof, such that in each case a portion of the actuator 21 , 22 protrudes externally of the outer frame section 14 as best illustrated in Figure 2.

The bores 31 , 32 respectively extend parallel to the X- and Y-directions defined herein.

The protruding part of each piezoelectric actuator 21 , 22 is received within a hollow canister 33, 34 that is elongate and at a free end incorporates a secure mounting 36 for a respective clamping plate 28 of the piezoelectric actuator 21 , 22 in question. The flat surface 29 of the clamping plate is employed for the purpose of achieving rigid interconnection between the respective piezoelectric element 21 , 22 and the free end of the associated canister 33, 34.

At each opposite end to its free end each canister 33, 34 terminates in a flange plate 37, 38 that in the embodiment shown extends to either side of the associated canister 33, 34. Each flange plate 37, 38 is perforated such that one or more set screws 39 may pass through it for the purpose of rigidly securing each canister 33, 34 to the exterior of outer frame section 14. In consequence, each piezoelectric actuator 21 , 22 is rigidly secured via one end 21 b, 22b to the exterior of the frame 12.

The opposite ends 21a, 22a of each respective piezoelectric actuator 21 , 22 are, in ways described below, rigidly secured directly or indirectly to the deck 11. It will be apparent therefore that on the application of a voltage to piezoelectric actuator 21 such as to cause contraction of its piezoelectric element 26 the deck 11 will move to the left of Figure 2; and on reduction of the applied voltage relaxation of the piezoelectric element would occur such that it resumes its un-contracted length. This causes movement of the deck 11 to the right in the X-direction as viewed in Figure 2.

The similar application of a voltage to the piezoelectric element 26 of piezoelectric actuator 22 would cause comparable movements of the deck 11 in the Y-direction.

Each of the flexural joints 16, 17, 18, 19 is defined by a series of channels cut or otherwise formed in the material of the block from which the deck 11 and frame 12 are formed.

As best shown in Figure 1 , flexural joint 16 is defined by an L-shaped channel 39 extending inwardly from the side of deck 11 having no part of frame 12 surrounding it; spaced from the L-shaped channel by the material of the block an inner channel 41 defining three "cranked" portions; and spaced from the inner channel 41 by the material of the block a straight channel 42 defining the opposite end of deck 11 to that in which L- shaped channel 39 is formed.

Channel 39 is not necessarily L-shaped in all embodiments of the invention. The reason for the preferred L-shape shown however is to have additional area in deck 11 to enable space for the set-screw 59. Also, deck 11 might in embodiments of the invention be surrounded entirely by the inner part 13 and outer part 14 of frame 12. The result of this arrangement is for the deck 1 1 to be attached to the inner frame section 13 by two flexible, resiliency deformable connection leaves 43, 44 formed of the material of the block.

Each of the leaves 43, 44 extends perpendicular to the X-direction of movement such that on movement of the deck 11 in the X-direction the leaves 43, 44 flex at their ends and/or bend along their lengths so as to confer essentially a parallegram-type action on movement of the deck 11 in the X-direction.

Flexural joint 17 is formed as a mirror image of joint 16, on the opposite side of deck 11 to that on which joint 16 is formed. Straight channel 42 is common to the two flexural joints 16, 17.

Joint 17 therefore defines connection leaves 46, 47 that connect deck 11 to inner frame section 13 on the opposite side to that on which connection leaves 43, 44 lie.

Although in the drawing figures particular shapes of the channels 39, 41 and 42 are illustrated, the scope of the invention embraces numerous other channels designs. As examples one may consider zig-zag channel shapes and sinuous shapes.

Each flexural joint 18, 19 is formed in a broadly similar manner to that of joints 16, 17. Thus joint 19 is defined by a U-shaped channel 48 extending inwardly at an edge of the inner frame section 13 adjacent the un-surrounded end of deck 11 ; a further straight channel 49 extending between in the inner 13 and outer frame sections 14 parallel to the X-direction; and a complex-shape channel 51 extending parallel to the Y-direction between in the inner 13 and outer 14 frame sections at the side of the manipulator 10 that lies remote from the un-surrounded side of deck 11.

The result of this arrangement is to define in flexural joint 19 two further flexible connection leaves 52, 53 that extend perpendicular to the direction of extent of the leaves 43, 44, 46, 47. This arrangement permits parallelogram-type movement of the inner frame sections 13, and hence deck 11 , in the Y-direction relative to outer frame section 14. Since the leaves 52, 53 extend perpendicular to the leaves 43, 44, 46, 47 during such movement of inner frame section 13 in the Y-direction the leaves 43, 44, 46, 47 are placed in tension or compression with no bending moments applied, such that the arrangement during such motion is effectively stiff along the leaves 43, 44, 46, 47. Flexural connection 18 is a mirror image of the connection 19, and for this reason complex-shape channel 51 (that in essence is a straight channel having an n-shaped extension 54 at either end) is common to the two joints 18, 19. In consequence flexural joint 18 defines two further flexible connection leaves 56, 57 that extend parallel to leaves 52, 53 on an opposite side of the nano-scale manipulator 10.

In the same way that motion in the Y-direction of the inner frame section 13 relative to the outer frame section 14 as described above places the connection leaves 43, 44, 46, 47 into straight tension and compression, movement of the deck 11 in the X-direction relative to inner frame section 13 places the connection leaves 52, 53, 56, 57 into straight tension and/or compression such that they experience no bending moments. To all practical purposes therefore the leaves 52, 53, 56, 57 are completely stiff in the X-direction of movement.

In order for the foregoing effects to arise in the flexural joints 16, 17, 18, 19 it is necessary for the various channels defined herein to extend all the way through the block of material from which the deck 11 and frame 12 are formed.

In practice five such channels define the flexural joints 16, 17 giving rise to movement in the X-direction. A further five such channels define the flexural joints 18, 19 that give rise to movement in the Y-direction.

The various channels have formed therein a plurality of recesses 58 which function as wire-cut EDM starting points. In practice these are formed by drilling through the material of the block at locations centred on parts of the various channels illustrated.

As best illustrated in Figure 4, each of the piezoelectric actuators 21 , 22 is secured respectively to the deck 11 and inner frame section 13 by way of a grub screw 59 received in a bore extending through the material of the deck 11 (in the case of actuator 21) and inner frame section 13 (in the case of actuator 22). Each of the bores is threaded such that the grub screws 59 may be screwed into place in order to engage the flat surfaces 29 of the respective ends 21a, 22a of the piezoelectric actuators 21 , 22. In consequence each end of a said actuator that is remote from the associated canister 33, 34 is secured so as to give rise to motion of the deck 11 in the X-direction and Y-direction as required. As is apparent from the figures the lengths of the canisters 33, 34 differ from one another. This is because the piezoelectric actuators 21 , 22 are each of the same length. Actuator 21 however penetrates further into the block than does actuator 22. In consequence more of actuator 22 protrudes beyond the exterior of outer frame section 14 such that a longer canister 34 is required for accommodating the protruding part of actuator 22 than is required in the case of actuator 21.

In alternative arrangements, however, the actuators 21 , 22 may if desired be of uneven lengths (and indeed may differ from one another in other significant respects).

Extending from the in-use underside of the block defining deck 11 and frame 12 are four parallel, elongate mounting legs 61 , 62, 63, 64.

Each leg 61 , 62, 63, 64 is of the same length. The legs terminate in a common plane such that the nano-scale manipulator 10 may be secured to the datum bed 66 or other surface eg. inside the vacuum chamber 67 (Figure 7) of an SEM 68.

Each of the legs 61 , 62, 63, 64 includes formed therein a further flexural joint 69, 71 , 72, 73.

Each of the flexural joints 69, 71 , 72, 73 is formed in a similar manner to the joints 16, 17, 18, 19 by a series of discontinuous channels defining pairs of flexible connection leaves that confer parallel extensile and contractile moveability of the mounting legs 61 , 62, 63, 64 in the Z-direction that is illustrated in Figure 4. As previously explained, the Z-direction is mutually orthogonal to the X-direction and Y-direction defined hereinabove.

Using mounting leg 62 by way of illustration of the structure of the flexural joint 71 , adjacent its lowermost end mounting leg 62 is formed with a straight, horizontally extending channel 74.

A complex-shape channel 76, that is essentially of the same shape as channel 51 , extends upwardly along a major part of the length of mounting leg 62. A further straight channel 77 extends in the in-use horizontal direction adjacent the top of mounting leg 62.

The respective channels 74 and 77 open on opposite sides of the leg 62 and are discontinuous in the sense of not extending all the way from one side of the mounting leg 62 to the opposite side visible in Figure 4. The channels however do extend all the way through the material of the leg 62 in a direction parallel to the foot of the leg, in order to permit flexing as described below.

The result is the definition of a pair 78, 79 of horizontally extending connection leaves that confer a parallegram-type motion in the Z-direction on the extension and contracting of mounting leg 62. The upper leaf 79 defines a flexural connection between the associated leg 71 and the underside of deck 11 , by reason of channel 77 being formed in the region between the material of the leg 71 and the deck 11.

Each of the remaining mounting legs 61 , 63, 64 is designed similarly.

A series of wire-cut EDM starting holes 58 of the same design as those formed in the X- and Y-direction channels is visible in each of the mounting legs 61 , 62, 63, 64.

The overall shape of the mounting deck 11 and frame 12 is essentially rectangular when viewed in plan. As indicated in Figure 4, two of the legs 61, 64 extend downwardly from one end of the resulting rectangle; and the other two legs 62, 63 extend downwardly from the opposite end. These resulting pairs of legs are spaced from one another; and in the spaces between the members of each pair a respective piezoelectric actuator 81 , 82 extends downwardly from the underside of the frame 12.

Each of the actuators 81 , 82 is essentially of the same design as actuators 21 , 22. A pair of the actuators 81 , 82 is however provided so as to permit non-rotational movement of the deck 11 and frame 12 combination in the Z-direction as necessary using one or more of the methods of levelling the deck 11 as described herein. Rotational movement of this combination might otherwise result, were there to be present only a single Z-direction piezoelectric actuator. In certain embodiments of the invention, however, more or fewer Z-direction actuators than the number illustrated may be employed.

At its upper end each actuator 81 , 82 terminates in a clamping plate that while not visible in the drawings is similar to the clamping plate 28 of actuators 21 , 22. Such actuators are secured by way of appropriate fastenings (such as but not limited to grub screws) at the underside of the frame 12. Thus at the upper end each actuator 81 , 82 includes a connector assembly that is similar or identical to the assemblies 25 visible in Figure 3.

At its in-use lower end each actuator 81, 82 includes a modified connector assembly including a modified adapter member formed as a threaded termination 83 that may be screwed into an appropriate, threaded bore formed in the datum surface 66 of an SEM or similar apparatus with which the nano-scale manipulator 10 is intended to be used. In consequence the piezoelectric actuators 81 , 82 are arranged to cause controlled movement in the Z-direction of the mounting deck 11 relative to the datum surface 66. The modified adapter member (threaded termination) 83 includes a portion at which is fixedly received (eg. using an adhesive compound, or in other ways) a connector element in the form of a rod. Although this is not visible in Figure 5 for the avoidance of doubt it may be similar to rod 27 that is visible in Figure 3, or it may be of another type. The adapter member preferably is unitary in order to make its stiffness is as high as possible.

Since the structures of the flexural joints 69, 71 , 72, 73 are in essence similar to those of joints 16, 17, 18, 19 the stiffness of each mounting leg 61 , 62, 63, 64 in the Z-direction is controlled by operation of the piezoelectric actuators 81 , 82. Since these and the legs 61 , 62, 63, 64 themselves are rigidly secured in use to the datum bed 66 flexing of the legs 61 , 62, 63, 64 in directions other than the Z-direction does not occur.

Although in the embodiment shown each flexural joint 69, 71 , 72, 73 is defined by a series of three channels in turn defining flexible connection leaves extending perpendicular to the Z-direction of movement, in other embodiments of the invention other patterns, shapes and arrangements of the channels and connection leaves may be employed. The examples given above in relation to the X- and Y-direction flexural joints may for example be employed in the construction of the mounting legs 61 , 62, 63, 64. Furthermore although in the embodiment shown the legs 61 , 62, 63, 64 are all of the same design this need not necessarily be so; and more or fewer legs than the number shown may be employed. For example, in one embodiment a single mounting leg may be formed including a bore for accommodating a piezoelectric actuator.

In Figure 6 a nano-scale manipulator 10 according to the invention is illustrated having rigidly secured to its deck 11 a holder 84 for eg. a AFM tip 86. Secured on datum bed 66 immediately adjacent manipulator 10 is a further manipulator 87 that may be of the same or a similar type to manipulator 10, or may be of a different design altogether. In the particular embodiment shown in Figure 6, further manipulator 87 is of the "stick-slip" type and has secured on its mounting surface a holder 88 for eg. one or more nanotubes.

Since the motion of stick-slip manipulator such as manipulator 87 is known to be considerably less precise than that of the manipulator 10 of the invention, in the arrangement of Figure 6 the stick-slip manipulator 87 may be employed for coarse positioning of the nanotubes and AFM tip 86 relative to one another. When however the distance between the nanotubes and the AFM tip 86 reaches a predetermined minimum amount operation of the stick-slip manipulator 87 may be terminated, and fine adjustment of the positioning of the AFM tip 86 effected through operation of the nano-scale manipulator 10 in the ways described hereinabove.

Such an arrangement has been found to be highly effective for the purpose of eg. mounting and positioning experiments and similar nano-scale operations.

In other arrangements within the scope of the invention the AFM tip holder 84 could be replaced by another kind of part, or augmented. Examples of alternative holder types could include eg. those designed to support and/or retain etched tungsten wires, AFM cantilever chips or field emission sources.

In alternative embodiments of the invention the positions of the nanotube(s) and AFM tip 86 may be reversed so that the manipulator 10 supports the nanotube(s) and the adjacent manipulator 87 (or, as indicated, another manipulator design) the AFM tip 86 or similar small-scale device.

Figure 7 shows schematically the arrangement by which the nano-scale manipulator 10 of the invention may be employed in the vacuum chamber 67 of an SEM 68.

The manipulators 10, 87 visible in Figure 6 are shown schematically within the vacuum chamber 67 and mounted on a common datum bed 66.

A vacuum interlock 89 of a per se known kind provides an electrical connection between the manipulators 10, 87 and the exterior of the vacuum chamber 66. Respective electronic controllers 23, 91 control the movements of the manipulators 10, 87. The controllers 23, 91 in turn operate under the command of a personal computer 92 or similar processing device. A vacuum gauge or sensor 93 provides feedback on the state of the vacuum in the chamber 67.

As desired the controllers 23, 91 may be operatively connected to joystick controls that, through the use of a per se known mimic software, may be employed for the purpose of precise positioning of the holders 84, 88 relative to one another. In another arrangement in accordance with the invention a coarse manipulator such as a stick-slip type may be mounted on the deck 11 of the nano-scale manipulator 10 of the invention; and in yet a further arrangement a manipulator 10 may be mounted on a mounting deck of a stick-slip or other coarse type of manipulator.

Figure 8 to 11 hereof illustrate, in schematic form, some of the many variants of the arrangements of the invention that are possible.

Figures 8a and 8b illustrate that the deck 11 need not be supported relative to the frame using leaves (such as leaves 43 and 44, which numerals are used in a non-limiting, exemplary sense in Figure 8a) that extend perpendicular (as indicated by the angle ø in Figure 8a) to the direction of movement of deck 11 signified by the arrow head.

On the contrary, as shown in Figure 8b, alternative leaf types 43', 44' may interconnected the deck 11 and frame 12 at non-perpendicular angles ø'. In Figure 8b ø' is approximately 45°, although other angles are possible. The angles that a pair of leaves 43', 44' subtend on opposite sides of the deck 11 when the arrangement is as shown in Figure 8b need not necessarily be the same. Through this possibility it may become viable to design a deck 11 that moves eg. in a non-rectilinear locus if desired.

Figure 9 shows one way of forming leaves such as but not limited to leaves 43 and 44 in a block of the material of frame 12.

In Figure 9 two approximately "U"-shaped channels 94, 96 are formed opposite one another in the block. Extending from the vicinity of one channel 94 to the other 96, and spaced a short distance from the channels 94, 96, is a pair of elongate channels 97, 98. In the vicinity of each channel 94, 96 this arrangement results in thin, flexible, resiliently deformable strips of material defining the leaves.

Figure 10 shows how the leaves 43, 44 may be defined using just two "U"-shaped channels 94, 96. In the Figure 10 arrangement the lateral extremities of these channels lie close to the edges of the block of eg. frame 12. As a result the leaves 43, 44 are defined by the thin, flexible, resiliently deformable strips of material between the lateral extremities of the channels 94, 96 and the adjacent edges of the block. Figure 11a shows in schematic form the arrangement described above, in which a piezoelectric actuator (such as but not limited to actuator 21) is directly coupled to the deck 11 supported by the leaves 43, 44 illustrated.

In this arrangement extension and retraction of the actuator 21 cause movement of the deck 11 in the same direction. This is represented in Figure 11a by the movement arrows pertaining to the actuator 21 and deck 12 extending in the same direction.

Figure 11b shows another arrangement, within the scope of the invention, in which the elements of a kinematic chain are interposed between the actuator 21 and deck 12.

In Figure 11 b the kinematic chain elements chosen are two mutually perpendicular, rigid links 99, 101 that are connected together at a pivot 102.

Actuator 21 acts on link 99 the movement of which causes movement of link 101. The latter being connected to deck 12 supported on leaves 43, 44 is thereby caused to move in a direction perpendicular to the direction of extension and contraction of the actuator 21. This is indicated by the arrows and the angle θ shown in Figure 11 b, although in other arrangements falling within the scope of the invention the kinematic change need not result in a 90° value for the angle θ. Furthermore the kinematic chain may include more elements than the limited number shown.

The variants illustrated are exemplary only. They may be used in combination with one another and/or with the features of the embodiments of the invention described in more detail hereinabove. In particular it is not essential that the direction of extension of the mounting leg actuators 81 , 82 should be parallel to the Z-direction.

Overall the manipulator 10 of the invention solves numerous problems of the prior art associated with accuracy and reliability of nano-scale manipulator arrangements.

Claims

1. A nano-scale manipulator comprising a mounting deck and a frame, the deck being moveably secured to the frame by two flexural joints permitting movement of the deck relative to the frame in first and second respective, mutually orthogonal directions of movement; at least one respective, piezoelectric actuator for each of the flexural joints, each respective piezoelectric actuator being secured between the deck and the frame and being extensible and contractible so as to cause movement of the deck in one of the said directions; and a source of electrical power for causing operation of each respective piezoelectric actuator, each of the piezoelectric actuators also being free to flex in directions other than its direction of extension and contraction, wherein each said piezoelectric actuator is elongate and includes secured at each end thereof a respective releasable connector assembly that is relatively stiff in the direction of extension of the piezoelectric actuator and relatively flexible in directions that are perpendicular to the said direction of extension.

2. A nano-scale manipulator according to any preceding claim including extending from the frame in a direction parallel to a said direction of movement one or more mounting legs.

3. A nano-scale manipulator according to Claim 2 wherein the or each said mounting leg includes formed therein a further flexural joint permitting movement of the deck and frame in a third direction of movement that is mutually perpendicular to the first and second said directions; and the manipulator including one or more further piezoelectric actuators that are connectable between the frame and a further object to which the or each mounting leg is also connectable, the or each further piezoelectric actuator being extensible and contractible so as to cause movement of the deck in a direction parallel to the said third direction of movement and being free to flex in directions other than its direction of extension and contraction.

4. A nano-scale manipulator according to any preceding claim wherein the connector assembly includes an elongate connector element that is secured at one end to the piezoelectric actuator, and at the other end to an adapter member.

5. A nano-scale manipulator according to Claim 4 wherein the adapter member includes a hollow, inner portion having fixedly received therein an end of a said connector element; and a flat, exterior portion that is engageable by a clamping member so as to fix the position of the adapter and hence an end of the connector element.

6. A nano-scale manipulator comprising a mounting deck and a frame, the deck being moveably secured to the frame by two flexural joints permitting movement of the deck relative to the frame in first and second respective, mutually orthogonal directions of movement; at least one respective, piezoelectric actuator for each of the flexural joints, each respective piezoelectric actuator being secured between the deck and the frame and being extensible and contractible so as to cause movement of the deck in one of the said directions; and a source of electrical power for causing operation of each respective piezoelectric actuator, each of the piezoelectric actuators also being free to flex in directions other than its direction of extension and contraction, wherein each said piezoelectric actuator is elongate and includes secured at one end thereof a releasable connector assembly that is relatively stiff in the direction of extension of the piezoelectric actuator and relatively flexible in directions that are perpendicular to the said direction of extension; and a modified connector assembly secured at the other end thereof, the modified connector assembly including an elongate connector element that is secured at one end to the piezoelectric actuator and at the other end to a modified adapter member.

7. A nano-scale manipulator according to Claim 6 wherein the modified adapter member includes a hollow, inner portion having fixedly received therein an end of a said connector element; and a cylindrical, threaded, exterior portion that is threadedly receivable in a threaded bore so as to fix the position of the modified adapter and an end of the connector element.

8. A nano-scale manipulator according to any preceding claim wherein the or each said connector element is or includes a filament made from a material selected from:

• Aluminium;

• alloys including Aluminium; • Titanium;

• Alloys including Titanium;

• Polymeric materials.

9. A nano-scale manipulator according to any preceding claim wherein the or each connector element is at one end secured to a said piezoelectric actuator using an adhesive material.

10. A nano-scale manipulator according to any preceding claim including one or more bores formed in the deck and/or the frame, at least one said piezoelectric actuator extending along a said bore.

11. A nano-scale manipulator according to any preceding claim wherein the deck and the frame are formed from a common block of material; and each flexural joint includes at least one channel formed in the material of the block so as to define one or more flexible connection leaves interconnecting the deck and the frame.

12. A nano-scale manipulator according to Claim 11 wherein at least one said leaf extends, when in the un-flexed condition, perpendicular to the direction of movement of the deck that it permits.

13. A nano-scale manipulator according to Claim 11 wherein at least one said leaf extends, when in the un-flexed condition, at a non-perpendicular angle relative to the direction of movement, of the deck, that it permits.

14. A nano-scale manipulator according to any of Claims 11 to 13 wherein one or more said flexural joint includes at least a pair of channels formed in the block of material so as to define one or more flexible connection leaves interconnecting the deck and the frame.

15. A nano-scale manipulator according to any of Claims 11 to 14 wherein each flexural joint includes three said channels that between them define two said flexible connection leaves.

16. A nano-scale manipulator according to any of Claims 11 to 15 wherein one or more said flexural joint includes five channels that between them define four said flexible connection leaves, one said channel of each such flexural joint partly defining two of the leaves.

17. A nano-scale manipulator according to any preceding claim wherein one or more of the said piezoelectric actuators is connected so as to extend and contract in a direction parallel to one of the first and second, mutually orthogonal directions.

18. A nano-scale manipulator according to any preceding claim including a kinematic path interconnecting the deck and the frame, the kinematic path including a said piezoelectric actuator and a linkage on which the said piezoelectric actuator acts when extending and/or contracting, the linkage transferring force generated in the piezoelectric actuator to cause movement of the deck in a said direction.

19. A nano-scale manipulator according to Claim 2, Claim 3 or any preceding claim depending from Claim 2 or Claim 3 including a plurality of the mounting legs extending parallel to one another.

20. A nano-scale manipulator according to Claim 3 or any preceding claim depending from Claim 3 including respective pairs of the mounting legs having extending therebetween a respective further piezoelectric actuator.

21. A nano-scale manipulator according to Claim 3, Claim 19 or Claim 20 wherein each further flexural joint includes at least one channel formed in the material of a said mounting leg so as to define two mounting leg portions that are mutually interconnected by one or more further flexible connection leaves.

22. A nano-scale manipulator according to Claim 21 wherein the or each further leaf extends, when in the un-flexed condition, perpendicular to the said third direction of movement.

23. A nano-scale manipulator according to Claim 21 wherein each further leaf extends, when in the un-flexed condition, at a non-perpendicular angle relative to the said third direction of movement.

24. A nano-scale manipulator according to any of Claims 21 to 23 wherein each said flexural joint includes at least a pair of channels formed in the leg so as to define one or more flexible connection leaves interconnecting parts of the said leg.

25. A nano-scale manipulator according to Claim 3 or any of Claims 19 to 24 when depending from Claim 3 wherein each flexural joint includes three said channels that between them define two said flexible connection leaves.

26. A nano-scale manipulator according to any preceding claim having kinematically connected in series therewith a further manipulator permitting controlled movement in at least two mutually skewed directions.

27. A nano-scale manipulator according to Claim 26 wherein the further manipulator is secured on the deck.

28. A nano-scale manipulator according to Claim 26 or Claim 27 wherein the further manipulator is of the "stick-slip" type.

29. A nano-scale manipulator according to any preceding claim including secured relative to the deck a tip selected from the list including:

• an atomic force microscopy tip; • a probing wire;

• an electron source base and tip.

30. A nano-scale manipulator according to Claim 29 when dependent from any of Claims 26 to 28 including secured to the manipulator or to the further manipulator one or more nanotubes.

31. A nano-scale manipulator according to any preceding claim, the deck and frame of which are manufactured from non-magnetic materials.

32. A nano-scale manipulator according to Claim 2 or any preceding claim depending therefrom, wherein the or each mounting leg is manufactured from one or more nonmagnetic materials.

33. A scanning electron microscope (SEM) including secured within its vacuum chamber and operatively connected to one or more controllers via a vacuum interlock a nano-scale manipulator according to any preceding claim.

34. An SEM according to Claim 33 including a vacuum interlock via which the nano- scale manipulator is controllable.

35. An elongate, piezoelectric actuator for use in a nano-scale manipulator and including at at least one end a connector assembly that is relatively stiff in the direction of extension of the piezoelectric actuator and relatively flexible in directions that are perpendicular to the said direction of extension.

36. An actuator according to Claim 35 wherein the connector assembly includes an elongate connector element that is secured at one end to the piezoelectric actuator, and at the other end to an adapter member.

37. An actuator according to Claim 36 wherein the adapter member includes a portion having fixedly received thereat an end of a said connector element; and a flat, exterior portion that is engageable by a clamping member so as to fix the position of the adapter and hence an end of the connector element.

38. An actuator according to any of Claims 35 to 37 including at least one piezoelectric actuator having said connector assembly secured at each end thereof.

39. An actuator according to any of Claims 35 to 38 including a said connector assembly secured at one end thereof; and a modified connector assembly secured at the other end thereof, the modified connector assembly including an elongate connector element that is secured at one end to the piezoelectric actuator and at the other end to a modified adapter member.

40. An actuator according to Claim 39 wherein the modified adapter includes a portion having fixedly received thereat an end of a said connector element; and a cylindrical, threaded, exterior portion that is threadedly receivable in a threaded bore so as to fix the position of the modified adapter and an end of the connector element.

41. An actuator according to any of Claims 35 to 40 wherein the or each said connector element is or includes a filament made from a material selected from:

• Aluminium;

• alloys including Aluminium;

• Titanium;

• Alloys including Titanium; • Polymeric materials.

42. An actuator according to any of Claims 35 to 41 wherein the or each connector element is at one end secured to a said piezoelectric actuator using an adhesive material.