Flexible pixel array controlled by conductive shape memory material

An apparatus, method and a computer program are provided. The apparatus includes: an array of pixels, configured to detect radiation, provided on a flexible substrate; a conductive shape memory material coupled to the flexible substrate; and drive circuitry configured to apply a current to the conductive shape memory material in order to change a shape of the conductive shape memory material and the flexible substrate.

TECHNOLOGICAL FIELD

Embodiments of the present invention relate to radiography. In particular, they relate to the detection of X-ray radiation using a bendable apparatus.

BACKGROUND

Radiography has medical and industrial applications. Radiography is used, for example, to examine bones, teeth and organs in a medical context. Radiography is also used as a method of non-destructive testing, for instance, in the automotive industry, the aeronautical industry and the nuclear energy industry.

BRIEF SUMMARY

According to various, but not necessarily all, embodiments of the invention there is provided an apparatus, comprising: an array of pixels, configured to detect radiation, provided on a flexible substrate; a conductive shape memory material coupled to the flexible substrate; and drive circuitry configured to apply a current to the conductive shape memory material in order to change a shape of the conductive shape memory material and the flexible substrate.

According to various, but not necessarily all, embodiments of the invention there is provided a method, comprising: causing a current to be applied to a conductive shape memory material, coupled to a flexible substrate having an array of pixels thereon that are configured to detect radiation, which causes the conductive shape memory material and the flexible substrate to change shape.

According to various, but not necessarily all, embodiments of the invention there is provided computer program instructions that, when performed by at least one processor, cause the above method to be performed.

According to various, but not necessarily all, embodiments of the invention there is provided examples as claimed in the appended claims.

DETAILED DESCRIPTION

Embodiments of the present invention relate detecting radiation using a shape-changing detection apparatus. The apparatus comprises a conductive shape memory material coupled to a flexible substrate. An array of pixels, configured to detect radiation, is provided on the flexible substrate.

The application of a current to the conductive shape memory material by drive circuitry of the apparatus causes a shape of the conductive shape memory material and the flexible substrate to change. The conductive shape memory material may, for example, bend in response to the application of the current, and the coupling between conductive shape memory material and the flexible substrate causes the flexible substrate to bend.

The change in shape of the flexible substrate enables the array of pixels to be positioned closer to an object being imaged, potentially improving image quality and reducing the time required to image non-planar objects. The quantity/dose of radiation that is required for imaging may also be lower.

FIG. 1illustrates a first schematic of an apparatus100. The apparatus100illustrated inFIG. 1comprises drive circuitry20, a substrate22, a pixel array24and a conductive shape memory material26.

The array of pixels24could be a one, two or three dimensional array. If the array24is two dimensional, it may be arranged in perpendicular column and rows. The pixels in the array24are configured to detect radiation, such as electromagnetic (wave) radiation or particle radiation. The pixels may be formed of semiconductor material configured to detect radiation, or one or more other materials configured to detect radiation.

In some embodiments, the pixels in the array24are configured to detect electromagnetic radiation in the form of X-ray radiation. Detection may occur directly or indirectly. In direct detection, X-rays are converted directly into an electric current by the pixels. Such pixels may, for example, be made from alpha selenium or any other appropriate material.

In indirect detection, X-rays are converted into photons which are then, in turn, converted into electric current by the pixels. The X-rays are converted into photons by one or more scintillators. The one or more scintillators may be part of the array of pixels24, or be separate from the array of pixels24. In indirect detection, the pixels in the array24may include any type of photodetector for detecting photons that have been derived from X-rays, including diodes and field-effect transistors.

The array of pixels24is provided on a flexible substrate22. The flexible substrate22may be substantially planar in shape, having a length and width that are each much greater than its thickness/depth. The flexibility of the substrate22may be the same as, or greater than, the flexibility of the array of pixels24. The substrate22could be made from a fabric or a plastic, for instance, such as polyimide (for example, Kapton®), polyethylene naphthalate (PEN) or polyethylene terephthalate (PET).

The conductive shape memory material26is coupled to the flexible substrate22. The conductive shape memory material26is an electrically conductive material that may, for example, be deformable by hand at room temperature.

The conductive shape memory material26has a parent/original shape. The conductive shape memory material26“remembers” its parent shape, such that when the conductive shape memory material26is heated beyond its transition temperature, the shape of the conductive shape memory material26changes from its current shape to its parent shape automatically (that is, without any mechanical assistance). The change in shape that occurs is visible to the naked eye.

The conductive shape memory material26may be a one-way shape memory material or a two-way shape memory material.

When a one-way shape memory material is heated to a temperature above its transition temperature, it changes shape from its current shape to its parent shape. When the material subsequently cools to a temperature below its transition temperature, the material remains in its parent shape (unless mechanically deformed, for example).

A two-way shape memory material remembers two different shapes. It has a high-temperature parent shape, and also a low-temperature parent shape. When a two-way shape memory material is heated to a temperature above a first transition temperature, it changes shape from its current shape to its high-temperature parent shape automatically (that is, without any mechanical assistance). When the material subsequently cools to a temperature below a second transition temperature, the material reverts to its low-temperature parent shape automatically (that is, without any mechanical assistance). The first and second transition temperatures may or may not be the same.

The conductive shape memory material26could, for example, be a conductive shape memory alloy (such as nickel-titanium, copper-aluminum-nickel or copper-zinc-aluminum) or a conductive shape memory polymer.

The drive circuitry20is configured to apply an electric current to the conductive shape memory material26. The application of the electric current to the conductive shape memory material26causes resistive heating. The amount of electric current that is applied by the drive circuitry20is sufficient to cause the conductive shape memory material26to heat to a temperature above its transition temperature, causing the shape of the conductive shape memory material26to change from its current shape to its parent shape.

Due to the coupling between the conductive shape memory material26and the substrate22, the change in shape of the conductive shape memory material26causes the shape of the substrate22to change. The change in shape of the substrate22causes the positioning of at least some of the pixels in the array24, relative to each other, to change.

The parent shape of the conductive shape memory material26may, for example, be a bent/curved shape. If so, when the conductive shape memory material26is heated to a temperature above its transition temperature, the conductive shape memory material26bends, causing the substrate22to bend.

FIG. 2illustrates a flow chart of a first method. In block201ofFIG. 2, the drive circuitry20applies a current to the conductive shape memory material26, which changes shape in block202in the manner described above.

FIG. 3illustrates a second schematic of the apparatus, which includes some additional elements relative toFIG. 1and is given the reference numeral101. The elements having the same reference numerals inFIG. 3as inFIG. 1are the same as those described above in relation toFIG. 1.

The apparatus101illustrated inFIG. 3comprises the drive circuitry20, the substrate22, the array of pixels24and the conductive shape memory material26illustrated inFIG. 1and further comprises at least one processor12, memory14, one or more pressure sensors28, one or more temperature sensors30, readout circuitry32and at least one radiation source34.

The elements20,22,24,26,28,30,32and34are operationally coupled and any number or combination of intervening elements can exist (including no intervening elements).

The drive circuitry20is under the control of the processor12and is configured to apply electric current to the conductive shape memory material26, the pressure sensors28, the temperature sensors30, the readout circuitry32and the radiation source34. The current which is provided to the pressure sensors28, the temperature sensors30, the readout circuitry32and the radiation source34is provided to power those elements. The applied current may be different for each element28,30,32,34, and different from the current applied to the conductive shape memory material26.

The pressure sensors28are configured to provide inputs to the processor12. The pressure sensors28are provided on the substrate22in this example. They may, for instance, be positioned on the same face of the substrate as the array of pixels24.

The pressure sensors28are configured to sense pressure applied by the apparatus101to an object when the conductive shape memory material26changes shape/bends, and provide inputs to the processor12that are indicative of the sensed pressure. The object may, for example, be an object that is being imaged or is to be imaged by the array of pixels24.

The temperature sensors30are configured to provide inputs to the processor12. The temperature sensors30are provided on the substrate22in this example. They may, for instance, be positioned adjacent to one or more portions of the conductive shape memory material26. The temperature sensors30are configured to sense the temperature of the conductive shape memory material26, and provide inputs to the processor12that are indicative of the sensed temperature.

The radiation source34is configured to generate and transmit radiation, some of which may pass through an object before being detected by the array of pixels24. The radiation may be electromagnetic radiation, such as X-ray radiation, or particle radiation.

The readout circuitry32is configured to read information from each pixel in the array of pixels24and to provide that information to the processor12. The processor12is configured to form a one, two or three dimensional image from the information provided by the readout circuitry32.

The processor12is configured to read from and write to the memory14. The processor12may also comprise an output interface via which data and/or commands are output by the processor12and an input interface via which data and/or commands are input to the processor12.

The memory14stores a computer program16comprising computer program instructions (computer program code)18that controls the operation of the apparatus101when loaded into the processor12. The computer program instructions18, of the computer program16, provide the logic and routines that enables the apparatus to perform the method illustrated inFIG. 5. The processor12by reading the memory14is able to load and execute the computer program16.

As illustrated inFIG. 3, the computer program16may arrive at the apparatus101via any suitable delivery mechanism40. The delivery mechanism40may be, for example, a non-transitory computer-readable storage medium, a computer program product, a memory device, a record medium such as a compact disc read-only memory (CD-ROM) or digital versatile disc (DVD). The delivery mechanism40may be a signal configured to reliably transfer the computer program16. The apparatus101may propagate or transmit the computer program16as a computer data signal.

Although the processor12is illustrated as a single component/circuitry it may be implemented as one or more separate components/circuitry some or all of which may be integrated/removable. The processor12may be a single core or multi-core processor.

FIG. 4Aillustrates a front elevation of a first example of the apparatus100/101. Cartesian co-ordinate axes70are also illustrated inFIG. 4Aand other figures, in order to enable the reader to easily orientate one figure with respect to another. InFIG. 4A, orthogonal x, y and z axes are illustrated. Each axis extends in and defines a different, orthogonal dimension. The z-axis extends out of the page inFIG. 4A.

The substrate22illustrated inFIG. 4Ahas a length aligned with the y-axis, a width aligned with the x-axis and a thickness/depth aligned with the z-axis. The substrate is substantially planar in that its length and width are substantially greater than its thickness. In the illustrated example, the length of the substrate22is greater than the width, but this need not necessarily be the case. The length and the width of the substrate22could be substantially the same.

A first edge50of the substrate22is aligned with the length (y) dimension of the substrate22. A second edge51of the substrate22is aligned with the width (x) dimension of the substrate22. A third edge52of the substrate22is aligned with the length (y) dimension of the substrate22and is separated from the first edge50by the width of the substrate22. A fourth edge53of the substrate22is aligned with the width dimension (x) of the substrate22and is separated from the second edge51by the length of the substrate22.

In the example illustrated inFIG. 4A, the array of pixels24is one-dimensional and includes four pixels labelled with the reference numerals24a-24d. More or fewer pixels may be present in other examples.

The apparatus100/101illustrated inFIG. 4Ahas first, second and third elongate portions60,61,62of conductive material. The conductive shape memory material26provides some or all of the elongate portions60,61,62of conductive material. For example, in some implementations, each of the first, second and third elongate portions60,61,62is made from the conductive shape memory material26. In other implementations, the first and third elongate portions60,62are made from the conductive shape memory material26, but the second elongate portion61is made from a different conductive material (for instance, a metal or a conductive polymer), which is not a shape memory material. In such implementations, the second elongate portion61maintains its shape when a current is applied to it which is of a magnitude that would cause the shape of the first and third elongate portions60,62to change.

The first elongate portion60of conductive material extends in the length (y) dimension of the substrate22and is positioned between the first edge50of the substrate22and the array of pixels24(in the x dimension, at least). The second elongate portion61of conductive material extends in the width (x) dimension of the substrate22and is positioned between the second edge51of the substrate22and the array of pixels24(in the y dimension, at least). The third elongate portion62of conductive material extends in the length (y) dimension of the substrate22and is positioned between the third edge52of the substrate22and the array of pixels24(in the x dimension, at least).

In the example illustrated inFIG. 4A, the first, second and third elongate portions60,61,62are positioned on the same face of the substrate22as the array of pixels24.

When current is applied by the drive circuitry20, electrons travel along the first elongate portion60of conductive material to the second elongate portion61of conductive material, and then subsequently to the third elongate portion62of conductive material. Electric current flows in the opposite direction.

FIG. 4Billustrates a front elevation of a second example of the apparatus100/101. The second example illustrated inFIG. 4Bis similar to the first example illustrated inFIG. 4A, but differs in that the array of pixels24is a two-dimensional array rather than a one-dimensional array. The array24illustrated inFIG. 4Bincludes nine pixels labelled with the reference numerals24a-24l. More or fewer pixels may be present in other examples.

BothFIG. 4AandFIG. 4Billustrate the apparatus100/101prior to any current being applied to the conductive shape memory material26and the consequent shape change that ensues.

FIG. 4Crelates to an implementation where the first and third elongate portions60,62are made from conductive shape memory material26, but the second elongate portion61is made from a different conductive material that is not a shape memory material. In the illustrated situation the parent shape of each of the first and third elongate portions60is a curved shape and the drive circuitry20has applied a current to the conductive shape memory material26, causing the first and third elongate portions60,62of conductive shape memory material26to reach the transition temperature and bend into their parent shapes.

Electric current is also applied to the second elongate portion61(since it electrically connects the first and second elongate portions60,62), but the second elongate portion61maintains its shape in response to the application of the current because it is not a shape memory material.

FIG. 4Cillustrates the first and third elongate portions60,62changing shape in the y and z dimensions but not in the x-dimension, which causes the substrate22to change shape in the y and z dimensions but not in the x dimension. In the illustrated example, the extent of the substrate22decreases in the y dimension, increases in the z dimension and remains the same in the x dimension when the first and third elongate portions60,62change shape/bend.

If the conductive shape memory material26is a two-way shape memory material, when the drive circuitry20ceases to apply the current to the first and third elongate portions60,62, the first and third elongate portions60,62will automatically return to the shapes that they had prior to the application of the current.

FIG. 5illustrates a flow chart of a second method which is carried out by the processor12under the control of the computer program code/instructions18. In block501inFIG. 5, the processor12causes the drive circuitry20to apply a current to the conductive shape memory material26of the apparatus100/101. The drive circuitry20applies current to the first, second and third elongate portions60-62, some or all of which are made from conductive shape memory material26.

At block502inFIG. 5, the processor12obtains inputs from the temperature sensors30to determine whether the temperature of the conductive shape memory material26is high enough to cause the conductive shape memory material26to revert to its parent shape. If the temperature is not high enough, the method moves to block503and the processor12controls the drive circuitry20to increase the applied current. The processor12may continuously monitor the temperature via inputs from the temperature sensors30until it determines that the conductive shape memory material26has reached its transition temperature.

In some embodiments, the processor12may learn how the conductive shape memory material26responds to applied current in order to enable the processor12to cause the conductive shape memory material26to change shape more quickly on subsequent occasions.

For instance, in this regard, the processor12may store information in the memory14such as the magnitude of the current that was applied to the conductive shape memory material26when it reached the transition temperature. Additionally or alternatively, the processor12may store information in the memory14regarding the relationship between the increase in applied current over time and associated increase in the temperature of the conductive shape memory material26over time. This information may then be used by the processor12to control the drive circuitry20in a manner that causes the conductive shape memory material26to reach its transition temperature more quickly in future.

At block504, the processor12obtains and interprets inputs from the pressure sensors28. The change in shape of the conductive shape memory material26may cause the apparatus100/101to apply a force to an adjacent object (for example, an object that is being imaged by the array of pixels24). If the inputs from the pressure sensors28indicate that the pressure being applied by the apparatus100/101is above a threshold, the processor12may cause an alert to be provided to a user at block505. Additionally or alternatively, the processor12may cause the drive circuitry20to cease applying current to the conductive shape memory material26.

If the inputs from the pressure detectors20are below a particular threshold (which could be zero or non-zero), the array of pixels24might not be positioned close enough to the object for optimum imaging to occur. In such an instance, the processor12may cause an alert to be provided to a user at block505.

In some embodiments, the processor12may not begin to obtain and interpret inputs from the pressure sensors20until the transition temperature has been reached, because if the transition temperature has not yet been reached the apparatus100/101is not yet exerting pressure on an adjacent object (since a change in shape/bending of the substrate22and the conductive shape memory material26has not yet occurred).

In some circumstances, it might not be necessary for the processor12to obtain and interpret inputs from the pressure sensors20. For example, if an object (or objects) of a given shape are to be imaged on multiple occasions by the apparatus100/101, once the processor12has determined that application of a current of a particular magnitude to the conductive shape memory material26does not cause the pressure sensors28to indicate that the pressure being applied by the apparatus100/101is above a threshold, it may not be necessary for the processor12to go through the process of obtaining and interpreting inputs from the pressure sensors20on subsequent occasions when that/those object(s) is/are being imaged.

At block506inFIG. 5, the processor12controls the radiation source34to initiate radiation output. Radiation is output in the direction of the array of pixels24.

At block507inFIG. 5, the processor12controls the readout circuitry32to read the pixels in the array24(while the conductive shape memory material26is in its parent shape) and provide the readout information to the processor12. The processor12may then construct an image based on the readout information and, in some embodiments, control a display to display the image.

At block508inFIG. 5, the processor12controls the radiation source34to cease outputting radiation and, at block509inFIG. 5, the processor12causes the application of current to the conductive shape memory material26to cease.

FIG. 6Aillustrates a front elevation of a third example of the apparatus100/101.FIG. 6Billustrates a rear elevation of a third example of the apparatus100/101. The third example of the apparatus100/101is similar to the second example illustrated inFIG. 4B, but differs in that the first, second and third elongate portions60-62are not located60,61,62on the same face of the substrate22as the array of pixels24.

In the third example illustrated inFIGS. 6A and 6B, the array of pixels24is located on a first face of the substrate22defined by the length (y) and width (x) dimensions of the substrate22, and the first, second and third elongate portions60-62of conductive material are located on a second face of the substrate22defined by the length (y) and width (x) dimensions of the substrate22. The first and second faces are separated in the depth (z) dimension by the thickness of the substrate22.

In the first and second examples of the apparatus100/101illustrated inFIGS. 4A and 4B, the first and third elongate portions60,62of conductive material are separated from the array of pixels24in the width (x) dimension. The second elongate portion61of conductive material is separated from the array of pixels24in the length (y) dimension. This prevents the first, second and third elongate portions60-62of conductive material from being imaged by the array of pixels24.

In the third example, however, since the first, second and third elongate portions60-62of conductive material are positioned behind the array of pixels24, there is no risk of them being imaged and, therefore, such separation is not required.

FIG. 7illustrates a front elevation of a fourth example of the apparatus100/101in which the first, second and third elongate portions60-62of conductive material are coupled to the substrate22by a plurality of grips71.

The grips71may, for example, be U-shaped grips which bind the first, second and third elongate portions60-62to a face of the substrate22, which may or may not be the same face as that on which the array of pixels24is provided.

The grips71bind/couple the first and third elongate portions60,62of conductive material to the substrate22at various binding positions along the length (y) dimension.

Each binding position is separated in the length (y) dimension from one or two adjacent binding positions. The first and third elongate portions60,62of conductive material are uncoupled/unbound to the substrate22between the binding positions, providing them with freedom to change shape.

It can be seen inFIG. 7that there are a series of regions between adjacent binding positions that is aligned with pixels in the width (x) dimension. For example, the pixels labeled with the reference numerals24a,24eand24iinFIG. 7are aligned with a region between two binding positions at which the first elongate portion60of conductive material is bound to the substrate22, and aligned with a region between two binding positions at which the third elongate portion62of conductive material is bound to the substrate22.

Other aspects of the fourth example of the apparatus100/101may be the same as in the other examples described above.

FIG. 8Aillustrates a front elevation of a fifth example of the apparatus100/101. The fifth example of the apparatus100/101is similar to the fourth example of the apparatus100/101in that the first and third elongate portions60,62of conductive material are made from conductive shape memory material26and the second elongate portion61of conductive material is made from a different conductive material that is not a shape memory material.

In the fifth example of the apparatus100/101, the first and third elongate portions60,62of conductive material are bound/coupled to the substrate22by threading them through the substrate22to couple them to the substrate.

The fifth example of the apparatus100/101is similar to the fourth example in that the first and third elongate portions60,62of conductive material are bound to the substrate22at various binding positions along the length (y) dimension. Each binding position is separated in the length (y) dimension from one or two adjacent binding positions. The first and third elongate portions60,62of conductive material are uncoupled/unbound to the substrate22between the binding positions, providing them with freedom to change shape.

As inFIG. 7, it can be seen inFIG. 8Athat there are a series of regions between adjacent binding positions that is aligned with pixels in the width (x) dimension. For example, the pixels labeled with the reference numerals24a,24eand24iinFIG. 8Aare aligned with a region between two binding positions at which the first elongate portion60of conductive material is bound to the substrate22, and aligned with a region between two binding positions at which the third elongate portion62of conductive material is bound to the substrate22.

FIG. 8Billustrates a side elevation of a binding/coupling position where the first elongate portion60of conductive material is threaded through the substrate22. At the various binding positions along the length of the substrate22, between the first edge50and the array of pixels24, the first elongate portion60of conductive material enters a first aperture73followed by a second aperture74, causing a portion23of the substrate22to be located above the first elongate portion60of conductive material at those binding positions. The apertures73,74may, for example, be perforations in the substrate22.

FIG. 9illustrates a front elevation of a sixth example of the apparatus100/101. In the illustrated example, the apparatus100/101has a one dimensional array of pixels24, but this need not necessarily be the case. The sixth example of the apparatus100/101is similar to the fifth example illustrated inFIGS. 8A and 8Bin that the first and third elongate portions60,62of conductive material are coupled/bound to the substrate22by threading them through the substrate22.

The sixth example of the apparatus100/101illustrated inFIG. 9differs from the fifth example illustrated inFIGS. 8A and 8Bin that the first and second elongate portions60,62of conductive material include some linear regions63aand some springs63b.

In some implementations, both the linear regions63aand the springs63bare made from conductive shape memory material26. In other implementations, the linear regions63aare made from a different conductive material, which is not a shape memory material, and merely the springs63bare made from conductive shape memory material26.

The presence of the springs63bmay enable the first and third elongate portions60,62and the substrate22to change shape to a greater extent than is the case in the fifth example illustrated inFIG. 8A. In some implementations, the first elongate portion60of conductive material is symmetric with the third elongate portion62of conductive material about an axis of symmetry that is aligned with the length (y) dimension. In other implementations, such as that illustrated inFIG. 9, no such symmetry exists. The composition of the first and third elongate portions60,62in relation to the presence of linear regions63aand springs63bwill depend upon the desired implementation and the desired shape change.

In the example illustrated inFIG. 9, the second elongate portion61of conductive material is made from a conductive material that is not a shape memory material, but this need not necessarily be the case.

FIG. 10illustrates a seventh example of the apparatus100/101. The seventh example of the apparatus100/101is similar to the fifth example of the apparatus100/101illustrated inFIGS. 8A and 8B, except that it further comprises a plurality of stiffeners64which stiffen the apparatus100/101in various regions to prevent the substrate22from bending/changing shape in regions where the pixels24a-24lare located. In this regard, the stiffeners64may be aligned with the position of the pixels24a-24lin the width (x) and length (y) dimensions. In the illustrated example, the substrate22is positioned between the pixels24a-24land the stiffeners64but in other implementations, the stiffeners64could be positioned between the pixels24a-24land the substrate22.

FIG. 11illustrates an eighth example of the apparatus100/101which is effectively a combination of the seventh example of the apparatus100/101illustrated inFIG. 9and the eighth example of the apparatus100/101illustrated inFIG. 10. In this regard, the eighth example of the apparatus100/101illustrated inFIG. 11comprises first and third elongate portions60,61of conductive material that each include linear regions63aand springs63band in that it includes a plurality of stiffeners64as described above in relation toFIG. 10.

As used in this application, the term ‘circuitry’ refers to all of the following:

(b) to combinations of circuits and software (and/or firmware), such as (as applicable):

(i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions and

(c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. For example, it will be appreciated by those skilled in the art that embodiments of the invention are not limited to apparatus100/101which bend in the directions discussed above and illustrated in the figures.

In the description above, the first, second and third elongate portions60-62of conductive material are described as being part of the same circuit, such that when current is applied by the drive circuitry20, electrons travel along the first elongate portion60of conductive material to the second elongate portion61of conductive material, and then subsequently to the third elongate portion62of conductive material.

Alternatively, in each of the examples of the apparatus100/101described above, any or all of the first, second and third elongate portions60-62of conductive material could be connected separately to the drive circuitry20(that is, each elongate portion60-62is not electrically connected to one or both of the other elongate portions60-62), such that the drive circuitry20can apply current to them separately under the control of the processor12. This enables one elongate portion60-62to undergo a shape change separately from the others, enabling a wider variety of shapes to be formed than if the first, second and third elongate portions60-62are electrically connected and controlled collectively.

Also, while the conductive shape memory material26is described as being elongate in shape in the examples described above, that need not be the case in every implementation.