US20070079911A1

US20070079911A1 - Method for erasing stored data and restoring data

Info

Publication number: US20070079911A1
Application number: US11/249,171
Authority: US
Inventors: Alan Browne
Original assignee: Browne Alan L
Current assignee: GM Global Technology Operations LLC
Priority date: 2005-10-12
Filing date: 2005-10-12
Publication date: 2007-04-12

Abstract

A method for selectively erasing information from or restoring information to a shape memory material includes selectively heating and/or selectively cooling, to a predetermined temperature and for a predetermined time, at least a portion of at least one heating element or cooling element adjacent a predetermined area of the shape memory material, thereby erasing the information stored therein or restoring information thereto. The heating element or cooling element is located in an array of heating or cooling elements.

Description

TECHNICAL FIELD

The present disclosure relates generally to stored data, and more particularly to methods for erasing stored data and for restoring data.

BACKGROUND

Shape memory materials (SMM) have been applied to a wide variety of applications, in part, because of their ability to undergo a reversible phase transformation. Shape memory materials include shape memory alloys (SMA) and shape memory polymers (SMP).
It has been shown that the thermally induced martensite to austenite transformation of plastically indented SMA allows for indent recovery on the microscale and nanoscale. It has also been shown that the thermally induced glass transition temperature transformation of SMP that was indented in its low modulus high temperature state allows for indent recovery on the microscale and nanoscale. When SMA or SMP (formed as a sheet, film, block, or the like) is used as an information storage medium, erasing information stored in the form of plastically deformed features of surface topography generally desirably involves relatively fast heating and cooling, so that the temperature of the indents moves above and below the martensite to austenite transformation temperature or the glass transition temperature transformation, respectively.
Shape memory materials may also have information stored at high temperatures in its memorized form. The SMM may be flattened in the martensite phase (SMA) or in the high temperature phase followed by cooling while applying a flattening load (SMP). Heating followed by cooling results in the global restoration of the memorized, indented shape.
However, bulk heating and cooling methods currently employed for SMM information storage generally do not achieve desirable temporal or spatial selectivity. Such heating and cooling methods also generally do not allow for quick, localized removal of stored information or restoration of previously stored information from specific areas.
As such, it would be desirable to provide method(s) for erasing stored information from and/or restoring information to a localized area of a shape memory material.

SUMMARY

The present disclosure substantially solves at least some of the problems and/or drawbacks described above by providing a method for selectively erasing information from and/or selectively restoring information to a shape memory material. The method includes selectively heating and/or selectively cooling, to a predetermined temperature and for a predetermined time, at least a portion of at least one heating element or cooling element, which is positioned in an array of heating or cooling elements, adjacent a predetermined area of the shape memory material, thereby erasing the information stored therein or restoring information thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though not necessarily identical components. For the sake of brevity, reference numerals or features having a previously described function may not necessarily be described in connection with other drawings in which they appear.
FIG. 1 is an exploded, semi-schematic perspective view of an embodiment of an array of heating/cooling elements in contact with a shape memory material;
FIG. 2 is a schematic view of an embodiment of an array of heating/cooling elements with no heating/cooling elements heated/cooled;
FIG. 3 is a schematic view of an embodiment of the array of heating/cooling elements shown in FIG. 2 with one heating/cooling element heated/cooled;
FIG. 4 is a schematic view of an embodiment of the array of heating/cooling elements shown in FIG. 2 with a junction heated/cooled;
FIG. 5 is a schematic view of an embodiment of the array of heating/cooling elements shown in FIG. 2 with a portion of the array heated/cooled;
FIG. 6 is a schematic view of an embodiment of the array of heating/cooling elements shown in FIG. 2 with two discrete portions of the array heated/cooled;
FIG. 7 is a schematic view of an alternate embodiment of an array of heating/cooling elements having discrete junctions heated/cooled; and
FIG. 8 is an exploded, semi-schematic perspective view of an embodiment of an array of heating/cooling elements in contact with a shape memory material having varying thicknesses and compositions.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Shape memory materials have been used to store information. Generally there are a variety of shape memory materials and methods corresponding to the material for storing, erasing, and/or restoring information. Non-limitative examples of the shape memory materials include shape memory alloys (SMA), shape memory polymers (SMP), combinations thereof, combinations thereof mixed with non shape memory materials, or other shape memory materials that return to a memorized original state once the material is heated to a predetermined temperature. It is to be understood that the predetermined temperature may vary, depending, at least in part, on the shape memory material used, the composition of the material used, and combinations thereof.
Shape memory alloys (SMAs) typically exist in several different temperature-dependent phases. A non-limitative example of these phases include the martensite and austenite phases. Generally, and as used herein, the martensite phase refers to the more deformable (lower modulus), lower temperature phase, whereas the austenite phase refers to the more rigid, higher temperature phase.
When the SMA is in the martensite phase and is heated, it begins to change into the austenite phase. When the SMA is in the austenite phase and is cooled, it begins to change into the martensite phase. It is to be understood that the stiffness (elastic modulus) of shape memory alloys may be significantly greater (2.5 to 3 times for common SMAs) in their austenite phase as compared to that in their martensite phase.
Examples of suitable shape memory alloy materials include, but are not limited to copper based alloys (non-limitative examples of which include copper-zinc alloys, copper-aluminum alloys, copper-gold alloys, and copper-tin alloys), gold-cadmium based alloys, indium-titanium based alloys, indium-cadmium based alloys, iron-platinum based alloys, iron-platinum based alloys, iron-palladium based alloys, manganese-copper based alloys, nickel-titanium based alloys, nickel-aluminum based alloys, nickel-gallium based alloys, silver-cadmium based alloys, and/or the like, and/or combinations thereof. It is to be understood that the alloys may be binary, ternary, or any higher order so long as the alloy composition exhibits a shape memory effect, e.g., change in shape orientation, damping capacity, and the like.
Generally, the memorized shape of the SMA may be flat or may have information stored therein in the form of surface features, such as, for example, indents or bumps. In an embodiment, the memorized shape of the SMA is substantially flat. In this embodiment, information may be plastically indented in the SMA when it is in its cooler martensite phase. The deformed material may then be heated above its austenite transformation temperature, thereby returning it to its original structure (i.e. an undeformed state).
In another embodiment, the memorized shape of the SMA has information stored therein. In this embodiment, the SMA may be flattened when it is in its cooler martensite phase. The flattened material may then be heated above its austenite transformation temperature, thereby returning it to its original structure (i.e. a deformed/indented state).
Shape memory polymers (SMP) are co-polymers including at least two different segments, each segment contributing differently to the elastic modulus properties and thermal transition temperatures of the material. The term “segment,” as used herein, refers to a block, graft, or sequence of the same or similar monomers or oligomers, which are copolymerized to form a substantially continuous, crosslinked network of these segments. The segments may be crystalline or amorphous materials and may be “hard” segment(s) or “soft” segment(s), where the hard segment generally has a higher glass transition temperature (Tg) or melting point than the soft segment. The segments contribute to the overall flexural modulus properties of the SMP and the thermal transitions thereof.
Shape memory polymers may include thermoplastic materials, thermoset materials, interpenetrating networks, semi-interpenetrating networks, and/or mixed networks, and/or combinations thereof. The polymers may be a single polymer or a blend of polymers. The polymers may be linear or branched thermoplastic elastomers with side chains or dendritic structural elements. Suitable polymer components to form an SMP include, but are not limited to, polyphosphazenes, poly(vinyl alcohols), polyamides, polyester amides, poly(amino acids), polyanhydrides, polycarbonates, polyacrylates (non-limitative examples of which include poly(methyl methacrylate), poly(ethyl methacrylate), poly(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate) and poly(octadecyl acrylate)), polyalkylenes, polyacrylamides, polyalkylene glycols, polyalkylene oxides, polyalkylene terephthalates, polyorthoesters, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyesters, polylactides, polyglycolides, polysiloxanes, polyurethanes, polyethers, polyether amides, polyether esters, polystyrene, polypropylene, polyvinyl phenol, polyvinylpyrrolidone, chlorinated polybutylene, poly(octadecyl vinyl ether) ethylene vinyl acetate, polyethylene, poly(ethylene oxide)-poly(ethylene terephthalate), polyethylene/nylon (graft copolymer), polycaprolactones-polyamide (block copolymer), poly(caprolactone) dimethacrylate-n-butyl acrylate, poly(norbornyl-polyhedral oligomeric silsesquioxane), polyvinyl chloride, urethane/butadiene copolymers, polyurethane block copolymers, styrene-butadiene-styrene block copolymers, and/or the like, and/or combinations thereof.
The memorized shape of an SMP may be set by melting or processing the polymer at a temperature higher than the highest thermal transition temperature for the SMP or its melting point, followed by cooling below that thermal transition temperature. In an embodiment, the temperature to set the memorized shape ranges from about 100° C. to about 300° C. A temporary shape may be set by heating the material to a temperature higher than any Tg of the SMP, but lower than the highest Tg or its melting point; applying an external stress or load while processing the material; and by cooling, with the load remaining applied, to fix the shape. The SMP may revert to its memorized shape by heating the material (with the stress/load removed) above its Tg and below the highest thermal transition temperature.
Generally, the memorized shape of the SMP may be flat or may have information stored therein. In an embodiment, the memorized shape of the SMP is substantially flat. In this embodiment, information may be recorded in the SMP as a temporary shape by first indenting the SMP while it is above the Tg of its low temperature phase, and then cooling the SMP with the indenting load still applied, as previously described. The deformed material may then be heated above its Tg and below the highest thermal transition temperature with the indenting load removed, thereby returning it to its original structure (i.e. an undeformed state).
In another embodiment, the memorized shape of the SMP has information stored therein. In this embodiment, the SMP may be flattened as a temporary shape, as previously described. The flattened material may then be heated above its Tg and below the highest thermal transition temperature, thereby returning it to its original structure (i.e. a deformed/indented state).
Shape memory materials may also be established on (e.g. laminated on) elastic substrates. It is to be understood that power on-hold and power on-deletion techniques may be used with such substrates for erasing and restoring information in the SMM or elastic substrate. Generally, the elastic substrate has a modulus between either those of the martensite and austenite phases of an SMA or between the low and the high temperature states of an SMP.
In a non-limitative example of the power on-hold technique, an SMA has an indented memorized shape and is established on an elastic substrate. In this example, the SMA is flattened through plastic deformation of the indentations while in the lower temperature martensite state. The elastic substrate and the SMA may be bonded, and in the martensite phase, the shape memory material and the substrate are both in a first, non-indented, state. Heating of the SMA causes the indented memorized state to be restored, thereby deforming the elastic substrate. It is to be understood that the SMA may hold the indentation(s) as long as heat is applied. Once the heat is removed, both materials cool and the elastic substrate tends to pull the SMA back to a non-indented state.
In a non-limitative example of the power deletion technique, an SMP has an indented memorized shape and is established on a similarly elastically indented originally flat elastic substrate. In this example, when heat is applied, the SMP relaxes to the unstressed (non-indented) shape of the elastic substrate. It is to be understood that the relaxed shape will remain as long as heat is applied. It is to be further understood that the SMP may be indented during heating, and that rapid cooling during the indent may be used to lock the information into the SMP, and thus into the elastic substrate to which it is bonded.
In a non-limitative example of the power on-deletion technique, an SMA has a flat memorized shape. The SMA may be laminated on an elastic substrate that has an indented surface geometry, so that the SMA takes on the indented shape. When heat is applied, the shape memory effect in the SMA flattens its surface and flattens the indent pattern in the elastic substrate. It is to be understood that the SMA and the substrate hold this shape until heat is removed. Upon removal of the heat, the elastic substrate reverts to its original indented shape, and the dents are re-introduced in the SMA.
Embodiments of the methods disclosed herein advantageously allow the selective erasure of data stored in a shape memory material or the selective restoration of previously stored information in the shape memory material. Particular areas of the shape memory material(s) may be exposed to temperatures above or below its transition temperature. In an embodiment, such selective heating and/or cooling may facilitate the erasure of information from those specific areas of the shape memory material, without erasing the entire surface. In another embodiment, such selective heating and/or cooling facilitates the restoration of information from those specific areas of the shape memory material, without restoring information to the entire surface.
Referring now to FIG. 1, an embodiment of a shape memory material 10 is established on a substrate 12. The shape memory material 10 may be established on all or a portion of the substrate 12. It is to be understood that the array of heating/cooling elements 14 may be incorporated into the shape memory material 10 (as shown in this figure), or into the substrate 12 upon which the material 10 is established, or may be a separate component capable of being positioned adjacent the material 10. Generally, it is to be understood that the heating/cooling elements 14 are to be in thermal communication with the material 10 when erasure or restoration is desired. It is to be further understood that area(s) of the shape memory material 10 adjacent the heating/cooling element(s) 14 are consequently heated or cooled when the temperature of the heating/cooling element(s) 14 is changed.
In an embodiment, any suitable substrate 12 may be selected. One non-limitative example of a substrate material is a sheet of low or non-thermal conductivity material. It is to be understood that a low or non-thermal conductivity material substantially isolates the heating or cooling to areas of the SMM that are adjacent the heated or cooled element(s) 14. Another non-limitative example of a substrate material is the previously described elastic materials.
In an embodiment of the method, the predetermined areas of the shape memory material 10 are subjected to heating or cooling from an array of individual heating/cooling elements 14 that are in thermal communication with the material 10. It is to be understood that the heating/cooling elements 14 are adapted to be individually heated or cooled, so that one, a portion of one, and/or a group of elements 14 may be heated or cooled. Non-limitative examples of the heating/cooling elements 14 include wires, nanotubes (a non-limitative example of which includes carbon nanotubes), fluid channels (a non-limitative example of which may also include connected pores), conductive fibers, lasers, or the like, or combinations thereof. It is to be understood that the elements 14 may also be established in a stylus.
The following non-limitative embodiment(s) may be incorporated into and/or on a substrate 12 onto which the shape memory material 10 is established. As previously stated and as shown in FIG. 1, the elements 14 may also be established in the shape memory material 10 (an example of which includes an SMP).
In a non-limitative embodiment in which the elements 14 are nanotubes, channels, or interconnected pores, selective heating or cooling may be accomplished by directing heated or cooled fluid (e.g. liquids, gases, or mixtures thereof) through at least a portion of the nanotube(s), channels, or a flow path created by interconnected pores that is adjacent the area of the shape memory material 10 where information erasure or restoration is desirable. In another non-limitative embodiment in which the elements 14 are nanotubes or conductive fibers, selective heating or cooling may be accomplished by resistively heating or cooling at least a portion of the nanotube(s) or conductive fibers that is adjacent the area of the shape memory material 10 where information erasure or restoration is desirable.
In still another non-limitative embodiment in which the elements 14 are wires, selective heating or cooling may be accomplished by resistively heating or cooling at least a portion of the wire adjacent the area of the shape memory material 10 where information erasure or restoration is desirable.
Referring now to FIG. 2, an embodiment of an array 100 of heating/cooling elements 14 is disclosed. As previously described, the array 100 may be established in a substrate 12, on a substrate 12, in the SMM 10, or in some other element used to heat or cool predetermined areas of a shape memory material 10. It is to be understood that each heating/cooling element 14 may be selectively activated to heat or cool specific areas of the material 10 to a predetermined temperature.
The elements 14 shown in FIG. 2 are crossed at approximately 90°, thereby forming a junction/node 16 at each cross section. In this embodiment, the elements 14 may be crossed at any non-zero angle to form the junction 16. It is to be understood that the individual element(s) 14 (or portions thereof) may be heated or cooled to a temperature suitable for erasing information from the shape memory material 10 or for restoring information to the shape memory material 10. Alternately, it is to be understood that at predetermined junction(s) 16, a combined temperature of the elements 14 may be suitable for delivering a sufficient amount of heat locally to erase information from the shape memory material 10 or to restore information to the shape memory material 10.
It is to be understood that the entire element 14 may be heated/cooled in order to supply heat/cooling to the junction 16. As such, heating or cooling may be controlled so that the predetermined temperature is not achieved at other areas adjacent the heated/cooled element 14. For example, two crossing elements 14 may be heated so the combined amount of heat delivered by the two crossing elements 14 at the junction/node 16 is enough to raise the temperature at the junction 16 sufficiently to erase or restore information at the junction 16. In this example, once the information is erased or restored, the elements 14 are no longer heated so that the temperature of the individual elements 14 (other than at the desired junction 16) does not reach the predetermined temperature.
FIGS. 3 through 7 depict various patterns in which the heating/cooling elements 14 of the array 100 shown in FIG. 2 may be heated/cooled to selectively erase or restore information from or to the shape memory material 10. In the embodiment shown in FIG. 3, a single element 14 is heated or cooled along substantially its entire length. This embodiment of the element 14 may erase or restore a single line of information from or to the adjacent heated portion of the shape memory material 10. It is to be understood that when the material 10 reaches its transformation temperature, the information stored along that line will be substantially erased or information previously erased along that line will be substantially restored. It is to be further understood that the temperature of the element 14 may be adjusted so that the material 10 along the line is heated or cooled to its transformation temperature within a desirable time frame.
As depicted in FIG. 4, two crossed elements 14 in the array 100 are activated along their entire length, substantially their entire length, or at a junction 16 where they cross. Approximately 50% (or any other suitable ratio, e.g. 70/30, 40/60, etc.) of the heat/cooling may be supplied by each element 14. As such, heat/cooling and the resulting temperature delivered along each element 14 alone may not be sufficient for erasing the stored data or restoring erased data, however, the combined heat or cooling delivered at the junction 16 where the two elements 14 cross will provide the temperature required for the material 10 (at the junction 16) to reach its transformation temperature. Therefore, in an embodiment, information stored at the junction 16 is erased, leaving the information stored in the rest of the surface intact. In another embodiment, previously erased information at the junction 16 is restored, leaving the information previously erased from the rest of the surface gone. The area of erasure or restoration may be controlled through temporal control of the elements 14. It is to be understood that temperature, time, proximity of the element(s) 14, heat transfer coefficient between the element 14 and the SMM 10, and/or the like may be optimized for the particular erasure or restoration system.
FIGS. 5 and 6 depict still other embodiments of the array 100 used for selectively erasing or restoring information. In the embodiment shown in FIG. 5, predetermined portions of various elements 14 in the array 100 are selectively heated or cooled. As such, information stored at a discrete area of the shape memory material 10 adjacent the heated or cooled area of the array 100 may be erased or restored. FIG. 6 is similar to FIG. 5 in that predetermined portions of various elements 14 are heated or cooled. FIG. 6 further depicts multiple discrete areas of the array 100 heated or cooled to substantially simultaneously erase or restore information adjacent the heated or cooled areas.
FIG. 7 illustrates an alternate embodiment of the array 100 used in an embodiment of the disclosed method. Any number of heating/cooling elements 14 in the array 100 may be crossed at any angle relative to any other number of elements 14. FIG. 7 shows an array 100 having elements 14 crossing at about 90° and other elements 14 crossing at about 45°. In this embodiment, at certain points in the array 100, three elements 14 cross each other. It is to be understood that at a junction 16 where the elements 14 cross, each of the three crossing elements 14 may be activated to supply approximately 33% (or any other suitable ratio summing to about 100%) of the heat flux to reach the transformation temperature of the material 10. As such, the combined heat/cooling from multiple elements 14 may erase or restore the information adjacent the heated/cooled area. It is to be understood however, that one or more individual elements 14 in the array 100 may also be heated or cooled to the desired temperature to erase or restore information adjacent the heated or cooled area. Still further, discrete areas (as opposed to the junctions 16 shown in FIG. 7) may be heated/cooled as previously described.
Referring now to FIG. 8, an additional embodiment of the shape memory material 10 on a substrate 12 is depicted. It is to be understood that changes in material 10 thickness or composition may change the temperature distribution in the material 10, thereby changing the parameters for erasing or restoring. By adjusting the shape memory material 10 thickness or composition, specific areas of the material 10 may be susceptible to lower temperatures, while other areas may be susceptible to higher temperatures for the same amount of heat/cooling delivered. For example, information at thinner sections of the material 10 may be erased or restored more quickly than information at thicker sections.
As mentioned earlier, different shape memory material compositions may have different transformation temperatures. Therefore, combinations of different material compositions in one device allow the user an additional degree of control over information erasure or restoration. In an embodiment, as heat is transferred to a surface with stored information, those areas with lower transition temperature compositions will erase first. Information stored at areas with higher transformation temperature compositions will remain until exposed to the higher temperature. In another embodiment, as heat is transferred to a surface where information was previously stored, those areas with lower transition temperature compositions will restore first. Information previously stored at areas with higher transformation temperature compositions will remain erased until exposed to the higher temperature.
It is to be understood that both thickness variation and/or composition variation may be used with bulk material heating to selectively erase or restore specific, predetermined areas. Still firther, dimensional and/or composition variations may be combined with any of the embodiments disclosed herein for additional control over selective erasing or restoring.
In the non-limitative example shown in FIG. 8, a first area 20 may have a thickness TI and/or a composition (illustrated with triangles) that is different from a thickness T2 and/or composition (illustrated with circles) of a second area 22. As such, information stored or previously stored at the first area 20 may be erased or restored at one temperature for a predetermined time, and the information stored or previously stored at the second area 22 may be erased or restored at a temperature and for a time different from that used to erase or restore information stored at the first area 20. As such, the entire shape memory material 10 may be exposed to heat or cooling; however, information stored or previously stored at those areas with a transition temperature higher (due at least in part to the thickness and/or composition) than the temperature to which the material 10 is exposed will not be erased or restored.
In the embodiments disclosed herein, it is to be understood that the elements 14 in the array 100 may be intelligently controlled and optimized via any suitable electronic device. An intelligent control system may be used to heat/cool predetermined elements 14 in the array 100, taking into account any dimensional and/or composition variations, for predetermined times such that the desired information is erased or restored.
Embodiments of the method disclosed herein advantageously allow a user to selectively erase information from a shape memory material 10 or restore information to a shape memory material by selectively applying heat or cooling.
While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.

Claims

1. A method for at least one of selectively erasing information from and restoring information to a shape memory material, the method comprising at least one of selectively heating and selectively cooling, to a predetermined temperature and for a predetermined time, at least a portion of at least one heating element or cooling element adjacent a predetermined area of the shape memory material, thereby at least one of erasing the information stored therein and restoring information therein, wherein the at least one heating element or cooling element is located in an array of at least one of heating elements and cooling elements.

2. The method as defined in claim 1 wherein prior to at least one of selectively heating and selectively cooling, the method further comprises establishing the predetermined area of the shape memory material adjacent the at least a portion of the at least one heating element or cooling element to be selectively heated or cooled.

3. The method as defined in claim 1 wherein the shape memory material is established on a substrate having the array incorporated therein.

4. The method as defined in claim 1 wherein at least one of the heating or cooling elements in the array crosses at least an other of the heating or cooling elements in the array at a non-zero angle to form a junction, and wherein the at least one and the at least an other of the heating or cooling elements are at least one of selectively heated and selectively cooled such that a temperature produced by the at least one and the at least an other of the heating or cooling elements at the junction is sufficient to at least one of erase information from and restore information to the shape memory material adjacent the junction.

5. The method as defined in claim 4 wherein the heating elements or cooling elements in the array are selected from nanotubes, wires, fluid channels, lasers, conductive fibers, interconnected pores, and combinations thereof.

6. The method as defined in claim 1 wherein the heating elements or cooling elements in the array are selected from nanotubes, channels, and interconnected pores, and wherein at least one of selectively heating and selectively cooling is accomplished by directing heated or cooled fluid through at least a portion of at least one of the nanotubes, channels, or a flow path created by the interconnected pores adjacent the predetermined area of the shape memory material.

7. The method as defined in claim 1 wherein the heating elements or cooling elements in the array are wires, and wherein at least one of selectively heating and selectively cooling is accomplished by resistively heating or cooling at least a portion of at least one of the wires adjacent the predetermined area of the shape memory material.

8. The method as defined in claim 1 wherein the heating elements or cooling elements in the array are selected from nanotubes and conductive fibers, and wherein at least one of selectively heating and selectively cooling is accomplished by resistively heating or cooling at least a portion of at least one of the nanotubes and the conductive fibers adjacent the predetermined area of the shape memory material.

9. The method as defined in claim 1 wherein the shape memory material is selected from shape memory alloys, shape memory polymers, and combinations thereof.

10. The method as defined in claim 1 wherein the shape memory material has at least one of a varying dimension or a varying composition.

11. The method as defined in claim 10 wherein the at least one varying dimension is shape memory material thickness such that a portion of the shape memory material has a first thickness and at least an other portion of the shape memory material has a second thickness different from the first thickness, and wherein the predetermined time and the predetermined temperature for at least one of selectively heating and selectively cooling adjacent the first thickness is different from the predetermined time and the predetermined temperature at least one of selectively heating and selectively cooling adjacent the second thickness.

12. The method as defined in claim 10 wherein the shape memory material has a first composition at a portion and a second composition that is different from the first composition at an other portion, wherein the predetermined time and the predetermined temperature for at least one of selectively heating and selectively cooling adjacent the first composition is different from the predetermined time and the predetermined temperature for at least one of selectively heating and selectively cooling adjacent the second composition.

13. The method as defined in claim 1 wherein the array is established in the shape memory material.

14. The method as defined in claim 1 wherein the shape memory material is established on a substrate having an elastic modulus between a low temperature state and a high temperature state of the shape memory material.

15. The method as defined in claim 1 wherein the array is operatively disposed in a stylus.

16. The method as defined in claim 1 wherein the at least one heating element or cooling element is intelligently controlled.

17. A method for at least one of selectively erasing information from and selectively restoring information to a shape memory material, the method comprising:

establishing a predetermined area of the shape memory material adjacent a junction formed by at least two crossing heating elements or cooling elements; and

at least one of selectively heating and selectively cooling the junction to a predetermined temperature and for a predetermined time, thereby at least one of erasing information stored in and restoring information to the shape memory material adjacent the junction.

18. The method as defined in claim 17 wherein the shape memory material adjacent the first junction has at least one of a dimension and composition different from that of the shape memory material adjacent the second junction; and wherein at least one of the predetermined temperature and the predetermined time for at least one of selectively heating and selectively cooling the first junction is different from at least one of the predetermined temperature and predetermined time for at least one of selectively heating and selectively cooling the second junction.

19. A method for at least one of selectively erasing information from and selectively restoring information to a shape memory material, the method comprising at least one of selectively heating and selectively cooling, to a predetermined temperature and for a predetermined time at least a portion of at least one heating element or cooling element adjacent a predetermined area of the shape memory material, thereby erasing or restoring the information, wherein the at least one heating element or cooling element is located in an array of heating or cooling elements, and wherein the predetermined temperature and the predetermined time for at least one of selectively heating and selectively cooling a first area of the shape memory material is different from the predetermined time and the predetermined temperature for at least one of selectively heating and selectively cooling a second area of the shape memory material.

20. An apparatus, comprising:

a shape memory material layer adapted to have information stored therein; and

an array of heating or cooling elements, at least one heating or cooling element in the array being adjacent to or within a predetermined area of the shape memory material layer;

wherein at least a portion of the at least one heating or cooling element is adapted to be selectively heated or selectively cooled to a predetermined temperature and for a predetermined time, thereby at least one of erasing the information from and restoring the information to the predetermined area of the shape memory material layer.