摘要：
Various methods of additive layer manufacturing, and objects obtainable by such manufacturing, are disclosed. In particular, there is provided a method of additive layer manufacturing comprising depositing a layer of a material on a surface, and controlling the deposition to vary a material property of the material within the layer. There is also provided a method of additive layer manufacturing comprising depositing at least one layer of material on a sacrificial layer, the layer of material having a thickness of 400 microns or less, wherein the sacrificial layer is located on a base surface.
技术问题语段：
The patent text describes a method of additive layer manufacturing that allows for the production of complex items with variations of physical or material properties on a fine scale. The technical problem addressed by this invention is the difficulty of producing very thin parts or parts with very thin layers in conventional methods of additive layer manufacturing. The method involves depositing layers of material with controlled variations in material properties, such as polymer chain alignment, optical properties, refractive index, and birefringence. The deposition can be controlled by varying the speed of the print head and the surface, the rate of material feed, and the extrusion factor. The method can also involve sequentially depositing layers of different materials to achieve the desired properties. The resulting objects made using this method have improved strength and flexibility.
技术功效语段：
The present invention provides a method of additive layer manufacturing that can produce complex items with variations in physical or material properties on a fine scale. This is achieved by controlling the deposition of material to vary the material property of the material within the layer. The method can control the thickness of the layer, the speed of the print head and the surface, the rate at which material is fed to the print head, the extrusion factor, the distance between the print head and the surface, and the temperature of the surface. The invention also allows for sequential deposition of layers with different materials, resulting in the combination of different materials in a controlled way. The resulting objects have improved properties and can be used for various applications such as photonic devices and cardiac stents.
权利要求：
CLAIMS
1. A method of additive layer manufacturing comprising: depositing a layer of a material on a surface; and controlling the deposition to vary a material property of the material within the layer.
2. The method according to claim 1, wherein the depositing is carried out by moving a print head in a first direction relative to the surface, and the variation of the material property is along the layer in the first direction.
3. The method according to claim 1 or 2, wherein the material property is polymer chain alignment.
4. The method according to any preceding claim, wherein the material property is refractive index.
5. The method according to any preceding claims, wherein the material property is retardation.
6. The method according to any preceding claim, wherein the material property is birefringence.
7. The method according to any preceding claim, wherein the controlling includes varying the relative speed of a print head and the surface on which the layer of material is deposited.
8. The method according to any preceding claim, wherein the controlling includes varying the rate at which material is fed to a print head.
9. The method according to any preceding claim, wherein the controlling includes varying the extrusion factor, the extrusion factor being the ratio of the length of filament extruded by a print head to the distance travelled by the print head.
10. The method according to any preceding claim, wherein the controlling comprises varying the distance between a print head and the surface on which the layer of material is deposited.
11. The method according to any preceding claim, wherein the controlling comprises varying an extensional force applied to the material to thereby vary the material property.
12. The method according to any preceding claim, wherein the controlling comprises varying a strain rate applied to the material to thereby vary the material property.
13. The method according to any preceding claim, wherein the controlling comprises spatially and/or temporally varying the temperature of the surface on which the material is deposited to thereby vary the material property.
14. The method according to any preceding claim, wherein the material property is degree of crystallinity.
15. The method according to any preceding claim, wherein the controlling comprises controlling orientation of crystallisation by controlling polymer chain alignment within the layer.
16. The method according to any preceding claim, wherein the method comprises sequentially depositing two layers of material, and the deposition is controlled to vary the thickness of both layers
17. The method according to claim 16, wherein the two layers are formed of different materials.
18. The method according to claim 16 or 17, wherein the thickness of the two layers varies such that the total combined thickness of the two layers is constant along the layers.
19. The method according to any preceding claim, wherein the method comprises sequentially depositing a plurality of layers of material, and the deposition is controlled to vary at least one material property along at least one layer.
20. The method according to any preceding claim, wherein the layer of material is deposited on a sacrificial layer, the layer of material having a thickness of 200 microns or less, wherein the sacrificial layer is located on a base surface.
21. The method according to any preceding claim, comprising forming a photonic device.
22. The method according to any one of claims 1-20, comprising forming a cardiac stent.
23. A photonic device comprising one or more layers of polymeric material, wherein at least one material property varies within at least one layer.
24. A cardiac stent comprising a plurality of elongate struts, wherein at least one strut comprises at least one layer, and wherein at least one material property varies within the layer.
25. The stent according to claim 24, wherein the stent is formed of a polymeric material.
26. The photonic device according to claim 23 or the cardiac stent according to claim 24 or 25, wherein the at least one layer is produced using additive manufacturing.
27. A method of additive layer manufacturing comprising depositing at least one layer of material on a sacrificial layer, the layer of material having a thickness of 400 microns or less; wherein the sacrificial layer is located on a base surface.
28. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27, wherein the method further comprises removing the sacrificial layer and the layer of material from the base surface.
29. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27 or 28, wherein the method further comprises removing the sacrificial layer from the layer of material.
30. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27-29, wherein the method includes depositing the sacrificial layer on the base surface before depositing the layer of material.
31. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27-30, wherein the depositing of the sacrificial layer provides a level surface for the deposition of subsequent layers.
32. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27-31, wherein the same apparatus is used to deposit the sacrificial layer and the layer of material.
33. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27-32, further comprising applying a pattern to the surface of the sacrificial layer before depositing the layer of material on the sacrificial layer.
34. The method according to any one of claims 20, or 21 or 22 when dependent on claim 20, or 27-33, further comprising controlling the deposition of the sacrificial layer to vary its thickness.
35. The method according to any one of claims 27-34, wherein the method further comprises controlling the deposition to vary at least one material property of the material along the layer.
36. The method according to any one of claims 1-22 and 27-35, wherein the additive layer manufacturing is fused filament fabrication.
37. An object obtainable by the method of any preceding method claim.
38. The object according to claim 37, wherein the object is a cardiac stent.
39. The object according to claim 37, wherein the object is a photonic device.
40. The object according to claim 37, wherein the object contains hidden information represented by the change in material property.
41. The object according to claim 37 or 40, wherein the object is a physical unclonable function.
42. The object according to claim 40 or 41, wherein the hidden information is an image.
43. The object according to any one of claims 40 to 42, wherein the material property is refractive index and/or birefringence.
44. The object according to claim 42 or 43, wherein the image is a colour image.
45. The object according to claim 42 or 43, wherein the image is a black and white image.