ELECTROACTIVE ACTUATOR AND METHOD FOR ITS PRODUCTION

• US 20170186941A1
• Filed: 03/31/2015
• Published: 06/29/2017
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: BENWADIH, Mohammed, ALIANE, Abdelkader
• Granted Patent: US 10,305,023 B2
• Time in Patent Office: Days
• CPC Class Codes: H10N 30/05 Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
• CPC Class Codes: H10N 30/067 Forming single-layered electrodes of multilayered piezoelectric or electrostrictive parts
• CPC Class Codes: H10N 30/098 Forming organic materials
• CPC Class Codes: H10N 30/50 having a stacked or multilayer structure
• CPC Class Codes: H10N 30/857 Macromolecular compositions
• CPC Class Codes: H10N 30/87 Electrodes or interconnections, e.g. leads or terminals
• CPC Class Codes: H10N 30/871 Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes

Abstract

The invention relates to a method for manufacturing an electroactive actuator from a stack comprising a first electrode (20) and a layer comprising an electroactive polymer superposed on the electrode (20), the electroactive polymer being deformed when it is in a crystalline state and when an electric field is applied thereto, with the method comprising:

• • a step of obtaining an electroactive layer (30) comprising a step of crystallisation the layer comprising the electroactive polymer superposed on the stack;
  • a step of forming a second electrode (21) in such a way that the electroactive layer (30) is disposed between the two electrodes (20, 21);
    characterised in that the electroactive polymer is formed from a material which crystallises under the effect of an ultraviolet flash and in that the crystallisation step includes a UV flash step.

The invention further relates in particular to electroactive actuator.

Claims

1-36. -36. (canceled)

37. A method for manufacturing an electroactive actuator from a stack comprising at least one first electrode and at least one layer comprising an electroactive polymer superposed on the first electrode, with the electroactive polymer having the capacity to respond by a displacement when it is in a crystalline state and when an electric field is applied thereto, the method comprising:

obtaining an electroactive layer by crystallizing a layer comprising the electroactive polymer superposed on the stack; and

forming a second electrode in such a way that the electroactive layer is disposed between the first and the second electrodes;

wherein;

the electroactive polymer is formed of a material able to crystallise at least partially under the effect of an exposure to ultra-violet (UV) radiation; and

the crystallizing comprises exposing the electroactive layer to ultra-violet radiation during which a portion at least of the ultra-violet radiation is delivered in the form of one or several pulses, with the duration of each pulse being less than 100 milliseconds (ms) (10<sup>−

3</sup> seconds).

38. The method according to claim 37, wherein using the stack comprising at least one layer comprising an electroactive polymer arranged between two electrodes, the following sequence of steps is carried out:

formation of an additional layer of electroactive polymer superposed on said stack;

obtaining of an additional electroactive layer by crystallisation of said additional layer of electroactive polymer, with the crystallisation comprising a step of exposure of the additional layer of electroactive polymer to UV radiation, with the step of exposure comprising the pulse or pulses;

formation of an electrode superposed on said additional electroactive layer.

39. The method according to claim 38, wherein said sequence of steps is reiterated in such a way as to obtain a stack of a plurality of electro active layers with each one having been subjected to an independent step of exposure of the electroactive layer to ultra-violet radiation and each one located between two electrodes.

40. The method according to claim 39, wherein the plurality of electroactive layers comprises at least three electroactive layers.

41. The method according to claim 37, wherein the duration of each pulse is less than 10 ms, and wherein the duration of exposure is between 0.5 ms and 3 ms, and wherein during the step of exposure the ultra-violet radiation is delivered in the form of one or several pulses, with the fluence of each one of the pulses being less than 50 j/cm².

42. The method according to claim 37, wherein the step of crystallisation comprises only said step of exposure, and wherein the electroactive layer is constituted solely of the electroactive polymer.

43. The method according to claim 37, wherein the stack rests on a substrate that is sufficiently flexible to follow the displacement of the stack.

44. The method according to claim 37, wherein at least some of the electrodes of the actuator are metal electrodes.

45. The method according to claim 37, wherein at least some of the electrodes of the actuator are made of graphene or are formed from a silver ink on nanowires.

46. The method according to claim 37, wherein the stack comprises several electroactive layers and wherein after crystallisation of a lower electroactive layer and before the formation of a second upper electroactive layer superposed on the lower electroactive layer, a blocking layer of the UV is carried out arranged between the lower and upper electroactive layers, said blocking layer comprising at least one non-metal compound that absorbs or blocks the UV, in such a way that the blocking layer of the UV blocks at least a portion of the UV passing through the upper electroactive layer and being directed to the lower electroactive layer, and wherein the blocking layer of the UV blocks at least 50% of the UV passing through the upper electroactive layer and being directed to the lower electroactive layer.

47. The method according to claim 46, wherein the non-metal compound that absorbs or blocks the UV is an comprising a thiol bond (—

SH).

48. The method according to claim 46, wherein the blocking layer is formed by the electrode separating the upper electroactive layer from the lower electroactive layer, wherein the non-metal compound that absorbs or blocks the UV forms a thiol bond (—

SH) and wherein the concentration in thiol bonds in the electrode is between 0.5% to 10% by weight.

49. The method according to claim 46, wherein the blocking layer and the electrode separating the upper electroactive layer from the lower electroactive layer form the same layer, said electrode comprising the non-metal compound that absorbs or blocks the UV.

50. The method according to claim 37, wherein the formation of the second electrode comprises a step of deposition of a metal solution by inkjet, screen printing or by ultrasonic spraying, wherein the formation of the blocking layer comprises the incorporation of thiol bonds to the metal solution, and wherein the incorporation is carried out by mixing the thiol bonds to the metal solution before deposition of the metal solution.

51. The method according to claim 46, wherein the blocking layer is a separate layer from the electrode separating the upper electroactive layer from the lower electroactive layer, with the blocking layer being located between said electrode and one from among the upper electroactive layer and the lower electroactive layer.

52. The method according to claim 37, wherein the electroactive layers are made of Poly vinylidenefluoride-Trifluoroethylene-chloro-fluoroethylene) (P(VDF-TrFe-CFE)) or of Poly(vinylidenefluoride-Trifluoroethylene-chloro trifluoroethylene) (P(VDF-TrFe-CTFE)).

53. The method according to claim 37, wherein the stack comprises more than two electrodes and wherein only two electrical contacts are formed, configured to apply a potential difference over the entire stack.

54. An electroactuator, comprising a stack comprising a plurality of superimposed electroactive layers, each one associated with two electrodes,

wherein at least some of the electroactive layers comprise an electroactive polymer able to crystallise at least partially under the effect of an exposure to ultra-violet radiation and in that it comprises, between two superimposed electroactive layers, at least one layer comprising at least one non-metal compound that absorbs or blocks the UV.

55. The electroactuator according to claim 54, wherein the non-metal compound that absorbs or blocks the UV is an organic compound comprising a thiol bond (—

SH).

56. A device, comprising one or several electroactuators according to claim 54.