Electroactive actuators, systems equipped therewith, and methods of use and manufacture

• US 9,683,663 B2
• Filed: 01/25/2013
• Issued: 06/20/2017
• Est. Priority Date: 01/25/2012
• Status: Active Grant

• Current Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Original Assignee: Purdue Research Foundation (The Trustees of Purdue University (d/b/a Purdue University))
• Inventors: Newell, Brittany Ann, Krutz, Gary William
• Primary Examiner(s): San Martin, J.
• Application Number:
  US14/371,448
• Publication Number:
  US 20150091254A1
• Time in Patent Office: 1,607 Days
• Field of Search: 310328, 310800
• CPC Class Codes: F16J 15/008 with provision to put out of action at least one sealing; One sealing sealing only on standstill; Emergency or servicing sealings F16J15/164 takes precedence
• CPC Class Codes: F16J 15/022 characterised by structure or material
• CPC Class Codes: F16J 15/068 the packing swelling under working conditions
• CPC Class Codes: F16J 15/3284 characterised by their structure; Selection of materials
• CPC Class Codes: H10N 30/206 using only longitudinal or thickness displacement, e.g. d33 or d31 type devices
• 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 30/878 the principal material being non-metallic, e.g. oxide or carbon based

Abstract

Actuators and methods utilizing electrical properties of polymer materials. The actuators have a multilayer structure that includes an electroactive polymer layer between and bonded to first and second electrodes so that the polymer layer has a thickness dimension therebetween. The multilayer structure is adapted so that application of an electric potential to the electrodes causes the electroactive polymer layer to expand in at least one dimension thereof transverse to the thickness dimension of the electroactive polymer layer. The actuators can be used in sealing elements to provide a resealing capability once a condition has occurred of a type that may precede a seal failure.

Claims

1. An actuator having a multilayer structure comprising:

first and second electrodes formed of electrically-conductive polymer materials; and

an electroactive polymer layer formed of a dielectric elastomer, the electroactive polymer layer being between and bonded to the first and second electrodes so as to have a thickness dimension therebetween;

wherein the multilayer structure is adapted so that applying an electric potential to the first and second electrodes causes the electroactive polymer layer to expand in at least one dimension thereof transverse to the thickness dimension of the electroactive polymer layer;

wherein the electroactive polymer layer is in a strain memory state induced by a pre-straining technique that expands the electroactive polymer layer and then releases the electroactive polymer layer to allow the electroactive polymer layer to substantially shrink to pre-strained dimensions thereof prior to bonding of the first and second electrodes thereto.

2. The actuator according to claim 1, wherein the strain memory state was induced by a chemical pre-straining technique that swells the dielectric material and then allows the electroactive polymer layer to substantially shrink to pre-swelled dimensions thereof prior to bonding of the first and second electrodes thereto.

3. The actuator according to claim 1, wherein the actuator further comprises an elastomeric core completely surrounded by the multilayer structure.

4. The actuator according to claim 3, wherein the electroactive polymer layer is a first electroactive polymer layer of the actuator, and the actuator further comprises a second layer of an electroactive polymer material between and bonded to the elastomeric core and the first electrode.

5. The actuator according to claim 4, wherein the second layer of the electroactive polymer material is in a strain memory state induced by a pre-straining technique that expands the second layer and then releases the second layer to allow the second layer to substantially shrink to pre-strained dimensions thereof prior to bonding the elastomeric core and the first electrode thereto.

6. The actuator according to claim 4, wherein the second layer of the electroactive polymer material is in a strain memory state induced by a chemical pre-straining technique that swells the second layer and then allows the second layer to substantially shrink to pre-swelled dimensions thereof prior to bonding of the elastomeric core and the first electrode thereto.

7. The actuator according to claim 1, the actuator further comprising means for monitoring distortion of the actuator, the actuator being connected to means for applying the electric potential in response to the monitoring means, wherein the monitoring means comprises:

an electrically-conductive polymer sensing element integrally incorporated into the actuator;

means for applying a second electric potential to the polymer sensing

means for sensing an electric signal generated by the polymer sensing element in response to the polymer sensing element physically responding to distortion of the actuator; and

means for applying the electric potential to the first and second electrodes if the electric signal exceeds a predetermined threshold value corresponding to the distortion of the actuator attaining a predetermined level.

8. The actuator according to claim 1, wherein the actuator is a sealing element.

9. The actuator according to claim 8, wherein the sealing element has an annular shape, the multilayer structure completely surrounds an elastomeric core, the sealing element is disposed in a groove, distortion of the sealing element causes the sealing element to occupy a reduced cross-sectional area of the groove, and applying the electric potential to the first and second electrodes causes the sealing element to expand to occupy an increased cross-sectional area of the groove.