Advanced layered composite polylaminate electroactive actuator and sensor

• US 6,060,811 A
• Filed: 07/25/1997
• Issued: 05/09/2000
• Est. Priority Date: 07/25/1997
• Status: Expired due to Fees

• Current Assignee: National Aeronautics and Space Administration (Government of the United States of America)
• Original Assignee: United States Administrator of National Aeronautics and Space Administration
• Inventors: Copeland, Benjamin M. Jr., Fox, Robert L., Bryant, Robert G., Hellbaum, Richard F.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US08/910,463
• Time in Patent Office: 1,019 Days
• Field of Search: 310/26, 310/306, 310/311, 310/324, 310/328, 310/348
• US Class Current: 310/311
• CPC Class Codes: H10N 30/204 using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders

Abstract

The present invention relates to the mounting of pre-stressed electroactive material in such a manner that large displacement actuators or sensors result. The invention comprises mounting the pre-stressed electroactive material to a support layer. This combination of a pre-stressed electroactive material and support layer may in turn be attached to a mounting surface. The pre-stressed electroactive material may be a ferroelectric, pyroelectric, piezoelectric, or magnetostrictive material. The size, stiffness, mass, and material of the support layer is selected to result in the electroactive device having dynamic response properties, environmental capability characteristics, and the required resilience optimized for a given application. The capacity to connect the support layer to a surface expands the arenas in which the pre-stressed electroactive device may be used. Application for which the invention may be used include actuators, sensors, or as a component in a pumps, switches, relays, pressure transducers and acoustic devices.

Claims

1. An electroactive device, comprising:

a pre-stressed, curved electroactive material having a convex surface and a concave surface;

a support layer having a curved central portion and two ends, the curved central portion having a convex surface and a concave surface, the convex surface being conformed to match to the shape of the concave surface of the pre-stressed curved electroactive material, the convex surface of the central portion being in contact with the concave surface of the pre-stressed, curved electroactive material; and

a means for attaching the convex surface of the central portion of the support layer to the concave surface of the pre-stressed, curved electroactive material.

2. An electroactive device as recited in claim 1 wherein the support layer is selected from the group consisting of metals, plastics and ceramics.

3. An electroactive device as recited in claim 1 wherein the pre-stressed, curved electroactive material is selected from the group consisting of ceramics and metallic alloys.

4. An electroactive device as recited in claim 1 wherein the pre-stressed, curved electroactive material is selected from the group consisting of ferroelectric, piezoelectric, pyroelectric, and magnetostrictive materials.

5. An electroactive device as recited in claim 1 wherein the pre-stressed, curved electroactive material is a piezoelectric material, further comprising a pair of electrodes, one electrode being attached to the convex surface of the pre-stressed, curved electroactive material, the other electrode being attached to the concave surface of the pre-stressed, curved electroactive material.

6. An electroactive device as recited in claim 1 wherein the means for attaching the convex surface of the central portion of the support layer to the concave surface of the pre-stressed, curved electroactive material is selected from the group consisting of adhesives, cerment, braze alloys, soldering, welding, and adhesive bonding.

7. An electroactive device as recited in claim 1 further comprising at least one mounting surface attached to at least one end of the support layer.

8. An electroactive device as recited in claim 7 wherein the mounting surface is chosen from the group consisting of metals, plastics, ceramics, composites and organic materials.

9. An electroactive device as recited in claim 7 wherein the mounting surface is a flexible layer.

10. An electroactive device as recited in claim 7 wherein the means for attaching at least one end of the support layer to the mounting surface is chosen from the group consisting of welding, brazing, soldering, bolting, riveting, crimping, clamping, hinging, mechanical fastening, mechanical interlocking, and adhesive bonding.

11. An electroactive device, comprising:

at least one pre-stressed, curved electroactive material having a convex surface and a concave surface;

at least one support layer having a curved central portion and two ends, the curved central portion having a convex surface and a concave surface, the convex surface being conformed to match to the shape of the concave surface of the pre-stressed curved electroactive material, the convex surface of the central portion being in contact with the concave surface of the pre-stressed, curved electroactive material; and

a means for attaching the convex surface of the central portion of the support layer to the concave surface of the pre-stressed, curved electroactive material.