Laser machining of electroactive ceramics

• US 6,337,465 B1
• Filed: 03/09/1999
• Issued: 01/08/2002
• Est. Priority Date: 03/09/1999
• Status: Expired due to Term

• Current Assignee: Mide Technology Corporation (Totalenergies Se)
• Original Assignee: Mide Technology Corporation (Totalenergies Se)
• Inventors: Masters, Brett P., Rodgers, John P., van Schoor, Marthinus C.
• Primary Examiner(s): Dunn, Tom
• Assistant Examiner(s): JOHNSON, JONATHAN J
• Application Number:
  US09/264,113
• Time in Patent Office: 1,036 Days
• Field of Search: 219/121.85, 219/121.69, 219/121.68, 219/121.67, 427/100, 29/253.5, 310/330, 310/369, 367/140, 367/155, 367/156, 367/157, 367/160
• US Class Current: 219/121.85
• CPC Class Codes: H10N 30/085 by machining
• CPC Class Codes: H10N 30/097 by sintering
• CPC Class Codes: H10N 30/204 using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders

Abstract

Laser beam machining is applied to form arbitrarily shaped electroactive ceramics for transducers (e.g., electromechanical sensors and actuators). One particularly preferred embodiment of the invention comprises machining parallel grooves in a ceramic plate to improve flexibility. The grooves provide strain relief in bending by relieving Poisson strains transverse to the direction of bending. This embodiment offers the further benefit that planar anisotropy or directionality is introduced in the transducer. The machining process of the invention further enables the production of more complex geometries than those currently known in the art. Because of the flexibility of the machining process, virtually any desired transducer shape may be produced.

Claims

1. A method of producing an electromechanical device, comprising:

poling the electroactive ceramic;

laser machining the electroactive ceramic to form a desired shape, including machining grooves into a surface of the electroactive ceramic; and

incorporating the electroactive ceramic into an electromechanical sensor or actuator.

2. The method of claim 1, further comprising depositing an electrode material into the grooves in the surface of the electroactive ceramic.

3. The method of claim 1, further comprising depositing an electrode material onto a surface of the electroactive ceramic produced by laser machining.

4. The method of claim 1, wherein the produced sensor or actuator is a strain-relieved, planar transducer.

5. The method of claim 1, wherein the electroactive ceramic is selected from the group consisting of piezoelectric ceramics and electrostrictive ceramics.

6. The method of claim 1, wherein poling the electroactive ceramic precedes laser machining.

7. The method of claim 1, wherein poling the electroactive ceramic follows laser machining.

8. The method of claim 1, wherein the electroactive ceramic comprises grooves which render its electromechanical properties anisotropic.

9. The method of claim 1, wherein at least 1% of the electroactive ceramic is removed during laser machining.

10. The method of claim 9, wherein at least 5% of the electroactive ceramic is removed during laser machining.

11. The method of claim 9, wherein at least 20% of the electroactive ceramic is removed during laser machining.

12. The method of claim 9, wherein at least 50% of the electroactive ceramic is removed during laser machining.

13. The method of claim 9, wherein at least 75% of the electroactive ceramic is removed during laser machining.

14. The method of claim 9, wherein at least 90% of the electroactive ceramic is removed during laser machining.

15. The method of claim 1, wherein the electroactive ceramic possesses a surface area at least 10% greater after machining than its surface area before machining.

16. The method of claim 1, further comprising:

after machining and prior to incorporating the electroactive ceramic into a sensor or actuator, deforming the electroactive ceramic into a substantially three-dimensional shape.