Shape memory alloy actuators

• US 20040204676A1
• Filed: 04/09/2003
• Published: 10/14/2004
• Est. Priority Date: 04/09/2003
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Anderson, David A., Waldhauser, Steven L., Kelley, James F., Istephanous, Naim S.
• Granted Patent: US 7,658,709 B2
• Time in Patent Office: Days
• US Class Current: 604/95.05
• CPC Class Codes: A61L 2400/16 Materials with shape-memory or superelastic properties
• CPC Class Codes: A61L 29/02 Inorganic materials
• CPC Class Codes: A61L 29/085 Macromolecular materials
• CPC Class Codes: A61M 2025/0064 which become stiffer or softer when heated
• CPC Class Codes: A61M 2025/09141 made of shape memory alloys which take a particular shape at a certain temperature
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 25/00 Catheters; Hollow probes dilators A61M29/00; peritoneal catheters A61M1/285; tracheal tubes A61M16/04; for drainage A61M27/00; for uterus, vagina or rectum A61M31/00 ; for measuring or testing A61B; materials for catheters A61L29/00
• CPC Class Codes: A61M 25/09 Guide wires
• CPC Class Codes: F03G 7/065 using a shape memory element
• CPC Class Codes: F16K 31/025 actuated by thermo-electric means
• CPC Class Codes: Y10T 83/0304 Grooving

Abstract

A shape memory alloy (SMA) actuator includes a groove formed in a surface of a shape memory alloy (SMA) substrate establishing a trace pattern for a layer of conductive material formed over an electrically insulative layer. The trace pattern includes a first end, a second end, and a heating element disposed between the first and second ends. The SMA substrate is trained to deform at a transition temperature achieved when electricity is conducted through the conductive material via first and second interconnect pads terminating the first and second ends of the trace pattern.

Claims

1. An elongated medical device adapted for controlled deformation by means of one or more actuators, the one or more actuators comprising:

a shape memory alloy (SMA) substrate including a surface, the surface including a groove establishing a trace pattern;

an electrically insulative layer formed upon a portion of the surface of the SMA substrate including the groove;

a conductive trace formed upon the electrically insulative layer in the trace pattern, the trace including a first end, a second end, and a heating element disposed between the first end and the second end;

a first interconnect pad terminating the first end of the trace; and

a second interconnect pad terminating the second end of the trace;

wherein the SMA substrate is trained to deform at a transition temperature achieved when electricity is conducted through the conductive trace via the first and second interconnect pads.

2. The device of claim 1, wherein the insulative layer comprises an organic material.

3. The device of claim 2, wherein the organic material is a fluoropolymer.

4. The device of claim 2, wherein the organic material is polyimide.

5. The device of claim 2, wherein the organic material is parylene.

6. The device of claim 2, wherein the organic material is benzocyclobutene.

7. The medical device of claim 1, wherein a thickness of the electrically insulative layer over which the conductive trace is formed is between approximately 0.5 micrometer and approximately 1 micrometer.

8. The medical device of claim 1, wherein a thickness the electrically insulative layer over which the conductive trace is formed is less than approximately 0.5 micrometer.

9. The medical device of claim 1, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is sufficient for an applied operating voltage greater than approximately 100V.

10. The medical device of claim 1, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is sufficient for an applied operating voltage greater than approximately 10V.

11. The medical device of claim 1, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is sufficient for an applied operating voltage between approximately 1V and approximately 10V.

12. A method for manufacturing a shape memory alloy (SMA) actuator, comprising forming a groove on a surface of an SMA substrate to establish a trace pattern.

13. The method of claim 12, further comprising forming a layer of electrically insulative material on the surface of the SMA substrate including the groove.

14. The method of claim 13, further comprising forming a layer of conductive material over the insulative layer.

15. The method of claim 14, further comprising removing insulative material and conductive material from a portion of the surface of the SMA substrate not including the groove, leaving behind insulative material and conductive material in the groove.

16. A shape memory alloy (SMA) actuator comprising:

an SMA substrate including a surface, the surface including a groove establishing a trace pattern;

an electrically insulative layer formed upon a portion of the surface of the SMA substrate including the groove;

a conductive trace formed upon the electrically insulative layer in the trace pattern, the trace including a first end, a second end, and a heating element disposed between the first end and the second end;

a first interconnect pad terminating the first end of the trace; and

a second interconnect pad terminating the second end of the trace;

wherein the SMA substrate is trained to deform at a transition temperature achieved when electricity is conducted through the conductive trace via the first and second interconnect pads.

17. The device of claim 16, wherein the insulative layer comprises an organic material.

18. The device of claim 17, wherein the organic material is a fluoropolymer.

19. The device of claim 17, wherein the organic material is polyimide.

20. The device of claim 17, wherein the organic material is parylene.

21. The device of claim 17, wherein the organic material is benzocyclobutene.

22. The medical device of claim 16, wherein a thickness of the electrically insulative layer over which the conductive trace is formed is between approximately 0.5 micrometer and approximately 1 micrometer.

23. The medical device of claim 16, wherein a thickness the electrically insulative layer over which the conductive trace is formed is less than approximately 0.5 micrometer.

24. The medical device of claim 16, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is sufficient for an applied operating voltage greater than approximately 100V.

25. The medical device of claim 16, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is sufficient for an applied operating voltage greater than approximately 10V.

26. The medical device of claim 16, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is sufficient for an applied operating voltage between approximately 1V and approximately 10V.