Shape memory alloy actuators

• US 7,658,709 B2
• Filed: 04/09/2003
• Issued: 02/09/2010
• Est. Priority Date: 04/09/2003
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Anderson, David A., Istephanous, Naim S., Waldhauser, Steven L., Kelley, James F.
• Primary Examiner(s): Hindenburg; Max
• Assistant Examiner(s): TOWA, RENE T
• Application Number:
  US10/410,546
• Publication Number:
  US 20040204676A1
• Time in Patent Office: 2,498 Days
• Field of Search: 600/143, 600/151, 604/95.04, 604/95.05, 606/78, 623/1.18, 60527-529
• US Class Current: 600/143
• 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, a groove being defined in the surface of the SMA substrate establishing a trace pattern;

an electrically insulative layer formed within the groove;

a conductive trace formed upon the electrically insulative layer within the groove and electrically isolated from the SMA substrate by the electrically insulative layer formed within the groove, the conductive trace including a first end, a second end, and a heating element disposed between the first end and the second end, wherein at least portions of the conductive trace, portions of the electrically insulative layer electrically isolating the conductive trace from the SMA substrate within the groove, and portions of the SMA substrate are flush after the conductive trace has been formed upon the electrically insulative layer within the groove;

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

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

4. The medical device of claim 2, wherein the organic material comprises a fluoropolymer.

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

6. The medical device of claim 2, wherein the organic material comprises 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 of 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 functionally 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 functionally 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 functionally sufficient for an applied operating voltage between approximately 1V and approximately 10V.

12. The medical device of claim 1, wherein the insulative layer comprises a composite of an inorganic material and an organic material wherein the organic material is selected from the group consisting of fluoropolymer, parylene, and benzocyclobutene.

13. The medical device of claim 12, wherein the inorganic material is selected from a group consisting of oxides, nitrides, and carbides.

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

an SMA substrate including a surface, a groove being defined in the surface of the SMA substrate establishing a trace pattern;

an electrically insulative layer formed within the groove;

a conductive trace formed upon the electrically insulative layer within the groove and electrically isolated from the SMA substrate by the electrically insulative layer formed within the groove, the trace including a first end, a second end, and a heating element disposed between the first end and the second end, wherein at least portions of the conductive trace, portions of the electrically insulative layer electrically isolating the conductive trace from the SMA substrate within the groove, and portions of the SMA substrate are flush after the conductive trace has been formed upon the electrically insulative layer within the groove;

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.

15. The SMA actuator of claim 14, wherein the insulative layer comprises an organic material.

16. The SMA actuator of claim 15, wherein the organic material is polyimide.

17. The SMA actuator of claim 15, wherein the insulative layer comprises a fluoropolymer.

18. The SMA actuator of claim 15, wherein the organic material comprises parylene.

19. The SMA actuator of claim 15, wherein the organic material comprises benzocyclobutene.

20. The SMA actuator of claim 14, 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.

21. The SMA actuator of claim 14, wherein the insulative layer comprises a composite of an inorganic material and an organic material being one of fluoropolymer, parylene, and benzocyclobutene.

22. The SMA actuator of claim 21, wherein the inorganic material is selected from a group consisting of oxides, nitrides, and carbides.

23. The SMA actuator of claim 14, wherein a thickness of the electrically insulative layer over which the conductive trace is formed is less than approximately 0.5 micrometer.

24. The SMA actuator of claim 14, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is functionally sufficient for an applied operating voltage greater than approximately 100V.

25. The SMA actuator of claim 14, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is functionally sufficient for an applied operating voltage greater than approximately 10V.

26. The SMA actuator of claim 14, wherein a dielectric strength of the electrically insulative layer over which the conductive trace is formed is functionally sufficient for an applied operating voltage between approximately 1V and approximately 10V.

27. 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, a groove being defined in the surface of the SMA substrate establishing a trace pattern;

an electrically insulative layer formed within the groove;

a conductive trace formed upon the electrically insulative layer within the groove and electrically isolated from the SMA substrate by the electrically insulative layer formed within the groove, the trace including a first end, a second end, and a heating element disposed between the first end and the second end, wherein at least portions of the conductive trace, portions of the electrically insulative layer electrically isolating the conductive trace from the SMA substrate within the groove, and portions of the SMA substrate are flush after the conductive trace has been formed upon the electrically insulative layer within the groove;

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, the transition temperature being achieved when electricity is conducted through the conductive trace via the first and second interconnect pads, and

wherein the insulative layer comprises a composite of an inorganic material and an organic material.

28. The elongated medical device of claim 27, wherein the composite comprises a first layer comprising the inorganic material and a second layer comprising the organic material.