ULTRASONIC TRANSDUCER FOR A METALLIC CAVITY IMPLATED MEDICAL DEVICE

• US 20080021509A1
• Filed: 07/20/2007
• Published: 01/24/2008
• Est. Priority Date: 07/21/2006
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Chavan, Abhijeet V., Maile, Keith R., Mi, Bin
• Granted Patent: US 7,949,396 B2
• Time in Patent Office: Days
• US Class Current: 607/32
• CPC Class Codes: A61B 5/0028 Body tissue as transmission medium, i.e. transmission systems where the medium is the human body
• CPC Class Codes: A61N 1/37217 characterised by the communication link, e.g. acoustic or tactile
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient

Abstract

An implantable medical device comprising a housing and an ultrasonic transducer having a communication frequency coupled to a portion of the housing. The housing resonates at the communication frequency, and a casing is coupled to the housing and disposed over the ultrasonic transducer. The casing is adapted to amplify the deformation of the ultrasonic transducer in a bending mode and transfer the bending moment to the housing. An implantable medical device comprising a housing having an upper portion and a lower portion. A first ultrasonic transducer is coupled to a first connection rod and is coaxial with the first connection rod. The first ultrasonic transducer and first connection rod are interposed between the upper and lower portions such that the first ultrasonic transducer is adapted to vibrate the upper and lower portions simultaneously. A method of optimizing an ultrasonic transducer and a housing of an implantable medical device.

Claims

1. An implantable medical device comprising:

a housing;

an ultrasonic transducer having a communication frequency coupled to a portion of the housing, wherein the housing resonates at the communication frequency; and

a casing coupled to the housing and disposed over the ultrasonic transducer, wherein the casing is adapted to amplify the deformation of the ultrasonic transducer in a bending mode and transfer the bending moment to the housing.

2. The implantable medical device of claim 1 wherein the implantable medical device comprises a pulse generator.

3. The implantable medical device of claim 1 wherein the ultrasonic transducer comprises a piezoelectric material.

4. The implantable medical device of claim 3 wherein the piezoelectric material comprises polyvinylidine diflouride (PVDF) material.

5. The implantable medical device of claim 3 wherein the ultrasonic transducer comprises lead magnesium niobate-lead titanate (PMN-PT).

6. The implantable medical device of claim 3 wherein the piezoelectric material comprises a lead zirconate titanate (PZT) material.

7. The implantable medical device of claim 6 wherein the ultrasonic transducer has a circular shape, a diameter of approximately 25.4 millimeters or less, and a thickness of approximately 3 millimeters or less.

8. The implantable medical device of claim 1 wherein the casing has a diameter of greater than approximately 25.4 millimeters, a height of less than approximately 4 millimeters, a top thickness of between approximately 0.2 and 1 millimeter, and a wall thickness of between 3 and 6 millimeters.

9. The implantable medical device of claim 1 wherein the ultrasonic transducer has a mechanical resonance of greater than approximately 20 kiloHertz.

10. The implantable medical device of claim 1 wherein the ultrasonic transducer has a mechanical resonance of approximately 40 kiloHertz.

11. The implantable medical device of claim 1 wherein the housing includes thinned regions having a thinner cross-section than a substantial portion of the housing and the ultrasonic transducer is located adjacent to the thinned regions.

12. The implantable medical device of claim 11 wherein the thinned regions have an annular shape.

13. The implantable medical device of claim 11 wherein the thinned regions have a wavy or corrugated shape.

14. An implantable medical device comprising:

a housing having an upper portion and a lower portion;

a first ultrasonic transducer coupled to a first connection rod and coaxial with the first connection rod;

wherein the first ultrasonic transducer and first connection rod are interposed between the upper and lower portions, such that the first ultrasonic transducer is adapted to vibrate the upper and lower portions simultaneously.

15. The implantable medical device of claim 14 wherein the implantable medical device further comprises a second ultrasonic transducer coaxial with the first ultrasonic transducer and the first connection rod and interposed between the upper and lower portions.

16. The implantable medical device of claim 14 wherein the implantable medical device further comprises a second connection rod coaxial with the first ultrasonic transducer and the first connection rod and interposed between the upper and lower portions.

17. The implantable medical device of claim 14 wherein the implantable medical device further comprises a second connection rod and a second ultrasonic transducer coaxial with the first ultrasonic transducer and the first connection rod and interposed between the upper and lower portions.

18. The implantable medical device of claim 14 wherein the combined thickness of the first connection rod and the first ultrasonic transducer is between approximately 6 and 7 millimeters.

19. The implantable medical device of claim 14 wherein the first ultrasonic transducer comprises a lead zirconate titanate (PZT) material having a diameter of approximately 1 centimeter and a height of approximately 1 millimeter, the connection rod has a height of approximately 6 millimeters, a minimum diameter of approximately 1 centimeter, a maximum diameter of approximately 2.5 centimeters, and a taper beginning at a height of approximately 3 millimeters, and the thickness of the housing is between 0.3 to 2 millimeters and the width of the housing is between about 2.5 to 5 centimeters.

20. A method of optimizing an ultrasonic transducer and a housing of an implantable medical device, the method comprising:

determining system level requirements for the ultrasonic transducer;

selecting an initial ultrasonic transducer based on the system level requirements;

conducting a first finite element methods analysis to verify the feasibility of the initial ultrasonic transducer;

conducting a second finite element methods analysis and water tank experiments to determine whether the housing and ultrasonic transducer have a desired vibration mode at a targeted ultrasonic communication frequency;

optimizing the ultrasonic transducer or the design of the housing based on the results of the first and second finite element methods analysis and water tank experiments;

verifying a resonance frequency and amplitude of the optimized ultrasonic transducer using finite element method analysis and water tank experiments; and

selecting a final ultrasonic transducer and housing design based upon the results of the verifying step.

21. The method of claim 20 wherein the conducting a second finite element analysis and water tank experiments step includes at least one of the steps of conducting water tank experiments and scanning laser vibrometer (SLV) measurements.

22. The method of claim 20 wherein the verifying step includes includes at least one of the steps of conducting water tank experiments and scanning laser vibrometer (SLV) measurements.