Resonator with adjustable capacitor for medical device

• US 20070062933A1
• Filed: 08/23/2005
• Published: 03/22/2007
• Est. Priority Date: 08/23/2005
• Status: Active Grant

• Current Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Original Assignee: Boston Scientific Scimed (Boston Scientific Corporation)
• Inventors: Weber, Jan
• Granted Patent: US 7,304,277 B2
• Time in Patent Office: Days
• US Class Current: 219/674
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61F 2/82 Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents stent-grafts for tubular structures of the body other than blood vessels A61F2/04; stent-grafts for blood vessels A61F2/07; instruments specially adapted for placement or removal of stents or stent-grafts A61F2/95; for closing wounds, or holding wounds closed A61B17/04 - A61B17/115; dilators A61M29/00
• CPC Class Codes: G01R 33/286 involving passive visualization of interventional instruments, i.e. making the instrument visible as part of the normal MR process
• CPC Class Codes: G01R 33/3628 Tuning/matching of the transmit/receive coil
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing

Abstract

An apparatus, system and method of a resonator device with an adjustable capacitor for allowing the resonance frequency (F) of the resonator device to continue to be matched to the Larmor frequency of the MRI system. The resonator device includes an inductor coil, a conductive member, a sleeve having first and second sockets that receive at least portions of the inductor coil and the conductive member as electrodes to provide a capacitor structure. Dielectric material can be positioned between at least the first and second sockets, where changes in the cross sectional area defined by the induction coil cause changes in the capacitance value (C) as one or more of the electrodes move within the socket. Changes in the inductance and the capacitance values allow for the resonance frequency (F) of the resonator device to continue to be matched to the Larmor frequency of the MRI system.

Claims

1. A resonator device, comprising:

an inductor coil;

a conductive member that extends from the inductor coil;

a sleeve that includes surfaces defining a first socket and a second socket, a dielectric material between the first and second sockets and a portion of the induction coil within the first socket and a portion of the conductive member within the second socket to form a capacitor structure.

2. The resonator device of claim 1, where the dielectric material between the first and second sockets tapers between a first end of the sleeve and a second end of the sleeve.

3. The resonator device of claim 1, where a capacitance value (C) of the capacitor structure changes when the portion of at least one of the induction coil and the conductive member changes position when the induction coil expands from a first circumference to a second circumference.

4. The resonator device of claim 1, including a second capacitor in series between the first end of the inductor coil and the second end of the conductive member.

5. The resonator device of claim 1, where the sleeve of dielectric material is a flexible polymeric material.

6. The resonator device of claim 1, including a resistor in series with the inductor coil, the conductive member and the capacitor structure.

7. A resonator device, comprising:

an inductor coil that includes a first end;

a conductive member that extends from the inductor coil, the conductive member positioned adjacent the inductor coil and includes a second end; and

a sleeve of dielectric material that includes surfaces defining a first socket and a second socket, where the first end of the inductor coil passes into the first socket and the second end of the conductor member passes into the second socket adjacent the first end to form a capacitor structure.

8. The resonator device of claim 7, where the first socket extends from a first end of the sleeve and the second socket extends from a second end of the sleeve, and where a distance between the first socket and the second socket taken perpendicular to a longitudinal axis of the sleeve changes in a predetermined fashion between the first end and the second end of the sleeve.

9. The resonator device of claim 8, where the distance between the first socket and the second socket adjacent the fist end is greater than the distance between the first socket and the second socket adjacent the second end.

10. The resonator device of claim 8, where the sleeve has an exterior surface that tapers between the first end and the second end.

11. The resonator device of claim 8, where the predetermined fashion is a linear function d₁=α

l+d₂, where d₁ is the distance between the first socket and the second socket adjacent the fist end, d₂ is the distance between the first socket and the second socket adjacent the second end, l is a distance that at least one of the first end and the second end move within the first socket and the second socket of the sleeve of dielectric material, and α

is a rate of change along the longitudinal axis of the sleeve.

12. The resonator device of claim 8, where the first end and the second end are in a first position when the induction coil has a first circumference and in a second position when the induction coil has a second circumference that is greater than the first circumference.

13. The resonator device of claim 12, where a capacitance value (C) of the capacitor structure has a first value when the first end and the second end are in the first position and a second valve different than the first value when the first end and the second end are in the second position.

14. The resonator device of claim 7, where the induction coil includes a circumference that increases from a first size to a second size that is larger than the first size as at least one of the first end and the second end move within the first socket and the second socket of the sleeve of dielectric material.

15. The resonator device of claim 14, where a capacitance value of the capacitor structure changes as at least one of the first end and the second end move in the first socket and the second socket.

16. A method of maintaining a resonance frequency of a resonator device, comprising:

changing a circumference of an inductor coil of the resonator device to change an inductance (L) of the resonator device; and

proportionally changing a capacitance (C) of a capacitor of the resonator device as the circumference of the induction coil changes to maintain the resonance frequency of the resonator device.

17. The method of claim 16, where proportionally changing a capacitance of a capacitor of the resonator device as the circumference of the induction coil changes includes increasing the circumference of the inductor coil and proportionally decreasing the capacitance of the capacitor as the circumference increases.

18. The method of claim 17, where proportionally changing a capacitance (C) of a capacitor of the resonator device includes changing a position of a portion of the inductor coil adjacent a dielectric material relative a portion of a conductive member that couples the resonator device in series.

19. The method of claim 16, where proportionally changing a capacitance (C) of a capacitor of the resonator device includes changing the capacitance (C) based on a linear function.

20. The method of claim 16, where proportionally changing a capacitance (C) of a capacitor including tapering at least a portion of a dielectric material of the capacitor across which at least one electrodes of the capacitor pass.