MRI-safe implant electronics

• US 9,008,792 B2
• Filed: 08/17/2010
• Issued: 04/14/2015
• Est. Priority Date: 08/20/2009
• Status: Active Grant

• Current Assignee: Med El Elektromedizinische Geraete GmbH
• Original Assignee: Med El Elektromedizinische Geraete GmbH
• Inventors: Zimmerling, Martin, Baumgartner, Josef
• Primary Examiner(s): Porter, Jr., Allen
• Application Number:
  US12/857,848
• Publication Number:
  US 20110043210A1
• Time in Patent Office: 1,701 Days
• Field of Search: 607/33, 607/61, 607/63
• US Class Current: 607/63
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61N 1/0541 Cochlear electrodes
• CPC Class Codes: A61N 1/086 Magnetic resonance imaging [MRI] compatible leads
• CPC Class Codes: A61N 1/3718 Monitoring of or protection against external electromagnetic fields or currents
• CPC Class Codes: A61N 1/378 Electrical supply
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: G01R 33/285 Invasive instruments, e.g. catheters or biopsy needles, specially adapted for tracking, guiding or visualization by NMR
• CPC Class Codes: G01R 33/288 Provisions within MR facilities for enhancing safety during MR, e.g. reduction of the specific absorption rate [SAR], detection of ferromagnetic objects in the scanner room
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H04R 2225/49 Reducing the effects of electromagnetic noise on the functioning of hearing aids, by, e.g. shielding, signal processing adaptation, selective (de)activation of electronic parts in hearing aid
• CPC Class Codes: H04R 2225/67 Implantable hearing aids or parts thereof not covered by H04R25/606

Abstract

A power supply arrangement for an implantable electronic system is described. An MRI power supply arrangement cooperates with an implantable power supply circuit to provide a high output impedance for implanted circuitry during magnetic resonance imaging (MRI).

Claims

1. A power supply arrangement for an implantable electronic system comprising:

a main implant power supply comprising;

i. an implant receiver coil L₁₀₁ and a parallel capacitor C₁₀₁ arranged to form a resonant circuit that receives an externally generated RF signal,

ii. a Schottky diode D₁₀₁ in series with the L₁₀₁/C₁₀₁ resonant circuit and configured to rectify the RF signal received by the L₁₀₁/C₁₀₁ resonant circuit, and

iii. a power supply output circuit comprising an output capacitor C₁₀₂ in parallel with an overvoltage Zener diode D₁₀₂, the power supply output circuit being arranged in parallel with the Schottky diode D₁₀₁ and the L₁₀₁/C₁₀₁ resonant circuit to receive the rectified RF signal from the Schottky diode D₁₀₁ and develop a main implant power supply voltage output during normal operation of the implantable electronic system; and

an implantable magnetic resonance imaging (MRI) power supply arrangement comprising;

i. an MRI inductance L₁₀₂ configured to have broad-band inductive coupling characteristics to sense RF pulses from MR scanner fields during MRI, and

ii. an MRI rectifier diode D₁₀₃ in series with the MRI inductance L₁₀₂ and arranged to rectify the RF pulses sensed by the MRI inductance L₁₀₂ during MRI;

wherein the MRI power supply arrangement is arranged in parallel with the power supply output circuit and in parallel with the Schottky diode D₁₀₁ and the L₁₀₁/C₁₀₁ resonant circuit so as to cooperate with the main implant power supply to provide a high impedance state power supply voltage output during MRI.

2. A power supply arrangement according to claim 1, wherein the implanted circuitry is for a cochlear implant system.

3. A method for providing electrical power to an implantable electronic system, the method comprising:

providing a main implant power supply voltage during normal operation of the implantable electronic system from a main implant power supply comprising;

i. an implant receiver coil L₁₀₁ and a parallel capacitor C₁₀₁ arranged to form a resonant circuit that receives an externally generated RF signal, and

ii. a Schottky diode D₁₀₁ in series with the L₁₀₁/C₁₀₁ resonant circuit and configured to rectify the RF signal received by the L₁₀₁/C₁₀₁ resonant circuit, and

iii. a power supply output circuit comprising an output capacitor C₁₀₂ in parallel with an overvoltage Zener diode D₁₀₂, the power supply output circuit being arranged in parallel with the Schottky diode D₁₀₁ and the L₁₀₁/C₁₀₁ resonant circuit to receive the rectified RF signal from the Schottky diode D₁₀₁ and develop a main implant power supply voltage output during normal operation of the implantable electronic system,

providing a high impedance state power supply voltage output during magnetic resonance imaging (MRI) from an implantable MRI power supply arrangement comprising;

i. an MRI inductance L₁₀₂ configured to have broad-band inductive coupling characteristics to sense RF pulses from MR scanner fields during MRI, and

ii. an MRI rectifier diode D₁₀₃ in series with the MRI inductance L₁₀₂ and arranged to rectify the RF pulses sensed by the MRI inductance L₁₀₂ during MRI, wherein the MRI power supply arrangement is arranged in parallel with the power supply output circuit and in parallel with the Schottky diode D₁₀₁ and the L₁₀₁/C₁₀₁ resonant circuit so as to cooperate with the main implant power supply to provide the high impedance state power supply voltage output during MRI.

4. A method according to claim 3, wherein the implanted circuitry is for a cochlear implant system.