Method and apparatus for supplying energy to a medical device

• US 8,463,394 B2
• Filed: 10/10/2008
• Issued: 06/11/2013
• Est. Priority Date: 10/16/2007
• Status: Active Grant

• Current Assignee: Kirk Promotion Ltd.
• Original Assignee: Teslux Holding SA
• Inventors: Forsell, Peter
• Primary Examiner(s): Koharski, Christopher D
• Assistant Examiner(s): EDWARDS, PHILIP CHARLES
• Application Number:
  US12/682,831
• Publication Number:
  US 20100222848A1
• Time in Patent Office: 1,705 Days
• Field of Search: 607/61
• US Class Current: 607/61
• CPC Class Codes: A61F 2250/0001 Means for transferring electromagnetic energy to implants
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H02J 2310/23 The load being a medical device, a medical implant, or a life supporting device
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge

Abstract

In a method and apparatus for supplying wireless energy to a medical device (100) implanted in a patient, wireless energy is transmitted from an external energy source (104) located outside a patient and is received by an internal energy receiver (102) located inside the patient, for directly or indirectly supplying received energy to the medical device. An energy balance is determined between the energy sent by the external energy source and energy received by the internal energy receiver, and the transmission of wireless energy is then controlled based on the determined energy balance. The energy balance thus provides an accurate indication of the correct amount of energy needed, which is sufficient to operate the medical device properly, but without causing undue temperature rise.

Claims

1. A method for controlling transmission of wireless energy supplied to an electrically operable medical device implanted in a mammal patient, the method comprising the steps of:

transmitting wireless energy from an external energy source by means of a primary coil located outside the patient, and

receiving the transmitted wireless energy inductively in an internal energy receiver by means of a secondary coil located inside the patient, to directly or indirectly supply received energy to the medical device,

receiving by an electronic circuit in the external energy source feedback information sent from inside the patient,

comparing the feedback information with the amount of energy transmitted by the external energy source, wherein the feedback information is related to the amount of energy being received in the internal energy receiver,

analysing by an analyzer in the electronic circuit the amount of energy being transmitted,

using the received feedback information related to the amount of energy received in the internal energy receiver,

determining a special energy balance by comparing the amount of transmitted energy and the feedback information related to the amount of received information, thus the feedback information is related to a coupling factor between the primary coil and the secondary coil,

obtaining information about the coupling factor between the coils,

calibrating the system for;

a) finding an optimal place for the external coil in relation to the internal coil, and

b) optimizing energy transfer, comparing the amount of energy transferred with the amount of energy received,

detecting an energy balance after said calibration of the special energy balance being at least one of;

a difference between the total amount of energy received by the internal energy receiver and the total amount of consumed and stored energy, being directly or indirectly measured over time, and

an energy reception rate in the internal energy receiver corresponding to the total rate of energy consumption and storage of the apparatus,

determining the energy balance based on at least one of;

a detected change in the difference in the total amount of energy received by the internal energy receiver and the total amount of consumed and stored energy, and

a detected change in the difference between the energy reception rate in the internal energy receiver and the total rate of energy consumption and storage,

controlling the transmission of wireless energy from the external energy source, based on the determined energy balance to optimize energy transfer, during energy transfer.

2. The method according to claim 1, the method further comprising at least one of:

consuming the energy after being stabilized in the at least one energy stabilizing unit of the medical device, and

accumulating and stabilizing the energy received by the internal energy receiver in the at least one energy stabilizing unit, before the energy is supplied to the medical device.

3. The method according to claim 1, further comprising the step of stabilizing the energy received by the internal energy receiver by a capacitor, before the energy is supplied directly or indirectly to the medical device.

4. The method according to claim 1, further comprising the step of indicating by an indicator in the external energy source at least one of:

a level of the coupling factor, and

an optimal placement of said secondary coil in relation to said primary coil to optimize said coupling factor.

5. The method according to claim 1, further comprising the step of receiving the energy by the internal energy receiver being supplied to the medical device with at least one of:

at least one constant voltage, wherein the constant voltage is created by a constant voltage circuitry, preferably the energy being supplied with at least two different voltages, including the at least one constant voltage, and

at least one constant current, wherein the constant current is created by a constant current circuitry, preferably the energy being supplied with at least two different currents including the at least one constant current.

6. The method according to claim 1, further comprising the step of determining the energy balance based on a detected difference between the total amount of energy received by the internal energy receiver and the total amount of consumed and stored energy, the detected difference being related to the integral over time of at least one measured electrical parameter related to the energy balance.

7. The method according to claim 1, wherein the medical device comprises an energy storage device, comprising at least one of;

a rechargeable battery, an accumulator and a capacitor.

8. The method according to claim 1, further comprising the steps of:

accumulating and stabilizing the energy received by the internal energy receiver in at least one of;

an energy stabilizing unit before the energy is supplied to the medical device, and

an energy storage device, and

supplying the energy to at least one of;

the medical device, and

the energy storage device,

supplying with at least one constant voltage, at least one constant current or at least one constant current and at least one constant voltage, as maintained by a constant voltage circuitry, constant current circuitry or one constant voltage and constant current circuitry, when at least one of;

the medical device and energy storage device is supplied with two different voltages or currents, at least one voltage or current is constant, maintained by the constant voltage or current circuitry.

9. The method according to claim 2, further comprising the step of determining the energy balance by detecting at least one of:

a change in the current amount of accumulated energy in the energy stabilizing unit,

the direction and rate of change in the current amount of accumulated energy in the energy stabilizing unit,

a change in the current amount of accumulated energy in the energy stabilizing unit,

the direction and rate of change in the current amount of accumulated energy in the energy stabilizing unit.

10. The method according to claim 8, further comprising the step of determining the energy balance by detecting at least one of:

a change in the current amount of accumulated energy in the energy stabilizing unit,

the direction and rate of change in the current amount of accumulated energy in the energy stabilizing unit,

a change in the current amount of accumulated energy in the energy stabilizing unit,

the direction and rate of change in the current amount of accumulated energy in the energy stabilizing unit.

11. The method according to claim 1, further comprising the step of using sensors for at least one of:

measuring characteristics of the medical device,

detecting the current condition of the patient, and

reflecting the required amount of energy needed for proper operation of the medical device,

determining at least one of;

electrical parameters, physical parameters or electrical and physical parameters of the medical device, and

physical parameters of the patient, and

transmitting the energy with a transmission rate which is determined based on the parameters.

12. The method according to claim 9, comprising sensors for at least one of:

measuring characteristics of the medical device,

detecting the current condition of the patient, and

reflecting the required amount of energy needed for proper operation of the medical device,

determining at least one of;

electrical parameters, physical parameters or electrical and physical parameters of the medical device, and

physical parameters of the patient, and

transmitting the energy with a transmission rate which is determined based on the parameters.

13. The method according to claim 7, wherein the energy storage device of the medical device comprises a first storage device and a second storage device, and wherein the method further comprises the steps of:

storing the energy received by the internal energy receiver first in the first storage device, and then supplying the energy from the first storage device to the second storage device at a later stage,

determining the energy balance by detecting at least one of;

the current amount of energy stored in the first storage device, wherein the transmission of wireless energy being controlled such that a storing rate in the second storage device corresponds to an energy reception rate in the internal energy receiver,

the total amount of stored energy in the first storage device,

a change in the current amount of stored energy in the first storage device, or

a direction and rate of change in the current amount of stored energy in the first storage device.

14. The method according to claim 13, further comprising the step of using a constant current circuitry for supplying stabilized energy from the first storage device to the second storage device with a constant current until a measured voltage over the second storage device reaches a predetermined maximum voltage, and thereafter supplied from the first storage device to the second storage energy storage device with a constant voltage, as maintained by a constant voltage circuitry, so the transmission of wireless energy can be turned off when a predetermined minimum rate of transmitted energy has been reached.

15. The method according to claim 1, comprising the step of using an internal control unit and an implantable switch for executing an on and off switching of the secondary coil as being controlled by the internal control unit.

16. The method according to claim 13, wherein the first storage device is involved in at least one of the following steps:

being charged at a relatively higher energy charging rate as compared to the second storage device, thereby enabling a relatively faster charging, and

being charged at multiple individual charging occasions more frequently as compared to the second storage device, thereby providing relatively greater life-time in terms of charging occasions.

17. The method according to claim 1, further comprising the step of detecting a change in said difference, the change in the amount of consumed energy is detected by determining over time the derivative of a measured electrical parameter related to the amount of consumed energy, the derivative corresponding to the rate of the change in the amount of consumed energy, wherein the rate of change includes the direction and speed of the change, wherein a rate of change of the electrical parameter is detected, the derivative being related to the detected change rate.

18. The method according to claim 9, further comprising the step of detecting a change in said difference, the change in the amount of consumed energy is detected by determining over time the derivative of a measured electrical parameter related to the amount of consumed energy, the derivative corresponding to the rate of the change in the amount of consumed energy, wherein the rate of change includes the direction and speed of the change, wherein a rate of change of the electrical parameter is detected, the derivative being related to the detected change rate.

19. The method according to claim 6, further comprising the step of detecting the difference related to the integral over time of at least one measured electrical parameter related to said energy balance, the integral may be determined for a monitored voltage, current or voltage and current related to the energy balance.

20. The method according to claim 11, further comprising the steps of:

determining at least one of;

electrical, parameters, physical parameters or electrical and physical parameters of the medical device, and

physical parameters of the patient, and

transmitting the wireless energy for at least one of;

consumption and storage, according to a transmission rate per time unit which is determined based on said parameters.

21. The method according to claim 11, further comprising the step of:

determining for energy storage at least one of;

electrical parameters, physical parameters or electrical and physical parameters of the medical device, and

physical parameters of the patient, and

turning off the transmission of wireless energy automatically when a total amount of energy has been stored, controlling the transmission of wireless energy such that an energy reception rate at the internal energy receiver corresponds to the storing rate.