DE202021104268U1 - Impedance tomography system for the alignment feedback of a charger for an implantable medical device - Google Patents

Abstract

Medical system (1), comprising:
- An implantable medical device (2) having an energy store for supplying the medical device (2) with electrical energy and a secondary coil (20) for transferring electrical energy to the energy store,
- A charger (3) which is designed to charge the energy store, the charger having a primary coil (30) via which electrical energy can be transferred to the energy store via the secondary coil (20) of the implantable medical device (2), characterized , that
the charger (3) has a plurality of metal electrodes (31) which are arranged in front of the primary coil (30) and are each assigned to a segment (32) of a housing surface (33) of the charger (3), the charger (3) for this purpose is designed to use the metal electrodes (31) to calculate an impedance for each segment (32) and to use the impedances to check whether the primary coil (30) is aligned with the secondary coil (20) for optimum energy transfer.

Description

The present invention relates to a medical system with an implantable medical device and an external charger for charging an energy store of the medical device, for example in the form of an implantable pulse generator (IPG).

In a receiver for a resonant inductive system for wireless energy transmission (WPT) there is a coil on the charger that excites a coil on the implantable medical device. The alignment of the coils on the charger and the implantable medical device is critical to highly efficient energy transfer. Efficient energy transfer enables less thermal stress on the patient and potentially faster charging times. Alignment feedback is also important for the patient to quickly align the charger over the implantable or implanted medical device (in some cases in awkward locations such as the back).

One way to determine the orientation is to identify the conductive metallic titanium housings that are typically used in implants (pacemakers, neurostimulators).

Impedance tomography is a technique that measures the impedance of a target object and uses this to infer the composition or presence of a material. Impedance measurements consist of an arrangement of electrodes (at least two) on which an alternating current is output and the corresponding voltage is measured. According to Ohm's law, the impedance is Z = V / I, where V is the measured complex voltage and I is the injected complex current. Complex refers to the ohmic and reactive components of the impedance. Based on the medium in which the current is flowing, the impedance changes. Impedance tomography is sensitive to electrical conductivity. Larger electrode arrays enable a finer resolution of the image.

In the prior art, arrays of magnetic field sensor coils are known, which are located on the coil of the charger. When the charger is over a metal target, the magnetic field sensor coils change amplitude. Detection of the primary coil of the charger (metal detector mode) is also known. The presence of backscatter (e.g. LSK) can also be detected.

Furthermore, the US 2018/0212451 A1 charging an energy source located in an implantable medical device implanted in a patient, the charging device comprising first and second pairs of electrical coils configured to generate first and second uniform magnetic fields in overlapping first and second create cylindrical areas located between the respective pairs of electrical coils.

Furthermore, the WO 2019/173866 A1 an apparatus for providing sensory stimulation to a subject, the apparatus comprising a coil system having at least one coil and an electronic controller that operates in accordance with software instructions. In use, the controller receives input signals, performs an analysis of the input signals, and uses the results of the analysis to cause a signal generator to generate stimulation signals, the stimulation signals being applied to the coil system to thereby create a stimulating electromagnetic field in a target region of the subject to create.

Proceeding from the prior art set out above, the present invention is based on the object of implementing a means that gives a patient who is trying to position an external charger over his implant fast alignment feedback for optimal and efficient energy transfer.

This object is achieved by a medical system with the features of claim 1. Advantageous embodiments of the invention are described below.

• - ein implantierbares medizinisches Gerät aufweisend einen Energiespeicher (z.B. in Form einer Batterie) zur Versorgung des medizinischen Geräts mit elektrischer Energie sowie eine Sekundärspule zum Übertragen von elektrischer Energie auf den Energiespeicher, und
• - ein externes bzw. separates Ladegerät, das zum Aufladen des Energiespeichers ausgebildet ist, wobei das Ladegerät eine Primärspule aufweist, über die elektrische Energie über die Sekundärspule des implantierbaren Geräts auf den Energiespeicher übertragbar ist.

According to claim 1, a medical system is disclosed, comprising:

• an implantable medical device having an energy store (eg in the form of a battery) for supplying the medical device with electrical energy and a secondary coil for transferring electrical energy to the energy store, and
• an external or separate charger which is designed to charge the energy store, the charger having a primary coil via which electrical energy can be transmitted to the energy store via the secondary coil of the implantable device.

According to the invention it is provided that the charger has a plurality of metal electrodes which are arranged in front of the primary coil and are each assigned to a segment of a housing surface of the charger, the Segments form a two-dimensional field or array, and the charger is designed to calculate an impedance for each segment with the help of the metal electrodes in order to check whether the primary coil is aligned with the secondary coil for optimal energy transfer, ie, this in particular coaxially opposite.

The system according to the invention thus enables the position of the implanted medical device to be recognized and thus enables the charger to provide the patient with an alignment feedback (direction and approximate distance). The invention thus promotes efficient energy transfer from the charger to the implant. In other words, the charger has an impedance tomography function to identify the position of the implant (e.g. IPG) and then to give the user feedback on the alignment between the coils on both sides.

• 1 eine Gehäuseoberfläche eines Ladegeräts eines erfindungsgemäßen Systems, wobei die Gehäuseoberfläche ein Feld aus Segmenten aufweist, wobei jedem Segment eine Metallelektrode zugeordnet ist, die vor einer Primärspule des Ladegeräts angeordnet sind,
• 2 eine schematische Schnittansicht des Ladegeräts und des implantierbaren medizinischen Geräts (das in einen Patienten implantiert ist), wobei die Metallelektroden an der Gehäuseoberfläche die Hautoberfläche des Patienten kontaktieren,
• 3 zeigt die Segmente der Gehäuseoberfläche, wobei hier noch keine optimale Ausrichtung des Ladegeräts vorliegt, da die Achsen der Primär- und Sekundärspule nicht zusammenfallen, und
• 4 zeigt ein optimale Ausrichtung des Ladegeräts mit zusammenfallenden Spulenachsen der Primär- und Sekundärspule.

In the following, embodiments of the present invention and further features and advantages of the invention are to be explained with reference to the figures. Show it:

• 1 a housing surface of a charger of a system according to the invention, the housing surface having an array of segments, each segment being assigned a metal electrode which is arranged in front of a primary coil of the charger,
• 2 a schematic sectional view of the charger and the implantable medical device (which is implanted in a patient), wherein the metal electrodes on the housing surface contact the skin surface of the patient,
• 3 shows the segments of the housing surface, whereby the charger is not yet optimally aligned because the axes of the primary and secondary coils do not coincide, and
• 4th shows an optimal alignment of the charger with coinciding coil axes of the primary and secondary coils.

1 shows related to 2 a medical system according to the invention 1 with a wireless energy transmission system (WPT), having an external charger 3 and an implantable medical device 2 (e.g. IPG), with the charger 3 a primary coil 30th contains, and wherein the implantable medical device 2 that according to 2 implanted in a patient P is a secondary coil 20th contains.

The charger 3 has at least two metal electrodes close to the body 31 which are intended to touch the skin of the patient P. The electrodes 31 are on a housing surface 33 of the charger 3 arranged. The housing surface 33 can also be formed by a flat substrate (eg patch or plaster) that connects to the rest of the charger 3 is suitably connected.

The charger 3 is according to 2 designed to generate an alternating current I in the metal electrodes 31 to induce the charger 3 measures the corresponding AC voltage V induced by this current. The charger 3 uses this to calculate the complex impedance (Z = V / I) for at least four segments 32 or here for everyone in the 3 and 4th segments shown 32 the housing surface 33 Use these pictures to show the impedances in each segment 32 and those for different orientations of the coils on both sides 20th , 30th in the 3 and 4th are shown by way of example, the presence of conductors and non-conductors is distinguished on the basis of the impedances, so that the alignment of the coils can be determined 20th , 30th is possible to each other. Preferably the charger is 3 designed to provide user feedback for the purpose of aligning the charger 3 or the primary coil 30th above the metallic implant 2 or its secondary coil 20th to spend. The user feedback can take place, for example, via a handheld remote control, via warning tones or the like.

the 3 shows an example of an impedance diagram that is obtained by calculating the impedances for the segments 32 results. In the 3 is the axis Z 'of the secondary coil 20th too far up and to the right of the center or axis Z of the primary coil 30th removed.

After the alignment feedback from the charger 3 to the patient P and the patient movement of the charger 3 the positioning for optimal alignment changes accordingly 4th , in which the coil axes Z, Z 'coincide.

Another embodiment of the invention has a charger with multiple primary coils in an array. Impedance tomography is used to determine which coil is optimal for activation in order to achieve high power transfer efficiency. This is the opposite of the single primary coil that moves to find the implant; here the correct coil is selected electronically.

The invention allows reliable identification of the implant 2 compared to other methods that use multiple sense / search coils to look for disturbances in the excitation field. Impedance tomography can also prove useful for other reasons (e.g. for Determination of the tissue reaction to the implant, particularly inflammation, scar tissue, etc.).

It will be apparent to those skilled in the art that numerous modifications and variations of the examples and embodiments described are possible in light of the above teaching. The disclosed examples and embodiments are presented for the purpose of illustration only. Other alternative embodiments may include some or all of the features disclosed herein. Therefore, it is intended to cover all such modifications and alternative embodiments that may come within the true scope of this invention.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• US 2018/0212451 A1 [0006]
• WO 2019/173866 A1 [0007]

Claims (1)

Medical system (1), comprising: - an implantable medical device (2) having an energy store for supplying the medical device (2) with electrical energy and a secondary coil (20) for transferring electrical energy to the energy store, - a charger (3 ), which is designed to charge the energy store, the charger having a primary coil (30) via which electrical energy can be transferred to the energy store via the secondary coil (20) of the implantable medical device (2), characterized in that the charger ( 3) has a plurality of metal electrodes (31) which are arranged in front of the primary coil (30) and are each assigned to a segment (32) of a housing surface (33) of the charger (3), the charger (3) being designed to using the metal electrodes (31) to calculate an impedance for each segment (32) and to use the impedances to check whether the primary coil (30) is at the optimum level Energy transmission is aligned on the secondary coil (20).

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