Wireless charging device

Abstract

To provide a highly safe wireless charging device for an embedded-type medical apparatus.SOLUTION: A wireless charging device for supplying electric power to an embedded-type medical apparatus in a living body includes at least one electric power transmitter and at least one electric power receiver. The electric power transmitter is composed of two or more conductor flat plates, and the electric power receiver is composed of two or more conductor flat plates. The conductor flat plates of the electric power transmitter and the conductor flat plates of the electric power receiver are arranged mutually in parallel to skin. Surroundings of the conductor flat plates of the electric power transmitter is covered with an insulator.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power transmitter / receiver that transmits high-frequency power and a wireless charging device using the same, and more particularly to an electronic device and charging device for wirelessly supplying power to medical equipment and the like placed inside the human body or a living organism. [Background technology]

[0002] Conventional wireless charging devices for implantable medical devices transmit power using magnetic field coupling.

[0003] For example, Patent Document 1 discloses an implantable medical device including an implantable component with a rechargeable power source and an external wireless charger, the external wireless charger including a rechargeable power source and an inductive coil configured to transfer power through the skin, and configured to detect and receive power from an auxiliary charger for recharging the wireless charger.

[0004] The implantable medical devices described above transmit power using a high-frequency magnetic field, which allows for highly efficient power transmission and reception without being affected by the electrical conductivity or dielectric properties of the living body. However, the induction coil generates a leakage magnetic field. This leakage magnetic field can induce induced currents not only in the medical device itself, its circuits, and internal wiring, but also in external wiring connected to the device. Ferrite cores are typically used to prevent induced currents, but the size of the ferrite cores limits the feasibility of miniaturizing the medical device.

[0005] On the other hand, if countermeasures against induced currents are insufficient, medical devices are more likely to malfunction. Furthermore, when magnetic flux leaking from a microwave oven or other device intersects with the induction coil of an implantable medical device, unexpected induced currents can flow, destroying the rechargeable power supply or causing the induction coil to heat up, resulting in a sudden rise in temperature deep inside the body, posing significant safety issues. Patent Document 1 states that when transmitting approximately 3 W of power through magnetic field coupling at 300 kHz, the temperature deep inside the body will rise by approximately 4°C. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special publication 2014-500097 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the problems with the external wireless charger that uses the induction coil, and has an object to provide a highly safe wireless charging device for implantable medical devices. [Means for solving the problem]

[0008] The wireless charging device according to the present invention supplies power to an implantable medical device in a living body, At least one power transmitter and at least one power receiver are provided, The power transmitter is made up of two or more conductive flat plates, and the power receiver is made up of two or more conductive flat plates, the conductive plate of the power transmitter and the conductive plate of the power receiver are arranged parallel to and facing each other with respect to the skin, The conductor plate of the power transmitter is characterized in that its periphery is covered with an insulator.

[0009] The wireless charging device according to the present invention transmits power by using an electric field, so charging can be performed without being affected by the generation of induced current or leakage magnetic field.

[0010] Furthermore, simply by attaching the conductive plate of the power transmitter to the skin, power can be transmitted between the conductive plate of the power receiver and the power transmitter via an electric field. Note that the conductive plate of the power transmitter can be covered with an insulator without affecting power transmission, taking into account the effects on the skin and the use of medical equipment. [Effects of the Invention]

[0011] According to the present invention, in a medical device implanted in a living body, safe and highly efficient charging can be performed without causing equipment failure or an increase in temperature deep inside the body due to leakage magnetic fields caused by the use of an induction coil. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing an example of an environment in which an in-vivo wireless charging device according to the present invention is used; [Figure 2] 1 is a diagram illustrating the configuration of an in-vivo wireless charging device according to the present invention. [Figure 3] 1 is a block diagram showing an example of the configuration of an in-vivo wireless charging device according to the present invention. [Figure 4] FIG. 2 is a diagram showing an arrangement of a power transmitter and a power receiver according to an embodiment of the present invention. [Figure 5] 1 is a graph showing high-frequency characteristics of pig skin and subcutaneous tissue according to an embodiment of the present invention. [Figure 6] 10 is a graph showing power transmission efficiency characteristics between a power transmitter and a power receiver according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013]

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the drawings used in the description and the following description are provided for a thorough understanding of the present disclosure and are not intended to limit the subject matter described in the claims.

[0014] A wireless charging device according to the present invention will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of an environment in which a wireless charging device 1 according to the present invention is placed. An implantable medical device 3 is implanted in a human body 2. The implantable medical device 3 is equipped with a power receiver 200. The implantable medical device 3 may be, for example, a pacemaker, which sends electrical signals to provide a regular beat to the heart and also has electrical wiring 4 for acquiring biological information. The implantable medical device 3 is supplied with driving power wirelessly from a sheet-type power transmitter 5 placed outside the body.

[0015] The sheet-type power transmitter 5 is used by being attached to the skin, for example, as shown in Fig. 2. In this case, the sheet-type power transmitter 5 is composed of an adhesive film 6 for attaching to the skin, a circuit section 7 on which the power transmitter 100 is mounted, a power transmitting electrode 8 made of a metal flat plate, and an insulator 9. In this case, power is transmitted to the implantable medical device 3 via biological tissue 10 consisting of skin and subcutaneous fat. At this time, the implantable medical device 3 is composed of an insulator 11, a power receiving electrode 12 consisting of a metal flat plate, and a circuit section 13 on which a power receiver 200 is mounted. The insulators 9 and 11 are arranged to prevent metal corrosion due to direct contact with the human body and to ensure biocompatibility. For example, a coating of parylene polymer is used.

[0016] 3 is a block diagram showing an example configuration of a wireless charging device 5. The wireless charging device 5 includes a power transmitter 100, a power receiver 200, and a power transmitting electrode 8 and a power receiving electrode 12 each made of a flat metal plate. The power receiver 200 receives high-frequency power transmitted from the power transmitting electrode 8 mounted on the power transmitter 100 at the power receiving electrode 12. The power transmitting electrode 8 and the power receiving electrode 12 each have a structure in which at least two or more flat metal plates are arranged. The power transmitting electrode 8 and the power receiving electrode 12 are arranged in correspondence with each other with human tissue 10 interposed therebetween.

[0017] In such a state, for example, according to experimental data measured by Gabriel et al., when the human tissue 10 consists of skin and subcutaneous fat, it exhibits a Q value of 3.0 or more between 1.74 kHz and 30 kHz, and therefore, by setting the transmission frequency between 1.74 kHz and 30 kHz, it is possible to transmit power with high efficiency.

[0018] When considering miniaturization of the power transmitter and receiver, the Q value is 1.0 or more from around 200 MHz to 400 MHz, so power can be transmitted in a compact and highly efficient manner by setting the transmission frequency between 200 MHz and 400 MHz.

[0019] As a result, the implantable medical device 3 has at least two metal plates, and can receive power through electric field coupling simply by attaching the power transmission device 5 to the surface of the skin. This makes it possible to achieve highly efficient power supply of the required power from an external power transmitter using a simple device without significantly increasing the leakage magnetic field from outside the body, such as from the skin.

[0020] First, we will explain the sheet-type power transmitter 5. The sheet-type power transmitter 5 uses an external battery 101 as driving power and outputs high-frequency power from an RF power source 102. Since the power transmitting electrode 8 has a differential input, a matching circuit 103 and a balun 104 are connected to the input side of the power transmitting electrode 8 to convert a single-ended signal to a differential signal while achieving impedance matching with the output impedance of the RF power source 102. The external battery 101 is, for example, a film-type lithium battery, and the RF power source 102 and matching circuit 103 are, for example, configured on a flexible substrate made of polyimide. The RF power supply 101 may be designed as a differential output circuit. In this case, the matching circuit 103 is configured as a differential input / differential output, so that the balun 104 can be removed.

[0021] Next, the implantable medical device 3 will be described. High-frequency power transmitted from the power transmitting electrode 8 is received by the power receiving electrode 12. The power receiving electrode 12 is connected to a rectifier circuit 202 via a matching circuit 201, and converts the high-frequency power into DC power. The other end of the rectifier circuit 202 is connected to a battery 203, and DC power is input to charge the battery 203. The power of the charged battery 203 is supplied via a DC / DC converter 204 to, for example, a pacemaker 205. At this time, although not shown, by monitoring the amount of transmitted power of the received power, it is possible to automatically adjust the matching circuit 201 so that the amount of transmitted power increases. Note that by additionally connecting a DC / DC for charging the battery between the rectifier circuit 202 and the battery 203, the charging speed of the battery 203 can be increased.

[0022] In this way, power can be supplied from outside the body by a battery installed in the pacemaker. [Example]

[0023] The power transmitting electrode 8 shown in Fig. 2 is composed of two copper metal plates as shown in Fig. 4, which are designated as metal plate 14 and metal plate 15. Here, the insulator 9 of the sheet-type power transmitter 5 is represented by two insulator plates, which are designated as insulator plate 16 and insulator plate 17, and are made of FR4 (relative permittivity 4.7, dielectric loss tangent 0.01).

[0024] The thicknesses of the power transmitting electrode 8, which is a flat metal plate, and the insulator 9, which is a flat insulating plate, are 35 μm and 100 μm, respectively. The biological tissue 10 used here is pig skin and subcutaneous fat with a relative permittivity of 18 and a dielectric loss tangent of 0.77. The thickness is 5 mm.

[0025] The insulator 11 of the implantable medical device 3, like the insulator 9 on the power transmitter side, is represented by two insulator plates, designated insulator plate 18 and insulator plate 19, respectively, and made of FR4. The power receiving electrode 12, like the power transmitting electrode 8, is made by two copper metal plates, designated insulator plate 20 and metal plate 21, respectively.

[0026] The thicknesses of the power receiving electrode 12 made of a metal flat plate and the insulator 11 made of an insulating flat plate are set to 35 μm and 100 μm, respectively.

[0027] Conductor wiring 22, 23, 24, and 25 are connected to at least one side of each of the metal flat plates 14, 15, 20, and 21. The conductor wiring 22 and 23 are routed through holes in, for example, an adhesive film 6. In this example, the adhesive film 6 is a polyurethane dressing tape with a relative permittivity of 5.0 and a dielectric dissipation factor of 0.08. One end of the conductor wiring 22, 23, 24, and 25 is left open, and an SMA connector, for example, is soldered to this open end to connect wiring that supplies power.

[0028] The metal flat plates 14, 15, 20, 21 and the insulator flat plates 16, 17, 18, 19 have both long and short sides measuring 2 cm. The spacing between horizontally arranged metal flat plates 14 and 15, between metal flat plates 20 and 21, between insulator flat plates 16 and 17, and between insulator flat plates 18 and 19 is all 2 cm. The conductor wiring 22, 23, 24, 25 is approximately 3 cm long and 0.5 mm in diameter.

[0029] The measurement results of the relative permittivity and Q value of biological tissue 10 consisting of pig skin and subcutaneous fat are shown in Figure 5. The Q value is 1.0 or more from 200 MHz to around 400 MHz, and reaches a maximum value around 300 MHz.

[0030] In this example, the power transfer efficiency at around 300 MHz, where the Q factor is high, is shown in Figure 6. Figure 6 is a graph of the power transfer efficiency, calculated from the ratio of transmitted power to received power, plotted on the frequency axis, when an SMA connector fixed with solder and each terminal of a vector network analyzer are connected to one end of each of conductor wirings 22, 23, 24, and 25, and power transmitted from conductor wirings 22 and 23 connected to power transmitting electrode 8 is received by power receiving electrode 12 and extracted from conductor wirings 24 and 25.

[0031] Figure 6 shows that biological tissue 10 behaves as a dielectric in the high-frequency band. Metal plates 14, 15, 20, and 21 form a capacitor with biological tissue 10, and power is transmitted by electric field coupling. As a result, a simple device can be used to efficiently supply the necessary power from an external power transmitter without significantly increasing the leakage magnetic field from outside the body, such as the skin. Furthermore, because power transmitter 5 can be realized with such a thin thickness, it can be attached with good adhesion according to the curvature of the skin, allowing implantable medical device 3 to be charged without interfering with daily life or during sleep.

[0032] In this example, for ease of experimentation, conductor wiring 22, 23 is provided as the power input line, and conductor wiring 24, 25 is provided as the power output line, but this does not necessarily have to be the case, and for example, the power input line and output line may be provided by providing via holes on the metal plates 14, 15 and the metal plates 20, 21. This can reduce loss due to the wiring lines.

[0033] Alternatively, although not shown, the circuit section 7 on which the power transmitter 100 is mounted can be made of a dielectric film substrate, and the circuit section 13 on which the power receiver 200 is mounted can be made of a dielectric substrate, and electric power can be input and output by electric field coupling by providing metal flat plates 14, 15 and metal flat plates 20, 21 facing each other via a dielectric film substrate or a dielectric substrate. This eliminates the need for via holes and makes production easier.

[0034] In this example, the dressing tape was used on the adhesive film 6 for ease of experimentation, but this is not necessarily the case. For example, an adhesive material may be used for the insulators 16 and 17 that cover the metal plates 14 and 15. This minimizes the contact area with the skin and reduces the impact of the adhesive on the skin.

[0035] In this example, rectangular metal plates 14, 15, 20, 21 and insulating plates 16, 17, 18, 19 were used for ease of experimentation, but this does not necessarily apply. Metal plates with a shape that reduces electric field coupling between adjacent metal plates, such as a circular or home plate-shaped plate, may be used. This reduces electric field coupling between adjacent metal plates, improving power transmission efficiency. Furthermore, the insulator plate may have a flat plate structure or a thin film structure that covers the entire metal plate electrode. This prevents direct contact between the metal plate and the skin, preventing metal corrosion, etc.

[0036] In this example, for ease of experimentation, rectangular metal flat plates 14, 15, 20, 21 having the same area are used for the power transmitting electrode 8 and the power receiving electrode 12, but this is not necessarily the case. To ensure compatibility even if the transmitting and receiving electrodes are misaligned, the area of ​​the transmitting electrode is made larger than that of the receiving electrode. For example, by making the area 1.1 times larger, the transmitting electrode will be 2.2cm square compared to the 2cm square receiving electrode. Therefore, even if the transmitting and receiving electrodes are misaligned by 0.2cm in either the long or short direction, the opposing area of ​​the transmitting and receiving electrodes can be maintained at 2cm x 2cm, preventing a decrease in efficiency. [Explanation of symbols]

[0037] 1 Wireless charging device 2 human body 3 Implantable medical devices 4 Electrical wiring 5. Sheet-type power transmitter 6. Adhesive film 7 Circuit unit equipped with power transmitter 100 8. Power transmission electrode 9, 11 Insulators 10 Biological tissue 12. Receiving electrode 13 Circuit unit on which the power receiver 200 is mounted 14, 15, 20, 21 Metal flat plate 16, 17, 18, 19 Insulator plates 22, 23, 24, 25 Conductor wiring 100 Power Transmitter 101 External Battery 102 RF power supply 103, 203 matching circuit 104 Balun 200 Power receiver 201 Matching circuit 202 Rectifier circuit 203 Battery 204 DC / DC 205 Pacemaker

Claims

1. A wireless charging device for supplying power to an implantable medical device in a living body, An RF power source with a transmission frequency of 200 MHz to 400 MHz; a power transmission circuit section; At least one power transmitter, which is connected to the power transmitting side circuit unit and is composed of two or more conductor flat plates; a power receiving side circuit unit; At least one power receiver, which is connected to the power receiving side circuit section and is made up of two or more conductor flat plates, the conductive plate of the power transmitter and the conductive plate of the power receiver are arranged parallel to and facing each other with respect to biological tissue, Furthermore, the conductive plate of the power transmitter is covered with an insulator and has an area larger than the area of ​​the conductive plate of the power receiver.

2. 2. The wireless charging device according to claim 1, wherein the conductor plate of the power receiver is covered with an insulator.

3. 3. The wireless charging device according to claim 1, wherein the conductive plate of the power transmitter has an area 1.1 times the area of ​​the conductive plate of the power receiver.

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