KR20190100765A - Implantable medical device - Google Patents

Abstract

The present invention relates to an in vivo implantation type medical device comprising: a power reception unit receiving power transmitted from an in vitro power transmitter in a wireless power transmission type using ultrasonic wave; a battery storing the power received through the power reception unit; a case formed in a box shape with an opened upper surface and forming appearance; and a matching layer packaging the upper surface of the case and matching acoustic impedance of an ultrasonic signal transferred from the power transmitter through a medium layer. The power reception unit is formed with an ultrasonic transducer converting the ultrasonic signal transferred from the power transmitter into electric energy and the matching layer is coupled to the power reception unit to form a piezoelectric complex body. Accordingly, the power can be transmitted to a medical device implanted in a human body in the wireless power transmission type using the ultrasonic wave. Moreover, the matching layer matching the acoustic impedance is formed in a space between piezoelectric elements forming an array-structure transducer and an upper part thereof to minimize reflective loss of the transmitted power, thereby increasing wireless power transmission efficiency.

Description

Implantable medical device {IMPLANTABLE MEDICAL DEVICE}

The present invention relates to an implantable medical device, and more particularly, to an implantable medical device for wirelessly transmitting power to an internal device of a medical device to be implanted in the body.

Recently, artificial organs such as pacemakers, cochlear implants, gastric stimulators, spinal cord stimulators, cardiac defibrillators, cardiac pacemakers, insulin pumps, foot drop implants, and deep brains are used to alleviate or treat symptoms of various diseases. Various implantable medical devices such as deep brain stimulation (DBS) have been developed.

Among them, the deep brain stimulator is an implantable medical device that applies electrical stimulation to specific areas of the brain to alleviate the symptoms of brain diseases such as Parkinson's disease.

The deep brain stimulation device according to the prior art is composed of an electrode implanted in the brain, a control device implanted in the chest area to generate an electrical stimulation signal, and a connecting line connecting the electrode and the control device.

Among the above components, the control unit is composed of a microprocessor-based complex electronic circuit, a battery for five years of driving, an RF transceiver for communication with the outside, and the like, and is specifically designed for long-term stable operation in vivo. The basic structure of an artificial heart pacemaker (Cardiac Pacemaker), which is housed in a manufactured titanium case and sealed by laser welding, is used.

Therefore, the deep brain stimulation apparatus according to the prior art is expensive manufacturing cost of the control device, the size is too large, the transplant site is forced to descend to the chest, especially when the battery life is reached within five years must be replaced by a new control device through surgery There was a problem.

In order to solve this problem, Patent Document 1 and Patent Document 2 below disclose a deep brain stimulation device technology to which a wireless power transmission technology is applied.

Patent Literature 1 forms a rotating magnetic field by a rotating magnetic disk provided inside a hat worn by a patient, and generates induced power by an induction coil plate fixed to the lower part of the patient's scalp so as to be combined with the formed rotating magnetic field. A deep brain stimulation device configuration is described that is configured to drive an electrode implanted in a body, and that can correct abnormal motor and sensory functions using power wirelessly supplied from the outside of the human body.

Patent Literature 2 includes an internal device implanted in the scalp and an external device for supplying power to the internal device by a wireless power transmission method, wherein the wireless power transmitter of the external device is externally induced with a magnetic field by the power supplied from the battery. A coil and an external coil include an external magnet wound around, and the wireless power receiver of the internal device includes an internal coil aligned with the external coil so that AC power is formed by a magnetic field induced by the external coil, and an internal magnet wound inside the coil. By combining the external device to the internal device with the external coil and the internal coil aligned as the external magnet is attached to the internal magnet, by combining the wireless power transfer function, semi-permanent ultra-deep brain that does not require reoperation due to battery consumption The stimulation system configuration is described.

Republic of Korea Patent Registration No. 10-0877228 (August 26, 2008) Republic of Korea Patent Registration No. 10-1662594 (October 6, 2016 announcement)

The deep brain stimulation device to which the wireless power transmission technology according to the prior art including Patent Documents 1 and 2 described above is applied, induces induced power in a magnetically induced manner between the rotating magnetic field disk and the induction coil plate provided in the in vitro device and the device. Generate and send power to your device.

As a technology for transmitting power to the inside of the human body wirelessly, various methods have been tried to date, and electromagnetic induction and electromagnetic resonance methods and electromagnetic resonance methods and radio frequency (RF) methods using radio frequency, There is an ultrasonic method using ultrasonic waves.

The electric power transmission device using electromagnetic induction is composed of a charging matrix for generating charging power using an external power source, and a power receiving module receiving charging power through electromagnetic induction from the charging matrix. Is the closest technique to.

However, as electromagnetic waves are rapidly reduced in the air with distance inversely proportional to the distance squared, power transmission devices using electromagnetic induction are limited to the charging matrix and the power receiving module being used at close distances within a few cm of each other. .

For this reason, the deep brain stimulation device to which the wireless power transmission technology using the electromagnetic induction method according to the prior art is applied continuously as the power is transmitted from the in vitro device, regardless of the load fluctuations in the in-vivo device. Since power is consumed, there is a problem that power efficiency is lowered.

In addition, when applying a power receiver of the electromagnetic wave type embedded in the human body, as an antenna for a specific frequency band, malfunction occurs due to EMI (Electromagnetic Interface) interference when there is external electromagnetic noise using the frequency of the band. There was a problem.

In addition, in the electromagnetic wave method, when the transmitting unit generates electromagnetic waves, the receiving unit converts the electromagnetic waves into electric power by using a plurality of rectennas combining an antenna and a rectifier, and transmits the power to a long distance. There was a problem that is harmful to the human body.

In addition, the power transmission apparatus using the radio frequency collects energy of RF having a long propagation distance and supplies power to an electronic device or a sensor. RF exists in air a lot, and its propagation distance has a very wide advantage. However, RF has a problem of low energy density itself or low energy amount after energy conversion.

The ultrasonic wireless power transmission method uses the piezoelectric effect of the ferroelectric.

In other words, when mechanical force or compressive force is applied to both ends of the piezoelectric body, electricity is generated. On the contrary, when the electric field is applied, the displacement of contraction or relaxation occurs. The latter can generate ultrasonic waves, and the former generates ultrasonic waves. Electricity can be generated by pressure.

Therefore, the ultrasonic wireless power transmission method uses the piezoelectric phenomenon to generate the ultrasonic wave from the outside and transmit it to the human body, and then the ultrasonic receiver composed of the piezoelectric body transmits power by making acoustic energy (ultrasound) into electrical energy. .

Ultrasound is a sound wave, so unlike light, a medium is required to propagate and the transfer speed varies depending on the characteristics of the medium layer.

Since human tissue is 70% water, the rate of ultrasound delivery in the body has a value similar to that of water.

For this reason, ultrasound has been proved to be safe in the medical field and has been applied to patient care and medical devices.

The ultrasonic wave may use wireless power when the acoustic vibration generated from the ultrasonic device vibrates the transmission matching layer with the medium, and the piezoelectric mechanical energy is transmitted to the receiving device through the matching layer for oscillating the vibration.

The power transmission apparatus using the ultrasonic wave having such a feature is composed of a transmitting device for generating ultrasonic waves, and a receiving device for receiving the generated ultrasonic waves.

The ultrasonic wave power transmission device may be used in various media such as water or human skin. However, when the transmission device and the reception device are separated from each other by a medium such as water or human skin, the power transmission efficiency between the ultrasonic transmission and reception devices may be increased. There was a problem falling.

Accordingly, there is a demand for the development of a technology capable of supplying power to the internal apparatus wirelessly using ultrasonic waves and preventing a decrease in power transmission efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems as described above, and to provide an implantable medical device in the body capable of wirelessly transmitting power to a device implanted in the body using ultrasound in vitro.

Another object of the present invention is to provide an implantable medical device in the body which can improve the transmission efficiency of power transmitted to the device.

In order to achieve the above object, the implantable medical device according to the present invention is a power receiver for receiving the power transmitted by the wireless power transmission method using the ultrasonic wave in the power transmitter outside the body, the power received through the power receiver A battery for charging the battery, a case formed in a cylindrical shape having an open top surface, and a case forming an external shape, and a matching layer for packaging an upper surface of the case and matching an acoustic impedance of an ultrasonic signal transmitted through a medium layer from the power transmitter. The power receiver is provided as an ultrasonic transducer for converting an ultrasonic signal transmitted from the power transmitter into electrical energy, and the matching layer is combined with the power receiver to form a piezoelectric composite.

The ultrasonic transducer is provided as an array structure transducer for receiving a power by arranging a plurality of piezoelectric elements in the plurality of columns and rows, the horizontal and vertical length and height of the piezoelectric element, the spacing between each piezoelectric element is the arrangement structure It is characterized in that it is set based on the characteristics of the transducer.

The matching layer has a predetermined thickness on the space between each piezoelectric element and the upper portion of the piezoelectric element using a material of a biocompatible material having an acoustic impedance corresponding to the acoustic impedance of skin or blood of the human body forming the medium layer. It is characterized by being formed.

The present invention provides a stimulation unit for stimulating a nerve using the power supplied from the battery, a sensing unit for detecting a change in power load or biometric information in the process of stimulating the nerve, a communication unit for communicating with a management terminal in a wireless communication method and the And a control unit for controlling the operation of each device provided in the implantable medical device, wherein the control unit transmits the load information and the biometric information detected by the detection unit to the management terminal through the communication unit, and the stimulus The unit and the sensing unit may be provided at the same time, or only one of them.

The power transmitter may include a driving controller which converts electrical energy into an ultrasonic signal to generate an ultrasonic signal, and controls to transmit the generated ultrasonic signal, and a matching layer that matches an acoustic impedance with the power receiver.

As described above, according to the implantable medical device according to the present invention, the effect that the power can be transmitted to the implanted medical device by a wireless power transmission method using ultrasonic waves.

And according to the present invention, by forming a matching layer for matching the acoustic impedance in the space and the space between the plurality of piezoelectric elements constituting the array structure transducer, it is possible to minimize the return loss of the transmitted power to improve the wireless power transmission efficiency. Effect is obtained.

In addition, according to the present invention, using a material of a biocompatible material having a sound impedance similar to the skin or blood of the human body forming a medium layer for transmitting the ultrasonic signal, or biocompatible having a higher acoustic impedance than the skin or blood of the human body A matching layer is formed using a material of a material, and a structure for continuously changing the acoustic impedance on the matching layer is provided to prevent reflection of the ultrasonic signal, and the ultrasonic signal is transmitted to a power receiver provided below the matching layer. By transmitting so as to obtain the effect, the wireless power transmission efficiency using ultrasonic waves can be improved.

1 is a block diagram of a deep brain stimulation apparatus according to a preferred embodiment of the present invention,
2 is an exploded view of the deep brain stimulation apparatus shown in FIG.
3 is a table of human body tissue, brain tissue and water and acoustic impedance of each material;
4 is a view illustrating a structure of a power receiver and a matching layer;
5 is a cross-sectional view showing the structure of the piezoelectric element and the matching layer shown in FIG.
6 is a cross-sectional view illustrating a structure of a power receiver and a matching layer according to another embodiment of the present invention;
FIG. 7 is a partially enlarged view illustrating a structure of a power receiver and a matching layer shown in FIG. 6.

Hereinafter, an implantable medical device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the present embodiment, the deep brain stimulation apparatus in the implantable medical device in the body, but the present invention is not necessarily limited thereto.

That is, the present invention implants a device in the body to stimulate the nerves and supply the neurotransmitter artificial organs such as pacemakers or cochlear implants, gastric stimulator, spinal cord stimulator, heart used to alleviate or treat symptoms of various diseases It should be noted that it may be applied to a variety of implantable medical devices such as defibrillators, cardiac pacemakers, insulin pumps, foot drop implants.

1 is a block diagram of a deep brain stimulation apparatus according to a preferred embodiment of the present invention, Figure 2 is an exploded view of the deep brain stimulation apparatus shown in FIG.

Deep brain stimulation apparatus 10 according to a preferred embodiment of the present invention is implanted into the scalp, as shown in Figure 1, and the power supplied by the wireless power transmission method using ultrasonic waves from the power transmitter 12 in vitro To stimulate the cranial nerves.

In addition, the deep brain stimulation apparatus 10 detects a change in power load due to various factors such as skin thickness, hair growth rate, and blood flow change in the process of stimulating the cranial nerve, and transmits the detected load information to the management terminal 11. I can send it.

To this end, the deep brain stimulator 10 includes a power receiver 20 for receiving power transmitted from the power transmitter 12, a battery 30 for charging power received through the power receiver 20, and a battery 30. It includes a stimulator 40 for stimulating the cranial nerve using the power supplied from.

The deep brain stimulation apparatus 10 may further include a control unit 50 for controlling the driving of each device provided in the deep brain stimulation apparatus 10 and a communication unit 60 communicating with the management terminal 11 in a wireless communication manner. Can be.

The management terminal 11 receives the operation state information of the deep brain stimulation apparatus 10 and the information detected by the deep brain stimulation apparatus 10 through communication with the deep brain stimulation apparatus 10, the deep brain stimulation apparatus 10 Transmit a control command for operating the) and change or update the program of the deep brain stimulation apparatus 10.

The power transmitter 12 may be provided as an ultrasonic transducer that receives commercial power, converts electrical energy into an ultrasonic signal having a predetermined frequency, and transmits the converted ultrasonic signal to the deep brain stimulator 10. have.

The power transmitter 12 may include a driving control unit 13 that converts electrical energy into an ultrasonic signal to generate an ultrasonic signal and transmit the generated ultrasonic signal.

The power transmitter 12 may include a matching layer 14 for matching with the power receiver 20 of the deep brain stimulation apparatus 10 to be described below.

The power receiver 20 may be provided as an ultrasonic transducer that converts an ultrasonic signal transmitted from the power transmitter 12 into electrical energy and receives power.

To this end, the power receiver 20 may include a plurality of piezoelectric elements 21 for changing the voltage of the electric energy by the pressure of the ultrasonic signal (see FIG. 3).

The piezoelectric element 21 may be manufactured using lead zirconate titanate (PZT), which is a solid solution of zirconate (PbZrO3) and titanate (PbTiO3), a ceramic material having piezoelectric and superconducting properties.

Here, as shown in FIG. 2, the power receiver 20, the controller 50, the communicator 60, and the battery 30 are sequentially stacked in the case 80 along the vertical direction, and the power receiver 20 is provided. The upper side of the) is provided with a matching layer 70 for packaging the upper surface of the case 80, and matching with the power transmitter 12.

That is, the ultrasonic signal transmitted from the power transmitter 12 is transmitted to the power receiver 20 through a medium layer such as skin or blood of the human body.

The transmission efficiency of the power wirelessly transmitted between the power transmitter 12 and the power receiver 20 is characterized by the characteristics of the media layer, that is, the material, geometry, transmission medium and attenuation of the media layer. attenuation) and the distance between the power transmitter 12 and the power receiver 20.

Accordingly, the present invention minimizes the reflection loss of power transmitted to the power receiver 20 by using the materials and geometry of the matching layers 14 and 70 provided in the power transmitter 12 and the power receiver 20, respectively. The wireless power transmission efficiency can be improved.

The configuration of the power receiver 20 and the matching layers 14 and 70 will be described in detail with reference to FIGS. 3 to 5 below.

1 and 2, the battery 30 may be provided as a rechargeable secondary battery.

The stimulator 40 may include an internal microcontroller (not shown), a stimulation circuit (not shown), and a stimulation circuit for generating a specific stimulus waveform for stimulating the cranial nerve using DC power supplied from the battery 30. It may include a stimulation electrode for stimulating the cranial nerve in accordance with the generated stimulation waveform.

The controller 50 may be provided as a main control device for controlling the driving of each device provided in the deep brain stimulation device 10.

The controller 50 may control the driving of the stimulator 40 to adjust the stimulus applied to the core of the brain according to a driving program stored in a memory (not shown).

In addition, the control unit 50 transmits load information that detects a change in power load due to various factors, such as skin thickness, hair growth rate, and blood flow change, to the management terminal in the process of stimulating the cranial nerve through the communication unit 60. Can be controlled.

To this end, the deep brain stimulation apparatus 10 further includes a sensing means (not shown) capable of sensing the load information, and the sensing signal output from the sensing means may be transmitted to the controller 50. .

In addition to the load information, the sensing means may further include a plurality of sensing sensors for sensing various biometric information such as body temperature, blood pressure, respiratory rate, and temperature of the battery 30.

In addition, the controller 50 may control to change or update a program driving the stimulator 40 according to a control signal received from the management terminal 11 through the communication unit 60.

Meanwhile, in FIG. 2, the devices 80 and the devices 20, 30, 50, 60, and 70 accommodated inside the case 80 are illustrated in a cylindrical shape and a disc shape, but the present invention is not limited thereto. In some embodiments, the case 80 may be formed in a polygonal cylindrical shape such as a rectangular cylinder, and each device 20, 30, 50, 60, 70 accommodated in the case 80 may be modified in a polygonal plate shape.

Next, the configuration of the matching layer and the power receiver will be described in detail with reference to FIGS. 3 to 5.

In the present embodiment, a configuration of the matching layer 70 applied to the deep brain stimulation apparatus 10 implanted in the body will be described, but the present invention is not limited thereto, and the matching layer provided in the power transmitter 12 ( It should be noted that the same applies to 14).

As the matching layer 70 is implanted in the body, the matching layer 70 has an acoustic impedance similar to the skin and blood of the human body forming the medium layer, and uses a material of biocompatibility that satisfies human safety standards. Can be prepared.

The biocompatibility defines a bidirectional reaction, that is, the body's response to a substance and the response of the substances to the body environment.

In particular, the biocompatibility of a medical device represents the ability of the device to perform its intended function with the desired degree of binding in the host without eliciting unwanted local or systemic effects at the host.

In this embodiment, the biocompatible material is a medical grade or an implant grade material.

Therefore, in the present embodiment, the case 80 forming the outer shape of the deep brain stimulation apparatus 10 and the matching layer 70 packaging the upper surface of the case 80 are manufactured using a material of biocompatible material.

For example, the case 80 may be manufactured using a material made of a biocompatible metal such as titanium.

On the other hand, the acoustic impedance of skin is about 1.5 Mrayl, and the acoustic impedance of blood, ie, water, is about 1.48 Mrayl.

The acoustic impedance Z is the amount of sound pressure P acting on a plane parallel to the wavefront through which sound waves are transmitted divided by the volumetric velocity uS of the wave passing through the plane (Z = P / uS).

Therefore, the matching layer 70 is made of a silicon-based material, such as silicone rubber, which has a sound impedance similar to that of the human skin or blood constituting the medium layer, that is, about 1.48 to 1.6 Mrayl, and epoxy. Or a polymer compound such as a polymer such as polyurethane.

For example, FIG. 3 is a table of human tissue, brain tissue and water, and acoustic impedance for each material.

As shown in FIG. 3, the acoustic impedance of the silicon rubber is about 1.44 to 1.46 Mrayl, the acoustic impedance of the epoxy is about 1.52 Mrayl, and the acoustic impedance of the polyurethane is about 1.55 to 1.56 Mrayl.

Of course, according to the present invention, a matching layer having an acoustic impedance similar to the skin or blood of the human body may be manufactured by adding the above-described material and additives or functional materials when manufacturing the matching layer.

4 is a diagram illustrating a structure of a power receiver and a matching layer, and FIG. 5 is a cross-sectional view illustrating a structure of a piezoelectric element and a matching layer shown in FIG. 4.

The piezoelectric elements 21 of the power receiver 20 are arranged to form a plurality of columns and rows, as shown in FIGS. 4 and 5, and the matching layer 70 is a space between the piezoelectric elements 21 and the piezoelectric elements. The upper surface of the case 80 is formed to have a predetermined thickness on the upper portion 21.

The thickness of the matching layer 70 may be set to a thickness lower than the driving frequency wavelength of the ultrasonic signal, for example, 1/4 or less of the driving frequency wavelength.

As described above, the present invention fills a material having a sound impedance similar to the skin or blood of the human body constituting the medium layer between the piezoelectric elements provided in the power receiver to form a matching layer. By minimizing return loss, wireless power transmission efficiency can be improved.

On the other hand, the piezoelectric element 21 is formed in a rectangular parallelepiped shape having a substantially rectangular cross section, and the space between each piezoelectric element 21 is filled with a material for forming the matching layer 70 to be described below, so that the piezoelectric element 21 and the matching layer 70 are bonded to each other.

Accordingly, the power receiver 20 and the matching layer 70 may form an integrated piezoelectric composite.

As such, the power receiver 20 may be configured as a transducer having a structure in which a plurality of piezoelectric elements 21 are arranged to form a plurality of columns and rows (hereinafter, referred to as an “array structure transducer”).

In general, the quality of an ultrasound image in a medical device using ultrasound depends on axial resolution and lateral resolution.

The axial resolution increases as the length of the sound wave emitted from the transducer becomes shorter, and the length of the sound wave decreases as the wavelength becomes shorter as the frequency increases.

However, the higher the frequency, the greater the attenuation, the shorter the distance that sound waves can reach, which makes it difficult for ultrasound to propagate deep into the human body, reducing the imageable area and making the transducers thinner, making it difficult to manufacture transducers. Lose.

The side resolution increases as the width of the acoustic beam is narrower, and the acoustic beam is determined by the effective length and geometrical shape of the sound source relative to the wavelength.

When the array structure transducer increases the frequency in order to improve the axial resolution, the wavelength is shortened, so that the light receiving angle of each piezoelectric element 21 is narrowed, so as to prevent the acoustic beam formation from being performed properly. 21) to reduce the gap between them.

As a result, the manufacturing work of the transducer may be difficult, and the width of the image area may be narrowed.

Due to the characteristics of the ultrasound image, the image area and the resolution are determined according to the application target of the ultrasound-based medical device.

For example, medical devices that inspect internal organs or fetuses have a low resolution but should be able to see a wide image area. Medical devices that test ligaments and corneas are small and have a narrow image area adjacent to the skin. As a result, it should have a high resolution image.

Here, in order for the ultrasonic transducer to generate a short wavelength and a narrow acoustic beam, the thickness of each piezoelectric element 21 of the transducer should be thin and the interval between each piezoelectric element 21 should be narrowed.

However, the piezoelectric element 21 mainly used as an active element has a high brittleness, making it difficult to process and cut thinly.

In addition, although the array transducer having a large number of piezoelectric elements 21 installed in one structure can clinically obtain image information more easily, separation and electrical connection of each piezoelectric element 21 is difficult. .

Here, the separation of each piezoelectric element 21 generally uses a precision grinding process, and the spacing between each piezoelectric element 21 is narrow, so that the component is easily broken.

In addition, a flexible printed circuit board (FPCB) and a ground sheet (GRRS) are mainly used for uniform electrical connection to each of the plurality of piezoelectric elements 21. Since there are limitations in signal line spacing, It is difficult to use at minute intervals.

In addition, the propagation efficiency of the ultrasonic wave may be reduced by the acoustic impedance and the thickness of the ground sheet and the flexible printed circuit board.

Therefore, in the present embodiment, the power receiver 20 provided as the array structure transducer is not limited to the configuration shown in FIG. 4, and the amount of power wirelessly transmitted and the battery 30 based on the characteristics of the array structure transducer described above. The capacity of the power transmitter 12 and the power receiving unit 20 may be configured in various ways depending on various conditions such as intervals and specifications.

For example, the piezoelectric element 21 may be formed in a polygonal column shape such as a triangular shape or a square shape, or may be formed in a circular column shape having a circular cross section.

The width and length of the piezoelectric element 21 and the height and spacing between the piezoelectric elements 21 are variously changed to have an optimal transmission rate by using the actual wireless power transmission experiment results based on the characteristics of the array transducers described above. Can be set.

As described above, the present invention forms a matching layer for matching acoustic impedances in the space between and the plurality of piezoelectric elements constituting the array structure transducer, thereby minimizing the return loss of the transmitted power to improve wireless power transmission efficiency. You can.

Meanwhile, in the present exemplary embodiment, the matching layers 14 and 70 are formed by using a material made of a material having a sound impedance similar to the skin or blood of the human body constituting the medium layer, but the present invention is not necessarily limited thereto. .

6 is a cross-sectional view illustrating a structure of a power receiver and a matching layer according to another embodiment of the present invention, and FIG. 7 is an enlarged view illustrating a structure of the power receiver and a matching layer shown in FIG. 6.

Since the ultrasonic wave has the properties of the wavelength as the light, the present invention can minimize the energy loss by continuously changing the acoustic impedance of the medium that causes the ultrasonic wave to be reflected to prevent the reflection of the ultrasonic signal.

Therefore, the matching layer 70 applied to another embodiment of the present invention may be made of a material having a higher acoustic impedance than the acoustic impedance of skin or blood of the human body constituting the medium layer.

For example, the matching layer 70 uses a polymer compound such as polyethylene, polypropylene, or polyester having an acoustic impedance of about 1.5 to about 3 Mrayl higher than that of skin or blood. Can be prepared.

The acoustic impedance of the polyethylene is about 1.78 Mrayl, the acoustic impedance of polypropylene is about 2.24 Mrayl, and the acoustic impedance of polyester is about 2.86 Mrayl.

5 and 6, the matching layer 70 may have a plurality of conical or hemispherical protrusions 71 so as to continuously change the acoustic impedance of the medium layer.

Here, the distance (d) between the protrusions 71, the width (w) and the height (h) of each of the protrusions 71 calculates the wavelength according to the driving frequency by using Equation 1 below, and the calculated wavelength It can be set to smaller distances, widths, and heights.

As each protrusion 71 is formed in a conical shape or a semi-circular shape, the acoustic impedance of the matching layer 70 receiving the ultrasonic signal gradually increases downward.

That is, the matching layer 70 is filled with air having an acoustic impedance of about 0.000409Mrayl at the upper end of each protrusion 71, and the cross-sectional area of each protrusion 71 increases as it goes to the lower end of each protrusion 71. Accordingly, as the acoustic impedance gradually increases, the overall acoustic impedance of the matching layer 70 may be approximated to the impedance of the skin and blood of the human body.

Therefore, the structure of the protrusion 71 provided in the matching layer 70 may prevent reflection of the ultrasonic signal and transmit the ultrasonic signal to each piezoelectric element 21 of the power receiver 20.

As described above, the present invention forms a matching layer using a material of a material having a higher acoustic impedance than the acoustic impedance of the medium layer, and the length and width and height between the protrusions formed on the matching layer are smaller than the calculated wavelength. Can be set to distance, width and height.

Accordingly, the present invention prevents the reflection of the ultrasonic signal and transmits the ultrasonic signal to the power receiving unit provided under the matching layer, that is, the piezoelectric element array, thereby improving wireless power transmission efficiency using ultrasonic waves.

As mentioned above, although the invention made by the present inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

In the above embodiments, the configuration of the deep brain stimulation device in the implantable medical device has been described, but the present invention implants the device to stimulate the nerves to stimulate or reduce the symptoms of artificial pacemakers, such as artificial pacemakers It may be modified to be applicable to various implantable medical devices such as cochlear implant, gastric stimulator, spinal cord stimulator, cardiac defibrillator, cardiac pacemaker, insulin pump, and limb.

In the above embodiments, the stimulation unit and the sensing unit are described as being provided at the same time. However, the present invention provides only the stimulation unit to stimulate the nerves by providing only the stimulation unit and the sensor such as a BMI (Brain Machine Interface) to provide load information without stimulation. It may be changed to be applicable to medical devices that detect only biometric information.

The present invention is applied to the implantable medical device technology for transmitting power to the medical device implanted in the body by a wireless power transmission method using ultrasound.

10: Deep Brain Stimulator
11: management terminal 12: power transmitter
13: drive control unit 14: matching layer
20: power receiver 21: piezoelectric element
30: battery 40: magnetic pole
50: control unit 60: communication unit
70: matching layer 71: protrusion
80: case

Claims (5)

A power receiver configured to receive power transmitted from an external power transmitter by a wireless power transmission method using ultrasonic waves;
A battery for charging power received through the power receiver;
A case formed in a cylindrical shape with an upper surface opened and forming an outer shape;
A matching layer for packaging an upper surface of the case and matching an acoustic impedance of an ultrasonic signal transmitted through a medium layer in the power transmitter,
The power receiver is provided as an ultrasonic transducer for converting the ultrasonic signal transmitted from the power transmitter into electrical energy,
And the matching layer is combined with the power receiver to form a piezoelectric composite. The method of claim 1,
The ultrasonic transducer is provided as an array structure transducer for receiving a power by arranging a plurality of piezoelectric elements in the plurality of columns and rows,
The horizontal and vertical lengths and heights of the piezoelectric elements, and the spacing between the piezoelectric elements are set based on the characteristics of the array structure transducer. The method of claim 2,
The matching layer has a predetermined thickness on the space between each piezoelectric element and the upper portion of the piezoelectric element by using a material of a biocompatible material having an acoustic impedance corresponding to the acoustic impedance of skin or blood of the human body forming the medium layer. Intra-body implantable medical device, characterized in that it is formed. The method of claim 1,
Stimulator for stimulating the nerve using the power supplied from the battery,
Sensing unit for detecting fluctuations in power load or biometric information in the process of stimulating nerves,
Communication unit for communicating with the management terminal in a wireless communication method and
Further comprising a control unit for controlling the driving of each device provided in the implantable medical device,
The control unit controls to transmit the load information and the biometric information detected by the detection unit through the communication unit,
The implantable medical device, characterized in that the stimulation unit and the sensing unit is provided at the same time, or only one. The method of claim 1,
The power transmitter generates a ultrasonic signal by converting electrical energy into an ultrasonic signal, and a driving control unit for controlling to transmit the generated ultrasonic signal;
Intra-body implantable medical device comprising a matching layer for matching the acoustic impedance with the power receiver.

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