System and method for wireless power transmission to a ventricular assist device

Abstract

The present disclosure relates to a wireless power transmission system. The wireless power transmission system of the present disclosure includes an external transmitting resonator and an implantable receiving resonator. The external transmitting resonator is configured to wirelessly transmit power. The implantable receiving resonator is configured to receive the wirelessly transmitted power from the external transmitting resonator and use the received power to power a ventricular assist device (VAD) implanted in a subject. The external transmitting resonator includes (i) one or more loops of Litz wire and (ii) one of a plurality of laminated plates, and the implantable receiving resonator includes (i) one or more loops of Litz wire and (ii) the other of the plurality of laminated plates.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims priority based on U.S. Provisional Patent Application No. 62 / 987,468, filed on March 10, 2020. The entire disclosure of the above - mentioned application is incorporated herein by reference.

[0002] (Technical Field) The present disclosure generally relates to a wireless power transmission system, and more particularly to a wireless power transmission system used to supply power to a ventricular assist device.

Background Art

[0003] A ventricular assist device, known as a VAD, is an implantable blood pump and is generally used in patients suffering from a condition where the heart cannot provide sufficient circulation, called heart failure or congestive heart failure, both in the short - term (i.e., for several days or months) and long - term (i.e., for several years or a lifetime). Patients with heart failure can use a VAD while waiting for a heart transplant or as a long - term destination therapy. In another example, a patient can use a VAD during the recovery period after heart surgery. Thus, a VAD can assist a weakened heart (i.e., partially assist) or effectively replace the function of the natural heart.

[0004] A wireless power transmission system can be used to supply power to a VAD. Such a wireless power transmission system generally includes an external transmitting resonator and an implantable receiving resonator configured to be implanted in a patient's body. One of the problems of such a wireless power transmission system is to dissipate heat from the implantable receiving resonator in order to prevent the temperature in the patient's body from rising excessively. Furthermore, it is desirable for the wireless power transmission system to transmit power efficiently and be relatively easy to position within the patient's body.

Summary of the Invention

Means for Solving the Problem

[0005] The present disclosure relates to a wireless power transmission system. The wireless power transmission system of the present disclosure includes an external transmission resonator and an implantable reception resonator. The external transmission resonator is configured to wirelessly transmit power. The implantable reception resonator is configured to receive the power wirelessly transmitted from the external transmission resonator and supply power to a ventricular assist device (VAD) implanted in a subject using the received power. The external transmission resonator includes (i) a loop of one or more litz wires and (ii) one of a plurality of laminated plates, and the implantable reception resonator includes (i) a loop of one or more litz wires and (ii) the other of the plurality of laminated plates.

[0006] Also, the present disclosure relates to a wireless power transmission system. The wireless power transmission system of the present disclosure includes an external transmission resonator configured to wirelessly transmit power. Further, the wireless power transmission system of the present disclosure includes an implantable reception resonator configured to receive the power wirelessly transmitted from the external transmission resonator. The implantable reception resonator is configured to supply power to a ventricular assist device (VAD) implanted in a subject using the power received from the external transmission resonator.

[0007] Also, the present disclosure relates to a method for wirelessly transmitting power. The method of the present disclosure includes a step of wirelessly transmitting power from an external transmission resonator to an implantable reception resonator, wherein the external transmission resonator includes (i) a loop of one or more litz wires and (ii) one of a plurality of laminated plates. The method of the present disclosure further includes a step of the implantable reception resonator receiving the power wirelessly transmitted from the external transmission resonator, wherein the implantable reception resonator includes (i) a loop of one or more litz wires and (ii) the other of the plurality of laminated plates. The method of the present disclosure further includes a step of the implantable reception resonator supplying power to a ventricular assist device (VAD) implanted in a subject using the power received from the external transmission resonator.

[0008] Furthermore, the present disclosure relates to a method for wirelessly transmitting power. The method of the present disclosure includes the step of wirelessly transmitting power from an external transmitting resonator to an implanted receiving resonator. The method of the present disclosure further includes the steps of an implanted receiving resonator implanted in the chest cavity of a subject with a ventricular assist device (VAD) receiving the power wirelessly transmitted from the external transmitting resonator, and the implanted receiving resonator using the power received from the external transmitting resonator to supply power to the ventricular assist device (VAD).

Brief Description of the Drawings

[0009]

Figure 1

Figure 2A

Figure 2B

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Figure 4B

Figure 4C

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[0010] The present disclosure relates to a wireless power transmission system. The implantable receiving resonator of the wireless power transmission system of the present disclosure is configured to be implanted within a patient's thoracic cavity to improve heat dissipation. In some embodiments, the wireless power transmission system of the present disclosure can be a hybrid system that uses a first resonator including a loop of litz wire and a second resonator including a laminate.

[0011] Referring now to the drawings, FIG. 1 shows a simplified electrical circuit of an exemplary wireless power transmission system 100. The wireless power transmission system 100 includes an external transmitting resonator 102 and an implantable receiving resonator 104. The wireless power transmission system 100 is of a series connection type in which capacitors Cx and Cy are electrically connected in series to inductors Lx and Ly, but the wireless power transmission system 100 may be connected in series or in parallel to the transmitting resonator 102 or the receiving resonator 104.

[0012] In this exemplary wireless power transmission system 100, a power source Vs is electrically connected to the transmitting resonator 102 to supply power to the transmitting resonator 102. The receiving resonator 104 is connected to a load 106. The receiving resonator 104 and the load 106 may be electrically connected to a switching or rectifying device (not shown).

[0013] In an exemplary embodiment, the transmitting resonator 102 includes a coil Lx connected to a power supply Vs by a capacitor Cx. The receiving resonator 104 includes a coil Ly connected to a load 106 by a capacitor Cy. The coil Lx (inductor Lx) and the coil Ly (inductor Ly) are connected with a coupling coefficient k. Mxy is the mutual inductance between the two coils. The mutual inductance Mxy has a relationship as shown in the following formula (1) with the coupling coefficient k.

[0014]

Number

[0015] During operation, the transmitting resonator 102 wirelessly transmits the power supplied from the power supply Vs. The receiving resonator 104 receives the power wirelessly transmitted from the transmitting resonator 102 and supplies the received power to the load 106.

[0016] FIGS. 2A and 2B show an exemplary configuration for supplying power to a mechanical circulatory assist system 202 implanted in a patient's body 204 using a wireless power transmission system 100. The mechanical circulatory assist system 202 includes an implantable blood pump assembly 206. This blood pump assembly 206 includes a blood pump 208, a ventricular cuff 210, and an outflow cannula 212. The receiving resonator 104 supplies power to the blood pump assembly 206.

[0017] The blood pump assembly 206 can be implemented in a ventricular assist device (VAD) attached to the top of the left ventricle, the right ventricle, or both ventricles of the heart 214 as shown in the figure. One end of the blood pump assembly 206 is attached to the heart 214 via a ventricular cuff 210 coupled to the blood pump assembly 206 sutured to the heart 214. The other end of the blood pump assembly 206 is connected to the ascending aorta or the descending aorta via the outflow cannula 212. The blood pump assembly 206 efficiently diverts blood from the weakened ventricle, supplies it to the aorta via the outflow cannula 212, and circulates it to the rest of the patient's vascular system.

[0018] One of the problems in a power transmission system for a ventricular assist device (VAD) is to dissipate the heat generated by an implantable module. For example, an implantable coil module disposed in the chest region has a heat balance of about 0.4 W, and if it exceeds this, a temperature rise of more than 2°C can occur. However, the electrical engineering design of the implantable coil module tends to release more than 0.4 W of heat with only the coil windings. In addition, heat is also generated by rectification from alternating current (AC) to direct current (DC), and various electronic devices, microcontrollers, and digital signal processors of a transcutaneous energy transmission system (TETS). The abdominal implantation position is easy to manage heat because the perfusion in the surrounding tissue is relatively high, but still, considering the amount of heat released from the implanted module, it is still unacceptable. Furthermore, since a relatively complicated surgery (for example, a surgery penetrating the diaphragm) is required to implant a receiving resonator in the patient's abdomen, from a surgical perspective, placement in the abdomen is not desirable.

[0019] Therefore, in the illustrated embodiment, to facilitate heat management, the receiving resonator 104 is disposed within the patient's thoracic cavity 217. In some embodiments, the receiving resonator 104 is disposed below the patient's lung 220 and above the diaphragm 222. Alternatively, the receiving resonator 104 may be implanted above the diaphragm 222. As a result, the receiving resonator 104 generally comes into thermal contact with the lung 220, and the heat is dissipated via the pulmonary circulation.

[0020] The receiving resonator 104 includes one or more loops of litz wire 216, or a plurality of laminated plates 218. For example, in some embodiments, the transmitting resonator 102 includes one or more loops of litz wire 216, and the receiving resonator 104 includes a plurality of laminated plates 218. Alternatively, the receiving resonator 104 includes one or more loops of litz wire 216, and the transmitting resonator 102 includes a plurality of laminated plates 218. In yet another example, both the transmitting resonator 102 and the receiving resonator 104 may include one or more loops of litz wire 216, or both the transmitting resonator 102 and the receiving resonator 104 may include a plurality of laminated plates 218.

[0021] In some embodiments, the receiving resonator 104 is coupled to the blood pump assembly 206 (as shown in FIGS. 2B and 5). For example, the loops of one or more litz wires 216 included in the receiving resonator 104 are wound around the ventricular cuff 210 (as shown in FIG. 2B). In another configuration (shown in FIG. 5), the plurality of laminated plates 218 included in the receiving resonator 104 are coupled to the blood pump 208. In this case, the ventricular cuff 210 is configured to extend through an opening defined by the laminated plates 218. In these configurations, the receiving resonator 104 is in thermal contact with the blood pump assembly 206, and heat is dissipated through the aortic flow passing through the blood pump assembly 206.

[0022] In this exemplary embodiment, the wireless power transmission system 100 is configured as a hybrid system in which the transmitting resonator 102 is (i) a loop of one or more litz wires 216 and (ii) one of the plurality of laminated plates 218, and the receiving resonator 104 is (i) a loop of one or more litz wires 216 and (ii) the other of the plurality of laminated plates 218. For example, in the embodiment shown in FIG. 2A, the wireless power transmission system 100 includes a transmitting resonator 102 including a loop of one or more litz wires 216 and a receiving resonator 104 including a plurality of laminated plates 218. In contrast, in the embodiment shown in FIG. 2B, the wireless power transmission system 100 includes a transmitting resonator 102 including a plurality of laminated plates 218 and a receiving resonator 104 including a loop of one or more litz wires 216. Generally, the geometric shape of the loop of the litz wire 216 can be changed relatively easily. Thus, the loop of the litz wire 216 can be wound around the patient's body 204 (as shown in FIG. 2A) or around the blood pump assembly 206 (as shown in FIG. 2B). In comparison, the resonator including the laminated plates 218 has a higher power transfer efficiency than the resonator including the litz wire 216. Thus, a hybrid wireless power transmission system using one resonator of each type can realize the advantages of both types of resonators.

[0023] During operation, the transmission resonator 102 and the reception resonator 104 are arranged close to each other. For example, when the reception resonator 104 is arranged inside the thoracic cavity 217 of a patient, the transmission resonator 102 is arranged on the side of the chest region of the patient or wound around the periphery of the chest region of the patient.

[0024] FIG. 3A is a schematic diagram showing the configuration of the resonators 102 and 104, which are laminate resonators 300 including a plurality of laminate plates 218. FIG. 3B is an exploded view of the laminate resonator 300 shown in FIG. 3A. A similar laminate resonator is described in "Thin Self-Resonant Structures with a High-Q for Wireless Power Transfer" by Stein et al., March 4, 2018, Thayer School of Engineering, Dartmouth College, Hanover, NH. For clarity, the thickness of the laminate plate 218 is exaggerated. In reality, the thickness of each laminate plate 218 can be in the range of 10 to 200 μm (for example, more specifically, 20 to 70 μm). The laminate resonator 300 includes a plurality of laminate plates 218. Those skilled in the art will understand that the laminate resonator 300 may include any suitable number of laminate plates 218. The laminate plates 218 are laminated on the magnetic core 306.

[0025] The magnetic core 306 includes a bottom portion 310, a peripheral wall portion 312, and a post portion 314. As shown in FIGS. 3A and 3B, each laminate plate 218 has an opening 320 sized to receive the post portion 314 and is arranged between the post portion 314 and the peripheral wall portion 312 of the magnetic core 306 so as to generally surround the post portion 314.

[0026] The laminate 218 is formed by alternately laminating a plurality of dielectric layers 322 and conductive layers 324. In the embodiments shown in FIGS. 3A and 3B, each dielectric layer 322 is an annular plate having a substantially O-shaped configuration and extending between an inner diameter and an outer diameter. Each conductive layer 324 has a substantially C-shaped configuration so as to define a notch 326 and extends between an inner diameter and an outer diameter. Each conductive layer 324 extends circumferentially over an angle less than 360° (referred to herein as the "angle span") to define the notch 326.

[0027] Further, each conductive layer 324 is oriented in a direction opposite to that of the adjacent conductive layer 324 sandwiching the dielectric layer 322 such that the notches 326 of the conductive layers 324 adjacent to each other across the dielectric layer 322 form an angle of 180° with each other. Due to such an opposite orientation, two capacitors are formed by the conductive layers 324 adjacent to each other across the dielectric layer 322.

[0028] In one embodiment, one conductive layer 324 is a bottom conductive layer 330 having two terminals 332. By these two terminals 332, the laminate resonator 300 is connected to, for example, a power supply (when functioning as a transmitting resonator) or a load 106 (when functioning as a receiving resonator). Further, in some embodiments, the laminates 218 forming the top and bottom of the laminate are conductive layers 324 instead of dielectric layers 322. Alternatively, the dielectric layer 322 may be disposed at the top and / or bottom of the laminate.

[0029] During operation, when power is supplied to the laminate resonator 300 operating as a transmitting resonator, the current flows through the capacitor formed by the conductive layer 324, thereby forming an induced current loop. Specifically, the laminate resonator 300 functions as a parallel LC resonator and can wirelessly transmit power to the receiving resonator 104 or receive power wirelessly transmitted from the transmitting resonator 102.

[0030] The resonance frequency of the laminate resonator 300 can be, for example, about 6.78 MHz. Specifically, the resonance frequency of the laminate resonator 300 is inversely proportional to the square root of the product of the inductance and capacitance of the laminate resonator 300. The inductance and capacitance are determined based on the design of the laminate resonator 300. Therefore, the resonance frequency can be changed by changing the design of the laminate resonator 300.

[0031] For the wireless power transmission system 100 to function, the resonance frequencies of the transmitter and receiver resonators 102, 104 need to overlap each other. The resonance frequency of a resonator including a loop of Litz wire is generally up to 2.8 MHz, and the resonance frequency of a resonator including a laminate can be about 6.78 MHz. Also, the resonance frequencies of the resonators 102, 104 are inversely proportional to the square root of the product of the inductance and capacitance of the resonators 102, 104, and the inductance is proportional to the coil diameter. In the case of the resonators 102, 104 including a laminate, the capacitance is proportional to the area of the laminate. If the radial width of the laminate is the same, the capacitance is also proportional to the coil diameter. In an embodiment where the laminate 218 surrounds the blood pump assembly 206, the coil diameter of the laminate 218 is increased so that the resonance frequency of the laminate 218 falls within the upper limit range of the resonance frequency of the loop of the Litz wire 216. In order to make the overlap of the resonance frequencies easier, the capacitance between the laminates 218 can be changed by adjusting the dielectric constant of the material of the dielectric layer 322 or by adjusting the thickness of the dielectric layer 322.

[0032] Wireless power transmission system 100 can further include an implantable battery module 402 electrically connected to the blood pump assembly 206. FIGS. 4A-4D are schematic diagrams of exemplary configurations of the receiving resonator 104, the battery module 402, and the blood pump assembly 206. In these embodiments, the first electrical cable 404 and the second electrical cable 406 can be used to provide the electrical connection. In FIGS. 4A-4D, a receiving resonator 104 including loops of one or more litz wires 216 is used as an example. Those skilled in the art will understand that a receiving resonator 104 including a plurality of laminated plates 218 can be used instead of the receiving resonator 104 including loops of one or more litz wires 216 and connected to the battery module 402 and the blood pump assembly 206.

[0033] In FIGS. 4A and 4B, the receiving resonator 104 is directly electrically connected to the blood pump assembly 206 using the first electrical cable 404. Thereby, both the receiving resonator 104 and the battery module 402 can directly supply power to the blood pump assembly 206 and function as backups for each other. For example, the receiving resonator 104 is electrically connected to the blood pump assembly 206 via the first electrical cable 404, the first end 408 of the first electrical cable 404 is connected to the receiving resonator 104, and the second end 410 of the first electrical cable 404 is connected to the blood pump assembly 206. Also, the battery module 402 is electrically connected to the blood pump assembly 206 via the second electrical cable 406, the first end 412 of the second electrical cable 406 is connected to the battery module 402, and the second end 414 of the second electrical cable 406 is connected to the blood pump assembly 206.

[0034] In FIGS. 4C and 4D, the battery module 402 is electrically connected between the receiving resonator 104 and the blood pump assembly 206. For example, the battery module 402 is electrically connected to the receiving resonator 104 via a first electrical cable 404, a first end 408 of the first electrical cable 404 is connected to the receiving resonator 104, and a second end 410 of the first electrical cable 404 is connected to the battery module 402. Further, the battery module 402 is electrically connected to the blood pump assembly 206 via a second electrical cable 406, a first end 412 of the second electrical cable 406 is connected to the battery module 402, and a second end 414 of the second electrical cable 406 is connected to the blood pump assembly 206.

[0035] Figure 5 shows another configuration of a wireless power transmission system 100 that supplies power to a ventricular assist device (VAD). In this embodiment, the transmitting resonator 102 includes a loop of one or more litz wires 216 (shown in FIG. 2A), and the receiving resonator 104 of the wireless power transmission system 100 includes a plurality of laminated plates 218 (shown in FIG. 2A). The receiving resonator 104 is disposed in proximity to the blood pump assembly 206. Also, the receiving resonator 104 is disposed below the lung 220 and above the diaphragm 222. The wireless power transmission system 100 further includes a hub 502 formed integrally with the transmitting resonator 102. The hub 502 and the transmitting resonator 102 may be included within a wearable accessory 504. The wearable accessory 504 can be, for example, a messenger bag. Thus, the transmitting resonator 102 is configured to wrap around the patient's body 204 from the patient's shoulder 506 to the opposite hip 508 of the patient. For example, when the receiving resonator 104 is disposed at or near the left ventricular apex of the heart 214, optimally, the wearable accessory 504 is worn from the left shoulder to the right hip. In some embodiments, the wearable accessory 504 may include structural non-magnetic components, such as plastic pins or plastic meshes, that increase the rigidity of the wearable accessory 504 against torsion. In such a configuration, it is desirable to prevent the wearable accessory 504 from twisting in an 8 shape so that the magnetic field of the transmitting resonator 102 is not partially canceled out. Such reinforcing elements still allow the wearable accessory 504 to bend slightly. That is, when the wearable accessory 504 is regarded as an ellipse, the lengths of the major axis and the minor axis of the ellipse can be varied for comfort.

[0036] In an exemplary embodiment, the hub 502 may include a power converter (not shown) configured to convert the power supplied from the power source into power to be supplied to the transmission resonator 102. The power converter may be configured to convert the direct current power (DC power) supplied from the power source into alternating current power (AC power) at the operating frequency of the wireless power transmission system 100. The direct current power (DC power) may be supplied from an external battery. Optionally, the hub may include a power converter that converts the alternating current power (AC power) supplied from a wall outlet into direct current power (DC power) having the same DC voltage as that supplied by the battery. Alternatively, the power converter may be arranged in a component separate from the hub 502, such as a separate power module or the like.

[0037] Figure 6 is a flowchart of an exemplary method 600 for wirelessly transmitting power. The method 600 includes a step 606 of wirelessly transmitting power from an external transmission resonator to an implantable reception resonator, where the external transmission resonator includes (i) a loop of one or more litz wires and (ii) one of a plurality of laminated plates. The method 600 further includes a step 608 of the implantable reception resonator receiving the power wirelessly transmitted from the external transmission resonator, where the implantable reception resonator includes (i) a loop of one or more litz wires and (ii) the other of the plurality of laminated plates. The method 600 further includes a step 610 of the implantable reception resonator using the power received from the external transmission resonator to supply power to a ventricular assist device (VAD).

[0038] Figure 7 is a flowchart of another exemplary method 700 for wirelessly transmitting power. The method 700 includes a step of wirelessly transmitting power from an external transmission resonator to an implantable reception resonator. The method 700 further includes a step 708 of the implantable reception resonator, implanted in the thoracic cavity of a subject with a ventricular assist device (VAD) implanted therein, receiving the power wirelessly transmitted from the external transmission resonator. The method 700 further includes a step 710 of the implantable reception resonator using the power received from the external transmission resonator to supply power to a ventricular assist device (VAD).

[0039] The embodiments and examples disclosed in this specification have been described with reference to specific embodiments, but it should be understood that these embodiments and examples are merely illustrative of the principles and applications of the present disclosure. Therefore, it should be understood that various changes can be made to the exemplary embodiments and examples without departing from the spirit and scope of the present disclosure as defined by the claims, and other configurations can be devised. Therefore, this application is intended to cover modifications and variations of these embodiments and their equivalents.

[0040] This specification discloses the content of the present invention, including the best mode, using examples, and enables those skilled in the art to practice the present invention (including the manufacture and use of any device or system and the practice of any incorporated method). The patented technical scope of the present invention is defined by the claims in the claims, and other embodiments conceivable by those skilled in the art may also be included. Such other embodiments shall be included within the scope of the claims if they include components that do not differ from the language of each claim, or if they include equivalent components that do not substantially differ from the language of each claim.

Claims

1. A wireless power transmission system, comprising: an external transmission resonator configured to wirelessly transmit power; an implantable reception resonator configured to receive the power wirelessly transmitted from the external transmission resonator and supply power to a ventricular assist device (VAD) implanted in a subject using the received power; the external transmission resonator includes one or more loops of Litz wire; the implantable reception resonator includes a plurality of laminated plates; the implantable reception resonator is disposed adjacent to the pump such that a ventricular cuff of the pump of the ventricular assist device (VAD) extends through an opening defined by the plurality of laminated plates; the implantable reception resonator is in thermal contact with the pump of the ventricular assist device (VAD) and is provided to promote heat dissipation through the pump, the wireless power transmission system.

2. The wireless power transmission system according to claim 1, wherein the one or more loops of Litz wire are configured to be wound around the upper body of the subject.

3. The wireless power transmission system according to claim 2, wherein the external transmission resonator is configured to be obliquely wound around the upper body of the subject from the shoulder to the hip of the subject.

4. The wireless power transmission system according to claim 1, further comprising a hub integrally formed with the external transmission resonator, the hub includes a power converter configured to convert first power provided from a power source into second power received by the external transmission resonator.

5. The wireless power transmission system according to claim 1, wherein the implantable reception resonator is configured to be implanted into the chest cavity of the subject.

6. The wireless power transmission system according to claim 1, wherein the dimensions of the plurality of laminated plates are set such that the resonance frequency of the implantable reception resonator overlaps with the resonance frequency of the external transmission resonator.

7. The wireless power transmission system according to claim 1, wherein the implantable reception resonator is configured to be implanted below the lung of the subject and above the diaphragm of the subject.

8. The wireless power transmission system according to claim 1, wherein A wireless power transmission system further including an implantable battery module electrically connected to the ventricular assist device (VAD).

9. The wireless power transmission system according to claim 8, wherein the implantable battery module is electrically connected between the implantable receiving resonator and the ventricular assist device (VAD), and the implantable receiving resonator is configured to supply power to the ventricular assist device (VAD) by charging the implantable battery module.

10. The wireless power transmission system according to claim 8, wherein the implantable receiving resonator is directly electrically connected to the ventricular assist device (VAD).

11. A method for operating the external transmitting resonator of the wireless power system according to claim 1, the method including the step of the external transmitting resonator wirelessly transmitting power to the implantable receiving resonator of the wireless power system.

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