An electrode assembly for applying a tumor treatment field (TT field), comprising a plurality of graphite sheets that are thermally coupled but electrically insulated

Abstract

An alternating electric field (e.g., a TT field) may be applied to a subject's body using an electrode assembly that includes a plurality of graphite sheets (or sheets of another anisotropic conductive material) that are each arranged adjacent to one another but do not touch each other. One or more electrode elements are arranged to be in electrical contact with each of the graphite sheets. Strips of electrically insulating and thermally conductive material are arranged between the graphite sheets, and these strips are positioned to be in thermal contact with the graphite sheets. The graphite sheets promote passive heat dissipation within the extent of any given sheet. Further, the strips of material can continue passive heat dissipation beyond the extent of any given sheet without compromising the electrical insulation between the sheets.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of U.S. Provisional Application No. 63 / 357,111, filed Jun. 30, 2022, which is hereby incorporated by reference in its entirety.

Background Art

[0002] Tumor treating fields (TT fields) therapy is a proven approach for treating tumors using an alternating electric field at a frequency of, for example, 50 kHz to 1 MHz, more commonly 100 to 500 kHz. The alternating electric field is induced by an electrode assembly (e.g., an array of capacitive coupling electrodes, also referred to as a transducer array) placed on opposite sides of the subject's body. When an alternating voltage is applied between the opposing electrode assemblies, an alternating current flows through the electrode assembly into the subject's body. And a higher current is strongly correlated with a higher therapeutic effect.

[0003] FIG. 1A is a schematic view of a prior - art electrode assembly 40 including nine prior - art electrode elements labeled X1 - X9. FIG. 1B is a schematic cross - sectional view of the electrode elements X1 - X3 of the electrode assembly 40 along the dashed line of FIG. 1A.

[0004] As shown in FIG. 1B, the electrode element X1 (by way of example) includes a metal layer (shown with diagonal hatching) and a ceramic (dielectric) layer. Layers of conductive hydrogel are provided between each ceramic layer and the subject's skin to ensure good electrical contact between the electrode element and the body. An alternating voltage from an alternating voltage generator (not shown) is applied to the metal layer of the electrode elements within the opposing electrode assemblies to generate a TT field within the subject's body.

[0005] During use, since the skin under the hydrogel and the electrode elements is heated, considering safety, the skin temperature needs to be maintained below a safe threshold (for example, 41 °C). Since most of the heat appears directly under the electrode elements X1 to X9, in the electrode assemblies of the prior art, there are hot spots directly under the electrode elements, and low-temperature regions are located between the electrode elements. And those hot spots limit the amount of current that can be delivered through the electrode assemblies of the prior art.

Summary of the Invention

Means for Solving the Problems

[0006] One aspect of the present application relates to a first electrode assembly including a first sheet of anisotropic conductive material having a front side and a front surface and a rear side and a rear surface, and one or more first electrode elements arranged to be in electrical contact with the first sheet respectively. The first electrode assembly also includes a second sheet of anisotropic conductive material having a front side and a front surface and a rear side and a rear surface, and one or more second electrode elements arranged to be in electrical contact with the second sheet respectively. The second sheet is arranged adjacent to the first sheet without contacting the first sheet. The first electrode assembly also includes a first strip of electrically insulating and thermally conductive material disposed between the first sheet and the second sheet. The first strip of material is positioned to be in thermal contact with both the first sheet and the second sheet.

[0007] In some embodiments of the first electrode assembly, the first strip of material includes coated graphite. In some embodiments of the first electrode assembly, the width of the first strip of material is less than 2 mm. In some embodiments of the first electrode assembly, the first sheet and the second sheet include a synthetic graphite sheet, pyrolytic graphite, a graphitized polymer film, or a graphite foil made from compressed high-purity exfoliated mineral graphite.

[0008] Some embodiments of the first electrode assembly further include a first layer of skin - compatible conductive material disposed on the front side of the first sheet and a second layer of skin - compatible conductive material disposed on the front side of the second sheet.

[0009] In some embodiments of the first electrode assembly, there are at least two first electrode elements and at least two second electrode elements. Each first electrode element includes a first metal layer and a first dielectric layer disposed on the first metal layer. Each first dielectric layer is disposed to be in electrical contact with the first sheet and is located behind the first sheet. Each second electrode element includes a second metal layer and a second dielectric layer disposed on the second metal layer. Each second dielectric layer is disposed to be in electrical contact with the second sheet and is located behind the second sheet.

[0010] Optionally, in the embodiments of the previous paragraph, each of the first dielectric layers and each of the second dielectric layers include a polymer layer having a dielectric constant of at least 10. Optionally, in the embodiments of the previous paragraph, the electrical contact between each of the first dielectric layers and the first sheet is made using a first layer of conductive gel or conductive adhesive, and the electrical contact between each of the second dielectric layers and the second sheet is made using a second layer of conductive gel or conductive adhesive.

[0011] In some embodiments of the first electrode assembly, there are at least two first electrode elements and at least two second electrode elements. Each first electrode element includes a first metal layer disposed to be in electrical contact with the first sheet, and each second electrode element includes a second metal layer disposed to be in electrical contact with the second sheet.

[0012] In some embodiments of the first electrode assembly, there are at least two first electrode elements and at least two second electrode elements, and the electrode assembly further includes a plurality of first metal conductors each disposed to be in electrical contact with only one of the first electrode elements respectively, and a plurality of second metal conductors each disposed to be in electrical contact with only one of the second electrode elements respectively.

[0013] In some embodiments of the first electrode assembly, there are at least two first electrode elements and at least two second electrode elements, and the electrode assembly further includes at least one first metal conductor arranged to be electrically connected to all of the first electrode elements and at least one second metal conductor arranged to be electrically connected to all of the second electrode elements.

[0014] Some embodiments of the first electrode assembly further include a support having an adhesive backing having a shape and dimensions such that the front side of the first sheet and the front side of the second sheet face the human body side and the electrode assembly can be applied to the human body.

[0015] Some embodiments of the first electrode assembly are coils, and the energy from the conductor power supply is bypassed by the coil, locally accumulated in the conductor, and reused to power a controller, a circuit, or means for generating digital data related to temperature measurement.

[0016] In some embodiments of the first electrode assembly, there are at least two first electrode elements and at least two second electrode elements, and the electrode assembly further includes a third sheet of anisotropic conductive material having a front side and a front face and a rear side and a rear face, a plurality of third electrode elements each arranged to be in electrical contact with the third sheet, and a second strip of electrically insulating and thermally conductive material arranged between the second sheet and the third sheet. The third sheet is arranged adjacent to the second sheet without contacting the second sheet and without contacting the first sheet, and the second strip is positioned to be in thermal contact with both the second sheet and the third sheet.

[0017] Optionally, the embodiments of the preceding paragraph further include a plurality of first metal conductors each arranged to be in electrical contact with only one of the first electrode elements, a plurality of second metal conductors each arranged to be in electrical contact with only one of the second electrode elements, and a plurality of third metal conductors each arranged to be in electrical contact with only one of the third electrode elements.

[0018] In some embodiments of the first electrode assembly, there are at least two first electrode elements and at least two second electrode elements, and the electrode assembly further includes a third sheet of anisotropic conductive material having a front side and a front face and a rear side and a rear face, a plurality of third electrode elements each arranged to be in electrical contact with the third sheet, a second strip of electrically insulating and thermally conductive material disposed between the second sheet and the third sheet, a first layer of skin - compatible conductive material disposed on the front side of the first sheet, a second layer of skin - compatible conductive material disposed on the front side of the second sheet, and a third layer of skin - compatible conductive material disposed on the front side of the third sheet. The third sheet is disposed adjacent to the second sheet without contacting the second sheet and without contacting the first sheet, and the second strip is positioned to be in thermal contact with both the second sheet and the third sheet. In these embodiments, the first and second strips of material each include coated graphite.

[0019] Another aspect of the present application relates to a second electrode assembly including a first sheet of anisotropic conductive material having a front side and a front face and a rear side and a rear face, at least one first electrode element arranged to be in electrical contact with the first sheet, a second sheet of anisotropic conductive material disposed adjacent to the first sheet without contacting the first sheet, at least one second electrode element arranged to be in electrical contact with the second sheet, and a strip of electrically insulating and thermally conductive material disposed between the first sheet and the second sheet. The strip of material is positioned to be in thermal contact with both the first sheet and the second sheet.

[0020] In some embodiments of the second electrode assembly, the strip of material comprises graphite coated thereon. In some embodiments of the second electrode assembly, the width of the first strip of material is less than 2 mm. In some embodiments of the second electrode assembly, the first sheet and the second sheet comprise a synthetic graphite sheet, pyrolytic graphite, a graphitized polymer film, or a graphite foil made from compressed high-purity exfoliated mineral graphite.

[0021] Another aspect of the present application relates to a first method of planning the treatment of a target region of a subject's body using an alternating electric field. The first method includes positioning a first set of N electrode elements on a first side of a target region on or within the subject's body. Each of the N electrode elements is arranged to be in electrical contact with a sheet of anisotropic conductive material, and N is at least 4. The first method also includes positioning a second set of M electrode elements on a second side of the target region on or within the subject's body. Each of the M electrode elements is arranged to be in electrical contact with a sheet of anisotropic conductive material, and M is at least 4. The second side is opposite the first side. The first method also includes sequentially measuring the impedance or conductance between each of the N electrode elements of the first set and each of the M electrode elements of the second set during a first time period, calculating a first impedance or conductance at each of at least 27 voxels corresponding to positions between the first set of N electrode elements and the second set of M electrode elements based on the measurement of the impedance or conductance, and formulating a plan for treating the target region using an alternating electric field based on the first impedance or conductance of the voxels.

[0022] In some examples of the first method, a plurality of strips of electrically insulating and thermally conductive material are disposed between adjacent sheets of anisotropic conductive material and positioned to be in thermal contact with said adjacent sheets. In some examples of the first method, the sheets of anisotropic conductive material each comprise a synthetic graphite sheet, pyrolytic graphite, a graphitized polymer film, or a graphite foil made from compressed high-purity exfoliated mineral graphite. In some examples of the first method, the plan includes creating a recommendation to move at least one set of electrode elements to different positions on or within the body of the subject.

[0023] Some examples of the first method further include, following the creation of the plan, applying an alternating voltage between a plurality of electrode elements in the first set and a plurality of electrode elements in the second set to induce an electric field in the target region.

Brief Description of the Drawings

[0024]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3

Figure 4A

Figure 4B

Figure 5

Figure 6

Figure 7A

Figure 7B

Figure 8

Best Mode for Carrying Out the Invention

[0025] Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings, where the same reference numerals represent the same elements. This application describes an exemplary electrode assembly that can be used, for example, to deliver an alternating electric field to a subject's body. The alternating electric field may be a tumor treatment field (TT field) for treating one or more cancers or tumors located within the subject's body, and most of the following examples assume that situation. However, the electrode assemblies described herein may be used to deliver other electrical signals, including alternating electric fields applied for purposes other than treating tumors. For example, the electrode assemblies described herein may be used to apply an alternating electric field to increase the permeability of the blood-brain barrier (e.g., as described in U.S. Patent No. 10,967,167) or to increase the permeability of cell membranes (e.g., as described in U.S. Patent No. 11,103,698).

[0026] When a TT field is applied to a subject's body, the subject's body temperature may increase in proportion to the increase in the intensity of the induced electric field. By regulation, the amount of current that can be driven through the electrode assembly is limited to an amount that keeps the temperature measured at each part of the subject's body below a temperature threshold. As practiced in the art, the temperature at the location of the electrode assembly on the subject's body is controlled to be below the temperature threshold by reducing the operating current driven by the electrode assembly, thereby reducing the resulting intensity of the TT field. This is a major limitation on the intensity of the TT field that can be used for tumor treatment.

[0027] In an electrode assembly including a plurality of electrode elements, the portion of the electrode assembly located directly below the electrode elements is at a higher temperature than the portion of the electrode assembly located between the electrode elements. Further, in an electrode assembly including a plurality of electrode elements, more current flows through the electrode elements located along the edge of the array compared to the electrode elements located near the center of the array. Further, the electrode elements located at the corners of the edge of the array or similar sharp bends will have a higher current than other electrode elements near the edge and center of the array. The tendency of the electrode assembly to pass a higher current along the edge of the array, particularly through the electrode elements located at the corners, is referred to as the "edge effect".

[0028] The non-uniform distribution of current flowing through the electrode assembly due to the distribution of the electrode elements or the edge effect can cause high temperature zones (or "hot spots") at the corners or edges of the electrode assembly. Since these hot spots are the locations where the threshold temperature is first reached, the requirement to reduce the current is controlled. Therefore, the generation of hot spots limits the maximum operating current that can be driven by the electrode assembly and the resulting intensity of the TT field.

[0029] In this application, various approaches are described that reduce or minimize the non-uniform current distribution within the electrode assembly, thereby ultimately enabling the use of a higher operating current without exceeding the threshold temperature. An electrode assembly operated with an increased current can induce a stronger TT field within the subject's body, ultimately leading to an improvement in the patient's outcome. With the electrode assembly disclosed herein, the current and heat are distributed more uniformly throughout the array, thereby minimizing or eliminating hot spots.

[0030] The approach described below in connection with FIGS. 2A, 2B and 4-8 uses a sheet of anisotropic conductive material (e.g., a sheet of pyrolytic graphite) incorporated into the electrode assembly to passively carry heat away from hot spots in order to reduce or minimize hot spots on the electrode assembly as described below. Thereby, when a predetermined alternating voltage is applied to the electrode assembly, the temperature of the hot spots decreases (compared to the prior art configurations of FIGS. 1A and 1B described above), and the temperature of the low temperature regions increases. Thus, the current can be increased (thereby increasing the therapeutic effect) without exceeding the safety temperature threshold at any point on the subject's skin.

[0031] FIG. 2A is a schematic view of an electrode assembly 50 of one embodiment including electrode elements for applying a TT field to a subject's body, and FIG. 2B is a cross-sectional view of the same electrode assembly 50 taken along the dashed line of FIG. 2A. In FIG. 2A, only four electrode elements labeled E1 - E4 are shown, although additional electrode elements may be included in the electrode assembly 50. In an alternative embodiment, the electrode assembly 50 includes only a single electrode element.

[0032] The electrode assembly 50 includes an anisotropic conductive material (e.g., a sheet of graphite) 70 having a front side and a front face (facing the subject's skin in FIG. 2B) and a rear side and a rear face. Examples of suitable forms of graphite include synthetic graphite such as pyrolytic graphite (including, but not limited to, pyrolytic graphite sheets (PGS) available from Panasonic Industry, Kadoma City, Osaka Prefecture), graphite foils made from compressed high-purity exfoliated mineral graphite (including, but not limited to, MinGraph® 2010A Flexible Graphite available from Mineral Seal, Tucson, Arizona, USA), graphitized polymer films such as graphitized polyimide films (including, but not limited to, those made by Kaneka Corporation, Mobara City, Tochigi Prefecture), etc., but are not limited thereto. Note that in the examples described herein and shown in the figures, the anisotropic conductive material sheet is described and shown as a graphite sheet. In alternative embodiments, an anisotropic conductive material other than graphite may be used instead of graphite.

[0033] The exemplary embodiments described herein incorporate a sheet of material having anisotropic thermal and / or electrical properties (also referred to herein as an anisotropic material sheet) into the electrode assembly. When the sheet of material has anisotropic thermal properties (e.g., when the in-plane thermal conductivity is greater than the out-of-plane thermal conductivity), the sheet spreads heat more uniformly over a larger surface area. When the sheet of material has anisotropic electrical properties (e.g., when the in-plane conductivity is greater than the out-of-plane conductivity, or conversely, when the in-plane resistance is lower than the out-of-plane resistance), the sheet spreads current more uniformly over a larger surface area. In either case, when a predetermined alternating voltage is applied to the device, the temperature of the hot spots decreases and the temperature of the cold regions increases. Thus, the current can be increased without exceeding the safety temperature threshold at any point on the subject's skin (thereby increasing the therapeutic effect).

[0034] In some embodiments, the anisotropic material is anisotropic with respect to conductivity characteristics. In some embodiments, the anisotropic material is anisotropic with respect to thermal conductivity characteristics. In some embodiments, the anisotropic material is anisotropic with respect to both conductivity characteristics and thermal conductivity characteristics.

[0035] Anisotropic thermal properties include directional thermal properties. Specifically, the anisotropic material sheet has a first thermal conductivity in a direction perpendicular to its front surface. And the thermal conductivity of the sheet in a direction parallel to the front surface exceeds twice the first thermal conductivity. In some preferred embodiments, the thermal conductivity in the parallel direction exceeds ten times the first thermal conductivity. For example, the thermal conductivity of the sheet in a direction parallel to the front surface can exceed 1.5 times, 2 times, 3 times, 5 times, 10 times, 20 times, 100 times, 200 times, or even 1,000 times the first thermal conductivity.

[0036] Anisotropic electrical properties include directional electrical properties. Specifically, the anisotropic material sheet has a first resistance in a direction perpendicular to its front surface. And the resistance of the anisotropic material sheet in a direction parallel to the front surface is lower than the first resistance. In some preferred embodiments, the resistance in the parallel direction is less than half of the first resistance, or less than 10% of the first resistance. For example, the resistance of sheet 70 in a direction parallel to the front surface may be less than 75%, 50%, 40%, 30%, 20%, 10%, 5%, 1%, 0.5%, or 0.1% of the first resistance.

[0037] In some embodiments (for example, when the anisotropic material sheet is a pyrolytic graphite sheet), the anisotropic material sheet has both anisotropic electrical properties and anisotropic thermal properties. Preferably, the anisotropic material is non-metallic.

[0038] The electrode assembly 50 further includes a surface layer 60 of a biocompatible conductive material disposed on the front side (e.g., the front surface) of the graphite sheet 70. The material surface layer 60 is configured to ensure good electrical contact between the device and the body. In some embodiments, the material surface layer 60 covers the entire front surface of the graphite sheet 70. The size of the material surface layer 60 may be the same as or larger than that of the graphite sheet 70. In some embodiments, the conductive material surface layer 60 includes a hydrogel. In these embodiments, the thickness of the hydrogel may be 50 to 2,000 μm, such as 100 to 1,000 μm, or 300 to 500 μm. In some embodiments, the conductive material surface layer 60 is a non-hydrogel biocompatible conductive adhesive. In some embodiments, the conductive material surface layer 60 is a non-hydrogel biocompatible conductive adhesive, and this non-hydrogel biocompatible conductive adhesive is, for example, the developed product FLX068983 - FLEXcon® OMNI-WAVE 商標TT 200 BLACK H-502 150 POLY H-9 44PP-8 (FLEXcon, Spencer, MA, USA), or other similar OMNI-WAVE products of FLEXcon, or the ARcare® 8006 conductive adhesive composition manufactured and sold by Adhesives Research, Inc. (Glen Rock, PA, USA). The non-hydrogel conductive adhesive may include an adhesive anhydrous polymer having conductive fillers (e.g., carbon particles, powders, fibers, flakes or nanotubes) disposed therein. The adhesive polymer may be, for example, an acrylic polymer or a silicone polymer, or a combination thereof, and can be obtained as an acrylic or silicone carbon-filled adhesive tape. The adhesive may further include one or more conductive polymers (e.g., polyaniline (PANI), poly(3,4-ethylenedioxythiophene) (PEDOT), or other polymers known in the art). When present, the conductive fillers on the surface layer 60 of the conductive material should be non-metallic. In these embodiments, the thickness of the biocompatible conductive adhesive may be 10 to 2,000 μm, such as 20 to 1,000 μm, or 30 to 400 μm.

[0039] The electrode assembly 50 further includes electrode elements E1 to E4 located behind the graphite sheet 70. Each electrode element E1 to E4 has a front surface arranged to be in electrical contact with the rear surface of the graphite sheet 70. Each electrode element E1 to E4 includes a dielectric layer 310 having a front surface and a rear surface, and a metal layer 320 provided on the rear surface of the dielectric layer 310. The front surface of the dielectric layer 310 is the front surface of the electrode elements E1 to E4. The dielectric 310 in these embodiments may be, for example, a flat ceramic material having a high dielectric constant (as shown in FIGS. 2A and 2B), or a polymer layer having a dielectric constant of at least 10.

[0040] In some embodiments, the dielectric constant of the dielectric layer 310 may be in the range of 10 to 50,000. In some embodiments, the dielectric layer 310 includes a high dielectric polymer material such as poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) and / or poly(vinylidene fluoride-trifluoroethylene-1-chlorofluoroethylene). These two polymers are abbreviated as "poly(VDF-TrFE-CTFE)" and "poly(VDF-TrFE-CFE)" respectively in this specification. These embodiments are particularly advantageous because the dielectric constants of these materials are about 40. In some embodiments, the polymer layer may be poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene-chlorofluoroethylene) or "poly(VDF-TrFE-CTFE-CFE)".

[0041] In some embodiments, the dielectric layer 310 includes a terpolymer including polymerization units of monomers in any suitable molar ratio such as VDF, TrFE, CFE, and / or CTFE. Suitable terpolymers include, for example, those having 30 to 80 mol% of VDF and 5 to 60 mol% of TrFE, with CFE and / or CTFE constituting the remainder of the mol% of the terpolymer.

[0042] The electrode assembly 50 further includes a conductive material layer 380 disposed between the front surfaces of the electrode elements E1 to E4 (i.e., the front surface of the dielectric layer 310) and the rear surface of the graphite sheet 70. The conductive material layer 380 facilitates electrical contact between the front surfaces of the electrode elements E1 to E4 and the rear surface of the graphite sheet 70. In some embodiments, the conductive material layer 380 is a hydrogel layer. However, in alternative embodiments, it is also possible to use different conductive materials (e.g., conductive grease, conductive adhesive, conductive tape, conductive composite materials, etc.). In some embodiments, the conductive material layer 380 may be a non-hydrogel conductive adhesive as described above. In an alternative embodiment (not shown), instead of disposing individual conductive material layers 380 between the front surfaces of each of the electrode elements E1 to E4 and the rear surface of the graphite sheet 70, a single large conductive material layer may be disposed between the front surfaces of all of the electrode elements E1 to E4 and the rear surface of the graphite sheet 70.

[0043] The metal layers 320 of all of the electrode elements (i.e., E1 to E4 in the illustrated embodiment) may be wired together with the leads 90 (e.g., using wires, traces on a flexible substrate, etc.). The leads 90 supply an alternating voltage to the electrode elements from an alternating voltage generator (not shown) to generate a TT field when the electrode assembly 50 is attached to the subject's body for treatment.

[0044] Optionally, the device may include a coil that redirects energy from a primary conductor power source through the coil and locally stores it in a capacitor for reuse in powering a controller (e.g., a controller that controls a duty cycle), or a circuit or device (e.g., for switching) may reuse the power in powering means that generate digital data related to temperature measurement.

[0045] Optionally, the electrode assembly 50 includes a flexible self-adhesive backing 55 configured to support the graphite sheet 70, the electrode elements E1 to E4, and the conductive material surface layer 60, thereby allowing the front surface of the conductive material surface layer 60 to be disposed against the subject's skin.

[0046] As described above, FIG. 2A is a schematic plan view of an electrode assembly including electrode elements E1 to E4. When an AC voltage is applied to the electrode elements E1 to E4, current and heat are dissipated by the graphite sheet 70, and hot spots are minimized or eliminated. Since both current and heat in this embodiment are dissipated over a wider area, hot spots are eliminated (or at least minimized). This means that for a given applied AC voltage, the hottest point under the electrode assembly in the embodiments of FIGS. 2A and 2B is lower in temperature than the hottest point under the electrode assembly in the prior art embodiment of FIG. 1. Therefore, the current can be increased (compared to the prior art current) without exceeding the safety temperature threshold at any point under the electrode assembly. And this increase in current advantageously enhances the effectiveness of TT field therapy.

[0047] The embodiments described in connection with FIGS. 2A and 2B make a very important contribution to lowering the temperature of the hottest spot of any given electrode assembly by passively conducting heat from the hottest spot of the electrode assembly to cooler spots of the electrode assembly using a single graphite sheet. And this passive heat conduction results in the effect that the electrode assembly can carry a higher current without exceeding the safety temperature threshold at any point of the electrode assembly.

[0048] However, in certain anatomical situations, the passive heat distribution technique described in connection with FIGS. 2A and 2B may not be able to dissipate heat sufficiently from the hottest spot of the electrode assembly. When this occurs, (since increasing the current further will cause the hottest spot to exceed the safety temperature threshold,) the hottest spot of the electrode assembly will continue to limit the amount of current that can be supplied through any given electrode assembly.

[0049] As an example of such an anatomical situation, the TT field may be applied between a 9-element electrode assembly positioned at the front and top of the subject's head (referred to herein as the front array) and a second 9-element electrode assembly positioned at the back of the subject's head (referred to herein as the rear array). In this anatomical situation, when the same signal is applied to all 9 electrode elements in FIGS. 1A and 1B, as shown in FIG. 3 (a schematic diagram of the heat map of the front array in this situation), the last 3 elements of the front array and the top 3 elements of the rear array typically become much hotter than the remaining elements of these arrays. More specifically, in the example of FIG. 3, the last 3 elements of the front array operate at about 37.5 °C, while the other 6 elements operate at about 36.25 °C. Furthermore, in this anatomical situation, in the passive heat distribution technique described in relation to FIGS. 2A and 2B, there may be cases where heat cannot be sufficiently dissipated from the hottest spots on the electrode assembly.

[0050] As one possible approach to making the temperature of the electrode elements of an electrode assembly uniform, there is a redesign of the electrode assembly such that the individual electrode elements can be independently activated using separate wires (e.g., 9 wires per electrode assembly containing 9 electrode elements). In this specification, this approach is referred to as the "independent element approach".

[0051] Another possible approach to making the temperature of the electrode elements uniform is to wire the electrode elements in groups such that each group can be activated independently of the other groups. For example, in the case of the electrode elements of a 9-element electrode assembly as shown in FIG. 3, the 3 elements on the left side of the page may be connected to one wire, the 3 elements in the center may be connected to a second wire, and the 3 elements on the right side of the page may be connected to a third wire. In this specification, this approach is referred to as the "group-by-element approach".

[0052] In both the independent element approach and the grouped element approach, the temperature of the hottest electrode element in FIG. 3 can be reduced by reducing the duty cycle of the signal driving the hottest electrode element. More specifically, when the heat map shown in FIG. 3 shows the temperature obtained when all electrode elements are driven using the same signal, in the independent element approach, the temperature of the three electrode elements on the left side of the page can be reduced by reducing the duty cycles of the three signals driving these three electrode elements. Similarly, when implementing the grouped element approach, the temperature of the three electrode elements on the left side of the page can be reduced by reducing the duty cycle of the single signal driving these three electrode elements.

[0053] In the independent element approach, the method of reducing the duty cycle of the signal applied to a given electrode element to lower its temperature is effective only when maintaining electrical insulation between different electrode elements. The reason is that when there is a conductive path between one electrode element and another, it seems impossible to apply a signal to one electrode element without applying the same signal to another electrode element.

[0054] Similarly, in the grouped element approach, the method of reducing the duty cycle of the signal applied to a given group of electrode elements to lower the temperature of the electrode elements within the group is effective only when maintaining electrical insulation between different groups of electrode elements. The reason is that when there is a conductive path between one group of electrode elements (for example, the three electrode elements on the left side) and another group of electrode elements (for example, the three electrode elements on the right side), it seems impossible to apply a signal to the first group of electrode elements without applying the same signal to the second group of electrode elements.

[0055] As a cause, electrical insulation between electrode elements (or between groups of electrode elements) is an essential condition for reducing the temperature of any given electrode element (or group of electrode elements) using a technique based on a duty cycle, and the technique based on the duty cycle described in this section cannot be combined with the embodiments of FIGS. 2A and 2B that rely on a single anisotropic conductive material (e.g., graphite sheet 70) to dissipate heat from the hottest electrode elements. This is because the electrode elements E1 to E4 in FIGS. 2A and 2B are each electrically connected to the same graphite sheet 70 via their respective conductive materials 380. Since the conductivity of graphite is very high, the graphite sheet 70 in the embodiments of FIGS. 2A and 2B breaks the electrical insulation between various electrode elements (or groups of electrode elements). Furthermore, to function correctly, the techniques based on the duty cycle require maintaining electrical insulation, and these techniques are incompatible with the embodiments of FIGS. 2A and 2B.

[0056] Figures 4A and 4B are a plan view and a cross-sectional view of a mechanical layout of one embodiment of an electrode assembly that advantageously enables coexistence of a technique based on a duty cycle for lowering the temperature of a specific electrode element and a passive heat diffusion technique based on an anisotropic conductive material sheet (e.g., a graphite sheet). This embodiment includes a plurality of anisotropic conductive material sheets (e.g., graphite sheets 20), and each sheet has a front surface and a rear surface. (As used herein, the front surface faces the subject's body, and the rear surface faces away from the subject's body.) Note that FIG. 4A shows three graphite sheets 20, and the number of graphite sheets may be changed, for example, between 2 and 20. Examples of suitable forms of graphite for manufacturing the graphite sheet 20 include several synthetic graphites such as pyrolytic graphite, graphitized polymer film, and graphite foil made from compressed high-purity exfoliated mineral graphite. Also, although FIG. 4A shows the graphite sheets 20 oriented in the vertical direction, the graphite sheets 20 may be oriented in the horizontal direction. Note that in the examples described herein and shown in the figures, the anisotropic conductive material sheet is described and shown as a graphite sheet. In alternative embodiments, an anisotropic conductive material other than graphite may be used instead of graphite.

[0057] The plurality of electrode elements are arranged to be in electrical contact with each of the graphite sheets 20. In the illustrated embodiment, each of the first electrode elements (E1 to E3) is arranged to be in electrical contact with the first graphite sheet 20 (i.e., the left sheet in FIG. 4A), each of the second electrode elements (E4 to E6) is arranged to be in electrical contact with the second graphite sheet 20 (i.e., the central sheet in FIG. 4A), and each of the third electrode elements (E7 to E9) is arranged to be in electrical contact with the third graphite sheet 20 (i.e., the right sheet in FIG. 4A). Note that FIG. 4A shows three electrode elements arranged to contact each of the graphite sheets 20, but the number of electrode elements associated with each graphite sheet may be changed, for example, between 1 and 10. Needless to say, when the number of electrode elements associated with each graphite sheet is 1, only a single electrode element (instead of a plurality of electrode elements) is arranged to be in electrical contact with each graphite sheet 20.

[0058] The second graphite sheet 20 is positioned adjacent to the first graphite sheet 20 without touching the first graphite sheet 20. When three or more graphite sheets 20 are included, the graphite sheets need to be positioned adjacent to each other without touching. For example, in the embodiment of FIG. 4A, the third graphite sheet is positioned adjacent to the second graphite sheet 20 without touching the second graphite sheet 20 and without touching the first graphite sheet 20.

[0059] The first strip 25 of the electrically insulating and thermally conductive material is disposed between the first graphite sheet 20 and the second graphite sheet 20, and the first strip of this material is positioned so as to be in thermal contact with both the first graphite sheet 20 and the second graphite sheet 20. When three or more graphite sheets 20 are included, it is necessary to dispose additional strips of the electrically insulating and thermally conductive material between the graphite sheets. For example, in the embodiments of FIGS. 4A and 4B, the second strip 25 of the electrically insulating and thermally conductive material is disposed between the second graphite sheet 20 and the third graphite sheet 20, and the second strip 25 of this material is positioned so as to be in thermal contact with both the second graphite sheet and the third graphite sheet.

[0060] The purpose of these strips 25 of the electrically insulating and thermally conductive material is to dissipate the heat to the adjacent graphite sheets even if any of the graphite sheets 20 is at the highest temperature, thereby lowering the temperature of the hottest point of the entire electrode assembly. Note that, unlike the situation of FIGS. 2A and 2B (where none of the electrode elements are electrically insulated from each other), the strips 25 of the material are electrically insulated, and thus electrically insulate the adjacent graphite sheets 20. As a result, in the embodiment of FIGS. 4A and 4B, the electrode elements E1 to E9 are not all electrically connected to the same graphite sheet 70. Therefore, electricity cannot flow from one graphite sheet 20 to another graphite sheet 20. That is, different signals can be applied to separate groups of electrode elements.

[0061] In some preferred embodiments, each strip 25 of the material includes coated graphite. The coating may be a tape, but is not necessarily limited thereto, and may be, for example, a tape such as an acrylic tape, a polyester (polyethylene terephthalate, PET) tape, a high-temperature resistant polyether ether ketone (PEEK) tape, or a polyimide tape. However, in alternative embodiments, the strip 25 of the material can be made of other materials including, but not limited to, hexagonal boron nitride, a coated (as described above) insulating metal sheet, a thermally conductive metal oxide, or diamond. In some preferred embodiments, the width of each strip 25 of the material is less than 2 mm. However, in alternative embodiments, the width of the strip 25 of the material may be larger (for example, 2 - 5 mm wide).

[0062] Furthermore, the embodiments of FIGS. 4A and 4B also include a layer 15 of a skin-compatible conductive material disposed on the front side of each graphite sheet. In some embodiments, including the embodiments of FIGS. 4A and 4B, the layer 15 of the skin-compatible conductive material is disposed on the front surface of each graphite sheet. Examples of suitable skin-compatible conductive materials include hydrogels, conductive greases, and acrylic adhesives based on conductive carbon fillers such as the OMNI-WAVE adhesive composition manufactured and sold by FLEXCON (Spencer, Massachusetts, USA), or the ARcare® 8006 conductive adhesive composition manufactured and sold by Adhesives Research, Inc. (Glen Rock, Pennsylvania, USA). In use, the front surface of the conductive material layer 15 maintains contact with the user's skin. The skin-compatible conductive material 15 may touch or partially overlap the strip 25 of the electrically insulating material, but care should be taken that the skin-compatible conductive material 15 does not reach the strip 25 of the electrically insulating material to such an extent as to impair the electrical insulation function of the strip 25 of the electrically insulating material.

[0063] In some embodiments, including the embodiments of FIGS. 4A and 4B, electrode elements E1 - E9 are capacitive coupling electrode elements. In these embodiments, each electrode element has a metal layer for receiving an alternating current signal and a dielectric layer disposed on each metal layer. Each of the dielectric layers E1 - E9 of the electrode elements is disposed to be in electrical contact with and located behind each respective graphite sheet 20. For example, in the embodiments shown in FIGS. 4A and 4B, each of electrode elements E1 - E3 is disposed to be in electrical contact with and has a dielectric layer located behind the first graphite sheet 20 (i.e., the left sheet), each of electrode elements E4 - E6 is disposed to be in electrical contact with and has a dielectric layer located behind the second graphite sheet 20 (i.e., the middle sheet), and each of electrode elements E7 - E9 is disposed to be in electrical contact with and has a dielectric layer located behind the third graphite sheet 20 (i.e., the right sheet).

[0064] In these embodiments, the dielectric layer may be, for example, a flat ceramic material having a high dielectric constant, a polymer layer having a dielectric constant of at least 10, or any of the dielectrics described above in connection with FIGS. 2A and 2B. In these embodiments, the electrical contact between each dielectric layer of electrode elements E1 - E9 and each respective graphite sheet 20 is made using a conductive adhesive layer. However, in alternative embodiments, the electrical contact between each dielectric layer of electrode elements E1 - E9 and each respective graphite sheet 20 can be made using another approach (e.g., a conductive gel layer such as a hydrogel) using any of the approaches described above in connection with FIGS. 2A and 2B.

[0065] The embodiments of FIGS. 4A and 4B also include a support 30 having an adhesive backing. This support can be made of, for example, cloth or a foamed material (e.g., similar to a conventional self - adhesive bandage). The support 30 has a shape and dimensions such that the electrode assembly can be applied to the human body with the graphite sheet facing the human body side.

[0066] The electrical connection to the electrode elements E1 to E9 in the embodiments of FIGS. 4A and 4B may be implemented using various approaches, including the independent element approach and the grouped element approach described above.

[0067] FIG. 5 shows a preferred set of electrical connections to the electrode elements E1 to E9 for implementing the independent element approach when each of the electrode elements E1 to E9 includes a metal layer and a dielectric layer (as shown in FIGS. 4A and 4B). The thick dots in the lower right quadrant of each of the electrode elements E1 to E9 indicate the electrical contact between the dielectric layer of each of the electrode elements E1 to E9 and the respective graphite sheet 20. Any of the graphite forms described above in connection with FIGS. 4A and 4B may be used in the embodiment of FIG. 5, or a non-graphite anisotropic conductive material may be used. Individual metal conductors (e.g., one or more wires and / or conductive traces) extend from the respective metal layers of the electrode elements E1 to E9 to the respective pins of the connector 35. Further, these metal conductors transmit the AC signal applied to the connector 35 to the respective metal layers of the electrode elements E1 to E9. Thus, each individual electrode element can be independently activated using an independent wire. However, it should be noted that this independence is impaired within the scope of any one of the graphite sheets 20 because each graphite sheet 20 conducts electricity.

[0068] When the wiring structure shown in FIG. 5 is used, by reducing the duty cycle of the signals applied to the three electrode elements on the left (i.e., electrode elements E1 to E3 in FIGS. 4 and 5), the problem shown in FIG. 3 (the three elements on the left become hotter than the remaining electrode elements) can be improved. In particular, since each of the graphite sheets 20 has thermal conductivity, each graphite sheet also serves a passive function of dissipating heat from the hottest electrode element within any given sheet. Further, since the strip 25 of material has thermal conductivity, passive heat dissipation is not limited to the constraints of any given single graphite sheet. On the contrary, for the hottest graphite sheet 20, a part of its heat can be diffused to the surrounding graphite sheets through the strip 25 of the material having thermal conductivity. Therefore, the embodiments of FIGS. 2A and 2B advantageously combine a duty cycle-based technique for reducing temperature, which is compatible with the passive heat dissipation technique for reducing temperature.

[0069] As described above, since each graphite sheet 20 conducts electricity, the independence of all electrode elements within any given graphite sheet 20 is impaired. In view of this, as shown in FIG. 6, by collectively wiring all the electrode elements arranged in parallel on any given graphite sheet 20, results very similar to those described above in connection with FIG. 5 can be obtained.

[0070] FIG. 6 shows an alternative preferred set of electrical connections to electrode elements E1 - E9 for implementing a group - by - element approach when each of the electrode elements E1 - E9 includes a metal layer and a dielectric layer (as shown in FIGS. 4A and 4B). The thick dots in the lower - right quadrant of each of the electrode elements E1 - E9 indicate the electrical contact between the dielectric layer of each of the electrode elements E1 - E9 and its respective graphite sheet 20. Any of the graphite forms described above in connection with FIGS. 4A and 4B may be used in the embodiment of FIG. 6, or a non - graphite anisotropic conductive material may be used. A set of metal conductors (e.g., wires or conductive traces) extends from all of the metal layers of three electrode elements E1 - E3 to one pin of the connector 35. Another set of metal conductors extends from all of the metal layers of three electrode elements E4 - E6 to another pin of the connector 35. Yet another set of metal conductors extends from all of the metal layers of three electrode elements E7 - E9 to yet another pin of the connector 35. Each set of metal conductors transmits an AC signal applied to the connector 35 to the metal layers of each group of electrode elements (i.e., E1 - E3, E4 - E6, or E7 - E9) respectively. Thus, each group of electrode elements can be activated independently of the other groups using separate wires.

[0071] Accordingly, the wiring structure shown in FIG. 6 is another approach to improving the problem shown in FIG. 3 (the left - hand three elements becoming hotter than the remaining electrode elements) by reducing the duty cycle of the signal applied to the three electrode elements. Again, in this case, since each of the graphite sheets 20 has thermal conductivity, each graphite sheet also performs a passive function of dissipating heat from the hottest electrode element within any given sheet. Also, if it is the hottest graphite sheet 20, a portion of its heat can be spread to the surrounding graphite sheets via a strip 25 of a thermally conductive material. Thus, the embodiments of FIGS. 4 and 6 advantageously combine both a duty - cycle - based technique for reducing temperature and a passive heat - dissipation technique for reducing temperature.

[0072] As yet another approach to the electrical connection to the electrode elements E1 to E9, all of the electrode elements E1 to E9 are wired in parallel while being dispersed on different graphite sheets (for example, the graphite sheets as described above in connection with FIG. 6). By utilizing this approach, only a single electrical connection to the connector is required to energize all nine elements.

[0073] The embodiments described above in connection with FIGS. 4 to 6 are premised on the fact that each of the electrode elements E1 to E9 is a capacitive coupling type electrode element including a metal layer positioned behind the dielectric layer. However, the scope of the present application is not limited to capacitive coupling type electrode elements. On the contrary, electrode elements that are not of the capacitive coupling type may be employed.

[0074] FIGS. 7A and 7B are a plan view and a cross-sectional view of a mechanical layout of another embodiment of an electrode assembly that advantageously enables coexistence of a technique based on a duty cycle for lowering the temperature of a specific electrode element and a passive heat diffusion technique based on an anisotropic conductive material sheet (for example, a graphite sheet). This embodiment also includes a plurality of anisotropic conductive material sheets (for example, graphite sheets 20), and each sheet has a front surface and a rear surface. Although FIG. 7A shows three graphite sheets 20, the number of graphite sheets may be changed, for example, between 2 and 20. The form of graphite described above in connection with FIGS. 4A and 4B may be used in the embodiment of FIGS. 7A and 7B, or a non-graphite anisotropic conductive material may be used instead of graphite.

[0075] The plurality of electrode elements E1 to E9 are arranged so as to be in electrical contact with each of the graphite sheets 20. For example, in the illustrated embodiment, each of the first electrode elements (E1 to E3) is arranged so as to be in electrical contact with the first graphite sheet 20 (i.e., the left sheet in FIG. 7A), each of the second electrode elements (E4 to E6) is arranged so as to be in electrical contact with the second graphite sheet 20 (i.e., the central sheet in FIG. 7A), and each of the third electrode elements (E7 to E9) is arranged so as to be in electrical contact with the third graphite sheet 20 (i.e., the right sheet in FIG. 7A). Note that FIG. 7A shows three electrode elements arranged so as to be in contact with each of the graphite sheets 20, but the number of electrode elements associated with each graphite sheet may be changed, for example, between 1 and 10. Needless to say, when the number of electrode elements associated with each graphite sheet is 1, only a single electrode element (not a plurality of electrode elements) is arranged so as to be in electrical contact with each graphite sheet 20.

[0076] The second graphite sheet 20 is positioned adjacent to the first graphite sheet 20 without touching the first graphite sheet 20. When three or more graphite sheets 20 are included, as described above in connection with the embodiments of FIGS. 4A and 4B, the graphite sheets need to be positioned adjacent to each other without touching each other.

[0077] As described above in connection with the embodiments of FIGS. 4A and 4B, strips 25 of one or more electrically insulating and thermally conductive materials are disposed between the graphite sheets 20. The purpose of these strips 25 of electrically insulating and thermally conductive materials is to spread the heat to adjacent graphite sheets, no matter which graphite sheet 20 is at the highest temperature, thereby reducing the temperature of the hottest point of the entire electrode assembly. Note that, unlike the situation in FIGS. 2A and 2B (where none of the electrode elements are electrically insulated from each other), the strips 25 of material are electrically insulated and thus electrically insulate the adjacent graphite sheets 20. As a result, in the embodiments of FIGS. 7A and 7B, the electrode elements E1 to E9 are not all electrically connected to the same graphite sheet 70. Therefore, electricity cannot flow from one graphite sheet 20 to another graphite sheet 20. That is, different signals can be applied to separate groups of electrode elements.

[0078] The embodiments of FIGS. 7A and 7B further include a layer 15 of skin-compatible conductive material disposed on the front side of each graphite sheet (e.g., on the front surface of each graphite sheet as shown).

[0079] In particular, unlike the embodiments of FIGS. 4A and 4B, which include a metal layer disposed behind a dielectric layer in which each of the electrode elements E1 to E9 is arranged to be in electrical contact with a respective one of the graphite sheets in turn, in the embodiments of FIGS. 7A and 7B, the electrode elements E1 to E9 do not include a dielectric layer. Instead, the electrode elements E1 to E9 in the embodiments of FIGS. 7A and 7B have a metal layer arranged to be in electrical contact with each respective graphite sheet 20 without an intervening dielectric layer. For example, in the embodiments shown in FIGS. 7A and 7B, each of the electrode elements E1 to E3 is arranged to be in electrical contact with the first graphite sheet 20 (i.e., the left sheet) and has a metal layer located behind it, and each of the electrode elements E4 to E6 is arranged to be in electrical contact with the second graphite sheet 20 (i.e., the central sheet) and has a metal layer located behind it, and each of the electrode elements E7 to E9 is arranged to be in electrical contact with the third graphite sheet 20 (i.e., the right sheet) and has a metal layer located behind it.

[0080] In the illustrated embodiment, the electrical contact between each metal layer of the electrode elements E1 to E9 and each respective graphite sheet 20 is made using a conductive adhesive layer. However, in an alternative embodiment, the electrical contact between each metal layer of the electrode elements E1 to E9 and each respective graphite sheet 20 can be made using another approach (e.g., a conductive gel layer such as a hydrogel).

[0081] Similarly, the embodiments of FIGS. 7A and 7B also include a support 30 having an adhesive backing, similar to the support 30 described above in connection with the embodiments of FIGS. 4A and 4B.

[0082] In the embodiments of FIGS. 7A and 7B, the electrical connection to the electrode elements E1 to E9 may be performed using various approaches including an independent element approach and a grouped element approach, and the approaches for establishing the electrical connection described above in connection with FIGS. 5 and 6 may be used in the embodiments of FIGS. 7A and 7B (however, the graphite sheet is not a dielectric layer and is electrically connected to each metal layer of the electrode elements E1 to E9).

[0083] In the embodiments described in FIGS. 4 to 7, a plurality of electrode elements are arranged to be in electrical contact with each graphite sheet. However, in an alternative embodiment, the number of anisotropic conductive material sheets (e.g., graphite sheets) may be increased according to the number of electrode elements, and in this case, as shown in FIG. 8, only a single electrode element is arranged to be in electrical contact with any given anisotropic conductive material layer. In yet another embodiment (not shown), a plurality of electrode elements are arranged to be in electrical contact with some of the anisotropic conductive material sheets, and only a single electrode element is arranged to be in electrical contact with each of the remaining anisotropic conductive material sheets. The form of graphite described above in connection with FIGS. 4A and 4B may be used in these embodiments, or a non-graphite anisotropic conductive material may be used instead of graphite.

[0084] The embodiment of FIG. 8 and the alternative embodiments described in the previous paragraph may be implemented using capacitive-coupled electrode elements or non-capacitive-coupled electrode elements. When the electrode elements are capacitive-coupled, the electrical connection between any given electrode elements E1 to E9 and the respective graphite sheets 20 is established between the dielectric layer of the electrode elements E1 to E9 and the respective graphite sheets 20 (e.g., as described above in connection with FIGS. 4A and 4B). Alternatively, when the electrode elements are not capacitive-coupled, the electrical connection between any given electrode elements E1 to E9 and the respective graphite sheets 20 is established between the metal layer of the electrode elements E1 to E9 and the respective graphite sheets 20 (e.g., as described above in connection with FIGS. 7A and 7B).

[0085] In the embodiment of FIG. 8, strips 25 of electrically insulating and thermally conductive material are disposed between the graphite sheets 20. The structure and shape of these strips 25 of material may be the same as those described above in connection with FIGS. 4A and 4B, and these strips 25 of material are arranged to be in thermal connection with any adjacent graphite sheet 20. The purpose of these strips 25 of electrically insulating and thermally conductive material is to spread the heat of any graphite sheet 20 that is at the highest temperature to the adjacent graphite sheets, thereby reducing the temperature of the hottest point of the entire electrode assembly. Note that the strips 25 of material are electrically insulated and thus electrically insulate the adjacent graphite sheets 20 from each other. As a result, all of the electrode elements E1 - E9 in this embodiment of FIG. 8 are electrically insulated from each other. Therefore, electricity does not flow from one graphite sheet 20 to another graphite sheet 20, that is, different signals can be applied to the individual electrode elements. As described above, the electrode assembly may be fixed to the human body at a predetermined position using an adhesive backing similar to the support 30 described above in connection with the embodiments of FIGS. 4A, 4B, 7A, and 7B.

[0086] When the electrode assembly is configured as shown in FIG. 8 and a plurality of electrode assemblies are arranged on the opposite side of the target region, the electrode assembly is used to perform electrical impedance tomography (EIT) and impedance tomography of the target region may be performed within a device designed for both purposes of treating a medical condition by TT field therapy characterized by temperature management of the array. Performing EIT using a transducer array is described in U.S. Patent Application No. 17 / 710,041 (filing date: March 31, 2022), which is incorporated herein by reference.

[0087] For example, when each electrode assembly includes N electrode elements (N is at least 4), this can be achieved by continuously measuring the impedance between each of the N electrode elements positioned on one side of the target region and each of the N electrode elements positioned on the other side of the target region using a suitable switching circuit and impedance measurement circuit, and a total of N 2 measurement values can be obtained. Next, these impedance measurement values are sent to a backpropagation algorithm to generate an impedance map of the space existing between the electrode assemblies. This impedance map, or a series of such maps obtained over a certain period, is continuously used to formulate a treatment plan, modify a previously formulated treatment plan, or monitor the progression (development) or regression (shrinkage) of one or more cancers, tumors, or metastases during the process of extended TT field treatment and after the placement of the transducer array according to the treatment.

[0088] In some embodiments, in impedance measurement, only a subset of the electrode elements arranged on the subject's body is used. For example, when a pair of 5×5 electrode element arrays are arranged on opposite sides of the target region of the subject's body, the impedance between each of the N = 16 electrode elements positioned on one side of the target region and each of the M = 21 electrode elements positioned on the other side of the target region is continuously measured using a switching circuit and impedance measurement circuit, and a total of N×M measurement results can be obtained. Next, these impedance measurement values are sent to a backpropagation algorithm to generate an impedance map of the space existing between the N electrode assemblies and the M electrode assemblies.

[0089] After generating the treatment plan, an alternating voltage is applied between most (or at least a plurality) of the electrode elements on one side of the target region and most (or at least a plurality) of the electrode elements on the other side of the target region, thereby inducing an alternating electric field in the target region.

[0090] In the embodiments described above in connection with FIGS. 4 through 8, all of the anisotropic conductive material sheets 20 (e.g., graphite sheets) in any given embodiment are of substantially the same size, and those anisotropic conductive material sheets 20 contact the same number of electrode elements (the number of electrode elements is 3 in FIGS. 4 through, or the number of electrode elements is 1 in FIG. 8). However, in an alternative embodiment (not shown), the size of the anisotropic conductive material sheet 20 may be varied within a single electrode assembly, and / or the number of electrode elements contacting any given anisotropic conductive material sheet 20 may be varied. For example, some of the anisotropic conductive material sheets 20 can contact only a single electrode element, and other anisotropic conductive material sheets 20 can contact two or more electrode elements. In another example, some of the anisotropic conductive material sheets 20 can contact only a single electrode element, and other anisotropic conductive material sheets 20 can contact three or more electrode elements.

[0091] The headings are provided for convenience only and should not be construed as limiting the invention in any way. Embodiments shown in any heading or any part of the present disclosure can be combined with embodiments shown in the same or any other heading or other part of the present disclosure.

[0092] Although the present invention has been disclosed with reference to specific embodiments, many modifications, changes, and variations to the described embodiments are possible without departing from the scope and scope of the invention as defined in the appended claims. Accordingly, the present invention is not intended to be limited to the described embodiments, but rather is intended to have the full scope defined by the language of the claims and their equivalents.

Claims

1. An electrode assembly comprising: a first sheet of anisotropic conductive material having a front side and a front face and a rear side and a rear face; one or more first electrode elements, each arranged to be in electrical contact with the first sheet; a second sheet of anisotropic conductive material having a front side and a front face and a rear side and a rear face, the second sheet of anisotropic conductive material being arranged adjacent to the first sheet without contacting the first sheet; one or more second electrode elements, each arranged to be in electrical contact with the second sheet; a first strip of electrically insulating and thermally conductive material disposed between the first sheet and the second sheet and positioned to be in thermal contact with both the first sheet and the second sheet.

2. The electrode assembly according to claim 1, wherein the first strip of material comprises coated graphite.

3. The electrode assembly according to claim 1, wherein the width of the first strip of material is less than 2 mm.

4. The electrode assembly according to claim 1, wherein the first sheet comprises a synthetic graphite sheet, pyrolytic graphite, a graphitized polymer film, or a graphite foil made from compressed high-purity exfoliated mineral graphite, and the second sheet comprises a synthetic graphite sheet, pyrolytic graphite, a graphitized polymer film, or a graphite foil made from compressed high-purity exfoliated mineral graphite.

5. The electrode assembly according to claim 1, further comprising a first layer of skin-compatible conductive material disposed on the front side of the first sheet and a second layer of skin-compatible conductive material disposed on the front side of the second sheet.

6. There are at least two first electrode elements, each of the first electrode elements comprising a first metal layer and a first dielectric layer disposed on the first metal layer, each of the first dielectric layers being arranged to be in electrical contact with the first sheet and positioned behind the first sheet. There are at least two first electrode elements, each of the first electrode elements comprising a first metal layer and a first dielectric layer disposed on the first metal layer, each of the first dielectric layers being arranged to be in electrical contact with the first sheet and positioned behind the first sheet. There are at least two second electrode elements, each of the second electrode elements including a second metal layer and a second dielectric layer disposed on the second metal layer, each of the second dielectric layers being disposed to be in electrical contact with the second sheet and located behind the second sheet, the electrode assembly according to claim 1.

7. Each of the first dielectric layers and each of the second dielectric layers includes a polymer layer having a dielectric constant of at least 10, the electrode assembly according to claim 6.

8. The electrical contact between each of the first dielectric layers and the first sheet is made using a first layer of a conductive gel or a conductive adhesive, The electrical contact between each of the second dielectric layers and the second sheet is made using a second layer of a conductive gel or a conductive adhesive, the electrode assembly according to claim 6.

9. There are at least two first electrode elements, each of the first electrode elements including a first metal layer disposed to be in electrical contact with the first sheet, There are at least two second electrode elements, each of the second electrode elements including a second metal layer disposed to be in electrical contact with the second sheet, the electrode assembly according to claim 1.

10. There are at least two first electrode elements and at least two second electrode elements, the electrode assembly comprising a plurality of first metal conductors, each disposed to be in electrical contact with only one of the first electrode elements, a plurality of second metal conductors, each disposed to be in electrical contact with only one of the second electrode elements, the electrode assembly according to claim 1.

11. There are at least two first electrode elements and at least two second electrode elements, the electrode assembly comprising at least one first metal conductor disposed to be electrically connected to all of the first electrode elements, at least one second metal conductor disposed to be electrically connected to all of the second electrode elements, the electrode assembly according to claim 1.

12. A coil, wherein energy from a conductor power supply is bypassed by the coil and locally stored in a conductor, and is reused to power a controller, a circuit, or means for generating digital data related to temperature measurement, and further comprising the coil, the electrode assembly according to claim 1.

13. There are at least two first electrode elements and at least two second electrode elements, and the electrode assembly A third sheet of anisotropic conductive material having a front side and a front surface and a rear side and a rear surface, disposed adjacent to the second sheet without contacting the second sheet and without contacting the first sheet, a third sheet; A plurality of third electrode elements, each arranged to be in electrical contact with the third sheet, third electrode elements; A second strip of electrically insulating and thermally conductive material disposed between the second sheet and the third sheet, positioned to be in thermal contact with both the second sheet and the third sheet, further comprising the electrode assembly according to claim 1.

14. A plurality of first metal conductors, each arranged to be in electrical contact with only one of the first electrode elements, first metal conductors; A plurality of second metal conductors, each arranged to be in electrical contact with only one of the second electrode elements, second metal conductors; A plurality of third metal conductors, each arranged to be in electrical contact with only one of the third electrode elements, further comprising the electrode assembly according to claim 13.

15. A first layer of skin-compatible conductive material disposed on the front side of the first sheet; A second layer of skin-compatible conductive material disposed on the front side of the second sheet; A third layer of skin-compatible conductive material disposed on the front side of the third sheet, further comprising The first strip of the material includes coated graphite; The second strip of the material includes coated graphite, the electrode assembly according to claim 13.

16. A method for formulating a treatment plan for a target area of a subject's body using an alternating electric field, Positioning a first set of N electrode elements on a first side of the target region on or within the body of the subject, wherein each of the N electrode elements is arranged to be in electrical contact with an anisotropic conductive material sheet, and N is at least 4; Positioning a second set of M electrode elements on a second side of the target region on or within the body of the subject, wherein each of the M electrode elements is arranged to be in electrical contact with an anisotropic conductive material sheet, M is at least 4, and the second side faces the first side; Sequentially measuring the impedance or conductance between each of the N electrode elements of the first set and each of the M electrode elements of the second set during a first time period; Calculating a first impedance or conductance at each of at least 27 voxels corresponding to positions between the first set of N electrode elements and the second set of M electrode elements based on the measurement of the impedance or conductance; Formulating a plan for treating the target region with an alternating electric field based on the first impedance or conductance of the voxels. A method comprising the steps of:

17. The method according to claim 16, wherein a plurality of strips of electrically insulating and thermally conductive material are disposed between adjacent sheets of anisotropic conductive material and positioned to be in thermal contact with the adjacent sheets.

18. The method according to claim 17, wherein the sheets of anisotropic conductive material each comprise a synthetic graphite sheet, pyrolytic graphite, a graphitized polymer film, or a graphite foil made from compressed high-purity exfoliated mineral graphite.

19. The method according to claim 17, further comprising applying an alternating voltage between a plurality of electrode elements in the first set and a plurality of electrode elements in the second set to induce an electric field in the target region subsequent to formulating the plan.

20. The method according to claim 17, wherein the plan includes creating a recommendation to move at least one set of electrode elements to a different position on or within the body of the subject.

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