Isotropic non-aqueous electrode sensing material

Abstract

Disclosed herein is a non-aqueous isotropic conductive signal receiving composite comprising a continuous conductive material having a top surface and a bottom surface, both surfaces substantially covered by a dielectric polymer material, the dielectric polymer having a polar material within.

Description

[0001] priority

[0002] This application claims priority to U.S. Provisional Patent Application No. 62 / 994,558, filed March 25, 2020, the disclosure of which is incorporated herein by reference. Background Technology

[0003] This invention relates generally to sensor systems, and more particularly to sensor systems for detecting and transmitting electrical signals.

[0004] Traditionally, various forms of ion-conducting media (such as hydrogels) have been used to acquire biomedical signals, such as electrocardiogram (ECG or EKG) signals, surface electromyography (sEMG) signals, and electrical activity of the skin (EDA) signals. These aqueous signal-capturing complexes typically rely on elements dissolved in the aqueous material (such as salts) to achieve ion conduction. Salts such as sodium chloride or potassium chloride dissolve readily in aqueous media, and their ions dissociate (separate into positive and negative ions). These dissociated ions can then carry an electric current or signal. For this reason, salts have long been added to water, which can then be added to polymer and elastomer materials to provide good conductivity.

[0005] For example, U.S. Patent No. 6,121,508 discloses a pressure-sensitive adhesive hydrogel for biomedical electrodes. The disclosed hydrogel material comprises at least water, potassium chloride, and polyethylene glycol, and is conductive according to the disclosure. U.S. Patent No. 5,800,685 also discloses a conductive adhesive hydrogel comprising water, salt, an initiator or catalyst, and a crosslinking agent. However, the use of such hydrogels typically requires the use of a conductive, low-resistivity surface on one side of the hydrogel (away from the patient) capable of receiving ionic conductive charges, such as silver / silver chloride, which is relatively expensive.

[0006] While these hydrogels / adhesives can exhibit good electrical conductivity, they typically only possess ordinary adhesive properties. Another drawback is that the conductivity varies with water content, such as due to evaporation, requiring the hydrogel to be kept in a sealed environment before use, after which it can only be used for a limited time due to evaporation. Therefore, the water content in such composites significantly affects electrical performance. This poses a challenge to the shelf life and storage environment of aqueous-based electrodes, as even sealed packaging can experience some evaporation over time.

[0007] Alternative technologies have been developed as taught in U.S. Patents 7,651,638, 8,788,009, 8,792,957, 8,673,184, 9,818,499, and 9,775,235. Some of these alternative technologies are based in part on non-aqueous base systems using organic polar compounds substantially dispersed in a dielectric organic polymer. Depending on the dielectric polymer chosen, such composites can also be used as pressure-sensitive adhesives (PSAs) for easy placement on a patient. Furthermore, by carefully selecting the PSA, the level of adhesion can be tuned from long-term adhesion to the skin to less intense adhesion in newborns or elderly patients. The combination of polar materials with polymeric dielectric materials needs to avoid phase separation that occurs over time and with temperature, as well as when subjected to particularly high humidity.

[0008] The design of conductive PSAs has long been challenging, at least because adhesive strength and flexibility typically decrease with increasing conductive material presence. Materials often used (as additives) to provide good conductivity are generally less flexible and inhibit adhesion. A conventional method for preparing conductive coatings involves filling a polymeric material with conductive particles such as graphite, silver, or copper, followed by coating, drying, and curing with a polymeric adhesive. In these cases, the concentration of conductive particles is such that a conductive network is formed when each particle is in physical contact with at least one other adjacent particle. In this way, conductive pathways are provided through the composite.

[0009] However, for pressure-sensitive adhesives, if the particle concentration is high enough to form a network that keeps the particles in contact, the polymer (e.g., elastomer) system of the PSA component is unlikely to be present at a sufficiently high concentration to flow out and achieve adequate surface-to-surface contact between the substrate and the electrode, thus acting as an adhesive. Conversely, if the concentration of the PSA component is sufficient to achieve adequate surface contact with the substrate, the PSA will have to interrupt adjacent conductive particles, thereby disrupting the particle-to-particle contact and adversely affecting conductivity.

[0010] Another type of conductive PSA comprises conductive spherical particles with a diameter equal to or greater than the thickness of the PSA. In this way, signals or currents can be transmitted along the surface of the particles, thereby providing anisotropic current flow in the thickness dimension of the adhesive. However, the continuity of the adhesive may be affected due to the volume of the large spherical particles.

[0011] U.S. Patent No. 5,082,595 discloses a conductive voltage-sensitive adhesive comprising carbon particles. This conductive adhesive is prepared according to the disclosure by incorporating a black filler (carbon) into the voltage-sensitive adhesive to impart conductivity, but at a sufficiently low concentration to avoid adversely affecting the adhesive's physical properties (e.g., tackiness). Specifically, the patent states that a slurry of carbon black in an organic solvent is formed under gentle mixing or stirring without high shear, thereby forming a carbon structure. The mixture can then be incorporated into the adhesive. However, such composites may not provide sufficient adhesion and conductivity in certain applications. Such composites may also include regions with relatively higher or lower concentrations of conductive material. Some conductive polymers and elastomers include conductive particles at concentrations within the polymer or elastomer, which may therefore exhibit inconsistent electrical properties on the material surface.

[0012] Therefore, there is still a need for a composite material that can be used as a conductive polymer material, which provides conductivity without compromising the desired properties of the polymer material. In addition, there is a need for a conductive polymer material that provides consistent electrical properties. Summary of the Invention

[0013] According to one aspect, the present invention provides a non-aqueous isotropic conductive signal receiving composite comprising a continuous conductive material having a top surface and a bottom surface, both surfaces being substantially covered by a dielectric polymer material having a polar material within the dielectric polymer.

[0014] According to another aspect, the present invention provides a method for manufacturing a non-hydrogel isotropic conductive signal receiving material. The method includes providing a continuous conductive material, both sides of which are substantially coated with a mixture of a dielectric polymer and a polar material.

[0015] According to another aspect, the present invention provides a non-aqueous isotropic conductive signal receiving composite comprising a continuous conductive material having a top surface and a bottom surface, both the top surface and the bottom surface comprising a polymeric material thereon, the polymeric material comprising polar substituents attached to a polymer of the polymeric material.

[0016] According to another aspect, the present invention provides a signal receiving material comprising a polar material distributed within a polymeric material and a conductive material distributed within the polymeric material, wherein the conductive material extends in both the length and width directions, and both are significantly larger than the thickness direction of the signal receiving material.

[0017] According to another embodiment, the present invention provides a signal receiving fiber material comprising a polar material distributed within a polymeric material and a conductive material distributed within the polymeric material, wherein the conductive material is substantially coated with the polymeric material and the polar material is distributed therein. Attached Figure Description

[0018] The following description can be further understood in conjunction with the accompanying drawings, in which:

[0019] Figure 1 The diagram shown is a schematic illustration of a composite material of one aspect of the present invention.

[0020] Figure 2 The image shows the application to the object. Figure 1 A schematic diagram of the complex;

[0021] Figure 3 The image shows the application. Figure 2 A schematic top view of the electrodes of the composite;

[0022] Figure 4 The image shows the application to the object. Figure 3 A schematic diagram of a pair of electrodes;

[0023] Figure 5A and 5B The composite material shown is in the presence of charge from an alternating electric field, representing one aspect of the present invention. Figure 5A ) and subsequently not exist ( Figure 5B A schematic diagram illustrating the following situation;

[0024] Figure 6 The diagram shown is a schematic illustration of a composite material of another aspect of the present invention, comprising a continuous conductive material.

[0025] Figure 7 As shown Figure 6 A schematic diagram of the complex in the presence of an alternating electric field;

[0026] Figure 8 The diagram illustrates a continuous conductive material in the form of a solid film, representing one aspect of the present invention.

[0027] Figure 9 The diagram shown is a schematic illustration of a continuous conductive material in the form of a braided material, according to one aspect of the present invention.

[0028] Figure 10 The diagram illustrates a continuous conductive material in the form of a nonwoven mesh material, according to one aspect of the present invention.

[0029] Figure 11 The diagram illustrates a continuous conductive material in the form of a disordered material, according to one aspect of the present invention.

[0030] Figure 12 The diagram shows a schematic representation of the impedance test results for a composite material that does not contain polar materials.

[0031] Figure 13 The diagram shows a schematic representation of the impedance test results for a composite material with polarity.

[0032] Figure 14 The diagram shows a schematic representation of the impedance test results for a composite material containing both polar and conductive materials.

[0033] Figure 15 The diagram shows a schematic representation of the skin impedance test results for electrodes containing silver macrode.

[0034] Figure 16 The diagram shows a schematic representation of the skin impedance test results for a composite electrode comprising conductive and polar materials.

[0035] Figure 17 The diagram shows a schematic representation of the skin impedance test results for a composite electrode that includes both conductive and non-polar materials.

[0036] Figure 18 The following is a description of the use of... Figure 15 A schematic diagram of the ECG / EKG test results of the electrode;

[0037] Figure 19 The following is a description of the use of... Figure 16 A schematic diagram of the ECG / EKG test results of the composite electrode;

[0038] Figure 20 The following is a description of the use of... Figure 17 A schematic diagram of the ECG / EKG test results of the composite electrode;

[0039] Figure 21 The diagram shows a schematic representation of the electrode-to-skin impedance using ECG snap-on electrodes with and without polar materials, as well as a test control electrode.

[0040] Figure 22 The diagram shows a schematic illustration of a composite material that includes carbon fiber as a conductive material.

[0041] Figure 23 The following is included Figure 22 A schematic top view of the electrodes of the composite;

[0042] Figures 24A-24C The diagram shown is a schematic partial view of a signal receiving composite material, which includes a woven material ( Figure 24A ), non-woven materials ( Figure 24B ) and felt pads ( Figure 24C );and

[0043] Figure 25 The diagram shows a signal comparison of transcutaneous electrical nerve stimulation (TENS) tests in a complex of one aspect of the invention and in a complex containing silver macrode.

[0044] The accompanying drawings are for illustrative purposes only. Invention Details

[0046] Various aspects of the present invention provide a signal receiving composite comprising a non-aqueous dielectric material and a polar material. The composite also includes a conductive material within the non-aqueous dielectric material, which, according to some aspects, extends at least in an elongation direction at least twice the thickness of the signal receiving composite. According to various other aspects, the conductive material includes elements extending in the elongation direction, wherein the elongation direction is at least as long as the thickness of the signal receiving composite. According to other aspects, the conductive material includes elements generally extending in the elongation direction, wherein the conductive material itself is not straight, but is formed of loose or braided or non-woven or entangled or felted fiber bundles surrounded by the signal receiving composite. According to other aspects, the conductive material includes metal foil, mesh material, loosely woven fabric material, or woven or non-woven metal wool material.

[0047] Figure 1 A composite of one aspect of the invention is shown at position 10, comprising a dielectric material 12 and a pair of release liner pads 14, 15 on either side thereof. The dielectric material 12 includes a polar material 16 therein and a conductive material 18 (e.g., referred to herein as a curtain material). Figure 1 As shown, according to one aspect of the invention, a conductive material (e.g., long-stranded carbon fiber) can be randomly distributed within a dielectric material. (Reference) Figure 2 This allows for the removal of the peeling pads 14 and 15 and the application of conductive electrode connections 22 to one side of the composite 20. When the other side of the composite 20 is applied to an object (e.g., a patient), an alternating electrical signal (denoted as 24) can be presented to the composite (denoted as 24). Note that the electrical signal does not need to be located directly below the electrode connections 22. Figure 3 The diagram shows a top view of the composite 20, in which connection 22 is coupled to lead 26. The dielectric material 12 preferably has a sufficiently low surface energy to wet the surface of the conductive material 18, resulting in the surface of the conductive material (even the exposed ends of material 18 at their exposed surfaces) being covered by the dielectric material 12. Therefore, according to one aspect of the invention, even the electrode connection 22 does not directly contact any conductive material 18.

[0048] According to a specific aspect of the invention, polar materials can be dispersed within dielectric materials and can be, for example, (but not limited to) quaternary ammonium salts. A variety of such materials are commercially available, primarily for use as cationic surfactants or antistatic additives and in certain cosmetic applications. The diversity of molecular variations in this family of compounds increases the possibility of finding a compatible pair with a given dielectric polymer, which will be discussed in more detail below. Such quaternary ammonium salts can be represented as:

[0049]

[0050] Wherein, R = H or some carbon-based moiety, wherein any of the R groups can be the same or different. For example, the polar material can be Arquad HTL8-MS quaternary ammonium salt sold by AkzoNobel Surfactants, Inc., Chicago, Illinois.

[0051] Polymer materials can be, for example, but not limited to, acrylic adhesives, and can be represented as follows:

[0052]

[0053] Wherein, R can vary and can be any of ethyl, butyl, 2-ethylhexyl, or other organic moieties, and n is the number of repeating units. For example, the polymeric material can be FLEXCON V95 pressure-sensitive adhesive sold by FLEXCON Ltd. in Spencer, Massachusetts.

[0054] One aim in selecting the combination of binder and polar material is that both materials exhibit a mutual attraction very similar to the attraction of each material to its own molecules. This results in the polar material being uniformly dispersed in the binder. The suitability of the combination of polymer and polar material can be determined through the following procedure. First, the polar material is combined with the polymer at approximately five different concentrations (typically between approximately 5% to approximately 45% by weight). The binder-salt composite is then pulled onto a release liner (approximately 1.5 mils) and allowed to dry and cure. The surface of the composite is then examined after a short period. If the polar material has crystallized or bloomed on the surface, the combination of components is incompatible. Conversely, if the composite is clear, a further compatibility test is required. An exposure test should then be performed on the sample, in which the sample is exposed to 100°F and 95% relative humidity for 3 days. The sample is then examined again to determine whether the polar material has migrated to either surface. If the polar material does not migrate and the composite is transparent, the dielectric constant of the composite is determined and the composite is tested for use as a medical monitoring material.

[0055] Therefore, according to one aspect, polymeric and polar materials are chosen such that they each exhibit a mutual attraction substantially the same as their attraction to themselves. Because of this, the polar material neither aggregates nor frosts the surface of the polymeric material, but remains suspended within it. This contrasts with the use of salts in other applications where they are intended to frost surfaces (to provide a conductive layer along the surface, e.g., for electrostatic discharge) or to chemically react with binder materials (e.g., dissolve). In other words, compatible binder and polar materials are chosen, but those that do not undergo molecular transformations, such as those that occur with NaCl in water. Thus, the molecularly polar material is dispersed within the binder material but does not undergo molecular transformations.

[0056] However, according to other aspects of the invention, the polar material can be selected such that it can be bonded to the polymer of the dielectric material. Furthermore, therefore, when selecting a polymer having the desired hydrophilic / hydrophobic properties (e.g., having a specific R group as described above), the polymer can be further selected to bond the specific polar material. It is advantageous to use a dielectric material comprising a polar material bonded to a polymer of the dielectric material, wherein dissolution or frosting may occur over time. For example, if the polar material has suitable functional groups, such as hydroxyl functional groups, and the adhesive material has carboxyl groups, a reaction may occur in which the polar material is incorporated into the adhesive material to some extent. According to other aspects, if the adhesive material has ester side groups and the polar material has hydroxyl or even carboxyl functional groups, some transesterification may occur again, resulting in polymer chains with linked polar materials.

[0057] For example, a PSA can include cationic substituents on an acrylic copolymer. For instance, FLEXCON's V-19 adhesive (sold by FLEXCON Ltd., Spencer, MA) has cationic substituents on an acrylic copolymer PSA, which can be bonded to polar materials. In one example, such an adhesive is provided with a continuous conductive layer without the addition of polar material. The continuous conductive layer is supplied by Nonwoven Conductive Curtain Product #20353A from Technical Fiber Products, Inc., Schenectady, NY. This example was tested and produced a skin impedance of 53 kΩ. Subsequently, the same adhesive and curtain were supplied with half the normal load of a polar material (such as FC-5000 Ionic Antistatic Material from 3M Ltd.), and the sample had an impedance of 5.2 kΩ. This is an important trade-off; other external considerations such as skin adhesion are important factors in selecting a particular composition, but using cationic or other polar substituents on the polymer material or using a PSA on the non-adhesive layer provides more options for constructing the final signal receiving material (SRM).

[0058] A distinguishing characteristic of polymers with such polar materials as part of their structure is their relative permittivity. For example, FLEXCON's H582 base adhesive has a relative permittivity of 2.0 at 100 Hz; while FLEXCON's V-19 has a relative permittivity of 3.9. The relative permittivity indicates that the polymer can be used as an SRM even when containing continuous layers, but other properties such as compatibility with various skin conditions will play a crucial role in resin selection.

[0059] The test procedure (AAMI EC 12 2015 4.2.2, including 4.2.2.1, 4.2.2.2, 4.2.2.3, 4.2.2.4) that could predict whether non-aqueous SRM could be performed in practical use for ECG testing was identified as skin impedance testing. The skin impedance testing procedure involves applying a first test electrode to the skin of an arm or leg; starting a timer; applying a second test electrode to the skin of the same arm or leg; connecting a voltmeter lead to the test electrode; recording the measurement; and repeating the process for several minutes while recording the results. Reference Figure 4 A pair of such electrodes 30, 32 can be placed close to each other on an object (e.g., arm 34). Each electrode is coupled to connections 36, 38, which are connected to an inductor-capacitor-resistor (LCR) meter used to determine skin impedance.

[0060] According to one aspect of the invention, the non-aqueous composition provided herein does not require bridging or activation to pass through AMMI, and is isotropic according to one aspect of the invention. In one example, the composition comprises a dielectric material (in which a polar compound is substantially dispersed) and a conductive layer (e.g., a fabric, woven or nonwoven carbon fiber, wire mesh, or metal foil material substantially covering the material). The conductive continuous layer comes in various forms, from carbon films, metal foils, and wire meshes to woven and nonwoven fabrics, and has a variety of thicknesses and densities. The properties of the dielectric material can range from pressure-sensitive adhesives (PSAs) to non-adhesive polymer materials.

[0061] The concentration of polar materials can reach up to 45% by weight of their mixture with dielectric polymers. The selection criteria for which polar material to pair with which dielectric polymer are based on compatibility with the aforementioned organic dielectrics. Another property of dielectric polymers in PSAs is that, by correctly selecting polar materials, the material's ability to adhere to the skin can be improved. Given the vast variations in skin surface quality, it is advantageous to use polar materials that complement skin adhesion properties.

[0062] Continuous conductive materials can be introduced through coating, lamination, extrusion, or any method used to introduce continuous or semi-continuous conductive layers into polymeric polar material blends. Furthermore, even higher viscosity thermoplastic non-sticky dielectric polymers are more easily incorporated into SRMs without the need for aligning or activating conductive particles. This can be used in applications related to the use of wearable biosensing electrodes, which are secured in place with wraps, vests, or other such pressure garments.

[0063] According to one aspect, the present invention provides a non-aqueous signal receiving material that is isotropic and comprises, for example, a continuous conductive layer within a dielectric material. The continuous conductive layer can be derived from a conductive film, mesh, or metal foil, or a conductive fabric, which is composed of conductive fibers such as carbon fibers or a non-conductive material having a conductive surface coating. The fabric can be woven, knitted, or nonwoven, but in many examples, the basic principle is to make the resulting continuous conductive layer conductive at least in the larger (X and Y) non-thickness dimensions, and optionally in all (X, Y, Z) dimensions. Isotropicity also facilitates connection to backing electrical contacts. Conversely, anisotropic signal receiving materials use a conductive surface connected to a monitor via a conductive path, wherein the area of ​​the conductive surface is directly related to the amount of signal picked up. Compositions consisting of a dielectric polymer having a polar material distributed therein, and then containing a continuous conductive material within the dielectric polymer, will pass AMMI EC12 2015 without further processing steps such as bridging and activation. It has been found that when it comes to non-aqueous-based signal receiving materials, skin impedance is a better predictor of the function of non-aqueous electrodes than simply passing AAMI.

[0064] The mechanisms for transmitting electrical signals are dynamic, including capacitive coupling and low-impedance conductive materials, such as conductive curtains or other continuous conductive layers, as described herein. References Figure 5A and 5B In one aspect of the invention, the composite 50 includes a polar material 52 distributed within a dielectric material 54 and a conductive material 56 as described above. The thickness d1 of the composite can vary widely depending on various biomedical and non-biomedical applications and can be, for example, as thin as micrometers or as thick as more than an inch, depending on the application. The diameter of the carbon fiber 56 can, for example, be less than 1 micrometer or greater than 50 micrometers, depending on the application. Although the polar material near the signal source 60 (in...) Figure 5A As shown in Figure 58, it will respond to alternating signals, but polar materials not near the signal source will not respond in this way. However, according to one aspect of the invention, conductive material 56 will pick up the signal and distribute it throughout the composite via charge distribution, such as... Figure 5B The arrow in region 62 is shown.

[0065] As described above, a continuous conductive material can comprise a conductive material layer provided as a conductive film (e.g., aluminum or carbon) layer, a woven or nonwoven material layer (e.g., carbon fiber), or a flat pad of a disordered material (again, carbon fiber). Reference Figure 6 Such a conductive material layer can be provided between two dielectric materials, wherein a polar material is distributed. Specifically, composite 70 includes a first dielectric material 72 wherein a polar material 74 is distributed, a second dielectric material 82 wherein a polar material 84 is distributed, and a conductive layer 80 sandwiched between the first dielectric material 72 and the second dielectric material 82. Composite 70 also includes release liner 76, 78 on the exposed surfaces of the composite. The composite (excluding release liner) may have a thickness d2, the first dielectric material 72 may have a thickness d3, the second dielectric material 82 may have a thickness d5, and the conductive layer 80 may have a thickness d4, all suited to specific applications. An advantage of one aspect of the invention is that the composite of the invention is highly versatile in applications requiring multiple thicknesses or other dimensions. Reference Figure 7 When alternating signals are present (e.g., biomedical signals as shown at position 86), certain polar materials (e.g.) Figure 7 (As shown at point 88) will be aligned with the biomedical signal. The charge generated by this alignment will be picked up by the conductive layer 80 and transferred around the composite, resulting in the alignment of the additional polar material 74, such as... Figure 7 As shown. This generated alignment of additional polar material will result in a signal being supplied to electrode 78. Reference Figure 8-11 The conductive layer 80 can be a film 90 (e.g., aluminum or carbon), a metal fabric woven with conductive material 92 (e.g., woven carbon fiber), a nonwoven mesh 94 (e.g., carbon fiber), or a flat pad of disordered material 94 (again, carbon fiber).

[0066] The following examples illustrate composites prepared according to various aspects of the present invention.

[0067] Example 1

[0068] Add 15% dry weight of a polar material, in this example Arquad HTL8-MS, sold by Nouryon Chemicals in the Netherlands, to the organic solvent solution of PSA (FLEXCON H-582, sold by FLEXCON Ltd., Spencer, Massachusetts). Cast the solution onto the release coating side of a 38-micron polyester film. Apply a continuous conductive layer material to this. In this example, the continuous conductive layer is a nonwoven conductive curtain material, product #20352A, 4 g / sm, available from Technical Fiber Products Ltd., Schenectady, New York. Lay the curtain material and press it into the still-wet PSA solution. The composite is then dried. A second sample is then prepared in a similar manner, using the same pressure-sensitive adhesive and the same curtain material, but without any polar material.

[0069] Both samples (one containing a polar material and the other not) and a standard aqueous-based ECG electrode (Silver MactrodePlus, manufactured by GE Healthcare, Marburg, Massachusetts) used as a control reference were tested according to AAMI EC12 2015 4.2.2.1, 4.2.2.4 and 4.2.2.2, 4.2.2.3 and 4.2.2.5, and the aforementioned references for skin impedance testing. Results are as follows... Figure 12-14 As shown, where, Figure 12 The SilverMacrode result is shown at position 100. Figure 13 Results for composites without polar materials (FLEXCON H-582 and Carbon Curtain 20352A, without polar materials) are shown at 102. Figure 14 Results for composites containing polar materials (FLEXCON H-582, polar material (Arquad HTL8-MS), and carbon curtain 20352A) are shown at 104. As shown in the figure, all components that could be tested according to AAMI EC12 2015 passed for each electrode.

[0070] However, when these three samples used the above reference... Figure 4 When the FLEXCON skin impedance test was performed, the results were inconsistent. The Silver Mactrode and samples containing both conductive and polar materials passed easily. Samples with only conductive material added to the adhesive without the polar material resulted in skin impedance 8 times higher than samples with added polar material. In particular, Figure 15 The skin impedance test results of Silver Macrode are shown at position 106. Figure 16 The skin impedance test results for the composite material with polar materials are shown at 108. Figure 17The skin impedance test results of the complex without polar materials are shown at 110, indicating that the impedance increases significantly when the polar materials are omitted.

[0071] These three electrodes were also tested on a MAC 1200G ECG / EKG machine from GE Healthcare. For the Silver Macrode electrode, results showed... Figure 18 At position 120, for composites without polar materials, the results show... Figure 19 At position 122, while for composites with polar materials, the results show... Figure 20 At position 124. Clearly, a polar material is required because... Figure 19 The absence of detected ECG signal indicates that the composite material with polarity provides excellent ECG signal data.

[0072] Due to the isotropic conductivity of the composite, post-processing of the signal receiving material with continuous conductive and polar materials is highly efficient. Apart from the elimination of the need for bridging or activation, the substrate to which the signal receiving material is attached does not require its entire surface (in contact with the signal receiving material) to be conductive.

[0073] For example, a signal receiving material consisting of a dielectric polymer (H-582, sold by FLEXCON Ltd.) and 30% by weight of a polar material (ionic liquid antistatic agent FC-5000, a salt of alkoxylated quaternary alkylammonium fluoroalkyl sulfonyl imide, sold by 3M Ltd., St. Paul, Minnesota) and a conductive material (Optiveil 20352A carbon fiber material, sold by British Technical Fiber Products Ltd.) was applied to a supporting substrate (FLEXMARK NWP nonwoven polyester, sold by FLEXCON Ltd., Spencer, Massachusetts). A second sample was prepared similarly, with a conductive outer coating (EXV-461 conductive coating, sold by FLEXCON Ltd.) added to the same side of the supporting substrate where the signal receiving material was added; this conductive coating is necessary for anisotropic signal receiving materials in the prior art.

[0074] For both samples, ECG snap-on electrodes were installed and skin impedance was measured. An aqueous electrode material (Skintact FS-40, sold by Leonard Long Ltd., Inverness, Florida, USA) was also tested as a control. Reference Figure 21No significant difference in electrode impedance to skin was found between the aqueous electrode control and electrodes with or without a conductive coating on a support substrate beneath the signal receiving material (shown at 130) or with a conductive coating (shown at 132), or the Skintact electrode (shown at 134). This means that almost no changes to subsequent manufacturing steps are required between the current product and the isotropic conductive non-aqueous signal receiving material. Another advantage is that in most aqueous snap-on electrodes, the hydrogel is surrounded by an adhesive to secure the electrode to the skin. According to one aspect of the invention, the signal receiving material is also an adhesive.

[0075] Another advantage of using a continuous conductive layer is that, since there is no activation step, the substrate adhesive does not need to have a high viscosity (over 1 million cps) to maintain the “Z” pillars formed by electrophoresis. This allows for other lower viscosity PSAs, such as radiation-curable PSAs. Using a low-viscosity radiation-curable PSA with conductive particles would require a fairly strong electric field for materials such as carbon, or a magnetic field if ferromagnetic particles are used. In either case, an anisotropic signal-receiving material is produced. When using a screen with a radiation-curable PSA, the limiting factor is curing, because particle alignment is not required and the resulting product is isotropic.

[0076] Example 2

[0077] Five parts of a polar material (Arquad HTL8-MS, sold by Nouryon Chemicals, Netherlands) were added to 100 parts of adhesive (Rad Bond 12PS 12L V FB adhesive sold by Actega North America, Chicago, Illinois). The mixture was applied to a carbon curtain 20352A sold by Technical Fiber Products, Inc., Schenectady, New York, supported on a 90-poly(PFW) release liner sold by FLEXCON, Inc. Samples thus constructed were cured under UV light and then laminated onto a 50-micron polyester with a conductive carbon coating. A second set of samples was prepared similarly, but this time without the addition of the polar material (Arquad HTL8-MS).

[0078] Both sets of samples were tested by placing them on conductive carbon-filled acrylic. A 50-micron polyester substrate coated with a conductive layer was brought into contact with a conductive island placed on the opposite side of the SRM and tested. The electrode-to-electrode impedance results were as follows: 1.5 kΩ with polar material and 420 kΩ without polar material. Next, the skin impedance of the samples was tested: 4 kΩ for the control (silver mactrode), 19 kΩ for the sample with polar material (Arquad), and 380 kΩ for the sample without polar material (Arquad).

[0079] Note that although electrode-to-electrode impedance measurements show that the sample without Arquad (polar material) has a lower impedance than the electrode with Arquad, skin impedance tests show (as in the previous examples) the opposite result. Similar composites were also fabricated using aluminum foil, metal mesh materials, and conductive woven fabrics, all exhibiting the same isotropic properties as the nonwoven curtain material.

[0080] Example 3

[0081] The third embodiment involves using a metal foil (e.g., aluminum foil) to explore the maximum thickness of electrodes that can be fabricated. The flat aluminum foil avoids the irregular contours of fabrics, including woven and nonwoven materials. A mixture of a polar compound (FC-5000, sold by 3M) and a pressure-sensitive adhesive (PSAH-582, sold by FLEXCON) is applied to a 0.0007-inch layer of aluminum foil. This mixture is coated onto the aluminum foil to form a 0.0002-inch coating deposition (dried) and covered with a silicone-coated polyester to protect the adhesive composition. A second coating of adhesive / polar material is applied to the other side of the aluminum / PSA / protective pad composite, again forming a 0.0002-inch dried deposition. The thickness (Z) and length and width (X, Y) dimensions of the composite sample are tested. The average impedance in the Z direction is 540 ohms, and the average impedance in the X, Y planes is 590 ohms. These values ​​are well within the definition of electrical isotropy.

[0082] Depending on other aspects, the continuous polymer medium may not be a pressure-sensitive adhesive (for example, it can be a substantially non-sticky material). Such electrodes are typically used in conjunction with pressure jackets. In many, but not all, cases, the non-stick electrode is permanently attached to the pressure jacket, thus making durability against repeated washing a standard requirement for many potential applications. Therefore, the water solubility of any polar material in the continuous polymer matrix should be minimized. Another consideration is that the moisture permeability of the electrode should minimize sweat buildup between the skin and the electrode.

[0083] In another embodiment, a composite is formed in which a continuous, substantially non-adhesive layer of thermoplastic polyurethane (TPU) (H-501, sold by FLEXCON Ltd.) contains 15% by dry weight of a polar material (FC-5000, sold by 3M Ltd.) and a curtain material (Optiveil 20352A, sold by Technical Fiber Products Ltd.). As in the embodiment using PSA as the dielectric continuity layer, a solution of TPU resin and FC5000 is applied to a peelable carrier film, and the composite is then dried using a curtain. Test strips are then prepared and pressure is applied to the skin using a 60g load for skin impedance testing. A skin impedance of 40 kΩ is obtained.

[0084] To attach non-adhesive biosignal sensing materials to a compressed fabric, TPU resin can adhere to multiple fabric layers, requiring only heating of the uncoated side of the peelable carrier. Bonding can be formed due to the compatibility of the non-adhesive layer and the outer jacket. In cases where the fabric is incompatible with the continuous layers in the sensor, an additional layer of material needs to be added to the SRM to promote bonding.

[0085] According to other aspects of the invention, the signal receiving composite can be used in a variety of applications, including biomedical and other applications, when it is necessary to transmit a signal from one region to another. For example, some applications may not even require the polymeric material to be an adhesive. Furthermore, it is not necessary to provide the composite of the invention as a pad or a conventional electrode.

[0086] For example, according to other aspects of the invention, the conductive material may include carbon fibers, and the carbon fibers may be coated with a dielectric material comprising a polar material distributed therein, as described above. For example, Figure 22 A signal receiving composite 150 is shown, comprising carbon fibers as a conductive material 152 and a dielectric material coating 158 in which a polar material 156 is distributed. Figure 23 As shown, dielectric material 154 (including dielectric material 158 and polar material 156) surrounds conductive material fiber 152.

[0087] Further reference Figure 24A Such a signal-receiving composite 150 can be used to form a woven composite 160 by weaving together multiple such coated fibers 150. Similarly, as Figure 24B As shown, this type of signal receiving composite 150 can be used to form a nonwoven composite 162 by combining multiple such coated fibers 150 in a nonwoven manner. Figure 24C As shown, such signal receiving composite 150 can be used to form entangled or felted composite 164 by combining multiple such coated fibers 150 in an entangled or felted manner.

[0088] Other applications of the isotropic SRM materials of various aspects of the present invention involve delivering electrical pulses to a subject. For example, the use of transcutaneous electrical nerve stimulation (TENS) can be used for a variety of applications, including pain relief. TENS units deliver small electrical pulses to a patient's skin via electrodes; these pulses stimulate the body to produce endorphins, which can (in certain specific applications) alleviate pain.

[0089] An example of such a compound includes one with FLX068983OMNI-WAVE. TM FLEXCON dry electrodes for TT 200 and BLACKH-502, which are compatible with a Silver Mactrode... TMExamples of Plus hydrogel electrodes are provided together. Test equipment includes the iReliev iRenew as a signal source. TM The test involves a TENS+EMS system (#ET-7070 model) and a Tektronix MDO3024 oscilloscope as a signal monitor, along with clip-on leads. The test method for the electrode pair assembly involves removing the protective release liner from the adhesive side of each of the two electrodes. The adhesive layers of each electrode are then placed together to form the electrode pair. The test method for electrode signal testing involves connecting the electrode pair to the measuring device. Signal measurements are collected two minutes after electrode pair assembly. The test method for electrode impedance testing involves connecting the electrode pair to an LCR meter. Impedance measurements are performed at 10 Hz and 20 mV two minutes after electrode pair assembly.

[0090] The measured values ​​are as follows. For the electrode pair impedance, Silver Mactrode... TM Plus produced an impedance of 444 ohms, while the SRM complex ( OMNI-WAVE TM H-502) generated an impedance of 139 ohms. For electrode signal testing (and refer to...) Figure 25 The impedance of the SRM complex was 170Ω, and that of the Silver Macrode plus hydrogel was 172Ω. It features OMNI-WAVE. TM The measurement voltage and impedance of the H-502 FLEXCON dry electrode are similar to or better than those of the Silver Mactrode+ (hydrogel) electrode.

[0091] Those skilled in the art will understand that various modifications and variations can be made to the above-disclosed embodiments without departing from the spirit and scope of the invention.

Claims

1. An isotropically conductive composite comprising: a dielectric polymeric material, wherein a polarizable material is substantially dispersed in the dielectric polymeric material, wherein the polarizable material is configured to be polarized and produce a polarization discharge response; and a continuous conductive material substantially covered by the dielectric polymeric material, wherein the continuous conductive material extends substantially throughout the dielectric polymeric material and is configured to react to the polarization discharge response; wherein the isotropically conductive composite is non-aqueous.

2. The isotropically conductive composite of claim 1, wherein, The dielectric polymeric material and the polarizable material do not exhibit significant phase separation even after being exposed to a temperature of 100°F and a relative humidity of 95% for 3 days.

3. The isotropically conductive composite of any one of claims 1-2, wherein, The polarizable material is uniformly dispersed in the dielectric polymeric material.

4. The isotropically conductive composite of any one of claims 1-2, wherein, The dielectric polymeric material is a pressure sensitive adhesive.

5. The isotropically conductive composite of claim 4, wherein, The pressure sensitive adhesive comprises an acrylic copolymer or a copolymer thereof.

6. The isotropically conductive composite of any one of claims 1-2, wherein, The dielectric polymeric material comprises a non-tacky polymer.

7. The isotropically conductive composite of claim 6, wherein, The non-tacky polymer is a thermoplastic polyurethane.

8. The isotropically conductive composite of any one of claims 1-2, wherein, The polarizable material comprises a quaternary ammonium salt.

9. The isotropically conductive composite of any one of claims 1-2, wherein, The continuous conductive material comprises a woven fabric or a nonwoven fabric.

10. The isotropically conductive composite of claim 9, wherein, The woven fabric or the nonwoven fabric comprises carbon fibers.

11. The isotropically conductive composite of any one of claims 1-2, wherein, The continuous conductive material comprises a metal foil.

12. The isotropically conductive composite of claim 11, wherein, The metal foil is an aluminum foil.

13. The isotropically conductive composite of any one of claims 1-2, wherein, The continuous conductive material comprises a wire mesh.

14. The isotropically conductive composite of claim 1, wherein, The polarization discharge response is configured such that when a first portion of the polarizable material is polarized, it is capable of polarizing a first portion of the continuous conductive material.

15. The isotropically conductive composite of claim 14, wherein, When the first portion of the continuous conductive material is polarized, it is capable of polarizing a second portion of the polarizable material.

16. The isotropically conductive composite of claim 1, wherein, The polarizable material is capable of being polarized under the influence of an alternating electric field.

17. The isotropically conductive composite of claim 1, wherein, The composite comprises up to 45 wt% of the polarizable material based on the total weight of the polarizable material and the dielectric material.

18. The isotropically conductive composite of claim 1, wherein, The composite comprises 5 wt% to 45 wt% of the polarizable material based on the total weight of the polarizable material and the dielectric material.

19. The isotropically conductive composite of claim 1, wherein, The isotropically conductive composite adheres to a person's skin.

20. The isotropically conductive composite of claim 19, wherein, The isotropically conductive composite is capable of detecting electrical signals from a person.

21. The isotropically conductive composite of claim 19, wherein, The isotropically conductive composite is capable of transmitting electrical signals to a person's skin.

22. The isotropically conductive composite of claim 1, comprising a first surface and a second surface opposite thereto, wherein, A first release liner is attached to at least a portion of the first surface and a second release liner is attached to at least a portion of the second surface.

23. The isotropically conductive composite of claim 1, comprising a first surface and a second surface opposite thereto, wherein, An electrode connection is attached to at least a portion of the first surface and wherein a lead wire is attached to at least a portion of the electrode connection.

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