Electrode interfaces for neuromodulation device and method for use

Abstract

A neuromodulation device may include a controller configured to generate pulse waveforms. A device may include a first and second electrodes configured to be worn on the skin of a user. The electrodes may include a bar that extends along a distal end of the respective electrode and a set of traces electrically connected to the bar, wherein the first set of traces form a positive impedance gradient from the distal end of the electrode to a proximal end of the electrode with respect to a geometric center between the first and second electrodes.

Description

PATENT Attorney Docket No. 125847.8039.WO01ELECTRODE INTERFACES FOR NEUROMODULATION DEVICE AND METHOD FOR USE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application No. 63 / 605,098, titled “Electrode Interfaces for Neuromodulation Device and Method for Use” and filed on December 1, 2023, which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0002] Various embodiments relate to electrical neuromodulation. More particularly, methods and devices herein provide electrical neuromodulation for treating symptoms of chronic and acute pain as well as other conditions. BACKGROUND

[0003] Pain is the mental manifestation of a neurological response to various physiological and psychological ailments. Pain serves as a warning of physical injury or biological dysfunction. Sometimes pain persists much longer than it takes for the healing of the initial injury to occur, and may be very difficult to alleviate. The most common pain relief methods employ drugs (e.g., opioids) that act to block neurotransmission pathways within the body. Often such drugs are not effective for pain relief over the long term, or produce unacceptable side effects. Consequently, various forms of electrical stimulation such as spinal cord stimulation (SCS) and transcutaneous electrical nerve stimulation (TENS) have also been employed to alleviate pain.

[0004] SCS is effective but is an invasive procedure and has all the typical risks associated with implantable devices, as well as the risk of serious damage to the spinal cord. Conventional TENS devices are not effective in all patients due to the difficulty in picking effective settings and it may produce effects which only last during stimulation and do not produce long term pain relief. Moreover, many patients find conventional TENS at therapeutically effective levels to be uncomfortable. 1 168329311.1PATENT Attorney Docket No. 125847.8039.WO01BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 illustrates a conventional example of a neuromodulation device with a pair of electrode interfaces.

[0006] Figure 2 is a block diagram illustrating modules of a neuromodulation device, according to some embodiments.

[0007] Figure 3 is a block diagram illustrating phases of an electrical pulse output from a neuromodulation device, according to some embodiments.

[0008] Figure 4 is a pulse waveform diagram illustrating phases of one variation of an electrical pulse output by a neuromodulation device as a simplified waveform, according to some embodiments.

[0009] Figure 5 illustrates an electrode interface for a neuromodulation device for applying TENS, according to some embodiments.

[0010] Figure 6 illustrates an exploded view of the neuromodulation device of Figure 5.

[0011] Figure 7 illustrates an example of a trace mesh for an electrode according to some embodiments.

[0012] Figure 8 illustrates another example of a trace mesh for an electrode according to some embodiments.

[0013] Figure 9 illustrates another example of a trace mesh for an electrode according to some embodiments.

[0014] Figure 10 illustrates a neuromodulation device for applying TENS, according to some embodiments.

[0015] Figure 11 illustrates a neuromodulation device for applying TENS, according to some embodiments.

[0016] Figure 12 illustrates a flow diagram for a method of operating a neuromodulation device, according to some embodiments.

[0017] Figure 13 includes an example of a neuromodulation device, designed and produced in accordance with the embodiments described herein, 2 168329311.1PATENT Attorney Docket No. 125847.8039.WO01that has a more uniform gradient of current density across the electrode interfaces.

[0018] Various features of the technology described herein will become more apparent to those skilled in the art from a study of the Detailed Description in conjunction with the drawings. Various embodiments are depicted in the drawings for the purpose of illustration. However, those skilled in the art will recognize that alternative embodiments may be employed without departing from the principles of the technology. Accordingly, although specific embodiments are shown in the drawings, the technology is amenable to various modifications. DETAILED DESCRIPTION

[0019] Many conventional neuromodulation devices for applying transcutaneous electrical nerve stimulation (TENS) offer limited effectiveness in patients for a variety of reasons. One reason is that the physical construction of many neuromodulation devices means that the devices are not effective in offering a user of the device pain relief while also remaining comfortable and not interfering with daily activities. For example, many conventional neuromodulation devices are bulky or difficult to wear. Another reason is that neuromodulation devices typically are configured to apply constant electrical signals to a user, with limited adjustability. Accordingly, many users find conventional neuromodulation devices to be uncomfortable or irritating when signals are applied at a current level proven to be therapeutically effective. While some neuromodulation devices allow a user to reduce the amplitude of the signal, conventional modifications of a neuromodulation signal result in less effectiveness for therapeutic treatment.

[0020] Introduced here are neuromodulation devices – and methods of operating the same – that overcome the deficiencies of conventional neuromodulation devices to provide effective pain relief while avoiding many of the downsides of conventional neuromodulation devices. That is, neuromodulation devices and methods according to exemplary embodiments herein are configured to improve pain relief while avoiding user discomfort. 3 168329311.1PATENT Attorney Docket No. 125847.8039.WO01

[0021] In addition to the above, many conventional neuromodulation devices are not comfortable to users while delivering therapeutically effective signals because of their construction. Specifically, conventional neuromodulation devices employ an electrode arrangement that does not effectively distribute electrical signals across an area of the skin of the user. Instead, current is concentrated in small areas, and users commonly perceive irritation or discomfort in these “hot spots” even though conventional neuromodulation devices use low-voltage current. This current concentration is due to Ohm’s law. Some conventional neuromodulation devices even employ point electrodes that do not effectively distribute current across an area of the skin, further exacerbating this issue. Some conventional neuromodulation devices employ point electrodes that introduce current into a gel pad, which in turn transmits the current to the user’s skin. However, due to the impedance of the user’s body between these point electrodes, the overall impedance is different at different locations of such conventional gel pads, resulting in the current being concentrated even though a gel pad is used to distribute current. An example of current concentration in conventional neuromodulation devices is shown and described further with reference to Figure 1.

[0022] Also introduced here are electrodes for a neuromodulation device that more effectively distribute current across an area on a user’s skin during application of electrical signals to the user compared to conventional neuromodulation devices. For a similarly or identically sized device, the electrode arrangements of exemplary embodiments herein may increase the effective area of the electrode, thereby making the electrode more comfortable. As a result, higher amplitude electrical signals may be applied to a user as a part of a therapeutically effective TENS treatment without causing discomfort. A user may therefore be able to apply higher amplitude and more effective signals without increasing the size of the neuromodulation device compared to conventional neuromodulation devices.

[0023] Some electrodes of exemplary embodiments herein are configured to account for the overall impedance through a user’s body between two electrodes by providing a conductive trace along a distalmost end of the 4 168329311.1PATENT Attorney Docket No. 125847.8039.WO01electrode with respect to a center of the neuromodulation device or a center of a pathway for current through the body. The conductive trace may be equipotential along the distalmost side of the electrode, such that current is introduced to the user’s skin at equal impedance across a width of the electrode, for example, measured in a direction perpendicular to the direction from the electrode to the center of the neuromodulation device or a center of the pathway for current through the body. The distalmost end of the electrode may be a location where the overall impedance through the user’s body is greatest, as the distance of the current travel through the body is greatest. Accordingly, by introducing the current to the user’s skin at the distalmost end of the electrode, the current will flow both through the body and through an area of the electrode proximal to the conductive trace, resulting in more even current distribution across the entire electrode area. A conductive hydrogel pad may also be employed in some embodiments to assist in this distribution of current across the entire electrode area.

[0024] Some electrodes of exemplary embodiments herein are configured to account for the overall impedance through a user’s body between two electrodes by having a positive impedance gradient across the area of the first electrode in the direction of the second electrode. This positive impedance gradient ensures that overall impedance for current traveling through the electrode and the body is approximately the same across the entire area of the first electrode, such that current is not concentrated in an area less than the approximate area of the electrode. Several examples of electrode arrangements implementing a non-uniform electrode impedance for neuromodulation devices are discussed herein with reference to Figures 5-11.

[0025] Given the electrode arrangements discussed herein, a neuromodulation device according to embodiments herein can: Provide enhanced comfort for a user compared to conventional electrode arrangements in neuromodulation devices; Provide enhanced comfort for a user for a same size electrode; Provide greater amplitude electrical signals to a user that may be more therapeutically effective while maintaining user comfort; 5 168329311.1PATENT Attorney Docket No. 125847.8039.WO01Evenly distribute current entering a user’s skin across an entire area of an electrode; and Avoid current concentration or “hot spots” for wearable electrodes.

[0026] Embodiments herein may be described in the context of a “user.” A “user” may be a living body receiving electrical signals from an electrode or transmitting signals to an electrode. In some embodiments, a user may be human. In other embodiments, a user may be an animal. Accordingly, electrodes and neuromodulation devices according to embodiments herein may be used in connection with any living body.

[0027] Embodiments herein may refer to a “bar” forming a part of an electrode. In some embodiments, a “bar” may be a generally straight electrical trace that is configured to conduct current. In some embodiments, “bars” may be electrical traces that generally conduct current at a fixed impedance along the length of the bars. In some embodiments, a “bar” may be approximately equipotential along its length. In some embodiments, one or more bars may define a periphery of an electrode.

[0028] Embodiments herein may refer to relative positions “distal” and “proximal.” According to embodiments herein, “distal” is an outward direction relative to either a geometric center of an electrode pair or a midpoint on an electrical pathway between a first electrode and a second electrode. Accordingly, a “distal end” or a “distal side” of an electrode may be an end or side of the electrode furthest from the geometric center of the electrode pair or the midpoint on an electrical pathway between the electrode and another electrode. According to embodiments herein, “proximal” is an inward direction relative to either a geometric center of an electrode pair or a midpoint on an electrical pathway between a first electrode and a second electrode. Accordingly, a “proximal end” or a “proximal side” of an electrode may be an end or side of the electrode closest to the geometric center of the electrode pair or the midpoint on an electrical pathway between the electrode and another electrode. 6 168329311.1PATENT Attorney Docket No. 125847.8039.WO01

[0029] In some embodiments herein, a neuromodulation device may be a self-contained device. For example, in some embodiments, a neuromodulation device may include a housing that houses a first electrode and a second electrode. In some embodiments, a first electrode and second electrode may have a fixed relationship to one another. In other embodiments, a first electrode and a second electrode may be independent from one another, such that the first electrode and the second electrode are able to be independently positioned on a user’s skin. In some embodiment embodiments, a first electrode and a second electrode may be connected to a controller via respective flexible wires.

[0030] Some embodiments herein are discussed with reference to a flow of current from a first electrode to a second electrode. In other embodiments, current may flow from a second electrode to a first electrode. As a part of TENS treatment, a direction of current flow may be reversed during a treatment session. Accordingly, electrodes described herein may be employed interchangeably as a source electrode or a sink electrode.

[0031] Embodiments may be described in the context of computer- executable instructions for the purpose of illustration. However, aspects of the approach could be implemented via hardware or firmware instead of, or in addition to, software.

[0032] Terminology

[0033] References in the present disclosure to “an embodiment” or “some embodiments” mean that the feature, function, structure, or characteristic being described is included in at least one embodiment. Occurrences of such phrases do not necessarily refer to the same embodiment, nor are they necessarily referring to alternative embodiments that are mutually exclusive of one another.

[0034] Unless the context clearly requires otherwise, the terms “comprise,” “comprising,” and “comprised of” are to be construed in an inclusive sense rather than an exclusive or exhaustive sense. That is, in the sense of “including but not limited to.” The term “based on” is also to be construed in an inclusive sense. Thus, the term “based on” is intended to mean “based at least in part on.” 7 168329311.1PATENT Attorney Docket No. 125847.8039.WO01

[0035] The terms “connected,” “coupled,” and variants thereof are intended to include any connection or coupling between two or more elements, either direct or indirect. The connection or coupling can be physical, logical, or a combination thereof. For example, elements may be electrically or communicatively coupled to one another despite not sharing a physical connection.

[0036] The term “module” may refer broadly to software, firmware, hardware, or combinations thereof. Modules are typically functional components that generate one or more outputs based on one or more inputs. A computer program may include or utilize one or more modules. For example, a computer program may utilize multiple modules that are responsible for completing different tasks, or a computer program may utilize a single module that is responsible for completing all tasks.

[0037] When used in reference to a list of multiple items, the word “or” is intended to cover all of the following interpretations: any of the items in the list, all of the items in the list, and any combination of items in the list. Overview of Conventional Neuromodulation Device

[0038] Figure 1 illustrates a conventional example of a neuromodulation device 100 with a pair of electrode interfaces. The neuromodulation device 100 is configured to apply an electrical signal to a user of the neuromodulation device to inhibit transmission of pain signals through the nervous system to the brain. The neuromodulation device 100 is configured as a patch 102 configured to be worn on the skin of a user. The patch 102 may include an adhesive material allowing the neuromodulation device 100 to adhere to the skin. The neuromodulation device 100 includes a controller 104 configured to control generation of the electrical signal. The controller 104 may be powered by an onboard power source, such as a battery.

[0039] As shown in Figure 1, the neuromodulation device 100 includes a first electrode 106 disposed in a first gel pad 108. Electrical current is configured to flow through the first electrode 106, through the gel pad 108, and into the skin of the user of the neuromodulation device 100. The neuromodulation 8 168329311.1PATENT Attorney Docket No. 125847.8039.WO01device 100 also includes a second electrode 110 disposed in a second gel pad 112. Current is configured to flow from the first electrode 106, into a user’s skin, and to the second electrode 110. The passage of this electrical current is configured to disrupt pain signals in the neurological system of the user, thereby alleviating pain. The first gel pad 108 and the second gel pad 112 are configured to distribute the current over a wider area than the point input / output provided by the first electrode 106 and the point input / output provided by the second electrode 110.

[0040] Many conventional TENS devices include an electrode arrangement like that shown in Figure 1. That is, the neuromodulation device 100 includes conductive gel pads 108, 112 configured to contact the skin of a user and distribute current over a larger area, which may avoid user discomfort. For example, if the electrical current enters the user’s skin at a single point, the electrical current may be more irritating to the user. Accordingly, the gel pads 108, 112 are intended to more evenly distribute the current across a larger area of the skin. Conventional gel pads like those in Figure 1 have an equal impedance across their area. However, as the current flows from the first electrode 106 to the second electrode 110, the impedance of the user’s body changes the overall impedance at different locations on the gel pads 108, 112. A gradient 114 is shown in Figure 1 to illustrate these changes in overall impedance. As shown in Figure 1, the impedance is lower where the first gel pad 108 is closest to the second gel pad 112, as well as where the first electrode 106 is closest to the second electrode 110. Correspondingly, the impedance where the first gel pad 108 is furthest from the second gel pad 112 and the second electrode 110 is higher. The highest impedance is at the outmost corners of the first gel pad 108 with respect to the center of the neuromodulation device 100. Higher impedance is indicated by darker shading. The impedance pattern shown in Figure 1 is similar for the second gel pad 112. As a result of the impedance gradient, the majority of the current is passed through an area smaller than that of the area of the gel pad. The effective current density caused by the impedance gradient of the neuromodulation device 100 may cause user discomfort compared to a lesser current density. 9 168329311.1PATENT Attorney Docket No. 125847.8039.WO01

[0041] As discussed further below, physical arrangements and / or methods described with reference to embodiments herein may address the user discomfort caused by the impedance imbalance shown in Figure 1. Moreover, physical arrangements and / or methods described herein may improve user comfort as well as therapeutic effectiveness of a neuromodulation device without substantially increasing the physical dimension of the neuromodulation device, improving wearability and further increasing user comfort. Overview of Neuromodulation Device and Method of Operation

[0042] Figure 2 is a block diagram illustrating modules of a neuromodulation device 200, according to some embodiments. The control electronics module 202 generally comprises a microcontroller which may be programmable to provide the desired pulse signals to the patient. The control electronics module 202 may also include the various electronics that are used to effect the treatment and control the output on / off state, pulse amplitude, timing, modulation, and other pulse parameters. Examples of such electronics include timers, clocks, DACs, processing units, and the like. In order to actuate and / or interface with the control electronics module 202, a controls module 204 may be in communication with the control electronics module 202 through any number of interface mechanisms, such as buttons, knobs, sliders, capacitive touch sensors, and the like, through which a user can turn the device on / off, adjust amplitude or other settings, etc. Additionally, the controls module 204 or other controller may communicate locally or remotely with the control electronics module 202 through a communication interface module 208 which may include any number of various wired communication mechanisms and / or wireless communication mechanisms. Examples of wireless communication mechanisms (also called “wireless communication protocols”) include Bluetooth®, Bluetooth® Low Energy or Bluetooth® Smart (Bluetooth SIG, Inc., Kirkland, Wash.), ANT, ZigBee, Wi-Fi, near field communication (NFC), infrared (e.g., Infrared Data Association (IrDA) associated wireless communications), etc.

[0043] The control electronics module 202 may provide any number of details, feedback, or information about its operation through an indicator 10 168329311.1PATENT Attorney Docket No. 125847.8039.WO01module 206 which may include any variety of indicators or displays that may be positioned directly upon the neuromodulation device or separately in communication with the control electronics module 202. Generally, the term “indicator” is used to refer to one or more illuminants that visually provide information (e.g., regarding power status, connectivity status, program, etc.) through illumination. Meanwhile, the term “display” is generally used to refer to a panel of illuminants that are collectively controlled to visually present information. Displays may comprise liquid crystal display (LCD) elements, light- emitting diodes (LEDs), organic LEDs (OLEDs), quantum dots (QDs), electrophoretic elements, and the like.

[0044] In order for the neuromodulation device to provide the electrical stimulation to the patient's body, the control electronics module 202 may be in communication with a pulse generating electronics module 210 which is in communication with electrodes 214 through connecting elements 212. The control electronics module 202 and pulse generating electronics module 210 may be in communication with a power supply module 216 which supplies the power for the electrical stimulation. The power supply module 216 may include a battery such as a lithium-ion battery with associated circuits such as voltage regulators, LDOs, boost or buck converters, etc. The device output may utilize a voltage which is much higher than that available from the battery, and therefore the power supply may optionally include a generating mechanism for providing the high voltage as well as regulated low voltages for the other internal circuits.

[0045] The pulse generating electronics module 210 may include various components, including, but not limited to, amplifiers, op-amps, output filtering or pulse shaping circuits, output limiting or sensing and feedback circuits, elements which provide galvanic isolation, DC blocking, etc., which are configured to produce the electric pulses with controlled shape and amplitude as described herein.

[0046] Each of the various components may be in electrical communication through the connecting elements 212. The connecting elements used may comprise any number of electrically conductive elements, such as connectors, 11 168329311.1PATENT Attorney Docket No. 125847.8039.WO01printed conductive traces, flex circuit boards, and the like, which provide electrical connection from the electronics to the electrodes or between any number of electrical components.

[0047] The electrodes 214 electrically coupled to the pulse generating electronics module 210 may be shaped in various configurations for facilitating placement upon the patient depending upon the region of the body to be treated. Accordingly, the electrodes may be external for providing an electrical connection from the device output to the body through the skin, particularly to the target tissues or nerves.

[0048] External electrodes, in one variation, may be constructed of a conductive current-distributing element, an electrode interface (such as a silver chloride coated silver, stainless steel, graphite, etc.) and a hydrogel (such as polyacrylamide or other stable and biocompatible gel with good adhesion) which contains a conductive solution (typically sodium chloride). The electrodes may be a driven as a pair of electrodes where the current flows from a first electrode to a second electrode, or as a more complex multi-polar setup, for example, in a quadrupolar setup, with four electrodes driven as any one of six alternating pairs. Exemplary electrode configurations will be discussed further with reference to Figure 5.

[0049] In other variations, the neuromodulation device may additionally and / or optionally include additional features or elements. For example, in one variation, the device may be controlled entirely via a communication interface using, for example, wireless communication from a controller located remotely from the neuromodulation device. Such remotely located controllers may include, for example, smartphones or other programmable devices, which may communicate via any number of wireless communication protocols (e.g., Bluetooth® Low Energy). Such a variation may remove the need for any controls or indicators on the device itself as the controls module 204 may be located remotely. In yet another alternative, the device may directly incorporate the controls module 204 upon the neuromodulation device itself so that it may be controlled entirely through an interface located upon the device. 12 168329311.1PATENT Attorney Docket No. 125847.8039.WO01

[0050] Additionally, and / or alternatively, the control electronics module 202 and power supply module 216 may be packaged as a compact device that may be removably attached as a unit upon electrodes 214. For example, the electrodes 214 may be embedded, suspended, or otherwise situated in polyacrylamide hydrogel with silver ink conductive traces printed on a polymer film base. The electrodes 214 may be placed upon the region of interest upon the patient body and the device may be temporarily coupled to an engagement mechanism which also allows for the electrical communication between the pulse generating electronics module 210 and the electrodes 214 to effect treatment upon the patient. This variation as well as others described may be combined in any number of combinations as practicable.

[0051] Figure 3 is a block diagram illustrating phases of an electrical pulse output from a neuromodulation device, according to some embodiments. Specifically, Figure 3 shows a block diagram of a representative pulse waveform 300 illustrating the major phases of an electrical pulse output. Using the neuromodulation device 200 of Figure 2, the control electronics module 202 may be programmed to effect a specified pulse waveform generated by the pulse generating electronics module 210 and transmitted through the electrodes 214 and to the area of the patient's body upon which the electrodes 214 are positioned for treatment. Generally, the pulse waveform 300 may have a primary phase 306 followed by an optional dead time 308 period and then a secondary phase 310. Initiating the primary phase 306 is a leading edge 302 having a relatively fast rise time which leads to a spike 304 having an intensity greater than an average intensity of the primary phase 306. The remainder of the primary phase 306 may have an intensity which is lower than the intensity of the spike 304. In some embodiments, the remainder of the primary phase 306 may have an intensity approximately half intensity of the spike 304.

[0052] The dead time 308 period, if included, may have an output amplitude of zero. If the dead time 308 period is omitted, the secondary phase 310 may follow immediately after the primary phase 306 where the secondary phase 310 may have a polarity opposite to that of the primary phase 306. Like the dead time 308 period, the secondary phase 310 may be optionally omitted entirely 13 168329311.1PATENT Attorney Docket No. 125847.8039.WO01from the pulse waveform 300. The treatment pulses having the pulse waveform 300 may be repeated during a treatment where a specified time interval period 312 may be present between each individual pulse waveform 300.

[0053] While the output is described here in terms of amplitude, this may include a measure of either current or voltage. In one embodiment, the pulse waveforms 300 may be produced by a circuit which is a voltage-limited current source, and the amplitudes may comprise current amplitudes. Using a current control allows for the effective movement of charges to be less dependent on the electrode impedance (which may change with skin condition or over time) and less dependent on the tissue impedance (which may change with placement or individually).

[0054] In another embodiment, the output may also comprise a voltage source or current-limited voltage source, since in the short term the tissue and electrode impedances are relatively constant and so the current is approximately equal to the voltage times a constant factor. In this case, the output may require more frequent adjustments. However, controlled or produced, the amplitude pattern shown describes the variation in electrical field strength independent of the effects of variation in electrode impedance or the specifics of the control circuit.

[0055] If any parameters (such as timings or amplitude) of the output electrical pulses depend on the load impedance, they may be measured using a resistive-capacitive test load simulating the electrodes and human body.

[0056] Figure 4 graphically illustrates an individual representative pulse waveform 300 described in Figure 3 with each of the major phases of an electrical pulse output. The primary phase 306 is shown including the leading edge 302 of spike 304 over a relatively short rise time and the remainder of the primary phase 306 where the intensity of the spike 304 is significantly greater than an average intensity of the primary phase 306 and where the intensity of the remainder is significantly lower than the intensity of the spike 304, for example, about half the intensity. This may then be followed by the secondary 14 168329311.1PATENT Attorney Docket No. 125847.8039.WO01phase 310 which may have its polarity opposite to that of the primary phase 306, as shown.

[0057] The transition or edge rise and fall times are measured as the time from, for example, 10% to 90% of the change from initial to final level. Widths are measured as the time from, for example, the 10% level on the rising edge to the 10% level on the falling edge. The illustration of the pulse waveform 300 is intended to be illustrative of the relative shape of the waveform with its timing measurements. Hence, the amplitudes during the spike 304, primary phase 306 and secondary phase 310 of the pulse waveform 300 do not need to be held constant as shown in Figure 4. Any pulse shape such that the spike 304 has a relatively fast rise time and high peak amplitude 410, and the typical amplitude during the remainder of the primary phase 306 after the spike 304 is significantly less than the spike 304, may provide an effective pulse waveform 300. For example, if it is easier for the pulse generating or control electronics to produce, the primary phase 306 and secondary phase 310 may be comprised of, for example, piecewise segments of exponentially decaying waveforms (e.g., due to capacitor discharge or inductor decay), piecewise linear, trapezoidal, or any other shape. The spike 304 itself may be shaped as, for example, a half-sine wave, sine, parabolic, or similar waveform, as it is not necessary for it to have a constant level (e.g., “flat top”).

[0058] Additionally, the transitions between the spike 304, primary phase 306, optional dead time, secondary phase 310, and interval period 312 do not need to have rapid rise and fall times, or in any case the rapid rise and fall times are not necessary for effectiveness. However, it may be desirable to have a relatively rapid and / or fall time 404 at the end of the spike 304 to increase patient comfort. Once the brief time at maximum amplitude 402 during the spike 304 has passed, it is unlikely that any high but sub-maximum amplitude would have a physiological effect; however, it may cause greater charging of the skin capacitance and thus skin discomfort and for that reason it is desirable for the spike 304 to transition to the lower level during the remainder of the primary phase 306 relatively quickly. The fall time 406 at the end of the primary phase 306 and the fall time 408 from secondary phase 310 to the interval period 312 15 168329311.1PATENT Attorney Docket No. 125847.8039.WO01state or inter-pulse interval may be implemented in different ways while still having a therapeutically effective pulse shape as described herein. For example, as shown in Figure 4, the fall time 406 may be stepwise, and the fall time 408 may be exponential decay. Other arrangements may be implemented, in other embodiments. The pulse may have an overall time period 412.

[0059] Turning now to the individual portions of the pulse waveform 300, the spike 304 is comprised of a relatively high amplitude 410, short duration spike which has a leading edge 302 with a fast rise time. The effective electric field during the spike 304 is expected (for several reasons described in more detail below) to be high enough to be able to drive conformational changes of the cellular components which are targeted therapeutically directly, by the electrostatic forces acting on fixed charges or dipoles therein. A relatively high electric field strength is desirable in order to produce conformational changes and thereby modulate the physiological function of the target cellular components or molecules; hence, an initial spike 304 with an amplitude 402 which is significantly higher than the average amplitude during the primary phase 306.

[0060] The transition between spike 304 and primary phase 306 may not be as fast as the leading edge 302 of the spike 304. In one embodiment, the transition is a rapid linear transition with a controlled fall time equal to the rise time of the leading edge 302 of the spike 304, but this is not required. Many variations in the transition between the spike 304 and primary phase 306 are possible which accomplish the same goal of relatively rapid transition using different profiles.

[0061] While an exemplary pulse waveform is shown and described with reference to Figure 4, electrodes for neuromodulation devices described herein are not limited to a particular shape or type of waveform, nor are electrodes limited to any specific parameter of a waveform. For example, electrodes described herein may be used in connection with waveforms including square waves, triangular waves, sawtooth waves, sine waves, non-periodic waveforms, and / or other complex waves. 16 168329311.1PATENT Attorney Docket No. 125847.8039.WO01

[0062] Figure 5 illustrates an electrode interface for a neuromodulation device 500 for applying TENS, according to some embodiments. The neuromodulation device 500 is configured to apply an electrical signal to a user of the neuromodulation device to inhibit transmission of pain signals through the nervous system to the brain. The neuromodulation device 500 is configured as a patch 502 configured to be worn on the skin of a user. The patch 502 may include an adhesive material allowing the device 500 to adhere to the skin. In some embodiments, the patch 502 may include one or more gel pads configured to adhere to the skin. The neuromodulation device 500 includes a controller 503 configured to control generation of the electrical signal. The controller 503 may be powered by an onboard power source, such as a battery. In other embodiments, the controller 503 may be powered by an external power source. In some embodiments, the controller 503 may be proximate to the geometric center of the neuromodulation device 500.

[0063] The neuromodulation device 500 differs from the conventional neuromodulation device 100 of Figure 1 in the arrangement of its electrodes and, optionally, the process of applying the electrical signals to the user. Specifically, the electrode arrangement shown in the example of Figure 5 provides a more even distribution of current into a user’s skin by providing an electrode arrangement that adjusts for the impedance gradient found in conventional neuromodulation devices. Notably, as discussed further below, the electrode arrangement of Figure 5 eliminates point electrodes to better distribute current over the area of the neuromodulation device. As a result, more current may be applied to a user as a part of a treatment to provide more effective pain relief while maintaining the comfort of the user by avoiding concentration of current in small areas.

[0064] As shown in Figure 5, the neuromodulation device 500 includes a first controller input / output 504 and a second controller input / output 506 for providing electrical connections to a first electrode 505 and a second electrode 507, respectively. The first electrode 505 includes perimeter bars 508 that conduct the current from the first controller input / output 504. Specifically, the perimeter bars 508 are connected to the first controller input / output 504 via 17 168329311.1PATENT Attorney Docket No. 125847.8039.WO01traces 510 and convey the current to a distal bar 509 located at a distal end of the first electrode 505 with respect to a geometric center between the first electrode 505 and the second electrode 507. In the example of Figure 5, this geometric center the same as the geometric center of the neuromodulation device 500. The distal bar 509 distributes the current along a line perpendicular to the treatment current direction (horizontally on the page as depicted in Figure 5). Notably, the distal bar 509 provides an input point for the highest voltage at locations that are a furthest travel path for the current to the second controller input / output 506. In some embodiments as shown in Figure 5, the perimeter bars are connected to opposite ends of the distal bar 509. In some embodiments, the perimeter bars 508 and the distal bar 509 are positioned in C-shape. Such an arrangement may reduce voltage potential differences along the distal bar 509 compared to a distal bar connected at one end only. In other embodiments a distal bar 509 may be connected to a first controller input / output 504 at one end with appropriately low impedance such that the voltage potential differences along a length of the distal bar are negligible.

[0065] The first electrode 505 further includes a set of conductive traces 512A, 512B (e.g., at least three traces) that are connected to the distal bar 509 at trace connections 511. The conductive traces 512A, 512B are interconnected to form a trace mesh and provide an equipotential path for current in a direction parallel to the distal bar 509. In the example of Figure 5, the conductive traces 512A, 512B are not directly connected to the perimeter bars 508 and are instead connected to the perimeter bars 508 only through the distal bar 509. In other embodiments conductive traces may be connected to parallel perimeter bars directly. In some such embodiments, an impedance barrier may be disposed between the traces and the perimeter bars, such that the lowest electrical impedance remains at a distal end of the first electrode 505 at the distal bar 509.

[0066] As shown in Figure 5, moving from the furthest travel distance to the shortest travel distance (e.g., to the second electrode 507), the conductive traces 512A, 512B decrease in thickness to increase impedance to offset the decrease in impedance caused by the shorter travel path through the user’s 18 168329311.1PATENT Attorney Docket No. 125847.8039.WO01body. In the example of Figure 5, the conductive traces 512A, 512B decrease in thickness from bottom to top of the page. A first electrode trace 512A closer to the distalmost edge of the neuromodulation device 500 has a greater thickness and therefore less impedance than a second electrode trace 512B closer to the geometric center. The thicknesses of the conductive traces 512A, 512B may decrease according to a gradient based on the size of the neuromodulation device, such that the overall impedance for current through the first electrode and through the user’s body for the entire electrode area is approximately equal. In some embodiments as shown in Figure 5, the conductive traces 512A, 512B include curved portions (e.g., semi-circular or otherwise circular portions) which may eliminate sharp edges in the direction of current flow that would otherwise cause “hot spots” in concentration of electric fields applied to the body at regions where conductors meet at an acute angle. Overall, the electrode arrangement shown in Figure 5 is configured to even out current density across the entire area of the first electrode 505. As a result, the electrode may be more comfortable for a given size of neuromodulation device 500 and the same amount of current compared to conventional neuromodulation devices like that shown in Figure 1.

[0067] The second electrode 507 has a mirrored arrangement to that of the first electrode 505. In the depicted embodiment, the second electrode 507 is symmetrical to the first electrode 505 and is mirrored across a center axis passing through the first controller input / output 504 and the second controller input / output 506 (horizontal on the page as depicted in Figure 5). The second electrode 507 includes perimeter bars 514 that conduct the current to the second controller input / output 506 via traces 516. The second electrode 507 includes a distal bar 515 positioned at a distal end of the second electrode. The distal bar 515, like distal bar 509, provides an equipotential input for the current which is distributed along a line perpendicular to the treatment current direction (horizontally on the page as shown in Figure 5). The distal bar 509 is connected to the perimeter bars 514 at opposing ends of the distal bar 509. The second electrode 507 further includes a set of conductive traces 518A, 518B that are connected to the distal bar 515 at trace connections 517. Moving from the 19 168329311.1PATENT Attorney Docket No. 125847.8039.WO01furthest electrical travel distance through the body to the shortest travel distance through the body (e.g., from the first electrode 505 to the second electrode 507), the conductive traces 518A, 518B decrease in thickness to increase impedance to offset the decrease in impedance caused by the shorter travel path through the user’s body. In the example of Figure 5, the conductive traces 518A, 518B decrease in thickness from top to bottom of the page. A first electrode trace 518A closer to the distalmost edge of the neuromodulation device 500 has a greater thickness and therefore less impedance than a second electrode trace 518B closer to the geometric center. This gradient provides a more even current distribution through the second electrode 507, thereby improving comfort of the neuromodulation device 500 for a particular current. Similar to the first electrode 505, the traces 518A, 518B of the second electrode 507 provide an equipotential input for current across a width of the second electrode 507 (e.g., in a direction horizontal on the page as depicted in Figure 5).

[0068] According to some embodiments as shown in Figure 5, the conductive traces 512A, 512B and conductive traces 518A, 518B form a part of respective larger trace meshes. A trace mesh includes a plurality of conductive traces interconnected to form a mesh covering an area. This mesh distributes current across the area of the respective electrode. In some embodiments, each electrode trace 512A, 512B, 518A, 518B has an equal impedance across a width of the respective electrode (horizontal on the page as depicted in Figure 5). Along the positive gradient direction toward a geometric center between the first electrode 505 and the second electrode 507, the conductive traces in a trace mesh increase in impedance. In the example of Figure 5, the traces sequentially decrease in diameter, thereby increasing the impedance of the sequential traces. In other examples, a trace mesh may implement material changes in sequential traces or other arrangements to increase the impedance of sequential conductive traces. In some embodiments, a trace may have an impedance gradient based on an alteration of the material resistance via doping. In the example of Figure 5, a trace mesh includes twelve conductive traces. In other embodiments other numbers of 20 168329311.1PATENT Attorney Docket No. 125847.8039.WO01traces may be implemented. Other examples of a trace mesh are discussed further with reference to Figures 7-9.

[0069] As noted above, in some embodiments, conductive traces 512A, 512B, 518A, 518B may include curved portions which may eliminate sharp edges in the direction of current flow that would otherwise cause electric field concentration or “hot spots” in areas where conductors meet at an acute angle. In the example of Figure 5, the curved portions are semi-circular portions. As shown in Figure 5, each electrode trace includes a series of connected semi- circles in a row extending parallel to the distal bars 509, 515 of the electrodes, for example, in a width direction. The semi-circles in adjacent conductive traces are offset in the width direction, such that each semi-circle overlaps with two adjacent semi-circles in either a proximal or distal direction. In this manner, the trace meshes of Figure 5 are arranged in a scale pattern. Other arrangements of a trace mesh and curved portions are discussed further below with reference to Figures 7-9.

[0070] In some embodiments, the first electrode 505 and the second electrode 507 may include gel pads configured to contact the skin of the user and further distribute current over the entire area of the respective electrode. The electrode arrangements discussed above may supplement the gel pads to increase the effective area of the gel pads by distributing current across the entire area of the gel pad according to overall impedance between the first controller input / output 504 and the second controller input / output 506. In some embodiments, a neuromodulation device may include two gel pads, with one gel pad for each electrode. In other embodiments, a single gel pad may be employed for a neuromodulation device, where each electrode is disposed on separate portions of the same gel pad.

[0071] In the example of Figure 5, the neuromodulation device 500 is self- contained. That is, the first electrode 505 and the second electrode 507 form portions of the same patch 502. Accordingly, the relative spacing and positions of the first electrode 505 is fixed relative to the second electrode 507. In other embodiments, the first electrode 505 and the second electrode 507 may be separate from one another, for example, as separate patches. In some such 21 168329311.1PATENT Attorney Docket No. 125847.8039.WO01embodiments, the first electrode 505 and the second electrode 507 may be independently positioned relative to one another. In some such embodiments, the electrodes may be oriented such that their impedance gradients point toward one another along an electrical pathway. In this manner, the impedance of each electrode will be least at the longest distance along the electrical pathway, and the impedance will be most as the shortest distance along the electrical pathway.

[0072] Figure 6 illustrates an exploded view of the neuromodulation device 500 of Figure 5. As shown in Figure 5, the neuromodulation device includes a controller 503 that is attached to an upper housing 520. The controller 503 is configured to control delivery of electrical signals to the first electrode 505 and the second electrode 507. In some embodiments, the controller 503 may include a power source, such as a battery. As shown in Figure 6, the first controller input / output 504 is connected to the controller 503 with a fastener 524, for example, a rivet, eyelet, or screw. Similarly, the second controller input / output 506 is connected to the controller 503 with a fastener 524. In the example of Figure 5, the fasteners 524 are configured to pass through holes 522 formed in the upper housing 520. The fasteners 524 may be conductive and may form electrical connections between the controller input / outputs and the controller 503. In other embodiments, another electrical connection may be made between the controller and the first electrode and second electrode, and the present disclosure is not limited in this respect. In some embodiments, the upper housing is formed of a dielectric material. The traces 512 and distal bar 509 of the first electrode 505 are received in a first pocket 528A in a lower housing 526. Similarly, the traces 518 and the distal bar 515 of the second electrode 507 are received in a second pocket 528B of the lower housing 526. In some embodiments, the lower housing 526 is formed of a dielectric material.

[0073] In some embodiments as shown in Figure 6, the neuromodulation device 500 includes a first gel pad 530A configured to be electrical communication with the first electrode 505. The neuromodulation device 500 also includes a second gel pad 530B configured to be in electrical communication with the second electrode 507. The first and second gel pads 22 168329311.1PATENT Attorney Docket No. 125847.8039.WO01are configured to assist in distributing current across an entire area of the electrode and the current is transmitted to the user. In some embodiments, the neuromodulation device includes an optional adhesive layer 532 configured to enhance adherence of the gel pads to a user’s skin.

[0074] Figure 7 illustrates an example of a trace mesh 700 for an electrode according to some embodiments. The trace mesh 700 may form a part of an electrode and may be connected to a controller via a distal bar similar to the arrangement discussed with reference to Figure 5. As shown in Figure 7, the trace mesh 700 includes a plurality of conductive traces that are interconnected to form the mesh. The trace mesh 700 has a positive impedance gradient moving down on the page, which may correspond to a proximal direction.

[0075] Each of the conductive traces in the trace mesh of Figure 7 includes curved portions. In the example of Figure 7, a distalmost trace includes distalmost trace connectors 706 that may connect to a distal bar. The distalmost trace also includes a semi-ellipse 702 that crosses over a first quarter-ellipse 704A and a second quarter ellipse 704B. The first quarter-ellipse and second quarter-ellipse are mirrored across a center axis and intersect with the semi- ellipse 702. The resulting shape is that of two columns of X’s in the trace mesh 700, with each trace forming a row having two X’s. Each sequential row in the trace mesh 700 has a greater impedance as a result of a reduced trace diameter moving in the proximal direction (e.g., down on the page as depicted in Figure 7). A proximal-most conductive trace also includes trace connectors 712 connecting to the conductive trace distal to the proximal-most conductive trace. The proximal-most conductive trace also includes a semi-ellipse 708 and two quarter-ellipses 710A, 710B that overlap to form two X’s in two columns. The pattern of the proximal-most conductive trace is like that of the distalmost conductive trace, with the difference being the diameter of the traces. The diameter of the proximal-most trace is less than the diameter of the distalmost trace, meaning the proximal-most trace has a greater impedance than the distalmost trace.

[0076] Figure 8 illustrates another example of a trace mesh 800 for an electrode according to some embodiments. The trace mesh 800 may form a 23 168329311.1PATENT Attorney Docket No. 125847.8039.WO01part of an electrode and may be connected to a controller via a distal bar similar to the arrangement discussed with reference to Figure 5. As shown in Figure 8, the trace mesh 800 includes a plurality of conductive traces that are interconnected to form the mesh. The trace mesh 800 has a positive impedance gradient moving down relative to the page, which may correspond to a proximal direction.

[0077] In the example of Figure 8, the trace mesh 800 is formed by a plurality of circles. The trace mesh includes circles 806A, 806B arranged in a plurality of rows 802 and a plurality of columns 804. Each conductive trace corresponds to a single row 802 in the example of Figure 8. Accordingly, the circles in each row 802 have a common impedance. Moving down each column 804 in a proximal direction, the impedance of each circle is greater than the preceding distal circle. In the example of Figure 8, the diameter of the trace forming the circles is reduced moving proximally down each column 804. Accordingly, a distalmost trace, represented by a first circle 806A, has a diameter greater than a proximal-most trace, represented by a second circle 806B.

[0078] Figure 9 illustrates another example of a trace mesh for an electrode according to some embodiments. The trace mesh 900 may form a part of an electrode and may be connected to a controller via a distal bar similar to the arrangement discussed with reference to Figure 5. As shown in Figure 9, the trace mesh 900 includes a plurality of conductive traces that are interconnected to form the mesh. The trace mesh 900 has a positive impedance gradient moving down relative to the page, which may correspond to a proximal direction.

[0079] In the example of Figure 9, the trace mesh 900 is formed by a plurality of traces arranged in repeating plus shapes arranged in a plurality of rows 902. Each conductive trace corresponds to a row 902. As shown in Figure 9, a distalmost conductive trace includes a plurality of plus-shaped traces 904A arranged in a row 902. Each of the plus-shaped traces 904A overlaps adjacent plus-shaped traces in an overlap region 906A. Each of the plus-shaped traces 904A has a consistent diameter and impedance across the width of the row. Moving proximally, each sequential row repeats the pattern but with a greater 24 168329311.1PATENT Attorney Docket No. 125847.8039.WO01impedance. In the trace mesh of Figure 9, the diameters of the conductive traces are less in each sequential proximal row. In a proximal-most conductive trace, the plus-shaped traces 904B and overlap regions 906B have a trace diameter less than plus-shaped traces 904A and overlap regions 906A of the distalmost conductive trace.

[0080] According to embodiments described herein, a controller may be configured to output a single signal to an electrode. In some cases, impedance gradients (e.g., provided by a trace mesh as described herein) may allow for effective current distribution of the signal over the area of the electrode. In some other embodiments, a controller may be configured to output multiple signals. The multiple signals may be output to different independent traces arrayed along an electrode in a direction parallel to an impedance gradient through a living body. The multiple signals may be controlled to introduce equal amounts of current across the area of the electrode through the independent traces based on the overall impedance through a living body. For example, a voltage of a signal may be increased to introduce the same amount of current at an independent electrode at a location where there is a higher impedance through the body (e.g., further from a geometric center of an electrode pair), compared to an independent electrode at a location where there is a lower impedance through the body (e.g., closer to a geometric center of an electrode pair).

[0081] Figure 10 and Figure 11 illustrate neuromodulation devices for applying TENS, according to some embodiments. Figures 10 and 11 illustrate neuromodulation devices that may employ different trace mesh densities. As shown in Figure 10, the neuromodulation device 1000 includes a first trace mesh 1002 connected to a first distal bar 1004 and a second trace mesh 1006 connected to a second distal bar 1008. Likewise, in Figure 11, the neuromodulation device 1100 includes a second trace mesh 1102 connected to a first distal bar 1104 and a second trace mesh 1106 connected to a second distal bar 1108. The first and second trace meshes of the neuromodulation device 1000 of Figure 10 have a first density, and the first and second trace meshes of the neuromodulation device 1100 of Figure 11 have a second density different than the first density. The trace density of the neuromodulation 25 168329311.1PATENT Attorney Docket No. 125847.8039.WO01device 1000 may be approximately 45% of the area of the electrode, meaning 45% of the area is occupied by the conductive traces. The trace density of the neuromodulation device 1100 may be approximately 60% of the area of the electrode. Differing trace densities may be appropriate depending on the portion of the body. For example, comfort of a neuromodulation device may be improved by increasing density of the trace mesh on more sensitive body portions such as the wrist or hands. In such circumstances, trace densities of more than 45% may be more effective than electrodes with lesser densities.

[0082] Figure 12 illustrates a flow diagram for a method 1200 of operating a neuromodulation device, according to some embodiments. In act 1202, the method includes positioning a first electrode on the skin of a user at a first location. The first electrode may include a positive impedance gradient across an area of the first electrode extending in a first direction toward a second electrode such that an impedance of the first electrode closer to the second electrode is greater than an impedance of the first electrode further from the second electrode. The first direction toward the second electrode may be defined by an electrical travel path through a user’s body. In act 1204, method includes positioning a second electrode on the skin of a user at a second location. The second electrode may include a positive impedance gradient across an area of the second electrode extending in a second direction toward the first electrode such that an impedance of the second electrode closer to the first electrode is greater than an impedance of the second electrode further from the first electrode. Like the first direction, the second direction may be defined by an electrical travel path through a user’s body. The second direction may be an opposite direction along the electrical travel path compared to the first direction. In act 1206, the method includes passing current into the first electrode, through a body of the user, and into the second electrode. The current may flow from a first peripheral edge of the first electrode (e.g., a distal end) toward a second peripheral edge (e.g., a proximal end) of the first electrode opposite the first peripheral edge in the first direction.

[0083] Figure 13 includes an example of a neuromodulation device, designed and produced in accordance with the embodiments described herein, 26 168329311.1PATENT Attorney Docket No. 125847.8039.WO01that has a more uniform gradient of current density across the electrode interfaces. Remarks

[0084] The foregoing description of various embodiments of the claimed subject matter has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed. Many modifications and variations will be apparent to one skilled in the art. Embodiments were chosen and described in order to best describe the principles of the invention and its practical applications, thereby enabling those skilled in the relevant art to understand the claimed subject matter, the various embodiments, and the various modifications that are suited to the particular uses contemplated.

[0085] Although the Detailed Description describes certain embodiments and the best mode contemplated, the technology can be practiced in many ways no matter how detailed the Detailed Description appears. Embodiments can vary considerably in their implementation details, while still being encompassed by the specification. Particular terminology used when describing certain features or aspects of various embodiments should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific embodiments disclosed in the specification, unless those terms are explicitly defined herein. Accordingly, the actual scope of the technology encompasses not only the disclosed embodiments, but also all equivalent ways of practicing or implementing the embodiments.

[0086] The language used in the specification has been principally selected for readability and instructional purposes. It may not have been selected to delineate or circumscribe the subject matter. It is therefore intended that the scope of the technology be limited not by this Detailed Description, but rather by any claims that issue on an application based hereon. Accordingly, the 27 168329311.1PATENT Attorney Docket No. 125847.8039.WO01disclosure of various embodiments is intended to be illustrative, but not limiting, of the scope of the technology as set forth in the following claims. 28 168329311.1

Claims

PATENT Attorney Docket No. 125847.8039.WO01CLAIMS What is claimed is:

1. A neuromodulation device comprising: a controller configured to generate pulse waveforms; a first electrode electrically connected to the controller and configured to be worn on the skin of a user, wherein the first electrode comprises: a first pad that is comprised of a conductive gel and configured to contact the skin of the user, a first bar that extends along a distal end of the first pad, and a first set of traces electrically connected to the first bar; and a second electrode electrically connected to the controller and configured to be worn on the skin of the user, wherein the second electrode comprises: a second pad that is comprised of the conductive gel and configured to contact the skin of the user, a second bar that extends along a distal end of the second pad, and a second set of traces electrically connected to the second bar, wherein: the first set of traces form a positive impedance gradient from the distal end of the first pad to a proximal end of the first pad with respect to a geometric center between the first electrode and the second electrode, and the second set of traces form a positive impedance gradient from the distal end of the second pad to a proximal end of the second pad with respect to the geometric center.

2. The neuromodulation device of claim 1, wherein the positive impedance gradient of the first set of traces extends in a first direction, and wherein the positive impedance gradient of the second set of traces extends in a second direction opposite the first direction. 29 168329311.1PATENT Attorney Docket No. 125847.8039.WO013. The neuromodulation device of claim 1, wherein the first electrode is on a first side of the geometric center, and wherein the second electrode is on a second side of the geometric center opposite the first side.

4. The neuromodulation device of claim 3, wherein a trace of the first set of traces closest to the geometric center has a highest impedance, and wherein another trace of the first set of traces furthest from the geometric center has a lowest impedance.

5. The neuromodulation device of claim 3, wherein a trace of the first set of traces closest to the geometric center has a first diameter, and wherein another trace of the first set of traces furthest from the geometric center has a second diameter greater than the first diameter.

6. The neuromodulation device of claim 1, wherein each trace in the first set of traces and the second set of traces includes at least one curved portion.

7. The neuromodulation device of claim 6, wherein the at least one curved portion is semi-circular.

8. The neuromodulation device of claim 6, wherein the at least one curved portion is circular.

9. The neuromodulation device of claim 1, wherein the first set of traces includes at least three traces, and wherein the second set of traces includes at least three traces.

10. The neuromodulation device of claim 1, wherein the first set of traces are interconnected to form a first trace mesh, and wherein the second set of traces are interconnected to form a second trace mesh. 30 168329311.1PATENT Attorney Docket No. 125847.8039.WO0111. The neuromodulation device of claim 1, wherein the first electrode further comprises a first pair of parallel bars connected to ends of the first bar so as to define a periphery of the first electrode in a C-shape.

12. A device for treating a living body through electrical neuromodulation, the device comprising: a controller configured to generate pulse waveforms; and a pair of electrodes through which the pulse waveforms are applied to the living body, wherein each electrode of the pair of electrodes includes: an input / output trace that extends from a central portion of the device to a distal end of the device, and then along the distal end of the device, wherein the input / output trace delivers electrical current to the distal end, and a set of conductive traces that are connected to the input / output trace at the distal end of the device, to allow the electrical current to flow back towards the central portion of the device.

13. The device of claim 12, wherein thicknesses of the set of conductive traces decrease as distance from the distal end increases to increase impedance along a path of the electrical current.

14. The device of claim 12, wherein the pair of electrodes are formed as different portions of a pad that is comprised of conductive hydrogel.

15. The device of claim 12, wherein the pair of electrodes each include a pad that is comprised of conductive hydrogel, wherein the pads of the respective electrodes are separate from one another.

16. An electrode for a neuromodulation device, the electrode comprising: a first bar defining a first portion of a periphery of the electrode; and 31 168329311.1PATENT Attorney Docket No. 125847.8039.WO01traces electrically connected to the first bar and extending in a first direction perpendicular to the first bar and away from the first bar, wherein the traces decrease in diameter in the first direction.

17. The electrode of claim 16, wherein the first bar is equipotential its length.

18. The electrode of claim 16, further comprising a second bar defining a second portion of the periphery of the electrode and a third bar defining a third portion of the periphery, wherein the second bar is electrically connected to a first end of the first bar, wherein the third bar is electrically connected to a second end of the first bar, wherein the second bar and the third bar are parallel to one another, and wherein the first bar is perpendicular to the second bar and the third bar.

19. The electrode of claim 18, wherein the first bar, the second bar, and the third bar are positioned in a C-shape.

20. The electrode of claim 16, wherein each of the traces includes at least one curved portion.

21. The electrode of claim 16, wherein the traces are at least three traces.

22. The electrode of claim 16, wherein the traces are interconnected to form a trace mesh.

23. The electrode of claim 16, further comprising a gel pad electrically connected with the traces, wherein the gel pad is configured to be placed in contact with a user’s skin.

24. An electrode for a neuromodulation device, the electrode comprising: 32 168329311.1PATENT Attorney Docket No. 125847.8039.WO01a first bar defining a first portion of a periphery of the electrode, wherein the first bar extends in a first direction; a first trace electrically connected to the first bar, wherein the first trace extends parallel to the first direction, and wherein the first trace has a first impedance along its length; and a second trace electrically connected to the first bar via the first trace, wherein the second trace extends parallel to the first direction, and wherein the second trace has a second impedance along its length different than the first impedance.

25. The electrode of claim 24, wherein the first bar is equipotential along its length.

26. The electrode of claim 24, further comprising a second bar defining a second portion of the periphery of the electrode and a third bar defining a third portion of the periphery, wherein the second bar is electrically connected to a first end of the first bar, wherein the third bar is electrically connected to a second end of the first bar, wherein the second bar and the third bar are parallel to one another, and wherein the first bar is perpendicular to the second bar and the third bar.

27. The electrode of claim 26, wherein the first bar, the second bar, and the third bar are positioned in a C-shape.

28. The electrode of claim 24, wherein both the first trace and the second trace includes at least one curved portion.

29. The electrode of claim 24, wherein the first trace and the second trace are interconnected to form a trace mesh.

30. The electrode of claim 24, further comprising a gel pad in electrically connected with the first trace and the second trace, wherein the gel pad is configured to be placed in contact with a user’s skin. 33 168329311.1PATENT Attorney Docket No. 125847.8039.WO0131. The electrode of claim 24, wherein the first trace has a first diameter, and wherein the second trace has a second diameter different than the first diameter.

32. An electrode for a neuromodulation device, the electrode comprising: a first bar defining a first portion of a periphery of the electrode, wherein the first bar is configured to convey current from a controller; and a gel pad electrically connected with the first bar, wherein the first bar is in electrical communication with a first peripheral edge of the gel pad, wherein the first bar provides an equipotential electrical connection to the gel pad along an entire length of the first bar, and wherein electrical current is configured to flow through a user’s body in a flow direction toward a second peripheral edge of the gel pad opposite the first peripheral edge.

33. The electrode of claim 32, comprising a second bar defining a second portion of the periphery of the electrode, wherein the second bar is electrically connected to the first bar, wherein the second bar is perpendicular to the first bar.

34. The electrode of claim 33, comprising a third bar defining a third portion of the periphery of the electrode, wherein the third bar is electrically connected to the first bar, wherein the third bar is perpendicular to the first bar and parallel to the second bar.

35. The electrode of claim 34, wherein the first bar, the second bar, and the third bar are positioned in a C-shape.

36. The electrode of claim 32, further comprising traces electrically connected to the first bar, wherein the traces decrease in diameter in the flow direction. 34 168329311.1PATENT Attorney Docket No. 125847.8039.WO0137. The electrode of claim 32, further comprising traces electrically connected to the first bar, wherein the traces increase in impedance in the flow direction.

38. A method of neuromodulation treatment with a neuromodulation device comprising a first electrode and a second electrode, the method comprising: positioning the first electrode on the skin of a user at a first location, wherein the first electrode includes a positive impedance gradient across an area of the first electrode extending in a first direction toward the second electrode such that an impedance of the first electrode closer to the second electrode is greater than an impedance of the first electrode further from the second electrode; positioning the second electrode on the skin of the user at a second location spaced from the first location, wherein the second electrode includes a positive impedance gradient across an area of the second electrode extending in a second direction toward the first electrode such that an impedance of the second electrode closer to the first electrode is greater than an impedance of the second electrode further from the first electrode; and passing current into the first electrode, though a body of the user, and into the second electrode.

39. The method of claim 38, wherein the first electrode comprises: a first bar disposed at a distal end of the first electrode with respect to a geometric center between the first electrode and the second electrode; and first traces extending across the area of the first electrode, wherein the first traces decrease in diameter in the first direction. 35 168329311.1PATENT Attorney Docket No. 125847.8039.WO0140. The method of claim 39, wherein the second electrode comprises: a second bar disposed at a distal end of the second electrode with respect to the geometric center; and second traces extending across the area of the second electrode, wherein the second traces decrease in diameter in the second direction.

41. The method of claim 38, wherein the first electrode comprises a first gel pad, and wherein the second electrode comprises a second gel pad, wherein positioning the first electrode on the skin at the first location comprises placing the first gel pad on the skin at the first location, and wherein positioning the second electrode on the skin at the second location comprises placing the second gel pad on the skin at the second location.

42. The method of claim 38, wherein the first electrode comprises a first bar defining a distalmost periphery of the first electrode furthest from the second electrode, wherein the first bar extends perpendicular to the first direction, and wherein the first bar is equipotential along its length.

43. The method of claim 42, wherein the second electrode comprises a second bar defining a distalmost periphery of the second electrode furthest from the first electrode, wherein the second bar extends perpendicular to the second direction, and wherein the second bar is equipotential along its length.36 168329311.1

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