Waveform generator for neuromodulation device and method for use

Abstract

A device may include a first electrode and a second electrode configured to be worn on the skin of a living body. The device may include a non-transitory memory storing a plurality of waveforms. The device may include a digital-to-analog convertor (DAC) comprising two or more channels and an analog switch configured to switch between the two or more channels. The device may include a controller configured to generate a pulse waveform for delivering electrical current from the power source to the living body via the first electrode by: streaming one of the plurality of waveforms from the non- transitory memory, outputting digital signals to the DAC based on the streamed waveform, and controlling a state of the analog switch based on the streamed waveform.

Description

PATENT Attorney Docket No. 125847.8040.WO01WAVEFORM GENERATOR FOR NEUROMODULATION DEVICE AND METHOD FOR USE CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Application No. 63 / 616,261, titled “Waveform Generator for Neuromodulation Device and Method for Use” and filed December 29, 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. Meanwhile, conventional TENS is 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.PATENT Attorney Docket No. 125847.8040.WO01BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 illustrates a conventional example of a neuromodulation device for applying TENS.

[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 electrical arrangement for a neuromodulation device, according to some embodiments.

[0010] Figure 6 illustrates exemplary outputs of an electrical arrangement for a neuromodulation device, according to some embodiments.

[0011] Figure 7 is a block diagram illustrating a device for generating an electrical pulse from a waveform file, according to some embodiments

[0012] Figure 8 is a block diagram illustrating a device for generating an electrical pulse from a waveform file, according to some embodiments.

[0013] Figure 9 is a flow diagram for a method of operating a neuromodulation device, according to some embodiments.

[0014] Figure 10 is a flow diagram for a method of operating a neuromodulation device, according to some embodiments.

[0015] Figure 11 is a flow diagram for a method of operating a neuromodulation device, according to some embodiments.

[0016] 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 departingPATENT Attorney Docket No. 125847.8040.WO01from the principles of the technology. Accordingly, although specific embodiments are shown in the drawings, the technology is amenable to various modifications. DETAILED DESCRIPTION

[0017] 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, reduced treatment amplitude of a neuromodulation signal may result in less effectiveness for therapeutic treatment.

[0018] Introduced here are neuromodulation devices 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 of operating the same – according to exemplary embodiments herein are configured to improve pain relief while avoiding user discomfort.

[0019] In addition to the above, many conventional neuromodulation devices for applying TENS utilize static waveforms that are immutable. Some such TENS devices do not offer adjustability of the waveforms, or if they do offer adjustability, only allow modification of the constant frequency or amplitude of the waveform. These static waveforms do not provide effective TENS treatment for all circumstances. For example, different types of pain may be more effectively treated by different types of waveforms. In somePATENT Attorney Docket No. 125847.8040.WO01circumstances, different parts of the body or different nerve types may respond differently to different waveforms. It has been shown that waveforms having specific shapes in different portions of the waveform may be more therapeutically effective than the static waveforms employed in conventional neuromodulation devices.

[0020] As further discussed below, the neuromodulation devices introduced here can overcome the deficiencies of conventional neuromodulation devices that implement static waveforms for TENS treatments. Specifically, neuromodulation devices according to exemplary embodiments herein may apply waveforms that have different portions of a waveform with different amplitude levels to provide more effective and comfortable TENS treatments. Some such neuromodulation devices may be configured to apply a plurality of different waveforms having differing shapes depending on the particular body part, pain type, nerve type, and user comfort level, among other parameters. Additionally, neuromodulation devices according to exemplary embodiments herein may apply multiple different waveforms in sequence as a part of a more therapeutically effective treatment. In some embodiments, different parameters of a wavelet forming a waveform may be adjustable to ensure application of waveforms providing effective treatment. For example, periods of a portion of a wavelet may be adjustable, amplitudes of a portion of a wavelet may be adjustable, shapes of a portion of a wavelet may be adjustable, etc. In some embodiments, a neuromodulation device may be configured to stream a waveform from a plurality of waveforms stored in a database, for example, on local or remote non-transitory memory. A particular waveform may be streamed from the database depending on the body part, pain type, nerve type, and user comfort level, among other parameters. The waveforms of the plurality of waveforms may differ from one another in one or more ways, for example, with different portion amplitudes, shapes, periods, etc.

[0021] In addition to the above, as many conventional neuromodulation devices are configured to apply static waveforms to a living body, they have electrical hardware configured to generate only that static waveform. However, as noted above, the inventors have appreciated the benefits of aPATENT Attorney Docket No. 125847.8040.WO01neuromodulation device which can be configured to apply different waveforms depending on the circumstances of treatment, including, but not limited to, body part, pain type, nerve type, and user tolerance. Additionally, neuromodulation devices may apply different waveforms in sequence as a part of a TENS treatment plan. Therefore, a neuromodulation device that may be capable of applying different waveforms depending on such circumstances may be desirable. Conventional neuromodulation devices do not have the electrical hardware capable of generating multiple waveforms. Moreover, conventional approaches to variable waveform generation involve complex electrical hardware, which can not only be difficult to implement in neuromodulation devices (e.g., due to power consumption, heat generation, etc.) but also impractical from a cost perspective. Neuromodulation devices are generally designed to be used by a wide variety of individuals for addressing a wide variety of issues, and therefore developing neuromodulation devices that can be offered at lower cost is desirable as it makes the benefits more widely accessible. As such, cost and complexity can be significant considerations when designing neuromodulation devices.

[0022] Introduced here are neuromodulation devices that are configured to stream different waveform files from memory to apply the different waveforms to a living body. A plurality of waveforms may be stored in and then retrieved from non-transitory memory onboard the neuromodulation device via direct memory access (DMA). The neuromodulation device may include a controller or discrete electrical design that is configured to read the stored waveform and generate signal outputs to control generation of the waveform as an output of the neuromodulation device. This arrangement may allow for less complex electrical hardware while still allowing for complex waveform shapes with varying parameters. Such an arrangement may also allow for waveform playlists to be easily created and applied to provide differing waveforms in sequence as a part of a TENS treatment. Such an arrangement may also allow a single neuromodulation device to adapt to different circumstances, such as body part type, pain type, nerve type, and user tolerance by streaming a waveform file corresponding to the particular circumstances. Finally, such anPATENT Attorney Docket No. 125847.8040.WO01arrangement may allow a neuromodulation device to apply updated waveforms over time as methods of TENS treatments evolve. For example, a TENS device may receive new waveform files from a remote device such as a mobile phone or a remote server.

[0023] Given a neuromodulation device can dynamically generate an electrical signal based on a waveform data structure, a neuromodulation device according to embodiments herein can: Apply different waveforms having one or more different parameters; Effectively treat different body parts or nerve types in a living body to reduce pain; Allow for adjustability of waveforms to conform to user tolerance to improve user comfort and maintain therapeutic effectiveness; Apply sequences of differing waveforms according to a treatment plan; and Allow for the updating of electrical signals applied by the neuromodulation device over time.

[0024] In some embodiments, a waveform file may be a data structure that includes multiple arrays of values, each of which is associated with one or more frames. The data structure may include a plurality of frames in a sequence, where a controller accessing the waveform file may output digital signals in sequence according to each sequential frame. Each value in the array of values associated with each frame may correspond to a digital output from the controller. Accordingly, the controller may receive each frame, and output digital signals according to the values associated with that frame. In this manner, a waveform file may be “streamed” from memory, as each frame sequentially modifies the outputs of the controller. As used herein, “streaming” refers to accessing a waveform file and processing each frame and the associated array of values of the waveform file in sequence. In some embodiments, hardware interrupts like a hardware timer may be employed to switch between sequential frames in a waveform file. In some embodiments, a waveform file may include at least one parameter of the waveform, which may include an output limit, aPATENT Attorney Docket No. 125847.8040.WO01frame period, a frequency modulation, or an amplitude modulation. In some embodiments, a waveform file may include a first array of values corresponding to digital outputs to a digital-to-analog converter (DAC) for each frame, and a second array of values corresponding to logic signals output to an analog switch. In some embodiments, a waveform file may be streamed from local memory by direct memory access (DMA).

[0025] In some embodiments, a neuromodulation device may include a digital to analog converter (DAC) including two or more channels. The DAC may be configured to output different analog signals based on digital signals output from a controller. The neuromodulation device may also include an analog switch. The analog switch may switch between the two or more channels of the DAC, and may be controlled by digital signals from the controller. The digital signals output from the controller based on a waveform file may allow a waveform to be piecewise constructed from the outputs of the DAC by switching the analog switch between the two or more channels. Such an arrangement may allow the neuromodulation device to apply a plurality of different waveforms according to corresponding waveform files streamed from memory. In some embodiments, a neuromodulation device may employ hardware interrupts to trigger outputs of digital signals based on a waveform file. For example, a neuromodulation device may include a hardware timer or frame sync input signal that provides an interrupt trigger to a controller to convert waveform data to output of one or more digital signals. Such an arrangement may reduce compute operations performed by a controller, which may improve response speed and allow for more complex waveforms to be generated by the neuromodulation device.

[0026] Given a neuromodulation device including a DAC and an analog switch, a neuromodulation device according to embodiments herein can: Dynamically generate and apply different waveforms having one or more different parameters; Stream waveform files to generate analog waveform signals using digital signal from controller;PATENT Attorney Docket No. 125847.8040.WO01Generate a waveform in a piecewise by switching between output channels of the DAC; and Maintain low device cost and complexity compared to other electrical hardware implementations for applying different waveforms.

[0027] While embodiments of neuromodulation devices herein include a DAC and an analog switch, in other embodiments other arrangements may be employed to generate waveforms according to a waveform file. In some embodiments, a neuromodulation device may include a function generator configured to generate different waveforms according to a waveform file and computer program. In some embodiments, a neuromodulation device may include a field-programmable gate array (FPGA) that is configured to generate waveforms according to a computer program. An advantage of an FPGA arrangement is the customizability by a computer program. However, FPGAs may have a high unit cost that may be impractical for reasons discussed above. In other embodiments, a neuromodulation device may include an application- specific integrated circuit (ASIC) configured to generate waveforms according to a waveform file. An advantage of the ASIC approach is low unit cost for the complexity provided, but such an arrangement has high development costs that may be impractical for reasons discussed above. However, while such arrangements are contemplated, arrangements described herein have advantages including circuit simplicity and lower cost.

[0028] In some embodiments, a neuromodulation device may include a DAC having exactly two channels. In other embodiments, a neuromodulation device may include a DAC having no more than five channels. In some embodiments, a neuromodulation device may include a DAC having no more than two channels. In some embodiments, a neuromodulation device may include multiple DACs.

[0029] Neuromodulation devices according to embodiments herein may employ waveform files to generate electrical signals that are applied to a living body based on the data stored in the waveform files. In some embodiments, a plurality of waveforms files may be stored in non-transitory memory onboardPATENT Attorney Docket No. 125847.8040.WO01the neuromodulation device. In some embodiments, waveform files may be downloaded onto a neuromodulation device from a remote device, such as a mobile phone or a remote server. In this manner, waveform files streamed on a neuromodulation device may be updated or changed over time. In some embodiments, a plurality of waveform files stored in memory of a neuromodulation device may include waveforms from a variety of different sources.

[0030] 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. While embodiments are generally described in the context of human bodies, aspects of those embodiments may be similarly applicable if the living bodies being treated are animal bodies. Accordingly, electrodes and neuromodulation devices according to embodiments herein may be used in connection with any living body.

[0031] 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 embodiments, a first electrode and a second electrode may be connected to a controller via respective flexible wires.

[0032] 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.

[0033] Embodiments may be described in the context of computer- executable instructions for the purpose of illustration. However, aspects of thePATENT Attorney Docket No. 125847.8040.WO01approach could be implemented via hardware or firmware instead of, or in addition to, software. Terminology

[0034] 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.

[0035] 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.”

[0036] 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.

[0037] 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.

[0038] 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.PATENT Attorney Docket No. 125847.8040.WO01Overview of Conventional Neuromodulation Device

[0039] Figure 1 illustrates a conventional example of a neuromodulation device 100. 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 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.

[0040] 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 device 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.

[0041] Conventional neuromodulation devices like that of Figure 1 are configured to apply static waveforms. That is, the waveform applied by the neuromodulation device is not variable in shape and other parameters that may change the effectiveness of a TENS treatment depending on certain circumstances, such as body part type, pain type, nerve type, and user tolerance. Accordingly, with conventional neuromodulation devices, typically separate devices may be configured to treat different body parts or pain types, and the waveforms are not adjustable.PATENT Attorney Docket No. 125847.8040.WO01

[0042] As discussed further below, devices and methods described with reference to embodiments herein may address the inflexibility of conventional neuromodulation devices like those shown in Figure 1. Accordingly, neuromodulation devices and methods described herein may not only provide for more therapeutically effective treatments, but may also allow a single device to apply TENS treatment for a variety of different user conditions. Overview of Neuromodulation Device and Method of Operation

[0043] 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. An example of a control electronics module will be discussed with reference to Figure 5. In some embodiments, the control electronics module 202 may include a memory storing a plurality of waveforms. 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. The control electronics module 202 may receive input indicative of a request to initiate an electrical neuromodulation operation, in some embodiments. 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), infraredPATENT Attorney Docket No. 125847.8040.WO01(e.g., Infrared Data Association (IrDA) associated wireless communications), etc. The communication interface module 208 may allow a neuromodulation device to access waveform files stored on remote devices, such as a mobile phone or remote server.

[0044] The control electronics module 202 may provide any number of details, feedback, or information about its operation through an indicator module 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.

[0045] 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.

[0046] The pulse generating electronics module 210 may include various components, including, but not limited to, switching circuits, digital-to-analog converters (DACs), switches, and registers, which are configured to producePATENT Attorney Docket No. 125847.8040.WO01the electric pulses with controlled shape and amplitude as described herein. Examples of a pulse generating electronics module 210 is discussed further with reference to Figure 5 and 7-8.

[0047] 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, printed 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.

[0048] 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.

[0049] 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 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.

[0050] 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.,PATENT Attorney Docket No. 125847.8040.WO01Bluetooth® 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.

[0051] 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.

[0052] 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.PATENT Attorney Docket No. 125847.8040.WO01

[0053] 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 from 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.

[0054] 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).

[0055] 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.

[0056] 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.

[0057] 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 thePATENT Attorney Docket No. 125847.8040.WO01primary 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 phase 310 which may have its polarity opposite to that of the primary phase 306, as shown.

[0058] 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”).

[0059] 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 peak 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 skinPATENT Attorney Docket No. 125847.8040.WO01capacitance 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 state 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.

[0060] 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.

[0061] 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.

[0062] Figure 5 illustrates an electrical arrangement for a neuromodulation device 500, according to some embodiments. As shown in Figure 5, a neuromodulation device may include a controller 502, which may be a computer processor configured to execute computer readable instructions stored inPATENT Attorney Docket No. 125847.8040.WO01memory. The controller 502 may be configured to output digital signals from one or more pins 503, which in some embodiments may be dedicated serial communication pins and in other embodiments may be general purpose input / output (GPIO) pins. The controller 502 may be configured to access a waveform file stored in memory, for example, by direct memory access. The controller may output digital signals from the one or more pins 503 based on values stored in the accessed waveform file. The digital signals from the controller 502 may be employed to control other electrical components of the neuromodulation device 500 to ultimately generate the waveform according to the values in the waveform file and apply the waveform as an electrical current to a living body 528.

[0063] As shown in Figure 5, the controller 502 is connected to a digital-to- analog convertor (DAC) 504. Specifically, the controller 502 is configured to send digital signals to the DAC 504 to control analog outputs of the DAC. The DAC 504 of Figure 5 is a two-channel DAC, including a first channel 505 and a second channel 505. In some embodiments, the DAC 504 is an 8-, 10-, or 12- bit DAC. Digital signals from the controller 502 are configured to control an analog output of the first channel 505 and the second channel 506. In some embodiments, the controller 502 is configured to write values to the DAC. The outputs from the first channel 505 and the second channel 506 are employed to construct an overall waveform output. In some embodiments as shown in Figure 5, the electrical arrangement also includes a minimum voltage input 508 (e.g., a first fixed voltage value) and a maximum voltage input 510 (e.g., a second fixed voltage value). The minimum voltage input 508 may represent a minimum, approximately zero voltage applied as a part of a waveform, for example, corresponding to a minimum amplitude of the waveform. The maximum voltage input 510 may correspond to a maximum current of the power source, as applied as a part of a waveform, for example, corresponding to a maximum amplitude of the waveform. The minimum voltage input 508 and the maximum voltage input 510 represent constant voltage signals that may contribute to an ultimate waveform applied as an electrical current to the living body 528. The minimum voltage input 508 and the maximum voltage input 510PATENT Attorney Docket No. 125847.8040.WO01may originate from a power source of the neuromodulation device. In some other embodiments, additional or different fixed voltage signals may be employed. For example, an intermediary constant voltage signal between the minimum voltage input 508 and the maximum voltage input 510 may be employed, in some embodiments. These constant signals may be utilized by the controller 502 to generate an overall waveform, as discussed further below. The output of the DAC 504 may be controlled based on a timer or interrupt signal. In some embodiments, for every frame of a waveform file, corresponding to a particular frame period, the first DAC channel 505 and the second DAC channel 506 may have an assigned state depending on their respective values within the frame. For sequential frames, the outputs of the first DAC channel 505 and the second DAC channel 506 may change or remain the same according to the respective values in each frame. Therefore, as a waveform including a plurality of frames is streamed, the outputs of the first DAC channel and the second DAC channel may be updated in each frame. Depending on the waveform, the plurality of frames could be sequenced so that each frame only contains data for one DAC channel.

[0064] As shown in Figure 5, the neuromodulation device 500 includes an analog switch 512. The analog switch 512 of the depicted embodiment includes four inputs, corresponding to the first DAC channel 505, second DAC channel 506, minimum voltage input 508, and maximum voltage input 510. The analog switch of Figure 5 includes a single switch output 615. The analog switch 512 is configured to switch between the four inputs according to digital signals received from the controller 502. Accordingly, the output 615 of the analog switch is an analog signal according to one of the four inputs. The overall waveform 516 generated by this switching, as well as the control of the outputs of the DAC 504 may therefore have a variety of shapes that may be built piecewise in sequence. That is, as the switch 512 switches between inputs, the waveform 516 may be constructed in sequential portions. In this manner, an analog waveform having any desired parameters or shape may be produced by the neuromodulation device according to digital signals from the controller 502. The state of the switch may be controlled based on a timer or interruptPATENT Attorney Docket No. 125847.8040.WO01signal. In some embodiments, for every frame of a waveform file, corresponding to a particular frame period, the analog switch may have an assigned state depending on the value for the switch within the frame. For sequential frames, the state of the analog switch 512 may change or remain the same according to the switch value in each frame. Therefore, as a waveform including a plurality of frames is streamed, the input which is passed through the switch 512 to the switch output 615 is updated for each frame. As shown in the example of Figure 5, the waveform 516 is composed of multiple inputs, with the analog switch moving from position 1, to position 0, to position 2, to position 1, to position, and to position 3 based on a sequence of frames.

[0065] In some embodiments as shown in Figure 5, the waveform 516 that is output by the analog switch 512 is not directly applied to the living body 528. Rather, the waveform 516 is employed as a reference waveform in feedback module 518. The voltage of the waveform 516 is employed by the feedback module 518 to control an amount of current flowing through the living body 528 via electrodes. The current flowing to the living body 528 may flow from a power supply circuit 526 according to the reference waveform 516 provided to the feedback module 518.

[0066] In some embodiments as shown in Figure 5, the neuromodulation device 500 includes a register 514 that is connected to the controller 502. Note that the register 514 could be integrated into the analog switch component of the neuromodulation device 500, or the register 514 could be separate from the analog switch component of the neuromodulation device 500. The register 514 is configured to receive digital signals 513 from the controller 502 and convert them into logic signals. Specifically, the register 514 is configured to convert bits of a byte into a logic signal. The register 514 is connected to the analog switch 512. The register sends logic signals 517 to the analog switch 512 to control the state of the analog switch 512. In some embodiments, the register 514 is a shift register. In some embodiments, the register 514 may be optional and the states of the various switches may be controlled directly by outputs from GPIO pins of the controller 502. In some such embodiments, hardware timers may be employed to trigger GPIO pin output to the switches. EliminationPATENT Attorney Docket No. 125847.8040.WO01of the register 514 may provide a lower cost unit due to elimination of the register hardware. However, the firmware for the controller 502 may be more complex in such instances and may occupy processing cycles that may be useful for other operations.

[0067] In some embodiments as shown in Figure 5, the neuromodulation device 500 includes a switching circuit 520. The switching circuit 520 is configured to control the direction of current flow through the living body, and specifically is a circuit configured to switch the polarity of the voltage applied to the living body 528 through electrodes. The switching circuit includes a first switch 524A, a second switch 524B, a third switch 524C, and a fourth switch 524D. The switching circuit of the embodiment of Figure 5 is an H-bridge. The switching circuit includes edge delay logic 519 which receives logic signals from the register 514 and sends switching circuit logic signals 521 to the switching circuit 520 controlling the state of each of the switches. In the example of Figure 5, the current flows in one direction (e.g., from a first electrode to a second electrode and right on the page) when the first switch 524A and third switch 524C are closed. The current flows in a second opposite direction (e.g., from the second electrode to the first electrode and left on the page) when the second switch 524B and the fourth switch are closed. In some embodiments, the switching circuit may be controlled by a switching circuit internal circuit instead of by logic signals from the register 514. Such an arrangement may provide simpler firmware for a controller and fewer components, but may be higher cost and rely on a single source to drive the switching circuit. In some embodiments, the switching circuit 520 may be optional. In some such embodiments, a dual power supply circuit 526 may be employed so that current may still be passed in two directions across electrodes. Such a dual power supply circuit 526 may generate two different output voltages. A dual power supply circuit arrangement may provide simpler firmware for a controller and fewer components, but a more complex power supply circuit.

[0068] In some embodiments, rather than a DAC 504, a neuromodulation device may be configured to generate analog signals to contribute to an overall waveform by pulse width modulation (PWM). In such an arrangement, GPIOPATENT Attorney Docket No. 125847.8040.WO01pins of the controller 502 may be configured to output analog signals based on PWM to the analog switch 512. In such an arrangement, additional voltage inputs and a larger analog switch 512 may be employed than in the arrangement shown in Figure 5. In some cases, use of PWM via GPIO pins may achieve lower cost and provide a smaller circuit. However, such an arrangement may be slower than other arrangements discussed herein and may also keep the controller 502 busy with waveform generation, limiting available processing cycles for other operations.

[0069] In some embodiments, the reference waveform 516 may be produced as an output of a DAC without an analog switch 512. That is, in some embodiments the analog switch 512 may be optional. In such arrangements, a DAC with appropriate speed may generate analog signals in response to digital signals from the controller 502, and these analog signals may comprise the waveform 516 used as reference to apply current to the living body 528. In such embodiments, a waveform file may still provide values employed by a controller 502 to output digital signals to control the output of the DAC.

[0070] Figure 6 illustrates exemplary outputs 600 of an electrical arrangement for a neuromodulation device, according to some embodiments. Figure 6 depicts representative signals of various components in the circuit shown and described in Figure 5. The signals 602, 604, 606, and 608 represent the four switching circuit logic signals 521 controlling the state of the switches to control current flow through the living body 528. Signal 610 represents the output from the analog switch 512, and represents the reference waveform 516. Signal 612 represents the treatment current through the living body 528. That is, the signal 612 is the actual waveform applied to the living body 528 based on the waveform 516 that is output from the analog switch 512. Signal 614 is the voltage measured at the feedback module 518. As shown in Figure 6, the use of a two-channel DAC and an analog switch allows complex waveforms to be applied as a part of a TENS treatment. Specifically, the shape, amplitude, and period of various portions of a waveform may be changed according to digital signals produced based on values in a waveform file.PATENT Attorney Docket No. 125847.8040.WO01

[0071] Figure 7 is a block diagram illustrating a device 700 for generating an electrical pulse from a waveform file, according to some embodiments. The blocks shown in Figure 7 may be internal peripherals of a controller such as a serial bus controller 710, in some embodiments. In other embodiments, the blocks shown in Figure 7 may be external components interfaced with a controller. As shown in Figure 7, an interrupt source 702 is configured to generate an interrupt signal. The interrupt source may be a hardware timer or frame sync input signal, in some embodiments. The interrupt source is configured to write a trigger 704 to the serial bus controller 710.

[0072] Waveform data 706 from a waveform file is streamed to the serial bus controller 710 through direct memory access 708 (DMA). In some embodiments, the serial bus controller 710 may identify one of a plurality of waveforms in memory. The waveform data may include a first array of values corresponding to digital outputs of the serial bus controller 710. As discussed herein, the waveform data may include a plurality of frames, each being associated with particular digital outputs from the serial bus controller 710. The interrupt signal from the interrupt source 702 may be employed to retrieve a next sequential frame from the waveform data 706 and change the digital outputs of the serial bus controller 710. Based on the waveform data, the serial bus controller 710 outputs digital signals 712 to a shift register 714. The serial bus controller 710 may write values to the shift register 714. In some embodiments, these digital signals 712 may be a DMA write. The shift register in turn outputs control signals 716 that are logic signals configured to control the state of switches of the device, such as an analog switch and / or a switching circuit (e.g., H-bridge). Thus, the shift register 714, upon having values written therein, is configured to output one or more logic signals. Accordingly, the diagram shown in Figure 7 illustrates how waveform data is streamed and employed to output logic signals controlling the state of various switches to generate a waveform applied to a living body.

[0073] Figure 8 is a block diagram illustrating a device 800 for generating an electrical pulse from a waveform file, according to some embodiments. The diagram of Figure 8 is similar to that in Figure 7, with the exception that thePATENT Attorney Docket No. 125847.8040.WO01device in Figure 8 is configured to control analog voltage outputs from a DAC 814. As in Figure 7, the blocks shown in Figure 8 may be internal peripherals of a controller such as a serial bus controller 810, in some embodiments. In other embodiments, the blocks shown in Figure 8 may be external components interfaced with a controller. In some embodiments, the serial bus controller 810 may be the same serial bus controller 710 of Figure 7. For example, the components of Figures 7 and 8 may be integrated into a single circuit.

[0074] As shown in Figure 8, the device includes an interrupt source 802. The interrupt source 802 is configured to generate an interrupt signal. The interrupt source may be a hardware timer or frame sync input signal, in some embodiments. The interrupt source is configured to write a trigger 804 to the serial bus controller 810.

[0075] The serial bus controller 810 can receive waveform data 806 from memory. In some embodiments, the serial bus controller 810 may identify one of a plurality of waveforms in memory. In some embodiments, the serial bus controller may receive the waveform data by DMA 808. The waveform data 806 may include a second array of values corresponding to digital outputs of the serial bus controller 810. As discussed herein, the waveform data may include a plurality of frames, each being associated with particular digital outputs from the serial bus controller 810. The interrupt signal from the interrupt source 802 may be employed to retrieve a next sequential frame from the waveform data 806 and change the digital outputs of the serial bus controller 810. Based on the waveform data, the serial bus controller 810 outputs digital signals to a DAC 814, for example, via a write 812 operation. The DAC 814 outputs analog voltages 816 in response to the digital signals from the serial bus controller 810. In some embodiments, the analog voltages 816 may be a pair of voltage signals, similar to the arrangement described with reference to Figure 5. Thus, the DAC 814, upon having values written therein, is configured to output a pair of analog voltages 816. In this manner, analog signals can be produced according to waveform data 806. Accordingly, the diagram shown in Figure 8 illustrates how waveform data is streamed and employed to generate analogPATENT Attorney Docket No. 125847.8040.WO01voltage signals that may form portions of an overall waveform applied to a living body.

[0076] The devices of Figures 7 and 8 may be combined to generate an overall waveform applied to a living body. In some embodiments, waveform data may include additional parameters corresponding to a waveform. For example, the waveform parameters included in waveform data may include, but are not limited to, output limit, a frame period, a frequency modulation, or an amplitude modulation. These parameters may set the general attributes of a waveform, whereas the arrays of values of the waveform data are employed to change the outputs of various components to generate the waveform, such as a DAC and an analog switch.

[0077] Figure 9 is a flow diagram for a method 900 of operating a neuromodulation device, according to some embodiments. In act 902, the method includes streaming one of a plurality of waveforms stored on non- transitory memory. In some embodiments, streaming one of a plurality of waveforms may include obtaining a first array of values and a second array of values associated with a frame of a plurality of frames. In act 904, the method includes outputting digital signals to a digital-to-analog converter (DAC) comprising two channels based on the streamed waveform to the DAC to control the output of the two channels. In some embodiments, the first array of values may be employed to write digital signals to the DAC to generate a pair of analog voltage signals. In act 906, the method includes controlling a state of an analog switch based on the streamed waveform. In some embodiments, the second array of values may be employed to write digital signals to a register to generate logic signals that change the state of the analog switch. In some embodiments, changing the state of the analog switch may control which of the pair of analog voltages from the DAC contribute to an output waveform. In act 908, the method includes applying a pulse waveform to the first electrode and the second electrode.

[0078] Figure 10 is a flow diagram for a method 1000 of operating a neuromodulation device, according to some embodiments. In act 1002, the method includes streaming a first waveform of a plurality of waveforms storedPATENT Attorney Docket No. 125847.8040.WO01on non-transitory memory. In act 1004, the method includes outputting digital signals to a DAC having two channels based on the streamed first waveform to control the output of the two channels. The output of a first channel of the two channels may be a first voltage, and the output of a second channel of the two channels may be a second voltage. In block 1006, the method includes controlling a state of an analog switch connected to the DAC based on the streamed first waveform. In some embodiments, controlling the state of the analog switch may include outputting digital signals to a shift register connected to the DAC to generate logic signals sent to the analog switch. The analog switch may move to a first state based on the first streamed waveform. In block 1008, the method includes applying a first pulse waveform to a first electrode and a second electrode. The first pulse waveform may be applied based in part on the first voltage, second voltage, and the first state of the analog switch. That is, an output based on the first voltage, second voltage, and first state of the analog switch may form a portion of a waveform. In some embodiments, applying the first pulse waveform includes outputting a reference waveform based on the first voltage, second voltage, and first state of the switch and applying current to the first electrode and the second electrode based on the reference waveform.

[0079] In act 1010, the method includes streaming a second waveform of a plurality of waveforms stored on non-transitory memory. The streamed second waveform may have values and / or parameters different than the streamed second waveform. In act 1012, the method includes outputting digital signals to the DAC based on the streamed second waveform to control the output of the two channels. The output of a first channel of the two channels may be a third voltage, and the output of a second channel of the two channels may be a fourth voltage. In block 1014, the method includes controlling a state of an analog switch connected to the DAC based on the streamed second waveform. The analog switch may move to a second state based on the first streamed waveform. In block 1016, the method includes applying a second pulse waveform to the first electrode and the second electrode. The second pulse waveform may be applied based in part on the third voltage, fourth voltage, andPATENT Attorney Docket No. 125847.8040.WO01the second state of the analog switch. That is, an output based on the third voltage, fourth voltage, and second state of the analog switch may form a portion of a waveform. In some embodiments, applying the second pulse waveform includes outputting a second reference waveform based on the third voltage, fourth voltage, and second state of the switch and applying current to the first electrode and the second electrode based on the second reference waveform. The second pulse waveform may have one or more different portions or different parameters compared to the first pulse waveform.

[0080] Figure 11 is a flow diagram for a method 1100 of operating a neuromodulation device, according to some embodiments. In act 1102, the method includes streaming one of a plurality of waveforms stored on non- transitory memory. Streaming a waveform may include receiving a sequence of frames each including data. In some embodiments, a waveform may have a first array of values corresponding to a first set of digital signal outputs, and a second array of values corresponding to a second set of digital signal outputs. In act 1104, the method includes outputting a first set of digital signals based on a first frame of a plurality of frames of the streamed waveform to generate a first portion of the pulse waveform. In some embodiments, the first set of digital signals may include a digital signal sent to a DAC, and a digital signal sent to a register connected to an analog switch. In some such embodiments, the digital signal sent to the DAC may be based on a first value within the first array of values, and the digital signal sent to the register may be based on a first value within the second array of values. In act 1106, the first portion of the pulse waveform is applied to a first electrode and a second electrode. In some embodiments, the output of the digital signals in act 1104 may generate a first portion of a reference waveform that is used to deliver current to a living body.

[0081] In act 1108, the method includes outputting a second set of digital signals based on a second frame of the plurality of frames of the streamed waveform to generate a second portion of the pulse waveform. In some embodiments, the second set of digital signals may include a digital signal sent to the DAC, and a digital signal sent to the register connected to the analog switch. In some such embodiments, the digital signal sent to the DAC may bePATENT Attorney Docket No. 125847.8040.WO01based on a second value within the first array of values, and the digital signal sent to the register may be based on a second value within the second array of values. In act 1110, the second portion of the pulse waveform is applied to the first electrode and the second electrode. In some embodiments, the output of the digital signals in act 1108 may generate a second portion of a reference waveform that is used to deliver current to a living body. Remarks

[0082] 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.

[0083] 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.PATENT Attorney Docket No. 125847.8040.WO01

[0084] 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 disclosure of various embodiments is intended to be illustrative, but not limiting,of the scope of the technology as set forth in the following claims.

Claims

PATENT Attorney Docket No. 125847.8040.WO01CLAIMS What is claimed is:

1. A neuromodulation device comprising: a first electrode configured to be worn on the skin of a living body at a first location; a second electrode configured to be worn on the skin of the living body at a second location; a power source; a non-transitory memory storing a plurality of waveforms; a digital-to-analog convertor (DAC) comprising two channels; an analog switch configured to switch between the two channels; and a controller configured to generate a pulse waveform for delivering electrical current from the power source to the living body via the first electrode by: streaming one of the plurality of waveforms from the non- transitory memory, outputting digital signals to the DAC based on the streamed waveform, and controlling a state of the analog switch based on the streamed waveform.

2. The neuromodulation device of claim 1, wherein the analog switch is further configured to switch between a first fixed voltage value and a second fixed voltage value.

3. The neuromodulation device of claim 2, wherein the first fixed voltage corresponds to a maximum current of the power source, and wherein the second fixed voltage is approximately zero voltage.

4. The neuromodulation device of claim 1, further comprising a register connected to the controller and the analog switch, wherein thePATENT Attorney Docket No. 125847.8040.WO01controller is configured to control the state of the analog switch based on the streamed waveform by outputting digital signals to the register.

5. The neuromodulation device of claim 4, further comprising an H-bridge connected to the register, the first electrode, and the second electrode, wherein the H-bridge is configured to control a direction of current flow through the first electrode and the second electrode, and wherein the controller is further configured to control a state of the H-bridge based on the streamed waveform by outputting digital signals to the register.

6. The neuromodulation device of claim 1, wherein each waveform of the plurality of waveforms comprises a plurality of frames in a sequence, wherein the controller is configured to output the digital signals to the DAC and control the state of the analog switch based on the plurality of frames, and wherein each frame of the plurality of frames comprises data indicating: a first voltage of a first channel of the DAC; a second voltage of a second channel of the DAC; and the state of the analog switch.

7. The neuromodulation device of claim 6, wherein the controller comprises an interrupt source, wherein streaming one of the plurality of waveforms comprises: receiving an interrupt trigger from the interrupt source; and retrieving a frame of the plurality of frames of the streamed waveform.

8. The neuromodulation device of claim 1, wherein the DAC is a 8-bit DAC, 10-bit DAC, or 12-bit DAC.

9. The neuromodulation device of claim 1, wherein the controller comprises a plurality of general purpose input / output (GPIO) pins, wherein outputting digital signals to the DAC comprises outputting digital signals to the DAC via one or more of the GPIO pins, andPATENT Attorney Docket No. 125847.8040.WO01wherein controlling the state of the analog switch comprising sending a signal to the analog switch via one of the GPIO pins.

10. The neuromodulation device of claim 1, further comprising an H-bridge connected to the controller the first electrode, and the second electrode, wherein the H-bridge is configured to control a direction of current flow through the first electrode and the second electrode, and wherein the controller is further configured to control the state of the H- bridge based on the streamed waveform.

11. The neuromodulation device of claim 1, wherein the power source is a dual power supply circuit that generates two different output voltages.

12. A device for treating a living body as part of an electrical neuromodulation operation, the device comprising: at least one electrode to be worn against the skin of the living body; a memory that is configured to store waveforms, each of which is represented as a data structure that includes (i) a first array of values and (ii) a second array of values; a controller that, upon receiving input indicative of a request to initiate the electrical neuromodulation operation, is configured to (i) identify one of the waveforms, (ii) write the first array of values associated with the identified waveform into a digital-to-analog converter, and (iii) write the second array of values associated with the identified waveform into a register; the digital-to-analog converter that, upon having the first array of values written therein, is configured to output a pair of voltage signals; the register that, upon having the second array of values written therein, is configured to output a logic signal; and an analog switch that is configured to switch between the pair of voltage signals based on the logic signal, so as to generate the identified waveform in the form of an electrical current.PATENT Attorney Docket No. 125847.8040.WO0113. The device of claim 12, wherein the logic signal is one of a plurality of logic signals output by the register, and wherein the device further comprises: a switching circuit that includes a plurality of switches for controlling a direction that the electrical current will flow through the living body, wherein each of the plurality of switches is controlled by a different one of the plurality of logic signals.

14. The device of claim 12, wherein each data structure further includes a parameter of a corresponding one of the waveforms.

15. The device of claim 14, wherein the parameter is an output limit, a frame period, a frequency modulation, or an amplitude modulation.

16. A method of operating a neuromodulation device, the method comprising: streaming one of a plurality of waveforms stored on non-transitory memory; outputting digital signals to a digital-to-analog convertor (DAC) comprising two channels based on the streamed waveform to control an output of the two channels; controlling a state of an analog switch connected to the DAC, a first electrode, and a second electrode; and applying a pulse waveform to the first electrode and the second electrode.

17. The method of claim 16, wherein controlling the state of the analog switch comprises changing an output of the analog switch between a first channel of the DAC and a second channel of the DAC.

18. The method of claim 17, wherein controlling the state of the analog switch comprises changing an output of the analog switch between thePATENT Attorney Docket No. 125847.8040.WO01first channel, the second channel, a first fixed voltage input, and a second fixed voltage input.

19. The method of claim 18, wherein the first fixed voltage is a maximum voltage of a power source, and wherein the second fixed voltage is approximately zero voltage.

20. The method of claim 16, wherein controlling the state of the analog switch comprises outputting digital signals to a register connected to the analog switch.

21. The method of claim 20, further comprising controlling a state of an H- bridge connected to the register, the first electrode, and the second electrode, wherein the state of the H-bridge is configured to control a direction of current flow through the first electrode and the second electrode, and wherein controlling the state of the H-bridge comprises outputting digital signals to the register.

22. The method of claim 16, wherein each waveform of the plurality of waveforms comprises a plurality of frames in a sequence, wherein each frame of the plurality of frames comprises data indicating: a first voltage of a first channel of the DAC; a second voltage of a second channel of the DAC; and the state of the analog switch.

23. The method of claim 22, wherein streaming one of the plurality of waveforms comprises: receiving an interrupt trigger from an interrupt source; and retrieving a frame of the plurality of frames of the streamed waveform.

24. The method of claim 16, wherein outputting digital signals to the DAC comprises outputting digital signals to the DAC via one or more general purpose input / output (GPIO) pins, and wherein controlling the state ofPATENT Attorney Docket No. 125847.8040.WO01the analog switch comprising sending a signal to the analog switch via one of the GPIO pins.

25. A neuromodulation device comprising: a first electrode configured to be worn on the skin of a living body at a first location; a second electrode configured to be worn on the skin of the living body at a second location; a power source; a non-transitory memory storing a plurality of waveforms; and a controller configured to configured to generate a pulse waveform delivering electrical current from the power source to the living body via the first electrode and the second electrode, wherein the controller is configured to generate the pulse waveform by streaming one of the plurality of waveforms from the non- transitory memory.

26. The neuromodulation device of claim 25, further comprising a digital-to- analog converter (DAC), wherein the DAC is configured to generate an analog voltage based on a digital signal received from the controller, wherein the controller is configured to generate the digital signal based on one of the plurality of waveforms.

27. The neuromodulation device of claim 26, further comprising an analog switch connected to an output of the DAC, wherein the controller is configured to control a state of the analog switch.

28. The neuromodulation device of claim 27, wherein each waveform of the plurality of waveforms comprises a plurality of frames in a sequence, wherein each frame of the plurality of frames comprises data indicating: a voltage output of the DAC; and the state of the analog switch.PATENT Attorney Docket No. 125847.8040.WO0129. The neuromodulation device of claim 25, wherein the controller comprises a function generator configured to generate the pulse waveform.

30. The neuromodulation device of claim 25, wherein the controller comprises a plurality of general purpose input / output (GPIO) pins, and wherein the controller is configured to generate a plurality of pulse voltages based on the streamed waveform with pulse width modulation.

31. The neuromodulation device of claim 30, further comprising an analog switch connected to the GPIO pins, wherein the controller is configured to control a state of the analog switch to switch between the plurality of pulse voltages to apply the pulse waveform at the first electrode and the second electrode.

32. The neuromodulation device of claim 31, wherein each waveform of the plurality of waveforms comprises a plurality of frames in a sequence, wherein each frame of the plurality of frames comprises data indicating: a voltage output for each of the GPIO pins; and the state of the analog switch.

33. A method of operating a neuromodulation device, the method comprising: streaming one of a plurality of waveforms stored on non-transitory memory, wherein each waveform of the plurality of waveforms comprises a plurality of frames, wherein each frame comprises one or more parameters of a pulse waveform; in response to a first interrupt signal, outputting a first set of digital signals based on a first frame of the plurality of frames of thePATENT Attorney Docket No. 125847.8040.WO01streamed waveform to generate a first portion of the pulse waveform; and in response to a second interrupt signal, outputting a second set of digital signals based on a second frame of the plurality of frames of the streamed waveform to generate a second portion of the pulse waveform.

34. The method of claim 33, wherein outputting the first set of digital signals comprises outputting at least one of the first set of digital signals to a digital-to-analog converter (DAC) to cause the DAC to output a first output, and wherein outputting the second set of digital signals comprises outputting at least one of the second set of digital signals to the DAC to cause the DAC to output a second output different than the first output.

35. The method of claim 34, wherein outputting the first set of digital signals comprises outputting one of the first set of digital signals to an analog switch connected to the DAC to change a state of the analog switch, and wherein outputting the second set of digital signals comprises outputting one of the second set of digital signals to the analog switch to change the state of the analog switch.

36. The method of claim 35, wherein the first frame comprises a first voltage output of the DAC and a first state of the analog switch, and wherein the second frame comprises a second voltage output of the DAC and a second state of the analog switch.

37. The method of claim 33, wherein outputting the first set of digital signals comprises outputting the first set of digital signals to a register to cause the register to output a first output, and wherein outputting the second set of digital signals comprises outputting the second set of digital signals to the register to cause the register to output a second output different than the first output.PATENT Attorney Docket No. 125847.8040.WO0138. The method of claim 37, wherein outputting the first set of digital signals comprises outputting one of the first set of digital signals to the register to change a state of an analog switch connected to the register, and wherein outputting the second set of digital signals comprises outputting one of the second set of digital signals the register to change the state of the analog switch.

39. The method of claim 37, wherein outputting the first set of digital signals comprises outputting one of the first set of digital signals to the register to change a state of an H-bridge connected to the register, and wherein outputting the second set of digital signals comprises outputting one of the second set of digital signals the register to change the state of the H-bridge.

40. The method of claim 33, further comprising: in response to outputting the first set of digital signals, applying the first portion of the pulse waveform to a first electrode and a second electrode; and in response to outputting the second set of digital signals, applying the second portion of the pulse waveform to the first electrode and the second electrode.

41. The method of claim 33, wherein outputting the first set of digital signals comprises outputting a first set of voltages via a plurality of general purpose input / output (GPIO) pins by pulse width modulation, and wherein outputting a second set of digital signals comprises outputting a second set of voltages via the plurality of GPIO pins by pulse width modulation.

42. The method of claim 33, wherein the first interrupt signal is from a hardware timer, and wherein the second interrupt signal is from the hardware timer.

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