Systems and methods for pain mitigation via non-invasive electrical stimulation

Abstract

An apparatus for transdermal electrical stimulation includes one or more first electrodes, one or more second electrodes spaced apart from the one or more first electrodes, and an electrical stimulation unit configured to generate a programmable pulse sequence during one period of electrical stimulation. The programmable pulse sequence includes a first cathodic pulse followed by a second cathodic pulse. The first cathodic pulse and the second cathodic pulse are delivered via the one or more first electrodes by imposing, respectively, a first anodic pulse and a second anodic pulse at the one or more second electrodes.

Description

SYSTEMS AND METHODS FOR PAIN MITIGATION VIA NON-INVASIVEELECTRICAL STIMULATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 567,136, filed March 19, 2024, which is incorporated herein by reference in its entirety.FIELD

[0001] The present disclosure concerns systems and methods for pain mitigation via non-invasive electrical stimulation.BACKGROUND

[0002] Noninvasive electrical stimulation for pain relief has been explored as an alternative or complement to pharmacological therapies due to its potential to provide safer, quicker, and more cost-effective pain management. Techniques such as Transcutaneous Electrical Nerve Stimulation (TENS) have been developed to mitigate chronic pain in conditions like Diabetic Peripheral Neuropathy (DPN), irritable bowel syndrome, rheumatoid arthritis, and postoperative pain.However, existing systems face limitations in portability, comfort, and efficacy. Portable devices often lack secure placement during daily activities or fail to accommodate patients with severe nerve damage or amputations. Moreover, conventional stimulation waveforms inadequately excite Pacinian corpuscles (PCs) — key mechanoreceptors responsible for effective pain relief — leading to reduced efficacy, brief post-stimulation relief, and potential discomfort. These drawbacks hinder patient compliance and therapy outcomes. Thus, there is room for improvement in developing portable, versatile, and efficacious systems for noninvasive pain relief.SUMMARY

[0003] Described herein are systems and methods for pain mitigation via non-invasive electrical stimulation.

[0004] Certain examples of the disclosure concern an apparatus for transdermal electrical stimulation. The apparatus includes one or more first electrodes, one or more second electrodes spaced apart from the one or more first electrodes, and an electrical stimulation unit configured to generate a programmable pulse sequence during one period of electrical stimulation. The programmable pulse sequence includes a first cathodic pulse followed by a second cathodic pulse. The first cathodic pulse and the second cathodic pulse are delivered via the one or more firstelectrodes by imposing, respectively, a first anodic pulse and a second anodic pulse at the one or more second electrodes.

[0005] Certain examples of the disclosure also concern a system for transdermal electrical stimulation. The system includes an electrode array, an attachment mechanism configured to secure the electrode array over a body portion of a user, and an electrical stimulation unit configured to deliver electrical pulses to the electrode array according to a programmable pulse sequence during one period of electrical stimulation. The programmable pulse sequence includes at least two consecutive cathodic pulses delivered via at least one electrode in the electrode array. Pulse amplitudes for the at least two consecutive cathodic pulses are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

[0006] Certain examples of the disclosure further concern a method for transdermal electrical stimulation. The method includes delivering, during one period of electrical stimulation, a plurality of electrical pulses to an electrode array attached to a body portion of a user according to a predefined pulse sequence. Delivering the plurality of electrical pulses includes delivering two or more consecutive cathodic pulses via at least one electrode in the electrode array. Pulse amplitudes of the at least two consecutive cathodic pulses are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

[0007] The technologies described herein can be applied for mitigating a variety of pains, including those associated with chronic conditions, postoperative recovery, and other localized or systemic pain disorders. Additionally, the disclosed technologies can be used to treat certain mental and behavioral health disorders.

[0008] The foregoing and other features and advantages of the disclosed technologies will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1A schematically depicts an example wearable device, hosting an electrode array, worn on a left ear of a user, viewed in front of the ear.

[0010] FIG. IB schematically depicts the wearable device of FIG. 1 A, viewed from behind the ear.

[0011] FIG. 1C schematically depicts the wearable device of FIG. 1 A, viewed from a side of the ear.

[0012] FIG. ID is a perspective view of the wearable device of FIG. 1A, showing two electrodes configured to sit on the cymba concha area when the wearable device is worn on the ear.

[0013] FIG. IE is another perspective view of the wearable device of FIG. 1A, showing two other electrodes configured to sit in the posterior crus of the antihelix area when the wearable device is worn on the ear.

[0014] FIG. IF depicts an electrical stimulation unit worn on an arm of a user, according to one example.

[0015] FIG. 1G schematically depicts an alternative anchoring mechanism for attaching multiple electrodes to an ear of a user, according to one example.

[0016] FIG. 2A depicts an example configuration which places six electrodes on an ear of a user.

[0017] FIG. 2B depicts an example attachment mechanism for securing the six electrodes of FIG. 2A on the ear.

[0018] FIG. 3 schematically depicts an example system for transdermal neural stimulation for pain mitigation.

[0019] FIG. 4 depicts a portion of example waveforms delivered via four electrodes for transdermal neural stimulation.

[0020] FIG. 5 depicts a portion of example waveforms delivered via two electrodes for transdermal neural stimulation.

[0021] FIG. 6A depicts polarity settings of six electrodes when delivering a first cathodic pulse in a first duplex, according to one example.

[0022] FIG. 6B depicts polarity settings of the six electrodes of FIG. 6A when delivering a second cathodic pulse in the first duplex.

[0023] FIG. 6C depicts polarity settings of the six electrodes of FIG. 6A when delivering a first cathodic pulse in a second duplex.

[0024] FIG. 6D depicts polarity settings of the six electrodes of FIG. 6A when delivering a second cathodic pulse in the second duplex.

[0025] FIG. 6E depicts polarity settings of the six electrodes of FIG. 6A when delivering a first cathodic pulse in a third duplex.

[0026] FIG. 6F depicts polarity settings of the six electrodes of FIG. 6A when delivering a second cathodic pulse in the third duplex.

[0027] FIG. 7 schematically depicts an example electrode configuration for transdermal neural stimulation on a flat skin surface of a user.

[0028] FIG. 8 is a block diagram of an example computing system in which described technologies can be implemented.DETAILED DESCRIPTIONOverview of Transdermal Neural Stimulation for Pain Mitigation

[0029] The technologies disclosed herein focus on non-invasive electrical stimulation through the skin to address various physical, mental, and behavioral health conditions. Specifically, the disclosed systems and methods can achieve targeted electrical excitation of nerve fibers and mechanoreceptors to mitigate pain associated with conditions such as Diabetic Peripheral Neuropathy (DPN), a common complication of type 2 diabetes mellitus. Pain caused by DPN affects over 9 million individuals in the United States and 150 million globally, representing a significant challenge for which no universally accepted first-line treatment exists.

[0030] Non-invasive electrical stimulation is often preferred over pharmacological therapy or used as an adjunct due to its potential to be faster, safer, more effective, and more cost-efficient. Beyond DPN, these methods may be applied to other pain conditions, including pain related to irritable bowel syndrome, rheumatoid arthritis, dental procedures, postoperative recovery, post-stroke pain, dysmenorrhea, labor, and more. Moreover, such stimulation can extend to mental and behavioral health management, including stress reduction, anxiety relief, and the treatment of conditions like substance use disorders, eating disorders, and sleep disturbances. It may also aid in blood pressure control, glucose management, lipid regulation, and Body Mass Index (BMI) control in patients with type 2 diabetes, and can be applied to neurological and developmental conditions such as Attention-Deficit / Hyperactivity Disorder (ADHD), autism, and dyslexia, or even improve outcomes in cardiovascular conditions like atrial fibrillation.

[0031] Chronic pain mitigation through the stimulation of non-nociceptive fibers has been explored previously, specifically by targeting large-diameter cutaneous fibers (Ap fibers) in areas such as the lower leg. However, current Transcutaneous Electrical Nerve Stimulation (TENS) and similar systems face significant challenges, particularly in terms of portability and patient compliance. Many existing systems lack portability, interfering with daily activities and reducing patient acceptability. For example, portable devices that can be worn on the lower leg often shift in position during movement, such as walking, and may cause limb compression, which is especially undesirable for diabetic patients, particularly those with peripheral arterial disease or those requiring amputation. Additionally, these existing systems are often limited in their ability to be applied to other body regions, which may be necessary, for example, when sensory nerves in the leg are severely damaged.

[0032] Another significant limitation of conventional systems is related to the applied stimulation waveforms and the fibers targeted. Evidence suggests that mechanoreceptors known as Pacinian corpuscles (PCs), which are responsible for vibration sensation, play a predominant role in painreduction, contributing to approximately 90% of the observed effect. PCs have a resonant frequency range of 200 Hz to 300 Hz, yet waveforms applied by conventional systems typically operate at lower frequencies (typically tens of Hz), failing to adequately stimulate PCs. Conventional electrical stimulation systems may also produce unwanted sensations at electrode sites (thus causing discomfort for the user) given localized electrodes, provide only brief periods of temporary relief, and often lose effectiveness over time. Furthermore, PCs are among the first mechanoreceptors to deteriorate in distal regions of the body, such as the hands and feet, due to diabetes, reducing the efficacy of leg-based stimulation devices for DPN-related pain relief.

[0033] In sum, existing systems for non-invasive electrical stimulation to treat painful DPN face several limitations, including portability, applicability, and stimulation efficacy, which hinder patient compliance and overall therapy outcomes. Many of these challenges can be overcome by the technologies described herein, as described more fully below.Example Transdermal Electrical Stimulation System

[0034] FIG. 3 shows an example transdermal electrical stimulation system 300 for pain mitigation.

[0035] The transdermal electrical stimulation system 300 includes an electrode array 100 configured to be attached to a body portion of a user 310, a portable or wearable electrical stimulation unit 107, and a mobile computing device 302.

[0036] The electrode array 100 includes a plurality of electrodes. In the depicted example, the electrode array 100 is attached to an ear 101 of the user 310. The electrical stimulation unit 107 is worn on an arm of the user 310. The mobile computing device 302 can be a smartphone, a tablet, a laptop, or the like.

[0037] In other examples, the electrode array 100 can be attached to other portions of the user’s body, such as lower back, neck, chest, legs, arms, etc.

[0038] In other examples, the electrical stimulation unit 107 may be worn on or attached to other parts of the body or accessories, such as the waist, neck, hat, shoulder, or clothing, depending on user preferences and comfort.

[0039] In some examples, the electrical stimulation unit 107 includes a pulse generator configured to generate electrical pulses in various waveforms according to programmable or predefined stimulation patterns. The electrical pulses can be delivered to the body portion of the user via the electrode array 100. In some examples, a routing cable 106 can be used to establish electrical connections between the electrode array 100 and the electrical stimulation unit 107.

[0040] In some examples, the waveforms generated by the electrical stimulation unit 107 can be programmed by the mobile computing device 302. In some examples, the electrical stimulationunit 107 can also be configured to measure stimulation information, such as impedance of the electrodes in the electrode array 100.

[0041] In some examples, the mobile computing device 302 can be replaced with a stationary computer or another laptop not carried by the user, such as a computer in a physician’s office, which can be used by the physician to program and / or interrogate the electrical stimulation unit 107.

[0042] In some examples, the mobile computing device 302 can establish and maintain bidirectional communication 301 with the electrical stimulation unit 107. In some examples, the mobile computing device 302 can wireless communicate with the electrical stimulation unit 107, for example, via low-energy Bluetooth® or other known wireless communication protocols.

[0043] In some examples, the electrical stimulation unit 107 can be battery-operated. In some examples, the electrical stimulation unit 107 features an indicator 304 (e.g., an LED or the like), which can display the battery status.

[0044] In some examples, the electrical stimulation unit 107 can include a connector 305 for recharging if it is powered by rechargeable batteries. In some examples, the electrical stimulation unit 107 may support wireless charging functionality. The indicator 304 can be configured to provide various indications, such as charging progress, current battery status, end-of-charge notifications, etc.

[0045] In some examples, the mobile computing device 302 can run a pre-installed application (App) 303 that allows the user 310 (and / or the physician) to program and control stimulation parameters used by the electrical stimulation unit 107. For example, some of the stimulation parameters can be configured to target the auricular branches of the vagus nerve (ABVN) and mechanoreceptors. In some examples, these parameters can be configured and programmed during an initial fitting session conducted with the patient at the physician’s office. After the fitting session, the patient can independently operate and control the electrical stimulation unit 107 using the App 303.

[0046] In some examples, the App 303 allows the user to perform a variety of tasks, such as calibrating the electrode array after application, creating and managing therapy schedules (e.g., daily or nightly sessions), turning ON / OFF the stimulation, or adjusting stimulation intensity to suit their needs. In some examples, the user can use the App 303 to interrogate the electrical stimulation unit 107 to obtain statistics and other status information. For instance, the App 303 can allow the user to monitor therapy usage statistics, check battery levels, and receive alerts for electrode misplacement or when a replacement is needed, ensuring a seamless and personalized therapy experience.

[0047] The transdermal electrical stimulation system 300 and any of the other systems described herein can be implemented in conjunction with any of the hardware components described herein, such as the computing systems described below (e.g., processing units, memory, and the like). In any of the examples herein, the software applications, the programmable pulse sequences, the stimulation parameters, electrode configurations, and the like can be stored in one or more computer-readable storage media or computer-readable storage devices. The technologies described herein can be generic to the specifics of operating systems or hardware and can be applied in any variety of environments to take advantage of the described features.Example Electrode Configuration for Auricular Stimulation

[0048] FIGS. 1 A-1E depicts an example electrode array 100 which can be worn on a left ear 101 of a user. It should be understood that the electrode array 100 can also be worn on the right ear, or two electrode arrays 100 may be worn bilaterally on both ears.

[0049] The electrode array 100 can be secured to a body portion (e.g., the ear 101) of a user (e.g., the user 310) via an attachment mechanism. In some examples, the attachment mechanism can include a mechanical structure configured to be worn by the user, such as a frame 120 which can be attached to the ear 101. Thus, the electrode array 100 and the attachment mechanism can constitute a wearable device.

[0050] As shown, the frame 120 can be a unitary piece including an anterior anchor 102 which can be positioned in the cavum concha area of the ear, and a posterior flap 103 configured to be positioned behind the ear 101. The frame 120 can also have a support member 104 adjacent to the anterior anchor 102. The support member 104 can have a T shape and project angularly upward relative to the anterior anchor 102. When the frame 120 is attached to the ear 101, the support member 104 can be situated in the cymba concha area, which is richly innervated by the nervus intermedins, the auricular branch of the vagus nerve (ABVN), and the greater auricular nerve, all of which relay information from subcutaneous mechanoreceptors such as PCs. The size and / or shape of the frame 120 can be configured to fit the geometry of the ear 101. In some examples, the frame 120 can be configured to be bendable to ensure snuggly fitting with the ear 101. In still other examples, the frame 120 can comprise multiple separable pieces (e.g., the anterior anchor 102 and the posterior flap 103 may be constructed as two separate pieces).

[0051] The electrode array 100 can include a plurality of electrodes positioned at specific locations of the frame 120. For example, the support member 104 can host a group of two electrodes, 105. a and 105.b. The posterior flap 103 can contain a group of two additional electrodes, 105.C and 105. d, which are configured to adhere to the posterior crus of the antihelix area of the ear 101.Thus, in the example depicted in FIGS. 1 A-1E, the electrode array 100 has four electrodes divided into two groups that are respectively distributed over anterior and posterior sides of the ear 101.

[0052] As shown in FIG. IF, all electrodes (collectively, 105) in the electrode array 100 can be connected, e.g., via a routing cable 106, to the electrical stimulation unit 107 which can be worn on another body port (e.g., arm) of the user.

[0053] In some examples, the electrode array 100 can be attached to the user’s body portion (e.g., ear 101) via a different attachment mechanism, such as using one or more adhesive members (e.g., tapes or the like). Tn some examples, each adhesive member can have a dry polymeric hydrogel layer disposed on a hypoallergenic, non-conductive substrate.

[0054] As an example, FIG. 1G shows another electrode array 100 having a group of two electrodes 105. a, 105.b secured to the cymba concha area by one adhesive member 108, and a group of two electrodes 105.C, 105. d adhered to the posterior crus of the antihelix area by another adhesive member 110. Additionally, the electrode array 100 can have one or more electrodes situated at other locations of the ear. For example, one adhesive member 112 can adhere to the preauricular area and host a group of at least one electrode 109, targeting branches of the trigeminal nerve. In some examples, the routing cable 106 can incorporate strain relief areas 111 (e.g., a loose cable loop, or the like), which may also adhere to the skin using an adhesive member to enhance stability.

[0055] As another example, FIG. 2A depicts an electrode array 100 having six electrodes, 105. a through 105. f, which are arranged in a different configuration. In this example, the positions of electrodes 105. a through 105. d remain substantially identical to those shown in FIGS. 1 A-1E, and FIG. 1G, while a group of two other electrodes, 105.e and 105.f are added in the cavum concha area. Electrodes 105. a through 105. f can be positioned near acupressure points COio, COis, AT4, and TF4. These locations correspond to regions of the ear 101 that are rich in auricular branches of the vagus nerve (ABVN), which can play important roles in Transdermal Auricular Vagus Nerve Stimulation (taVNS). The arrangement of electrodes (collectively, 105) shown in FIG. 2A also allows for the recruitment of mechanoreceptors in the external ear canal, utilizing guarded cathode stimulation configurations described below.

[0056] In some examples, the electrode array 100 of FIG. 2A can be integrated onto the frame 120 described above. For example, like the examples shown in FIGS. 1A-1E, electrodes 105. a, 105.b can be hosted by the support member 104, while electrodes 105. c, 105. d can be hosted by the posterior flap 103. The two additional electrodes 105. e, 105. f can be hosted by the anterior anchor 102.

[0057] In some examples, the support member 104 and the anterior anchor 102 can be combined to form a single piece 200, as shown in FIG. 2B. This single piece 200 can be shaped to resemble an in-ear monitor worn by musicians during live performances to hear their vocals and stage music. Thus, all four electrodes, 105. a, 105.b, 105. e, and 105. f, can be hosted on this single piece 200, while the other two electrodes, 105. c and 105.d, are hosted by the posterior flap 103.

[0058] In other examples, any or all of the electrodes 105. a through 105. f depicted in FIG. 2A can be attached to the ear by other means, such as using adhesive members described above.

[0059] In some examples, the electrode array 100 can include only two electrodes, e.g., one electrode selected from the group of electrodes 105. a and 105.b, and another electrode selected from the group of electrodes of 105. c and 105. d. In some examples, electrode array 100 can include more than three electrode groups, e.g., by including another group of electrodes located at a location spaced apart from the electrodes depicted in FIGS. 2A-2B.

[0060] In some examples, any of the electrode groups described above can have only one electrode or more than two electrodes. For example, the group of electrodes in the cymba concha area can have one, two, three, four, or more electrodes.Example Electrodes

[0061] In various examples disclosed herein, electrodes in the electrode array 100 (e.g., electrodes 105. a through 105. f) can be configured to be disposable after a limited number of reuses. In some examples, these electrodes may be constructed using non-polarizable conductive-ink traces applied to a hypoallergenic, non-conductive substrate with self-adhesive dry polymeric hydrogel layers. The use of hydrogels not only ensures the electrodes remain in place but also disperses current evenly to minimize the risk of skin irritation.

[0062] In some examples, the electrical stimulation unit 107 can monitor the electrical impedance of the electrodes and indicate when electrode replacement is necessary.

[0063] In various examples disclosed herein, electrodes in the electrode array 100 may also be fabricated from materials such as carbon-rubber, carbon-polymer, or graphene. In some configurations, only a subset of electrodes in the electrode array 100 may be disposable and made of these materials. Other non-disposable electrodes may utilize biocompatible metals such as 316L stainless steel, platinum-iridium (Pt-Ir), titanium-iridium (Ti-Ir), or other suitable materials.

[0064] In some examples, each electrode can have a diameter of about 5.0 mm. In other examples, the electrodes can have a larger or smaller diameter. In some examples, the electrodes can have a non-circular shape.

[0065] In some examples, a center-to-center distance between two adjacent electrodes in the same group or in the same ear area (e.g., center-to-center distances between electrodes 105. a and 105. b,or between 105. c and 105. d in FIGS. 1 A-1E and FIG. 2A-2B, or between 105.e and 105.f in FIGS. 2A-2B) can be between 8.0 mm and 12.0 mm, e.g., about 10.0 mm. In other examples, two adjacent electrodes in the same group can have a larger or smaller center-to-center distance.

[0066] Generally, the center-to-center distance between two electrodes that are in different groups or different ear arears are larger than the center-to-center distance between two adjacent electrodes in the same group.Example Overview of Facilitatory Effect

[0067] The technologies disclosed herein involves electrical stimulation of a target area of the body portion using specific stimulation patterns which can create a facilitatory effect that enhances the excitability of the targeted mechanoreceptors and nerve fibers. Specifically, the electrical stimulation can be periodic (e.g., generating a periodic stimulation waveform), and during one period of electrical stimulation, a programmable pulse sequence can be generated that includes two consecutive cathodic pulses (also referred to as stimulation pulses). Each of the two consecutive cathodic pulses can have an amplitude that is lower than the excitation threshold required to activate subcutaneous mechanoreceptors and nerve fibers when using a single cathodic pulse. This approach leverages a facilitatory effect in which the first pulse induces a transient increase in neuronal excitability, effectively lowering the excitation threshold of the targeted mechanoreceptors and nerve fibers.

[0068] For example, if the baseline excitation threshold (i.e., the excitation threshold required to generate an action potential in the absence of prior stimulation pulse) is denoted as TH, the first cathodic pulse can modulate the local membrane potential and ion channel dynamics, reducing the threshold to TH x p, where p is a value between 0 and 1. If a second cathodic pulse is delivered within a short temporal window following the first cathodic pulse, its amplitude can be set above TH x p but still below TH, thereby successfully eliciting an action potential and activating the targeted mechanoreceptors and nerve fibers. This facilitatory effect may arise due to mechanisms such as residual depolarization, the priming of voltage-gated sodium channels, and / or changes in the local extracellular ionic environment that transiently enhance neuronal responsiveness.

[0069] The baseline excitation threshold of mechanoreceptors and nerve fibers can be measured using various physiological metrics that reflect neural activation. One method involves monitoring heart rate and / or heart rate variability (HRV), as the activation of afferent fibers, particularly those associated with the auricular branch of the vagus nerve (ABVN), can modulate autonomic function. Other approaches include recording evoked potentials in response to stimulation, assessing skin conductance changes, measuring transient changes in blood pressure, utilizing electromyography (EMG) to detect muscle reflexes linked to mechanoreceptor activation, and so on. In someexamples, the baseline excitation threshold of mechanoreceptors and nerve fibers can be measured during the initial fitting session conducted with the patient at the physician’s office, and the stimulation parameters can be programmed accordingly, e.g., the pulse amplitudes can be programmed to below the baseline excitation threshold.Example Pulse Sequences for Electrode Array with Four Electrodes

[0070] FIG. 4 shows an example stimulation protocol of electrical stimulation waveform for a four- electrode configuration, such as the electrodes 105.a-105.d shown in FIGS. 1A-1E. The electrical stimulation waveform can be generated by one or more pulse generators within the electrical stimulation unit 107.

[0071] In FIG. 4, the stimulation protocol involves two pairs of stimulation sequences, referred to as duplets 400.1 and 400.2, each of which can be delivered via a corresponding pair of adjacent electrodes (e.g., two electrodes in the same group or in the same ear area). The duplets 400.1 and400.2 can have a predefined temporal pattern and repeated at a predefined stimulation frequency. The stimulation frequency defines a corresponding period 401 of the electrical stimulation. In some examples, the stimulation frequency is programmed to be above 100 Hz (e.g., between 200 Hz and 300 Hz) to stimulate PCs.

[0072] As shown, the first duplet 400.1 can be applied via a first group of electrodes (e.g., electrodes 105. a and 105.b), while the second duplet 400.2 can be applied via a second group of electrodes (e.g., electrodes 105. c and 105. d). Each duplet includes two consecutive cathodic pulses (with a negative polarity). For example, the first duplet 400.1 includes a first cathodic pulse 402. 1 delivered via one electrode (e.g., 105. a) followed by a second cathodic pulse 402.2 delivered via an adjacent electrode (e.g., 105.b). Likewise, the second duplet 400.2 includes a third cathodic pulse402.3 delivered via one electrode (e.g., 105. c) followed by a fourth cathodic pulse 402.4 delivered via an adjacent electrode (e.g., 105. d). In the depicted example, when cathodic pulses 402. 1, 402.2 are delivered via the first group of electrodes, the second group of electrodes act as anodes, concurrently imposing corresponding anodic pulses to maintain charge balance and ensure controlled current flow. Likewise, when cathodic pulses 402.3, 402.4 are delivered via the second group of electrodes, the first group of electrodes act as anodes, concurrently imposing corresponding anodic pulses to maintain charge balance and ensure controlled current flow.

[0073] Each cathodic pulse (402. 1-402.4) delivered to respective electrodes can be a current- controlled stimulation pulse characterized by an amplitude 403 and a pulse width 404. Both the pulse amplitude 403 and pulse width 404 can be programmable (e.g., via the mobile computing device 302).

[0074] In some examples, the pulse amplitude 403 and pulse width 404 for the two consecutive cathodic pulses within each duplet can be the same. In other examples, the two consecutive pulses within each duplet can have different pulse amplitudes and / or pulse width. For example, the pulse amplitude 403 of the first cathodic pulse 402.1 can be the same as that of the second cathodic pulse 402.2, or alternatively, the first cathodic pulse 402.1 can have a smaller or larger amplitude than the second cathodic pulse 402.2.

[0075] To generate the cathodic stimulation amplitude 403, simultaneous current sources can be imposed at the electrodes designated as anodes (with a positive polarity), and the combined currents collected at the corresponding cathode for each cathodic pulse. For instance, when the electrode 105. a functions as the cathode during the cathodic pulse 402.1, electrodes 105. c and 105. d may serve as anodes, supplying current sources to establish the required cathodic stimulation via the electrode 105. a. Similarly, when the electrode 105.b functions as the cathode during the cathodic pulse 402.2, electrodes 105.C and 105.d may still serve as anodes, supplying current sources to establish the required cathodic stimulation via the electrode 105.b. On the other hand, when the electrode 105. c or 105. d functions as the cathode during the cathodic pulse 402.3 or 402.4, electrodes 105. a and 105. b may serve as anodes, supplying current sources to establish the required cathodic stimulation via the electrode 105.c or 105.d.

[0076] An inter-pulse interval 405 separates the two consecutive cathodic pulses within each duplet. The inter-pulse interval 405 measures the time interval between the end of the cathodic pulse 402.1 and the start of the cathodic pulse 402.2 (or between the end of the cathodic pulse 402.3 and the start of the cathodic pulse 402.4). This inter-pulse interval 405 can be a programmable parameter that enables fine-tuning of the facilitatory effect between consecutive cathodic pulses within the same duplet. This facilitatory effect can be conceptualized as a cascading process, where the first cathodic pulse (e.g., 402.1) brings the excitable tissue closer to the depolarization threshold, and the second cathodic pulse (e.g., 402.2) completes the depolarization, thereby eliciting an action potential. This facilitatory mechanism can lower the overall charge required for effective stimulation, enhance recruitment of deeper excitable tissues, and minimize unintended stimulation of cutaneous receptors, thereby reducing undesirable side effects (e.g., twitching) on the skin.

[0077] In some examples, a passive charge balance pulse 406 (also referred to as charge-balance phase) can be delivered via the electrodes after the delivery of two consecutive cathodic pulses in each duplet. The passive charge balance phase can be implemented across all four electrodes (e.g., 105.a-105.d in the example) to reduce or minimize residual charge accumulation, thereby helpingmaintain charge neutrality, which is important for safe and effective long-term stimulation. In some examples, the delivery of passive charge balance pulse 406 can be optional.Example Stimulation Parameters

[0078] In some examples, one or more of the stimulation parameters depicted in FIG. 4 can be programmed, e.g., via secure clinician access within the App 303.

[0079] The following lists exemplary, non-limiting programmable ranges for some of the stimulation parameters:

[0080] Stimulation frequency (the inverse of period 401): 1 to 500 Hz (e.g., adjustable in 1 Hz increments).

[0081] Stimulation amplitude 403: 0.1 mA to 5.0 mA (e.g., adjustable in 0.1 mA increments).

[0082] Stimulation pulse width 404: 10 ps to 1000 ps (e.g., adjustable in 5 ps increments).

[0083] Inter-pulse interval 405: 10 ps to 2000 ps (e.g., adjustable in 10 ps increments).

[0084] The stimulation frequency can be constrained by the combination of stimulation pulse width 404, inter-pulse interval 405, and the minimum duration required for the passive charge balance phase 406.

[0085] Additionally, the product of stimulation pulse width 404 and stimulation amplitude 403 may be limited by the maximum safe charge injection per stimulation pulse, which may depend on the electrode’s surface area and material properties.

[0086] In some examples, any of the above stimulation parameters can be dynamically adjusted during trialing to achieve a targeted physiological response, such as a specific reduction in heart rate (e.g., a 5 bpm decrease) following auricular stimulation. Heart rate modulation can be monitored using commercially available heart rate measurement devices to fine-tune the stimulation settings for optimal therapeutic outcomes.Example Approaches for Reducing Habituation

[0087] To minimize habituation of Pacinian corpuscles (PCs) and nerve fibers to electrical stimulation, various approaches can be employed to introduce variability in stimulation parameters over a therapeutic session, thereby maintaining therapeutic efficacy over extended use.

[0088] In some examples, temporal variations in the stimulation waveform can be introduced to prevent neural adaptation. For instance, the stimulation frequency may be varied in a randomized or pseudo-randomized manner (e.g., within a range of 10 Hz to 400 Hz, or the like). Additionally, and / or alternatively, a fine duty cycle, such as 60 seconds of stimulation ON followed by 30 seconds of OFF, can be applied to further reduce neural accommodation.

[0089] In some examples, habituation can be reduced by dynamically adjusting one or more stimulation parameters in a randomized or pseudo-randomized fashion during therapy delivery.Parameters subject to variation may include stimulation pulse width 404 and inter-pulse interval 405, among others. In some examples, pseudo-randomization can be controlled by defining a center value and a deviation limit for each parameter, with a random number generator producing statistically flat (white noise) distributions within these limits. To ensure sufficient variation, parameter randomness may be constrained such that no correlation exists between fewer than a predefined number (e.g., 16) of consecutive samples, and autocorrelation within a single parameter does not occur in fewer than another predefined number (e.g., 64) of samples.

[0090] In some examples, a gradual ramp-up and / or ramp-down of stimulation intensity can be implemented to enhance patient comfort and mitigate abrupt changes in neural excitation. These ramps can be clinician-programmable and may be configured to be symmetrical (e.g., identical ramp-up and ramp-down), asymmetrical (e.g., ramp-up only or ramp-down only), or disabled entirely. The programmable ramp parameters may include ramp duration which can be between 0.0 to 10.0 seconds (e.g., adjustable in 0.2-second increments), and ramp stimulation amplitude 403 steps which can be between 1 to 8 (e.g., in increments of 1, where 1 represents no ramping). In other examples, different ramp parameters can be programmed.

[0091] In some examples, beyond ramping strategies, clinicians may also define scheduled therapy sessions (coarse duty cycles) to optimize treatment timing and reduce continuous exposure to stimulation, further preventing habituation while maintaining therapeutic effectiveness.Example Pulse Sequences for Electrode Array with Two Electrodes

[0092] FIG. 5 shows an example stimulation protocol of electrical stimulation waveform using only two electrodes, for example, with one electrode selected from the group of electrodes 105. a and 105.b, and the other selected from the group of electrodes 105. c and 105. d. The electrical stimulation waveform can be generated by one or more pulse generators within the electrical stimulation unit 107.

[0093] As shown, this configuration employs two consecutive cathodic pulses in one selected electrode, e.g., a first cathodic pulse 500 (also referred to as pre-pulse) followed by a second cathodic pulse 501 (also referred to as primary stimulation pulse), to create a facilitatory effect. The cathodic pulses 500, 501 can be delivered to the selected electrode (e.g., electrode 105. a or 105.b) by concurrently imposing corresponding anodic pulses at the other electrode (e.g., electrode 105. c or 105. d). As described above, the first pulse 500 can reduce the excitation threshold of the targeted mechanoreceptors and nerve fibers, thereby enhancing their excitability or responsiveness to the subsequent second pulse 501. The time interval between the first cathodic pulse 500 and the second cathodic pulse 501, referred to as the inter-pulse interval 505, can be adjusted to optimize the facilitatory effect by allowing sufficient temporal summation of membrane depolarization. Theinter-pulse interval 505 may be zero, implying the stimulation amplitude 403 changes between the first cathodic pulse and second cathodic pulse without returning to zero in between.

[0094] Optionally, to maintain charge balance, charge compensation can be achieved through an active charge-balance phase 502 and / or a passive charge-balance phase 503, utilizing the same electrode pair.

[0095] Stimulation can be delivered at a defined frequency, which corresponds to a period 504 of the electrical stimulation, to maintain therapeutic effectiveness.

[0096] The total charge injected by the first cathodic pulse 500 can be equal to or different from (e.g., lower than) the charge delivered by the second cathodic pulse 501, ensuring controlled excitation while mitigating excessive charge accumulation.

[0097] As described above, one or more stimulation parameters (e.g., stimulation frequency, pulse amplitudes and pulse widths for the two consecutive cathodic pulses, the inter-pulse interval, stimulation ON / OFF schedule, etc.) can be perturbed and / or adjusted to reduce habituation effect.Example Pulse Sequences for Electrode Array with Six Electrodes

[0098] FIGS. 6A-6F illustrate polarity settings (“+” indicates anode andindicates cathode) of an electrode array with six electrodes (e.g., the electrode array 100 depicted in FIGS. 2A-2B) when generating pulse sequences during one period of electrical stimulation.

[0099] In this example, the pulse sequences within the stimulation period includes three duplets, referred to 600.1, 600.2, and 600.3, respectively. Each duplet includes two consecutive cathodic pulses delivered via two adjacent electrodes (e.g., similar to the duplets 400.1 and 400.2 of FIG. 4). In the depicted example, the first duplet 600.1 can be delivered via a first group of two electrodes 105. a, 105.b (FIGS. 6A-6B), the second duplet 600.2 can be delivered via a second group of two electrodes 105. e, 105. f (FIGS. 6C-6D), and the third duplet 600.3 can be delivered via a third group of two electrodes 105.C, 105. d (FIGS. 6E-6F).

[0100] For instance, for the first cathodic pulse in the first duplet, the electrode 105.b can act as a cathode, while electrodes 105. c, 105.d, 105. e, and 105. f serve as the anodes (FIG. 6A). This is a guarded cathode configuration, as the four anodal electrodes 105. c, 105.d, 105. e, and 105. f are positioned on opposite sides of the cathodal electrode 105.b. In this guarded configuration, current sources are applied to the anodes 105. c, 105. d, 105.e, and 105. f, and the resulting currents are collected at cathode 105. b.

[0101] The second cathodal pulse of the first duplet 600.1 follows the configuration with the same anodes (105. c, 105.d, 105. e, and 105. f), but electrode 105. a becomes the cathode instead (FIG. 6B). This second cathodal pulse also operates in a guarded cathode configuration as the anodes are positioned on both sides of the cathode. As previously described, a facilitatory effect occursbetween the two stimulation pulses of the first duplex 600.1 , enhancing the excitability of subcutaneous mechanoreceptors and nerve fibers in the area near acupressure point COw of the ear. In some examples, the order of cathodes can be reversed, e.g., electrode 105. a can serve as the first cathode, with electrode 105.b can act as the second cathode in the first duplet 600.1.

[0102] In the first cathodal pulse of the second duplet 600.2, electrode 105. e can act as the cathode, and electrodes 105. a, 105. b, 105.C, and 105. d can serve as the anodes (FIG. 6C). The second cathodal pulse for the second duplet 600.2 can have the same anodes (105.a, 105.b, 105. c, and 105. d) but with electrode 105. f as the cathode (FIG. 6D). Similarly, a facilitatory effect occurs between the two stimulation pulses of the second duplex 600.2, enhancing the excitability of subcutaneous mechanoreceptors and nerve fibers in the area near acupressure points COis and AT4 of the ear. Again, the order of cathodes can be reversed, e.g., with electrode 105. f being the first cathode and electrode 105.e serving as the second cathode in the second duplet 600.2.

[0103] Then, in the first cathodal pulse of the third duplet 600.3, electrode 105. c can act the cathode, with electrodes 105. a, 105.b, 105.e, and 105. f acting as the anodes (FIG. 6E). The second cathodal pulse in the third duplet 600.3 can have the same anodes (105. a, 105.b, 105. e, and 105. f) but with electrode 105. d as the cathode (FIG. 6F). Similarly, a facilitatory effect occurs between the two cathodal pulses of the third duplex 600.3, enhancing the excitability of subcutaneous mechanoreceptors and nerve fibers in the area near acupressure point TF4 of the ear. Likewise, the order can be reversed, with electrode 105. d serving as the first cathode and electrode 105. c as the second cathode in third duplet 600.3.

[0104] Optionally, a passive balance operation may occur between all six electrodes 105.a-105.f after the second cathodal pulse of third duplet 600.3 and before the repetition of the first cathodal pulse of first duplet 600.1 in the next stimulation period.

[0105] Similarly, stimulation parameters such as pulse duration, amplitude, and stimulation frequency may be dynamically adjusted to minimize the habituation effect, as described above.

[0106] Although FIGS. 6A-6F show a specific sequence of electrical stimulation during one stimulation period, it should be understood that the sequence of the duplets can be varied. For example, instead of following the duplet sequence 600.1-600.2-600.3, the three duplets can be arranged in a different sequence such as 600.2-600.1-660.3, or 600.3-600.2-600.1, or the like. Example Alternative Electrode Configurations

[0107] As another embodiment of the electrode array 100, FIG. 7 depicts a patch-type electrode array which is configured to adhere to the lower back, neck, or other conformable areas of a subject, e.g., using a dry polymeric hydrogel layer 700.

[0108] In the depicted example, the electrode configuration includes two inner electrodes, 105. a and 105.b, and two outer electrodes 105. c and 105. d. The two inner electrodes 105. a and 105. b are arranged in a cross-coupled pattern. Specifically, each inner electrode can be split into two half electrodes that are spaced apart from one another but are nonetheless connected by a conductive wire. The split four half electrodes can be arranged in four different quadrants, with two half electrodes of 105. a located in two diagonally opposite quadrants and the two half electrodes of 105.b located in two other diagonally opposite quadrants. The two outer electrodes 105. c and 105. d are configured to encircle the inner electrodes 105. a, 105.b, nearly completing a full circumference (e.g., with two small gaps at the top and bottom regions). In other words, the two outer electrodes 105. c and 105. d are positioned around the two inner electrodes 105. a and 105.b. This configuration can facilitate deeper penetration of the electrical stimulation field, enhancing recruitment of Pacinian corpuscles (PCs) and other nerve fibers.

[0109] The electrical traces that connect to the electrodes 105. a, 105.b, 105. c, and 105.d can be bundled into a flat cable 106, which terminates in a header 701. The header 701 can be connected to an electrical stimulation unit (e.g., 107).

[0110] In an alternative version of this electrode array, suitable for other conformable body areas, the inner electrodes 105. a and 105.b can be combined into a single inner electrode. In some examples, the outer electrodes 105. c and 105. d can form a unified outer electrode that fully encloses the inner electrode. This two-electrode configuration allows for the application of the stimulation waveform shown in FIG. 5 for targeting PCs and / or other nerve fibers.

[0111] The stimulation parameters used in this electrode configuration can be adaptable based on the location of the electrode array 100. These parameters can be fine-tuned during trials, e.g., by observing the initiation of muscle recruitment in the area surrounding the electrode array 100.

[0112] Similarly, stimulation parameters such as pulse duration, amplitude, and stimulation frequency may be dynamically adjusted to minimize the habituation effect, as described above. Example Computing Systems

[0113] FIG. 8 depicts an example of a suitable computing system 800 in which the described innovations can be implemented. For example, the computing system 800 can be implemented as a mobile computing device 302 of FIG.3, and / or a computer used by a physician to program and / or interrogate the stimulation unit 107 disclosed herein. The computing system 800 is not intended to suggest any limitation as to scope of use or functionality of the present disclosure, as the innovations can be implemented in diverse computing systems.

[0114] With reference to FIG. 8, the computing system 800 includes one or more processing units 810, 815 and memory 820, 825. In FIG. 8, this basic configuration 830 is included within a dashedline. The processing units 810, 815 execute computer-executable instructions, such as for implementing the features described in the examples herein. A processing unit can be a general- purpose central processing unit (CPU), processor in an application-specific integrated circuit (ASIC), or any other type of processor. In a multi-processing system, multiple processing units execute computer-executable instructions to increase processing power. For example, FIG. 8 shows a central processing unit 810 as well as a graphics processing unit or co-processing unit 815. The tangible memory 820, 825 can be volatile memory (e.g., registers, cache, RAM), non-volatile memory (e.g., ROM, EEPROM, flash memory, etc.), or some combination of the two, accessible by the processing unit(s) 810, 815. The memory 820, 825 stores software 880 implementing one or more innovations described herein, in the form of computer-executable instructions suitable for execution by the processing unit(s) 810, 815.

[0115] A computing system 800 can have additional features. For example, the computing system 800 includes storage 840, one or more input devices 850, one or more output devices 860, and one or more communication connections 870, including input devices, output devices, and communication connections for interacting with a user. An interconnection mechanism (not shown) such as a bus, controller, or network interconnects the components of the computing system 800. Typically, operating system software (not shown) provides an operating environment for other software executing in the computing system 800, and coordinates activities of the components of the computing system 800.

[0116] The tangible storage 840 can be removable or non-removable, and includes magnetic disks, magnetic tapes or cassettes, CD-ROMs, DVDs, or any other medium which can be used to store information in a non-transitory way and which can be accessed within the computing system 800. The storage 840 stores instructions for the software implementing one or more innovations described herein.

[0117] The input device(s) 850 can be an input device such as a keyboard, mouse, pen, or trackball, a voice input device, a scanning device, touch device (e.g., touchpad, display, or the like) or another device that provides input to the computing system 800. The output device(s) 860 can be a display, printer, speaker, CD-writer, or another device that provides output from the computing system 800.

[0118] The communication connection(s) 870 enable communication over a communication medium to another computing entity. The communication medium conveys information such as computer-executable instructions, audio or video input or output, or other data in a modulated data signal. A modulated data signal is a signal that has one or more of its characteristics set or changedin such a manner as to encode information in the signal. By way of example, and not limitation, communication media can use an electrical, optical, RF, or other carrier.

[0119] The innovations can be described in the context of computer-executable instructions, such as those included in program modules, being executed in a computing system on a target real or virtual processor (e.g., which is ultimately executed on one or more hardware processors).Generally, program modules or components include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The functionality of the program modules can be combined or split between program modules as desired in various examples. Computer-executable instructions for program modules can be executed within a local or distributed computing system.

[0120] For the sake of presentation, the detailed description uses terms like “determine” and “use” to describe computer operations in a computing system. These terms are high-level descriptions for operations performed by a computer and should not be confused with acts performed by a human being. The actual computer operations corresponding to these terms vary depending on implementation.Example Computer-Readable Media

[0121] Any of the computer-readable media herein can be non-transitory (e.g., volatile memory such as DRAM or SRAM, nonvolatile memory such as magnetic storage, can be implemented by storing in one or more computer-readable media (e.g., computer-readable storage media or other tangible media). Any of the things (e.g., data created and used during implementation) described as stored can be stored in one or more computer-readable media (e.g., computer-readable storage media or other tangible media). Computer-readable media can be limited to implementations not consisting of a signal.

[0122] Any of the methods described herein can be implemented by computer-executable instructions in (e.g., stored on, encoded on, or the like) one or more computer-readable media (e.g., computer-readable storage media or other tangible media) or one or more computer-readable storage devices (e.g., memory, magnetic storage, optical storage, or the like). Such instructions can cause a computing device to perform the method. The technologies described herein can be implemented in a variety of programming languages.General Considerations

[0123] For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed examples,alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed examples require that any one or more specific advantages be present or problems be solved. The technologies from any example can be combined with the technologies described in any one or more of the other examples. In view of the many possible examples to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated examples are only preferred examples and should not be taken as limiting the scope of the disclosed technology.

[0124] Although the operations of some of the disclosed examples are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods. Additionally, the description sometimes uses terms like “provide” or “achieve” to describe the disclosed methods. These terms are high-level abstractions of the actual operations that are performed. The actual operations that correspond to these terms may vary depending on the particular implementation and are readily discernible by one of ordinary skill in the art. Any theories of operation are to facilitate explanation, but the disclosed systems, methods, and apparatus are not limited to such theories of operation.

[0125] As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the terms “coupled” and “connected” generally mean electrically, electromagnetically, and / or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language.

[0126] Directions and other relative references (e.g., inner, outer, upper, lower, etc.) may be used to facilitate discussion of the drawings and principles herein, but are not intended to be limiting. For example, certain terms may be used such as “inside,” “outside,” “interior,” “exterior,” and the like. Such terms are used, where applicable, to provide some clarity of description when dealing with relative relationships, particularly with respect to the illustrated examples. Such terms are not, however, intended to imply absolute relationships, positions, and / or orientations. For example, with respect to an object, an “upper” part can become a “lower” part simply by turning the object over. Nevertheless, it is still the same part and the object remains the same.

[0127] As used herein, “and / or” means “and” or “or,” as well as “and” and “or.”Example Clauses

[0128] Any of the following example clauses can be implemented.

[0129] Clause 1. An apparatus for transdermal electrical stimulation, the apparatus comprising: one or more first electrodes; one or more second electrodes spaced apart from the one or more first electrodes; and an electrical stimulation unit configured to generate a programmable pulse sequence during one period of electrical stimulation, wherein the programmable pulse sequence comprises a first cathodic pulse followed by a second cathodic pulse, wherein the first cathodic pulse and the second cathodic pulse are delivered via the one or more first electrodes by imposing, respectively, a first anodic pulse and a second anodic pulse at the one or more second electrodes.

[0130] Clause 2. The apparatus of clause 1 , wherein an inter-pulse interval between the first cathodic pulse and the second cathodic pulse is programmable between 0 pis and 2000 ps.

[0131] Clause 3. The apparatus of any one of clauses 1-2, wherein a pulse width of the first cathodic pulse and the second cathodic pulse is programmable between 10 ps and 1000 ps.

[0132] Clause 4. The apparatus of any one of clauses 1-3, wherein pulse amplitudes for both the first cathodic pulse and the second cathodic pulse are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

[0133] Clause 5. The apparatus of clause 4, wherein the pulse amplitudes for both the first cathodic pulse and the second cathodic pulse are programmable between 0. 1 mA and 5.0 mA.

[0134] Clause 6. The apparatus of any one of clauses 4-5, wherein the pulse amplitude for the first cathodic pulse is equal to or lower than the pulse amplitude for the second cathodic pulse.

[0135] Clause 7. The apparatus of any one of clauses 1-6, wherein the electrical stimulation has a programmable stimulation frequency between 1 Hz and 500 Hz.

[0136] Clause 8. The apparatus of any one of clauses 1-7, wherein the electrical stimulation unit is configured to automatically vary one or more stimulation parameters of the electrical stimulation over time.

[0137] Clause 9. A system for transdermal electrical stimulation, the system comprising: an electrode array; an attachment mechanism configured to secure the electrode array over a body portion of a user; and an electrical stimulation unit configured to deliver electrical pulses to the electrode array according to a programmable pulse sequence during one period of electrical stimulation, wherein the programmable pulse sequence comprises at least two consecutive cathodic pulses delivered via at least one electrode in the electrode array, wherein pulse amplitudes for the at least two consecutive cathodic pulses are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

[0138] Clause 10. The system of clause 9, wherein the attachment mechanism comprises a support member configured to be worn over an ear of the user, wherein the electrode array is disposed on the support member.

[0139] Clause 11. The system of any one of clauses 9-10, wherein the electrode array comprises a first electrode and a second electrode, wherein the at least two consecutive cathodic pulses are delivered via the first electrode by imposing corresponding anodic pulses at the second electrode.

[0140] Clause 12. The system of any one of clauses 9-11, wherein the electrode array comprises at least two first electrodes and two or more second electrodes, wherein the at least two consecutive cathodic pulses are respectively delivered via the at least two first electrodes by imposing corresponding anodic pulses at the two or more second electrodes.

[0141] Clause 13. The system of clause 12, wherein the two or more second electrodes are positioned around or on opposite sides of the two first electrodes.

[0142] Clause 14. The system of any one of clauses 9-13, wherein the attachment mechanism is configured to secure the at least one electrode to a first side of the body portion and secure at least another electrode in the electrode array to a second side of the body portion that is opposite to the first side.

[0143] Clause 15. The system of any one of clauses 9-14, wherein the programmable pulse sequence further comprises a passive charge balance pulse delivered via the at least one electrode after delivering the at least two consecutive cathodic pulses.

[0144] Clause 16. The system of any one of clauses 9-15, wherein the electrode array comprises a first group of electrodes and a second group of electrodes spaced apart from the first group of electrodes, wherein the at least two consecutive cathodic pulses form a first group of consecutive cathodic pulses, wherein the programmable pulse sequence further comprises a second group of consecutive cathodic pulses, wherein the first group of consecutive cathodic pulses are delivered via the first group of electrodes by imposing corresponding anodic pulses at the second group of electrodes, wherein the second group of consecutive cathodic pulses are delivered via the second group of electrodes by imposing corresponding anodic pulses at the first group of electrodes,

[0145] Clause 17. A method for transdermal electrical stimulation, the method comprising: delivering, during one period of electrical stimulation, a plurality of electrical pulses to an electrode array attached to a body portion of a user according to a predefined pulse sequence, wherein delivering the plurality of electrical pulses comprises delivering two or more consecutive cathodic pulses via at least one electrode in the electrode array, wherein pulse amplitudes of the at least two consecutive cathodic pulses are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors using a single cathodic pulse.

[0146] Clause 18. The method of clause 17, wherein delivering the plurality of electrical pulses further comprises delivering a passive charge balance pulse via the at least one electrode after delivering the two or more consecutive cathodic pulses.

[0147] Clause 19. The method of any one of clauses 17-18, wherein the two or more consecutive cathodic pulses define a first group of consecutive cathodic pulses, wherein delivering the plurality of electrical pulses further comprises delivering a second group of consecutive cathodic pulses via at least another electrode in the electrode array that is different from the at least one electrode to which the first group of consecutive cathodic pulses are delivered.

[0148] Clause 20. The method of any one of clauses 17-19, further comprising ramping up or ramping down the pulse amplitudes of the at least two consecutive cathodic pulses during a time window spanning multiple periods of the electrical stimulation.Example Alternatives

[0149] The disclosed stimulation protocols are exemplary and not intended to be limiting, as various alternative stimulation patterns may be implemented to achieve similar or enhanced effects. For instance, rather than delivering two consecutive cathodic pulses in a duplet via two adjacent electrodes or a single electrode, it is possible to apply three consecutive cathodic pulses, each separated by predefined inter-pulse intervals, using three adjacent electrodes or a single electrode. In some examples, four or more consecutive cathodic pulses can be delivered through one or multiple electrodes, depending on the desired stimulation effect. These extended sequences of cathodic pulses can induce or further enhance the facilitatory effect, potentially optimizing the excitability of mechanoreceptors and nerve fibers in targeted regions.

[0150] The technologies from any example can be combined with the technologies described in any one or more of the other examples. In view of the many possible examples to which the principles of the disclosed technology can be applied, it should be recognized that the illustrated embodiments are examples of the disclosed technology and should not be taken as a limitation on the scope of the disclosed technology. Rather, the scope of the claimed subject matter is defined by the following claims and their equivalents.

Claims

What is claimed is:

1. An apparatus for transdermal electrical stimulation, the apparatus comprising: one or more first electrodes; one or more second electrodes spaced apart from the one or more first electrodes; and an electrical stimulation unit configured to generate a programmable pulse sequence during one period of electrical stimulation, wherein the programmable pulse sequence comprises a first cathodic pulse followed by a second cathodic pulse, wherein the first cathodic pulse and the second cathodic pulse are delivered via the one or more first electrodes by imposing, respectively, a first anodic pulse and a second anodic pulse at the one or more second electrodes.

2. The apparatus of claim 1 , wherein an inter-pulse interval between the first cathodic pulse and the second cathodic pulse is programmable between 0 ps and 2000 ps.

3. The apparatus of claim 1 , wherein a pulse width of the first cathodic pulse and the second cathodic pulse is programmable between 10 ps and 1000 ps.

4. The apparatus of claim 1 , wherein pulse amplitudes for both the first cathodic pulse and the second cathodic pulse are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

5. The apparatus of claim 4, wherein the pulse amplitudes for both the first cathodic pulse and the second cathodic pulse are programmable between 0.1 mA and 5.0 mA.

6. The apparatus of claim 4, wherein the pulse amplitude for the first cathodic pulse is equal to or lower than the pulse amplitude for the second cathodic pulse.

7. The apparatus of claim 1, wherein the electrical stimulation has a programmable stimulation frequency between 1 Hz and 500 Hz.

8. The apparatus of claim 1, wherein the electrical stimulation unit is configured to automatically vary one or more stimulation parameters of the electrical stimulation over time.

9. A system for transdermal electrical stimulation, the system comprising: an electrode array; an attachment mechanism configured to secure the electrode array over a body portion of a user; and an electrical stimulation unit configured to deliver electrical pulses to the electrode array according to a programmable pulse sequence during one period of electrical stimulation, wherein the programmable pulse sequence comprises at least two consecutive cathodic pulses delivered via at least one electrode in the electrode array, wherein pulse amplitudes for the at least two consecutive cathodic pulses are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

10. The system of claim 9, wherein the attachment mechanism comprises a support member configured to be worn over an ear of the user, wherein the electrode array is disposed on the support member.

11. The system of claim 9, wherein the electrode array comprises a first electrode and a second electrode, wherein the at least two consecutive cathodic pulses are delivered via the first electrode by imposing corresponding anodic pulses at the second electrode.

12. The system of claim 9, wherein the electrode array comprises at least two first electrodes and two or more second electrodes, wherein the at least two consecutive cathodic pulses are respectively delivered via the at least two first electrodes by imposing corresponding anodic pulses at the two or more second electrodes.

13. The system of claim 12, wherein the two or more second electrodes are positioned around or on opposite sides of the two first electrodes.

14. The system of claim 9, wherein the attachment mechanism is configured to secure the at least one electrode to a first side of the body portion and secure at least another electrode in the electrode array to a second side of the body portion that is opposite to the first side.

15. The system of claim 9, wherein the programmable pulse sequence further comprises a passive charge balance pulse delivered via the at least one electrode after delivering the at least two consecutive cathodic pulses.

16. The system of claim 9, wherein the electrode array comprises a first group of electrodes and a second group of electrodes spaced apart from the first group of electrodes, wherein the at least two consecutive cathodic pulses form a first group of consecutive cathodic pulses, wherein the programmable pulse sequence further comprises a second group of consecutive cathodic pulses, wherein the first group of consecutive cathodic pulses are delivered via the first group of electrodes by imposing corresponding anodic pulses at the second group of electrodes, wherein the second group of consecutive cathodic pulses are delivered via the second group of electrodes by imposing corresponding anodic pulses at the first group of electrodes,17. A method for transdermal electrical stimulation, the method comprising: delivering, during one period of electrical stimulation, a plurality of electrical pulses to an electrode array attached to a body portion of a user according to a predefined pulse sequence, wherein delivering the plurality of electrical pulses comprises delivering two or more consecutive cathodic pulses via at least one electrode in the electrode array, wherein pulse amplitudes of the at least two consecutive cathodic pulses are lower than an excitation threshold associated with excitation of subcutaneous mechanoreceptors and nerve fibers using a single cathodic pulse.

18. The method of claim 17, wherein delivering the plurality of electrical pulses further comprises delivering a passive charge balance pulse via the at least one electrode after delivering the two or more consecutive cathodic pulses.

19. The method of claim 17, wherein the two or more consecutive cathodic pulses define a first group of consecutive cathodic pulses, wherein delivering the plurality of electrical pulses further comprises delivering a second group of consecutive cathodic pulses via at least another electrode in the electrode array that is different from the at least one electrode to which the first group of consecutive cathodic pulses are delivered.

20. The method of claim 17, further comprising dynamically varying one or more stimulation parameters of the electrical stimulation over a therapeutic session.

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