Surface electrical neurostimulation delivery as haptic

Abstract

A system is described that may deliver haptic feedback by applying electrical stimulation to a first region of a user's body to induce a second region of the user's body to experience a natural sensory level in response to an action occurring in a simulated remote environment and the intensity of the action. The system includes a controller that sets a parameter for the electrical stimulation based on an action occurring in the simulated remote environment and an intensity of the action. The system also includes a signal generator that generates an electrical stimulus including a parameter. The system also includes a skin surface electrode placed at a first location on the user's body to deliver electrical stimulation having a parameter to nerves at or near a first region of the user's body, the first location being remote from a second location on the user's body.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 352,654, filed on June 16, 2022, entitled “SURFACE ELECTRICAL NERVESTIMULATION DELIVERED AS HAPTIC FEEDBACK TO CAUSE A USER TO EXPERIENCE NATURAL SENSATION” and also claims the benefit of U.S. Provisional Application No. 63 / 394,319, filed on August 2, 2022, entitled “SURFACE ELECTRICAL NERVE STIMULATION DELIVERED AS HAPTIC FEEDBACK TO CAUSE A USER TO EXPERIENCE NATURAL SENSATION”. The entire contents of these provisional applications are incorporated herein by reference for all purposes. Technical Field

[0003] The present disclosure relates generally to tactile feedback delivered via electrical neural stimulation and, more particularly, to systems and methods for delivering surface electrical neural stimulation to nerves at or near a first region of a user's body to induce a second region of the user's body to experience a natural sensation as tactile feedback. Background Art

[0004] As the gaming industry evolves to include different and more advanced technologies, users are able to experience extended reality (XR) scenarios. XR (or even real environments located remotely from the user) can become more realistic to the user when tactile feedback is delivered as actions occur in the simulated remote environment. Haptic feedback generally refers to the use of touch to communicate with one or more users. Current tactile feedback technologies such as vibration motors, force feedback exoskeletons, and pneumatic airbag systems do not provide a natural representation of touch associated with actions occurring in the simulated remote environment, hinder user movement, and are bulky, fixed, and / or have limited workspaces. Electrical nerve stimulation can be used to provide an alternative to traditional tactile feedback.

[0005] Currently, electrical nerve stimulation used to provide tactile feedback is often described as uncomfortable or known to cause paresthesia / numbness. Additionally, such electrical nerve stimulation is delivered directly to the location where the sensation is intended to be felt, which may hinder the user's movement and function. Recently, a more realistic electrical nerve stimulation method using a new waveform has been developed for use with implanted electrodes that are in direct contact with the nerves of a person with limb loss. However, for people without limb loss, it is impractical to implant electrodes into the user's body in conventional XR applications. Summary of the invention

[0006] Described herein is a non-invasive method for tactile feedback using electrical neural stimulation, wherein surface electrical stimulation of nerves at or near a first region of a user's body is performed using one or more surface electrodes to induce the person to perceive a natural sensation occurring at a second region of the user's body for use as tactile feedback associated with a simulated remote environment, which may exist in extended reality (XR) or may be a real environment remote from the user.

[0007] In one aspect, the present disclosure may include a system that can apply electrical stimulation to a first area in a user's body to induce a second area in the user's body to experience a natural level of sensation in response to an action occurring in a simulated remote environment and the intensity of the action. The system includes a controller that can be configured to set parameters for the electrical stimulation based on the action occurring in the simulated remote environment, the location of the action occurring in the simulated remote environment, and the intensity of the action occurring in the simulated remote environment. The system also includes a signal generator coupled to the controller, which can be configured to generate electrical stimulation including the parameters. The system also includes at least one skin surface electrode coupled to the signal generator, the at least one skin surface electrode can be configured to be placed at a first location on the user's body, the first location being away from a second location on the user's body. Applying electrical stimulation with the parameters to a nerve at a first location on the user's body induces a second location on the user's body to experience a natural level of sensation in response to an action occurring in the simulated remote environment and the intensity of the action occurring in the simulated remote environment.

[0008] In another aspect, the present disclosure may include a device configured to apply electrical stimulation to at least a portion of a user's wrist, palm, elbow, forearm, and / or hand to a first area of ​​the user's body to induce a second area of ​​the user's body to experience a natural level of sensation in response to an action occurring in a simulated remote environment and the intensity of the action. The device includes at least one skin surface electrode, which may be configured to apply electrical stimulation with parameters to a nerve at a first location on the user's wrist, palm, elbow, forearm, and / or hand to induce a second location on the user's fingertip, finger, or hand to experience feedback in response to the occurrence of an action in a simulated remote environment and the intensity of the action, wherein the skin surface electrode is coupled to a signal generator that defines the electrical stimulation with parameters, and the signal generator is coupled to a controller that defines the parameters. The device also includes a fixture for fixing the surface electrode to the user's wrist, palm, elbow, forearm, and / or hand. It should be noted that the device (e.g., a glove) itself can be a fixture.

[0009] In another aspect, the present disclosure may include a method for applying electrical stimulation to a first area of ​​a user's body to induce a second area of ​​the user's body to experience a natural level of sensation in response to an action and the intensity of the action occurring in a simulated remote environment. The method includes: receiving, by a controller, an action and the intensity of the action occurring in a simulated remote environment; setting, by the controller, parameters for the electrical stimulation based on the action and the intensity of the action; and sending, by the controller, the parameters for the electrical stimulation to a signal generator. The signal generator generates an electrical stimulation signal including the parameters, and sends the electrical stimulation signal to a skin surface electrode to transmit the electrical stimulation signal to a nerve at a first location on the user's body to induce a second location on the user's body to experience a level of sensation in response to the action and the intensity of the action occurring in the simulated remote environment.

[0010] In another aspect, a method is described that can be performed by a controller and / or a signal generator to assign stimulation parameters to different surface electrodes associated with an action occurring in a simulated remote environment. The surface electrodes can transmit the stimulation to a nerve at a first location of one or more surface electrodes so that a second location experiences a sensation associated with the action. The second location can be different from the first location so that stimulation of a nerve at or near the first location can cause a distal referred sensation at the second location. For example, the location receiving the stimulation can be on the hand, while the second location can be on a fingertip. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The above and other features of the present disclosure will become apparent to those skilled in the art to which the present disclosure relates after reading the following description with reference to the accompanying drawings, in which:

[0012] Figure 1 is a diagram illustrating an example system according to one aspect of the present disclosure that can be used to deliver surface electrical nerve stimulation at a nerve at or near a first region of a user's body to induce a second region of the user's body to experience a natural sensation as tactile feedback;

[0013] Figure 2 It is shown by Figure 1 A diagram of a system for performing example electrical nerve stimulation at a nerve at or near a first location to induce a referred sensation at a second location;

[0014] Figure 3 It shows Figure 1 Figure 1 shows an example usage of the system in an extended reality (XR) application.

[0015] Figure 4 It shows Figure 3 Figure 2 shows an example of a sensing device;

[0016] Figure 5 It shows Figure 1 A diagram of the components of a system and the communications between computing systems;

[0017] Figure 6 and Figure 7 is a flow chart illustrating a method according to another aspect of the present disclosure for delivering surface electrical nerve stimulation to nerves at or near a first region of a user's body to induce a second region of the user's body to experience a natural sensation as tactile feedback;

[0018] Figure 8 and Fig. 9 each shows an example electrical waveform that may be used for stimulation to induce referred sensations;

[0019] Fig.10 is a diagram showing the experimental electrode positions;

[0020] Fig.11 and Fig.12 A graphical representation of the experimental results is shown;

[0021] Fig.13 is a diagram of an example sensory location for the subject;

[0022] Fig.14 and Fig.15 A graphical representation of the experimental results is shown;

[0023] Fig.16 and Fig.17 is a diagram showing the perceived location results; and

[0024] Fig.18 A graphical representation of the experimental results is shown. DETAILED DESCRIPTION

[0025] I. definition

[0026] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure belongs.

[0027] As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise.

[0028] As used herein, the terms “include” and / or “comprises” may specify the presence of stated features, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components and / or groups.

[0029] As used herein, the term "and / or" may include any and all combinations of one or more of the associated listed items.

[0030] As used herein, the terms "first", "second", etc. should not limit the elements described by these terms. These terms are only used to distinguish one element from another element. Therefore, without departing from the teachings of the present disclosure, the "first" element discussed below may also be referred to as the "second" element. Unless otherwise explicitly indicated, the order of operations (or actions / steps) is not limited to the order shown in the claims or drawings.

[0031] As used herein, the term "haptic feedback" may refer to the use of touch to communicate with one or more users. When used in conjunction with an alternative reality application, haptic feedback may be delivered in response to actions occurring in a simulated remote environment. As used herein, haptic feedback may be delivered via electrical nerve stimulation. When delivered via electrical nerve stimulation, haptic feedback may provide a natural feeling to the user.

[0032] As used herein, the term "natural sensation" may refer to an induced perception that mimics and / or replicates the physical sensation of an action occurring in a simulated and / or remote environment. Natural sensation may be different from the sensation caused by mechanical stimulation. In some cases, perception may be induced via electrical neural stimulation of one or more sensory nerves. Natural sensation may be felt as a referred sensation away from the location where the electrical neural stimulation is applied.

[0033] As used herein, the term "referred sensation" relates to a somatosensory sensation that is perceived as arising from a body part other than, but associated with, the body part being stimulated. For example, a distal referred sensation may be induced by stimulating a nerve at or near a first location to induce a somatosensory sensation at a second location (e.g., a fingertip) that is associated with the first location (e.g., connected to the same nerve, the same nerve root, the same vertebral level, etc.). A referred sensation may at least approximate a natural sensation.

[0034] As used herein, the term "electrical neural stimulation" may refer to the delivery of one or more electrical pulses (current and / or voltage) to cause one or more nerves to conduct one or more action potentials. Electrical neural stimulation and "electrical stimulation" may be used interchangeably herein. Examples of electrical pulses may include square waves, rectangular waves, ramp waves, logarithmic waves, exponential waves, etc. The electrical pulse may be a single pulse, but may also include a pattern of two or more pulses.

[0035] As used herein, the term "simulated environment" (also referred to as "simulated remote environment") may refer to an at least partially computer-implemented environment that a user may experience and / or interact with, including, but not limited to, locations, objects, simulated organisms, and other users of the at least partially computer-generated environment. The term "remote" may refer to the environment being at least partially computer-implemented. For example, actions may occur in the simulated remote environment, which actions may be controlled by or occur to the user. The simulated remote environment may exist in an extended reality (XR), and / or may be a real (real world) environment remote from the user.

[0036] As used herein, the term "extended reality" or "XR" is a general term that can refer to any real and / or virtual combined environment and human-computer interaction (e.g., motion and visual / tactile feedback) generated by computer technology and / or wearable devices (e.g., head-mounted displays, smart glasses, etc.). XR can include a virtual range from partial sensor input to immersive virtual reality. XR includes, but is not limited to, representative forms such as augmented reality (AR), mixed reality (MR), virtual reality (VR), and areas between them. An example of XR is full VR, in which the simulated remote environment is completely computer-implemented and does not include real-world environmental constraints beyond set boundary conditions. Another example of XR is AR, in which the simulated remote environment is partially computer-implemented and partially involves the real environment and is enhanced by the computer-implemented part.

[0037] As used herein, the term "intensity" of an action occurring in a simulated remote environment can refer to a measurable quantity of a property associated with the action. For example, the force associated with the action. The intensity of the action can be reflected in the electrical stimulation signal by changing one or more parameters related to the force and / or one or more parameters related to the timing.

[0038] As used herein, the term "skin surface electrode" may refer to an electrode that may be placed on or near the surface of a user's skin to transmit electrical signals through the user's skin. For example, one or more skin surface electrodes may be positioned at a first region of a user's body (e.g., in a predefined location within a glove or other device worn by the user) to deliver at least a portion of the electrical stimulation to the first region of the user's body to induce a second region of the user's body to experience a natural level of sensation.

[0039] As used herein, the term “user” may refer to one or more persons who may be immersed in an XR environment and / or a simulated remote environment.

[0040] II. Overview

[0041] When tactile feedback is delivered as actions occur in the simulated remote environment, the simulated remote environment (e.g., in extended reality (XR) and / or in a real environment away from the user) can become more realistic for the user. However, current tactile feedback technologies fail to provide a natural representation of touch associated with actions occurring in the simulated environment, and / or severely hinder the user's real-life mobility when used. Electrical nerve stimulation can be used to provide an alternative to traditional tactile feedback. However, currently available electrical nerve stimulation for providing tactile feedback is often described as uncomfortable or known to cause paresthesia / numbness. Additionally, such electrical nerve stimulation stimulation is intended to feel the location of the sensation (e.g., the sensation on the fingertips comes from the stimulation of electrodes on the fingertips), which may hinder the user's movements and functions. Recently, an electrical nerve stimulation that uses implanted electrodes and a new waveform to provide significantly more realistic sensations has been developed for people with limb loss. The implanted electrodes are in direct contact with the nerves of people with limb loss, but for people without limb loss, it is impractical to implant electrodes into the user's body in conventional XR applications.

[0042] The present disclosure describes a non-invasive method of tactile feedback in the form of a referred sensation. Tactile feedback is delivered using electrical nerve stimulation to create a more realistic natural sensation based on a recently developed electrical nerve stimulation method modified to be delivered through one or more surface electrodes. It is noteworthy that the surface electrodes are placed at locations that do not hinder the user's movement, but can provide referred sensations to different locations through underlying nerves. The sensation of tactile feedback (e.g., the natural sensation of touch) is experienced at the location (e.g., one or more locations) of any object (e.g., an object within an application using XR) for which tactile feedback is delivered via referred sensation by stimulating nerves at or near a first area that is neurologically associated with the felt location but not at the felt location (e.g., fingertips). This method targets nerves that connect the brain to areas (e.g., on fingertips) where sensory receptors exist, and as stimulation activates those nerves from locations (e.g., along the fingers), the brain associates the neural activity with sensations occurring at areas on the fingertips that are connected to those nerves, even if the sensory receptors in these areas on the fingertips have not yet been activated by physical contact, force, or direct stimulation. Accordingly, the systems and methods described herein can deliver surface electrical stimulation at a first area of ​​a user's body to induce a second area of ​​the user's body to experience a natural sensation as tactile feedback from a simulated remote environment that can exist in XR or can be a real environment located away from the user. It should be noted that this stimulation mechanism targets nerves rather than mechanoreceptors to provide a sensation at a location different from the stimulation location.

[0043] III. system

[0044] One aspect of the present disclosure relates to a non-intrusive method for providing tactile feedback to a user in a simulated remote environment, wherein the simulated remote environment may be an extended reality (XR) or may be a real environment located remotely from the user. Figure 1 As shown, system 10 can be used to deliver surface electrical nerve stimulation to nerves at a first area of ​​a user's body to induce a second area of ​​the user's body to experience a natural sensation as tactile feedback. The referred sensation is due to the transmission of afferent action potentials from peripheral sensory nerves to the spinal cord and then to the brain, which perceives the action potentials as sensory information from the second area. Although the figures show tools from an XR environment (e.g., at least a partially virtual environment), it will be understood that system 10 can operate in any simulated remote environment (e.g., in an environment that is real but remote from the user).

[0045] The system includes an XR device 12, which can be configured to display visual (and optionally, audio) information related to a simulated remote environment to a user (e.g., through a display of the XR device 12), and / or control at least a portion of the simulated remote environment (e.g., through a physical computer system acting as a controller, and / or motion sensing capabilities of the XR device 12 (e.g., provided by sensors and / or tracking devices). Accordingly, the XR device 12 may include processing and control components, as well as visualization components that may allow a user to see at least some elements of the simulated environment. Optionally, the XR device may also include an audio component (e.g., a speaker) to allow a user to hear at least some elements of the simulated environment. When an action occurs in the simulated environment (or after an action occurs in the simulated environment), the XR device 12 may facilitate tactile feedback to the user, wherein the tactile feedback is related to the action in the simulated environment. The action may be at least one of an action performed by the user, an action occurring to the user, an interaction between the user and an object, surface, or other aspect of the simulated remote environment, and the like (it should be understood that the XR device may also transmit a signal to a controller 14, a game engine, and the like). For example, the XR device 12 may facilitate tactile feedback to the user by wirelessly transmitting a signal indicating the type of action in the simulated remote environment, the position of the action relative to the user, and / or the intensity of the action. In such cases, the XR device may also include at least a wireless transmitter, and in some cases may include a wireless receiver and / or a wireless transceiver. The XR device 12 may also include a non-transitory memory that stores instructions, and a processor (which may include a non-transitory memory) for accessing the stored instructions and executing the stored instructions to perform tasks required for the operation. At least some of the tasks required for the operation may include running a game or simulation of the remote environment, visualizing the game or simulation, receiving movements made by the user and inputting the movements into the game or simulation, etc. Although labeled as an "XR" device, it should be understood that the XR device 12 may be a device that facilitates visualization and tactile feedback associated with any at least partially simulated environment.

[0046] System 10 may include a controller 14 (e.g., a microcontroller) that may include a non-transitory memory storing instructions, and a processor (which may include a non-transitory memory) for accessing the stored instructions and executing the stored instructions to perform tasks required for operation. Controller 14 may communicate wirelessly with XR device 12 at least in part by receiving signals indicating an intensity of an action, a location of an action, and / or a nature of an action in a simulated remote environment. Controller 14 may include at least one of a wireless transmitter, receiver, or transceiver (not shown) for wirelessly receiving and / or transmitting signals, data, and / or information directly from XR device 12. As another example, controller 14 may communicate wirelessly with XR device 12 such as, for example, Figure 5The controller 14 may communicate with a device such as a game engine of the computing system 52 shown in FIG. 1 , wherein the XR device 12 may communicate wirelessly with the computing system (including at least one wireless communication device not shown), and the computing system may communicate with the controller 14 via a wired connection. The controller 14 may determine the nature of the action, the intensity of the action, the location of the action, and the duration of the action, and determine one or more parameters required for the electrical stimulation (to reflect the intensity, force, location, and / or timing of the involved sensation for the action).

[0047] The controller 14 may be coupled to the signal generator 16 via a wired and / or wireless connection. Although not shown, in some cases, the signal generator 16 and the controller 14 may be implemented as a single device. The controller 14 may send a signal to the signal generator 16 indicating one or more parameters required for the electrical stimulation (e.g., pulses or pulse patterns) to be applied to the user to generate the involved sensation for the action simulating the remote environment. Upon receiving the signal from the controller 14, the signal generator 16 may generate an electrical signal having the one or more parameters and send the electrical signal to at least one of the one or more skin surface electrodes 18 that may be positioned on the user's skin. As an example, the one or more parameters may include (but are not limited to) pulse width, frequency, amplitude, pulse shape, pulse interval, charging phase amplitude, charging delay, etc. The types of stimulation referred to herein may include patterned stimulation intensity (or Ψstim), which may refer to the change of one or more stimulation parameters so that the pulse or pulse pattern in the stimulation signal may provide and / or reflect a specific intensity of the action. For example, the patterned stimulation intensity may include a stimulation waveform (also referred to as electrical stimulation) having a pulse amplitude (PA) that is first adjusted (e.g., during a calibration phase prior to use of the system 10 via the controller 14) to achieve a maximum pulse width (PW) range within the capabilities of the simulator (e.g., skin surface electrodes 18). During use of the system 10, the pulse width (PW) of the stimulation waveform may be adjusted (by the controller 14) to adjust the intensity of the referred sensation based on the action at the time (e.g., the user's hand interacting with a virtual and / or remote object), the frequency of the stimulation waveform may be adjusted (by the controller 14) to adjust the frequency of the referred sensation (e.g., continuous or tapping sensations, and tapping speed), and the symmetry and shape of the stimulation waveform may be varied (by the controller 14) to adjust the quality of the felt referred sensation based on the action.

[0048] The controller 14 may change at least one of the one or more parameters in response to an action or intensity of an action in a simulated remote environment that changes over time. This makes the experience of using the system 10 more realistic and / or more detailed than current XR or remote control systems. The action may be at least one of an action performed by a user, an action occurring to a user, an interaction between a user and an object, surface, or other aspect in a simulated remote environment, etc. Therefore, depending on the specific action itself, one or more involved sensations may be sent to the user for each time point of the action via one or more changes to one or more parameters of the electrical signal.

[0049] The controller 14 may determine an area of ​​the user's body that should feel tactile feedback via an implicated sensation based on a signal received from the XR device related to an action in the simulated remote environment. The controller 14 may select which of the one or more skin surface electrodes 18 should deliver electrical stimulation so that an appropriate area of ​​the body receives tactile feedback as an implicated sensation. For example, each of the one or more skin surface electrodes 18 may be positioned at a different location on the user's body. The location of each of the one or more skin surface electrodes 18 may be predetermined to cause an implicated sensation in a specific second location (the second location may be away from the location of a given electrode and different from the location of a given electrode) when stimulated. In such cases, the controller 14 may instruct the signal generator 16 to send an electrical signal having one or more parameters to at least one selected skin surface electrode of the one or more skin surface electrodes 18 to create an implicated sensation at and / or near a location of the user's body affected by an action in the simulated remote environment. In some cases, controller 14 may determine that electrical signals should be sent to more than one skin surface electrode 18, and the electrical signals sent to each of the more than one skin surface electrodes may be the same or different depending on the action and / or the intensity of the action.

[0050] As described above, the system 10 may include one or more skin surface electrodes 18 that can transmit electrical signals having one or more parameters from the signal generator 16 through the user's skin and to at least one nerve (e.g., at least one nerve near and / or below the location of each of the one or more skin surface electrodes that transmit the electrical signal). The one or more skin surface electrodes 18 may be coupled to the signal generator 16. The coupling may be via a wired connection, a wireless connection, or a combination of wired and wireless connections. In some cases, the system 10 may include a single skin surface electrode located at a first location on the user's skin to provide a sensation at a known second location (away from the first location) on the user's body. However, in other cases, the system 10 may include multiple skin surface electrodes located at multiple locations on the user's skin (e.g., each electrode at a different location), and each of the multiple skin surface electrodes that transmit the electrical signal may provide a referred sensation at a different second location (away from the stimulation location) on the user's body. The involved sensation at each of the different second locations can each have an intensity level (referred to as a sensation level), a nature (continuous or tapping), and / or a duration that can be based on one or more parameters of the electrical stimulation. For example, the involved sensation can be tactile feedback (providing neuromuscular stimulation as well as sensory stimulation), sensory feedback, and / or kinetic-based force feedback from a simulated remote environment.

[0051] Each of the one or more skin surface electrodes 18 may be placed at a location (first location) on the user's body that is distal to a second location of the user's body that is to receive the referred sensation. Figure 2 An example system 20 including only one skin surface electrode 18 is shown, but it should be understood that the following discussion can be applied to the above-mentioned Figure 1 Each of the one or more skin surface electrodes 18 discussed. Figure 2 As shown, the example system 20 may include a skin surface electrode 18, which may be located at a first location 22 on the user's skin and may receive an electrical signal from a signal generator 16. The electrical signal from the signal generator 16 may be transmitted by the skin surface electrode 18 through the user's skin to a nerve at or near the first location 22 on the user's skin. The electrical signal may stimulate the nerve at (or near) the first location 22. The nerve may be a sensory nerve that may send a nerve signal to the brain. In some cases, the nerve may be one or more sensory nerves and / or sensory fibers within the nerve. The stimulated sensory nerve may be stimulated based on the electrical signal transmitted by the skin surface electrode 18 (e.g., based on the sensory fibers within the nerve). Figure 1The brain associates the neural activity from the stimulation with sensations occurring at at least one second location 24 (which may be, for example, an area such as a fingertip area) to which the stimulated nerve (or nerves, if more than one nerve is stimulated) is connected, even though the sensory receptors in the second location have not been activated by direct stimulation, physical contact, or force.

[0052] Accordingly, the brain experiences a referred sensation at the second location 24. After the sensory neurons in the nerve at (or near) the first location 22 are sufficiently stimulated (e.g., the stimulation is greater than a threshold for conducting an action potential, which may be predefined or defined when the user first uses or calibrates), the referred sensation may be felt at the second location 24. An important condition for a nerve to be stimulated by an electrical signal is that the nerve must innervate both the first location 22 and the second location 24. For example, the second location 24 may be located along the same nerve as the first location 22 and further away from the spinal cord than the first location (e.g., the second location is far away from the first location). For example, the first location 22 may be a location on the wrist, palm, elbow, forearm, and / or hand, and the second location 24 may be a portion of a finger, and / or a portion of a hand away from the first location. In some cases, the first location 22 and / or the second location 24 may be located near a muscle. However, the first location 22 and / or the second location 24 need not be located near a muscle. It is important to note that the methods described herein do not target mechanoreceptors for traditional touch, pressure, vibration, and / or sound tactile feedback, but rather electrically stimulate nerves at a first location to induce a referred sensation at a second location different from the first location for tactile feedback purposes.

[0053] An electrical signal having one or more parameters is applied to the first location 22 via one or more skin surface electrodes 18 to stimulate nerves at or near the first location, inducing a second location 24 (e.g., remote from the first location) to experience a natural level of sensation (e.g., involved sensation) in response to an action and intensity of the action occurring in the simulated remote environment. For example, if the user is catching a ball (e.g., Figure 3 ), the electrical signal applied by the one or more skin surface electrodes at the first location 22 can make the user feel that they are actually catching the ball at the second location 24. An electrical signal with one or more different parameters can be applied to each of the one or more skin surface electrodes 18 so that the natural sensation at different second locations can mimic the feeling on the user's hand when catching the ball.

[0054] Stimulating the first location 22 with an electrical signal having one or more parameters (as described above) provides a referred sensation at the second location 24, which is a more natural sensation than the sensation induced by direct stimulation of the second location. For example, the user experiences less paresthesia from the referred sensation than direct electrical stimulation of the mechanoreceptors at the second location. Additionally, when the nerve is stimulated by transmitting an electrical signal from the skin surface electrode 18 (one of the one or more skin electrodes) located at the first location 22, the second location 24 experiences a more accurate location of the sensation than direct stimulation at the second location 24. It should be noted that the distance between the first location 22 and the second location 24 does not reduce the accuracy of the sensation (e.g., the exact intensity of the sensation). The accuracy of the sensation (e.g., the precision of the sensation) means that when the second location 24 receiving the sensation is the area (e.g., the area of ​​the hand) that should receive the sensation based on the action of the simulated remote environment, the system 20 transmits the referred sensation to the correct second location 24. For example, when grasping with the index finger in the simulated remote environment, the sensation transmitted by the system 20 is felt in the index finger instead of the little finger. In other words, the second location 24 is the area affected by the action in the simulated remote environment.

[0055] In some cases, such as Figure 3 As shown, the XR device 12 may be at least an XR head-mounted display device (or headphones) worn by a user, and ( Figure 1 The controller 14 and / or the signal generator 16 and the one or more electrodes 18 may be implemented in one or more sensing devices 32 that may be worn by a user (e.g., one or more sensing devices 32 on a user's hand, wrist, forearm, and / or elbow). Figure 3 The sensor devices 32 shown in FIG. 1 are worn on each hand of the user. The XR device 12 can provide the user with a visualization of at least one simulated remote environment. For example, Figure 3 A visualization of a simulated remote environment associated with a game in an alternate reality (AR) and / or virtual reality (VR) is shown, with a bouncing ball that can be caught by a user. The XR device 12 may be connected to and / or include a device that facilitates communication with one or more sensor devices 32 (e.g., Figure 5 At least a portion of the computing system 52 shown in , or a separate controller and / or wireless communication device).

[0056] One or more sensing devices 32 may be worn by a user and may (via Figure 1 The signal generator 16 of the present invention generates a stimulation signal (e.g., an electrical signal having one or more parameters) and can be connected to the skin via one or more skin surface electrodes (e.g., Figure 1 or Figure 2One or more skin surface electrodes 18) transmit the stimulation signal to a first location on the user. For example, the sensing device 32 can be a glove, a fingerless glove, a wristband, an armband, a sleeve, etc., which blocks the first location 22 (the location where the stimulation is applied) but does not block the second location 24 (a location away from at least one of the first locations where the involved sensation is felt). For example, when the second location 24 is a part of the fingertip, the sensing device 32 can cover the lower part of the finger, the hand and / or the wrist, and at least does not cover the corresponding fingertip. For example, keeping the fingertip uncovered allows the user to interact with real objects in AR normally and unhindered using the fingertip. The fingertip is just an example, and the sensing device 32 can be configured so that other parts of the finger, hand, palm, wrist, etc. may also not be blocked.

[0057] exist Figure 3 In the example of , as visualized by the XR device 12 in the pop-up portion, the action of catching a virtual ball can be accompanied by one or more feelings of catching the ball. The XR device 12 (and / or an attached computing device) can run a game in which a user catches a ball (e.g., basketball, baseball, football, four-square, dodgeball, etc.), for example, and the XR device can visualize a simulated remote environment for the game. The XR device 12 can detect that the user is catching the ball (or is about to catch the ball) for all time points during the action of catching (which should cause the feeling of catching the ball as if in real life) (e.g., through hand motion capture, motion sensors, position sensors, and external cameras, etc.), and can send a signal to the sensing device 32 for each time point. The sensing device 32 can receive a signal from the XR device 12 indicating that the virtual user is catching the ball (or is about to catch the ball) for each time point. The sensing device 32 (including the controller 14 and the signal generator 16 in addition to the one or more skin surface electrodes 18) can determine which of the one or more skin surface electrodes to stimulate, and one or more parameters for the electrical signal to be transmitted through each determined skin surface electrode, and then apply the electrical signal through the one or more skin surface electrodes to simulate the feeling of catching the ball through the involved sensation of the entire hand. The involved sensation can be as simple as a tingling sensation whose intensity increases with the time of catching the ball to show the impact force of the ball on the opponent, or it can be as detailed as a natural feeling including the on-site feeling of catching the ball with bare hands in real life. It should be understood that Figure 3 The example of is just a simple example, and system 10 can be used for XR devices and any other virtual reality, augmented reality, and / or remote system control applications for which traditional tactile or computer controls are currently used.

[0058] like Figure 4As shown, an example of a sensing device 32 can be a reusable fingerless glove that can be configured to cover at least a portion of a user's hand (e.g., a portion of the palm and / or back of the hand, and one or more fingers and / or thumbs), and leave at least a portion of one or more user fingers uncovered. However, other wearable sensing devices 23 can be used. For example, gloves may not be required, and the skin surface electrodes may be included in one or more straps or other devices designed to secure the skin surface electrodes. Alternatively or additionally, in other examples not shown, the sensor device 32 can be configured to be worn on the user's lower limbs (e.g., a sock-like device, a shoe-like device, a leg band, or a wrap, etc.) or on the torso (e.g., an adhesive patch, a body wrap, etc.).

[0059] like Figure 4 As shown, most or all of the user's fingers may not be covered by the glove. The glove may include one or more skin surface electrodes located at different first locations within the glove that contact the skin (in this example, at the base of each finger and thumb and at the wrist, shown as circles). Figure 4 Six skin surface electrodes are shown (but any number and any position inside the glove can be envisioned), each electrode is designed to stimulate a different second location (shown as six different stars, with dashed lines connecting each electrode to the corresponding stimulation location) to feel a given involved sensation at another location (e.g., one or more second locations). The second location is shown only as an example and depends on the first location of each skin surface electrode (e.g., each location has the same nerve running through it). The glove can include at least one fixing device to fix the skin surface electrode to the user's hand (e.g., Velcro, buttons, elastic bands, etc.). Alternatively, the glove itself can provide the fixing device (e.g., an elastic material that stretches and then fits to the user's hand / wrist when worn). In some cases, the skin surface electrodes can be located at predefined locations within the glove (e.g., to create a predefined electrode configuration, where the location of each skin surface electrode corresponds to the desired location where the sensation is experienced via feedback). The glove can have different sizes (e.g., small, medium, and large) for different users with hands of different shapes and / or sizes. The skin surface electrodes may activate the finger nerves and / or the nerves in the palm to induce a referred sensation in the corresponding second location. The referred sensation may be a tactile sensation such as touch force, pain, heat, etc.

[0060] Each skin surface electrode of the sensing device 32 can be configured to have a controller and a signal generator ( Figure 4 Not shown, but in Figure 1An electrical signal (also referred to as stimulation, electrical stimulation, stimulation signal) of one or more parameters configured by a position controller 14 and a signal generator 16 is applied to a nerve at or near the location of an electrode on the skin surface. As shown, the corresponding first location can be on the hand, palm or wrist, but it should be understood that the first location can also be on the elbow or forearm. As shown, the second location is on the fingertip or hand or palm. As described above, due to the action occurring in the simulated remote environment and the intensity of the action occurring, the second location can experience feedback (in the form of involved sensation) in response to the stimulation at the first location.

[0061] Figure 5 An example connection 50 between the XR device 12 and the controller 14 is shown. The XR device 12 may be connected to a computing system 52 in a bidirectional manner. The computing system 52 may be at least partially implemented as a part of the XR device 12 (e.g., a non-transitory memory and / or a processor), or may be a separate controller including at least one non-transitory memory and / or a processor. Figure 5 As shown, the connection between the XR device 12 and the computing system 52 can be wireless. However, the connection between the XR device 12 and the computing system 52 can be wired, or a combination of wired and wireless. The connection between the computing system 52 and the controller 14 is at least unidirectional (but can be bidirectional) and can be wired and / or wireless. The computing system 52 can communicate with additional components to provide tactile feedback in a networked remote operation system. It should be noted that the computing system 52 can include one or more devices that can be connected to the XR device 12, the controller 14, and any necessary additional devices. The computing system 52 can be, for example, a smart phone, a laptop, a desktop computer, a gaming system, a dedicated AR / VR device (when implemented as part of the XR device 12), and the like.

[0062] The computing system 52 may facilitate the creation of a simulated remote environment for XR (e.g., AR or VR, etc.) and / or in a real environment located remote from a user (e.g., controlling a machine at a remote location, and viewing and receiving feedback from the machine). As an example, in a real environment remote from the user, visual, audio, and tactile information from the remote environment may be transceived by the computing system 52, which may provide visual (and optionally, audio) to the XR device 12, and tactile information to the user through the controller 14. As another example, in a simulated remote environment, visual, audio, and tactile information stored in a memory (e.g., saved or transmitted game information) may be transceived by the computing system 52, which may provide visual (and optionally, audio) to the XR device 12, and tactile information to the user through the controller 14.

[0063] The example possibilities of tactile information (e.g., tactile feedback) are countless. For example, for immersive head-mounted VR, typical interactions between hands and simulated objects in a virtual environment can be displayed on the XR device 12, and the tactile sensations generated by the interactions can be felt as involved sensations by the user of the system 10. Typical interactions can include, but are not limited to, grabbing an object, feeling the sound waves emitted by a subwoofer, squeezing a bag of pastry frosting, crushing a piece of powder, feeling the texture of a washboard, feeling what a robot's mechanical sensors detect, finding objects buried in the sand, etc. For non-immersive VR, tactile sensations can come from a mobile device (phone, tablet, smart watch) with hand tracking capabilities using its built-in sensors (camera, laser, radar, time of flight, or other range or 3D sensors). Tactile feedback can also represent simulated or sensor-acquired information streams, such as magnetic or chemical signals detected by sensors.

[0064] As an example of real-world use of system 10 (and connection 50), computing system 52 may be used to facilitate the display of visual feedback (in the form of involved sensations) and tactile feedback of the real-world remote environment of a user's remotely controlled robotic avatar. Visual feedback may be displayed on an XR device 12 worn by the user, and the user's head or hand movements may be captured by XR device 12 (e.g., by one or more sensors (accelerometers, IMUs, gyroscopes, etc.) and / or cameras), and / or from one or more sensory devices ( Figure 5 The tactile sensation and force interaction generated between the robotic avatar and the remote environment are sensed by one or more sensors (e.g., force, accelerometers, IMUs, gyroscopes, etc.) on the robotic avatar, and can be received by software in the computing system 52 via the Internet or other public or private network, and can be provided to the user by the controller 14 as tactile feedback to achieve involved sensation using the above-mentioned stimulation technology. In short, the controller 14 can send electrical signals to the signal generator, and the signal generator can send electrical signals to one or more skin surface electrodes ( Figure 5(not shown), the one or more skin surface electrodes can transmit electrical signals to nerves at or near the location of the one or more skin surface electrodes, so that the user can feel the touch and force interactions generated at the remote environment (or a secure replica / approximation thereof) at a location away from the one or more skin surface electrodes. An example of a feedback loop for a robotic hand is the "display" (e.g., feel) of tactile information from tactile sensors mounted to the fingers of the robotic hand at a second location on the user's fingers, and simultaneous stimulation (via neuromuscular electrical stimulation (NMES)) of wrist extensors and flexors to "display" (e.g., feel) force information from joint torque sensors embedded in actuators in the wrist of the robotic hand. The movement of the robotic hand can be controlled via mirroring the hand movements of a human operator, and the hand movements of the human operator can be tracked by sensors on an immersive VR display worn by the human operator.

[0065] For example, for a simulated remote environment (e.g., an AR or VR application), computing system 52 may run a process for the AR or VR application (e.g., using a processor to run from non-transitory memory) and / or connect a user of system 50 with other users of the same simulated remote environment. The user may utilize XR device 12 (which may include a physical game controller and / or motion sensing capabilities) and / or controller 14 (which may be connected to Figure 5 In essence, as the user moves in real life, the user's virtual avatar moves in a similar or predetermined manner within the simulated remote environment run by computing system 52 and visualized through the display of XR device 12 (e.g., specific movements of the user cause different things to happen in the game, such as a flick of the wrist to open an in-application menu). Actions affecting the user within the simulated remote environment may be fed back to the user visually via computing system 52 and displayed on the display of the XR device, and may be controlled using controllers, signal generators ( Figure 5), and one or more skin surface electrodes to create an involved sensation at another location as tactile feedback, which is fed back to the user in a tactile manner through the game engine via the controller 14. For example, a user can hold another user's hand in a simulated remote environment and feel that they are shaking hands. In another example, the user can play a ball game (e.g., basketball, football, four-square, etc.) and can feel that he is catching and throwing the ball. In another example, the user can drive a vehicle and feel the vibration of the steering wheel and the force feedback of the steering wheel on the user's hand. In another example, the user can also interact with a physical game controller (e.g., a clicker, a racket, a fake sword, etc.) that is replicated as himself or other objects in the virtual world. Due to the system described in detail above, the user can feel the natural sensation of these actions, not just, for example, vibration or tingling or sharp jabs.

[0066] IV. method

[0067] Another aspect of the present disclosure may include a method for delivering surface electrical nerve stimulation to nerves at or near a first area of ​​a user's body (e.g., first location 22) to induce a second area of ​​the user's body (e.g., second location 24) to experience a natural sensation as tactile feedback (e.g., referred sensation). Referred sensation is due to the transmission of afferent action potentials from peripheral sensory nerves to the spinal cord and then to the brain, which perceives the action potentials as sensory information.

[0068] This method can utilize the system (such as Figure 1-Figure 5 The method provides a method of delivering surface electrical nerve stimulation at a first area of ​​a user's body to induce a second area of ​​the user's body to experience a natural sensation as tactile feedback (e.g., a referred sensation). At least one step in the method may be performed by at least one component including at least one processor.

[0069] For simplicity, the method is shown and described as being performed sequentially; however, it should be understood and appreciated that since some steps can occur in different orders and / or occur simultaneously with other steps shown and described herein, the present disclosure is not limited to the order shown. In addition, not all of the shown aspects are necessary to implement the method, and the method is not necessarily limited to the shown aspects.

[0070] Reference now Figure 6, a method 60 for delivering surface electrical neural stimulation to nerves at or near a first region of a user's body (e.g., first location 22) to induce a second region of the user's body (e.g., second location 24) to experience a natural sensation as tactile feedback is shown. At step 62, an action and an intensity of the action occurring in a simulated remote environment may be received from an XR device (e.g., XR device 12) and / or a computing system (e.g., by a controller 14, which may be a microcontroller). At step 64, one or more parameters for the electrical stimulation may be set (e.g., by the controller 14) based on the action and the intensity of the action in the simulated remote environment or the real environment (e.g., to provide a reflection of the nature, duration, location, and / or intensity of the action). As an example, the parameters may include (but are not limited to) pulse width, frequency, amplitude, pulse shape, pulse interval, charging phase amplitude, charging delay, etc. At step 66, the one or more parameters may be sent (e.g., by the controller 14) to a signal generator (e.g., to the signal generator 16) to configure the electrical stimulation. A signal generator (e.g., signal generator 16) generates an electrical stimulation signal including a parameter and sends the electrical stimulation signal to a skin surface electrode (e.g., one or more skin surface electrodes 18) to deliver the electrical stimulation signal to a nerve at or near a first location on the user's body (e.g., first location 22) to induce a second location on the user's body (e.g., second location 24) to experience a level of sensation in response to an action and intensity of the action occurring in a simulated remote environment.

[0071] It should be noted that the first location and the second location only need to be connected by a single nerve (e.g., a digital nerve), but in some cases may be connected by multiple neural structures. The same electrical signal or different electrical signals or a combination thereof may be sent to more than one skin surface electrode to induce referred sensations at more than one second location. This approach targets nerves that connect the brain to areas where sensory receptors exist (e.g., on the fingertips), and as stimulation activates those nerves from a certain location (e.g., along the finger), the brain associates the neural activity with sensations occurring at areas on the fingertips that are connected to those nerves, even if the sensory receptors in these areas on the fingertips have not been activated by physical contact, force, or direct stimulation.

[0072] Actions can take place in a simulated remote environment or in a real environment. Figure 7As shown in method 70, at step 72, a simulated remote environment may be displayed (e.g., by XR device 12), and at step 74, information about the motion and the intensity of the motion may be sent to a controller (e.g., controller 14). As described above, the XR device and the controller may communicate through at least one device (e.g., computing system 52) that may participate in an XR application or a real application. The XR device may also display a real environment that is real but physically remote from the user, and information about the real motion and the intensity of the motion at the physically remote location may be sent to the controller. The real motion may be based on a user command or action via a robot or other machine at a remote location.

[0073] V. Examples

[0074] The following examples illustrate different uses of the systems and methods described herein. These examples are not intended to be limiting in any way, but are merely intended to illustrate how the systems and methods work in everyday life. As described, in each of these examples, it is clear that electrical stimulation is delivered to a nerve at a first location for the purpose of feeling a referred sensation at another location along the nerve, rather than being delivered to a mechanoreceptor for direct sensing of the stimulation. Example waveforms that may be used to deliver a referred sensation are as follows: Figure 8-Figure 9 However, it should be understood that different waveforms with various waveform shapes, symmetries, and areas are possible (as long as the waveform is charge balanced).

[0075] Figure 8-Figure 9 Each of the waveforms shown in is biphasic (having a phase A and a phase B) and is charge balanced such that the area (charge) under the waveform for phase A is the same as the area (charge) under the waveform for phase B. Figure 8 and Fig. 9 are examples of charge balance waveforms. Figure 8 As shown, the waveform can be symmetrical (Phase A has the same shape as Phase B), while Fig. 9 As shown, the waveform can be asymmetric (phase A has a different shape than phase B). Figure 8 and Fig. 9 The waveforms all have a cathodic leading pulse (Phase A) followed by an anodic pulse (Phase B). Variations may be introduced using modulation, such as changing the shape (e.g., using a triangle instead of a square for every other pulse), and the pulse frequency, pulse width (PW), pulse amplitude (PA), and / or inter-pulse interval (IPI) may be varied.

[0076] Electrodes can be positioned to target specific nerves. To avoid activating motor nerves that innervate muscles, potentially causing convulsions, for example, electrodes can be placed behind the wrist. One such location is the proximal phalanx of each finger. Because electrical stimulation creates action potentials that spread in both the efferent and afferent directions on the digital nerves in the fingers, distal referred sensations can be generated on the corresponding fingertips. Because the dendrites of the afferent nerves can only receive signals (neurotransmitters) from the mechanoreceptors in the skin, but cannot activate the mechanoreceptors, the efferent action potentials transmitted to the fingers have no effect on the perceived sensation. The afferent action potentials are transmitted from the peripheral nerves to the spinal cord and then to the brain. The stimulated nerves are sensory nerves (because there are no motor nerves at the location of the active electrode), so the stimulated nerves carry sensory information exclusively from the mechanoreceptors. Therefore, when the brain receives action potentials from these nerves, the brain perceives the action potentials as sensory information from the mechanoreceptors (for example, the brain is deceived in terms of the source of the action potentials). Another example can include placing electrodes on the palm of the hand, which can cause sensations to be felt on multiple fingers because the nerves under the palm of the hand transmit to multiple fingers. The common return electrode may be placed remotely from the electrodes, such as applied to the user's elbow, to increase stimulation depth, increase the probability of distal referred sensation, restrict sensation to only referred locations, and / or avoid sensation regardless of where the return is placed.

[0077] video games

[0078] use Figure 1-Figure 5 One example of the system shown is for video gaming purposes. For example, a user may wear or use an XR device (e.g., a head mounted display, and any optional physical game controllers and / or sensors of the XR device) that includes a computing system or is connected (wired and / or wirelessly) to a computing system (e.g., a gaming laptop running a basic application, a mobile device, etc.). For example, the XR device and the computing system (or controller) may communicate wirelessly (e.g., via Bluetooth, Bluetooth Low Energy (BLE), and / or 915 MHz radio using different protocols and carrier frequencies).

[0079] Users can also wear reusable sensing devices, e.g. Figure 4The partial glove device shown and described in detail above, the glove device fixes one or more skin surface electrodes to the user's skin, and may include a controller and a signal generator that communicates with an XR device and / or a computing system. The sensing device may take other forms such as partial arm sleeves, wristbands, sock-like devices, etc. for sending involved sensations to different parts of the body. While playing a video game, the sensing device may receive information related to actions affecting the user in the game (nature, duration, intensity, etc. of the action) from the XR device and / or computing system, and convert these actions into tactile feedback at the fingertips, or other parts of the hand and / or body. The sensing device uses one or more signals configured based on the action in the game to stimulate one or more nerves using one or more skin surface electrodes at a first position. The stimulation is configured to cause involved sensations at a second position along one or more nerves (e.g., at the fingertips, or other parts of the hand and / or body that are away from the first position but connected by the same nerve) as tactile feedback. Importantly, the tactile feedback felt by the user is an involved natural sensation based on the stimulation at one or more first positions related to the action occurring in the video game and the intensity of the action. In this way, the user can feel what is happening in the game (or a safe replica / approximation if the virtual actions are too painful for the user in real life), making it more realistic. Sensing devices are also known for not hindering the user's ability to move freely and interact with the real world (e.g. in AR gaming applications).

[0080] Telepresence

[0081] Telepresence is about Figure 1-Figure 5 Another exemplary use of the described system for stimulating nerves using sensory stimulation via surface electrodes at a first location and receiving referred sensations at a second location. For example, a medical professional may wear a reusable partial glove (e.g., Figure 4 The glove can communicate with a robot at a remote location that has sensors and acts on the patient, or with a second glove that has one or more sensors (pressure, accelerometer, gyroscope, IMU, temperature, etc.) and is worn by the patient, who is instructed to make diagnostic movements and be touched by the user (e.g., feel heartbeat, breathing, temperature, nodules, lumps, etc.). Thus, medical professionals can interact with patients and perform diagnoses from a distance. Distant friends and relatives can communicate with each other via reusable partial gloves (such as Figure 4As shown, or other sensing devices 32) make physical contact (e.g., a virtual hug or handshake that a user of the gloves or other sensing devices can actually feel). Another example of remote presentation is that the user manipulates a machine (e.g., a drone, airplane, car, etc.) and / or a robotic avatar from a distance. Among them, the gloves or other sensing devices allow the user to receive natural-feeling tactile feedback corresponding to the actions of the machine and / or robotic avatar without interrupting the user's movement, for example, allowing the user to make limited changes to the actions of the machine and / or robotic avatar and feel the limited actions that affect the machine / robotic avatar. In this example, the sensing device can also be used to control the machine / robotic avatar via sensors included in the gloves and / or attached to the user (e.g., force sensors, pressure sensors, gyroscopes, IMUs, accelerometers, etc.), or another control device (e.g., joystick, keyboard, steering wheel, etc.) can be used with the gloves. Any sensations that are unsafe / too painful for the user can also be suppressed to a safe natural sensation level.

[0082] Feedback loop

[0083] Feedback loops can be used in any of the examples described herein. An example of a feedback loop is the display of tactile information from touch sensors mounted to the fingers of a robotic hand, and the simultaneous use of neuromuscular electrical stimulation (NMES) to the wrist extensors and flexors to display force information from joint torque sensors embedded in actuators in the wrist of the robotic hand. The movements of the robotic hand are controlled to mirror the hand movements of a human operator, and the hand movements of the human operator are tracked by sensors on an immersive VR display worn by the human operator. An example based on a video game is the display of tactile information representing vehicle vibrations propagating through a steering wheel, and the simultaneous use of force feedback from NMES to represent the torque applied by the steering wheel to the player's hand.

[0084] VI. Experiment

[0085] This experiment shows a study that evaluates the ability of surface electrical stimulation to generate distal referred sensations in people without limb loss, with the goal of eliciting sensations at the fingertips. The experiments in this study investigated the effects of electrode position, stimulation intensity, and stimulation polarity on the perceived location of sensations. The results showed that the finger-palm electrode combination was most likely to induce distal referred sensations. The position of the electrodes on the fingers and palm in the circumferential or anterior-posterior directions also affected the perceived location of distal referred sensations, but there was an inconsistent trend between participants. The study found that stimulation intensity also had a statistically significant effect on the location of sensation: an increase in stimulation intensity resulted in an increase in the area of ​​sensation, a proximal shift in the perceived center of mass, and a shift of the perceived distal boundary to a more distal location. The study found that 71% of the perceived sensations were not polarity dependent, and that a larger return electrode placed on the elbow eliminated sensations located near the return electrode and reduced proximal sensations located on the palm.

[0086] Experiment 1: Identification of electrode combinations that induce distal referred index finger sensations

[0087] Experiment 1 focused on the effects of inter-electrode distance, electrode position, and polarity on the generation of distal referred sensations of the index finger.

[0088] Experiment 1: Methods

[0089] Participants and Study Visits: Five able-bodied participants (two females, three males; age 28 ± 6 years (mean ± SD)) performed the experiments in a single 3.5-hour long experimental session. All participants provided written informed consent to participate in these experiments, which were approved by the Metropolitan Health System Institutional Review Board. The study was conducted in accordance with the principles embodied in the Declaration of Helsinki and local statutory requirements.

[0090] Stimulation system and parameters: These experiments used a custom-designed laboratory-grade stimulator from Case Western Reserve University. The stimulator can generate currents between 1 mA and 100 mA (with a resolution of 1 mA) and pulse widths between 0 µs and 255 µs (with a resolution of 1 µs). The stimulator was controlled by a custom MATLAB Simulink model on a host computer for selection of stimulation parameters. Disposable self-adhesive Ag|AgCl electrodes with a diameter of 1.8 cm were connected to the stimulator. The stimulator generated a cathode-first, charge-balanced, current-controlled, symmetrical output square wave. To generate continuous sensation, stimulation was applied at 90 Hz for five seconds.

[0091] Identification of possible electrode locations: At the beginning of each experimental session, the participants' hands were prepared using TENS wipes. Each participant's left hand and index finger were divided into 14 areas consisting of 8 areas in the index finger (IA, PA, IP, PP, IL, PL, IM, and PM) and 6 areas on the palm (PA1, PA2, PA3 and PP1, PP2, PP3) (see Fig.10 ). These 14 areas (subsequently referred to as "electrode locations") were placed proximal to the digital nerve branches of the median nerve that innervate the index finger. Each of the 8 areas on the finger was located at the center of the middle or proximal phalanx on each facet of the finger (medial, lateral, posterior, and anterior). Because the distal phalanx was the target location for eliciting sensations, and because sensations far from the distal phalanx could not be elicited, it was not evaluated. Fig.10 In the figure, the 14 electrode locations for Experiment 1 are indicated by dots. The locations on the fingers are concentrated on the surfaces of the following phalanges: medial anterior (IA) and posterior (IP), proximal anterior (PA) and posterior (PP), medial lateral (IL) and medial (IM), and proximal lateral (PL) and medial (PM). The palmar posterior (PP) and anterior (PA) locations are distributed at 1 / 3 of the distance from the knuckle to the horizontal plane of the ulnar styloid process (PP1, PA1), 2 / 3 of the distance (PP2, PA2), and 3 / 3 of the distance (PP3, PA3).

[0092] Distal referred sensations are defined as sensations that are located away from the most distal electrode location; since the electrode locations on the distal phalanges are on the most distal part of the finger, they cannot elicit this type of sensation. For the finger regions, the naming convention is a combination of the finger segment mentioned above (middle or proximal phalange) and the face of the segment (anterior, posterior, medial, or lateral). For example, an electrode location on the lateral face of the proximal phalanx is a PL electrode location (see Fig.10 ). The six palm electrode locations were defined while the participant's hand was placed on a flat surface and a guide line was drawn on the posterior side of the hand through the center of the fingers. The distance along the guide line from the knuckles to a horizontal line through the ulnar styloid was measured, and a point was placed every third of the distance (see Fig.10 ). The same process is repeated for the front side of the hand. In the naming convention for the palm electrode locations, the first letter is always P for palm, and the second letter represents the side of the palm (front or back), and the number is the distance from the finger in thirds.

[0093] To ensure that electrode positions were consistent throughout the study, each of these locations was marked on the participant's hand using a skin-safe marker. This approach ensured reproducibility across participants, regardless of hand size, by using anatomical landmarks. Each electrode position could have two polarities (active and return), so a total of 182 (14 × 13) combinations of electrode positions (subsequently referred to as electrode combinations) were evaluated.

[0094] Evaluation of electrode combinations: Participants were first asked to find their maximum comfort limit. To ensure that each participant's maximum comfort limit was less than 255µs (maximum pulse width of the stimulator), the pulse amplitude was set higher (15mA) than the 3mA amplitude reported in the literature to have an evoked sensation. Each participant was asked to control the pulse width using the scroll wheel of the computer mouse, so they could limit exposure to pulse widths that produced uncomfortable sensations. Then, participants were instructed to find the discomfort threshold by increasing the pulse width until discomfort was felt, and then immediately reducing the pulse width to find the highest pulse width that produced a comfortable sensation without discomfort. The simulation was turned on for five seconds each time to avoid possible desensitization. To ensure that participants had enough time to adjust the pulse width and judge the sensation, additional 5-second stimulation sequences were applied if necessary. To minimize variability associated with electrode reapplication, each electrode combination was evaluated for both polarities without moving the electrodes. Additionally, one of the electrode positions was kept constant, and the other electrode position was repositioned to 13 other electrode positions. This process was repeated a total of 14 times to cover all 182 different electrode combinations. During the entire experimental session, the electrodes were repositioned as needed to ensure adequate adhesion of the electrodes to the skin.

[0095] For each stimulus, participants were asked three questions: 1) Did it feel far away from the electrode location (yes or no)? 2) Did it feel comfortable (yes or no)? And 3) Did you feel the muscle contraction caused by the stimulus (yes or no)? Before starting the experiment, the researchers explained the instructions to the participants, and the participants were able to ask questions to deepen their understanding. Only electrode combinations for which the participants answered "yes" to both questions 1 and 2 and "no" to question 3 were classified as "helpful" sensations and were selected for further analysis.

[0096] Statistical Analysis: To compare different electrode locations and combinations, data were averaged across all five participants. When comparing different polarity conditions, data were averaged across participants to evaluate different electrode combinations and across electrode combinations to evaluate differences between participants. Polarity data were evaluated for normality using quantile-quantile (QQ) plots and histograms, but data did not conform to a normal distribution. Therefore, a nonparametric test, the Kruskal-Wallis rank-sum test, was used to investigate whether there were significant differences between polarity conditions. Post hoc pairwise comparisons were performed using the Dunn test for multiple combinations with a Bonferroni adjustment.

[0097] Experiment 1: Results

[0098] Data were pooled across participants and trials to determine how electrode location affected the frequency of reports of helpful sensations. Fig.11 Shown, (11a) are the mean percentage and standard deviation of useful trials for each electrode position relative to the total number of trials in which a particular electrode was used across all participants (n = 130 per electrode position), and for each electrode combination relative to all trials in which electrodes were placed at positions described by the combination (e.g., finger and palm) across all participants (n = 280 finger-finger, n = 480 finger-palm, n = 150 palm-palm). The top electrode positions most frequently associated with the useful classification, in descending order (from most frequently used to least frequently used), are PA1, IL, IA, PL, IM, IP, and PA (see ). Fig.11 , element a). The electrode locations least frequently associated with the helpful classification were, in ascending order (least frequently used to most frequently used), PA3, PP3, PP, PP2, PA2, PM, PP1. The majority of the least frequently used electrode locations were proximal palm electrode locations (5 / 7). When looking at different types of electrode combinations, 68% (n=480) of trials with a finger-palm electrode combination (one electrode location in the palm and one electrode location in the finger) were classified as helpful (see Fig.11, element b). In contrast, only 23% (n=150) of the palm-palm electrode combination trials were classified as useful. The top three electrode locations on the palm were PA1, PP1, and PA2, and the top three finger electrode locations were IL, IA, and PL. Based on these results, finger-palm combinations with proximal palm electrodes and fingers can elicit distal referred sensations. The finger-palm combinations using the top three finger and palm electrodes were as follows (for all n=10) IA-PA1 (100% useful), IL-PA1 (100% useful), PL-PA1 (90% useful), IA-PP1 (90% useful), IL-PP1 (100% useful), PL-PP1 (90% useful), IA-PA2 (90% useful), IL-PA2 (100% useful), PL-PA2 (70% useful). In addition, the location of both the active and return electrodes can affect the presence of distal referred sensations.

[0099] For a given electrode combination, there can be two possible arrangements, depending on the relative positions of the active and return electrodes. For example, a given finger-palm electrode configuration can have an active electrode placed on the palm, and a return electrode on the finger, or vice versa. The difference between these two arrangements is the polarity. Fig.12 Elements (a) and (b) show the mean percentage and standard deviation of polarity dependence relative to total useful trials, averaged across participants (n=280 finger-finger, n=480 finger-palm, n=150 palm-palm) for each electrode combination (12a), and averaged across electrode combinations for each participant (n=182 per participant) (12b). The legend specifies the polarity configuration and the relative position of the electrodes to each other. The third bar (orange) refers to Fig.10 The two electrodes are equidistant from the wrist.

[0100] On average, participants reported that 71% (n=910) of perceived sensations were polarity-independent (PI) across all electrode combinations (see Fig.12, element a). There were significant differences between the different polarity conditions (Kruskal-Wallis rank sum test, p < 0.001). Post hoc analysis revealed statistically significant differences between PI trials and the polarity-dependent condition (Dunn (1964) Kruskal-Wallis multiple comparisons: PI vs distal cathode, p < 0.001; PI vs proximal cathode, p = 0.029; PI vs same phalanx, p < 0.001). For polarity-dependent trials, no clear pattern existed between finger-finger and finger-palm electrode combinations. However, for the palm-palm electrode combination, the number of useful sensation trials reported was greater when the active electrode was located at the most distal electrode position (i.e., the cathodic precursor pulse was delivered to the most distal electrode in the pair). There were no significant differences between polarity-dependent conditions (Dunn Kruskal-Wallis multiple comparisons: distal cathode vs. proximal cathode, p = 0.90; distal cathode vs. same phalanx, p = 1.00; proximal cathode vs. same phalanx, p = 0.74). When looking at similarities across participants, there were no significant differences between the two conditions, with the exception of participant three (see Fig.12 ,element (b)), most participants showed little polarity dependence.,When observing the polarity dependence of the participants, the majority of these,polarity-dependent useful trials occurred when the leading pulse at the most distal electrode,position was cathodic.

[0101] Experiment 2: Effects of stimulation parameters and electrode position on distal referred sensation

[0102] In Experiment 2, a subset of electrode locations that most frequently elicited useful distal referred sensations (based on the results of Experiment 1) was examined more closely with a larger number of participants. The purpose of Experiment 2 was to characterize how the location of distal referred sensations at the index finger changed when the stimulus intensity was varied between the perceptual threshold and the maximum comfort limit.

[0103] Experiment 2: Methods

[0104] Participants and Study Visits: Twelve participants were recruited, but one participant did not complete the study. The remaining 11 participants (3 females, 8 males; age 30 ± 14 years) participated in one 3-hour experimental session followed by two 2.5-hour experimental sessions. All participants provided written informed consent to participate in these experiments, which were approved by the Metropolitan Health System Institutional Review Board. The study was conducted in accordance with the principles embodied in the Declaration of Helsinki and local statutory requirements. Sensory location was assessed for nine electrode combinations.

[0105] Selection of the nine electrode combinations: During Experiment 1, two participants reported during multiple trials that they perceived sensations near the electrode locations on the palm. These sensations were outside the index finger region, so participants were instructed to classify all trials where the sensations were located on the palm as unhelpful. Similar circumstances may have influenced the usefulness rate of the electrode combinations targeted at the palm. Assuming that return electrode size, inter-electrode distance, and distance to the underlying nerve could selectively increase stimulation thresholds with respect to return electrode size, one of the top three return electrodes was replaced with a five-centimeter electrode placed above the olecranon process (elbow electrode). The nine electrode combinations used for Experiment 2 consisted of all possible combinations between the three finger locations (IA, IL, PL) and the three non-finger locations (PA1, PP1, elbow). Electrode locations were selected based on the three most helpful finger electrodes and the three most helpful palm electrodes, with the elbow electrode replacing PA2 (see Fig.11 ).

[0106] Nine electrode combinations were evaluated: IAPA1, IL-PA1, PL-PA1, IA-PP1, IL-PP1, PL-PP1, IA-Elbow, IL-Elbow, PL-Elbow. Only one polarity orientation was investigated for each combination, where the active electrode was the most distal electrode position. This polarity was chosen because Fig.12 It is shown that most trials in Experiment 1 had no polarity dependence, and when they did, they were more likely to be reported as helpful when the distal electrode was the active electrode.

[0107] Preparation: To ensure that the electrode locations were consistent with those in Experiment 1 and were reproducible between experimental sessions, they were identified and labeled using the same procedure described in “Experiment 1: Methods”.

[0108] Parameter search: Assessment of sensory location at two different pulse widths, perception threshold and maximum comfort limit. The pulse width corresponding to the perception threshold and maximum comfort limit was recorded at five different pulse amplitudes (2, 3, 7, 15 and 30 mA).

[0109] To find the perception threshold, parameter estimation was performed using the PEST method to reduce the variability of sensory responses across participants. The PEST method consisted of starting with subthreshold stimulation and increasing the pulse width by a fixed step size in an ascending staircase until a sensation was reported, and then decreasing the pulse width in a descending staircase until the sensation disappeared. This process was repeated until five reversals were recorded. For each reversal, the step size was decreased until a 1µs step size (the minimum pulse width step size for the stimulator) was reached. The pulse width steps used for each reversal were 20, 10, 5, 2, and 1µs.

[0110] The maximum comfort limit was defined as the maximum pulse width before the sensation became uncomfortable, defined as a feeling of mild pain or physical discomfort. Furthermore, because this experiment was not intended to assess the quality or naturalness of the sensation, participants were instructed not to confuse discomfort with unnaturalness. Additionally, because some sensations may be strong but still comfortable, while others may be very weak but not uncomfortable, participants were instructed not to confuse intensity with the level of uncomfortable sensation. To find this threshold, participants used the mouse wheel to increase the pulse width by 1µs until the sensation became uncomfortable. Participants then immediately decreased the pulse width until it felt comfortable again. This process was not reversed to minimize re-exposure of participants to uncomfortable sensations.

[0111] Evaluation of sensory location: After determining the stimulus pulse width associated with the perceptual threshold and maximum comfort limit for each of the five pulse amplitudes, the pulse amplitude value with the highest dynamic range (PWmax − PWperceived) was selected for further evaluation. Because changes in thresholds were observed over short periods of time during the exploratory trials of Experiment 1, the perceptual threshold and maximum comfort limit were reassessed at the selected pulse amplitude before further experimentation. The perceptual threshold and maximum comfort limit were assessed separately using the psychometric intensity test (PIT) format (see Fig.13 , element (b) as an example). In each test, the user reported the location of the sensation by coloring the outline of the hand using up to five different colors to report up to five different intensity of the sensation.

[0112] To analyze the sensory locations reported by participants, the sensory location centroid and boundaries were calculated. Due to the discontinuity of the x-axis between fingers and the complex three-dimensionality of the fingers, 2D metrics such as centroid and boundary are not suitable for evaluating the sensory pattern on the x-axis plotted on the PIT form. Therefore, the y-axis pattern was evaluated numerically, and the x-axis pattern was evaluated visually. To analyze the pattern on the y-axis, the vertical centroid was calculated by averaging the y-axis distance of each color pixel relative to the center of the proximal phalanx (which is the most proximal active electrode location). The proximal and distal boundaries are the most distal and proximal aspects of the sensory location for each trial. Their y-axis distances are calculated in the same way as the vertical centroid. In order to give a numerical summary between different participants, the vertical centroid, proximal boundary, and distal boundary were averaged across all participants.

[0113] To assess the pattern of sensations perceived along the x-axis, PIT forms from different participants were superimposed with other participants for that same electrode combination. Superimposing all sensations regardless of reported intensity can be misleading, as sensations at the desired location may have been reported but their intensity may have been minimal, while the strongest sensations would be in the proximal region of a finger, palm, or another finger. Two superimposed outputs were created to show the pattern for all reported sensations, and only for the sensations that the participant reported as the strongest sensation during each trial.

[0114] Statistical analysis: To analyze the effect of stimulation intensity on sensory location, the various metrics used to assess sensory location (centroid, most distal sensation, most proximal sensation, and envelope size) were averaged across all participants and electrode combinations. Data were evaluated for normality using QQ plots and histograms, but did not conform to a normal distribution. Therefore, nonparametric paired difference tests (Wilcox signed-rank tests) were used to assess whether stimulation intensity affected each of the different metrics. To assess whether electrode combinations affected sensory location metrics at different stimulation intensities, nonparametric repeated measures tests (Friedmann tests) were used.

[0115] Experiment 2: Results

[0116] Sense position centroid and envelope: Fig.13 Example PIT forms reported by participant four for the IA-elbow electrode combination are shown, with different colors indicating the intensity of sensations felt in different areas. Fig.13 The element (a) shows the sensory location for the perception threshold, Fig.13 Element (b) shows the maximum comfort limit when the active electrode is located in the IA and the return electrode is located on the elbow. Purple indicates the strongest perception, and pink indicates the second strongest perception. On average, participants reported two different intensities, and the maximum number of intensities reported per trial was three. At the maximum comfort limit, the perceived sensory area changed, as shown in Fig.13 This indicates that the sensory location can be changed by changing the stimulation pulse width, and the sensory area can expand and move in the distal-proximal direction with greater stimulation intensity.

[0117] Three metrics were calculated to describe the spatial extent of the perceived sensory location. All metrics were relative to the long axis (or y-axis) of the finger. For each trial, the perceived centroid was the mean y-axis position, the distal boundary was the most distal y-axis position, and the proximal boundary was the proximal y-axis position (see Fig.15 , element a). As stimulus intensity increases from the perceptual threshold to the maximum comfort limit, the distance between the proximal and distal boundaries (called the envelope) increases (see Fig.15, element a). This perceived size increased with increasing stimulation intensity for all electrode combinations except the PL-PA1 electrode combination. In addition, four of the nine electrode combinations for participant four showed distal referred sensations, which were defined as when the segment of the sensation was located at least one phalanx away from the active electrode in the distal direction. These distal referred sensations were all located at the fingertips, between 1.5 and 2.7 phalanxes away from the active electrode. Fig.15 Elements (a) and (c) show the vertical locations of the perceptual centroid (circle), distal boundary (downward facing triangle), and proximal boundary (downward facing triangle) in units of finger phalanges from the psychometric intensity test (PIT) form. The left color (blue) indicates the percept reported at the perceptual threshold pulse width, and the right color (red) indicates the percept reported at the maximum comfort limit. The orange horizontal line marks the location of the active electrode for each electrode combination. Fig.15 Element a shows the results for participant four, Fig.15 Element (b) shows the index finger of the PIT form, which has been scaled to the axes in (a) and (c) to show the IL, IA, and PL electrode positions relative to the orange lines, and Fig.15 Element c shows the mean centroid and boundaries across participants, with standard deviations depicted by error bars (n = 11 for each electrode combination and stimulation intensity).

[0118] Across all participants, as stimulation intensity increased, for all nine electrode combinations, the center of mass shifted significantly to a more proximal location (Wilcox signed-rank test, p = 0.028), the distal border shifted significantly to a more distal location (Wilcox signed-rank test, p < 0.001), and the envelope (perceived) size increased significantly (Wilcox signed-rank test, p < 0.001) (see Fig.14 ). In addition, the electrode combination that included the elbow for the return electrode had a more proximally positioned proximal border at the maximum comfort limit. However, the mean centroid (Friedmann test, p = 0.09 for perception threshold, p = 0.71 for maximum comfort limit), distal border (Friedmann test, p = 0.05 for perception threshold, p = 0.09 for maximum comfort limit), and proximal border (Friedmann test, p = 0.09 for perception threshold, p = 0.26 for maximum comfort limit) were not statistically different among the nine electrode combinations.

[0119] Fig.14The effect of stimulation intensity across all electrodes and participants is shown. The table on the left represents the perception reported at the perception threshold pulse width, and the table on the right represents the perception reported at the maximum comfort limit. The x-axis shows different metrics comparing the effect of stimulation intensity on the location of sensations. The most distal sensation is the distance of the most distal aspect of each sensation from the center of the proximal phalanx of the index finger. The envelope size is the vertical distance between the most distal aspect and the most proximal aspect of each sensation. The vertical center of mass is also measured from the center of the proximal phalanx of the index finger. The y-axis uses the finger phalanx as the normalized distance measure. The points represent the mean across all electrode combinations and participants, and the error bars show the standard deviation (for each metric, for each stimulation intensity, n=99). Statistical significance was calculated using the Wilcoxon signed rank test. Data separated by electrode combination are shown in Figure 5. Fig.15 The element c is shown.

[0120] Assessment sensory location map:

[0121] Fig.16 The locations of sensations plotted on the PIT form at the maximum comfort limit are superimposed across participants, with redder areas (7 and 8 on the scale) indicating higher reporting frequency. The locations of sensations are shown without differentiation of the intensity level of the sensation reported within a trial. The reported sensations for all participants and electrode combinations were concentrated on the index finger (lighter colors on the index finger compared to the palm and other fingers (e.g., 3-6 on the scale). Only three of the nine combinations reported sensations on fingers other than the index finger, and these other fingers (thumb and middle finger) were positionally adjacent to the index finger. The electrode combination with the PA1 and PP1 return electrodes also tended to generate sensations that spread to the proximal area of ​​the palm. In contrast, the electrode combination with the elbow return electrode resulted in fewer participants experiencing sensations in the palm. These results are consistent with the results based on the PIT model. Fig.15 The electrode configuration shown in element c was consistent with the differences observed between the proximal borders of the vertical envelope. For each electrode combination, only one or two participants reported sensations outside the index finger region. Overall, 37% of trials (n=99) had sensations outside the target finger. The electrode combination that included the IA active electrode produced sensation locations that were roughly evenly distributed along all three phalanges of the index finger.

[0122] Fig.17 The reported locations of sensations are superimposed only for the strongest sensation reported in each trial across trials and participants. Data are shown only for trials at the maximum limit of comfort. The majority of sensations reported in all electrode combinations were centered on the index finger. Fig.15 Compared to element c, the strongest sensation reported on each trial was only on the target finger. More importantly, all electrode combinations induced distal referred sensations at the index fingertip at the strongest stimulation level on each trial.

[0123] Fig.18 It is shown which electrode combinations generated distal referred sensations for each participant at the perception threshold, maximum comfort limit, or both. At least one electrode combination successfully generated distal referred sensations for all participants at both the perception threshold and maximum comfort limit (see Fig.18 ). In addition, some participants reported distal referred sensations for most combinations tested (mean = 7.4 combinations, minimum = 2 combinations, maximum = 9 combinations). In addition, the IL-PA1 electrode combination generated distal referred perceptions for all participants for at least one of the pulse widths evaluated. When comparing active and return electrodes, only the PL electrode position reported fewer distal referred sensations than the other active electrode positions. Comparing across participants and electrode combinations, 18% of trials did not include any distal referred sensations, 4% of trials elicited distal referred sensations only at perceptual threshold, 25% of trials elicited distal referred sensations only at maximum comfort limit, and 53% of trials elicited distal referred sensations at both stimulation levels (n = 99). Thus, distal referred sensations were more common at maximum comfort limit than at perceptual threshold, although reports of distal referred sensations were by far the predominant response at both levels.

[0124] From the above description, those skilled in the art will recognize improvements, changes and modifications. Such improvements, changes and modifications are within the technical scope of those skilled in the art and are intended to be covered by the appended claims.

Claims

1. A system comprising: a controller configured to set parameters for electrical stimulation based on motion occurring in a simulated remote environment and intensity of the motion occurring in the simulated remote environment; a signal generator, coupled to the controller, configured to generate electrical stimulation including the parameters; as well as a skin surface electrode, coupled to the signal generator, configured to be placed at a first location on the user's body, the first location being away from a second location on the user's body, wherein applying the electrical stimulation having the parameters to the nerve at or near the first location on the user's body induces the second location on the user's body to experience a natural level of sensation in response to the action occurring in the simulated remote environment and the intensity of the action occurring in the simulated remote environment.

2. The system according to claim 1 further includes a plurality of skin surface electrodes, each skin surface electrode is coupled to the signal generator and is configured to be placed at a plurality of first positions on the user's body, the plurality of first positions being away from a plurality of second positions on the user's body.

3. The system according to claim 2, wherein: The controller is further configured to determine one or more skin surface electrodes among the plurality of skin surface electrodes to which the signal generator should send the electrical stimulation.

4. The system of claim 1 , further comprising an extended reality (XR) device configured to be worn by a user to display visual information related to the simulated remote environment and to communicate the intensity of the action to the controller.

5. The system according to claim 4, wherein: The XR device is a head-mounted XR device.

6. The system according to claim 1, wherein: The skin surface electrode configured to be placed at the first location on the user's body is configured to apply the electrical stimulation to a nerve associated with the sensation at the second location.

7. The system according to claim 6, wherein: The second location includes an area affected by the action in the simulated remote environment.

8. The system according to claim 6, wherein: The skin surface electrode is a portion of the glove that does not block the second location on the user's body, wherein the first location on the user's body is located on the wrist, palm, elbow, forearm and / or hand.

9. The system according to claim 1, wherein: The natural feeling level is the sensory feedback due to the electrical stimulation.

10. The system according to claim 1, wherein: The parameters are two or more of current amplitude, pulse width and frequency.

11. The system according to claim 1, wherein: The controller is further configured to change the parameter when the action or the intensity of the action changes.

12. The system of claim 1, wherein: The first location on the user's body is located near at least one sensory nerve fiber, wherein the nerve includes the at least one sensory nerve fiber.

13. A device configured to cover at least a portion of a user's wrist, palm, elbow, forearm and / or hand, the device comprising: a skin surface electrode configured to apply electrical stimulation with parameters to a nerve at or near a first location on the user's wrist, palm, elbow, forearm and / or hand to induce a second location on the user's fingertip to experience feedback responsive to the occurrence of an action and the intensity of the action in a simulated remote environment, wherein the skin surface electrode is coupled to a signal generator defining the electrical stimulation with the parameters, and the signal generator is coupled to a controller defining the parameters; and A fixing device is configured to fix the surface electrode to the wrist, palm, elbow, forearm and / or hand of the user.

14. The device according to claim 13, wherein: The device is reusable.

15. The device according to claim 13, further comprising a plurality of skin surface electrodes arranged at a plurality of first locations on the wrist, palm, elbow, forearm and / or hand of the user in a predefined electrode configuration, wherein: Each of the plurality of first locations is determined to induce feedback at one of a plurality of second locations on a fingertip of the user when the electrical stimulation is applied.

16. The apparatus according to claim 13, wherein: The device is a glove configured to not hinder a user's interaction with real objects for extended reality purposes.

17. The apparatus according to claim 13, wherein: The parameters are two or more of current amplitude, pulse width and frequency.

18. A method comprising: receiving, by a controller, an action occurring in the simulated remote environment and an intensity of the action; setting, by the controller, parameters for electrical stimulation based on the motion and the intensity of the motion; as well as The controller sends the parameters for the electrical stimulation to a signal generator, wherein the signal generator generates an electrical stimulation signal including the parameters and sends the electrical stimulation signal to skin surface electrodes to transmit the electrical stimulation signal to nerves at or near a first location on the user's body, thereby inducing a second location on the user's body to experience a sensory level in response to the action occurring in the simulated remote environment and the intensity of the action.

19. The method according to claim 18, further comprising: Displaying the simulated remote environment by an extended reality (XR) device; as well as The action and the intensity of the action are sent by the XR device to the controller.

20. The method according to claim 18, wherein: The parameters are two or more of current amplitude, pulse width and frequency.

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