System for preventive treatment of neurosensory disorders

Abstract

The present invention relates to a system for preventive treatment of neurosensory disorders comprising a galvanic vestibular stimulation device (200) connected to an electrode holder (100) having auricular electrodes powered by electrical signals, and a piece of virtual reality equipment (10) generating real-time images of the moving images viewed through a virtual reality headset covering the user's eyes to create an immersive experience, by displaying computer-generated images simulating a 3D environment. The electrode holder (100) comprises two series of two or three electrodes arranged to be able to make contact with the right and left periauricular regions, each of said series comprising at least one upper electrode and at least one lower electrode. The system further comprises a means for synchronising the video stream and the galvanic stimulation (300), which means is connected, on the one hand, to said piece of virtual reality equipment (400) in order to receive directional information and, on the other hand, to said galvanic stimulation device (200) in order to control the generation of stimulation signals depending on said directional information.

Description

Preventive treatment system for neurosensory disorders Scope of the invention

[0001] The present invention relates to the field of preventive treatments capable of alleviating certain neurosensory disorders, in particular motion sickness, virtual reality sickness (cyber sickness), and somatogravic illusion. These are three phenomena related to the perception of movement and balance, often associated with situations where there is a conflict between the sensory signals perceived by the body and the brain.

[0002] Motion sickness (or kinetosis) is a common condition that occurs when the brain receives conflicting information from different sensory systems: the inner ear (which controls balance), the eyes (which perceive visual movement), and the body's sensory receptors (which detect movement and position). For example, when you are in a car or boat, your eyes may see slight or steady movement (such as the vehicle's interior), while your inner ear perceives more significant movement due to jolting or rolling. This conflict between sensory signals causes symptoms of motion sickness, such as nausea, dizziness, cold sweats, and sometimes vomiting.

[0003] Somatogravic illusion is a condition in which a person is unable to determine their position, orientation, or movement relative to their surroundings. This can occur in situations where visual cues are limited or absent, or when normal sensory cues are disrupted. For example, airplane or helicopter pilots may experience somatogravic illusions when flying in low-visibility conditions, such as fog or at night, which can lead them to misinterpret their position or movement, sometimes with serious consequences.

[0004] In the context of virtual reality (VR), cybersickness can occur because the brain may receive conflicting signals between what the eyes see in the virtual world and what the inner ear perceives as movement or lack thereof, potentially leading to a feeling of discomfort similar to motion sickness. Spatial disorientation can also occur in VR if the user loses their visual bearings or is exposed to unexpected movements within the virtual environment.

[0005] To reduce and prevent motion sickness and spatial disorientation, several approaches have been proposed, including vestibular rehabilitation programs consisting of specific exercises to train the vestibular system to better manage conflicting signals, thus reducing long-term symptoms.

[0006] Vestibular galvanic stimulation (VGS) is a method that uses low-intensity electrical currents applied to the mastoid processes behind the ears to stimulate the vestibular system. This type of stimulation can modulate the activity of the balance organs in the inner ear, thereby influencing the perception of balance and movement. Vestibular galvanic stimulation has been explored as a means of treating various vestibular disorders and for balance rehabilitation. State of the art

[0007] The prior art includes US patent application 2023 / 381515 A1 (Covalin et al.), which discloses a SGV + VR system with immersive visualization and galvanic signal generation. This document describes a stimulation system based on image-based orientation recognition. This device does not contain a multi-electrode structure for the upper and lower lateral electrodes, nor does it incorporate electrode / VR direction matching logic.

[0008] US patent application 2020 / 230497 describes an immersive system with 3D video recording and transmission of stimuli synchronized with the actor's movements. The stimulation is linked to body movements and not specifically to visual direction in a simulated virtual environment.

[0009] US patent 9,564,059 illustrates a multimodal stimulation device, including electrostimulation and VR. This document proposes methods for reducing sensory conflicts. Figures 8 through 11 show stimulation curves, without specific management of electrode combinations related to virtual direction. Disadvantages of prior art

[0010] Prior art solutions require a relatively complex scientific protocol, limiting their use to research purposes or with specialized guidance. Furthermore, there are several side effects associated with SVG. For example, improperly calibrated stimulation can cause postural instability if it is too strong, or an unpleasant tingling sensation at the stimulation point.

[0011] Consequently, vestibular galvanic stimulation (VGS) is rarely used in pilot training, and further research is needed to determine its efficacy and safety in this context. Current approaches to addressing spatial disorientation primarily include advanced training techniques, the use of reliable flight instruments, and sophisticated flight simulators that can recreate disorienting flight conditions for pilot training.

[0012] In particular, in patent US9564059B2, vestibular galvanic stimulation (VGS) signals are generated based on information received about movement and the stimuli needed to induce a perception of movement in the user.

[0013] The system receives input data about movement: information concerning the subject's real or simulated movement, such as orientation, speed, and direction of movement. This data can come from sensors placed on the subject or from a stimulation system (for example, a flight simulator or a video game).

[0014] The calculation of the necessary stimuli is performed by a processing module within the system to determine the level of stimulation required to generate the perception of movement corresponding to the collected movement data. This calculation takes into account the direction and intensity of the movement to be simulated so that the vestibular stimulation is consistent with the movement perceived by the user.

[0015] Electrical signals are then applied through electrodes placed on the user's head. The direction and intensity of these signals are adjusted to create a sensation of movement that corresponds to the detected or simulated movement.

[0016] The system can adjust the signals in real time based on detected changes in movement or user interactions with the simulated environment.

[0017] In this prior art solution, stimulation signals are generated based on the correspondence between the perceived movement (real or simulated) and the movement that the system wishes to induce in the user, in order to create an immersive experience or to mitigate undesirable effects such as motion sickness.

[0018] None of these previous documents manage to ensure realistic sensory coherence between visual and vestibular signals, which limits their immersive and therapeutic effectiveness, particularly in reducing sensory conflicts that generate discomfort or cybersickness. These known solutions do not achieve sufficient sensory coherence between the visual images perceived in an immersive virtual environment and the vestibular signals delivered to the user to effectively reduce VR-induced neurosensory disturbances. Object of the invention

[0019] The present invention relates to an effective and easy-to-implement solution for treating neurosensory disorders such as motion sickness, discomfort resulting from the use of virtual reality and spatial disorientation of pilots, usable with lightweight and accessible equipment without complex scientific protocol.

[0020] Vestibular galvanic stimulation can thus be used in various contexts: Training and Rehabilitation: Vestibular galvanic stimulation could be used to train pilots to better manage vestibular illusions by exposing them to electrically induced motion sensations in a controlled environment. This could improve their ability to recognize and compensate for illusions in actual flight. Research and Understanding: Vestibular galvanic stimulation can be used in research to better understand how vestibular illusions contribute to spatial disorientation. This could help develop better training techniques and preventative devices.Post-incident rehabilitation: After a spatial disorientation incident, vestibular galvanic stimulation could help pilots rehabilitate their vestibular system and restore their confidence in their sensory perception. Enhanced virtual reality immersion: By combining visual stimulation via images in the headset and real-time galvanic stimulation, it is possible to amplify the sensations and immersion in virtual reality.

[0021] To this end, the invention relates in particular to a preventive treatment system for neurosensory disorders comprising a vestibular galvanic stimulation device (200) connected to an electrode holder (100) having auricular electrodes powered by electrical signals, and a virtual reality device (10) generating real-time images of animated images viewed by a virtual reality headset that covers the user's eyes to create an immersive experience, by displaying computer-generated images that simulate a 3D environment, characterized in that said electrode holder (100) comprises two series of electrodes of two or three electrodes arranged to be able to come into contact with the right and left peri-auricular areas,And in that it further comprises a means for synchronizing the video stream and the galvanic stimulation (300) connected on the one hand to said virtual reality equipment (400) to receive directional information and on the other hand to said galvanic stimulation device (200) to control the generation of stimulation signals according to said directional information, said vestibular galvanic stimulation device (200) comprising an electronic circuit for determining the concordance between each of said directional information and the corresponding electrode combination, comprising at least one electrode powered by the active signal and at least one other electrode connected to ground.

[0022] The term "periauricular zone" refers to the cranial area surrounding the auricular cartilage, located mainly at the back of the ear, and including part of the mastoid and the lower temporal part.

[0023] Detailed description of a non-limiting example of implementation

[0024] The present invention will be better understood upon reading the following description, concerning a non-limiting example of an embodiment illustrated by the accompanying drawings where:

[0025] Figure 1 represents a schematic view of the general architecture of the system that is the subject of the invention.

[0026] This represents a schematic view of the general architecture of the system that is the object of the invention.

[0027] Lare represents a schematic view of an electrode holder device according to the invention

[0028] Lare represents a schematic view of alternative embodiments of the electrode holder device according to the invention

[0029] The figure represents a schematic view of a variant embodiment with three pairs of electrodes of the left electrode holder device, according to the invention. General principle of the invention

[0030] The invention relates to a galvanic vestibular stimulation system designed for use in virtual reality (VR) stimulation to synchronize vestibular sensory signals with visual experiences. This device uses electrodes placed on the skull to send weak electrical currents to the vestibular system, thereby altering the user's perception of movement. This helps reduce simulator sickness and spatial disorientation during immersive VR experiences.

[0031] This system is distinguished by its ability to generate signals that correspond to the directional information received from a virtual reality device. It synchronizes video feeds with galvanic stimulation to provide a more realistic and immersive experience. Unlike other devices, it incorporates a synchronization mechanism between the video feed and vestibular stimulation, ensuring consistency between what the user sees and feels in terms of movement.

[0032] In summary, the invention relates to a system that enhances VR stimulation by adjusting sensory signals to prevent neurosensory disorders, such as simulator sickness, by aligning physical sensations with virtual visual experiences.

[0033] The system according to the invention includes a means of synchronizing the video stream (generated by the virtual reality equipment) with galvanic stimulation. This means that the galvanic stimulation signals are generated based on directional information extracted from the moving images viewed by the user in the virtual reality headset. This synchronization ensures that the user experiences movement in a way that is consistent with what they see.

[0034] The various parts of the invention described below can be combined with each other. When a feature already described is repeated in the detailed presentation of the features of another aspect of the invention, this does not preclude these features from being combined with alternative features of other aspects of the invention. System architecture

[0035] The invention comprises an assembly consisting of: a stimulation electrode holder (100), preferably comprising two or three electrodes to be placed near the ear, in the mastoid area, or in the adjacent area above the auricular cartilage; a sensory stimulation device (200) which provides signals to specifically train the balance organ in a non-invasive manner; and a software application (300) for configuration and desensitization by countermeasure (emission of white noise) and by synchronization with movements and data from a virtual reality system.

[0036] This assembly interacts with a virtual reality system (10) via software connectors, and an augmented reality viewing headset (20).

[0037] The invention consists of effectively acting on balance and motor systems, as well as on sensory synchronization, for applications such as: reducing body aches and enhancing the immersive experience in virtual reality by artificially stimulating the inner ear, thus providing sensations of movement. Applications include virtual reality entertainment, pilot training to strengthen skills and improve performance, and reducing simulator aches and pains through gradual desensitization via a dedicated application.

[0038] The operation of an SDK (Software Development Kit) and the architecture of a device for VR games and stimulations according to the invention make it possible to alleviate motion sickness induced by virtual reality by applying stimulation using a device comprising miniaturized electrodes.

[0039] The objective is to prevent neurosensory disorders by ensuring coherence between visually perceived movements and vestibular signals, which is particularly relevant for immersive virtual reality stimulation, as well as for pilot training to avoid spatial disorientation phenomena or for people suffering from motion sickness to master the correlation between the movements experienced and the functioning of the inner ear. Electrode holders (100)

[0040] The electrode holder (100) has a right electrode holder and a left electrode holder.

[0041] Each electrode holder includes a means of retention adapted to a context of use, for example: An "ear loop" type piece, A flexible plastic sleeve adaptable to the arms of glasses, A VR headset attachment, A semi-rigid neckband, A headrest, And two or three electrodes per side, arranged to be applied against the skin around the ear. One of the two or three electrodes can be assigned by the sensory stimulation device (200) to the active output depending on the parameters controlled by the control application (300). Another of the two or three electrodes can be assigned by the sensory stimulation device (200) to the "ground" output depending on the parameters controlled by the control application (300).

[0042] This solution eliminates the need for a ground electrode on the nape of the neck.

[0043] The two-electrode variant is more specifically suited to combating cyber sickness and motion sickness.

[0044] The three-electrode variant is suitable for the same application and also allows for the creation of specific sensations.

[0045] The electrode holder (100) according to the invention consists of two insulating, bean-shaped cups (110, 120) provided with two or three electrodes (111, 112; 151, 152, 153; 121, 122; 161, 162, 163), intended to be placed in contact with the left and right ears to allow the application of an electrical signal for vestibular stimulation. The two pairs or triplets of electrodes (111, 112; 151, 152, 153; 121, 122; 161, 162, 163) are connected to the sensory stimulation unit (200) by an electrical cable (140).

[0046] In each pair or triplet of electrodes (111, 112; 151, 152, 153; 121, 122; 161, 162, 163), one of the electrodes corresponds to ground and at least one other to phase (active output of the sensory stimulation device (200).

[0047] The two cups (110, 120) are advantageously connected by a linking element, for example a semi-rigid neckband (130), in the shape of a hoop, positioned against the nape of the user's neck, or a headrest having two arms supporting at their end the two cups (110, 120) a flexible plastic sleeve adaptable to the arms of glasses the headband of a VR headset.

[0048] According to one option, the two cups (110, 120) are engaged in complementary connecting pieces (133, 134), provided at the ends of a connecting arch (130) or mounted on the two arms (136, 137) of an arch (135) or of a VR glasses or mask frame.

[0049] These connecting elements may also include auricular extensions (138) that completely surround the auricular cartilage to press the electrodes against the skin, or auricular extensions (139) that rest on a part of the auricular cartilage.

[0050] The cups (110, 120) are for example provided with a peripheral ring that snaps into a complementary rib provided on the complementary connecting parts, or vice versa.

[0051] Preferably, the electrodes (111, 112; 151, 152, 153; 121, 122; 161, 162, 163) are made of gold, in order to offer maximum conductivity, antimicrobial and hypoallergenic properties and have a smooth surface condition for good contact.

[0052] Variant of the execution with anteroposterior and lateral stimulation

[0053] According to this embodiment, the electrode holders (110, 120) have three electrodes around each ear, with "real-time" switching, allowing each electrode to be active, neutral, or inactive. This solution allows for a minimal and elegant "ear ring" that can be integrated with glasses.

[0054] The three electrodes (151, 152, 153; 161, 162, 163) comprise, on each side, two electrodes (151, 152; 161, 162) and one upper electrode (153, 163). The lower mastoid electrode (151, 161) is placed slightly below the mastoid area. The upper mastoid electrode (152, 162) is placed slightly above the mastoid area. The upper anterior electrode (153, 163) is placed just above the ear, in front of the mastoid electrodes.

[0055] The mastoid area is located behind the ear on a human skull. Also called the mastoid process, it is the prominent bone situated just behind the ear, an important region for electrode placement in various medical and stimulation applications.

[0056] Galvanic vestibular stimulation device (200)

[0057] The galvanic vestibular stimulation device (200) generates sinusoidal, square or stochastic electrical signals to modulate the stimulation applied by the electrodes (111, 112; 121, 122).

[0058] Stochastic Resonance will improve the perception of sensory signals and make stimulation more effective at lower intensities. Integration of the nGVS

[0059] Noisy galvanic vestibular stimulation (nGVS) uses noise signals (such as white or pink noise) to modulate electrical stimulation. These signals are integrated into the stimulation current to make the sensation more uniform and less perceptible to the skin, while increasing the effectiveness of vestibular stimulation through stochastic resonance.

[0060] Example of a piloting application (300) of the stimulation for directional sensations

[0061] The synchronization between the displacement signals from the virtual reality equipment and the signals applied to the electrodes is configured, for the three-electrode-per-side variant, as follows: Detection in the video stream of a Right / Left displacement: Right movement: apply current to the upper right electrode and use the lower left electrode as ground. Left movement: apply current to the upper left electrode and use the lower right electrode as ground. Detection in the video stream of an Up / Down displacement: Up movement: apply current to the upper electrodes (right and left) with the lower electrodes as ground. Down movement: apply current to the lower electrodes (right and left) with the upper electrodes as ground. Detection in the video stream of a Forward / Backward displacement: Forward movement: apply current to the upper anterior electrode with the mastoid electrodes.(Upper or lower) as ground. The choice of the mastoid ground electrode can modulate the intensity and perception of movement. Backward movement: apply the current to the mastoid electrodes (upper or lower) with the upper anterior electrode as ground.

[0062] Frequency and Amplitude Modulation: Modulating the frequency and amplitude of currents induces more subtle and complex sensations of movement, including forward / backward.

[0063] Cross-stimulation: Applying current between the upper left electrode and the lower right electrode (or vice versa) induces sensations of pitching or forward / backward movement.

[0064] Stimulation Modulation: To allow for a complete and complex generation of directional sensations, the intensity of the stimulation will be modulated, and consequently the level of polarization of certain nerve fibers, defined by location, type (otolithic, etc.), irregular or regular discharge afferent pathway, and / or fiber diameter. Switching System

[0065] To enable dynamic current and ground configuration, an electronic switching circuit is required. Such a circuit includes the following basic system components and operation: Microcontroller: Used to control the electrode states (active, passive, inactive) in real time; MOSFET Switching Circuit: Allows current to be directed to the desired electrode and selects which electrode serves as ground; Adjustable Current Source: Provides the necessary currents for the GVS, with controls to adjust the current intensity and frequency. Software kit features

[0066] The software library “SDK” includes computer code (15) intended for simulation software developers, for integration into the virtual reality application (10) of computer code (15) adapted to deliver the information required for the operation of the invention.

[0067] These software libraries consist of computer code capable of retrieving information from the displayed visual stream, analyzing it, transforming it into "six degrees of freedom" information and sending the information to the control application (300) controlling the galvanic vestibular stimulation device (200).

[0068] The features of the code (15) are designed to allow integration with game engines (Unity™ and Unreal Engine™), and communication with the device via a software library and to provide synchronization commands to the galvanic vestibular stimulation device.

[0069] Code (15) offers several modes for managing motion sickness or simulator sickness, including an anesthesia mode to desensitize the inner ear and a dynamic compensation mode to adjust stimulation based on in-game movements. Game developers can use these features to improve the VR user experience by reducing movement-related discomfort.

[0070] The features of the software library code (15) include: Visual Stream Acquisition and Field of View Capture. VR APIs are used to access the visual stream and head movements. Movement Analysis: Detection of rapid movements, changes of direction, and accelerations. Data Processing and Analysis: Detection of Cybersickness Risk Scenarios: Algorithms to identify conditions that may cause cybersickness, such as incoherent movements between sight and head. Data Filtering: Application of filters to smooth data and reduce noise. Interface with the device (200): Real-Time Communication: Use of Bluetooth communication protocols to send stimulation commands to the galvanic vestibular stimulation device (200). Dynamic Parameterization: Adjustment of stimulation parameters based on processed visual data.Customizing Settings: Options to customize detection thresholds and stimulation responses.

[0071] This code (15) offers an integrated solution for capturing visual flow in VR, analyzing cybersickness risks, and sending real-time stimulation commands to the galvanic vestibular stimulation device (200). This approach enhances immersion and reduces cybersickness, contributing to a more comfortable and engaging VR experience. Virtual Reality Calibration

[0072] The invention allows individualized calibration for galvanic vestibular stimulation (GVS), by implementing artificial intelligence (AI) to optimize stimulation parameters based on individual responses of the optokinetic reflex (ROK), the vestibulo-ocular reflex (RVO), and head movements captured by a virtual reality (VR) headset equipped with an eye tracker, an accelerometer, and an integrated gyroscope.

[0073] The Kinetic Opto-Optic Reflex (KOR) is a mechanism that stabilizes the visual image on the retina during prolonged movements of the visual environment. It consists of a slow tracking phase where the eyes follow a moving object and rapid saccades that return the eyes to their starting position.

[0074] In VR, an optical flow will be generated to naturally induce ROK, allowing measurement of the eye response to visual movements.

[0075] We will gradually increase the intensity of the GVS until we disrupt this reflex with inappropriate eye tracking or more frequent corrective saccades.

[0076] Disrupting this reflex provides an indication of a minimum threshold for effective stimulation.

[0077] The vestibulo-ocular reflex (VOR) stabilizes the visual image on the retina by generating eye movements opposite to head movements. This is essential for maintaining clear vision.

[0078] In VR, RVO is measured by tracking eye and head movements simultaneously. Eye-tracking cameras capture eye movements, while the integrated accelerometer and gyroscope record head movements, allowing for precise analysis of the coordination between the two.

[0079] The intensity of the GVS is gradually increased until this reflex, recorded by the eye tracker, is triggered. This will generate a head movement detected by the accelerometer, which will be the maximum threshold of effective stimulation.

[0080] AI algorithms analyze ROK, RVO, and head movement data recorded by the accelerometer and gyroscope to determine user-specific vestibular and visual responses through fine, user-specific calibration to ensure comfortable and effective stimulation, reducing visuo-vestibular conflicts. System customization

[0081] According to one variant, the invention provides for advanced calibration by artificial intelligence using ROK and RVO responses for optimal personalization in VR applications.

[0082] The terms "ROK" and "RVO" refer to specific responses in medical or physiological contexts related to balance and the vestibular system. ROK: Oculocephalic Reflex. This reflex stabilizes gaze during head movements. RVO: Vestibulo-Ocular Reflex. This reflex stabilizes images on the retina during rapid head movements by triggering compensatory eye movements in the opposite direction.

[0083] The ROK (Oculocephalic Reflex) and RVO (Vestibulo-Ocular Reflex) responses are detected by analyzing eye movements. For the ROK parameter, the discrepancy is determined between the theoretical gaze direction (the normal response is an eye movement in the opposite direction to the head movement) and the direction observed by an eye-tracking system.

[0084] The RVO parameter can be determined using Frenzel glasses or a video camera that records eye movements when the head is moved. A normal response shows compensatory eye movement to stabilize the image on the retina.

Claims

- A preventive treatment system for neurosensory disorders comprising a vestibular galvanic stimulation device (200) connected to an electrode holder (100) having auricular electrodes powered by electrical signals, and a virtual reality device (10) generating real-time animated images viewed by a virtual reality headset that covers the user's eyes to create an immersive experience, by displaying computer-generated images that simulate a 3D environment, characterized in that said electrode holder (100) has two sets of electrodes of two or three electrodes arranged to be able to come into contact with the right and left circumauricular areas,each of said series comprising at least one upper electrode and at least one lower electrode, and further comprising a means for synchronizing the video stream and the galvanic stimulation (300) connected on the one hand to said virtual reality equipment (400) to receive directional information and on the other hand to said galvanic stimulation device (200) to control the generation of stimulation signals according to said directional information, said vestibular galvanic stimulation device (200) comprising an electronic circuit for determining the correspondence between each of said directional information and the corresponding electrode combination, comprising at least one electrode powered by the active signal and at least one other electrode connected to ground. - Preventive treatment system for neurosensory disorders according to claim 1 characterized in that said electronic circuit controls: for the detection in the video stream of a lateral displacement, the supply of the upper electrode on one side by the active signal and the connection of the lower electrode on the same side to ground; for the detection in the video stream of an upward vertical displacement, the supply of the two upper electrodes by the active signal and the connection of the two lower electrodes to ground. - Preventive treatment system for neurosensory disorders according to claim 1 characterized in that said electrode holder (100) consists of two kidney-shaped, insulating cups (110, 120), each provided with two or three electrodes (111, 112; 121, 122), intended to be placed near the left and right ear, to allow the application of an electrical signal for vestibular stimulation. - Preventive treatment system for neurosensory disorders according to claim 3 characterized in that said electrode holder (100) does not include any independent ground electrode. - Preventive treatment system for neurosensory disorders according to claim 3 characterized in that said two cups (110, 120) are connected by a semi-rigid neckband (130), in the shape of a bow, positioned against the neck of the user. - Preventive treatment system for neurosensory disorders according to claim 3 characterized in that said two cups (110, 120) are integrated into a headrest having two arms supporting at their end the two cups (110, 120). - Preventive treatment system for neurosensory disorders according to claim 3 characterized in that said two cups (110, 120) are engaged in complementary connecting pieces (133, 134), provided at the ends of a connecting hoop (130) or mounted on the two arms (136, 137) of a hoop (135) or of a VR glasses or mask frame. - Preventive treatment system for neurosensory disorders according to claim 3 characterized in that each of said two cups (110, 120) has three electrodes (151, 152, 153; 161, 162, 163) positioned to support, when said electrode-carrying device is worn by a user, slightly below the mastoid area, for the lower mastoid electrode (151, 161) slightly above the mastoid area for the upper mastoid electrode (152, 162) placed above the ear, in front of the mastoid electrodes for the Upper Anterior electrode (153, 163).

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