Method and apparatus for motion suppression for biosignal sensing and influence

Abstract

Devices and methods for potential sensing and influence are provided. The devices of the invention include electroencephalography (EEG), electrocardiography (EKG), photoplethysmography (PPG), electromyography (EMG), and temperature devices for measuring bioactivity signals from the body. The devices are designed to include motion mitigation, hybrid non-contact and contact sensing surfaces, and optimize sensitivity under difficult sensing conditions, such as during movement through obstacles like hair and clothing, while having a convenient and small form factor. The devices of the invention provide improved sensitivity, adaptability, and noise reduction when compared to other designs. Methods for influencing the bio signals with devices having hybrid non-contact and contact sensing surfaces are also described.

Description

Technical Field

[0001] This invention relates to apparatus and methods for motion damping for sensing and influencing biosignals. More specifically, the apparatus is designed to place non-contact and / or contact sensing surfaces within an electric field or biometric field generated by a subject, and to optimize sensitivity and reduce noise under challenging sensing conditions, such as when the subject is moving and passing through obstacles like hair. The invention also relates to methods for acquiring and influencing said biosignals. Background Technology

[0002] Bioelectric sensors, such as electroencephalogram (EEG) and electrocardiogram (ECG or EKG) sensors, measure the electric fields of the brain and heart. Most commercially available EEG and ECG sensors rely on providing direct electrical contact with the skin. When the sensing location on the skin is obstructed, for example, by hair, conductive gels are often used to overcome the inadequacy of direct electrical contact. Another common approach is to use dry-brush electrodes, which penetrate between the hair and require pressure to be applied to the contact point, which can be uncomfortable or painful. A key challenge for biosensing devices is that the target signal is often contaminated by noise. Noise sources can include other bioelectric signals, such as EMG (muscle / motor neurons), noise inherent in electronics, movement of the subject and therefore the sensing surface, and external electromagnetic fields, including radio waves. More specifically, EEG signals are very small, typically ranging from 10 µV to 100 µV, and are therefore highly sensitive to noise.

[0003] Recently, non-contact potentiometric sensors have been developed. These non-contact sensors rely on capacitive coupling between the skin and the sensing plate. These sensors have successfully demonstrated non-contact sensing of EEG and ECG signals, but success in sensing through obstacles (such as hair) remains limited. In real-world obstacle scenarios, these sensors typically still suffer from interference from the aforementioned noise sources and experience poor signal quality, where the amount of obstructing material (i.e., hair) varies across multiple sensing locations, the wearer, and over time.

[0004] Non-contact sensor designs rely on flat-ridge sensing plates for capacitive coupling. Examples can be found in U.S. Patents 8,694,084, Harland 2001, Oehler 2008, Portelli 2017, Chi 2009, and Chi 2010. These non-contact sensing plates suffer from weak coupling between the electrodes and the body due to obstacles and other issues. To overcome this, the sensing plate is made larger in an attempt to increase the signal-to-noise ratio (SNR). This often involves increasing the size of the detection disk to approximately twice the diameter of a typical wet electrode (Portelli, 2017). The sensing plates shown in patent '084 incorporate an insulator, meaning they can only operate in non-contact mode.

[0005] Earlier examples of non-contact EEG and EKG sensing can be found, for example, in U.S. Patent 5,473,244, but only non-contact methods are shown, which have known drawbacks associated with signal strength and low SNR. Recently, non-contact sensing methods have been applied to the sensing of physiological states (such as drowsiness), but they have not significantly overcome the aforementioned drawbacks of non-contact devices and methods.

[0006] Influencing biometric signals from the body spans numerous disciplines and approaches, including pharmacology, therapy, meditation, breathing exercises, biofeedback, neurofeedback, and biostimulation. Neurostimulation is a form of biostimulation that involves the purposeful modulation of nervous system activity. Photobiomodulation (PBM) uses modulated near-infrared light and can be applied to stimulate the nervous system.

[0007] Precise placement of biosensors and biostimulators is crucial when sensing and influencing biosignals. Devices are typically designed to place sensors and stimulators securely against the skin or, in the case of non-contact sensors, as close as possible to the target electric field. A key challenge in sensor placement is that subjects vary in size and shape, and motion artifacts are introduced due to voluntary and involuntary movements such as breathing, blinking, swallowing, and head movements. One approach used by devices that sense EEG signals involves using a hemispinous adjustable band that wraps around the subject's head and has one or more flexible arms with sensors mounted on them, as described in U.S. Patents 8,706,182, 2017,033,2964, 2018,009,2599, 2016,031,6288, 2016. This known method generally accomplishes the task of sensor placement; however, it requires a more secure fit than this invention and is therefore less comfortable for the subject. Another drawback of this approach is that each sensor typically requires an additional arm for placement, otherwise differences in body size and shape can alter the quality of sensor placement. Furthermore, the farther the flexible arm travels from the hub or one or more main belts, the more likely the sensor will move due to the movement of the body.

[0008] Another method frequently used by EEG and EKG devices is to use a flexible wrap or cap, often made of fabric, to hold the sensor, secured by elastic or fabric strips; an example of this can be seen in U.S. Patent 9,668,694B2. A disadvantage of this method is that different head or body shapes will alter sensor pressure across different areas of the body. Furthermore, this method often requires manufacturing devices of various sizes when sensors are needed on more than one axis. Finally, these flexible caps are often secured using strips, which can introduce motion artifacts. For example, many EEG caps are secured using strips extending along the chin, where jaw movements (i.e., swallowing or speaking) will be translated into the cap and sensor, thus introducing noise into the signal.

[0009] The inventors are currently seeking to address the shortcomings of biometric sensing and influencing devices by providing a design that places sensors and stimulators in the correct positions, adapts to different body shapes and sizes, reduces signal noise from motion, provides consistent sensor pressure across multiple axes, increases user comfort, recovers from sensor displacement or movement, and increases electrical coupling between the sensing and stimulating surfaces and the target biometric field. Summary of the Invention

[0010] Therefore, the present invention relates to a wearable device comprising two or more semi-flexible bands, wherein the bands position one or more flexible diaphragms against the body for positioning, and the device may include a biosensor system and may include a biostimulation system. The present invention enables precise placement of sensors at target locations with consistent pressure across multiple axes, adapts to different body shapes and sizes, limits the effects of motion artifacts, recovers from displaced or moved sensors, and increases the electrical coupling between the sensing surface and the target electric field or other target biometric field.

[0011] Furthermore, the present invention relates to a biosensor electrode for sensing electric fields from the body, said biosensor electrode being soft, flexible, elastic, and non-planar. This sensing surface can provide capacitive coupling or direct coupling with the target electric field. Conforming the sensing surface to the shape of the body increases the sensing surface area placed within the electric field, thereby increasing the effect of capacitive coupling. The sensing surface restricts movement and recovers from displacement by utilizing its elasticity to suppress motion and fill air gaps. Furthermore, these sensors may be more comfortable and do not require excessive pressure to force the sensing surface downwards onto the body, and are not abrasive.

[0012] The present invention further relates to a method for influencing biosignals from one or more subjects. Biosignals from the body are processed, analyzed, and used to provide feedback to the subject. Analyzing the biosignals involves assessing the subject's mental, physiological, psychological, physical, and / or automatic health and / or state, and the feedback is intended to help the subject adjust or change the analyzed health and / or state. Feedback to the subject may include audio, visual, vibrational, tactile, movement or change in another object or device, or other means of sensory feedback, and further includes biostimulatory feedback, such as photobiomodulation (PBM). Other forms of feedback may include information, recommendations, diagnoses, or instructions via text, audio, or other means. Attached Figure Description

[0013] The invention will be better understood from the following detailed description of several embodiments with reference to the accompanying drawings, in which:

[0014] - Figure 1 A perspective view of an exemplary device according to an embodiment of the present invention, capable of accurately and comfortably placing biosensors and biostimulators on different head shapes and sizes, is presented.

[0015] - Figure 2 A side view of an exemplary device according to an embodiment of the present invention is shown, which enables accurate and comfortable placement of biosensors and biostimulators on different head shapes and sizes.

[0016] - Figure 3 A top view of an exemplary device according to an embodiment of the present invention is shown, which enables the accurate and comfortable placement of biosensors and biostimulators on different head shapes and sizes.

[0017] - Figure 4 A top view of an exemplary device having multiple diaphragms and another device having webbed diaphragms, according to an embodiment of the present invention, is shown.

[0018] - Figure 5 An exemplary sensor system with a soft, flexible, resilient, and non-flat sensing surface, comprising a raised feature extending from a core, is presented according to an embodiment of the invention.

[0019] - Figure 6 A sensor system according to an embodiment of the present invention is shown, which has a protective shield to prevent external electrical interference.

[0020] - Figure 7 A sensor system with a sensing surface is presented that conforms to the shape of the body when the soft, flexible, elastic and non-flat sensing surface is pressed.

[0021] - Figure 8 An alternative sensor system according to an embodiment of the invention is presented, wherein the soft, flexible, elastic and non-flat sensing surface does not have additional features extending from the core.

[0022] - Figure 9 A flowchart illustrating a sensing protocol method according to an embodiment of the present invention is presented. Detailed Implementation

[0023] This invention relates to a biosensor electrode for sensing electric fields from the body, comprising:

[0024] - A soft, flexible, resilient, and non-planar electrode core, which may include one or more features extending from its outermost surface.

[0025] - The total height of the electrode core and features must be at least 10% of the width or length of the core, whichever is greater.

[0026] - The hardness (durometer) of the electrode core and features must be less than 50 Shore A, and ideally less than 10 Shore A.

[0027] - Wherein the features extending from the surface of the electrode core must be less than 50% of the total height of the electrode.

[0028] Wherein, when the feature is pressed against both a sphere with a circumference of 55 cm and a flat surface with a force of 250 grams, the surface area of ​​the feature must account for at least 30% of the surface area of ​​the outermost surface of the electrode core.

[0029] - A sensing surface or conductive coating on the electrode core and the extended features.

[0030] - Electrical connection from the sensing surface to the amplifier.

[0031] The biosensor surface conforms to the shape of the subject's body. This sensing surface can provide capacitive or direct coupling with the target electric field. The conformation of the sensing surface to the body shape ( Figure 7 This increases the area of ​​the sensing surface placed within the electric field, thereby increasing the effect of capacitive coupling. Furthermore, the sensing surface restricts movement and recovers from displacement by utilizing its elasticity to suppress motion and fill the air gap between the surface and the body.

[0032] In one embodiment, the conductive coating is composed of a conductive fabric, which may include silver, nickel, copper, gold, graphene, and / or other conductive coatings. In another embodiment, the conductive coating may be composed of a flexible coating of graphene or a flexible silicone resin or polymer, wherein the flexible coating is embedded or coated with a conductive material such as silver, nickel, copper, gold, silver nanowires, and / or carbon nanotubes.

[0033] In one aspect, the invention includes a capacitive biosensor system utilizing a hybrid contact and non-contact sensing surface. The sensing surface in this invention is non-planar, offering numerous advantages over existing technologies, including the ability to push aside or pass through obstacles (such as hair or clothing), a reduced overall size, while maintaining increased capacitive coupling through increased surface area, the ability to be placed on the body with less pressure, and the ability to operate in both contact and non-contact modes.

[0034] In one embodiment, features extending from the electrode core may include spherical protrusions, protrusions, ridges, protruding rings, facets, or other extrusions from the surface base. Figure 5 The shape can be optimized for the application; an ideal surface balances the following:

[0035] ● Maximize the surface area close to the body, thereby increasing the capacitive effect.

[0036] ● Placing as much of the sensing surface as possible through obstacles and as close as possible to the electric field source, reducing air gaps and obstacles will increase capacitive effects.

[0037] ● By engaging in physical contact, opportunities for direct coupling can be created.

[0038] ● The comfort of the main body.

[0039] Furthermore, the overall size of the sensing surface can be adapted based on the application, where increasing the size increases the capacitive coupling capacity.

[0040] The soft, flexible, elastic, and non-flat sensing surface is pressed against the body and placed within an electric field generated by the body. The surface may be in contact with the body, partially in contact, or not in contact. The placement may be affected by constantly changing non-ideal conditions, including obstacles, hair or body debris, body oils, movement, displacement, and varying degrees of contact with the body surface. Changes in the electric field generated by the body cause changes in the potential of the sensing surface via capacitive coupling and / or direct coupling. The signal generated by the sensing surface due to changes in the body's electric field is amplified and converted into a digital signal, and transmitted via wired or wireless connections (such as Bluetooth, WiFi, cellular, or the Internet) to a computer, telephone, wearable device, server, and / or other device, where it can be processed, stored, displayed, and / or interpreted. Figure 9 ).

[0041] In another embodiment, the invention may incorporate a guard shield that restricts the pickup of electric fields from other sources. Figure 6 Various methods exist for shielding electrodes; in one technique, a shield made of a conductive material (such as copper) is driven using a signal that matches the input voltage from a capacitive sensor.

[0042] In a preferred embodiment, one or more biosensors are placed in a wearable device, such as a headset, and placed on the body.

[0043] This invention relates to a device for capturing and / or influencing biosignals from a subject, comprising:

[0044] - Two or more semi-flexible or rigid anchors.

[0045] - Two or more semi-flexible strips, each strip having two ends, at least one end being connected to at least one anchor. The semi-flexible strips follow the curvature of the body and form openings between the strips.

[0046] - One or more flexible diaphragms. Each flexible diaphragm is connected to at least two strips at at least one point.

[0047] - Each septum and anchor contains zero or more biosensors.

[0048] - Each septum and anchor contains zero or more biostimulators.

[0049] - Contains at least one or more biosensors or biostimulators.

[0050] Placing the anchors in the correct position on the body and adjusting the size of the anchors and / or bands allows the biosensors and biostimulators to be positioned within the target area of ​​the body. When in place, the flexible diaphragm stretches, bends, and conforms to the shape of the body, and is held under tension by the semi-flexible bands and anchors. Connecting the diaphragm to more than one of the bands allows the diaphragm to distribute pressure evenly along multiple axes, rather than just a single band along its extending axis. At least two anchors contact the body, thereby applying force toward the body. In an ideal embodiment, the force of the anchors is created by the elasticity of the semi-flexible bands connected to the anchors.

[0051] In one embodiment, the device includes an embedded biosensor located within a flexible diaphragm and / or anchor, wherein the sensing surface of the biosensor extends outward toward the body. In a preferred embodiment, as previously described, the embedded biosensor is a soft, flexible, resilient, and non-planar sensing surface that conforms to the body shape, thereby increasing the surface area placed within an electric field generated by the body. The acquired signal is amplified and can be transmitted to a computer, telephone, or wearable device. The signal can be displayed, stored, and / or processed.

[0052] In one embodiment, the device includes a biostimulator located within a flexible diaphragm and / or anchor, wherein the stimulation surface of the biostimulator extends outward toward the body. A preferred embodiment utilizes non-invasive photobiomodulation (PBM) stimulation. PBM therapy uses non-ionizing photon energy to create photochemical alterations within cellular structures, typically mitochondria. Other embodiments may include PEMF (pulsed electromagnetic field), tMS (transcranial magnetic stimulation), tACS (transcranial alternating current stimulation), tRNS (transcranial random noise stimulation), and tDCS (transcranial direct current stimulation).

[0053] In one embodiment, the anchor may include a known mechanism to adjust its length to increase or decrease the length of the anchor, thereby allowing the device to adapt to different body sizes. In another embodiment, the semi-flexible strip may include a known mechanism to adjust its length to increase or decrease the length of the strip, wherein the strip can be adjusted individually, thereby allowing the device to adapt to different body sizes.

[0054] In one embodiment, the anchor includes one or more hinges, allowing the device to fold into a more compact form for storage. In another embodiment, at least one strip includes one or more hinges, allowing the device to fold into a more compact form for storage.

[0055] In a preferred embodiment, the strips extend across the body in the same direction. In other embodiments, the strips may cross or connect to each other.

[0056] In a preferred embodiment, one or more diaphragms extend between the strips to bridge the opening. The diaphragms may be filled to cover areas of the body, separate strips extending across the body, mesh, webs, or other shapes. In another embodiment, the diaphragms may be made of soft, flexible rubber, silicone, flexible fabric, or another soft, flexible material. In an ideal embodiment, the diaphragms have a stiffness of less than 40 Shore A.

[0057] In one embodiment, the biosensor comprises at least one ground electrode and at least two signal acquisition electrodes, wherein at least one signal acquisition electrode is used as a reference electrode against at least one other signal electrode.

[0058] In one embodiment, the biosensor includes at least one non-contact potentiometric sensor. In another embodiment, the biosensor includes at least one contact potentiometric sensor. In still other embodiments, the biosensor includes at least one of a photoplethysmography (PPG) sensor, a functional near-infrared spectroscopy (fNIRS) sensor, and a magnetoencephalography (MEG) sensor. In another embodiment, the biosensor includes at least one conductivity sensor. In yet another embodiment, the biosensor includes at least one temperature sensor.

[0059] In one embodiment, the biosensor is configured to capture EEG signals and / or EKG or ECG signals and / or EMG (electromyography) signals. The biosensor is connected to an amplifier, one or more passive filters, an analog-to-digital converter, and optionally a wireless transmitter and receiver.

[0060] In another embodiment, the device includes at least one speaker. An iteration of this embodiment includes a speaker embedded in an anchor within the device, wherein the anchor is an embodiment of an earphone speaker. In yet another embodiment, the device is embedded within a hat or helmet. In another embodiment, the device is embedded in a virtual reality headset, an augmented reality headset, or another sensory enhancement device. In yet another embodiment, the device is used as a brain-computer interface (BCI).

[0061] In an optional embodiment, the device comprises the following:

[0062] - Two or more semi-flexible or rigid anchors,

[0063] - Two or more semi-flexible strips, each strip having two ends, wherein at least one end is connected to at least one anchor. The semi-flexible strips follow the curvature of the body and form openings between the strips.

[0064] - One or more flexible diaphragms. Each flexible diaphragm is connected to at least two strips at at least one point.

[0065] - Each septum and anchor contains zero or more biosensors.

[0066] - Each septum and anchor contains zero or more biostimulators.

[0067] - Contains at least one or more biosensors or biostimulators.

[0068] The diaphragm is composed of another known sensor placement device. In one such embodiment, the diaphragm is an EEG cap attached to the strip, and the resulting EEG cap does not require a strip around the chin or head.

[0069] This invention relates to a method for influencing biological signals from one or more subjects, the method comprising the following steps:

[0070] - Place one or more of the aforementioned devices on the body of each subject to capture and / or influence biosignals from the subject.

[0071] - Use one or more of the devices to acquire biosignals from each subject.

[0072] - Use the device to process and analyze the biosignals, or transmit the signals to another device, where they are then processed and analyzed.

[0073] - Use the analyzed signals to provide feedback to (one or more) subjects.

[0074] - Optionally, the biological signals may continue to be acquired, processed, and analyzed, and feedback may be provided to one or more subjects in the feedback loop.

[0075] The analysis of the biosignals involves assessing the subject's mental, physiological, psychological, physical, and / or automatic health and / or state, and the feedback is designed to help the subject adjust or change the analyzed health and / or state. Feedback to the subject can be provided in various forms, including audio, visual, vibrational, tactile, movement or change in another object or device, or other means of sensory stimulation, and the feedback further includes biostimulatory feedback, such as photobiomodulation (PBM). Other forms of feedback may include indicators, information, recommendations, diagnoses, or instructions via text, audio, or other means.

[0076] In one embodiment, the method for influencing biosignals involves a subject wearing the device and receiving feedback from the device, wherein no external feedback mechanism is in place. In another embodiment, the device transmits the acquired biosignals to another device (such as a computer or mobile device), where the signal is processed and feedback is provided. In yet another embodiment, the device wirelessly transmits the acquired biosignals to a server, where the signal is processed and feedback is returned via the device, computer, or other device of the present invention.

[0077] In one embodiment, more than one subject each wears a device in which the biosignals are collectively transmitted to a server for processing and analysis, and feedback is provided based on individual and group biosignals.

[0078] In another embodiment, the device processes the biological signal and transmits it to another processing device (such as a server, computer, or mobile device), where the signal is analyzed and a report is generated. The report includes information related to diagnostic and / or health indicators, and is provided to the subject or an expert in the relevant field.

[0079] Biosensors: Electronic devices or circuits capable of reading biological signals from a biometric field. Examples include EEG electrodes, pulse oximeters and ECG electrodes, glucose sensors, and temperature sensors.

[0080] Biostimulator: Electronic devices or circuits that can alter, influence, or change biological signals.

[0081] Biosignals: Signals that can be continuously monitored from the body can be electrical or non-electrical signals.

[0082] Biometric field: The region surrounding the biosignal source, where biosensors can be used to read the biosignal. In the case of electrobiosignals, this is an electric field.

[0083] Now refer to the attached diagram, Figure 1 A perspective view of an exemplary device 1 for capturing and influencing biological signals is shown. The device 1 includes two anchors 2 and two semi-flexible strips 3, which hold a flexible diaphragm 4 with embedded biosensors and / or biostimulators 5 in place.

[0084] Figure 2 This is a side view of an exemplary device 1 for capturing and influencing biological signals. The device 1 includes two anchors 2 and two semi-flexible strips 3, which hold a flexible diaphragm 4 with embedded biosensors and / or biostimulators in place.

[0085] Figure 3 This is a top view of an exemplary device 1 for capturing and influencing biological signals. The device 1 includes two anchors 2 and two semi-flexible strips 3, which hold a flexible diaphragm 4 with embedded biosensors and / or biostimulators 5 in place. Figure 4 An additional elevation view is provided for an exemplary device for capturing and influencing biological signals.

[0086] exist Figure 5 In this sensor system 100, a resilient, non-flat sensing surface 105 having a raised feature 101 extending from a core is included. The sensing surface 105 is used for contact and / or non-contact capacitive coupling with the body 5 through hair or other obstacles 10. The sensing surface 105 is connected to an amplifier 115.

[0087] Figure 6 An alternative embodiment is illustrated, in which the sensor system 200 includes a protective shield 120 surrounding a resilient, non-flat sensing surface 105 for contact and / or non-contact capacitive coupling with the body 5 through hair or other obstacles 10. The sensing surface 105 is connected to an amplifier 115.

[0088] exist Figure 7 In this embodiment, sensor system 100 includes a resilient, non-flat sensing surface 105 for contact and / or non-contact capacitive coupling with body 5 through hair or other obstacles 10. Sensing surface 105 is connected to amplifier 115. In this figure, sensing surface 105 is shown pressed against body 5 and conforming to the shape of body 5.

[0089] exist Figure 8 In this sensor system 100, there is a resilient, non-flat sensing surface 105 without any additional features extending from the core. The sensing surface 105 is used for contact and / or non-contact capacitive coupling with the body 5 through hair or other obstacles 10. The sensing surface 105 is connected to an amplifier 115.

[0090] Figure 9 A flowchart of a sensing protocol method according to an embodiment of the present invention is provided. The protocol begins at 300, where an elastic, non-flat sensing surface is placed inside the electric field of the body. In 305, the sensing surface is coupled to the electric field generated by the body and adapted to changing conditions before being amplified and converted into a digital signal at 310.

[0091] As will be understood, the examples described above and illustrated in the accompanying drawings are intended to be exemplary only. The scope is indicated by the appended claims.

Claims

1. A wearable device for sending and receiving biosignals from a user, comprising: At least two anchors; At least two semi-flexible strips, each strip having a first end and a second end, wherein at least one of the first end and the second end of each of the semi-flexible strips is connected to at least one anchor, and wherein the at least two semi-flexible strips follow the contour of a user's body such that an opening is formed between the at least two semi-flexible strips. At least one flexible diaphragm, wherein the at least one flexible diaphragm is connected to the at least two semi-flexible strips, and the at least one flexible diaphragm is configured to stretch, bend and conform to the shape of the user's body and be held under tension by the at least two semi-flexible strips and the at least two anchors, such that the at least one flexible diaphragm uniformly distributes sensor pressure on the user's body along multiple axes. At least one biosensor is disposed on the at least one flexible diaphragm or on one or more of the at least two anchors; as well as At least one biostimulator disposed on the at least one flexible diaphragm or on one or more of the at least two anchors, wherein the biostimulator provides PBM stimulation; The correct placement of the anchor and the proper adjustment of the anchor and semi-flexible strip allow the at least one biosensor and at least one biostimulator to be positioned on the target area of ​​the user's body. The at least one biosensor includes a biosensor electrode for sensing an electric field from the user's body, the biosensor electrode comprising: A flexible electrode core, which includes one or more features extending from its outermost surface; A sensing surface disposed on the flexible electrode core and the feature, wherein the sensing surface conforms to the shape of the user's body; and A connecting element that provides an electrical connection between the sensing surface and the amplifier; The total height of the feature extending from the outermost surface of the flexible electrode core is at least 10% of the area / width / length of the flexible electrode core.

2. The wearable device of claim 1, configured to place the at least one biosensor and at least one biostimulator on a target area of ​​a user's head, wherein the biosensor electrodes are adapted for use on the user's head, and wherein the sensing surface conforms to the shape of the user's head.

3. The wearable device according to claim 1 or 2, wherein the at least one biosensor is a PPG sensor, an fNIRS sensor, or a MEG sensor.

4. The wearable device according to claim 1 or 2, wherein the at least one biosensor is configured to capture EEG signals, EKG signals, ECG signals or EMG signals.

5. The wearable device according to claim 1 or 2, configured to function as a virtual reality headset, an augmented reality headset, or a brain-computer interface.

6. The wearable device according to claim 1 or 2, wherein the at least one biosensor and at least one biostimulator, along with at least one user's body, generate a closed feedback loop, wherein the user's body generates biosignals, which are captured by the biosensor, and the biostimulator influences the user's biosignals.

7. The wearable device of claim 1 or 2, wherein the sensing surface provides coupling with a target electric field of the user, the coupling consisting of capacitive coupling or direct coupling.

8. The wearable device according to claim 1 or 2, wherein the total height of the feature extending from the outermost surface is less than 50% of the height of the biosensor electrode.

9. The wearable device according to claim 1 or 2, wherein when the feature extending from the outermost surface is pressed against both a sphere with a circumference of 55 cm and a flat surface with a force of 250 g, the surface area of ​​the feature accounts for at least 30% of the surface area of ​​the outermost surface of the flexible electrode core.

10. The wearable device of claim 1 or 2, wherein the sensing surface is a conductive coating selected from the group consisting of: silver, nickel, copper, gold, graphene conductive fabric; a flexible coating of graphene, flexible silicone resin or polymer, wherein the flexible coating is embedded or coated with a conductive material, the conductive material comprising at least one of silver, nickel, copper, gold, silver nanowires and carbon nanotubes.

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