Self-aligning eeg sensor system

Abstract

An electroencephalogram ("EEG") system, architecture, and method of measuring and monitoring subjects with generally self-aligning biosensors, EEG systems, architectures, and electrodes, to accurately measure rotational forces with easily replaceable self-aligning sensors having at least a partially encasing or enclosing an alignment or connecting member, or with a tacky material configured to adhere a self-aligning sensor or electrode to a generally flexible substrate.

Description

[0001] Non-Provisiona! Patent Application

[0002] Self-Aligning EEG Sensor System

[0003] PRIORITY

[0004] This application claims the benefit of US Provisional Patent Application No. 63 / 432,001 filed on December 12, 2022, the entirety of which is incorporated herein by reference.

[0005] FIELD

[0006] The present invention relates generally to electroencephalogram ("EEG") systems, architectures, and methods related to measuring and monitoring subjects, and, more particularly, to generally flexible biosensors, EEG systems, architectures, electrodes, and methods of use and treatment related thereto, including but not limited to methods of accurately measure rotational forces an easily replaceable sensor.

[0007] BACKGROUND OF THE INVENTION

[0008] An electroencephalograph is an electrophysiological monitoring device that is able to record electrical activity of a subject's brain. Since at least the late 1800's scientist have been recording the electrical activities of humans and animals. Electroencephalography ("EEG") typically includes a number of electrodes that are placed on a subject, typically the head, to record voltage fluctuations or changes that occur from ionic currents within the neurons of the brain.

[0009] It was quickly discovered that the voltage fluctuations of the brain had numerous applications. The applications included using the EEG as a diagnostic or clinical tool to diagnose conditions such as epilepsy, sleep disorders, state of consciousness, and even brain death. Even while advancements in medical technology moved forward, such as the invention of the MRI, the EEG's ability to monitor spontaneous changes over time, cements its importance in medicine. The electrodes of the electroencephalograph conventionally include an adhesive or paste that secures the electrode to the subject's head. Electrodes are also conventionally mounted to or coupled to a holder or substrate such as a headband or head stocking. The electrodes also typically include a connection or wire that is coupled to an electroencephalograph capable of detecting the voltage changes of the brain and displaying the results or findings on a screen for either monitoring or review by a user, such as a doctor or scientist. Findings can also be transmitted to another device for remote viewing, storing or printing.

[0010] The electroencephalograph generally consists of an electronic circuit including amplifiers and controls for processing the electrical signals received by the electrodes. The electroencephalograph also traditionally included an output device, such as an oscillograph, or more recently, a liquid crystal display, for converting the data into a readable form. All of these devices have traditionally been large, heavy, and generally required to be stationary within a room.

[0011] Various attempts have been made to provide EEG systems, architectures, and methods that can be comfortably worn by a subject either in a controlled or uncontrolled environment (e.g., out in the field). While advancements in comfortability of the electrodes and headsets worn by subject have been made, they have failed to provide EEG systems, architectures, and methods that are needed for modern times.

[0012] What is needed and what is provided by the present invention includes having EEG systems, architectures, and methods that are durable, easily repaired, more mobile and easily used by subjects in a number of settings, including but not limited to vast or remote areas where they are responsible for operation and repair of the EEG system. The present invention also provides improved clinical-grade signal quality having no te minimal motion artifacts. The present invention also provides EEG systems, architectures, and methods having electrodes that are generally conformable to an article of clothing or to a subject's anatomy. Additionally, the present invention is easily replaced, repaired, or exchanged by a subject without a loss or degradation of the signal quality collected the EEG sensor. Another advantage of the present invention is its ability to operate within a remote network that collects subject data in real-time. Yet another advantage of the present invention is its ability to collect individual subject data while in the subject is in the field and then can transmit, upload, or download the subject's data once the subject is in a secure area or location.

[0013] The above is not. intended to limit the scope of the invention, or describe each embodiment, aspect, implementation, feature, or advantage of the invention. The detailed technology and preferred embodiments for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. It is understood that the features mentioned hereinbefore and those to be commented on hereinafter may be used not only in the specified combinations, but also in other combinations or in isolation, without departing from the scope of the present invention.

[0014] SUMMARY OF THE INVEMTON

[0015] The present invention outlines example embodiments of technology and methods related to the manufacture, assembly, detection, interpretation, and response of neural activity in various environments that include, but are not limited to, being away from or remote of a clinical setting. In one example embodiment of the present invention, a user wears an apparatus, such as a headband, that is configured to hold one or more electrodes manufactured according to the method described herein. Typical EEG systems create a differential measurement between various electrodes on the head and a reference electrode, which is typically placed on the mastoid or near the ear. However, which constructed as a mobile EEG that utilizes electrodes without adhesive or clips to attach the electrode to the head, the mastoid electrodes are more susceptible to movement artifacts because of their location. Further, when a mobile EEG is constructed as a headband, the most reliable sensor locations are nearest the center of the forehead at the Fpz location.

[0016] Because EEG signals are a differential measurement to a common reference, movement or noise in the reference electrode will corrupt all channels of the EEG. Comparatively, movement or noise in one sensing electrode will just corrupt that particular channel. Similarly, a bias electrode is often used in EEG systems to provide a form of common-mode noise rejection through a feedback network. Noise on this electrode can also induce noise into all EEG signals; as such it is desired to have this make contact at a reliable electrode location.

[0017] A mobile wireless EEG headband with sensing electrodes at multiple locations, including the forehead and the mastoids, is disclosed herein. These sensing electrodes are dry, polymer- based electrodes which do not rely on gels or adhesives and require the headband to physically position these electrodes against the skin. To minimize the noise induced into the EEG signals from the motion of the wearer or from fitment of the headband, we are disclosing an alternative EEG configuration that places both the reference and bias electrodes in the most reliable location on the center of the forehead. This configuration utilizes two vertical electrodes at the center of the forehead as the bias and reference the other sensing electrodes, positioned horizontally along the forehead, as shown in Figures 1&2. Note that additional electrodes may be incorporated into the headband at the mastoid location or near the ears.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the accompanying drawings:

[0020] FIG. 1 is a functional diagram of the self-aligning sensor system in accordance with the embodiments of the invention.

[0021] FIG. 2 is a perspective view of the self-aligning sensor system connected to a headband in accordance with the embodiments of the invention.

[0022] FIG. 3A is a perspective view of a self-aligning sensor coated in accordance with the embodiments of the invention.

[0023] FIG. 3B is a top view of a self-aligning sensor coated in accordance with the embodiments of the invention.

[0024] FIG. 3C is a bottom view of a self-aligning sensor coated in accordance with the embodiments of the invention.

[0025] FIGS. 4A-4B are side elevation views of a self-aligning sensor assembled with a substrate in accordance with the embodiments of the present invention. FIGS. 5 is an exploded views illustrating the coupling or uncoupling of a self-aligning sensor with a substrate in accordance with the embodiments of the invention.

[0026] FIGS. 6 is an exploded views illustrating the coupling or uncoupling of a self-aligning sensor with a substrate in accordance with the embodiments of the invention.

[0027] FIG. 7A is an example sensor according to an example embodiment of the invention.

[0028] FIG. 78 is an example sensor with over-molding according to an example embodiment of the invention.

[0029] FIG. 7C is a cross section view of a sensor with over-molding according to an example embodiment of the invention.

[0030] FIG. 7D is an example sensor with tail according to an example embodiment of the invention.

[0031] FIGS. 8A-8B are diagrams of a user's head and a headset according to example embodiments of the invention.

[0032] FIGS. 8C-8D are diagrams of a headset and associated impact forces thereon, according to example embodiments of the invention.

[0033] FIG. 9 is diagram illustrating rotational forces.

[0034] FIG. 10 is a diagram illustrating a head, neck, and rotation axis of a user.

[0035] FIG. 11A is an example sensor according to an example embodiment of the invention.

[0036] FIG. 118 is an example sensor with a tacky fixing member according to an example embodiment of the invention.

[0037] FIG. 11C is a cross section view of a sensor with a tacky over-molding according to an example embodiment of the invention.

[0038] FIG. 12A is a perspective view of an electrode manufacturing mold according to an example embodiment of the invention.

[0039] FIG. 12B is a perspective view of an electrode array on a substrate prior to combining with a headset.

[0040] FIG. 13A is a perspective view of a sensor array of electrodes connected together by a connector. FIG. 13B is a perspective view of a sensor array of coated electrodes connected together by a connector.

[0041] FIG. 14A is a perspective view of a top of a sensor array of electrodes connected together by a connector and partially covered in a tacky fixing member.

[0042] FIG. 14B is a perspective view of a bottom of a sensor array of electrodes connected together by a connector and partially covered in a tacky fixing member.

[0043] While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular example embodiments described. On the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

[0044] DETAILED DESCRIPTION

[0045] In the following descriptions, the present invention will be explained with reference to various exemplary embodiments. Nevertheless, these embodiments are not intended to limit the present invention to any specific example, environment, application, or particular implementation described herein. Therefore, descriptions of these example embodiments are only provided for purpose of illustration rather than to limit the present invention.

[0046] Dimensions and relative proportions of components are merely example embodiments and can be varied unless specifically limited in each claim. Thus, the dimensions can be varied without departing from the scope of the invention.

[0047] The present invention illustrates devices, systems, and methods for manufacturing, repairing and using, one or more sensors (e.g., a sensor array) that are used as part of a system for monitoring, analyzing, and reporting neural activity by detecting, collecting, and analyzing electroencephalogram ("EEG”) readings from individuals or groups of individuals for a number of purposes that are examined herein. The present invention can use monitored EEG readings alone or in combination with non-EEG data from other sources, including but not limited to, user anatomical data such as vital signs (e.g., blood pressure, body temperature, pulse rate, respiration rate, heart rhythm), and anatomical changes, (e.g., eye movement, muscle twitches, facial movement, perspiration). Other non-EEG data that can be used includes environmental stimuli (e.g., photos, movies, commercials or ads, concerts, large gatherings, or police and military encounters). The present invention can collect any observable stimuli, combine it with collected EEG data, analyze it, and provide an output that can be used by users, clinicians, marketing companies, companies with employees, and the military and police.

[0048] In its simplest form, the self-aligning sensor system 10 of the present invention comprises different components or parts. As illustrated in Figures 1, the system 10 comprises at least one EEG electrode support or applicator 12, such as a headband head accessory that is securable to or about a user's head A. The EEG electrode support 12 can take any form, including but not limited to a soft headband, a helmet, or a clip. The EEG electrode support 12 may comprise any material or combination of materials. For instance, a foam or rubber material may be used alone or in combination with a generally more rigid shell.

[0049] The EEG electrode support, applicator, or assembly 12 comprises one or more self- aligning sensors or sensor assemblies 14 that are capable of reading at least EEG signals. The self- aligning sensors 14 are generally spaced apart along an inner or first surface 16 of a substrate 18 that can be flexible or rigid depending upon the particular needs of the user. In some example embodiments, substrate 18 comprises a flexible film having one or more contact or conductive tracers 20 extending from one or more sensor mounting locations 22 to a controller 30 such as a mobile phone, computer, or other transmitter / receiver. As particularly illustrated in FIG. 2, self- aligning sensors 14 can be positioned proximate to a user's mastoid bones with other self-aligning sensors 14 positioned against a user's forehead. Placement location of the self-aligning sensors 14 is only limited by the needs of the part of the user's brain needing to be monitored.

[0050] An example construction of the self-aligning sensors 14 are illustrated in FIGS. 3A-3C. In this construction example, self-aligning sensors 14 comprise at least one electrode 32 (illustrated as dashed lines) configured to receive and transmit at least bio-signals from a user’s brain. The electrodes 32 generally have a first surface 35 and a second opposed surface 36 that are connected together by a side or peripheral surface 37. The electrodes 32 generally have a puck shape or configuration but any shape may be used. The electrodes 32 generally comprise an EEG plate or any other material capable of detecting bio signals.

[0051] As particularly illustrated in FIGS. 3A-3C, self-aligning sensors 14 can be partially coated in a coating material or layer 40 that is able to contact a user's skin. Coating layer 40 may comprise a conductive material to aid in transmitting bio signals to electrodes 32 and conductive traces 20. Coating layer 40 may comprise an EEG conductive material such as a layer of silver, graphite, or a composition of a conductive material (e.g., silver nanowires) embedded in a Polydimethylsiloxane ("PDMS!I) or other carrier material.

[0052] Self-alignment of self-aligning sensors 14 is accomplished, at least in part, by one or more openings or bores 42 formed a distance into them. In one example embodiment, opening or bore 42 is formed during the molding or forming process of electrode 32. Electrode 32 may be formed about a mold that includes post that electrode 32 forms around, thereby creating opening or bore 32. Opening or bore 32 can also be added after the curing process by a material removing process (e.g., drilling or cutting). Opening or bores 42 are generally formed along or about a central axis of electrodes 32. Coating layer 40 can be applied to electrodes 32 after they are cured.

[0053] In one example embodiment of the invention, openings or bores 42 are formed on first surface 35 and / or second surface 36 of electrodes 32. Having openings or bores 42 formed on surfaces 35 and 36, allows self-aligning sensors 14 to be coupled to substrate 18 in either orientation. This has the potential of permitting a user to flip or reverse a self-aligning sensor 14 if one of the surfaces 35 or 36 becomes defective. This is particularly important in the field where replacements may not be available.

[0054] Connection of self-aligning sensors 14 and substrate 18 may be accomplished in a number of ways depending upon the configuration. For example, in one embodiment, a fastener (e.g., male and female snaps, post and sockets, slide and grooves, etc.) may be coupled to a portion of self-aligning sensors 14 and substrate 18. Some embodiments, include placement of a portion of the fastener in openings or bores 42 (e.g., a female portion of a snap) that is able to mate with another snap portion (e.g.., male portion) on substrate 18. In another example embodiment, a post member may be coupled or attached to substrate 18 and has a size and shape that is able to mate with openings or bores 52 of self-aligning sensors 14. Openings or bores 42 are molded to have a shape that is able to retain the post or male portion of fastener until they are separated by a user.

[0055] As will be discussed in more detail below, the present invention also includes a novel self- alignment arrangement using magnets to improve alignment of electrode 32 on substrate 18. This particular arrangement also has the added benefit of reducing degradation of EEG signals. Additionally, use of magnets introduces polarities that can be used to ensure an error-free way of having a user connect self-aligning sensors 14 to substrate 18.

[0056] During the manufacturing process of the magnetic embodiment, openings or bores 42 are formed similar to the above process. A blocking device or material is connected to first surface 35 and / or second surface 36 of electrode 32 or self-aligning sensors 14 assembly is formed around one or more molding posts. Similar to the above described manufacturing process, coating layer 40 may be applied, and it can be added before or after removal of the blocking devices exposing openings or bores 42.

[0057] Some example embodiments of blocking devices include, silicone plugs, magnetic plugs or plates, polymer plugs or plates that can be at least temporarily adhered to surfaces 35 and 36 of self-aligning sensors 14. Blocking devices can be any size or shape depending upon the desired size and shape openings or bores 42. Additionally, this coating method ensures high signal quality and a high rejection of motion artifacts for usage in nearly any environment (e.g., sitting, walking, running, and altercations or combat).

[0058] The present invention also improves signal quality by utilization of one or more fixed or self-aligning bias-reference sensor or electrode assembly 48. Turning back to FIG. 2, bias- reference electrode or sensor assembly 48 is illustrated positioned in a central forward region of support 12. in this particular embodiment, bias-reference sensor assembly 48 comprises a bias sensor 49a and a reference sensor 49b vertically stacked together. The bias sensor 49a and the 49b sensor can be manufactured according to the processes disclosed herein. Alternatively, bias sensor 49a or reference sensor 49b may comprise one self-aligning sensor configuration and one fixed sensor configuration. By including bias-reference sensor assembly 48, received bio signals are averaged toward the location of the bias-reference sensor assembly (e.g., here the front or forehead region of a user's head). In other example embodiments, there can be more than one bias-reference sensor assembly 48 at strategic locations depending upon the region of the brain being monitored. While bias-reference sensor assembly 48 is illustrated as a vertical stack of self- aligning sensors 32, other configurations and number of sensors 14 are also contemplated herein and the foregoing examples should not be considered limiting.

[0059] The present invention also includes an embodiment having one or more mastoid sensors 15 that are used as sensing channels versus a reference channel. Mastoid sensor 15 responds as an EEG sensing channel, limiting any noise to it allowing other EEG channels to still generate high- quality data. In one example embodiment, EEG data can be mathematically re-referenced to the mastoid in post-processing, if needed, for algorithmic or comparison purposes.

[0060] By treating the mastoids as reference channels, it allows the creation of a multi-functional device (i.e., with and without mastoids) and allows the overall configuration of the electronics, referencing, and bias functions to be consistent between products and configurations. This multi-functional characteristic of the present invention enables the system to be reconfigured for different uses. This is particularly advantageous for dynamic environments such as police and military field operations or uses as it allows system 10 to be quickly changed in the field to monitor additional or different bio signals. It is also advantageous to remote healthcare service providers that are able to purchase a single multi-functional device rather than multiple different devices. This reduces the cost of healthcare while also reducing the amount of medical / technology waste.

[0061] An advantage of having the bias sensor 49a and reference sensor 49b in the center of the forehead creates a completely symmetric EEG as it relates to the left and right sides of the brain. In this manner, symmetry between the left and right lobes of the brain can be quickly and accurately measured and analyzed.

[0062] In one particular embodiment of the invention, placement of the reference sensor 49b above bias sensor 49a helps to move the reference further from the muscles of the eyes, minimizing eye blink artifacts in the EEG. By switching the bias sensor 49a and reference sensor 49b locations, the lower position of the refence transduces more eye blink signals, which can be useful for purposes of measuring the wearer's eye movement, blink rate, which can be used to determine if a wear is fatigued, has a concussion, is impaired, has an eye injury, or has sustained some other brain injury.

[0063] Some example embodiments of the present invention, include shielding added to self" aligning sensor 32. Self-aligning electrodes 32 are mounted on a flexible printed circuit board as taught in International Patent Application Nos. PCT / US22 / 50922, filed November 23, 2022, and PCT / US22 / 18210, filed February 28, 2022, both of which are incorporated herein in their entirety by reference. Shielding the backside of this board and connecting this shield to active common- mode feedback drive signal greatly reduces the impact of electrical noise in the environment. Other configurations are also contemplated that are used for mounting. For example, providing shielding behind electrodes 14 and incorporating all electrical connections in the entire headband 12 provides optimal noise rejection.

[0064] In another example embodiment, conductive cloth shielding is provided when electrodes 14 are incorporated into a soft-goods headband 12. A portion of or an entire surface of an entire headband 12 can include a conductive cloth layer 50. This conductive cloth layer 50 provides optimal electrical shielding and noise rejection when connected to an active, low impedance drive source, including a ground or common-mode feedback signal.

[0065] When fitting a headband 12 with multiple a self-aligning sensor 14, it's important to ensure that each a self-aligning sensor 14 makes contact with the head, regardless of the head curvature. This can occur circumferentially around the head or upwards from the forehead towards the top of the head. Second, for headband 12 comfort, it is important to balance the compression of any material around a self-aligning sensor 14 to a self-aligning sensor 14 material themselves such that when worn, the majority of the pressure of the headband 12 is dispersed around the headband 12 and that a self-aligning sensor 14 just make contact. This balance prevents too much pressure being borne by a self-aligning sensor 14, which can be uncomfortable, leave marks on the forehead, and in extreme situations cause heart-rate signals to be superimposed on the EEG. For best operation, a self-aligning sensor 14 need to just make contact with the skin. Maintaining this configuration can be difficult in areas of high curvature around the head. To help this configuration, each a self-aligning sensor 14 can be individually sprung such that light pressure is always present to ensure consistent contact with the head, yet the weight of the headband 12 is not carried by the headbands 12 themselves.

[0066] To ensure optimal configuration and comfort for those wearing headband 12, the example embodiments of the invention include a one or more biasing members 54 that are able to adjust a force or pressure of self-aligning sensors 14 against the wear's head. In one example embodiment, as illustrated in FIG. 2, one or more biasing members 54 are positioned on each side of a self-aligning sensor 14. Biasing members 54 may comprise a generally resilient material such as foam or rubber that is able to compress to control the force but still retain contact of a self-aligning sensor 14 against the forehead of a wearer. Biasing member 54 can also encircle about each of a self-aligning sensor 14.

[0067] In other example embodiments of the invention, biasing member 54 may comprise a spring or other biasing or spring device beneath each a self-aligning sensor 14 or beneath substrate 18.

[0068] A particularly important aspect of the present invention is the ability of the electrodes 32. to self-align with respect to substrate 18. The above incorporated international patent applications have disclosed designs of polymer electrodes that utilize a magnetic attachment. These mostly incorporate a metal backing to provide contact with a flexible printed circuit board or other type of permanent contact embedded into the EEG headband. One of the challenges of these designs is manufacturing them such that conductive material such as silver nanowires. gold, graphite, and the like are embedded appropriately into the polymer core and make contact with the metal backing.

[0069] The present design of the present invention includes an alternative design, as illustrated in FIGS. 4A and 4B, that embeds a connecting member 60 (e.g., metal disk) into the assembly of self-aligning sensors 14. Here, self-aligning sensor 14 may comprise a polymer electrode 32 and connecting member 60, which permits magnetic attachment to substrate 18 having an attachment member 62 mounted on or coupled to it. One or both of connecting member 60 and attachment member 62 may have magnetic properties, whereby they are magnetically attracted to each other. As described above self-aligning sensors 14 may include one or more openings or bores 42 that may or may not extend through to electrode 32 or connecting member 62. Opening or bore 42 may provide an area or location on a self-aligning sensor 14 that has an increased magnetic field that allows it to self-align or center on attachment member 62. It should also be understood that coating 40 may also completely cover the assembly of self-aligning sensor 14 such that there are no openings or bores 42.

[0070] The electrical conductivity may be provided by the conductive elements in polymer electrodes 32 of self-aligning sensors 14. Conductivity can also be provided by adding a coating layer 40 having a conductive material (i.e., similar to those discussed above) or may comprise a silver chloride (AgCI) ink that is bonded to the outer surface of electrode 32 or the polymer of electrode 32. Coating a standard electrode or polymer electrode 32 with AgCI ink, which is specially formulated to bond with electrode surfaces (e.g., silicone surfaces), creates an industry gold-standard Ag / AgCI electrodes. It also provides a more reliable connection from the first or front surface 35 to the second or back surface 36 of polymer electrode 32 or the self-aligning sensor 14 of the present invention.

[0071] As mentioned above, self-aligning sensors 14 can be of any shape, size, or configuration, but for purposes of this disclosure, they are illustrated and discussed as a round, puck formfactor. In this configuration, as particularly illustrated in FIGS. 3A-4B, self-aligning sensor 14 is formed from a polymer puck electrode 32 and / or connecting member 60 that can be coated with AgCI ink on some or all its side surfaces. Self-aligning sensor 14 of the present invention is different from prior electrodes in that it is assembled with connecting member 60 (e.g., metal disk) fully or partially embedded in the polymer of electrode 32,. as illustrated in FIG. 4B. In an alternative embodiment, as illustrated in FIG. 3A, connecting member 60 may be coupled to one or more surfaces of the polymer electrode and can be partially or entirely coated with the coating or layer 40 that may also have conductive properties.

[0072] As particularly illustrated in FIGS. 4A and 4B, openings or bores 42 can formed in either coating 40 (as illustrated in FIG. 4A), which can be applied in various thicknesses or the polymer of electrodes 32 (as illustrated in FIG. 4B). As shown in FIG. 4B, self-aligning sensor 14 may have a thickness that permits it to contact the contact trace 20 on substrate 18. This configuration provides two points of electrical contact between self-aligning sensor 14 and substrate 18. The first is between self-aligning sensor 14 and attachment member 60 and the second is between self-aligning sensor 14 and contract trace 20 of substrate 18. In the event of movement of self- aligning sensor 14 in the field, the two points of contact ensure a good EEG, while reducing any noise.

[0073] Figures 5 and 6 illustrate how opening or more 42 can reduce or eliminate lateral movement of self-aligning sensor 14 once connected to attachment member 62 (see FIG. 5). In particular, sides of opening or bore 43 limit lateral movement of self-aligning sensor 14. The less amount of space between sides of opening and bore 42 and attachment member 62, the less movement there will be. As illustrated in FIG. 6, while there may be an increased amount of lateral movement of self-aligning sensor 14 when coupled to attachment member 62, the magnetic properties of connecting member 60 and attachment member 62 cause self-aligning sensor 14 to realign or self-a lign itself with respect to attachment member 62. This ensures that there will be a good EEG detected and transmitted for analyzing.

[0074] Turning to FIGS. 7A-7C, self-aligning sensors 14 of the present invention, can be constructed by molding a bottom portion or half 64 of an electrode 32 (see FIG. 7A), and allowing it to partially or fully cure. Connecting member 60 can then be placed next to bottom portion 64 of electrode 32. As illustrated in FIG. 7B, over-molding 65 can be used on the bottom portion 64 of electrode 3. Note that this can be done with or without a conductive material, such as silver nanowires, gold, or graphite, embedded on the outside surfaces of electrode 32. A top portion or half 67 of electrode 32 can then be attached or stacked on bottom portion 64. As illustrated in FIG. 7C, second over-molding 68 process can be completed covering bottom portion 64 and at least a portion of top portion 67.

[0075] After the polymer of electrode 32 is cured, it can be coated in an AgCI ink that bonds to the polymer surface. This ink can then form a transduction sensing surface along the skin and also provide a low resistance conductive surface to the backside 36 of the electrode 32. Note that it may be desired to round the corners of the electrode 32, as this prevents abrupt corners and minimizes the chance of a break in the AgCI at the corners due to incomplete bonding.

[0076] Once constructed, self-aligning sensors 14 with electrode 32 is connected to a printed circuit board (flex or otherwise) or substrate IS having either a magnet on a backside of substrate 18, or a magnet as an attachment member 60 on a front side of substrate 18. The magnetic force between attachment member 62 (e.g., a magnet) and connecting member 60 (e.g., a disk in self- aligning sensors 14) holds self-aligning sensors 14, which includes electrode 32, in tight contact with the printed circuit board or substrate 18. This enables a reliable circuit pathway from the skin surface to the amplifier electronics yet allows electrode 32 or self-aligning sensor 14 to be replaced in headband 12 without manipulating any electrical connectors.

[0077] Coating all surfaces of electrode 32 with coating 40 having an AgCI ink requires a method that provides a homogenous surface coating yet also enables airflow for a consistent curing of the AgCI ink. For instance, coating all sides of electrode 32 and placing it on a hotplate to cure would is insufficient as the bottom surface would cure at a different rate than the top surface, leading to possible swelling and distortion of electrode 32. Additionally, the uncured ink on the hotplate may inadvertently bond to the plate making removal difficult.

[0078] The present invention has overcome this issue by molding electrode 32 with a tail portion 70, as illustrated in FIG.7D. Tail portion 70 is used to attach electrode 32 to a fixture for purposes of dipping into AgCI ink and subsequently uniformly curing all sides while still attached to the rack. Tail portion 70 is either cut from electrode 32 upon completion of the manufacturing process to produce a perfectly round electrode 32 or it can be left in place to serve as a handle or grasping mechanism during attachment of electrode 32 into headgear 12.

[0079] In another example embodiment of the invention, as illustrated in FIGS. 11A-11B, an electrode 32, manufactured according to an above process (e.g., shown in steps 7A-7C), may have a low durometer fixing member 90 (e.g., a silicone or other soft tacky polymer) that is used to provide an attachment mechanism for fixing dry electrodes 32 to a PCB or substrate 18. The upper surface 35, skin-contacting, and lower surface 36, PCB or substrate 18 contacting, sides of electrode 32 remain uncoated to provide the electrical path. The tacky characteristic of fixing member 90, when molded about the sides of electrode 32 have a fairly flush edge surface 94 with the PCB or substrate 18 contacting side of electrode 32 so that it makes ready contact with the PCB or substrate 18 when applied.

[0080] PDMS electrode 32 can be coated on all sides with coating 40 (e.g., silver-silver chloride, graphite, gold, etc.). As illustrated in FIG. 11C, fixing member 90 can be applied in a stepped diameter to cover a connecting member 60 having a wider diameter than electrode 32. The stepped configuration may aid in application and removal of electrode 32 from substrate 18.

[0081] As illustrated in FIG. 12A over-molding with a soft sticky fixing member 90 (e.g., with Smooth-On Ecoflex Gel2 or other similar silicones or similarly tacky materials) can be accomplished in a mold 100. The tacky characteristic of fixing member 90 allows it to be removably adhered to substrate 18. Its tackiness allows a user to easily peel electrode 32 from substrate 18. it also allows a user to easily align and stick electrode 32 on substrate 18. If a user happens to misalign electrode 32 on substrate 18 it can be easily peeled off and reapplied. Fixing member 90 can also be more of an underlayer to avoid having tackiness on the skin facing side, in one example embodiment, fixing member 90 may have a peripheral edge that extends slightly above a skin-contacting surface of electrode 32, whereby it aids in preventing movement of electrode 32 on a user's face / head (A). The fixing member 90 can be molded into a variety of shapes and sizes. In yet another example embodiment, as illustrated in FIGS. 13A-14B, self-aligning sensors 14 are manufactured as an array 101 of several self-aligning sensors 14 connected by a connector 102 extending between each of self-aligning electrodes 14. In one embodiment, array 101 can be applied to substrate 18 as an array 101 or it can be separated into individual self-aligning electrodes 14 that can then be applied to substate 18. Self-aligning sensors 14 can be dry electrodes 14 (see FIG. 13A) or they can be covered in a conductive coating 40 (see FIG. 13B, grey shading). As illustrated in FIGS. 14A and 14B, tacky fixing member 90 can be added to array 101 to enable it to stick to substrate 18. Any configurations and arrangements of self-aligning sensors 14 described herein (e.g., including magnets, snaps, coatings, conductive coatings, etc.) can also apply to array 101.

[0082] The prevalence of head injuries in contact sports continues to gain awareness as more former athletes, both amateur and professional, are suffering from the impacts of concussions and chronic traumatic encephaly (CTE). These injuries can be acute and require immediate medical attention and recovery, as in the case of concussions, or they present longer-term as early-onset dementia that is believed to be caused by an accumulation of more minor head injuries over time. Protection and detection methods have focused on limiting and measuring the amount of linear forces on the athlete's head to minimize brain movement within the skull along with subsequent injury. However, recent medical and empirical evidence suggests that measurement of linear forces to assess concussion or CTE risk does not present a complete and causal picture of brain health.

[0083] The most recent medical research has focused on the concept of injuries coming more often from rotational forces instead of linear forces. This has a physiological rationale: a linear or direct force applied to the head can cause the brain to move back and forth within the confines of the skull by approximately ±1 millimeter (mm). In contrast, the brain can move up to ±5mm on a rotational axis due to a tangential impact from a rotational force or quick turn of the head. Because of the greater movement from a rotational force, it is believed that brain injury occurs more often in athletics from rotational impacts and that these injuries occur at lower forces than from a direct head-on impact. In order to accurately detect the risk of brain injury to an athlete (or person in any other contact role), accurate rotational forces must be measured. Turning to FIG. IDA, it is known from physics, that rotational forces are defined as a body moving through an arc of angle 6 at a distance r from the rotational axis. The rotational force is the acceleration of the vector sum of the centripetal and tangential acceleration as the body rotates around the arc.

[0084] Measuring the rotational force of a point moving around a defined circle can be measured because the radius r is known and is consistent throughout the arc. However, this becomes more challenging when measuring the rotational forces of a human head. First, the rotational axis of the head is at the base of the skull where it connects to the top of the spine. Because the neck (N) and spine (S) are positioned towards the back of the head (A), the forehead (B) is further distant from the rotational axis (AX) than the rear (C) of the head (A). As a result, for a head (A) movement from side-to-side, the front (B) of the head (A) will endure the highest rotational forces and much higher than the rear or back (C) of the head (A).

[0085] Further, because of individual variation of the human head (A) relative to the size and shape, distance from the forehead (B) to the spine (S) is not predetermined. This makes it difficult to measure rotational forces from a force sensor or accelerometer placed in a mouthguard or on the top or rear of the head (A).

[0086] Further, when using a single, three axis accelerometer, rotational forces can be difficult to decouple from linear forces. This is especially true if the rotational acceleration of the head (A) is changing and the distance from the rotational axis is unknown. Using a three-axis accelerometer can help in this situation by observing centripetal and tangential acceleration components individually; however, the magnitude of the rotational forces can be difficult to measure, as centripetal and a direct linear force on the head (A) may be measured equally along the same axis. To avoid these limitations and to improve upon the measurement of rotational forces, the present invention includes an athletic headband 12 with optimal placement of sensors. Referring to FIGS. 8A-8D, an athlete's head (A) (see FIG. 8A) and an athletic headband 12 (see FIGS. 8B-8D) are shown. For measurement of maximum rotational forces, an accelerometer 80 is placed in headband 12 that is positioned proximate to the front of the forehead (B), which experiences the most rotational forces on the head (A). Note that this headband 12 can also include protective elements and other gear worn on or about a user's head (A).

[0087] Measurement of rotational forces can be further improved by placing a second accelerometer 82 on the rear of the headband 12 (see FIG. 8B). Note that these accelerometers 80 and 82 are typically multiple axis to provide x, y, and z force data. The two accelerometers 80 and 82 work in concert to discern rotational forces from direct linear forces with easier computation. Figure 8C shows an example of direct linear impact, while FIG. 8D shows rotational impacts on the head (A). In the case of the direct impact, the head (A) moves in a singular direction and both accelerometers will measure the net acceleration in the same direction.

[0088] In the case of a rotational force on the head (A), accelerometers 80 and 82 will move in different directions and the net force on the front and rear accelerometers 80 and 82, respectively will be directly opposite one another in direction. In this situation, the net vector of force in opposite directions can be used to decouple rotational from linear forces.

[0089] The active headband measurement system of the present invention can also include a calibration function upon a user initially wearing device 12. This can be controlled via a multiple calibration settings / devices, including by using a mobile device, that would help the user move their head (A) side-to-side in a prescribed motion over a certain time period. By doing such, the angular of movement of the head (A) is known, the forces on the accelerometers 80 and 82 are known, and then by using the relative acceleration values of the front and rear accelerometers 80 and 82, respectively, the location of the rotational axis between the front and rear of the head (A)can be identified.

[0090] It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

Claims

CLAIMSWhat is claimed is:

1. A self-aligning sensor system for self-aligning individual sensors on a circuitry substrate to prevent degradation of a sensor signal, the self-aligning sensor system: a substrate having a first surface and a second opposed surface, and one or more conductive traces extending along a at least a portion of a length of the substrate; an attachment member attached to the first surface of the substrate and contacting at least a portion of the one or more conductive traces; a self-aligning sensor assembly comprising; an electrode having a first surface and a second opposed surface connected by a side surface extending therebetween; a connecting member disposed proximate to the first surface or second surface of the electrode; a conductive coating covering the electrode and the first connecting member, the conductive coating having at least one opening formed on the first surface or second surface of the electrode; and wherein the at least one opening of the conductive coating has a size and shape capable of receiving a free end of the attachment member; wherein the attachment and the connecting member are magnetically attracted to each other.

2. The self-aligning sensor system of claim 1, wherein the conductive coating comprises silver nano wires or a silver-silver chloride coating in a conductive carrier.

3. The self-aligning sensor system of claim 1, wherein the attachment member is a magnet.

4. The self-aligning sensor system of claim 1, wherein the connection member is a magnet.

5. The self-aligning sensor system of claim 1, wherein the connection member and the attachment member are magnets.

6. The self-align ing sensor system of claim 1, wherein conductive coating contacts a portion of the conductive trace when coupled to the substrate.

7. The self-aligning sensor system of claim 1, wherein the attachment member comprises a conductive post extending away from the surface of the substrate.

8. The seif-aligning sensor system of claim 1, wherein the substrate comprises a flexible material.

9. The self-aligning sensor system of claim 1, wherein size and shape of the opening in the conductive coating automatically aligns the sensor on the attachment.

10. The self-aligning sensor system of claim 9, wherein the conductive coating has a thickness conducive to preventing movement of the sensor with respect to the attachment member.

11. A method of coupling one or more self-aligning sensors to a substrate, the method comprising the steps of: providing a substrate having a first surface and a second opposed surface, and one or more conductive traces extending along a length of the substrate; the substrate having an attachment member attached to the first surface of the substrate and contacting at least a portion of the one or more conductive traces; providing a self-aligning sensor assembly comprising; an electrode having a first surface and a second opposed surface connected by a side surface extending therebetween; a connecting member disposed proximate to the first surface or second surface of the electrode; a conductive coating covering the electrode and the first connecting member, the conductive coating having at least one opening formed on the first surface or second surface of the electrode; and aligning the at least one opening of the conductive coating over the attachment member which has a size and shape capable of receiving a free end of the attachment member;wherein the electrode is coupled to the attachment member by a magnetic attraction between the attachment member and the connecting member.

12. The method of claim 11, wherein the conductive coating comprises silver nano wires or a silver-silver chloride coating in a conductive carrier.

13. The method of claim 11, wherein the attachment member is a magnet.

14. The method of claim 11, wherein the connection member is a magnet.

15. The method of claim 11, wherein the connection member and the attachment member are magnets.

16. The method of claim 11, wherein the conductive coating contacts a portion of the conductive trace when coupled to the substrate.

17. The method of claim 11, wherein the attachment member comprises a conductive post extending away from the surface of the substrate.

18. The method of claim 11, wherein the substrate comprises a flexible material.

19. The method of claim 11, wherein a size and shape of the opening in the conductive coating automatically aligns the sensor on the attachment member.

20. The method of claim 11 further comprising the step of removing the self-aligning sensor by pulling on the self-aligning sensor with enough force to overcome a magnetic force between the attachment member and the connection member, wherein a new self- aligning sensor can be coupled to the connecting member.

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