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Title:
HEADCAP FOR ELECTRICAL STIMULATION AND/OR RECORDING EEG SIGNALS
Document Type and Number:
WIPO Patent Application WO/2017/200891
Kind Code:
A1
Abstract:
A headcap for delivering electrical stimulation to and/or recording electroencephalography (EEG) signals from a subject includes a base layer configured to fit over a portion of the subject's head comprising a flexible material having a plurality of holes arranged in a predetermined array, a plurality of electrodes each sized to fit through one of the plurality of holes of the base layer and having a wire extending therefrom, an electrode hub including one or more ports for receiving the wires extending from the electrodes, the electrode hub having a housing that is sized and shaped to fit around a back portion of the subject's head. No portion of the headcap extends around the chin, jaw, or throat of the subject. A cover including an electrical shielding layer may be provided such that the plurality of electrodes and the wires are positioned between the base layer and the cover.

Inventors:
RUFFINI, Giulio (277 Mason Terrace, Apt. 1Brookline, MA, 02446, US)
MITJA, Guillem (C/ramon I Cajal, 4 Cardedeu, Barcelona, Barcelona, ES)
VALLS, Ana, Maiques (277 Mason Terrace, Apt. 1Brookline, MA, 02446, US)
Application Number:
US2017/032578
Publication Date:
November 23, 2017
Filing Date:
May 15, 2017
Export Citation:
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Assignee:
NEUROELECTRICS INC. (1 Broadway, 14th FloorCambridge, MA, 02142, US)
International Classes:
A42B1/00; A42B1/24; A61B5/00; A61B5/04
Foreign References:
CN2472461Y2002-01-16
US4967038A1990-10-30
US20160022165A12016-01-28
US6708051B12004-03-16
US9320450B22016-04-26
US20020188216A12002-12-12
Attorney, Agent or Firm:
LEUNG, Richard, L. et al. (Morgan, Lewis & Bockius LLP,1701 Market Street,Philadelphia, PA ,phpatentcorrespondence, morganlewis.com, 19103, US)
Download PDF:
Claims:
What is claimed is:

1. A headcap for delivering electrical stimulation to and/or recording electroencephalography (EEG) signals from a subject comprising: a base layer sized and shaped to contact and fit over at least a portion of the subject's head, the base layer comprising a flexible material having a plurality of holes arranged in a predetermined array; a plurality of electrodes, each of the plurality of electrodes being sized to fit through one of the plurality of holes of the base layer and having a wire extending therefrom; an electrode hub attachable to the base layer including one or more ports for receiving the wires extending from the plurality of electrodes, the electrode hub comprising a housing that is sized and shaped to fit around a back portion of the subject's head, wherein no portion of the headcap is configured to extend around the chin, jaw, or throat of the subject.

2. The headcap of claim 1, wherein the base layer is configured to have a domed shape that is sized to cover at least a majority of the subject's scalp without covering the subject's face.

3. The headcap of claim 1, wherein the base layer comprises an elastic or stretchable material.

4. The headcap of claim 1, wherein the base layer provides a physical barrier between the wires extending from the plurality of electrodes and the subject's head during use.

5. The headcap of claim 1, wherein the plurality of electrodes comprises hybrid electrodes which are configured for both EEG recording and for delivering electrical stimulation.

6. The headcap of claim 5, wherein the hybrid electrodes are configured for at least one of transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS).

7. The headcap of claim 1, wherein the plurality of electrodes comprises electrodes for delivering electrical stimulation and EEG recording.

8. The headcap of claim 1, further comprising a removable battery pack configured to connect to the electrode hub via a power port located on a base of the housing.

9. The headcap of claim 1, wherein the electrode hub is configured to receive a wired connection for power and/or data communication.

10. The headcap of claim 1, wherein the housing has a curved or U-shaped configuration which is sized to extend from one ear of the subject to the other around the back of the subject's head.

11. The headcap of claim 1, wherein the housing includes a pair of openings which are configured to surround the subject's ears during use.

12. The headcap of claim 11, wherein the base layer comprises a pair of retaining rings which are configured to be received in the pair of openings and interlock with the housing.

13. The headcap of claim 12, wherein the pair of retaining rings are configured to form a reversible snap fit with the pair of openings.

14. The headcap of claim 1, wherein the electrode hub includes an adjustment mechanism that is configured to tighten or loosen the headcap over the subject's head.

15. The headcap of claim 14, wherein adjustment mechanism is configured to pull the base layer taut around the subject's head.

16. The headcap of claim 14, wherein the adjustment mechanism comprises: a rotatable knob extending from the housing; and a cord, cable, or wire connected to the rotatable knob and to the base layer.

17. The headcap of claim 16, wherein rotating the rotatable knob in a first direction applies a tension to the cord, cable, or wire to tighten the base layer around the subject's head.

18. The headcap of any of claims 1-17, further comprising a cover which is configured to fit around the base layer, the plurality of electrodes, and the wires extending from the electrodes during use.

19. The headcap of claim 18, wherein the cover includes a flexible shielding layer configured to provide electromagnetic shielding.

20. The headcap of claim 19, wherein the flexible shielding layer includes a metal-coated fabric.

21. The headcap of claim 17, wherein the cover includes a flexible outer layer.

22. The headcap of claim 19, wherein the flexible outer layer comprises an elastic or stretchable material.

A cover for a headcap to be worn on a subject's head comprising a flexible shielding layer configured to provide electromagnetic shielding; and a flexible outer layer positioned on a first side of the shielding layer.

24. The cover of claim 23, wherein the cover is substantially dome-shaped and sized and shaped to cover at least a majority of the subject's scalp.

25. The cover of claim 23, further comprising one or more fasteners configured to attach the cover to a base layer of the headcap.

26. The cover of claim 25, wherein the one or more fasteners comprises hook-and-loop fasteners positioned on a second side of the flexible shielding layer.

27. The cover of claim 23, wherein the flexible shielding layer comprises a metal-coated fabric.

28. The cover of claim 23, wherein the flexible outer layer is permanently attached to the flexible shielding layer.

29. A headcap for delivering electrical stimulation to and/or recording electroencephalography (EEG) signals from a subject comprising: a base layer sized and shaped to contact and fit over at least a portion of the subject's head, the base layer comprising a flexible material having a plurality of holes arranged in a predetermined array; a plurality of electrodes, each of the plurality of electrodes being sized to fit through one of the plurality of holes of the base layer and having a wire extending therefrom; and a cover configured to fit around the base layer, the plurality of electrodes, and the wires extending from the electrodes such that the plurality of electrodes and the wires are positioned between the base layer and the cover, wherein no portion of the headcap is configured to extend around the chin, jaw, or throat of the subject.

30. The headcap of claim 29, wherein the cover comprises a flexible shielding layer configured to provide electromagnetic shielding to the electrodes and/or the wires during use.

31. The headcap of claim 30, wherein the flexible shielding layer comprises a metal-coated fabric.

32. The headcap of claim 29, wherein the cover includes a flexible outer layer.

33. The headcap of claim 29, wherein the cover includes one or more fasteners configured to attach the cover to the base layer.

34. The headcap of any of claims 29-33, wherein the cover is separable from the base layer.

Description:
TITLE OF THE INVENTION [0001] Headcap for Electrical Stimulation and/or Recording EEG Signals

CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62/336,970 filed May 16, 2016 and entitled "Headcap for Electrical Stimulation and/or Recording EEG

Signals," which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

[0003] The present invention, according to some embodiments, relates to a headcap configured to record electroencephalography (EEG) signals from a subject. In some embodiments, the present invention relates to a headcap that is configured to send electrical stimulation (e.g., transcranial current stimulation) to a subject. In some embodiments, the present invention relates to a headcap that is configured for both transcranial electrical stimulation and recording EEG signals.

BACKGROUND OF THE INVENTION

[0004] Electroencephalography (EEG) is an electrophysiological monitoring method which is used to record the electrical activity of a subject's brain. EEG signals, which include electrical potential differences across points on the scalp resulting from electrical activity within the brain, may be recorded using a plurality of wired electrodes which are externally positioned around the scalp of the subject's head.

[0005] Current systems used to record EEG signals may face a number of drawbacks. For example, in systems with arbitrary/customizable placement of recording electrodes, the wires that connect to the electrodes can become tangled and generally cannot be placed in the same topology from session to session, resulting in variability of wire placement between sessions. Movement of the electrodes or the electrode wires, furthermore, can result in artifacts in the signals and inaccurate recordings. Wires or electrodes in contact with the subject's scalp, for instance, may shift when the subject's body moves or when facial muscle movement causes skin displacements. Many EEG systems with arbitrary/customizable placement of recording electrodes include a chin strap to hold the apparatus in place. In addition to user discomfort, this arrangement can lead to contamination from electrode artifacts caused by mouth and/or throat movements. [0006] Yet another difficulty that may be encountered with current systems is that capacitive coupling of the electrode wires or head worn device electronics and the subject's head with the environment can induce further artifacts at various regimes. Since the wires that connect to the electrodes can act as antennas, in some applications the subject must be placed in an expensive shielded room to minimize interference.

SUMMARY OF THE INVENTION

[0007] The present invention according to certain preferred embodiments provides a headcap for recording EEG signals and/or delivering electrical stimulation that can overcome drawbacks of current systems. In some embodiments, a headcap for delivering electrical stimulation to and/or recording electroencephalography (EEG) signals from a subject includes a base layer sized and shaped to contact and fit over at least a portion of the subject's head, the base layer comprising a flexible material having a plurality of holes arranged in a predetermined array. The headcap further includes a plurality of electrodes configured to detect the EEG signals from the subject, each of the plurality of electrodes being sized to fit through one of the plurality of holes of the base layer and having a wire extending therefrom. The headcap also includes an electrode hub attachable to the base layer including one or more ports for receiving the wires extending from the plurality of electrodes, the electrode hub having a housing that is sized and shaped to fit around a back portion of the subject's head. In certain preferred embodiments, no portion of the headcap is configured to extend around the chin, jaw, or throat of the subject.

[0008] In some embodiments, the base layer is configured to have a domed shape that is sized to cover at least a majority of the subject's scalp without covering the subject's face. The base layer, in some embodiments, provides a physical barrier between the wires extending from the plurality of electrodes and the subject's head during use. The base layer may be made from a flexible material, for example, neoprene. In some embodiments, the base layer may be made from an elastic or stretchable material.

[0009] In further embodiments, the plurality of electrodes may include hybrid electrodes which are configured for both EEG recording and for delivering electrical stimulation to the subject. In certain embodiments, the hybrid electrodes are configured for at least one of transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and transcranial random noise stimulation (tRNS). The electrode hub may include the electronic components used for receiving the EEG signals detected by the plurality of electrodes and/or for generating the electrical stimulation signals delivered to the subject. In some embodiments, the headcap is powered by a removable battery pack that may be connected to the electrode hub via a power port located on a base of the housing of the electrode hub. In some embodiments, the housing has a curved or U- shaped configuration which is sized to extend from one ear of the subject to the other around the back of the subject's head. In some embodiments, the housing includes a pair of openings which are configured to surround the subject's ears during use. In yet further embodiments, the base layer comprises a pair of retaining rings which are configured to be received in the pair of openings and interlock with the housing. The pair of retaining rings may be configured, for example, to form a reversible snap fit with the pair of openings.

[0010] In certain embodiments, the electrode hub includes an adjustment mechanism that is configured to tighten or loosen the headcap over the subject's head. The adjustment mechanism is preferably configured to pull the base layer taut around the subject's head. In some embodiments, the adjustment mechanism includes a rotatable knob extending from the housing, and a cord, cable, or wire connected to the rotatable knob and to the base layer. In some such embodiments, rotating the rotatable knob in a first direction applies a tension to the cord, cable, or wire to tighten the base layer around the subject's head.

[0011] The headcap, according to some embodiments, may optionally include a cover. In some embodiments, the cover is configured to fit around the base layer, the plurality of electrodes, and the wires extending from the electrodes during use. In some embodiments, the cover helps to hold the wires extending from the electrodes in place during use in order to avoid motion artifacts in the recorded EEG signals. In some embodiments, the removable cover includes a flexible shielding layer configured to provide electromagnetic shielding. The flexible shielding layer may include a metal-coated fabric, for example, silver-coated fabric. In some embodiments, the cover includes a flexible outer layer which may be constructed, for example, from natural or synthetic fabrics, plastic, silicone, latex, neoprene, or other suitable material. In some embodiments, the flexible outer layer is made from an elastic or stretchable material. In some embodiments, the cover is removably secured to the base layer (e.g., via hook and loop fasteners). In some embodiments, the cover is not configured to be separated from the base layer. [0012] In further embodiments, a headcap for delivering electrical stimulation to and/or recording electroencephalography (EEG) signals from a subject includes a base layer sized and shaped to contact and fit over at least a portion of the subject's head, the base layer comprising a flexible material having a plurality of holes arranged in a predetermined array, a plurality of electrodes, each of the plurality of electrodes being sized to fit through one of the plurality of holes of the base layer and having a wire extending therefrom, and a cover configured to fit around the base layer, the plurality of electrodes, and the wires extending from the electrodes such that the plurality of electrodes and the wires are sandwiched between the base layer and the cover. Again, in certain preferred embodiments, no portion of the headcap is configured to extend around the chin, jaw, or throat of the subject. The cover may include a flexible shielding layer configured to provide electrical shielding to the electrodes and/or the wires during use, which may be constructed from a metal-coated fabric. The cover may further include a flexible outer layer and one or more fasteners configured to attach the cover to the base layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention can be embodied in different forms and thus should not be construed as being limited to the embodiments set forth herein.

[0014] FIG. 1 is a front perspective view of a headcap positioned on a subject's head according to an embodiment of the present invention;

[0015] FIG. 2 is a left-side view of the headcap of FIG. 1;

[0016] FIG. 3 is a rear view of the headcap of FIG. 1;

[0017] FIG. 4 is an enlarged rear view of the electrode hub of the headcap of FIG. 1;

[0018] FIG. 5 is a top perspective view of the headcap of FIG. 1;

[0019] FIG. 6 is a right-side view of the headcap of FIG. 1 further provided with a cover according to an embodiment of the present invention;

[0020] FIG. 7 is a rear view of the headcap with cover of FIG. 6; [0021] FIG. 8 is a bottom perspective view of the cover of FIG. 6 separated from the headcap;

[0022] FIG. 9 is a partial cross-sectional schematic diagram of the layers of the headcap of FIG. 6 according to an embodiment of the present invention;

[0023] FIG. 10 is a partial internal view of the electrode hub of the headcap showing an arrangement of circuit boards according to an embodiment of the present invention;

[0024] FIGS. 11 and 12 are perspective views of the electrode hub of the headcap; and

[0025] FIGS. 13 and 14 are rear and side views of the headcap of FIG. 1 further showing directions of movement for an adjustment mechanism according to an embodiment of the present invention.

DETAILED DESCRIPTION

[0026] The present subject matter will now be described more fully hereinafter with reference to the accompanying Figures, in which representative embodiments are shown. The present subject matter can, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to describe and enable one of skill in the art.

[0027] Referring to the drawings in detail, wherein like reference numerals indicate like elements throughout, there is shown in FIGS. 1-7, a headcap, generally designated 100, in accordance with an exemplary embodiment of the present invention. Headcap 100, in some embodiments, is configured to record EEG signals from a subject and/or provide electrical stimulation to a subject and generally includes a base layer 102 which is sized and shaped to cover and contact a portion of the subject's head during use, a plurality of electrodes 106 for detecting the EEG signals from the subject, and an electrode hub 112 attachable to base layer 102. In the illustrated embodiments described in detail herein, the term subject refers to a human subject. However, it should be appreciated that the headcap of the present invention could also be adapted for use on non-human animal subjects (e.g., other primates, canines, felines, equines, rodents, etc.) according to other embodiments.

[0028] Referring to Fig. 1, base layer 102 in some embodiments is sized to extend from the subject's forehead and over the subject's scalp and may have a substantially domed-shaped configuration as illustrated. In some embodiments, base layer 102 is sized and shaped to cover at least a majority of the subject's scalp without covering the subject's face. In further embodiments, base layer 102 includes cutouts that are sized, shaped, and positioned to accommodate the subject's ears such that the subject's ears are not covered by base layer 102 during use. Moreover, in certain preferred embodiments, base layer 102 does not extend around the subject's chin, jaw, or throat. In some embodiments, by avoiding the use of a chinstrap or any other components configured to extend around the subject's chin, jaw, or throat, headcap 100 may reduce contamination from electrode motion artifacts due to the subject's mouth and/or throat movements, as well as increase comfort for the subject. Base layer 102 may be constructed from a soft, flexible material that is suitable for fitting over the contours of the subject's head, for example, natural or synthetic fabrics, plastic, silicone, latex, etc. In certain preferred embodiments, base layer 102 is constructed from neoprene, synthetic rubbers, stretch fabric, or materials having similar properties (e.g., elasticity). Base layer 102 may be fabricated from a single piece of material or from separate panels which are combined together (e.g., stitched, sewn, adhered) to form the desired shape.

[0029] As particularly shown in FIGS. 1-3 and 5, base layer 102 in certain embodiments includes an array of holes 104 which may be positioned at predetermined locations on base layer 102 and which are each sized to receive an electrode 106. Holes 104 are preferably configured to allow the electrode contacts of electrodes 106 to extend through base layer 102 to contact the subject's scalp during use and to hold electrodes 106 in place relative to the subject's scalp. In some embodiments, the position of holes 104 on base layer 102 corresponds to positions along the subject's scalp where it may be desirable to detect EEG signals and/or provide electrical stimulation. For example, in some embodiments, holes 104 may be arranged on base layer 102 according to the international 10- 20 system for EEG electrode placement or other higher-resolution electrode placement maps known in the art. Base layer 102, in some embodiments, includes a label for each of the holes 104 which may be, for instance, printed on base layer 102 adjacent to each of the holes 104. For example, the labels may include letters and/or numbers to identify the cranial lobe and hemisphere location to which the hole 104 corresponds during use.

[0030] Electrodes 106 may be configured as any suitable EEG electrode known in the art. In certain embodiments, electrodes 106 are hybrid electrodes which can be used for both EEG recording and for electrical stimulation, for example, transcranial current stimulation (tCS), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and/or transcranial random noise stimulation (tRNS). In other embodiments, electrodes 106 need not be hybrid electrodes. In some embodiments, electrodes 106 include separate electrodes configured for EEG recording and electrical stimulation. In some embodiments, headcap 100 includes a separate electrode 106 for each location at which it may be desirable to detect EEG signals and/or provide electrical stimulation. In some embodiments, each electrode 106 is configured to be received in a separate hole 104 of base layer 102 during use.

[0031] Each electrode 106 may be connected to electrode hub 112 via a wire 108 which is configured to transmit signals to and from the electrode hub 112. Wires 108 extend from electrodes 106 to electrode hub 112 and are positioned on an exterior side of base layer 102 such that, during use, base layer 102 provides a physical separation between wires 108 and the subject's head. In some embodiments, separating wires 108 from the subject's head may further reduce electrode motion artifacts by reducing motion of wires 108. In some embodiments, wires 108 terminate in a connector 110 which may be removably connected to electrode hub 112 via one of a plurality of ports 114 of electrode hub 112 (FIGS. 3 and 4). Ports 114 may be positioned along a top of electrode hub 112 according to some embodiments. In some embodiments, a plurality of wires 108 may terminate in a common connector 110. In another embodiment, the electrodes 106 are wirelessly coupled to the electrode hub 112.

[0032] As shown in FIG. 10, electrode hub 112 includes a housing 116 containing various electronic components 118 which are configured for recording the EEG signals received from electrodes 106 via ports 114 and/or generating stimulation signals to electrodes 106. The electronic components 118 may include, for example, memory, processors, and circuitry that are known in the art for receiving, recording, and/or processing EEG signals. In some embodiments, electronic components 118 are organized in modules attached by flexible ribbons. In some such embodiments, the modular organization can accommodate for flexing of housing 116. In further embodiments, electrode hub 112 may further be configured to include a transmitter capable of transmitting data

(e.g., EEG data) to a computer or other receiver (not shown). The transmitter may be configured for wired and/or wireless communication. In some embodiments, electrode hub 112 may be powered by an external battery pack 120 that may be removable from electrode hub 112 for recharging or replacement. Battery pack 120, in some embodiments, may be configured to connect to electrode hub 112 via a power port located on the base of housing 116 opposite of ports 114. In some such embodiments, battery pack 120 is positioned behind the head or neck of the subject during use. In other embodiments, electrode hub 112 may include an internal power source or battery. In yet other embodiments, headcap 100 can be powered by a wired connection instead of a battery. In some embodiments, electrode hub 112 is configured to receive a wired connection which can be used for power and/or data communication. In some embodiments, a wired connection may be useful for certain closed loop applications (e.g., combination of EEG and tCS protocols) that require small closed loop latencies and jitter. In some embodiments, the wired connection includes a Universal Serial Bus (USB) connection, for example, a USB 3.0 connection which can provide about 10 ┬▒ 1 ms delays from command to received EEG change. Other wired connections may also be included. In some embodiments, electrode hub 112 further includes an on/off switch or button 126 on housing 116 which is configured to turn headcap 100 on or off. While in the illustrated embodiments electrode hub 112 is particularly configured to be worn on the subject's head, it should be appreciated that electrode hub 112 could be adapted to fit other parts of the subject's body according to other embodiments. For example, in one embodiment, electrode hub 112 could be configured to be worn on the subject's chest, which may be suitable for sleep applications.

[0033] Referring to again to FIGS. 1-3, in some embodiments, electrode hub 112 may be removably attached to base layer 102 and is configured to extend around a back portion of base layer 102. In some embodiments, base layer 102 provides a physical separation between electrode hub 112 and the subject's head. With particular reference to FIGS. 1-5, 11, and 12, housing 116 of electrode hub 112, in some embodiments, is sized and shaped to wrap around the sides and back of the subject's head during use. In some embodiments, housing 116 has a curved or U-shaped configuration which is sized to extend from one ear of the subject to the other around the back of the subject's head, as particularly shown in FIGS. 1-3. In some embodiments, housing 116 is configured to fit over or around the inion of the subject's head. Inion refers to the most prominent projection of the occipital bone at the posterioinferior (lower rear) part of the subject's skull. In some embodiments, housing 116 is configured to use the inion of the subject's head for mechanical support. In some embodiments, housing 116 is made from a rigid or semi-rigid material (e.g., plastic). In some embodiments, housing 116 may be configured to flex in order to allow for fit on different subject head sizes. In some embodiments, housing 116 further includes openings 122 which are configured to surround the subject's ears during use. Openings 122 may be circular in shape and positioned at opposite ends of housing 116 such that the subject's ears are not covered by housing 116. In some embodiments, openings 122 are configured to allow for integration with additional equipment, for example, headphones, virtual reality headsets, or other audio/visual devices. Such additional equipment may be received within openings 122 or be removably secured to housing 116.

[0034] In some embodiments, housing 1 16 may be removably attached to base layer 102 to allow base layer 102 to be removed from electrode hub 112. It may be desirable, for example, to replace one base layer 102 with another base layer 102 of a different size to accommodate for different-sized subjects, or to allow cleaning of base layer 102. In some embodiments, base layer 102 is provided with a pair of retaining rings 128 which are configured to interlock with housing 116 at openings 122. Retaining rings 128, for example, may be configured to form a reversible snap fit with openings 122 of housing 116 in order to removably attach base layer 102 to housing 116. In some embodiments, retaining rings 128 may include one or more flexible lips that are configured to engage with an edge of opening 122 of housing 116. In some embodiments, retaining rings 128 are positioned on base layer 102 to surround the subject's ears during use. FIGS. 11 and 12 show rings 128 engaged with housing 116 in openings 122 with the rest of base layer 102 removed for clarity. Other types of fasteners may be used to removably attach base layer 102 to housing 116 according to additional embodiments.

[0035] Referring to FIGS. 13-14, in some embodiments, electrode hub 112 is further configured to help secure headcap 100 to the subject's head without the need or use of a chinstrap or any other components that wrap around the chin, jaw, or throat of the subject. In some embodiments, electrode hub 112 optionally includes an adjustment mechanism that is configured to tighten or loosen headcap 100 over the subject's head. In some embodiments, the adjustment mechanism is configured to pull base layer 102 taut around the subject's head. In some embodiments, the adjustment mechanism is not configured to adjust the size of electrode hub 112, but is configured to act solely on base layer 102. In other embodiments, the adjustment mechanism is configured to adjust the size of electrode hub 112.

[0036] In some embodiments, electrode hub 112 optionally includes a rotatable knob 124 extending from housing 116 which, when turned, is configured to tighten or loosen headcap 100 over the subject's head. In some such embodiments, knob 124 may be configured apply tension to one or more cords, cables, or wires which are connected to base layer 102 in order to tighten base layer 102 around the subject's head. FIGS. 13 and 14 illustrate one non-limiting example wherein turning knob 124 in a first direction (e.g., clockwise) causes a cord or wire attached to base layer 102 to cinch in the direction illustrated by the narrow arrows, causing base layer 102 to securely tighten around the subject's head. Turning knob 124 in the opposite direction (e.g., counterclockwise) would allow the cord or wire to relax and loosen base layer 102. The cord, cable, or wire may be connected to base layer 102 on either side of the subject's head by passing through an attachment fixture 130, which may be secured on base layer 102. The attachment fixture 130 may be positioned on an exterior side of base layer 102, for example, above the subject's ears, and may be configured as a loop or hook through which the cord, cable, or wire passes through. Applying tension to the cord, cable, or wire (e.g., via knob 124), in some embodiments, will apply a force to the attachment fixture 130 which in turn pulls the base layer 102 closer to the subject's head to tighten headcap 100. In some embodiments, knob 124 may be connected to a spool which winds/unwinds the cord, cable, or wire upon turning knob 124 in order to tighten/loosen headcap 100. One non-limiting example of a suitable knob system that may be adapted for use according to the present invention is shown in U.S. Patent No. 8,713,820, which is incorporated herein by reference in its entirety. In other embodiments, headcap 100 does not require a mechanism specifically configured for tightening or loosening headcap 100 over or around the subject's head. For example, base layer 102 and/or electrode hub 112 may be sized to fit snugly around the subject's head without the need for an additional tightening mechanism. It should be appreciated that in such embodiments, knob 124 and/or attachment fixture 130 need not be present.

[0037] Referring now to FIGS. 6-8, headcap 100 according to some embodiments may optionally include a cover 132 which is configured to fit around base layer 102, electrodes 106, and wires 108 during use. Cover 132 may be substantially dome-shaped according to some embodiments, and may be sized and shaped to cover at least a majority of the subject's scalp. In some embodiments, cover 132 may also fit over at least a portion of electrode hub 112. In yet further embodiments, cover 132 may be sized and shaped to fit over the subject's ears during use. Cover 132, in some embodiments, is sized to cover all of base layer 102 without covering the subject's face. In further embodiments, cover 132 does not include a chinstrap or any components which are configured to wrap around the subject's chin, jaw, or throat. In some alternative embodiments, cover 132 may include a chinstrap. Cover 132 is preferably flexible and designed to fit snugly over base layer 102, electrodes 106, during wires 108 during use according to some embodiments. In some embodiments, use of cover 132 may help retain the position of headcap 100 over or around the subject's head. In some embodiments, use of cover 132 may help reduce signal artifacts caused by movement of wires 108 by helping to maintain the position of wires 108. In some such embodiments, wires 108 may be sandwiched in place directly between base layer 102 and cover 132 such that the positions of wires 108 are held relatively fixed. Cover 132 may also help prevent electrodes 106 from detaching from holes 104 of base layer 102 according to some embodiments. Moreover, cover 132 may serve a cosmetic function in some embodiments by hiding electrodes 106 and wires 108 from view. In some embodiments, cover 132 is removable from base layer 102. In some embodiments, cover 132 may be provided with fasteners 138 which are configured to removably secure cover 132 to base layer 102 in order to further hold cover 132 in place. In some embodiments, fasteners 138 may include hook-and-loop fasteners. Other fasteners, for example, snap buttons may also be used in some embodiments. In other embodiments, cover 132 is not configured to be removable from base layer 102. In some embodiments, cover 132 may be sewn, hemmed, adhered, or otherwise permanently attached to base layer 102 with electrodes 106 integrated between the base layer 102 and cover 132. In some embodiments, electrodes 106 are integrated into base layer 102 and/or cover 132 using textile wiring. In some embodiments, cover 132 and base layer 102 may be separated from electrode hub 112 for washing.

[0038] Cover 132, in some embodiments, may be made from one or more layers of flexible material. In some embodiments, cover 132 includes a shielding layer 134 which is configured to provide electrical shielding that reduces electrical interference from the environment and/or reduces the signal noise and capacitive coupling from static charges. In some embodiments, shielding layer 134 includes a layer including one or more metals. In some embodiments, shielding layer 134 includes a layer of metal-coated fabric and/or metallic mesh. In some embodiments, shielding layer 134 may include, for example, a silver-coated fabric. One non-limiting example of a suitable material for shielding layer 134 according to some embodiments is the metal-modified fabric available under the brand name SHIELDEX®. In some embodiments, fasteners 138 are provided on one side of shielding layer 134 for attachment to base layer 102. In further embodiments, cover 132 may include a soft, flexible outer layer 136. Outer layer 136 may be constructed from the same or different materials as base layer 102 according to some embodiments. In some embodiments, outer layer 136 is made from a material which is different from the material used for shielding layer 134. In some embodiments, outer layer 136 is made from natural or synthetic fabrics, plastic, silicone, latex, neoprene, or other suitable materials. In some embodiments, outer layer 136 is made from an elastic or stretchable material. In embodiments where both outer layer 136 and shielding layer 134 are present in cover 132, the layers may be sewn, hemmed, adhered, or otherwise permanently attached together. FIG. 9 shows a partial cross-sectional view of cover including outer layer 136 and shielding layer 134 positioned over base layer 102, electrode 106 and wire 108 according to an embodiment of the present invention. In other embodiments, cover 132 includes outer layer 136 without a shielding layer 134. In further alternative embodiments, cover 132 includes shielding layer without outer layer 136.

[0039] It should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. It should also be apparent that individual elements identified herein as belonging to a particular embodiment may be included in other embodiments of the invention. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure herein, processes, machines, manufacture, composition of matter, means, methods, or steps that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention.