GB2550843A - Headgear incorporating electrical measurement apparatus - Google Patents

Abstract

A head-gear 1 (e.g. hat or cap) incorporates flexible substrate 3, which may be metal or copper-clad, and has electrical circuitry 4, 4A within or on its surface, including electrodes 5 monitoring e.g. electro-encephalography (EEG) signals. In use, the flexible circuit 3 conforms to the users head. The headwear 1 may comprise receptacles, such as pockets or pouches, which may permanently or removably retain the substrate via e.g. stitching, hooks and loops, zips or straps. Apertures 2 may then be positioned in register with electrodes 5. An anterior 12 and posterior portion 15 may be dimensioned to extend between the users nasion and inion. Together with branches 13 (possibly releasable via electrical connectors), this may allow positioning of electrodes in register with positions of the 10-20 system, and/or monitoring of the motor or visual cortex respectively. The headgear may provide a brain-computer interface (BCI) which is discrete, unobtrusive and adaptable.

Description

HEADGEAR INCORPORATING ELECTRICAL MEASUREMENT APPARATUS Field of the Invention

This invention relates to electrical measurement apparatus, particularly electrical measurement apparatus for electroencephalography (EEG).

Background to the invention

In situations were a patient is suffering from a neural disorder such as epilepsy or where there is a potential risk of a cerebrovascular accident (CVA) or any other neural disorder including sleep disorders, it is common practice for an Electroencephalogram (EEG) to be performed to monitor and record the neural activity of the patient. This helps a healthcare professional to diagnose any particular malady which the patient may be suffering from. Recent advances in technology have allowed the apparatus necessary to perform EEGs to become more portable such that patients’ neural activity can be monitored as they go about their daily life, allowing for more accurate analysis of triggers or other stimuli which impact the patient. A brain-computer interface (BCI) is an emerging neurotechnology that can provide a direct communication and control channel that does not require normal muscular movement. BCIs are aimed at providing alternative communication and control channels for those who are physically impaired due to disease or injury. BCIs are also of interest to consumers who wish to interact with technology without movement, for example, videogames. BCI technology can be used by clinical teams assessing patients following brain injury.

Whilst recent advances have allowed EEG devices to become more portable, the typical application of these leave a lot to be desired in terms of aesthetics. A typical portable EEG device comprises a head-worn harness with a number of electrodes placed thereon, the electrodes being clearly visible when worn. These electrodes are also typically permanently incorporated within the harness body, which can restrict the placement of the electrodes on a user’s head. Furthermore the electronics for such a device are typically incorporated within a housing that protrudes from the harness such that it is also highly visible when worn.

Therefore it would be desirable to provide a portable apparatus suitable for effecting EEG; which is unobtrusive when worn; is adaptable to each user’s particular requirements; and which performs accurate and reliable EEG measurements.

Summary of the Invention

Accordingly a first aspect of the present invention provides an electrical measurement apparatus as claimed in claim 1.

The apparatus may comprise headgear incorporating a flat flexible substrate comprising an electrical circuit embedded within said substrate, wherein said circuit comprises a plurality of electrodes, wherein said headgear comprises a plurality of receptacles which are coupled thereon and within which said substrate can be removably inserted, wherein said receptacles are positioned within said headgear such that the electrodes of said substrate align with motor and sensorimotor areas of a user’s head when inserted therein and wherein said headgear incorporates a plurality of apertures which extend through said receptacles, headgear and wherein said electrodes align with said apertures and extend there through such as to contact the user’s head and wherein said circuit is configured to perform an electrophysiological monitoring method upon said user.

Ideally, said flat flexible substrate is typically shaped and dimensioned to extend from the nasal bridge to the spinal column of the user.

Preferably, said flat flexible substrate comprises a central portion and one or more branches extending therefrom.

Ideally, said central portion comprises a primary end and a secondary end.

Preferably, said primary end of said central portion extends towards the nasal bridge of the user.

Ideally, said secondary end of said central portion extends towards the spinal column of the user.

Preferably, said central portion is located within said headgear at the midway point between the between in ion and nasion which corresponds to location Cz of the 10-20 locating arrangement.

Ideally, said electrodes are incorporated within said branches.

Preferably, the plurality of branches extend laterally from said flat flexible substrate.

Ideally, said flat flexible substrate comprises a metal clad substrate.

Preferably, said metal clad substrate comprises copper clad laminate.

Ideally, said flat flexible substrate incorporates one or more connectors which are configured to allow for removable coupling of one or more of said branches.

Preferably, said headgear comprises a hat.

Ideally, said hat comprises a baseball cap.

Optionally, said headgear comprises a bandana or wig or hood or turban or any other suitable article of clothing.

Ideally, said electrophysiological monitoring method comprises an electroencephalogram (EEG). Optionally, said receptacles are permanently coupled to said headgear.

Preferably, said receptacles comprise a pocket or pouch which is removably coupled to the headgear.

Ideally, plurality of receptacles coupled to said headgear correspond to the arrangement of the flat flexible substrate.

Preferably, said flat flexible substrate substantially aligns with the contours of said user’s head in-use.

From another aspect, the invention provides a brain computer interface apparatus comprising the apparatus of the first aspect of the invention.

The term headgear as used herein is intended to embrace headwear and headdress.

Other preferred features are recited in the dependent claims filed herewith.

Further advantageous aspects of the invention will be apparent to those ordinarily skilled in the art upon review of the following description of a specific embodiment and with reference to the accompanying drawings.

Brief Description of the Drawings

The invention will now be described by example with reference to the accompanying drawings in which like numerals are used to indicate like parts and in which:

Figure 1 shows a front perspective view of headgear embodying one aspect of the invention;

Figure 2 shows a plan view of the underside of the headgear showing a electrical measurement apparatus including a flat flexible substrate;

Figure 3 shows a rearview of the headgear;

Figure 4 shows a plan view of the underside of headgear with additional coupling means provided for attachment of additional receptacles;

Figure 5 shows an embodiment of a first receptacle that may be included in the headgear within which part of the flat flexible substrate may be inserted;

Figure 6 is a perspective view of a second receptacle that may be included in the headgear and within which part of the flat flexible substrate may be inserted;

Figure 7 is a schematic diagram of an embodiment of the electrical measurement apparatus comprising electrical circuitry embedded in the flat flexible substrate;

Figure 8 is an illustration showing the 10-20 system for the placement of electrodes for an EEG test; Figure 9 is an illustration of preferred electrode placement of the electrical measurement apparatus in the context of the 10-20 system;

Figure 10 is a schematic diagram of an alternative embodiment of the electrical measurement apparatus comprising a flat flexible substrate incorporating electrical circuitry;

Figure 11 is a schematic diagram of another embodiment of the electrical measurement apparatus comprising a flat flexible substrate incorporating electrical circuitry;

Figure 12 is a schematic diagram of a further embodiment of the electrical measurement apparatus comprising a flat flexible substrate incorporating electrical circuitry.

Detailed Description of the Drawings

Referring in particular to figures 1 to 7 of the drawings there is shown, generally indicated by the reference numeral 1, headgear embodying the invention. The headgear 1 incorporates a flexible circuit comprising a flat flexible substrate 3 carrying electronic circuitry 4. The headgear 1 preferably comprises an item of clothing, most conveniently a hat, into which the flexible circuit is incorporated.

In preferred embodiments the electronic circuitry is configured to perform electroencephalography (EEG), for example an EEG test. More generally, the electronic circuitry includes at least one but typically a plurality of electrical sensors, usually in the form of electrodes 5, capable of detecting electrical activity of a user’s brain and generating corresponding electrical signals. Typically, the electrodes 5 detect voltage fluctuations resulting from ionic current within the neurons of the user’s brain. In addition to the electrodes 5, the circuitry 4 includes processing circuitry 4A, which includes electrical and/or electronic circuitry for processing electrical signals generated by the electrodes 5 during use. The processing may for example comprise any one or more of the following tasks: measurement, filtering, amplification, storage (recording), transmission (e.g. wireless transmission). In preferred embodiments the processing relates to the performance of an EEG test. In any event, in preferred embodiments the substrate 3 and circuitry 4 may be said to comprise an electrical measurement apparatus.

The substrate 3 may comprise any conventional flexible substrate suitable for use with electrical circuits. The substrate 3 may comprise one or more layers of base material, the or each layer typically comprising a flexible film, usually of a polymer material e.g. polyester (PET) or polymide (PI). In cases where the substrate comprises more than one layer, the layers may be bonded together in any conventional manner. Electrically conductive material is provided on or in the base material for forming electrical circuit paths and terminals. Typically a layer of metallic foil is provided on the surface of the, or each, base layer for this purpose, and is etched to form the required circuit paths and terminals. The circuitry 4, 4A may be located on the surface of the substrate 3 and/or embedded within the substrate 3. Any electrical or electronic components (e.g. integrated circuits) included in the circuitry 4, 4A may be located on the surface of the substrate 3 and/or embedded within the substrate 3, as is convenient. In any event, the circuitry 4 is able to flex with the substrate 3. In cases where all or part of the circuitry 4 is located on the surface of the substrate 3, it is typically covered with a layer or coating of protective non-conductive material. In preferred embodiments, the substrate 3 comprises a flexible copper clad laminate however it may alternatively comprise any other suitable flexible metal-clad substrate. The substrate 3 and circuitry 4 may together be referred to as a flexible circuit, or flex circuit. The flexible circuit is substantially flat, i.e. has a low profile, but its flexibility allows it to conform to the shape of a user’s head.

In preferred embodiments in which the circuitry 4 is configured to measure a user’s neural potentials for performing an EEG test, the electrodes 5 are preferably located on the substrate 3 to match with respective EEG electrode locations defined by an EEG electrode placement system, for example the 10-20 system, as shown in figures 8 and 9. In Figures 8 and 9, the shaded electrode locations indicate the locations of the electrodes 5 in preferred embodiments.

Advantageously the flexibility of the substrate 3, including the circuitry 4, allows it to fit around a user’s head. The electrodes 5 are preferably exposed so that they may make direct contact with the user’s head, although the electrodes 5 may be covered or coated, e.g. with a gel or polymer layer, for protection and/or to improve conductivity.

The flexibility and flatness of the flexible circuit facilitates its incorporation into the headgear 1, in particular into the inside of the headgear 1 without significantly compromising the fit and comfort of the headgear 1 and providing a discreet external appearance. In preferred embodiments, the flexible circuit is carried by, preferably removably, the inside of the headgear 1, as is described in more detail hereinafter by way of example. Alternatively, the flexible circuit and headgear may be unconnected. In any event, the flexible circuit substantially conforms to the shape of the inside of the headgear, at least when the headgear is being worn, and so also conforms to the shape of the user’s head.

In preferred embodiments, the headgear 1 includes a respective aperture 2 for at least one of and preferably all of the electrodes 5. The arrangement of the apertures 2 is such that the electrodes 5 are in register with the respective aperture 2 when the flexible circuit is within the headgear. Optionally, the respective electrode 5 is releasably fastenable in the respective aperture 2. For example the periphery of the aperture 2 and the electrode 5 may comprise structures that are shaped to provide the male and female parts of a releasable fastener. Advantageously, the electrode 5 is exposed by the aperture 2 to the external environment. Alternatively, in embodiments where the apertures 2 are not present, the headgear may be provided with a respective male or female fastener part at the desired location for each electrode, the electrode including the corresponding female or male part. This arrangement would retain the electrodes in the desired location inside the headgear (with or without receptacles).

In preferred embodiments the headgear 1 comprises a hat that is preferably size-adjustable, e.g. by means of an adjustable strap or elastication, to facilitate a close fit with the user’s head and close contact between the electrodes 5 and the user’s head. In the illustrated embodiment the headgear 1 comprises a peak cap having a body 6 for receiving a user’s head and a visor 7. The cap includes a adjustment strap 8 but may alternatively be elasticated. The apertures 2 are located on the body 6 corresponding to the desired locations of the electrodes 5. In alternative embodiments the headgear may comprise a bandana or wig or hood or turban or any other suitable article of clothing (headwear or headdress) which may be worn upon a user’s head.

The substrate 3 is typically releasably secured within the headgear 1. To this end, the headgear 1 preferably includes one or more retainers for coupling the flexible circuit to the inside of the headgear 1. In preferred embodiments, the retainer(s) comprise one or more receptacle(s) 9 (e.g. a pocket or pouch) provided on the inside of the headgear 1. The or each receptacle 9 is shaped and dimensioned to receive a respective part of the substrate 3, preferably such that the respective part of the substrate 3 is held in a substantially fixed position with respective to the headgear 1 when inserted in the receptacle 9. Advantageously the or each receptacle 9 is located, shaped and dimensioned to receive a respective part of the substrate 3 that carries one or more of the electrodes 5. Typically, at least one of and optionally all of the electrodes 5 are provided on a respective end portion of the substrate 3 (one or more electrode may be provided on the or each end portion), in which case the or each receptacle 9 may be configured to receive a respective end portion of the substrate 3. The receptacles are located such that, when inserted therein, the respective electrode(s) are held at the respective desired location with respect to the user’s head when the headgear 1 is worn. In preferred embodiments, the receptacles 9 are located at pre-determined positions corresponding to the selected electrode positions of the 10-20 system.

The receptacles 9, or other retainers, may be permanently incorporated into the headgear 1, e.g. via stitching, but may alternatively be removably coupled to the headgear 1, e.g. by means of hook and loop fasteners or any other suitable removable coupling means. To facilitate locating the substrate 3 within the headgear 1, the receptacles 9 may include closing means 10 for opening and closing the receptacle, which may for example comprise: hook and loop fasteners; zip; snap fasteners; or any other suitable closing means. In a preferred embodiment the closing means 10 comprises hook and loop fasteners, which have a substantially planar profile such as to reduce bulk within the headgear 1.

The receptacles 9, or other retainers, preferably include a respective aperture 24 for the, or each, respective electrode 5 to be retained in the receptacle 9. The, or each, aperture 24 is positioned such that it is in register with the respective electrode 5 when the electrode 5 is retained within the receptacle 9. The aperture 24 exposes the electrode 5 to the inside of the headgear 1 and therefore to the user’s head when worn. This exposure facilitates contact between the electrode 5 and the head during use. Optionally, the electrode 5, or at least part of it, may project through the respective aperture 24 and/or the aperture 2. Preferably, the apertures 24 in the receptacles 9 are located such as to align with the apertures 2 in the body of the headgear 1, such that the electrodes 5 may be exposed by both apertures 2, 24 simultaneously. Advantageously the apertures 2, 24 facilitate the application of conductive gel to the electrodes during use.

Instead of, or in addition to, the receptacles, one or more retainers in the form of straps (not illustrated) may be provided to secure, preferably releasably, the flexible circuit to the headgear 1 in the same or a similar manner to that described above for the receptacles 9.

In preferred embodiments, the substrate 3 comprises a central portion 11 and a plurality of branches 13 extending laterally therefrom, typically at least one branch 13 extending from each side of the central portion 11. The central portion 11, which is preferably elongate, extends between an anterior portion 12 and a posterior portion 15 of the substrate 3. The or each branch 13 projects from the central portion 11 from a location between the anterior 12 and posterior 15. Typically, at least one electrode 5 (only one on the illustrated embodiment) is provided at the anterior portion 12, preferably at a free end of the substrate. The processing circuitry 4A (preferably all of it) is located at the posterior portion 15. At least one respective electrode 5 is provided on each branch 13, preferably at a free end of the respective branch 13. Each branch 13 may have more than one free end, a respective electrode being provided at each free end. In the illustrated embodiments, each branch 13 has an end portion 13A that runs substantially parallel with the central portion 11 and which carries the respective electrode(s). In preferred embodiments, the central portion 11 and the branches 13 carry the circuit connections between the processing circuitry 4A and the electrodes 5. Optionally, one or more electrodes 5 may be provided on the central portion, for example as shown in Figure 7. Preferably a respective receptacle 9 is provided for each fee end of the substrate 3. A receptacle 9 is preferably provided for the portion of the substrate that carries the processing circuitry 4A, which in some embodiments is located at a free end of the substrate.

When the headgear 1 is worn by a user, the anterior portion 12 is preferably located at the front of the user’s head, typically at or adjacent the user’s nasal bridge or nasion, while the posterior portion 15 is located at the rear of the user’s head, typically at or adjacent the inion. Hence the central portion 11 typically extends in a direction running from the nasal bridge to the spinal column. Advantageously most or all of the circuitry 4, 4A is embedded in the substrate 3 or is substantially flush with its surface, causing the flexible circuit to have a low profile (i.e. be substantially flat) and to have no protruding wires or housings. Accordingly the flexible circuit may be discreetly and comfortably located within the headgear 1.

In a preferred embodiment (as shown in figure 7), a respective branch 13 projects from either side of the central portion 11 from a common location that corresponds to the position Cz of the 10-20 system in-use, i.e. the midway point between the user’s inion and nasion when the headgear is worn. This allows the substrate 3 to be easily aligned upon the user’s head within the headgear 1 with the receptacles 9 being located accordingly such that when the central portion 11 is aligned with the Cz position of a user’s head the branches 13 and more specifically the electrodes 5 are in register with their respective 10-20 positions also. In preferred embodiments, the bulk of the electric circuitry 4 including such components as: power supply, integrated circuits, controller etc. are typically located at the posterior portion 15 which lies against the rear (e.g. at the inion) of the user’s head in-use. To this end the posterior portion 15 of the central portion is preferably insertable into a posterior receptacle 18. The anterior end 12 of the central portion 11 is preferably insertable in an anterior receptacle 19, whilst the first and second branches 16, 17 (or at least the respective end thereof, e.g. end portions 13A) are insertable within corresponding first and second lateral receptacles 20, 21. The power supply typically comprises one or more batteries.

In the preferred embodiment the posterior receptacle 18 located at the posterior of the headgear 1 typically comprises a pocket which is stitched to the headgear 1 along one side whilst removably coupled to the headgear 1 along three remaining sides via hook and loop fasteners such that the posterior portion 15 of substrate 3 may be insertable therein. In an alternative embodiment the posterior receptacle 18 may comprise a pocket which is coupled to posterior of the headgear 1 which incorporates a resealable flap 23 through which the substrate 3, more particularly the posterior portion 15 of the substrate 3 may be inserted.

The flexible circuit may include one or more electrical connectors (not shown) which are configured to allow for removable connection of one or more additional branches 13, each of which includes one or more electrodes 5. The respective connector provides an electrical connection between the electrode(s) of the respective branch 13 and the circuitry 4, in particular the processing circuitry 4A, as well as a mechanical connection to the substrate 3. The headgear 1 may be provided with removable retainers (e.g. a strap or receptacle that can be removable secured to the inside of the headgear by a hook and loop or other releasable fastening device) for securing any additional branches. Figures 10 to 12 show alternative embodiments of the flexible circuit, in which like numerals indicate like parts and in respect of which the same or similar description applies as provided in relation to the previous embodiments. The flexible circuits of Figures 10 and 12 include additional circuit branches 13B located rearwardly of the posterior portion 15 (and of the processing circuitry 4A). These additional circuit branches 13B may be integrally formed with the central portion 11 or removably connected thereto. The circuit branches 13B carry electrodes for monitoring the user’s visual cortex. This is in contrast to the circuit branches 13 located forwardly of the posterior portion 15 which have electrodes 5 for monitoring the user’s motor cortex. It is preferred that the posterior portion 15, including the processing circuitry 4A, is located rearwardly of the circuit branches 13 for monitoring the user’s motor cortex. It is preferred that the posterior portion 15, including the processing circuitry 4A, is located forwardly of the circuit branches 13B for monitoring the user’s visual cortex. In the embodiments of Figures 10 and 12 the posterior portion 15, including the processing circuitry 4A, is located between the circuit branches 13 for monitoring the user’s motor cortex and the circuit branches 13B for monitoring the user’s visual cortex in the front to rear direction. It is preferred that the electrodes 5 are spaced apart from (i.e. forwards, rearwards or to the side of) the processing circuitry 4A to reduce the interference between the two. However, Figure 11 shows an embodiment of the flexible circuit in which the circuitry 4A is located centrally rather than rearwardly on the central portion 11.

Optionally, the flexible circuit may include one or more electrical connector 30 for electrically connecting with another flexible circuit (not shown), the connector 30 typically also providing a mechanical connection between the flexible circuits. The other flexible circuit may be the same or similar to the flexible circuit described above, or may comprise only substrate portion(s) carrying electrode(s) and electrical connection(s), sharing the processing circuitry 4A with the main flexible circuit. The other flexible circuit may include similar connectors for connecting with further flexible circuits. This allows a more complex EEG monitoring device to be constructed in a modular manner, each flexible circuit advantageously providing differently located electrodes to the other(s). In particular, the headgear may comprise adjustable/customisable apertures or connector(s) that allow modularly connected electrode strips to be placed over any area of the scalp, for example, visual cortex, and connected to the recording apparatus contained and concealed in the headgear. A particular advantageous aspect of the headgear 1, is that due to the positioning of the receptacles 9 at pre-determined locations according to the 10-20 system upon the headgear 1, the substrate 3, electrodes 5, when inserted within the receptacles 9 may be held in position over primary motor and sensorimotor areas of the brain for performing an electrophysiological monitoring method upon the user such as an EEG. Sensorimotor rhythms are commonly used in brain-computer interface (BCI) applications and so headgear embodying the invention may be used as a BCI apparatus. Furthermore the flexibility of the substrate 3 allows the electric circuit 4 and corresponding electrodes 5, to flex such as to be located over the primary motor and sensorimotor areas of the brain accommodating variations in head size and shape from user to user.

The invention is not limited to the embodiment(s) described herein but can be amended or modified without departing from the scope of the present invention.

Claims (36)

Claims

1. An electrical measurement apparatus comprising: headgear; a flexible circuit located inside said headgear, the flexible circuit comprising electrical circuitry carried by a flexible substrate, said circuitry comprising a plurality of electrodes connected to processing circuitry, wherein said flexible circuit conforms in use to the shape of a user’s head, said electrodes being spaced apart and located to contact the user’s head in use.

2. The apparatus of claim 1, including one or more retainers for securing said flexible circuit, in particular said electrodes, to the inside of said headgear.

3. The apparatus of claim 2, wherein the or each retainer is configured to releasably secure said flexible circuit to the inside of said headgear, preferably such that said flexible circuit substantially conforms to the shape of the inside of the headgear.

4. The apparatus of claim 2 or 3, wherein a plurality of retainers are provided, each retainer being located for securing a respective portion of said flexible circuit.

5. The apparatus of claim 4, wherein at least one retainer is provided for securing a respective portion of said flexible circuit that carries one or more of said electrodes.

6. The apparatus of claim 4 or 5, wherein at least one retainer is provided for securing a respective portion of said flexible circuit that carries said processing circuitry.

7. The apparatus of any one of claims 2 to 6, wherein at least one of, and optionally all of, said retainers comprises a receptacle, for example a pouch or pocket.

8. The apparatus of claim 7, wherein the or each receptacle comprises at least one receptacle that is permanently incorporated into the inside of the headgear.

9. The apparatus of claim 7 or 8, wherein the or each receptacle comprises at least one receptacle that is releasably connectable to the inside of the headgear.

10. The apparatus of any one of claims 4 to 9, wherein at least one retainer is provided for securing a respective free end portion of said flexible circuit.

11. The apparatus of any preceding claim, wherein said headgear includes a respective aperture for at least one of said electrodes, the respective electrode being in register with the respective aperture when the flexible circuit is inside the headgear, the respective aperture exposing the respective electrode to the outside of the headgear.

12. The apparatus of any preceding claim, wherein the respective retainer includes a respective aperture for the or each respective electrodes, the respective electrode being in register with the respective aperture when the flexible circuit is retained inside the headgear, the respective aperture exposing the respective electrode to the inside of the headgear through the retainer.

13. The apparatus of any preceding claim, wherein said processing circuitry is located in a portion of said flexible circuit that is spaced apart from the respective portions that carry said electrodes.

14. The apparatus of any preceding claim, wherein said flexible circuit comprises an anterior portion and a posterior portion, at least one of said electrodes being located at said anterior portion and/or between said anterior portion and said posterior portion.

15. The apparatus of claim 14, wherein said processing circuitry is located at said posterior portion.

16. The apparatus of claim 14 or 15, wherein said flexible circuit includes a central portion extending between said anterior and posterior portions, at least one electrode being located at said central portion.

17. The apparatus of claim 14, 15 or 16, wherein said flexible circuit includes a central portion extending between said anterior and posterior portions, and further includes at least one branch portion projecting from said central portion, the or each branch portion carrying at least one of said electrodes.

18. The apparatus of claim 17, including first and second of said branch portions projecting from opposite sides of said central portion, preferably from a common location.

19. The apparatus of any preceding claim, wherein at least some of said electrodes are located at a respective end portion of said flexible circuit.

20. The apparatus of any one of claims 14 to 19, wherein flexible circuit is dimensioned and located inside said headgear so that, in use, said anterior portion is substantially in register with the user’s nasion, and said posterior portion is substantially in register with the user’s inion.

21. The apparatus of any one of claims 14 to 20, wherein said flexible circuit includes at least one circuit portion extending rearwardly of said posterior portion, said at least one circuit portion carrying at least one electrode.

22. The apparatus of any preceding claim, wherein said flexible circuit includes at least one electrical connector for releasably connecting with a respective flexible circuit portion that includes at least one electrode.

23. The apparatus of claim 22, wherein the respective electrical connector electrically connects the or each respective electrode of the respective flexible circuit portion to the processing circuitry.

24. The apparatus of claim 22 or 23, wherein the respective electrical connector mechanically connects the respective flexible circuit portion to said flexible circuit.

25. The apparatus of any proceeding claim, wherein said processing circuitry comprises means for recoding electrical signals produced by said electrodes in use and/or measurements derived therefrom.

26. The apparatus of any preceding claim, wherein said flexible circuit is shaped and dimensioned to extend from the nasion to the inion the user.

27. The apparatus as claimed in any preceding claim, wherein said flexible substrate comprises a metal clad substrate, preferably copper clad laminate.

28. The apparatus of any preceding claim, wherein said headgear comprises an article of clothing.

29. The apparatus of claim 28, wherein said headgear comprises a hat.

30. The apparatus of claim 28, wherein said headgear comprises any one of a bandana, a wig, a hood, ora turban.

31. The apparatus of any preceding claim, wherein said electrodes are located within said headgear to align with motor and/or sensorimotor areas of the user’s head in use.

32. The apparatus of any preceding claim, wherein at least some of said electrodes are located within said headgear to align with motor cortex related areas of the user’s head in use.

33. The apparatus of any preceding claim, wherein at least some of said electrodes are located within said headgear to align with visual cortex related areas of the user’s head in use.

34. The apparatus of any preceding claim wherein said electrical circuitry is configured to perform an electrophysiological monitoring method using signals generated by said electrodes in use.

35. The apparatus of claim 34, wherein said electrophysiological monitoring method comprises an electroencephalogram (EEG).

36. An electrical measurement apparatus substantially as hereinbefore described and with reference to the accompanying drawings.