Needle-based electrodes and electrode mounts

Abstract

A needle-based electrode for measuring at least one biosignal from a patient, comprising: an insertable needle portion comprising a needle tip configured for insertion into the patient's skin; and an adaptor portion electrically coupled to the insertable needle portion and configured to electrically couple to one or more electrical cables, wherein the needle-based electrode is electrically conductive to thereby enable measurement of the at least one biosignal

Description

NEEDLE-BASED ELECTRODES AND ELECTRODE MOUNTSField of the Invention

[0001] The invention generally relates to an electrode mount for assisting in the use of needlebased electrodes for measurement of bioelectrical signals, and to needle-based electrodes for use as electrodes, as well as related methods.Background to the Invention

[0002] A number of techniques are available for measuring bioelectrical signals of a patient, such as electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), electrocardiography (ECG), nerve conduction studies (NCS), and the like. As a general operating principle, the bioelectrical signals are measured by placing electrodes to the patient. For example, the electrodes can take the form of contact electrodes which are affixed to the skin of a patient.

[0003] In a human or an animal body, a bioelectrical signal is a signal of / in (e.g., produced by) the body that can be continually measured and monitored. The bioelectrical signal is generally a time-varying signal. The bioelectrical signal may be an electrical bioelectrical signal formed by changes in electric potential, measured over time, produced by a sum of an electrical potential difference across a selected (specialised) tissues system, organ system, or cell system like the nervous system.Summary of the Invention

[0004] According to one or more disclosed embodiments, there is provided a needle-based electrode for measuring at least one biosignal from a patient, comprising: an insertable needle portion comprising a needle tip configured for insertion into the patient’s skin; and an adaptor portion electrically coupled to the insertable needle portion and configured to electrically couple to one or more electrical cables, wherein the needle-based electrode is electrically conductive and thereby configured to measure the at least one biosignal.

[0005] The needle-based electrode optionally comprises a safety portion mechanically and electrically coupled to and axially aligned with the insertable needle portion to conduct an insertion force along the safety portion to the insertable needle portion, wherein the safety portion is configured to buckle when at least a pre-selected axial (e.g., compressive) force is applied axially along the safety portion. The insertable needle portion may be more rigid longitudinally than the safety portion.

[0006] The needle-based electrode optionally comprises an attachment portion mechanically coupled to the insertable needle portion and / or to the safety portion, wherein the attachment portion is configured to be attached to the patient’s skin. The attachment portion may be configured to be attached to the patient’s skin by way of a non-woven fixation tape, an adhesive sheet, or an adhesive bandage holding the attachment portion to the skin, optionally with adhesive glue. The insertable needle portion may be more rigid longitudinally than the attachment portion.

[0007] Optionally, the insertable needle portion includes one or more coatings that reduce friction on insertion of the insertable needle portion into the skin. Optionally, the insertable needle portion includes one or more coatings that reduce the half-cell potential. Optionally, the insertable needle portion includes one or more coatings that reduce or otherwise tailor the impedance between the insertable needle portion and the tissue of the patient once inserted.

[0008] The needle-based electrode is optionally configured to have an electrical impedance less than 10 k , or between 1 kQ to 5 kQ, or less than 1 kQ, which may be the electrical impedance at 10 Hz.

[0009] The insertable needle portion optionally comprises a circular cross-section. Alternatively, the insertable needle portion optionally comprises a non-circular cross-section having a long axis and a short axis. The cross-section may be symmetric about either one or both of the long axis and the short axis. The insertable needle portion may have a diameter or long axis of 300 pm or less, 290 pm or less, 280 pm or less, 270 pm or less, 260 pm or less, 250 pm or less, 240 pm or less, 230 pm or less, 220 pm or less, 210 pm or less, 200 pm or less, 190 pm or less, 180 pm or less, 170 pm or less, 160 pm or less, 150 pm or less, 140 pm or less, 130 pm or less, 120 pm or less, 110 pm or less, or 100 pm or less.

[0010] In use, the insertable needle portion is optionally inserted into the skin at an insertion angle between the insertable needle portion and the skin, wherein the insertion angle is selected to be 45 degrees or less, 40 degrees or less, 35 degrees or less, 30 degrees or less, 25 degrees or less, 20 degrees or less, 18 degrees or less, 17 degrees or less, 16 degrees or less, 15 degrees or less, 14 degrees or less, 13 degrees or less, 12 degrees or less, 11 degrees or less, 10 degrees or less, or 8 degrees or less. The insertion angle may be substantially 20 degrees, 18 degrees, 17 degrees, or 16 degrees.

[0011] The insertable needle portion is optionally at least partially flexible such that the insertable needle portion, when inserted into the epidermis or dermis, can flex in and with the epidermis or dermis. The insertable needle portion may have a Young’s Modulus (E) of less than between 25 and 260 kPa.

[0012] According to one or more disclosed embodiments, there is provided a set of needlebased electrodes, each being the needle-based electrode as above.

[0013] According to one or more disclosed embodiments, there is provided a needle-based method that uses the above set of the needle-based electrode to measure at least one biosignal from a patient.

[0014] The method may include inserting the insertable needle portion into the epidermis or dermis at an insertion angle such that a substantial length of the insertable needle portion lies within the epidermis or dermis once the insertable needle portion has been fully inserted.

[0015] According to one or more disclosed embodiments, there is provided an electrode mount comprising a body having a contact surface for positioning on a patient’s skin, wherein the body comprises one or more electrode guides for facilitating insertion of an electrode member into the patient’s skin at a predefined angle when the contact surface is positioned on the patient’s skin.

[0016] The electrode mount optionally comprises two or more electrode guides. Alternatively, the electrode mount may comprise one electrode guide.

[0017] The one or more electrode guides optionally each define a channel and may have a proximal opening and a distal opening, and each electrode guide may be configured to guide an electrode member inserted into its distal opening towards its proximal opening, such that the electrode member exits the electrode guide at the proximal opening and is guided into the patient’s skin at the predefined angle with respect to the contact surface. The, or each, electrode guide may be substantially elongate. The, or each, electrode guide may comprise a cylindrical-like passage within the body. The electrode guide may comprise a bend such that the predefined angle is substantially different to an angle at which the electrode member enters the electrode guide at the distal opening. The predefined angle may be less than or equal to approximately 5°. The predefined angle may be measured between the contact surface and a direction that the electrode member exits the proximal opening.

[0018] The electrode mount optionally comprises at least one lead connector configured for electrical coupling to a lead, and the at least one lead connector may provide an electrically conductive pathway between an associated at least one inserted electrode member and the lead. The, or each, lead connector may be permanently electrically coupled to a lead. The, or each, lead connector may comprise a lead attachment mechanism enabling a lead to be removably attached and thereby put into electrical contact with its lead connector.

[0019] Each electrode guide is optionally associated with engagement means for securing an inserted electrode member with respect to the electrode guide. At least one engagement meansmay be further adapted to form at least a portion of the electrically conductive pathway between an inserted electrode member and its associated lead. The at least one engagement means may comprise a screw. At least one engagement means and lead connector may comprise the same structure. Said same structure may comprise an electrically conductive tab lockable at a position in contact with an inserted electrode member thereby inhibiting movement of the inserted electrode member and providing the electrically conductive pathway between the inserted electrode member and the lead.

[0020] The contact surface is optionally shaped in accordance with an expected contour of a patient’s skin.

[0021] The electrode mount is optionally configured for use with one or more electrode members corresponding to acupuncture needles or equivalent structures. The electrode mount is optionally configured for use with one or more needle-based electrodes as per the first mentioned aspect. The electrode mount may comprise the attachment portion or a part thereof of the one or more needle-based electrodes. The electrode mount may comprise the adaptor portion or a part thereof of the one or more needle-based electrodes.

[0022] The electrode mount optionally comprises an electrically conductive coupling between two or more inserted electrode members such that the two or more inserted electrode members correspond to a single electrode.

[0023] Optionally, the body comprises two or more spaced apart and aligned feet extending outwards from a common portion of the body.

[0024] According to one or more disclosed embodiments, there is provided an electrode mount system comprising one or more electrode mounts as described above.

[0025] The electrode mount system may further comprise one or more adhesive elements, wherein each adhesive element comprises a patient-side adhesive surface and a mount-side adhesive surface, and wherein the, or each, electrode mount is affixed to the patient’s skin using an adhesive element.

[0026] The electrode mount system may further comprise one or more electrode members, wherein each electrode member comprises a handle, and wherein the electrode guides are configured to block the handles from entering the electrode guides, such as to enable control of a maximum depth of insertion of the electrode members into the patient’s skin.

[0027] According to one or more disclosed embodiments, there is provided a method for using an electrode mount, comprising the steps of: affixing an electrode mount to a location on the patient’s skin, wherein the electrode mount comprising a body having a contact surface forpositioning on a patient’s skin, wherein the body comprises one or more electrode guides for facilitating insertion of an electrode member into the patient’s skin at a predefined angle when the contact surface is positioned on the patient’s skin, and wherein the electrode mount is affixed to the patient’s skin at its contact surface; for the, or each, electrode guide: inserting an electrode member into a distal opening of the electrode guide, and passing the electrode member through the body of the electrode mount via the electrode guide in an insertion direction, such that an end of the electrode member exits the electrode mount at a proximal opening of the electrode guide and enters the patient’s skin; obtain biological signal measurements of the patient using the one or more electrode members; and removing the one or more electrode members from the patient’s skin and the electrode mount by moving the one or more electrode members along the electrode guide in an opposite direction to the insertion direction.

[0028] The method may be applied to the electrode mount as described above.

[0029] As used herein, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.Brief Description of the Drawings

[0030] In order that the invention may be more clearly understood, embodiments will now be described, by way of example, with reference to the accompanying drawing, in which:Figure l is a sketch of a needle-based electrode according to an embodiment;Figure 2 is a sketch of the needle-based electrode of Figure 1 in an inserted condition;Figure 3 is a sketch of the needle-based electrode of Figure 1 in a pre-insertion condition relative to the skin surface;Figure 4 is a sketch of the needle-based electrode of Figure 1 in the inserted condition relative to the skin surface;Figure 5 is a photograph showing the placement of 33 recording electrodes, a reference electrode and a ground electrode on the scalp of a term baby (37 weeks post-menstrual age);Figure 6 is a photograph showing the placement of 33 recording electrodes, a reference electrode and a ground electrode on the scalp of a term baby (37 weeks post-menstrual age);Figure 7 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing normal asynchronous discontinuity — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 8 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing normal background delta brush activity — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 9 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing excess beta background — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 10 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing normal eye flutter or nystagmus — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 11 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing frontal sharp transients (partially left sided) in a subject that was normally bilateral at term and unilateral preterm — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 12 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing a normal awake neonatal trace (low amplitude continuous) — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 13 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing normal neonatal discontinuity (2 to 4 seconds) — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time;Figure 14 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing normal neonatal quiet sleep — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time; andFigure 15 is an excerpt of data recorded using an example of the needle inserted into a newborn patient showing normal 5-6 Hz central rhythms — the Y-axis compares difference in voltage between pairs of electrodes located at different positions on the head, while the X axis shows time.Figures 16A to 16D show different views of an electrode mount according to an embodiment;Figure 17 shows a method for using an electrode mount;Figure 18 shows two electrodes ready for insertion into an electrode mount;Figures 19A and 19B show an embodiment in which a lead is coupled to the electrode mount;Figures 20A and 20B show an embodiment in which a lead is coupled to an electrode;Figure 21 shows an embodiment comprising a lead attachment mechanism comprising conductive tabs located at an end of a lead;Figure 22 shows an electrode mount comprising a lead attachment mechanism according to another embodiment;Figure 23 shows an embodiment utilising a separate adhesive strip;Figures 24A and 24B show four electrode mounts affixed to a patient;Figure 25 shows the use of an applicator tool for assisting in applying electrode mounts to a patient;Figure 26 shows a lead connector including electrical contacts for connection to applicator receiving structures of the electrode mount; andFigures 27A and 27B show preliminary results of using electrode mounts when performing an electroencephalography (EEG) measurement.Description of Embodiments

[0031] Throughout this disclosure, numerical references are used to link specific disclosure to features shown in the drawings. As the drawings may show multiple instances of a feature, a lowercase suffix may be used to distinguish equivalent features. For example, Figures 16A shows two instances of electrode members 11, being electrode member I la and electrode member 11b. Reference may be made to specific instance(s) of features (e.g., reference may be made to one of the following: electrode member I la, electrode member 11b, or electrode members I la, 11b).Reference may also be made to the feature more generally by omitting a lowercase suffix. For example, reference to electrode members 11 is to the feature generally without necessarily referencing a particular instance shown in the relevant feature.

[0032] Embodiments herein described generally relate to and / or utilise one or more needles or needle-based electrodes (or, equivalently, one or more needle-based apparatuses), for example in some embodiments comprising an acupuncture needle. However, reference to a “needle” or “needle-based electrode” is not intended to be limiting in terms of material or structural properties, unless specified otherwise. The needles or needle-based electrodes may be generally elongate and may advantageously balance a requirement for sufficient rigidity to enable insertion into a patient’s skin against a requirement for sufficient flexibility to avoid or at least minimise undue discomfort for the patient once inserted. The flexibility may also advantageously reduce the risk of injury to the clinician. The needles or needle-based electrodes comprise a needle tip (herein also referred to as a “tip”) having sufficient tip sharpness to enable insertion into the patient’s skin. Advantageously, the needles and needle-based electrodes described herein may be inserted into the patient’s skin without the aid of another device inserted into the patient’s skin, such as a trocar. For example, it has been found that an acupuncture needle with a 100 pm or 120 pm diameter may provide a suitable balance between sufficient rigidity to enable insertion into the patient’s skin against a requirement for sufficient flexibility to avoid or at least minimise undue discomfort for the patient once inserted.Needle-based electrode(s)

[0033] Figure 1 shows a schematic representation of a needle-based electrode 80, according to one or more embodiments described herein. The needle-based electrode 80 is configured to measure at least one bioelectrical signal (also referred to as a “biosignal”, an example of which is a biopotential signal) from a patient. The terms “subject” and “patient” are used interchangeably herein and refer to any mammalian subject, including humans and animals. “Measuring” at least one bioelectrical signal can correspond, depending on context, to monitoring and / or detecting the at least one bioelectrical signal.

[0034] The needle-based electrode 80 of Figure 1 comprises an insertable needle portion 81 configured for insertion into the epidermis or dermis of a patient and to measure at least one biosignal from the patient (e.g., as produced within the patient’s body). Depending on the embodiment, the needle-based electrode 80 also comprises an adaptor portion 84 (also referred to as a "connector portion 84") electrically coupled to the needle portion 81 to conduct the measured biosignal, and configured to couple to one or more electrical cables 85 (can also be referred to as “cable(s)”, “electrical lead(s)”, “lead(s)”, or “signal lead(s)”). The one or more electrical cables 85are configured to carry the measured biosignal to an electronic amplifier / receiver system configured to record, perform analysis and / or display of the measured / detected biosignal.

[0035] The needle-based electrode 80 may itself be referred to as a "needle" or a portion of a needle, or an "electrode" as described hereinafter.

[0036] The needle-based electrode 80 may be referred to as an "electrode" because it connects the biosignals from a patient to medical machines and / or other equipment that measure the biosignals, including by making measurements through the patient’s skin, e.g., to perform electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), electrocardiography (ECG), or nerve conduction studies (NCS).

[0037] Still with reference to Figure 1, in at least one embodiment, the needle-based electrode80 comprises a portion (“safety portion”) 82 mechanically coupled to and axially aligned with the insertable needle portion 81 to conduct an insertion force along the safety portion 82 to the insertable needle portion 81. The safety portion 82 is typically electrically coupled to the insertable needle portion 81 to conduct the measured biosignal, for example from the insertable need portion81 to the adaptor portion 84. The safety portion 84 is configured to buckle or otherwise deform when at least a pre-selected axial (e.g., compressive) force FCr is applied axially along the safety portion 84.

[0038] Also, in at least one embodiment, the needle-based electrode 80 comprises an attachment portion 83 mechanically coupled to the needle portion 81 optionally via the safety portion 82 (thus the attachment portion 83 can be located between the needle portion 81 and the safety portion 82, or between the safety portion 82 and the adaptor portion 84). The attachment portion 83 is configured to be fastened or otherwise attached to the patient’s skin, e.g., by way of a non-woven fixation tape, an adhesive sheet, or an adhesive bandage holding the attachment portion 83 on to the patient’s skin (optionally with adhesive glue).

[0039] It should be understood that reference to a feature being fastened to, attached to, or otherwise located on to the patient’s skin is a reference to an external surface of the patient’s skin. On the other hand, reference to a feature being inserted into or otherwise being located within the patient’s skin is a reference to the feature being present underneath the external surface of the patient’s skin (e.g., depending on the context, said feature may be within the epidermis, dermis, and / or another layer of the patient’s skin).

[0040] Where applicable, the combination of the insertable needle portion 81, the optional safety portion 82, the optional attachment portion 83, and the adaptor portion 84 can collectively be referred to as a “needle”.

[0041] The insertable needle portion 81, the optional safety portion 82, the optional attachment portion 83, and the adaptor portion 84 can be substantially formed of materials (e.g., stainless steel) that can be sterilised (e.g., sterilised with ethylene oxide) before use.

[0042] According to at least one embodiment, the insertable needle portion 81 is adjacent to and electrically coupled to the adaptor portion 84, and therefore the needle-based electrode 80 does not require the safety portion 82 or the attachment portion 83. Alternatively, in at least one alternative embodiment, the needle-based electrode 80 comprises the insertable needle portion 81, the attachment portion 83, and the adaptor portion 84, and the attachment portion 83 can be located between the needle portion 81 and the adaptor portion 84 — thus the attachment portion 83 can be positioned (e.g., arranged, located, and / or used) close to or at the point of penetration into the patient’s skin. In at least one other alternative embodiment, where the needle-based electrode 80 comprises the insertable needle portion 81, the safety portion 82, and the adaptor portion 84, the safety portion 82 can be located between the needle portion 81 and the adaptor portion 84 so that the safety portion 82 can be gripped by a clinician or other user as the needle portion 81 is inserted into the patient’s skin.

[0043] As shown in Figure 1 and Figure 2, the attachment portion 83 can be mechanically attached to the needle portion 81, and the safety portion 82 can be located between the needle portion 81 and the adaptor portion 84. Alternatively, where the apparatus 80 comprises the needle portion 81, the safety portion 82, the attachment portion 83, and the adaptor portion 84, the attachment portion 83 can be located between the needle portion 81 and the safety portion 82, with the adaptor portion 84 adjacent to the safety portion 82 — thus the attachment portion 83 can be located close to the point of penetration into the patient’s skin while the safety portion 82 can be gripped by the clinician. In another alternative, where the apparatus 80 comprises the needle portion 81, the safety portion 82, the attachment portion 83, and the adaptor portion 84, the attachment portion 83 can be located between the safety portion 82 and the adaptor portion 84, with the safety portion 82 adjacent to the needle portion 81 — thus the attachment portion 83 can be located away from the point of penetration into the patient’s skin since the safety portion 82 will typically be located between the attachment portion 83 and the point of penetration into the patient’s skin.

[0044] According to one or more embodiments, the insertable needle portion 81 is configured for insertion into the epidermis 93 of the skin of a patient. According to one or more embodiments, the insertable needly portion 81 is configured for insertion through the epidermis 93 and into the underlying dermis 94 of the skin of a patient. The insertable needle portion 81 is generally configured to measure at least one biosignal of the patient.

[0045] The epidermis 93 is the outermost layer of skin in mammals. It is relatively thin, is composed of keratin-filled cells. The epidermis 93 serves as a barrier to water and to invasion by pathogens. The epidermis 93 is made up of five individual layers. The “stratum corneum” is the top layer of the epidermis 93 that helps the skin retain moisture and prevents unwanted substances from entering the body and is made of dead, flattened keratinocytes that are shed approximately every two weeks. The “stratum lucidum” is a translucent layer of tissue that exists only on the palms of the hands and the soles of the feet. The “stratum granulosum” is a layer that contains more keratinocytes that are gradually pushed toward the surface of the skin. The “stratum spinosum” is also known as the squamous cell layer and is the thickest part of the epidermis 93 that contains newly formed keratinocytes (that produce a protein called keratin that makes up hair, skin, and nails) as well as Langerhans cells that help fight infection. The “stratum basale” is the bottom layer of the epidermis 93 (also known as the basal cell layer) and has column-shaped cells that push older cells toward the surface. As the cells move upward, they start to flatten and die. The layer is also made up of melanocytes (that produce a pigment that gives the skin its colour) and Merkel cells that act as receptors to touch. The thickness of the epidermis 93 depends on where it is located on the body, and is thinnest on the eyelids (about 0.05 millimetres) and thickest on the palms of the hands and the soles of the feet (1.5 millimetres). The thickness of the epidermis 93 on the scalp varies with age between a minimum of 0.35 mm in childhood and maximum of 0.7 mm in early adulthood. The five layers of the epidermis 93 can also be referred to as the superficial layers of the skin or the superficial dermis. Therefore, reference to the surface of the patient’s skin may be understood as a reference to the external facing surface of the epidermis 93.

[0046] The dermis 94 is a layer of skin between the subdermis 95 and the epidermis 93 (which includes epidermal cells). The dermis 94 includes primarily dermal cells that provide dense irregular connective tissue. The dermis 94 includes two layers. The “papillary region” is adjacent to the epidermis 93 and is a thin layer that contains capillaries (that help regulate skin temperature and provide nutrients to the epidermis), Meissner corpuscles (that transmit sensations of delicate touch) and lamellar corpuscles (that transmit sensations of vibration and pressure). The “reticular dermis” is a thick, lower layer that contains connective tissues and dense collagen bundles that provide the skin with its overall elasticity and strength. The dermis 94 is tightly connected to the epidermis 93 through a basement membrane. Structural components of the dermis include: collagen, elastic fibres, and an extrafibrillar matrix. The dermis 94 contains mechanoreceptors that provide the sense of touch, and thermoreceptors that provide the sense of heat, which are of greatest density in the reticular dermis. Hair follicles, sweat glands, sebaceous glands (oil glands), apocrine glands, lymphatic vessels, nerve endings and blood vessels are present in the dermis. These blood vessels provide nourishment and waste removal for the dermal cells and the epidermalcells. The thickness of the dermis depends on where it is located on the body, and is thinnest on the eyelids (about 0.5 mm) and thickest on the palms of the hands and the back (up to about 10 mm in some cases). The thickness of the dermis on the scalp varies with age between a minimum of 0.7 mm in childhood and maximum of 1.7 mm in early adulthood. On average, the dermis 94 can be between 0.5 and 5 millimetres thick, for example in certain areas.

[0047] The insertable needle portion 81 can be configured for insertion into the epidermis 93 or for insertion into the dermis 94 (via the epidermis 83). Where the insertable needle portion 81 is configured for insertion into the epidermis 93, the insertable needle portion 81 is configured to be inserted into the epidermis 93 without penetrating the dermis 94. Where the needle portion 81 is configured for insertion into the dermis 94 the needle portion 81 is configured to pass through the epidermis 93 and be inserted into the dermis 94. In some embodiments, the needle portion 81 is configured for insertion through the epidermis 93 and into the papillary region of the dermis 94, without penetrating into the reticular dermis. In at least one embodiment, in use, the needle portion 81 is not intended to penetrate completely through the dermis 94 or into the sub-dermis 95.

[0048] The insertable needle portion 81 can be configured for insertion so that the tip 86 of the insertable needle portion 81 is located at a depth (perpendicular to the surface of the skin) of 12 mm or less, 11 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, 1 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, or 0.1 mm or less from the surface of the patient’s skin.

[0049] The insertable needle portion 81 can be at least 1 mm, at least 2 mm, at least 3 mm, at least 4 mm, at least 5 mm, at least 6 mm, at least 7 mm, at least 8 mm, at least 9 mm, at least 10 mm, at least 15 mm, at least 20 mm, at least 25 mm, at least 30 mm or more in length. The insertable needle portion 81 may be less than 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, or 30 mm in length. In an example needle-based electrode 80 (e.g., configured for infant scalp insertion), the insertable needle portion 81 can be at least 1 mm and less than 20 mm in length. In an example, the insertable needle portion 81 can be substantially 30 mm long, and the length generally inserted in the method of use thereof may be substantially 10-15 mm.

[0050] The insertable needle portion 81 may be configured so that at least 0.02 mm2, at least 0.03 mm2, at least 0.04 mm2, at least 0.05 mm2, at least 0.06 mm2, at least 0.07 mm2, at least 0.08 mm2, at least 0.09 mm2, at least 0.1 mm2, at least 0.11mm2, at least 0.12 mm2, at least 0.13 mm2, at least 0.14 mm2, at least 0.15 mm2, at least 0.16 mm2, at least 0.17 mm2, at least 0.18 mm2, at least 0.19 mm2, at least 0.2 mm2, at least 0.21 mm2, at least 0.22 mm2, at least 0.23 mm2, at least 0.24 mm2, or at least 0.25 mm2of its outer surface can be inserted into the dermis 94 and / orepidermis 93. In examples, having the outer surface area of the insertable needle portion 81 (which depends on its average diameter and length) larger may advantageously provide a larger and better biosignal, whereas having the outer surface area smaller may advantageously reduce friction between the insertable needle portion 81 and the dermis 94 and / or epidermis 93, thus may reduce pain and / or discomfort, so different outer surface areas may be selected based on the application. For example, the biosignals required, the age and / or size of the patient, and / or the location of the insertion point on the patient’s skin, and / or the thickness of the patient’s skin at the insertion point.

[0051] In the human or animal body, a biosignal is a signal generated or otherwise associated with the body that can be continually measured and monitored. The biosignal may refer to electrical and non-electrical signals. The biosignal is generally a time-varying signal. The biosignal may be an electrical biosignal formed by changes in electric potential, measured over time, produced by a sum of an electrical potential difference across a selected (specialised) tissues system, organ system, or cell system like the nervous system.

[0052] The insertable needle portion 81 may be described as an "electrically conductive probe" or “electrode” when it is configured to measure electrical biosignals, including in the form of biopotentials, which may be relevant for clinical electrophysiology. The needle-based electrode80 can be suitable for use in a range of applications in which biopotentials can be measured using the apparatus having the insertable needle portion 81 inserted into the epidermis 93 or dermis 94. With the electrically conductive probe, the method may include electroencephalography (EEG), electromyography (EMG), electrooculography (EOG), electrocardiography (ECG), or nerve conduction studies (NCS).

[0053] The insertable needle portion 81 and / or the whole apparatus 80 may be referred to as a "probe" because it is configured to measure biosignals of the patient and thus configured for measuring the biosignal(s).

[0054] In one or more embodiments, the insertable needle portion 81 includes one or more coatings that reduce friction on insertion of the insertable needle portion 81 into the patient’s skin and / or that reduce or otherwise tailor the half-cell potential or the impedance between the insertable needle portion 81 and the tissue of the patient. In at least one embodiment, the insertable needle portion 81 includes a low-friction coating with a low-friction material. The low-friction material can include a low friction polymer, e.g., polytetrafluoroethylene (PTFE) or Teflon(TM). The low-friction coating coats (or otherwise covers) some or all of the insertable needle portion81 at its distal or proximal end, i.e., the end closest to or away from its free tip 86, and can cover 0% or less than 10%, 20%, 40%, 60%, 80% or 90% or 100% of the insertable needle portion 81 to reduce the friction of insertion. The low-friction coating can coat or otherwise cover a portionor all around the longitudinal sides of the insertable needle portion 81 : the low-friction coating may extend along one longitudinal side of the insertable needle portion 81 and an impedance matching coating, comprising electrically conductive materials, may extend along another longitudinal side of the insertable needle portion 81. If the low-friction material is not electrically conductive, at least a portion of the insertable needle portion 81 can be free of the low-friction coating. The insertable needle portion 81 can include the impedance matching coating comprising electrically conductive materials. The electrically conductive material may include silver, e.g., silver and silver chloride (e.g., in the form of an Ag / AgCl coating). The silver coating may be described as a bilayer of Ag and AgCl, which are arranged together such that the silver chloride coats the outer surface and the silver chloride interacts with dissolved chloride in solution to benefit the biosignal measurements. In an example, the outer surface of the insertable needle portion 81 may be coated with a layer suitable to receive a silver layer, such as a copper layer, which is then coated with a silver (Ag) layer, and the silver layer is coated with silver chloride (AgCl). The electrically conductive material may coat or otherwise cover some or all of the insertable needle portion 81 at its proximal or distal end, i.e., the end closest to or away from its free tip 86, and can cover up to 100%, 80%, 60%, 40% or 20% of the insertable needle portion 81, e.g., just a small area (e.g., 10% or less) of the insertable needle portion 81. If the insertable needle portion 81 includes the electrically conductive material coating and a low-friction material coating that is not electrically conductive, the insertable needle portion 81 can include the electrically conductive material coating on at least a portion of the insertable needle portion 81 that is free of the low- friction coating.

[0055] When in use, the needle-based electrode 80 can be configured to have an impedance less than 10 kQ, for example, between 1 kQ to 5 kQ. In at least one embodiment, the needle-based electrode 100 has an impedance that is less than 1 k . As electrical impedance is typically frequency-dependent, the impedance can be at 10 Hz.

[0056] The insertable needle portion 81 may be referred to as an "intraepidermal needle portion" or an "intradermal needle portion". The intraepidermal or intradermal needle portion is configured to be inserted into the epidermis 93 or dermis 94 but not necessarily through the dermis 94, such that the tip 86 of the insertable needle portion 81 lies in the epidermis 93 or dermis 84, thus “intraepidermally” or “intradermally”. For insertion into the epidermis 93 or dermis 84, the insertable needle portion 81 has at least one dimension perpendicular to the longitudinal axis (along the length of the insertable needle portion 81) that is sufficiently thin to permit the intraepidermal or intradermal insertion without penetrating through / beyond the dermis. The needle portion may have at least one such perpendicular dimension that is 300 pm or less, 290 pm or less,280 pm or less, 270 pm or less, 260 pm or less, 250 pm or less, 240 pm or less, 230 pm or less,220 pm or less, 210 pm or less, 200 pm or less, 190 pm or less, 180 pm or less, 170 pm or less,160 pm or less, 150 pm or less, 140 pm or less, 130 pm or less, 120 pm or less, 85 pm or less or80 pm or less. In some implementations, the at least one perpendicular dimension is substantially perpendicular to the surface of the patient’s skin when the insertable needle portion 81 is being inserted; in other implementations, the at least one perpendicular dimension is substantially 45 degrees to the surface of the patient’s skin when the insertable needle portion 81 is being inserted (when the insertable needle portion 81 is inserted in a direction substantially 45 degrees to the surface of the patient’s skin).

[0057] In one or more embodiments, the insertable needle portion 81 has a substantially circular cross-section. The cross-section can be relatively uniform along the length of the needle portion. The perpendicular dimension can be substantially the diameter of the insertable needle portion 81.

[0058] In at least one alternative embodiment, the insertable needle portion 81 has a noncircular cross-section. For example, the non-circular cross-section can be characterised by having a long axis and a short axis (i.e., the long axis has a larger length than the short axis). The long axis and short axis are typically perpendicular to one another. The cross-section can be symmetric about either or both of the short axis and the long axis. In an embodiment, the insertable needle portion 81 has a substantially oval cross-section along the length of the insertable needle portion 81. In another embodiment, the insertable needle portion 81 has a substantially rectangular crosssection along the length of the insertable needle portion 81. In each case, the long axis can be oriented substantially parallel to the surface of the patient’s skin when the need is being inserted. For example, a substantially flat (e.g., wherein the long axis is substantially longer than the short axis) insertable needle portion 81 can be oriented with its flat side partially or substantially parallel to the surface of the patient’s skin when the insertable needle portion 81 is being inserted: thus, even a wide insertable needle portion 81 can be inserted into the epidermis 93 and / or dermis 94 without penetrating beyond the dermis 94.

[0059] In each case, it can be preferred that the short axis (i.e., the dimension of the crosssection that is smaller) is oriented substantially perpendicular to the surface of the patient’s skin when the needle is being inserted.

[0060] Referring to Figure 3, the insertable needle portion 81 is configured for insertion into the patient’s skin at a selected insertion angle 87 (between the insertable needle portion 81 and the surface of the patient’s skin). The selected insertion angle 87 can be a maximum insertion angle 87, such that the insertable needle portion 81 can be effective when inserted at a shallower angle. It should be understood that there is typically some tolerance in relation to the insertion angle 87.The method includes inserting the insertable needle portion 81 at the insertion angle 87. In some embodiments, the insertion angle 87 is selected to be 45 degrees or less, 40 degrees or less, 35 degrees or less, 30 degrees or less, 25 degrees or less, 20 degrees or less, 18 degrees or less, 17 degrees or less, 16 degrees or less, 15 degrees or less, 14 degrees or less, 13 degrees or less, 12 degrees or less, 11 degrees or less, 10 degrees or less, or 8 degrees or less.

[0061] According to at least one embodiment, the insertion angle 87 (between the needle portion and the surface of the patient’s skin) is selected to be less than 45 degrees such that a substantial length of the insertable needle portion 81 lies within the epidermis 93 or dermis 94 once the insertable needle portion 81 has been fully inserted. The insertion angle 87 can thus be referred to as an “intraepidermal insertion angle” or an “intradermal insertion angle”. Accordingly, the insertion angle 87 can be substantially less than 45, 40, 35, 30, 25, 20, 18, or 17 degrees, e.g., substantially 20 degrees, 18 degrees, 17 degrees, or 16 degrees.

[0062] In at least one embodiment, the insertable needle portion 81 is relatively rigid (for example, more rigid longitudinally than the safety portion 82 and / or the attachment portion 83), allowing the needle-based electrode 80 to be held by the clinician at the insertion angle 87 relative to the surface of the patient’s skin during insertion. The other portions of the needle-based electrode 80 (e.g., including, where applicable, the safety portion 82 and / or the attachment portion 83) are relatively flexible, compared to the insertable needle portion 81, such that said other portions can lie (or otherwise fall) against the surface of the patient’s skin once the insertable needle portion 81 inserted, regardless of the insertion angle 87. Having these other portions of the needle-based electrode 80 being relatively flexible means they can be arranged to not project away from the insertion point (i.e., where the insertable needle portion 81 pierces the patient’s skin), which may advantageously avoid or reduce the likelihood of said other portions potentially pulling and / or pushing on the insertable needle portion 81 once it has been inserted (e.g., due to inertia / weight of said other portions, such as during movement of the patient).

[0063] Referring to Figure 4, the inserted angle 88 (between the needle portion 81 and the surface of the patient’s skin after insertion, as shown) may be selected to be less than 45 degrees such that the insertable needle portion 81 is at least partially parallel to the surface of the patient’s skin when it is in place in its operational / probe location in the epidermis / dermis. Having a shallow inserted angle 88 (e.g., of less than 45 degrees), may advantageously improve measurement of surface biopotentials as the inserted insertable needle portion 81 lies substantially parallel to the surface of the patient’s skin. The shallow inserted angle 88 may advantageously better align the insertable needle portion 81, that forms an electrode, with electric fields in the body (“bioelectric fields”), e.g., generated by neural activity (e.g., a shallow inserted angle of less than 45 degreescould enable a projection of more than 70% of parallel components of the bioelectric fields, thus may advantageously improve the sensitivity of the needle-based electrode 80 to the bioelectric fields). In some embodiments, the inserted angle 88 is selected to be 45 degrees or less, 40 degrees or less, 35 degrees or less, 30 degrees or less, 25 degrees or less, 20 degrees or less, 18 degrees or less, 17 degrees or less, 16 degrees or less, 15 degrees or less, 14 degrees or less, 13 degrees or less, 12 degrees or less, 11 degrees or less, 10 degrees or less, or 8 degrees or less.

[0064] Using intraepidermal or intradermal insertion of the insertable needle portion 81, including at the intraepidermal or intradermal insertion angle 87, may advantageously avoid or at least reduce the problem of the insertable needle portion 81 hurting patients on insertion by maintaining the tip 86 in the epidermis 93 and / or the upper layers of the dermis 94, e.g., which may correspond to a depth of less than 12 mm, measured perpendicularly from the surface of the patient’s skin (depending on the patient and which surface of the body is being monitored). Generally, these layers of the patient’s skin have fewer pain receptors than the lower layers of the dermis 94. In some embodiments, the tip 86 is maintained 12 mm or less, 11 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, 1 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, or 0.1 mm or less from the surface of the patient’s skin (measured perpendicularly from the surface of the patient’s skin) when the needle portion 81 is inserted (depending on the thickness of the epidermis 93 and upper layers of the dermis 94 at the insertion point).

[0065] In one or more embodiments, the intraepidermal or intradermal insertable needle portion 81 comprises at least one dimension perpendicular to its longitudinal axis (e.g., for a non-circular cross-section, the perpendicular dimension can correspond to its long axis) along the length of the insertable needle portion 81 of 300 pm or less. In the case of a circular cross-section, for example, having a diameter or at least average diameter over the length of the insertable needle portion 81 of 300 pm or less. Having at least one dimension perpendicular to the longitudinal axis of the insertable needle portion 81 of 300 pm or less may provide at least one of the following advantages: reduced difficulty of inserting the needle tip 86 into the dermis 94, particularly where the patient’s skin is thin (e.g., on the animal or human’s scalp (which is required for EEG)); and reduced force needed to penetrate the patient’s skin and / or force needed to advance the insertable needle portion 81 into the epidermis 93 or dermis 94 (compared to thicker needles). For example, the insertable needle portion 81 having at least one dimension perpendicular to the longitudinal axis (along the length of the insertable portion) of 300 pm or less (e.g., having an average diameter of 300 pm or less) may act to reduce a surface area of contact between the insertable needle portion 81 and the patient’s skin into which it is inserted, thus advantageously reducing friction betweenthe insertable needle portion 81 penetrating into and passing through the epidermal and / or dermal tissue. Also, for example, the insertable needle portion 81 having at least one dimension perpendicular to the longitudinal axis (along the length of the insertable portion) of 300 pm or less (e.g., having an average diameter of 300 pm or less) may act to reduce a radius of strain applied by the insertable needle portion 81 to the surrounding tissue and nerve endings. The insertable needle portion 81 can have at least one dimension perpendicular to the longitudinal axis (along the length of the insertable portion) — e.g., an average diameter — of 290 pm or less, 280 pm or less, 270 pm or less, 260 pm or less, 250 pm or less, 240 pm or less, 230 pm or less, 220 pm or less, 210 pm or less, 200 pm or less, 190 pm or less, 180 pm or less, 170 pm or less, 160 pm or less, 150 pm or less, 140 pm or less, 130 pm or less, 120 pm or less, 85 pm or less, or 80 pm or less.

[0066] In some embodiments, the insertion angle 87 is 45 degrees or less, 40 degrees or less, 35 degrees or less, 30 degrees or less, 25 degrees or less, 20 degrees or less, 18 degrees or less, 17 degrees or less, 16 degrees or less, 15 degrees or less, 14 degrees or less, 13 degrees or less, 12 degrees or less, 11 degrees or less, 10 degrees or less, or 8 degrees or less.

[0067] In one or more embodiments, the distal end of the insertable needle portion 81 includes the tip 86 (which may be referred to as the "needle tip") with a shape such that the tip 86 is sharp to assist in insertion of the insertable needle portion 81 through the surface of the patient’s skin and / or to puncture the patient’s skin by reducing the force required axially along the insertable needle portion 81 to puncture the surface of the patient’s skin. The sharpness of the tip 86 may advantageously reduce the likelihood that a nearby mechanoreceptor pain fibre is activated by the insertion. The shape of the sharp needle tip may include a taper point tip, a triangular tip, a taper cutting tip, a reverse cutting tip, a spatula tip, and a coronary tip. In embodiments, any tip suitable to puncture the patient’s skin may be used.

[0068] In one or more embodiments, the insertable needle portion 81 is at least partially flexible (including when configured for intraepidermal or intradermal insertion) such that the insertable needle portion 81, when inserted, can flex in and with the epidermis 93 or dermis 94 (e.g., in the scalp) to advantageously reduce mechanical pressure exerted from the inserted needle portion 81 into the tissue that surrounds it. An at least partially flexible insertable needle portion 81 may advantageously address problems of insertable needle portions 81 being uncomfortable after insertion or causing pressure injuries (due to compression or tension of the patient’s skin), e.g., due to static sheer force (F) between the tissue and the insertable needle portion 81 that would otherwise activate mechanoreceptors or damage the patient’s skin due to compression of the tissue beneath or tenting of the patient’s skin above due to an otherwise rigid needle. For example, an at least partially flexible insertable needle portion 81 can conform to a curved tissue path.

[0069] An at least partially flexible insertable needle portion 81 may advantageously reduce discomfort from the insertable needle portion 81 after insertion because the force required to bend the insertable needle portion 81 is less than the force required for tissue compression, which may thereby avoid or at least reduce an ongoing compressive force exerted by the insertable needle portion 81 (due to the insertable needle portion 81 tending to straighten), thereby avoiding or at least reducing stimulation of the mechanoreceptor pain fibres. According to at least one embodiment, the insertable needly portion 81 comprises a Young’s Modulus (E) of less than the Young’ s Modulus of the skin (Eskin). For example, depending on the location on the body for which the insertable needle portion 81 is intended to be used, it can be configured to have a maximum Young’s Modulus (E) between 25 and 260 kPa.

[0070] An example embodiment of the insertable portion 81 includes an Ag / AgCl coated stainless steel insertable needle portion 81 of 10 mm length with a circular cross-section, for example having diameter of 120 pm, and a taper point with tip angle 20 degrees and taper ratio 12: 1.

[0071] In one or more embodiments, the attachment portion 83 comprises a flat portion. The flat portion is configured to be fastened to the surface of the patient’s skin to thereby fasten the needle-based electrode 80 in place after insertion of the insertable needle portion 81 into the epidermis 93 or dermis 94. The flat portion configured to lie, rest, or otherwise contact the surface of the patient’s skin The flat portion can have a surface area (configured to be attached substantially parallel to the surface of the patient’s skin) of, for example, about 10 mm2to about 50 mm2, and a thickness (perpendicular to the surface of the patient’s skin) of for example about 0.3 mm to about 1 mm.

[0072] In one or more embodiments, the attachment portion 83 comprises a soft portion. In at least one embodiment, the soft portion corresponds to the flat portion. The soft portion is configured to conform to local irregularities in the contours of the surface of the patient’s skin between the flat portion and the surface of the patient’s skin. The soft portion can have a natural flexibility, compliance, or resilience to enable it to conform to the local irregularities. Advantageously, this may mitigate pressure points on the surface of the patient’s skin when the soft portion is fastened to the surface of the patient’ s skin. The soft portion and / or flat portion may include, for example, a hydrocolloid gel, a foam and / or a non-woven fabric.

[0073] An example embodiment of the attachment portion 83 includes a soft flat shape to protect against pressure injury and optionally a porous surface to facilitate adhesion to the surface of the patient’s skin.

[0074] According to one or more embodiments, the needle-based electrode 80 comprises a safety portion 82 (which may also be referred to as a "flexible portion 82" or a "grippable portion 82") configured to buckle when a pre-selected axial (e.g., compressive) force (which is referred to as “Euler’s critical buckling force”) FCr is applied longitudinally along the safety portion 82. A needle-based electrode 80 comprising a safety portion can be described as a “safety needle”. The safety portion 82 may advantageously avoid, or at least reduce, the problem of accidental needle stick injuries. The critical buckling force (Fcr) is pre-selected to be less than the force required for skin penetration (Fpen) for the animal or human. The selected critical buckling force (Fcr) is less than Fpen. For example, the force required for skin penetration (Fpen) may be substantially equal to, or greater than, twice the critical buckling force (Fcr) (e.g., Fpen> 2Fcr).

[0075] In use, the critical buckling force (Fcr) of the safety portion 82 is effectively manually increased by a person holding the safety portion 82 (which may be referred to as “bracing” the safety portion 82, and the held safety portion 82 may be referred to as a “braced safety portion 82”), for example on opposed longitudinal sides of the safety portion 82 (e.g., with fingers or finger and thumb). The braced safety portion 82 has an effective critical buckling force (Fcr) that is higher than the force required for skin penetration (Fpen), so the needle portion can be inserted into the patient’s skin without buckling of the safety portion 82. This may be due to the braced safety portion 82 having a reduced effective length, which thereby changes its effective critical buckling force (Fcr) such that Fcr> Fpenand insertion of the insertable needle portion 81 can occur. If the safety portion 82 of the “safety needle” needle based apparatus 80 is not braced in this way, accidental needle stick injury may advantageously be avoided because the needle based apparatus 80 will buckle (i.e., at the safety portion 82) instead of penetrating the patient’s skin.

[0076] In at least one embodiment, the insertable needle portion 81 corresponds to a relatively rigid or inflexible portion of the needle-based electrode 80 (which may also be referred to as a “tip portion”) when compared to the safety portion 82. That is, the portion of the needle-based electrode 80 between the safety portion 82 and the tip 86 is relatively more rigid than the safety portion 82. The insertable needle portion 81 can have a critical buckling force (Fcr) substantially larger (e.g., 10 times larger) than the critical buckling force (Fcr) of the safety portion 82.

[0077] In general, a higher rigidity of the insertable needle portion 81 may allow for easier insertion of the insertable needle portion 81 into the patient’s skin. However, a lower rigidity of the insertable needle portion 81 may be preferred once inserted, as a lower rigidity may lead to improved patient comfort. In embodiments in which bracing is utilised, the overall rigidity of the needle-based electrode 80 may advantageously be reduced when compared to not relying uponbracing, as the act of bracing has the effect of increasing the rigidity of the needle-based electrode 80 during the act of inserting of the insertable needle portion 81.

[0078] The safety portion 82 can include an insulator around an electrically conductive core to mitigate interference to or detection of unwanted artefacts in the measured biosignal. The insulator may include an insulating coating or sheet, e.g., including an insulating polymer, e.g., polytetrafluoroethylene (PTFE) or Teflon(TM).

[0079] The safety portion 82 can also, or alternatively, include electromagnetic shielding (e.g., a coating / sleeve) to mitigate the safety portion 82 picking up undesirable electromagnetic signals, e.g., from electrical equipment or cables close to the patient. The electromagnetic shielding can include an electrically conductive coating or sheet around the insulator of the safety portion 82 or, if the insulator is not present, around the conductive core of the safety portion 82.

[0080] In one or more embodiments, the adaptor portion 84 forms an electrical connection between the insertable needle portion 81 (optionally via the safety portion 82) and a non-tip end (proximal end) of the needle-based electrode 80, which is the end configured for connection to a medical monitoring machine or other equipment. For example, the adaptor portion 84 is configured to connect the insertable needle portion 81 to electronic amplifier systems of the medical monitoring machine or other equipment.

[0081] The adaptor portion 84 is electrically coupled to the insertable needle portion (optionally via the safety portion 82 and / or the attachment portion 83) to conduct the measured biosignal. The adaptor portion 84 is configured to couple to one or more electrical cables 85 that are configured to carry the measured biosignal to an electronic receiver system (which can correspond to, or include, an amplifier system) of the medical machine. The medical machine is typically configured to record, perform analysis, and / or display the measured biosignal.

[0082] The adaptor portion 84 can include an insulator around its electrically conductive core to mitigate interference to or detection of unwanted artefacts in the measured biosignal. The insulator may include an insulating coating or sheet, e.g., including an insulating polymer, e.g., polytetrafluoroethylene (PTFE) or Teflon(TM).

[0083] The adaptor portion 84 can also, or alternatively, include electromagnetic shielding (e.g., a coating / sleeve) to mitigate the safety portion 82 picking up undesirable electromagnetic signals, e.g., from electrical equipment or cables close to the patient. The electromagnetic shielding can include an electrically conductive coating or sheet around the insulator of the adaptor portion 84 or, if the insulator is not present, around the conductive core of the adaptor portion 84.

[0084] In at least one embodiment, the safety portion 82 and the adaptor portion 84 share the same insulator and / or electromagnetic shielding.

[0085] In one or more embodiments, the needle-based electrode 80 is provided in a kit or assembly comprising at least two or more needle-based electrodes 80, thus forming a set of the needle-based electrodes 80. Each needle-based electrodes 80 in the kit or assembly typically has the same mechanical and electrical configuration, but each needle-based electrode 80 in the set may be visually or otherwise distinguished (for example, through the use of distinguishing labelling and / or colouring) so that a clinician using the kit or assembly can easily conveniently identify which pairs of ends (tip end 86 and non-tip end (e.g., adaptor portion 84 end)) correspond to each other in the kit or assembly. In the assembly, the set of needle-based electrodes 80 may be separably joined, e.g., in a pack. In the kit, the set of needle-based electrodes 80 may be provided together, e.g., in a sterile container. For EEG, the kit or assembly can include at least three needle-based electrodes 80 (e.g., referred to as "electrodes"), comprising a reference electrode, a ground electrode and a signal electrode, thus allowing at least one EEG biopotential signal to be recorded. For ECG, EMG or EOG, the kit or assembly can include at least two needlebased electrodes 80 (e.g., referred to as "electrodes"), comprising a bipolar pair of electrodes, thus allowing at least one ECG, EMG or EOG biopotential signal to be recorded. For NCS, the kit or assembly may include at least three needle-based electrodes 80 (e.g., referred to as "electrodes"), comprising a reference electrode, a stimulator electrode and a measuring electrode, thus allowing at least one NCS biopotential signal to be recorded.

[0086] The set of needle-based electrodes 80 can be referred to as a "harness" or "electrode harness" for use with a selected medical monitoring machine, e.g., an EEG machine. Advantageously, each needle-based electrode 80 of the set of needle-based electrodes 80 can include an insertable needle portion 81 that is thin and / or narrow enough to be inserted with substantially zero pain while being rigid and / or sharp enough to not require a separate trocar and / or needle for insertion, while have sufficient surface area to substantially detect the biosignal (optionally via the ‘safety portion 82’ gripped by the clinician during insertion).

[0087] Described herein is a needle-based method that uses at least two needles (i.e., at least two needle-based electrodes 80), or a set of needles (i.e., a set of needle-based electrodes 80) to measure at least one biosignal from a patient.

[0088] The method for measuring at least one biosignal from a patient, comprising the step of: inserting two or more needle-based electrodes 80 each comprising an insertable needle portion 81 configured for insertion into the epidermis 93 or dermis 94. Each of the two or more needle-based electrodes 80 can comprise an adaptor portion electrically coupled its insertable needle portion 81,wherein the two or more needle-based electrodes 80 each conduct a measured biosignal from its insertable needle portion 81 to its adaptor portion 84. The method also comprises electrically coupling each of the two or more needle-based electrodes 80 to a corresponding electrical cable 85 (e.g., each electrical cable 85 is coupled to one needle-based electrodes 80). In this way, an electrical signal corresponding to a biosignal measured by a particular needle-based electrode 80 is provided to the electrical cable 85 coupled to the needle-based electrode 80. In at least one embodiment, each of the two or more needle-based electrodes 80 comprises an adaptor portion 84 for providing an electrical coupling to the one or more electrical cables 85. Each electrical cable 85 is configured to carry the electrical signal corresponding to a measured biosignal to an electronic amplifier or other receiver system configured to record, perform analysis, and / or display the measured biosignal.

[0089] Typically, each needle-based electrodes 80 is inserted into the patient’s skin so that its insertable needle portion 81 is inserted so that the tip 86 of its insertable needle portion 81 is located at a depth (perpendicular to the surface of the patient’s skin) of 12 mm or less, 11 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, 4 mm or less, 3 mm or less, 2 mm or less, 1 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, or 0.1 mm or less from the surface of the patient’s skin.

[0090] Typically, each needle-based electrodes 80 is inserted into the patient’s skin of the subject so that at least 0.02 mm2, at least 0.03 mm2, at least 0.04 mm2, at least 0.05 mm2, at least 0.06 mm2, at least 0.07 mm2, at least 0.08 mm2, at least 0.09 mm2, at least 0.1 mm2, at least 0.11mm2, at least 0.12 mm2, at least 0.13 mm2, at least 0.14 mm2, at least 0.15 mm2, at least 0.16 mm2, at least 0.17 mm2, at least 0.18 mm2, at least 0.19 mm2, at least 0.2 mm2, at least 0.21 mm2, at least 0.22 mm2, at least 0.23 mm2, at least 0.24 mm2, or at least 0.25 mm2of its insertable needle portion 81 is inserted into the patient’s skin.

[0091] Typically, the method involves insertion of an insertable needle portion 81 into the epidermis 93 or the dermis 94 but not beyond the dermis 94 (thus not sub-dermally) such that its tip 86 lies in the epidermis 93 or dermis 94 or “intraepidermally” or “intradermally”. In at least one embodiment, the method includes inserting the insertable needle portion 81 into the epidermis 93 without penetrating the dermis 94. In at least one embodiment, the method includes inserting the insertable needle portion 81 through the epidermis 93 and into the upper region (papillary region) of the dermis 94, without penetrating into the reticular dermis.

[0092] In at least one embodiment, the method includes inserting the insertable needle portion 81 into the patient’s skin at an insertion angle 87 (between the insertable needle portion 81 and the surface of the patient’s skin) that is small as described hereinbefore. The insertion angle 87 maybe substantially less than 45, 40, 35, 30, 25, 20, 18, or 17 degrees, e.g., substantially 20, 18, 17, or 16 degrees. In at least one embodiment, the “intraepidermal or intradermal insertion angle” is 45 degrees or less, 40 degrees or less, 35 degrees or less, 30 degrees or less, 25 degrees or less, 20 degrees or less, 18 degrees or less, 17 degrees or less, 16 degrees or less, 15 degrees or less, 14 degrees or less, 13 degrees or less, 12 degrees or less, 11 degrees or less, 10 degrees or less, or 8 degrees or less.

[0093] As shown in Figure 3, the insertable needle portion 81 can be manually aligned at the insertion angle 87 relative to the surface of the patient’s skin prior to insertion. The insertable needle portion 81 is then inserted into the epidermis 93 and, if applicable, dermis 94, thereby positioning the insertable needle portion 81 at the inserted angle 88 relative to the surface of the patient’s skin (and under the surface of the patient’s skin), as shown in Figure 4. The insertion angle 87 prior to insertion would generally be substantially equal to the inserted angle 88 after insertion; however, in some cases the insertable needle portion 81 can be braced in a particular way by the clinician such that an angle between safety portion 82 (which may be a flexible portion) and the surface of the patient’s skin can change before and after insertion.

[0094] When inserting the insertable needle portion 81, the clinician or other user can, in effect, increase the critical buckling force (Fcr) of the needle-based electrode 80 by gripping the needlebased electrode 80 closer to the insertable needle portion 81 (i.e., closer to the end being inserted into the patient’s skin), thereby bracing the insertable needle portion 81. Advantageously, the overall rigidity of the needle-based electrode 80 can be lower than what would be required without bracing the needle-based electrode 80 when inserting, as the act of bracing may be understood as increasing the effective rigidity of the insertable needle portion 81 in the vicinity of the insertable needle portion 81. A lower rigidity allows for the inserted needle-based electrode 80 to flex which may, as previously described, advantageously decrease or eliminate discomfort for the patient.

[0095] Each needle-based electrode 80 that has been partially inserted into the epidermis 93 and optionally dermis 94 can be referred to as a "recording electrode" because it can be used to measure biosignals via its inserted insertable needle portion 81.

[0096] For ECG, EMG, EOG, NCS, and EEG, measurement is made of the electrical potential (i.e. voltage) between electrode pairs. For EMG, the biosignal originates from muscle tissue and is measured in the dermis 94 or epidermis 93 that is adjacent to or nearby the muscle tissue. The very high input impedance specifications of the biopotential amplifiers means that negligible current flows though the needle-based electrodes 80 and it is the time-varying electrical potential that contains the biological signal. For ECG, EMG, and EOG a minimum of two electrodes (i.e.,a minimum of two insertable needle portions 81) is necessary. For NCS and EEG a minimum of three electrodes (i.e., a minimum of three insertable needle portions 81) is required.

[0097] Although the described embodiments relate to insertion of a needle-based electrode 80 into the epidermis 93 only or into the dermis 94, without extending further (such as into the subdermis 95), it is envisaged that for certain applications, an embodiment can allow for a needlebased electrode 80 configured to insertion through the dermis 94 and into the subdermis 95. For example, this may be useful for EMG measurements.

[0098] According to one or more embodiments, the method includes coupling (e.g., by physically connecting) the one or more needle-based electrodes 80, e.g., using the harness, to electronic inputs, e.g., amplifiers, of the medical machine.

[0099] In at least one embodiment, the method includes connecting a reference electrode (i.e., being an individual needle-based electrode 80) and / or a ground electrode (i.e., being another individual needle-based electrode 80) to the medical machine to provide a reference signal and / or a ground (earth) signal (respectively). The reference and ground signals are relative to the recording electrode(s), for the medical machine.

[0100] In at least one embodiment, the method includes the step of measuring one or more biosignals using the inserted one or more needle-based electrodes 80. The, or each, biosignal is electrically conducted through the conductive core(s) of the one or more inserted needle-based electrodes 80 to the respective adaptor portion(s) 84 for transmission to the medical machine.

[0101] The method may include the medical machine / equipment processing the biosignals from the one or more needle-based electrode 80 to generate medical signals and visual displays, based on the detected biosignals, for diagnosis of the patient.Example Experimental Implementations

[0102] In an experimental implementation, an electroencephalogram (EEG) was acquired with an example set of the needle-based electrodes 80 in a term baby (37 weeks post-menstrual age).

[0103] Thirty-three of the recording electrodes were positioned according to the modified international 10 / 10 electrode placement system at Fpl, Fp2, Fz, F3, F4, F7, F8, FC1, FC2, FC5, FC6, FT9, FT10, Cz, C3, C4, T7, T8, CPI, CP2, CP5, CP6, TP9, TP10, Pz, P3, P4, P7, P8, P9, P10, 01 and 02. The reference electrode was placed at CPz and the ground electrode was placed at FCz. The placement of the electrodes onto the scalp of a neonatal infant is shown in Figure 5 and Figure 6.

[0104] The example set of needle-based electrodes 80 included the insertable needle portions 81 with stainless steel bodies. The example insertable needle portion 81 of each had a length of substantially 10 mm, a circular cross-section along the length of the insertable needle portion 81, a diameter of substantially 120 pm, and taper point tip 86. Adjacent to the insertable needle portion 81 was an example stainless-steel safety portion 82, having length of substantially 20 mm, a circular cross-section along the length of the portion 82, and a diameter of substantially 120 micrometres. The example attachment portion 83 included a soft flat padded covering between each insertable portion 81 and safety portion 82. Adjacent to each safety portion 82 was an example stainless-steel adaptor portion 84, having a length of substantially 10 mm, a circular crosssection along its length and a diameter of substantially 2 pm.

[0105] The example needle-based electrodes 80 were sterilised with ethylene oxide before use.

[0106] The example insertable portions 81 were fully inserted into the epidermis of the scalp, oriented radially out from position Cz. The insertion was achieved by gripping each example safety portion 82 at the end closest to the insertable portion 81, flexing the insertable portion 81 so that the tip 86 was substantially parallel to the surface of the patient’s skin, and advancing the insertable portion 81 with slow constant pressure while gently tensioning the patient’s skin until fully inserted. An expert clinical caregiver acting as an external observer scored the pain on insertion for all thirty-five electrodes as zero using the modified Pain Assessment Tool (mPAT) (O’Sullivan, Rowley, Ellis, Faasse, & Petrie (2016)). The attachment portion 83, which included a non-woven fixation tape, was then attached to the patient’s skin and then further secured with collodion adhesive glue.

[0107] The set of example adaptor portions 84 were connected to customised signal leads, each comprising a wire of 150 cm length configured with female DuPont square connectors that pushed- on onto the electrode connector portions at one end, and industry standard 1.5 mm touch-proof safety sockets to connect to an EEG amplifier at the other. The signal leads were bundled together along their length and secured with tape to minimise the opportunity for electrical noise to be induced in the wires due to electromagnetic fields in the environment. The patient’s head was padded with cotton wool and wrapped with bandage for protection from pressure injury.

[0108] An example EEG was recorded with a direct current (DC)-coupled amplifier from DC- 3500 Hz using the Compumedics Neuvo 64-channel EEGZEP recording system and Profusion EEG (Version 6) acquisition software. The recorded signals were digitised with a sampling rate of 2 kHz and a resolution of 24 bit. The measured impedances for each electrode was substantially <1 kQ

[0109] The resulting scores of pain experienced by the patient on insertion of the needle-based electrodes 80 was zero for all thirty-five electrodes.

[0110] Excerpts of the data acquired from this embodiment are shown in Figures 6 to 14 and are presented as a typical clinical anterior to posterior montage, where traces show fluctuations in voltage over time between adjacent pairs of electrodes, grouped into lines drawn from anterior to posterior aspect of the head. These data have been pre-processed with bandpass filtering at 1-70 Hz (second-order Butterworth filter) with a 50 Hz notch filter (fourth-order Butterworth filter).[OHl] The collection of EEG data having appropriate signal strength to be clinically useful is difficult to achieve without a high quality system. This problem is accentuated in neonatal patients having thick oily skin that is high in keratin. Furthermore, skin abrasion is required to obtain a signal when using surface electrodes in a neonatal patient, which is problematic as neonatal skin is delicate and breaks down. Furthermore, pain associated with deep insertion of standard wider bore needle electrode often requires anaesthesia. In this example, data has been collected from a neonatal patient using the example needle-based electrodes 80. Despite the example needle-based electrodes 80 comprising a very fine insertable needle portion that is inserted so close to the surface of the patient’s skin, it has been possible to observe a range of characteristic features in a normal neonatal EEG that are difficult to achieve without a high quality system. As shown in the figures, it has been possible to observe normal asynchronous discontinuity (in Figure 7), normal background delta brush activity (in Figure 8), excess beta background (in Figure 9), normal eye flutter or nystagmus (in Figure 10), frontal sharp transients (partially left sided), a characteristic neonatal EEG pattern which is normally bilateral at term and unilateral preterm (in Figure 11), a normal awake neonatal trace (low amplitude continuous) (in Figure 12), normal neonatal discontinuity (2 to 4 seconds) (in Figure 13), normal neonatal quiet sleep (in Figure 14) and normal 5-6 Hz central rhythms (in Figure 15).Electrode Mounts

[0112] Figures 16A to 16D show different views of an electrode mount 10 according to one or more embodiments. Figure 16D shows the electrode mount 10 in contact with a patient (specifically the patient’s skin 91). The patient’s skin 91 is omitted from Figures 16A to 16C. The electrode mount 10 comprises a body 20 defining an external patient contact surface (herein, “contact surface”) 21 (the contact surface 21 is visible in the view of Figure 16C). The contact surface 21 is adapted to be affixed to the skin 91 of a patient (e.g., see Figure 16D). The contact surface 21 can be shaped such as to sit substantially flush with the skin 91 of the patient 90 when affixed to the patient 90. In one example, the contact surface 21 can be substantially flat, which may provide for sufficient contact between the skin 91 of the patient 90 and the contact surface 21over substantially the entire area of the contact surface 21 (for example, in cases where the dimensions of the contact surface 21 are relatively small when compared to the curvature of the skin 91 of the patient 90). In another example, the contact surface 21 can have a concave profile (typically, a relatively shallow concave profile) such as to follow natural contours of the skin 91 of the patient 90.

[0113] The electrode mount 10 is configured to receive one or more electrode members 11 (two electrode members I la and 11b are shown in Figures 16A to 16C, only one electrode member I la is visible in Figure 16D). The, or each, electrode member 11 can have a needle-like structure having an insertion end 40 for inserting into the skin 91 of the patient. The one or more electrode members 11 are typically utilised as a component of an electrode for measuring bioelectrical signals of the patient (which may therefore be termed a “medical electrode”). In an embodiment, each electrode member 11 corresponds to a unique electrode. In another embodiment, two or more electrode members 11 are associated with the same electrode (in Figure 16A, the two electrode members I la, 11b are electrically coupled together thereby forming a single electrode). In an embodiment (not shown), there are three or more electrode members 11, at least two electrode members 11 forming a first electrode and a least one other electrode 11 forming a second electrode. Figure 16B shows the same view as Figure 16B, but with the body 20 omitted such as to show the path of the electrode members 11 within the body 20.

[0114] The insertion end 40 of an electrode member 11 ends at a tip 41. An opposite, distal end 43 (most clearly seen in Figure 16D) of the electrode member 11 remains outside of the patient 90 in use. The electrode members 11 are electrically conductive. For example, the electrode member 11 can comprise stainless steel. In at least one embodiment, the electrode member 11 is, or has a similar structure to, a commercially available acupuncture needle. As the electrode members 11 are inserted into the patient’s skin 91, it is typically a requirement that the electrode members 11 be suitably sterilised before use. The electrode member 11 can be configured to have an impedance less than 10 kQ, or between 1 kQ to 5 kQ. In some embodiments, the electrode member 11 can have an impedance that is less than 1 k . It is envisaged that a user (e.g., a medical professional) will have access to a variety of sizes of electrode member 11 to select from. Each different size of electrode member 11 can be associated with its own electrode mount 10 specifically configured for receiving that size. It is also envisaged that an electrode mount 10 can be provided suitable for use with a range of sizes of electrode members 11. In an embodiment, the electrode members 11 are formed from a non-ferromagnetic material. Other suitable materials for forming the electrode members 11 can include one or more of: titanium, platinum, gold, carbon derivatives, and conductive polymers.

[0115] In one or more embodiments, each electrode member 11 corresponds to a needle-based electrode 80 as described with reference to Figures 1 to 4. In at least one embodiment, the electrode mount 10 can correspond (at least in part) to the attachment portion 83 of the needlebased electrode 80. In at least one embodiment, the electrode mount 10 can correspond, at least in part, to the adaptor portion 84 of the needle-based electrode 80. For example, the electrode mount 10 can correspond (at least in part) to both the attachment portion 83 and the adaptor portion 84 of the needle-based electrode 80.

[0116] For the, or each, electrode member 11, the electrode mount 10 comprises a corresponding electrode guide 22. In general, irrespective of the number of received electrode members 11, the operating principle of each electrode guide 22 is the same. The following description therefore refers to a single electrode guide 22 on the understanding that the description is applicable to all electrode guides 22 of embodiments in which the electrode mount 10 comprises two or more electrode guides 22.

[0117] Figure 17 shows an exemplary method for using an electrode mount 10. At step SI 00, the electrode mount 10 is positioned onto and affixed to the skin 91 of the patient. The location of the electrode mount 10 on the skin 91 is dependent on the intended location of a corresponding electrode member 11 on the skin 91. The contact surface 21 of the electrode mount 10 is positioned adjacent the skin 91 of the patient, with the remainder of the body of the electrode mount 10 extending away from the skin 91. The electrode mount 10 can be affixed using a suitable adhesive.

[0118] Next, at step 101, an electrode member 11 is inserted into a distal opening 25 of the electrode mount 10. For example, the electrode member 11 is positioned outside of the electrode mount 10 with its tip 41 facing the distal opening 25 as shown in Figure 18. The user can then insert the tip of the electrode member 11 into the distal opening 25. At step S102, the electrode member 11 is pushed further into the electrode mount 10 until it exits past the contact surface 21 and enters the patient’s skin 91. Once fully inserted, a portion of the electrode member 11 is present within the patient’s skin 91 as shown in Figure 16D.

[0119] The, or each, distal opening 25 can be tapered from a relatively large cross-section to a cross-section commensurate with the size of its electrode guide 22. In this way, when inserting an electrode member 11, the entrance into the electrode mount 10 is relatively large and thereby easier to locate for a user, while ensuring that the electrode member 11 is guided into the electrode guide 22. The relatively smaller cross-section of the electrode guide 22 may otherwise make it relatively difficult for a user to direct into it an electrode member 11.

[0120] Referring back to Figures 16B and 16D, fully inserted electrode members 111, 11b are shown within their corresponding electrode guides 22a, 22b (i.e., within the body 20, which isomitted in order to assist with viewing the internal structure of the electrode mount 10, including the electrode guides 22a, 22b). An electrode guide 22 defines a channel extending between a proximal opening 24 and the distal opening 25. The proximal opening 24 is an opening located near the patient’s skin 91, typically being an opening of the contact surface 21 of the electrode mount 10 and therefore located proximal to the skin 91 of the patient 90 when the electrode mount 10 is affixed to the skin 91. The distal opening 25 is an opening of the body 20 of the electrode mount 10 located away from the contact surface 21 (e.g., a distal opening 25 can be located further from the contact surface 21 and therefore the patient’s skin 91 than its associated proximal opening 24) and therefore distal to the skin 91 of the patient 90 when the electrode mount 10 is affixed to the skin 91. The electrode guide 22 has an internal cross-section complementary to a cross-section of the electrode member 11. The electrode guide 22 should allow for a user to push an electrode member 11 through the body 20 but should otherwise provide a relatively close fit between the body 20 and the electrode member 11.

[0121] The electrode guide 22 is typically configured to ensure that the portion of the electrode member 11 extending out of the proximal opening 24 enters the patient’s skin 91 at a relatively shallow insertion angle a, such as of approximately 5° or less (e.g., see angle a between the contact surface 21a and the insertion end 40a of the electrode member I la as shown in Figure 1C). Optionally, where applicable, the insertion angle a can correspond to, and take the value of, the insertion angle 87 of the embodiments of Figures 1 to 4. The portion of an electrode member 11 located within the patient’s skin 91 can be termed the “inserted portion” of that electrode member 11. As an example, the inserted portion can comprise approximately 5 mm of the electrode member 11 (i.e., measured from the tip 41 of the electrode member 11). In order to ensure consistency in the insertion angle a between uses of the electrode mount 10, the electrode guide 22 comprises an alignment length 26 being a length of the electrode guide 22 starting at the proximal opening 24 and extending towards the distal opening 25. The alignment length 26 can correspond to a substantially straight portion of the electrode guide 22. Optionally, the alignment length 26 is not exactly straight but includes a shallow downwards curvature (e.g., as shown in Figure 16D). Generally, the purpose of the alignment length 26 is to minimise or eliminate the risk of significant variance in the angle at which electrode members 11 enter the patient’ s skin 91. In particular, it can be desirable to avoid the insertion angle a being larger than a predefined maximum, which could lead to an electrode member 11 entering unnecessarily deeply into the patient’s skin 91. The particular shape and configuration of the alignment length 26, as well as the predefined maximum for angle a, can be dependent on the particular use case and can therefore constitute design parameters.

[0122] In one or more embodiments, for example as shown in Figure 16D, the electrode guide 22 is configured to cause a substantial bending of an inserted electrode member 11 between the proximal opening 24 and the distal opening 25. Such embodiments may be suitable where the electrode member 11 is sufficiently flexible to allow for said bending. The electrode guide 22 therefore comprises a bend 27 (corresponding to a portion of the electrode guide 22 between the distal opening 25 and the alignment length 26) shaped to cause an inserted electrode member 11 to bend. The bend 27 should be sufficiently long to enable bending of the electrode member 11 without substantially inhibiting insertion of the electrode member 11 or risking damage to the electrode member 11. An advantage of said embodiments may be that the electrode member 11 can be inserted into the electrode mount 11 at an angle larger than a, while still ensuring that the electrode member 11 enters the skin 91 of the patient 90 at the predefined insertion angle a. In practice, this may improve the useability of the electrode mount 10 by providing a more convenient direction for the user to insert the electrode member 11 into the electrode mount 10.

[0123] An electrode guide 22 may advantageously have the effect of bracing the electrode member 11 during insertion, thereby enabling an electrode member 11 to be inserted into the patient’s skin which would otherwise (e.g., absent the use of an electrode mount 10) be insufficiently rigid to insert into the patient’s skin. Therefore, an advantage of an electrode mount 10 comprising one or more electrode guides 22 may be a reduced burden on the clinician or other user, as careful gripping of the electrode members 11 to ensure bracing is not required (said bracing being effectively provided by the electrode guide(s) 22).

[0124] Depending on the embodiment, a particular electrode member 11 can terminate at its distal end 43 at a handle 44. In some of the figures, a relatively short handle 44 is shown compared to other figures (e.g., compare Figure 16A showing short handles 44a, 44b and Figure 16C showing long handles 44a, 44b). Generally, the length of the handles 44 shown in the various figures can be interchanged. However, it may be preferred to include sufficiently long handles 44 (that is, in a direction parallel to the length of its electrode member 11) to enable a user to grip the handle 44. Once inserted, longer handles 44 can be cut to reduce the risk of the handles 44 being accidentally caught or tugged (this may be appropriate in cases where the electrode members 11 are intended for single use). In this way, a user can manipulate an electrode member 11 (e.g., for insertion into and removal from an electrode mount 10) by only coming into contact with its handle 44. Handles 44 are therefore typically of wider diameter than their associated electrode members 11, as shown. An advantage of such handles 44 can be that they are blocked from entering into the electrode guides 22, thereby limiting the ultimate depth at which the electrode member 11 can enter into the patient’s skin 91 (i.e., an electrode member 11 cannot extend furtherfrom the electrode mount 10 than as shown in the various figures in which the corresponding handle 44 is abutting the body 20 of the electrode mount 10). Thus, the maximum depth of the electrode members 11 into the patient’s skin 91 is thereby controlled as well as the insertion angle a due to the configuration of the electrode guides 22. The handles 44 are optionally formed from an electrically insulating material.

[0125] As a general principle, the sensitivity of an electrode member 11 for detecting bioelectrical signals is proportional to the surface area of the inserted portion of the electrode member 11 (i.e., the surface area of the portion of the electrode member 11 in contact with the patient’s skin 91). The surface area can depend upon the length of the inserted portion (i.e., the depth of the electrode member 11 within the patient’s skin 91) as well as the cross-sectional size of the electrode member 11. For example, for a cylindrical electrode member 11, the surface area is proportional to the product of the diameter of the cylinder and its length within the patient’s skin 91). An advantage of embodiments utilising electrode members 11 having associated handles 44 or other means to limit or control the length of the inserted portion of the electrode members 44 is a corresponding control of the

[0126] Referring to Figure 18, the electrode mount 10 according to an embodiment is configured to receive two electrode members I la, 11b. Figure 18 shows two electrode members I la, 11b ready for insertion into the electrode mount 10. The electrode mount 10 comprises, for each electrode member 11, 1 lb, a distal opening 25a, 24b for receiving an electrode member I la, 1 lb (e.g., in the present embodiment, there are two distal openings 24a, 24b and two electrode members I la, 11b).

[0127] Referring back to Figure 17, at step S103, bioelectrical signal measurements are obtained from the electrode(s) 11 inserted into the electrode mount 10. Typically, steps S101-S102 of Figure 17 are repeated for each electrode member 11 in cases where the electrode mount 10 is configured for receiving multiple electrode members 11 (i.e., typically for multiple electrode members 11, these are inserted in sequence as opposed to simultaneously, for example with reference to Figures 16A and 16C, electrode 1 la can be inserted into electrode guide 22a before electrode 1 lb is inserted into electrode guide 22b).

[0128] In order to obtain bioelectrical signal measurements, the (or each) electrode member 11 is electrically coupled to the relevant measurement apparatus (e.g., EEG, ECG, etc.). Typically, this is via an associated electrically conductive lead 12 (which, depending on the embodiment, may correspond to electrical cable 85 as described in reference to the embodiments of Figures 1 to 4). In embodiment utilising two or more electrode members 11 for a single electrode, anelectrical connection can be made between the two or more electrode members 11 at the electrode mount 10 or at the lead 12.

[0129] In one or more embodiments, for example with reference to Figures 19A and 19B, an end of the, or each, lead 12 is electrically and physically coupled to a lead connector 55 of the electrode mount 10 (in the specific example of Figure 19A, there are two lead connectors 55a, 55b, one for each of two electrode members I la, 1 lb). The end of the lead 12 can be permanently electrically and physically coupled to the lead connector 55. Alternatively, the lead connector 55 comprises a lead attachment mechanism 56 enabling a user to attach a lead 12 to the lead connector 55 as required (and remove an attached lead 12 when required).

[0130] The lead connector 55 provides an electrically conductive coupling between a lead 12 and one or more inserted electrode members 11 (depending on the embodiment). Referring to Figure 19B, the lead connector 55 according to an embodiment extends downwards to the electrode guide 22 and comprises an electrically conductive material such as stainless steel or copper. In use, the lead connector 55 is in physical contact with an electrically conductive portion of an inserted electrode member 11 and thereby forms an electrically conductive path between the electrode member 11 and the lead 12. Therefore, in Figures 19A and 19B, before insertion of an electrode member 11 into the electrode mount 10, the electrode member 1116a is not electrically coupled to the lead 12. Advantageously, embodiments such as that of Figures 19A and 19B may enable the use of existing needles (such as acupuncture needles) as the electrodes without modification of the needles (e.g., these embodiments do not require a lead 12 to be physically coupled to each electrode member 11 before use). An advantage may be that, if required, an electrode mount 10 can be left affixed to a patient 90 and reused, with different electrode members 11 utilised per use.

[0131] In an embodiment, a capacitor (not shown) is provided in series between the one or more electrode members 11 of a single electrode and the respective lead 12. The purpose of the capacitor is to form part of a passive high pass RC filter (in combination with the resistance of the one or more electrode members 11 and the input impedance of an electrical amplifier (the amplifier is coupled to the one or more electrode members 11 via lead 12). The capacitor is selected to pass the expected frequencies of the bioelectrical signal while overcoming half-cell potentials that develop an offset potential exceeding the input potential of the amplifier. Advantageously, the inclusion of a capacitor as a component of the electrode mount 10 may allow for the use of leads 12 that themselves do not require a capacitor).

[0132] In another embodiment, the one or more electrode members 11 are capacitively coupled to the patient. For example, each electrode member 11 can comprise an insulating coatingsurrounding a conductive inner portion (at least the portion of the electrode member 11 intended for insertion into the skin 91), such as to electrically isolate the conductive inner portion from the patient. Biosignals can still be detected through the capacitive coupling and advantageously the inherent capacitance can be utilised as the capacitor of the high pass RC filter. Therefore, advantageously, a separate capacitor may not be required.

[0133] In an embodiment, the lead connector 55 comprises a controllable engagement means for engaging with an inserted electrode member 11, the engagement means having an engaged configuration, in which movement of an inserted electrode member 11 with respect to the channel 23 is inhibited, and a disengaged configuration, in which movement of an inserted electrode member 11 is not inhibited. In the example of Figures 19A and 19B, the engagement means comprises a screw 57 located above the electrode guide 22 (i.e., on an opposite side of the electrode guide 22 to the contact surface 21) which when turned in a first direction moves downwards (i.e., towards the electrode guide 22). The screw 57 is therefore moveable, via rotation in the first direction, to the engaged configuration in which the screw 57 presses against an inserted electrode member 11, thereby providing a friction engagement with the inserted electrode member 11 which will inhibit movement of the electrode member 11 with respect to the electrode guide 22. The screw 57 is also moveable, via rotation in a second direction opposite to the first direction, away from an inserted electrode member 11, thereby moving the screw 57 to the disengaged position. Typically, the screw 57 is electrically conductive and, when in the engaged position, provides at least a portion of the conductive path between an inserted electrode member 11 and the lead 12. Advantageously, the engagement means allows for an inserted electrode member 11 to be secured against further movement, which may minimise or eliminate the risk of the electrode member 11 inadvertently losing contact with the patient’s skin 91 or inadvertently being pushed further into the skin 91 than intended.

[0134] In one or more embodiments, for example with reference to Figures 20A and 20B, the one or more electrode members 11 is permanently physically and electrically coupled to an end of a lead 12. In the example shown, the electrode mount 10 is configured for receiving two electrode members I la, 11b. The two electrode members 11 correspond to a single electrode (i.e., the two electrode members 11 are electrically coupled to one another). In the embodiment shown, the lead 12is electrically coupled to the electrode members I la, 12b within an electrode housing 50. In other embodiments, an electrode housing 50 can be provided associated with a single electrode member 11 or three or more electrode members 11. It should be noted that one electrode member 1 la is visible in these figures, it is understood that a second electrode member 1 lb is also present on an opposite side of the electrode housing 50 (i.e., as indicated with dotted lines). Theelectrode housing 50 can be understood as also having a similar role to that of the previously described handles 44, such that separate handles 44 are not utilised in Figures 5A and 5B. That is, the electrode housing 50 can be understood as also being a handle 44. In an embodiment in which an electrode member 11 corresponds to a needle-based electrode 80, the electrode housing 50 can correspond to the adaptor portion 108.

[0135] The electrode housing 50 can be relatively rigid and sized to allow for a user to more easily grip the electrode housing 50 when compared to the one or more electrode members I la, 1 lb (e.g., grip can be improved by having a cross-section of the electrode housing 50 substantially larger than a cross-section of the one or more electrode members 11). Advantageously, the user can therefore be enabled to push (and pull) on the electrode housing 50 in order to effect insertion (and extraction) of the electrode member 11 into the electrode mount 10. Such an electrode housing 50 may also advantageously protect the electrical contact between the electrode member 11 and the end of the lead 12 against damage. The electrode housing 50 can be electrically insulating. An electrode member 11 is coupled to the lead 12 at its distal end 43. Therefore, the distal end 43 of an electrode member 11 can be located within the electrode housing 50 in which the end of the lead 12 is also located (in Figures 20A and 20B, the physical and electrical coupling between the distal end 43a of electrode member I la and the lead 12 so not explicitly shown but is understood to be located within the electrode housing 50).

[0136] Optionally, as shown in Figures 20A and 20B, the body 20 of the electrode mount 10 comprises a mount engagement structure 51 which has a complementary profile with respect to a housing engagement structure 52 of the electrode housing 50. In the example shown, the mount engagement structure 51 corresponds to a shaped recess within the body 20, with first and second distal openings 25a, 25b (of respective first and second electrode guides 22a, 22b (one electrode guide 22a is shown in Figure 20B)) located within the recess. Also as shown, the housing engagement structure 52 corresponds to a complementary shaped protrusion of the electrode housing 50. In order to fully insert the electrode members I la, 11b into the electrode mount 10, the electrode housing 50 must have a matching housing engagement structure 52 correctly matching the mount engagement structure 51 of the particular electrode mount 10.

[0137] Typically, the electrode mounts 10 are affixed to the skin 91 of the patient 90 using a suitable adhesive.

[0138] Figure 21 shows an electrode mount 10 according to another embodiment, which can be understood as a variation to those of Figures 16A-16D, 18, and 19A-19B. The lead 12 terminates at a conductive structure corresponding to a component of the lead attachment mechanism 56. The lead attachment mechanism 56 comprises one or more tabs 58 (in the exampleshown, there are two tabs 58a, 58b; generally, there is a tab 58 for each electrode guide 22 of the electrode mount 10). A tab 58 can be relatively flat (e.g., defining a plane approximately parallel with the contact surface 21) and positioned such that at least a portion of the tab 58 overlays a portion of its associated electrode guide 22. In the overlaying portion, the tab 58 can be brought into physical and electrical contact with an inserted electrode member 11 by pressing the tab 58 downwards (i.e., towards the contact surface 21). A screw (such as screw 57 of Figure 19B, but not shown in Figure 21) can be used to selectively press the tab 58 downwards onto an inserted electrode member 11. When pressed down onto an inserted electrode member 11 (e.g., by its associated screw 57), the lead attachment mechanism 56 is in the engaged configuration and the tab 58 acts to both secure the electrode 10 in place (i.e., through a friction engagement) and to ensure an electrical connection to between the lead 12 and the electrode member 11. When not pressed down onto an inserted electrode member 11, the lead attachment mechanism 56 is in the disengaged configuration. In the figure, the tabs 58 and attachment mechanism 56 are understood to be internal to the body 20; the figure represents a simplified cross-section of the body 20. The

[0139] Figure 22 shows a variation to the embodiment shown in Figure 21. The lead attachment mechanism 56 comprises an electrically conductive member defining a roughly U- shaped cross-section as shown. The top portion 59 of the lead attachment mechanism 56 defines a tongue which is located on the top of the electrode mount 10 (or at least, away from the contact surface 21). In the example shown, the top portion 59 of the lead attachment mechanism 56 extends up and away from the body 20 of the electrode mount 10. The top portion 59 of the lead attachment mechanism 56 is physically and electrically coupled to an end of the lead 12. The bottom portion 60 of the lead attachment mechanism 56 splits into to tabs 58a, 58b (only tab 58a is shown), which can be arranged roughly parallel to and spaced apart from the top portion 59 of the lead attachment mechanism 56. Each tab 58a, 58b is pressed via action of an associated screw 57a, 57b (on screw 57a is shown) in a similar manner as described with respect to Figure 21. When pressed against an electrode member 11, the lead attachment mechanism 56 is in the engaged configuration. An advantage of the embodiment of Figure 22 may be that the location at which the lead 12 is coupled to the lead attachment mechanism 56 is at or near the top of the body 20 (e.g., located above the body 20) and therefore maximally distant from the patient’s skin 91, while enabling the lead attachment mechanism 56 to press against the one or more electrode members 11 close to the contact surface 21, thereby facilitating a shallow insertion angle a as shown.

[0140] In some cases, the embodiments of Figure 21 and Figure 22 may provide an advantage in that the lead 12 and electrode member 11 are effectively in direct electrical contact (as the oneor more tabs 58 are effectively permanently electrically coupled to the lead 12), rather than indirect contact as via the screw 58 (which could therefore, at least in principle, be electrically insulative) of Figure 19B.

[0141] Other means are envisaged for causing a pressing forced to be applied to the tab 58 (i.e., instead of a screw 57). For example, a lever-based locking mechanism can be utilised to provide the pressing force, where the lever-based locking mechanism is lockable at a pressed position through manipulation by the user. The pressed position can correspond to the engaged configuration of the lead attachment mechanism 56. In a variation, a lever-based locking mechanism is provided in which the mechanism is biased towards a pressed position, such that user actuation is required to move the lever-based locking mechanism into an unlocked position. For example, user actuation may be a lifting force to unlock the lever-based locking mechanism, and little or no user provided force may be required to return the lever-based mechanism to the pressed (i.e., locked) position due to the inherent bias. Advantageously, such a lever-based locking mechanism may reduce or avoid a downwards pressing force being applied to the patient’s skin 91, which may advantageously reduce or eliminate discomfort to the patient when locking the electrode member 11 in place, In some embodiments, the means can be insulating (e.g., where it is not required to form a part of the electrical connection between the electrode member 11 and the lead 12).

[0142] Referring back to Figure 17, once the bioelectrical signal measurements are obtained, the electrode member 11 is removed from the patient’s skin 91 and the electrode mount 10, at step SI 04. Typically, this is a reverse process of steps S101-S102. In embodiments in which the electrode member 11 is secured in place, it is first unsecured. An unsecured electrode member 11 can be removed by pulling it in the opposite direction to which it was inserted.

[0143] Once the, or all, electrode members 11 are removed from a particular electrode mount 10, it can be removed from the patient at step SI 05. Where an adhesive is utilised for affixing the electrode mount 10, a suitable solvent can be applied at step SI 05 to assist with removal of the electrode mount 10.

[0144] It should be noted that an electrode mount 10 can be left on the patient’s skin 91 between instances in which bioelectrical signal measurements are obtained, although the electrode members 11 themselves are removed between instances. Therefore, steps S101-104 can be repeated one or more times before step SI 05. This may advantageously reduce the time for preparing a patient for subsequent bioelectrical signal measurements and reduce the discomfort for the patient.

[0145] Referring to Figure 23, according to one or more embodiments, a separate adhesive element 19 is utilised to facilitate affixing the electrode mount 10 to the patient’s skin 91 (in this case, the specific illustration shown in Figure 23 is related to the embodiment show in in Figures 20A and 20B). The adhesive element 19 comprises a patient-side adhesive surface 30 for adhering to the patient’s skin 91 and an opposite mount-side adhesive surface 31 for adhering to the contact surface 21 of the electrode mount 10. The patient-side adhesive surface 30 comprises a suitable adhesive for adhering to skin 91, optionally in the form of an adhesive layer (not shown) applied to the patient-side adhesive surface 30. The mount-side adhesive layer 31 comprises a suitable adhesive for adhering to the contact surface 21, optionally in the form of an adhesive layer (not shown) applied to the patient-side adhesive surface 30. In one example, the adhesive element 19 is first attached to the contact surface 21 of the electrode mount 10 (e.g., by pressing its mount-side adhesive surface 31 to the contact surface 21). Then, the combined adhesive element 19 and electrode mount 10 is positioned on the patient’s skin 91, such that the adhesive patient-side adhesive surface 30 is put into contact with the patient’s skin 91, causing the adhesive element 19 and thereby the electrode mount 10 to be affixed to the patient’s skin 91. Another option can be first affixing the adhesive element 19 to the patient’s skin 91 and then affixing the contact surface 21 of the electrode mount 10 to the adhesive element 19.

[0146] As shown, the adhesive element 19 can comprise a surface area larger than that of the contact surface 21, such that portions of the adhesive element 19 are accessible by a user (e.g., for removal of the adhesive element 19 from the patient’s skin 91). Also as shown, the adhesive element 19 can comprise one or more apertures 32 (in the example shown, there are two apertures 32a, 32b, one for each of the two electrode members I la, 11b). An aperture 32 allows an electrode member 11 to move from the electrode mount 10 to the patient’s skin 91 without interfering with the movement of the electrode member 11. An aperture 32 can be larger (in both a longitudinal direction and transverse direction) than the electrode members 11, such that there can be some margin of error allowed in aligning the aperture 32 with a corresponding proximal opening 24 of the contact surface 21.

[0147] In an embodiment, the adhesive of the patient-side adhesive surface 30 is the same as the adhesive of the mount-side adhesive surface 31. An advantage of this embodiment may be, for example, that the adhesive element 19 can be utilised in either orientation such that, in effect, the patient-side adhesive surface 30 and the mount-side adhesive surface 31 are defined according to the orientation of the adhesive element 19. In another embodiment, the adhesive of the patientside adhesive surface 30 is different to the adhesive of the mount-side adhesive surface 31. An advantage of this embodiment may be, for example, that the patient-side adhesive surface 30comprises an adhesive particularly suited for bonding with skin 91 whereas the mount-side adhesive surface 31 comprises an adhesive particular suited for bonding with the contact surface 21.

[0148] Alternatively, in one or more embodiments, such as with reference to Figure 21, an adhesive strip 29 is provided directly onto the contact surface 21 of the electrode mount 10, such that the contact surface 21 is brought into direct contact with the patient’s skin 91 (i.e., instead of via an adhesive element 19). For example, in Figure 21 a cut-out portion of adhesive tape (for example, 3M™ Medical Transfer Adhesive 4075 (available at https: / / www.3m.eom / 3M / en_US / p / d / vl00849004 / ) has been applied to the contact surface 21 of the electrode mount 10. In some examples, an adhesive strip 29 such as 3M™ Medical Transfer Adhesive 4075 can be applied across the contact surface 21 such as to cover the one or more proximal openings 24 of the one or more electrode guides 22. Advantageously, assuming that the adhesive strip 29 is sufficiently thin to be easily pierced by the one or more electrode members 11, the adhesive strip 29 may not require the presence of one or more apertures 32 such as utilised in the adhesive element 29 of Figure 23.

[0149] In one or more embodiments, the adhesive strip 29 of Figure 21 or the patient-side adhesive surface 30 of Figure 23 is provided with a non-adhesive strip (not shown). Relevantly, the non-adhesive strip provides a barrier between the adhesive strip 29 or the patient-side adhesive surface 30 and the patient’s skin 91; without removal of the non-adhesive strip, the electrode mount 10 cannot be affixed to the patient’ s skin 91. In one or more embodiments, the non-adhesive strip comprises a contact portion directly adjacent the adhesive strip 29 or the patient-side adhesive surface 30 and an extended portion not in contact with the adhesive strip 29 or the patient-side adhesive surface 30. The extended portion can be arranged such that, when pulled, the entire non- adhesive strip can be removed from the adhesive strip 29 or the patient-side adhesive surface 30, thereby allowing for direct contact between the adhesive strip 29 or the patient-side adhesive surface 30 and the patient’s skin 91. For example, the electrode mount 10 can be positioned on the patient’s skin 91 at its intended location with the non-adhesive strip in place. Once the electrode mount 10 is correctly positioned, the non-adhesive strip can be removed while the electrode mount 10 remains in place, by pulling on the extended portion of the non-adhesive strip. For example, the extended portion of the non-adhesive strip can be effectively folded back and under the contact portion of the non-adhesive strip, with its end extending past the contact portion and thereby available to be gripped and pulled by a user.

[0150] Figures 24A and 24B show four electrode mounts 10a- lOd positioned on a patient’s skin 91 (specifically, on the head of the patient). The electrode mounts 10a- lOd are of the typedescribed with reference to Figure 19A. In Figure 24A, the electrode mounts 10a- lOd have been affixed to the patient’s skin 91 (e.g., corresponding to step S100) and the various electrode members 1 la-1 Ih have been inserted. As can be seen, the electrode members 1 la-1 Ih include handles 44a-44h which are the only visible component outside of the electrode mounts lOa-lOd. In Figure 24B, the handles 44a-44h have been cut at their base, such as to minimise the extent of the handles 44a-44h outside of the electrode mounts 10a- lOd. Although co-labelled with the handles 44a-44h in the figures, the electrode members 1 la-1 Ih themselves are not visible. As can be seen, the electrode mounts lOa-lOd provide a mechanism for assisting with accurate locating and insertion of the corresponding electrode members 1 la-1 Ih.

[0151] Figure 25 shows an applicator tool (“applicator”) 13 configured to assist with positioning and affixing the electrode mounts 10 to the patient’s skin. The applicator 13 comprises an applicator body 70 which is configured to be held and manipulated by a user. Extending from the applicator body 70 are two parallel applicator legs 71a, 71b. Both applicator legs 71a, 71b terminate a distance from the applicator body 70. The terminal ends of both applicator legs 71a, 71b comprise a connection structure for allowing the applicator legs 71a, 71b to be connected to the electrode mount 10. With reference to Figure 16C, the electrode mount 10 comprises two complementary applicator receiving structures 72 to the connection structures such that the two applicator legs 71a, 71b can be connected to an electrode mount 10 by co-locating the two connection structures with the respective applicator receiving structures 72.

[0152] In the particular case of Figure 16C, applicator receiving structures 72 correspond to an L-shaped channel in each side of the body 20 of the electrode mount 10 (in Figure IB, one L- shaped channel 72a is visible). Therefore, the terminal ends of the two applicator legs 71a, 71b comprise L-shaped protrusions extending inwards (i.e., towards the other applicator leg 71a, 71b in each case) (these are not shown in the figure). The applicator legs 71a, 71b in each case are sufficiently resiliently flexible to allow the terminal ends of the applicator legs 71a, 71b to be spread apart (e.g., via manipulation by a user), such that the connection structures can be moved into and away from engagement with the two applicator receiving structures 72, while returning to a substantially parallel configuration after the user completes attachment or removal of the applicator 13 from a particular electrode mount 10. The use of L-shaped channels and L-shaped protrusions may advantageously ensure that the electrode mount 10 is held securely by the applicator 13, in particular restricting rotation of the electrode mount 10 with respect to the applicator legs 71a, 71b. It is anticipated that other configurations may be utilised to achieve the same effect, such as the use of square-shaped, triangle-shaped, and other shapes of the applicator receiving structures 72 and the protrusions. It is also anticipated that applicator receivingstructures 72 may correspond to protrusions rather than channels, with complementary structures on the applicator legs 71a, 71b.

[0153] Advantageously, the applicator 13 may assist with positioning and affixing electrode mounts 10 to the patient’s skin 91 by offering a more easily gripped and manipulated structure (i.e., the applicator body 70) for the user. Figure 25 shows the applicator 13 attached to an electrode mount 10a, with three other electrode mounts lOb-lOd already affixed to the patient’s skin. Notably, one applicator 13 can be reused for multiple electrode mounts 10 by selectively attaching it to and removing it from particular electrode mounts 10. The applicator 13 can be formed from a plastic.

[0154] Referring to Figure 26, according to an embodiment, a lead 12 is physically and electrically coupled to the electrode mount 10 via the applicator receiving structures 72 (e.g., as shown in Figure 25). In the figure, the body 20 of the electrode mount 10 is omitted to enable visibility of the internal (i.e., within the body 20) lead connector 55. The lead connector 55 provides an electrical coupling to inserted electrode members I la, 1 lb.

[0155] The lead 12 terminates at a lead connector 61. The lead connector 61 comprises two lead connector legs 62a, 62b, which are similar to the applicator legs 71a, 71b described with reference to Figure 25. The two lead connector legs 62a, 62b are parallel to one another and spaced apart, and include L-shaped lead connector protrusions 63a, 63b having the same profile as the L-shaped protrusions of the applicator 13 of Figure 25. However, the lead connector protrusions 63a, 63b also comprise respective electrical contacts 64 (in the figure, one electrical contact 64a is visible). These contacts are electrically coupled to the lead 12 via electrical wires (not shown) within the body of the lead connector 61.

[0156] When the lead connector 61 is attached to the electrode mount 10, the electrical contacts 64a, 64b are electrically coupled to the internal lead connector 55 (e.g., an aperture can be provided within each applicator receiving structure 72 exposing the internal lead connector 55 to enable a physical contact to be made between the electrical contacts 64a, 64b and the lead connector 55). In this way, the applicator receiving structures 72 can correspond to a similar feature to the lead attachment mechanism 56 of Figures 21-22.

[0157] Several embodiments of an electrode mount 10 as described herein comprise a body 20 including two or more roughly parallel (“aligned”) extending feet 33 (two feet 33 are expressly labelled in Figure 21, which is taken as an illustrative example of the concept). The two feet 33a, 33b shown in Figure 21 extend outwards from a common portion of the body 20. In the applicable embodiments shown herein, the two or more feet 33 can comprise the portion of the contact surface 21. There can be a foot 33 for at least one and preferably each electrode guide 26, suchthat at least a portion of the electrode guide 26 is within its corresponding foot 33. For example, a foot 33 can comprise the proximal opening 24 of a corresponding electrode guide 26. There can be at least one foot 33 not associated with an electrode guide 26 and therefore not comprising a proximal opening 24.

[0158] Two adjacent feet 33a, 33b can provide an advantage when affixing the electrode mount 10 to the patient’s skin 91. When placing the electrode mount 10 on the patient’s skin 91, the electrode mount 10 can be moved forward (that is, pushed in a direction of the ends of the feet 33a, 33b indicated by the arrow labelled “L” in Figure 21). The inside edges of the two adjacent feet 33a, 33b are shaped to collect hair that may be present on the patient’s skin 91 and to direct it towards central channel 34 (being a vertical channel located where the inside edges of the feet 33a, 33b meet), an effect which may be similar to the action of tines of a comb. Advantageously, the collected hair is moved away from the contact surface 21, thereby reducing or eliminating the amount of hair present between the contact surface 21 and the patient’s skin 91, which can improve the adhesion of the electrode mount 10 to the patient’s skin 91.

[0159] Optionally, a liquid adhesive can be applied to the channel 34 after the hair has been collected at the channel. The collected hair can thereby be affixed to the body 20 of the electrode mount 10 which may advantageously provide additional adhesion of the electrode mount 10 to the patient.

[0160] In an embodiment in which a plurality of electrode mounts 10 are provided, each electrode mount 10 can be visually distinguished (e.g., using colour coding) to assist a clinician or other user with positioning electrode members 11 at the correct locations on the patient’s skin 91. For example, each electrode member 11 can also be colour coded, such that a clinician or other user can visually determine the correct pairing of electrode member 11 and electrode mount 10.Use of Electrode Mounts and Magnetic Resonance Imaging (MRI)

[0161] In one or more embodiments, the electrode mount 10 is configured such that it may be present on a patient’s skin 91 during an MRI scan. Portions of the electrode mount 10 which are not required to be electrically conductive can be formed from a suitable material such as plastic or a ceramic, which is selected such as to not have an MRI signal artefact. Electrically conductive portions, such as the lead attachment mechanism 56 (where applicable), can be formed from a suitably selected conductor (e.g., copper, brass, carbon derivatives, and polymers) which also induce no MRI signal artefact.

[0162] It may not be suitable to retain one or more electrode members 11 within the electrode mount 10 during the MRI scan. However, these are easily removable in preparation for the MRIscan without affecting the position of the electrode mount 10. Therefore, the one or more electrode members 11 can be returned to the electrode mount 10 at some time after the MRI scan (i.e., when needed).

[0163] It may also be the case that certain electrode members 11 are safe to be retained during an MRI scan. For example, there is some evidence in the literature that acupuncture needles present in the body during MRI are safe, they do not cause burns, discomfort or signal artefacts. Also, it is anticipated that the electrode members 11 can be formed using non-ferromagnetic material (e.g., titanium, platinum, gold, carbon derivatives, polymers, etc) which do not interact magnetically with the MRI.

[0164] In any event, the electrode mount 10 can be arranged to ensure that no electrically conductive element is present in contact with the patient’ s skin 91 , which may advantageously also ensure that these elements cannot cause burns, discomfort or signal artefacts.Experimental Results

[0165] Figures 27 A and 27B show preliminary results related to use of electrode mounts 10 when making EEG measurements. Figure 27A shows an electrode mount 10 affixed to a patient (the patient’s skin 91 being partially obscured by the patient’s hair). Two electrode members I la, 11b are inserted into the patient’s skin 91 (note that only the respective handles 44a, 44b are visible). The two electrode members I la, 11b formed single electrode, and are therefore coupled to a common lead 12. Figure 27B shows EEG signal data 92a, 92b from two separate electrodes (i.e., associated with two distinct electrode mounts 10 — although only one is shown in Figure 27A, several were attached to the patient). Although preliminary, the resulting EEG signal data 92a, 92b is as expected.

[0166] Further modifications can be made without departing from the spirit and scope of the specification.

Claims

Claims:

1. A needle-based electrode for measuring at least one biosignal from a patient, comprising: an insertable needle portion comprising a needle tip configured for insertion into the patient’ s skin; and an adaptor portion electrically coupled to the insertable needle portion and configured to electrically couple to one or more electrical cables, wherein the needle-based electrode is electrically conductive to thereby enable measurement of the at least one biosignal.

2. The needle-based electrode of claim 1, further comprising a safety portion mechanically and electrically coupled to and axially aligned with the insertable needle portion to conduct an insertion force along the safety portion to the insertable needle portion, wherein the safety portion is configured to buckle when at least a pre-selected axial force is applied axially along the safety portion.

3. The needle-based electrode of claim 2, wherein the insertable needle portion is more rigid longitudinally than the safety portion.

4. The needle-based electrode of any one of claims 1 to 3, further comprising an attachment portion mechanically coupled to the insertable needle portion, wherein the attachment portion is configured to be attached to the patient’s skin.

5. The needle-based electrode of claim 4, wherein the attachment portion is configured to be attached to the patient’s skin by way of a non-woven fixation tape, an adhesive sheet, or an adhesive bandage holding the attachment portion to the skin.

6. The needle-based electrode of claim 4 or 5, wherein the insertable needle portion is more rigid longitudinally than the attachment portion.

7. The needle-based electrode of any one of claims 1 to 6, wherein the insertable needle portion includes one or more coatings that: reduce friction on insertion of the insertable needle portion into the skin; and / or tailor the half-cell potential or the impedance between the insertable needle portion and the tissue of the patient once inserted.

8. The needle-based electrode of any one of claims 1 to 7, configured to have an electrical impedance less than 10 k , or between 1 kQ to 5 kQ, or less than 1 kQ.

9. The needle-based electrode of any one of claims 1 to 8, wherein the insertable needle portion comprises a circular cross-section.

10. The needle-based electrode of any one of claims 1 to 8, wherein the insertable needle portion comprises a non-circular cross-section having a long axis and a short axis, and wherein the cross-section is symmetric about either one or both of the long axis and the short axis.

11. The needle-based electrode of claim 9 or claim 10, wherein the insertable needle portion has a diameter or longest axis of 300 pm or less.

12. The needle-based electrode of any one of claims 1 to 11, wherein, in use, the insertable needle portion is inserted into the skin at an insertion angle between the insertable needle portion and the skin, wherein the insertion angle is selected to be 45 degrees or less.

13. The needle-based electrode of any one of claims 1 to 12, wherein the insertable needle portion is at least partially flexible such that the insertable needle portion, when inserted into the patient’s skin, can flex in and with the patient’s skin.

14. The needle-based electrode of claim 13, wherein the insertable needle portion has a Young’s Modulus (E) of less than between 25 and 260 kPa.

15. A set of needle-based electrodes, each being the needle-based electrode of any one of claims 1 to 14.

16. A needle-based method that uses the set of the needle-based electrodes of claim 15 to measure at least one biosignal from a patient.

17. The needle-based method of claim 16, including inserting the insertable needle portion into the patient’s skin at an insertion angle such that a substantial length of the insertable needle portion lies within the patient’s skin once the insertable needle portion has been fully inserted.

18. An electrode mount comprising a body having a contact surface for positioning on a patient’s skin, wherein the body comprises one or more electrode guides for facilitating insertion of an electrode member into the patient’s skin at a predefined angle when the contact surface is positioned on the patient’s skin.

19. The electrode mount of claim 18, comprising two or more electrode guides.

20. The electrode mount of claim 18 or claim 19, wherein the one or more electrode guides each define a channel and have a proximal opening and a distal opening, wherein each electrode guide is configured to guide an electrode member inserted into its distal opening towards its proximal opening, such that the electrode member exits the electrode guide at the proximal opening and is guided into the patient’s skin at the predefined angle with respect to the contact surface.

21. The electrode mount of claim 20, wherein the, or each, electrode guide is substantially elongate.

22. The electrode mount of claim 20 or claim 21, wherein the, or each, electrode guide comprises a cylindrical-like passage within the body.

23. The electrode mount of any one of claims 20 to 22, wherein the electrode guide comprises a bend such that the predefined angle is substantially different to an angle at which the electrode member enters the electrode guide at the distal opening.

24. The electrode mount as claimed in any one of claims 18 to 23, wherein the contact surface is shaped in accordance with an expected contour of a patient’s skin.

25. The electrode mount as claimed in any one of claims 18 to 24, configured for use with one or more electrode members, the, or each, electrode member corresponding to a needle-based electrode as claimed in any one of claims 1 to 14.

26. The electrode mount as claimed in any one of claims 18 to 25, comprising an electrically conductive coupling between two or more inserted electrode members such that the two or more inserted electrode members correspond to a single electrode.

27. The electrode mount of any one of claims 18 to 26, comprising at least one lead connector configured for electrical coupling to a lead, wherein the at least one lead connector provides an electrically conductive pathway between an associated at least one inserted electrode member and the lead.

28. The electrode mount of claim 27, wherein the, or each, lead connector is permanently electrically coupled to a lead.

29. The electrode mount of claim 27, wherein the, or each, lead connector comprises a lead attachment mechanism enabling a lead to be removably attached and thereby put into electrical contact with its lead connector.

30. The electrode mount of any one of claims 18 to 29, each electrode guide associated with engagement means for securing an inserted electrode member with respect to the electrode guide.

31. The electrode mount of claim 30 when dependent on claim 29, wherein at least one engagement means is further adapted to form at least a portion of the electrically conductive pathway between an inserted electrode member and its associated lead.

32. The electrode mount of claim 30 or claim 31, wherein the at least one engagement means comprises a screw.

33. The electrode mount of any one of claims 30 to 32 when dependent on claim 29, wherein at least one engagement means and lead connector comprise the same structure.

34. The electrode mount of claim 33, wherein said same structure comprises an electrically conductive tab lockable at a position in contact with an inserted electrode member thereby inhibiting movement of the inserted electrode member and providing the electrically conductive pathway between the inserted electrode member and the lead.

35. The electrode mount of any one of claims 18 to 34, wherein the body comprises two or more spaced apart and aligned feet extending outwards from a common portion of the body.

36. An electrode mount system comprising one or more electrode mounts as claimed in any one of claims 18 to 35.

37. The electrode mount system of claim 36, further comprising one or more adhesive elements, wherein each adhesive element comprises a patient-side adhesive surface and a mountside adhesive surface, and wherein the, or each, electrode mount is affixed to the patient’s skin using an adhesive element.

38. The electrode mount system of claim 36 or claim 37, further comprising one or more electrode members, wherein each electrode member comprises a handle, and wherein the electrode guides are configured to block the handles from entering the electrode guides, such as to enable control of a maximum depth of insertion of the electrode members into the patient’s skin.

39. The electrode mount system of any one of claims 36 to 38 when dependent upon any one of claims 18 to 27, wherein the, or each, electrode member is electrically coupled to a lead independently of the one or more electrode mounts.

40. A method for inserting an electrode member into the skin of a patient using an electrode mount, comprising the steps of: affixing the electrode mount to a location on the patient’s skin, wherein the electrode mount comprises a body having a contact surface for positioning on a patient’s skin, wherein the body comprises one or more electrode guides for facilitating insertion of an electrode member into the patient’s skin at a predefined angle when the contact surface is positioned on the patient’s skin, and wherein the electrode mount is affixed to the patient’s skin at its contact surface; for the, or each, electrode guide: inserting an electrode member into a distal opening of the electrode guide, and passing the electrode member through the body of the electrode mount via the electrode guide in an insertion direction, such that an end of the electrode member exits the electrode mount at a proximal opening of the electrode guide and enters the patient’s skin41. A method for using an electrode mount, comprising the steps of: inserting an electrode member into a distal opening of the electrode guide, wherein the electrode mount is affixed to a location on the patient’s skin, wherein the electrode mountcomprises a body having a contact surface for positioning on a patient’s skin, wherein the body comprises one or more electrode guides for facilitating insertion of an electrode member into the patient’s skin at a predefined angle when the contact surface is positioned on the patient’s skin, and wherein the electrode mount is affixed to the patient’s skin at its contact surface, and passing the electrode member through the body of the electrode mount via the electrode guide in an insertion direction, such that an end of the electrode member exits the electrode mount at a proximal opening of the electrode guide and enters the patient’s skin; obtaining biological signal measurements of the patient using the one or more electrode members; and removing the one or more electrode members from the patient’s skin and the electrode mount by moving the one or more electrode members along the electrode guide in an opposite direction to the insertion direction.

42. The method of claim 40 or claim 41 applied to the electrode mount of any one of claims 18 to 35.

Images