GB2586331A

GB2586331A - Electrode and garment

Info

Publication number: GB2586331A
Application number: GB2008412.5A
Authority: GB
Inventors: Kunovski Philip
Original assignee: Kymira Ltd
Current assignee: Kymira Ltd
Priority date: 2019-06-20
Filing date: 2020-06-04
Publication date: 2021-02-17
Anticipated expiration: 2040-06-04
Also published as: GB2586331B; GB202008412D0; WO2020254833A1; GB201908818D0

Abstract

Garment 200, e.g. a top worn on a torso, comprises at least one electrode 100 located on an interior surface, for measuring ECG, EEG, EMG or other physiological signals. The electrode has a first portion 101 for electrical connection with the body, and second portion 102 configured to grip the skin and restrict movement during measurement, preventing the introduction of noise. The second portion may partially surround the first and may have a concave portion (106, fig. 2B) from which air can be forced out to give suction against the skin. Porosity may improve grip (by texture) and conduction (as sweat is drawn into pores). The electrode may comprise carbonised silicone and may be biocompatible. The garment may comprise an elastic material configured to apply compression to the skin when worn, and may also comprise conductive tracks or yarns connected to electrodes, disposed in a waterproof membrane.

Description

ELECTRODE AND GARMENT

FIELD OF THE INVENTION

The present invention relates to a garment comprising an electrode for measuring electrical signals produced by a human. Other aspects relate to an electrode for measuring electrical signals produced by a human, and a system and method for analysing electrical signals produced by a human

BACKGROUND

The human heart is effectively a two-stage electric pump. Its electrical activity can be monitored through electrodes placed on the skin of a person, known as electrocardiography. Electrocardiography is used to measure electrical signals produced by a heart, and can be used to measure the rate and rhythm of a heartbeat, indicating blood flow to the heart. A common form of capturing the electrical signals is in an electrocardiogram (ECG). There are numerous different ECG measurements that may provide different information about cardiac activity, and in differing levels of detail. For example, a 12-lead ECG measurement requires 10 electrodes and produces 12 electrical views of the heart. ECG measurements can also be made using fewer electrodes such as 2-Icad, 3-lead and 6-lead ECG measurements.

There is widespread agreement that sudden cardiac death (SCD) is the leading medical cause of death in athletes. A systematic review by Corrado and Zorzi (2018) observed sizeable proportions of athletes who died suddenly (ranging from 5% to 25% of the reported series) who had no evidence of structural heart diseases. Rather, the cause of those athletes' cardiac arrests was likely related to a primary electrical heart disease such as inherited cardiac ion channel defects (channelopathies), including long and short QT syndromes, Brugada syndrome and catecholaminergic polymorphic VT. ECG measurements offer the potential to detect (or to raise clinical suspicion of) such lethal conditions manifesting with ECG abnormalities.

Many heart rhythm irregularities do not show up at the time ECG measurements arc taken. Tins is typically because an individual is only subject to testing for a very brief amount of time. Abnormal heart rhythms and other types of cardiac symptoms can appear intermittently, so may not be captured during an ECG measurement only lasting for a short period of time.

Monitoring for a longer period of time is therefore necessary to detect and record such abnormal cardiac events.

However, electrodes typically used in ECG measurements require adhesive and/or conductive gel in contact with the skin. This can cause skin irritation and other adverse reactions, a risk which is only increased with increasing the length of time the electrodes are in contact with the skin. The accurate setup of the electrodes on the skin is also crucial to the quality of the measurements taken. Typically. ECG measurements are sensitive to motion artefacts and signal noise caused by movement of the person during measurement (which require the person to remain still and/or breathe shallowly)

SUMMARY

According to a first aspect, there is provided an electrode for measuring electrical signals produced by a person. The electrode may comprise a first portion configured to form an electrical connection directly with skin of the person to measure electrical signals. The electrode may comprise a second portion configured to grip to the skin to prevent movement of the electrode during measurement of electrical signals.

The electrode may provide reliable measurement of electrical signals produced by a person. The second portion enables the electrode to contact the skin and prevent movement of the electrode during measurement without requiring adhesive to affix the electrode to the skin.

The first portion enables the electrode to directly contact the skin to accurately and reliably measure electrical signals without requiring conductive gel in contact with the skin. Skin irritation and other adverse reactions may therefore be reduced or eliminated, without reducing measurement quality The electrode may be worn or used without needing to be in the presence of a healthcare professional and during normal movement/activity, including sport or exercise.

The first portion and the second portion may together form a surface configured to contact an area of skin of the person during measurement of electrical signals. To form the surface, the first portion and the second portion may be arranged laterally with respect to one another.

Arranging the first portion and the second portion to be located on or share one common surface may reduce a thickness of the electrode relative to a standard electrode for measuring electrical signals produced by a person. A reduced electrode thickness may reduce stiffness of the electrode, allowing the electrode to conform more easily to the skin. The first and second portion may be unitary and/or integrally formed together. The first and second portion may be positioned adjacent each other, and/or maybe connectable or connected or attachable or attached together.

The surface configured to contact an area of skin of the person during measurement of electrical signals may be or comprise an inner region comprising the first portion. Thc surface may also be or comprise an outer region comprising the second portion. The outer region may at least partially surround the inner region.

The inner region and the outer region may be or comprise substantially the same shape. Alternatively, the inner region and the outer region may be or comprise different shapes. A shape of each of the inner region and the outer region may be tailored to a specific location of the electrode on the skin. A shape of the inner region and the outer region tailored to a specific skin location may improve signal quality measured by the electrode. The signal quality may be improved by optimising or maximising conductive contact of the first portion with the skin, and optimising or maximising gripping contact of the second portion with the skin.

The inner region may be or comprise a substantially circular shape. The outer region may be or comprise one or more arcs substantially concentric with the inner region. Alternatively, the outer region may be or comprise a ring substantially concentric with the inner region. The outer region may ensure that force gripping the outer region to the skin is distributed evenly. An even distribution of force by the outer region may result in improved conductive contact between the inncr region and the skin.

The second portion may be shaped to create a suction effect to grip to the skin. The suction effect may further improve signal quality measured by the electrode by reducing movement of the electrode on the skin during measurement.

The second portion may be or comprise a textured surface to grip to the skin to prevent movement of the electrode during measurement. The first portion may also be or comprise a textured surface to grip to the skin to prevent movement of the electrode during measurement. The textured surface(s) may further improve signal quality measured by the electrode by reducing movement of the electrode on the skin during measurement.

At least a part of the first portion may be porous. The porosity of the first portion (or a part thereof) may improve conductive contact of the first portion with the skin. Pores of the first portion may provide a textured surface to grip to the skin to prevent movement of the electrode during measurement. Pores of the first portion may also wick sweat from the skin during measurement (e.g., via capillary action). Minerals in sweat from the skin may improve conductive contact of the first portion with the skin during measurement.

The first portion may be configured to deform or compress when pressure is applied to the electrode to bring the electrode into contact with the skin. Additionally or alternatively, the first portion may have a greater thickness than the second portion. The firs( portion may be configured to deform or compress to a thickness substantially equal to a thickness of the second portion. Deformation or compression of the first portion may provide improved conductive contact of the first portion with the skin. The first portion may accommodate or conform to topographical features of the skin.

At least one of the first portion and the second portion may be or comprise a biocompatible material (or a portion of biocompalible material). The first portion may be or comprise carbonised silicone. The second portion may be or comprise silicone. Biocompatible materials may further reduce or eliminate skin irritation which might otherwise result from bring an electrode into contact with the skin.

According to a second aspect, there is provided a garment comprising at least one electrode according to the first aspect. The at least one electrode may be part of the garment, or be located on an interior surface of the garment when the garment is worn by a person. By locating the at least one electrode on an interior surface of the garment, the electrode may easily be brought into contact with skin of the person.

The garment may be formed of or comprise an elastic material configured to apply compression to skin of a person such the at least one electrode grips to the skin when the garment is worn by the person. Compressive force applied by the garment may further reduce movement of the electrode on the skin during measurement. Compression fabrics comprising elastic material to apply compression to the skin are commonly used by sportspeople (amateur and professional). Incorporating electrical signal measurement capability into compression fabric may provide a simple way in which to monitor sportspeople during one or more of exercise, training Of competition.

The garment may comprise at least two electrodes, and optionally comprises three, four, five, six, seven, eight, nine, ten or more electrodes. The garment may comprise any number of electrodes in order to measure desired electrical signals produced by a person. The electrodes may be inlegrated into or be located on the interior surface of the garment such that a potential difference across an organ of the person is measurable in at least one direction when the garment is worn by the person. An organ of the person may be a heart, a brain, a muscle or another organ.

The electrodes may be integrated into or be located on the interior surface of the garment such that impedance of at least one volume of tissue of the person is measurable when the garment is worn by the person.

The garment may be configured to be worn on a torso of the person. The garment may be a top such as a t-shirt, shirt, juniper, sweatshirt or hooded sweatshirt. Alternatively, the garment may be configured to bc worn on lower limbs of the person. The garment may be a pair of shorts, trousers, tights or leggings. The garment could be a whole-body garment such as a onesie.

The at least one electrode may be located such that it is configured to obtain an EMG signal of one or more muscles of a person when the garment is worn by the person.

The at least one electrode may be located such that the electrode is configured to obtain an ECG signal of a person when the garment is worn by the person.

The at least one electrode may be located such that the electrode is configured to obtain an impedance measurement of tissue of a person when the garment is worn by the person. The at least one electrode may be located such that impedance measurements may be collected according to techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG) and electrical impedance tomography (EIT). The electrode being located so as to obtain an impedance measurement may enable the electrode to detect electrical signals indicating, for example, skin response (for example, to stress or exercise), ion content in perspiration, respiration, blood volume, blood flow, and hemodynamic parameters such as stroke volume, cardiac volume and cardiac output. The electrode may also contribute to obtaining an impedance measurement of tissue of a person by applying an electrical stimulus to the person (for example, the electrode may be driven using an electrical current). The electrode may simultaneously detect an electrical signal and apply an electrical stimulus.

The garment may be an item of headwear, such as a hat or cap. The at least one electrode may be configured to obtain an EEG signal of a person when the item of hcadwcar is worn by the person.

The garment may comprise an electrically conductive track electrically connected at a first end to the first portion of the at least one electrode. The conductive track may be configured to transmit electrical signals measured by the electrode to an external device for analysis or further transmission. The conductive track may have or comprise an elongated planar configuration. An elongated planar configuration may allow the conductive track to transmit electrical signals measured by the electrode without causing discomfort or irritation to a person wearing the garment (a standard cylindrical wire would protrude further from the interior surface of the garment).

The conductive track may comprise a conductive layer disposed between (for example, encapsulated by) two or more insulating layers. The insulating layers may be or comprise a waterproof material. Waterproof material may protect the conductive layer from damage (for example, damage caused by sweat or other liquids such as rain permeating through the garment) The conductive track may be disposed between the interior surface of the garment and the first portion of the electrode. The conductive track may be affixed to the interior surface of the garment. The conductive track may be affixed to the garment using an adhesive.

Alternatively, the conductive track may be stitched into the garment.

According to a third aspect, there is provided a garment comprising at least one electrode for measuring electrical signals produced by a person. The at least one electrode may be located on an interior surface of the garment when the garment is worn by a person The at least one electrode may comprise a first portion. The first portion may be configured to form an electrical connection directly with skin of the person to measure electrical signals without conductive gel. The at least one electrode may also comprise a second portion. The second portion may be configured to grip to the skin without adhesive to prevent movement of the electrode during measurement of electrical signals.

The garment of the third aspect may comprise any of the optional features, in any combination, of the electrode of the first aspect or the garment of the second aspect.

According to a fourth aspect, there is provided a method of manufacturing a garment comprising electrodes for measuring electrical signals produced by a person. The electrode may be or comprise the electrode of the first aspect. The method may comprise affixing a first portion of the electrode onto a surface of the garment. The first portion of the electrode may be configured to form an electrical connection directly with skin of the person to measure electrical signals. The method may further comprise affixing a second portion of the electrode onto a surface of the garment. The second portion of the electrode may be configured to grip to the skin to prevent movement of the electrode during measurement of electrical signals.

The method may comprise manufacturing one or both of the first portion of the electrode and the second portion of the electrode separately from the garment, prior to affixing the electrode portion(s) to the surface of the garment. The method may comprise manufacturing each of the first portion of the electrode and the second portion of the electrode separately from the garment and separately from one another. Alternatively, the method may comprise manufacturing both the first portion of the electrode and the second portion of the electrode together to form a complete electrode separately front the garment. The electrode portions may be manufactured substantially simultaneously or at different times. Manufacturing electrode portions or a complete electrode separately from the garment may increase manufacturing efficiency. A greater number of electrode portions or electrodes may be manufactured simultaneously, as individual electrode portions or electrodes may take up less space (for example, in a curing oven) than a garment.

The method may comprise manufacturing one or both of the first portion of the electrode and the second portion of the electrode on the surface of the garment. Affixing the electrode portion(s) to the surface of the garment may comprise manufacturing the electrode portion(s) on the surface of the garment. The electrode portions may be manufactured substantially simultaneously or at different times. Manufacturing electrode portions or electrodes on the surface of the garment may improve adhesion or bond strength between the electrode portions or electrodes and the garment. That may improve performance and durability of the garment.

The method may comprise partially or fully curing one or both of the first portion of the electrode and the second portion of the electrode on a surface separate from the garment, prior to affixing the electrode portion(s) to the surface of the garment. The electrode portion(s) may be located in a mould during curing.

Affixing the electrode portions to the surface of the garment may comprise adhering one or both of the first portion of the electrode and the second portion of the electrode to the surface of the garment. Affixing the electrode portion(s) to the surface of the garment may comprise adhering one or both of the electrode portions to the surface of the garment using an adhesive, for example a silicone based adhesive.

The method may comprise applying a primer to the surface of the garment prior to affixing the electrode portions to the surface of the garment. The primer may clean the surface of the garment and prepare the surface of the garment to bond with the electrode portions.

The method may comprise curing one or both of the first portion of the electrode and the second portion of the electrode on the surface of the garment. Affixing the electrode

S

portion(s) to the surface of the garment may comprise curing one or both of the first portion of the electrode and the second portion of the electrode to the surface of the garment. The electrode portion(s) may be located in a mould during curing.

According to a fifth aspect, a method of identifying features in an ECG signal is provided.

The method may comprise determining a position of one or more zero-crossing points in one or more nth order differentials of the ECG signal relative to a position of at least one known feature in the ECG signal. The method may also comprise identifying one or more features in the ECG signal by attributing each zero-crossing point in the one or more 11th order differentials of the ECG signal to a feature in the ECG signal based on the position of each zero-crossing point in the one or more nn differentials of the ECG signal relative to the position of the known feature in the ECG signal.

The method of the fifth aspect may be performed for either or both of diagnostic purposes and non-diagnostic purposes.

The at least one known feature in the ECG signal may be or comprise one or more known R-peaks in the ECG signal.

The method may further comprise determining positions of zero-crossing points of a second order differential of the ECG signal prior to a position of a known R-peak in the ECG signal. The method may also comprise identifying a start position of a QRS complex in the ECG signal by attributing the zero-crossing point of the second order differential of the ECG signal having the second-smallest difference in position relative to the position of the known R-peak in the ECG signal to a start position of a QRS complex in the ECG signal.

The method may further comprise determining positions of zero-crossing points of a zeroth order differential of the ECG signal after a position of a known R-peak in the ECG signal. The method may also comprise identifying an end position of a QRS complex in the ECG signal by attributing the zero-crossing point of the zeroth order differential of the ECG signal having the second smallest difference in position relative to the position of the known R-peak in the ECG signal to an end position of a QRS complex in the ECG signal.

The method may further comprise filtering the ECG signal prior to identifying features in the ECG signal. The method may comprise filtering the ECG signal to remove high-frequency noise from the ECG signal and/or to correct a wandering baseline of the ECG signal.

The method may further comprise identifying features in both the ECG signal and the filtered ECG signal.

The method may further comprise determining a position of one or more further zero-crossing points in one or more nth order differentials of the ECG signal relative to a position of one or more previously determined zero-crossing points in one or more nth order differentials of the ECG signal. The method may also comprise identifying features in the ECG signal by attributing each further zero-crossing point in the one or more nth order differentials of the ECG signal to a feature in the ECG signal based on the position of the one or more further zero-crossing points in the one or more nth order differentials of the ECG signal relative to the position of the one or more previously determined zero-crossing points in the one or more nth order differentials of the ECG signal.

The one or more nth order differentials of the ECG signal may be or comprise at least one of a zeroth order differential of the ECG signal, a first order differential of the ECG signal, a second order differential of the ECG signal, and a higher order differential of the ECG signal.

According to a sixth aspect, there is provided a system. The system may comprise one or more electrodes for measuring electrical signals produced by a person. The system may also comprise a processor. The processor may be configured to receive an ECG signal from the one or more electrodes. The processor may be configured to determine a position of one or more zero-crossing points in one or more nth order differentials of the ECG signal relative to a position of at least one known feature in the ECG signal. The processor may also be configured to identify one or more features in the ECG signal by attributing each zero-crossing point in the one or more nth order differentials of the ECG signal to a feature in the ECG signal based on the position of each zero-crossing point in the one or more nth differentials of the ECG signal relative to the position of the known feature in the ECG signal.

Each electrode may be or comprise an electrode according to the first aspect.

The processor may be further configured to perform any method steps according to the fifth aspect.

The system may further comprise a display configured to display the ECG signal.

The processor may be configured to produce an annotated ECG signal by annotating the ECG signal at positions in the ECG signal corresponding to identified features in the ECG signal.

The display is configured to display the annotated ECG signal.

According to a seventh aspect, a method of identifying an ectopic heartbeat in an ECG signal is provided. The method may comprise identifying a position of each feature in at least one pair of successive corresponding features in the ECG signal. The method may additionally comprise determining a distance between the positions of each feature in each pair of successive corresponding features in the ECG signal. The method may also comprise determining that an ectopic heartbeat is present in the ECG signal if the distance between the positions of each feature in a pair of successive corresponding features in the ECG signal is less than a threshold distance.

The method of the seventh aspect may be performed for either or both of diagnostic purposes and non-diagnostic purposes.

The method may further comprise identifying a position of each feature in at least two pairs of successive corresponding features in the ECG signal. The method may also comprise determining an average distance between the positions of each feature in each pair of successive corresponding features in the ECG signal. The method may comprise determining that an ectopic beat is present in the ECG signal if the distance between each feature in a pair of successive corresponding features in the ECG signal is less than the average distance multiplied by a scaling factor.

The scaling factor may be between substantially 0.4 and 0 8, and may be substantially 0.6.

The method may further comprise identifying a position of each feature in two successive pairs of successive corresponding features in the ECG signal, wherein the two successive pairs of successive corresponding features share a common feature. The method may also comprise determining a distance between each feature in each pair of successive corresponding features in the ECG signal. The method may additionally comprise determining that an ectopic beat is present in the ECG signal if the distance between each feature in the earlier pair of successive corresponding features in the ECG signal divided by the distance between each feature in the later pair of successive corresponding features in the ECG is less than the threshold.

The threshold may be between substantially 0.4 and 0.8, and may be substantially 0.6.

The feature may be or comprise any suitable feature in the ECG signal. The feature may be or comprise one of an R-peak, a P wave or a T wave.

The processor of the systcm of the sixth aspect may be configured to perform any method steps according to the seventh aspect.

The optional features from any aspect may be combined with the features of any other aspect, in any combination. For example, the method of the fifth or seventh aspects may comprise using a device that includes any of the features described with reference to any one or more of the electrode, garment or system of the first, second, third or sixth aspects. Furthermore, the system of the sixth aspect may be configured to perform the method of the fifth or seventh aspects (including any optional features thereon.

Features which are described in the context of separate aspects and embodiments of the invention may be used together and/or be interchangeable wherever possible. Similarly, where features are, for brevity, described in the context of a single embodiment, those features may also be provided separately or in any suitable sub-combination. Features described in connection with the method may have corresponding features definable with respect to the device and use of the device, and these embodiments are specifically envisaged.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described by way of example with reference to the accompanying drawings in which: FIGs. IA and 1B show plan views of electrodes comprising a conductive portion and a non-conductive portion in accordance with an embodiment of the invention; FIGs. 2A, 2B and 2C show side views of electrodes shaped to provide a suction effect in accordance with an embodiment of the invention; FIGs. 3A and 3B show plan views of electrodes comprising male and female engagement features between a conductive portion and a non-conductive portion in accordance with an embodiment of the invention, FIG. 4 shows a garment comprising an electrode comprising a conductive portion and a non-conductive portion in accordance with an embodiment of the invention; FIGs. 5A and 5B show side views of electrodes affixed to a garment in accordance with an embodiment of the invention; FIGs, GA, GB and 7 show moulds or stencils used to manufacture electrodes comprising a conductive portion and a non-conductive portion in accordance with an embodiment of the invention; FIG. 8 shows a plan view of electrodes affixed to a garment in accordance with an embodiment of the invention; FIG. 9 shows a side view of one of the electrodes of FIG. 8; FIGs, 19A, 10B, 10C and 10D show views of an electrode connected to a conductive track and affixed to a garment, and a view of a conductive track, in accordance with an embodiment of the invention; FIGs. 11A and 11B show plan views of conductive tracks comprising apertures or curved portions in accordance with an embodiment of the invention; FIGs. 12A. 12B. 12C, 12D. 12E and 12F show various embodiments of a conductive track or a conductive yarn connected to an acquisition electronics unit; FIG. 13 shows a number of nth order differentials of a signal relative to one another; FIG. 14 shows a method of analysing an ECG signal in accordance with an embodiment of the invention; and FIG. 15 shows a system for measuring and identifying features in an ECG signal in accordance with an embodiment of the invention.

Like reference nmnbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

Electrode and Garment Construction Figure IA shows an embodiment of an electrode 100 for measuring electrical signals produced by a person. The electrical signals produced by a person may be one or more of electrical signals front the heart (electrocardiography), electrical signals from the brain (electroencephalography), electrical signals from a muscle or muscle group (electromyography) or other electrical signals produced by a person. The electrical signals may additionally or alternatively be or comprise a bioimpedance of one or more tissues of the person. The electrode 100 may additionally or alternatively be used to apply an electrical stimulus, for example to obtain bioimpedance measurements (such as by driving an electrical current through the electrode 100). The electrode 100 comprises a first portion 101 configured to form an electrical connection directly with the skin. The electrode 100 comprises a second portion 102 configured to grip to the skin to prevent movement of the electrode 100 during measurement or application of electrical signals. Movement of an electrode during measurement can introduce noise into a signal measured by the electrode, which may have an adverse impact on the reliability of any results derived from a signal measured by the electrode. In the embodiment shown, the first portion 101 is connected or attached (or connectable or attachable) to the second portion 102. In alternative embodiments, the first portion 101 and the second portion 102 may not be connected or attached (or connectable or attachable), or may be connected or attached (or be connectable or attachable) indirectly. In the embodiment shown, the second portion 102 surrounds a perimeter of the first portion 101.

Alternatively, the second portion 102 may only partially surround a perimeter of the first portion 101. Additionally or further alternatively, the second portion 102 may be connected to the first portion 101 along one or more edges and/or surfaces of the first portion 101 and the second portion 102. The edges and/or surfaces of each of the first portion 101 and/or the second portion 102 may be straight or curved.

In the embodiment shown in Figure 1A, the first portion 101 and the second portion 102 each form a part of a surface 103. The surface 103 is configured to contact an area of skin of the person directly during measuring of electrical signals. The area of skin may be located on any part of the body of the person, for example on the head, neck, torso (e.g. chest, abdomen, upper back, lower back), limbs (e.g., arms, legs) or extremities (e.g., hands, feet, fingers, toes). In the embodiment shown, the first portion 101 forms an electrically conductive inner region 104 of the surface 103 configured to form an electrical connection with the skin when the surface 103 is in contact with the area of skin. The second portion 102 forms an outer region 105 of the surface 103 surrounding the inner region 103. The outer region 105 is configured to grip to the skin when the surface 103 is in contact with the area of skin to prevent movement of the sensor during measurement of electrical signals. In an embodiment, the surface 103 is substantially smooth and/or planar and/or the portions 101 and 102 substantially flush with respect to each other.

The size of the electrode 100 may vary depending on which part of the body of the person the area of skin is located. For example, an electrode 100 configured for use on the torso or limbs may be smaller than an electrode 100 configured for use on the head, neck or extremities.

Additionally he relative sizes or proportions of the first portion 101 and the second portion 102 may be varied and optimised to provide optimal performance of the electrode 100, accounting for both signal strength (e.g., maximise size of the first portion 101 to maximise signal strength measured by the electrode 100) and signal quality (e.g., maximise size of the second portion 102 to maximise signal quality measured by the electrode 100 by preventing movement of the electrode 100 during measurement). The optimal sizes and proportions of the first portion 101 and the second portion 102 may vary depending on which part of the body the area of skin with which the electrode 100 is in contact is located. For example, a flatter area of skin may utilise an electrode 100 having a larger footprint or surface area. In some embodiments, such an electrode 100 may require a relatively smaller second portion 102 in order to grip to the skin sufficiently to prevent movement of the electrode 100 during measurement when compared to a less flat area of skin. Conversely, a less flat area of skin may utilise an electrode 100 having a smaller footprint or surface area. In some embodiments, such an electrode 100 may require a relatively larger second portion 102 in order to grip to the skin sufficiently to prevent movement of the electrode 100 during measurement. In some embodiments, the electrode 100 has a diameter of between 1 cm and 5 cm, or between substantially 1 cm and 4 cm, or between substantially 1 cm and 3 cm. In some embodiments, the electrode 100 has a thickness of between substantially 0.5 mm and 5 mm, or between substantially 0.5 mm and 4 mm, or between substantially 0.5 mm and 3 min. or between substantially 0.5 mm and 2 mm. In some embodiments, a radial width of the first portion 101 of the electrode 100 is equal to a radial width of the second portion 102 of the electrode 100. Alternatively, a radial width of the first portion 101 of the electrode 100 may be greater than or less than a radial width of the second portion 102 of the electrode 100.

In the embodiment shown in Figure 1A, the outer region 105 fully surrounds (e.g., encloses or covers an entire perimeter of) the inner region 104. Figure 1B shows an embodiment in which the outer region 105 comprises one or more portions 105a which surround only a part or parts of the inner region 104, leaving the remainder of the inner region 104 exposed. In the embodiments shown in Figure IA and Figure 1B, the inner region 104 is or comprises a circular shape. The outer region 105 is or comprises either a ring shape concentric with the inner region 104 (Figure 1A), or comprises one or more arc shapes 105a concentric with the inner region 104 (Figure 1B). Alternatively, each of the inner region 104 and the outer region 105 may be or comprise any shape (e.g., square, rectangular, polygonal shape, regular or irregular shape, curved shapes). The inner region 104 and the outer region 105 may be or comprise substantially the same shape, or may be or comprise different shapes. In an embodiment, the two major (e.g. upper and lower) surfaces of the electrode 100 are substantially the same.

Figure 2A shows a cross-sectional view of the embodiment of the electrode 100 shown in Figure lA and Figure 1B. In the embodiment shown, the second portion 102 of the electrode 100 is shaped or configured to create a suction effect to grip to the skin to prevent movement of the electrode 100 during measurement of electrical signals, in the embodiment shown, the second portion 102 comprises a concave portion 106 configured to form a fluid-tight seal when the second portion 102 is brought into contact with the skin. For example, the concave portion 106 may be located in the outer region 105, or in one or more of the portions 105a of the outer region 105. The concave portion 106 may be or comprise an arc extending across the second portion 102 and having a concave cross-sectional shape. The concave portion 106 may be or comprise one or more channels or grooves in the outer region 105. Ti/they may extend partially or fully around the extent of the outer region 105. in the embodiment shown, the concave portion 106 extends only across a part of a radial width of the second portion 102. Alternatively, the concave portion 106 may extend across a full radial width of the second portion 102, as depicted in Figure 2B. Pressure may be applied to the second portion 102 when bringing the electrode 100 into contact with the skin. The application of pressure to the second portion 102 forces air out of the concave portion 106, reducing the air pressure in the concave portion 106. The seal between the second portion 102 and the skin is then reformed. When the application of pressure is removed, as long as the seal between the second portion 102 and the skin remains intact, atmospheric pressure is greater than the air pressure in the concave portion 106 and forces the second portion 102 against the skin. The second portion 102 is therefore configured to grip or adhere to the skin to prevent movement of the electrode 100 during measurement. The suction effect provided by the second portion 102 may be sufficient to grip or adhere to the skin without any additional forces being applied.

Alternatively, or additionally, the second portion 102 may grip to the skin via other means.

For example, the second portion 102 may comprise a textured surface (for example, an undulating surface) configured to grip to the skin. The texture may be provided on, or as part of, at least a part of the second portion 102. The second portion 102 may also or alternatively be or comprise a material which provides frictional adhesion to the skin that prevents or limits movement of the electrode 100 during measurement. For example, the second portion 102 may be or comprise a 'tacky' material, e.g., a polymeric or elastomeric material such as silicone or rubbcr. The second portion 102 being configured to grip to the skin to prevent movement of the electrode 100 during measurement of electrical signals may enable the electrode 100 to be used without requiring an adhesive to affix the electrode 100 to the skin, as is usually required in, for example. ECG measurements.

in an embodiment, the first portion 101 comprises an electrically conductive composite material Of mixture of materials. For example, the first portion 101 may be Of Comprise carbonised silicone (e.g., a mixture of silicone and carbon black). Other electrically conductive composite materials or mixtures of materials may be uscd, for example polymeric materials comprising or doped with conductive material (such as silver or gold). Alternatively, a single component electrically conductive material may be used, for example a conductive polymeric or elastomeric material.

The first portion 101 may be or comprise a porous material. For example, carbonised silicone comprises a porous structure. Alternatively, conductive materials of the first portion 101 which are not porous may selectively be made porous, for example by etching or by foaming techniques. The first portion 101 being porous may provide a textured surface for the first portion 101. The textured surface of the first portion 101 may aid frictional adhesion of the first portion 101 to the skin to minimise movement of the electrode 100 during measurement of electrical signals. Porosity of the first portion 101 may also improve conduction of the first portion 101, as minerals from sweat on the skin may be taken into pores of the first portion 101 In some embodiments, the first portion 101 comprises a material which is easily deformable and/or compressible, allowing the first portion 101 to conform to the shape of an area of skin. In some embodiments, the first portion 101 has a greater thickness than the second portion 102, as shown in Figure 2C. In order to bring the second portion 102 into contact with the skin, the first portion 101 is deformed and/or compressed. The deformation and/or compression of the first portion 101 may improve conductive contact of the first portion 101 with the skin, for example by the first portion 101 deforming or compressing to accommodate or conform to topographical features in the skin.

In the embodiment shown, the second portion 102 comprises a non-conductive material. For example, the second portion 102 may be or comprise an elastomeric material such as silicone elastomer. One or both of the first portion 101 and the second portion 102 may be or comprise biocompatible material.

In some embodiments, the first portion 101 and the second portion 102 additionally or alternatively each comprise corresponding male and female engagement features 10'7 (e.g., a tab or flange, and a groove or recess), as shown in Figures 3A and 3B respectively. One or more male/female mating pairs may be provided. Figure 3A depicts male engagement features 107 extending from the first portion 101 into the second portion 102, whilst Figure 3B depicts male engagement features 107 extending front the second portion 102 into the first portion 101. The engagement features 107 may help to improve bonding and adhesion between the first portion 101 and the second portion 102. Although the mating features in Figure 3A and 3B are substantially rectangular in shape, it will be appreciated that they may be of any shape that provides for the male engagement feature to be receivable within thc female engagement feature.

Figure 4 shows an embodiment of a garment 200 comprising an electrode 100. The garment is configured to be worn by a user whilst measuring electrical signals produced by the user using the electrode 100. The dashed line of the electrode 100 indicates a position of the electrode 100, which is located on an internal surface of the garment 200 (in order to contact an area of skin of the user). In the embodiment shown, the garment 200 is a top configured to be worn on a torso of a user. Alternatively, the garment 200 may be any wearable garment, for example, a hat, shorts, trousers etc. In the embodiment shown, the garment 200 comprises one electrode 100. Alternatively, the garment 200 may comprise a plurality of electrodes 100, for example two, three, four, five, six, seven, eight, nine or more electrodes 100. In some embodiments, the garment 200 comprises ten electrodes 100. The ten electrodes 100 may be located on the garment 200 such that a 12-lead ECG measurement may be performed using the ten electrodes 100. The electrode 100 is affixed to the garment 200.

In an embodiment, fabric of the garment 200 comprises an elastic material configured to apply a compressive force to skin of the user e.g., compression fabric. Compression fabric may comprise fabric material blended with clastanc, for example Lycra® or Spandex®.

Alternatively, compression fabric may be manufactured from other material blends such as blends comprising rubber and/or neoprene rubber. Compression fabric blends comprising rubber and/or neoprene rubber are typically used in water-based sports such as swimming. Compressive force provided by compression fabric, may force the electrode 100 against an area of skin of the user. In conjunction with the second portion 102 of the electrode, the compressive force provided by compression fabric may help to prevent movement of the electrode 100 during measurement of electrical signals without requiring adhesive. Alternatively, the garment 200 may comprise non-stretch fabric (i.e., fabric that is not compression fabric). The garment 200 may be configured to closely match or fit a form (e.g., body shape or body part shape) of the user. The close match or fit of the garment 200 may also provide a compressive force to force the electrode 100 against an area of skin of the user. Alternatively, the garment 200 may not be configured to closely match or fit a form of the user, and may fit loosely.

In some embodiments, the electrode 100 is or comprises materials which require curing prior to use (for example, some polymeric or elastomeric materials such as silicone, or compounds and mixtures comprising silicone). The second portion 102 of the electrode 100 (and optionally the first portion 101 of the electrode 100) may comprise one or more materials which require curing prior to use. The electrode 100 is affixed to the fabric of the garment 200 by curing the electrode 100 directly onto the fabric of the garment 200. Curing one or both of the first portion 101 and the second portion 102 of the electrode 100 directly onto the fabric simultaneously bonds the electrode 100 to fabric of the garment 200. The material of the first portion 101 and/or the second portion 102 may be uncured or only partially cured prior to being applied to the fabric of the garment 200 and subsequently cured onto the fabric of the garment 200. Whilst the uncured or partially cured material of the electrode 100 is heated during the curing process, a decrease in viscosity associated with increased temperature allows the uncured material of the electrode 100 to wick into and spread through the fabric of the garment 200. This is illustrated in Figure 5A depicting material of the second portion 102 of the electrode wicking into the fabric 201 of the garment 200. The electrode 100 is therefore bonded not only to a surface of the garment 200, but bonded within the fabric of the garment 200. This may help to improve adhesion of the electrode 100 to the garment 200, making the electrode 100 more robust when incorporated into the garment 200. Additionally, no adhesive material such as a fabric glue is required to affix the electrode 100 to the garment 200, simplifying the overall manufacturing process.

In some embodiments, the first portion 101 of the electrode 100 is porous. During curing, the uncured or partially cured material of the second portion 102 may also wick into the porous structure (e.g., pores 1010 of the first portion 101, as illustrated in Figure 5B. It will be appreciated that the pores 101a shown in Figure 5B are exemplary in nature, and that the porous structure of the first portion 101 may comprise pores 101a of different shapes and sizes. This may help to anchor or affix the second portion 102 more securely to both the first portion 101 and the fabric 201.

The electrode 100 may be prepared and applied to the fabric 201 of the garment 200 in a variety of ways. In one embodiment, an uncured material for the first portion 101 is prepared. In this exemplary embodiment, a mixture of silicone and carbon black is prepared for the first portion 101, although it will be appreciated a similar process could be employed for a variety of curable materials used for the first portion 101 of the electrode 100. The uncured material for the first portion 101 is then applied to the fabric 201 of the garment 200. The uncured material is applied to the fabric 201 in a desired shape and size, and to a desired thickness, for example, depending on a site or shape of an area of skin with which the electrode 100 is intended to contact. The uncured material for the first portion 101 is applied by printing the uncured material onto the fabric 201 using a mould or stencil 300. The mould or stencil 300 (for example, as shown in Figure GA) is used to retain the first portion 101 in the correct shape or configuration during curing (e.g., within an aperture 301 defined in the stencil 300), ensuring accuracy of the dimensions of the first portion 101. In some embodiments, the uncured material for the first portion 101 is forced into the aperture 301 of the stencil 300 and onto the fabric 201 by applying the uncured material to the stencil 300 and moving a flat blade (not shown, but for example comprising an clastomeric material such as rubber) across a surface of the stencil 300. The stencil 300 is also used to locate the first portion 101 of the electrode 100 in the correct spatial position on the fabric 201 of the garment 200. In some embodiments, pressure is applied to the stencil 300 to prevent movement of the stencil 300 relative to the movement of the fabric 201 during curing (and therefore prevent bleeding or leakage of the uncured material across the fabric 201 during curing). Pressure may be applied, for example, by a press, or by one or more clips or clamps. A press may also be used to apply heat to the uncured material in order to cure the first portion 101. In some embodiments, the mould or stencil 300 is used to define the engagement features 107 of the first portion 101, as shown by a plurality of recesses 307 in the aperture 301 of the stencil 300 of Figure 6B. In some embodiments. the stencil 300 is or comprises a low-friction material or coating (for example, PTFE) to allow for easy release between the stencil 300 and the first portion 101 after curing.

Alternatively, the uncured material for the first portion 101 may be applied using a hand or machine operated dispenser, for example a nozzle in fluid communication with a reservoir containing the uncured material for the first portion 101. Alternatively, the uncured material for the first portion 101 may be applied by painting the uncured material onto the fabric 201, or by spraying the uncured material onto the fabric 201.

After the uncured material for the first portion 101 has been applied to the fabric 201. the uncured material is partially or fully cured before applying the second portion 102 to the fabric 201 in some embodiments, the uncured material for the first portion 101 is partially cured before applying the second portion 102. The uncured material is cured for between substantially 5 and 30 minutes at a temperature of between substantially 50 and 120°C. and may be cured for substantially 15 minutes at a temperature of substantially 80°C. By only partially curing thc first portion 101 before applying the second portion 102 to the fabric 201, adhesion between the first portion 101 and the second portion 102 of the electrode 100 during full curing may be improved. Alternatively, the first portion 101 may be fully cured before applying the second portion 102 to the fabric 201. The first portion 101 may be cured for a total time of between substantially, 15 and 60 minutes at a temperature of between substantially 50 and 120°C, and may be cured for a total time of substantially 30 minutes at a temperature of substantially 80°C. In some embodiments, the first portion 101 is cured in an oven. Alternatively, the first portion 101 may be cured using contact heating (e.g., via a heated press).

In other embodiments, the uncured material for the first portion 101 is partially cured in a desired shape or configuration, size and thickness on a surface separate from the fabric 201 of Eke garment. The uncured material is partially cured to an extent that the first portion 101 is able to retain its shape and does not exhibit liquid flow. The uncured material may be printed onto a surface using a mould or stencil 300, as outlined above, or otherwise applied to a surface. The surface may be or comprise a low-friction material or coating (for example, PTFE) to allow for easy release of the first portion 101 after partial curing. Once partially cured, the first portion 101 is removed from the surface. In some embodiments, the first portion 101 is then applied directly to the fabric 201 and fully cured onto the fabric 201.

Alternatively, the first portion 101 may be stored for future application onto the fabric 201, rather than immediate application. During application onto the fabric 201, the first portion 101 is located in a desired location on the fabric 201 of the garment 200. Once located on the fabric 201 of the garment 200, the first portion 101 is fully cured to adhere or bond the first portion 101 to the garment 200. The times and temperatures used for partially curing the first portion 101 prior to applying the first portion 101 to the fabric 201 may be substantially similar to those outlined above. Alternatively, the first portion 101 may be fully cured before being applied to the fabric 201. The first portion 101 may be affixed to the fabric 201 in an alternative manner, for example using an adhesive, or may be stitched into the fabric 201.

In sonic embodiments, after the first portion 101 is applied to the fabric 201 and either fully or partially cured, the second portion 102 is applied to the fabric 201. In one embodiment, an uncured material for the second portion 102 is prepared. In this exemplary embodiment, silicone is prepared for the second portion 102, although it will be appreciated that a similar process could be employed for a variety of curable materials used for the second portion 102 of the electrode 100. In some embodiments, a thinner is included in the uncured material mixture. Thinner may be used to control the amount of wicking of uncured material into the fabric 201. A greater proportion of thinner in the uncured material mixture may promote increased wicking of the uncured material into the fabric 201. The uncured material for the second portion 102 is applied to the fabric 201 of the garment 200. The second portion 102 is applied using a mould or stencil 400 similar to the mould or stencil 300 used in respect of the first portion 101, as shown hi. Figure 7. In some embodiments, an aperture 401 of the stencil 400 is larger than the aperture 301 of the stencil 300. The stencil 400 is placed on the fabric such that the partially or fully cured first portion 101 is located within the aperture 401. This allows the uncured material for the second portion 102 to fill one or more spaces surrounding the partially or fully cured first portion 101. The uncured material for the second portion 102 is then cured. The second portion 102 may be cured for a total time of between substantially 5 and substantially 60 minutes at a temperature of between substantially 50°C and substantially 120°C, and may be cured for a total time of substantially 15 minutes at a temperature of substantially 80°C.

Alternatively, the second portion 102 may be partially cured in a desired shape or configuration, size and thickness on a surface separate from the fabric 201 of the garment.

The uncured material is partially cured to an extent that the second portion 102 is able to retain its shape and does not exhibit liquid flow. The uncured material may be printed onto a surface using a mould or stencil 300, 400, as outlined above, or otherwise applied to a surface. The surface may be or comprise a low-friction material or coating (for example, PTFE) to allow for easy release of the second portion 102 after partial curing. Once partially cured, the second portion 102 is removed from the surface. In some embodiments, the second portion 102 is then applied directly to the fabric 201 and fully cured onto the fabric 201 around the partially or fully cured first portion 101. Alternatively, the second portion 102 may be stored for future application onto the fabric 201, rather than immediate application. During application onto the fabric 201, the second portion 102 is located relative to the first portion 101 already disposed on the garment 200. Once located on the fabric 201 of the garment 200, the second portion 102 is fully cured to adhere or bond the second portion 102 to the garment 200. If the first portion 101 is only partially cured prior to applying the second portion 102 to the fabric 201, the first portion 101 may be fully cured during curing of the second portion 102. The times and temperatures used for partially curing the second portion 102 prior to applying the second portion 102 to the fabric 201 may be substantially similar to those outlined above.

Alternatively, the electrode 100 may be produced or constructed, as a whole, separately from the garment 200. The electrode 100 may then be affixed, as a whole, to the fabric 201 of the garment 200, for example using an adhesive such as a silicone-based adhesive.

To manufacture the electrode 100 separately from the garment 200, uncured material for both the first portion 101 and the second portion 102 is applied to (for example, printed onto) a surface. The uncured material for both the first portion 101 and the second portion 102 is disposed within a mould located on the surface. The mould is configured to hold the first portion 101 and the second portion 102 in a desired shape and/or position relative to one another during curing, for example in a desired shape or configuration of the electrode 100. That may enable the first portion 101 and the second portion to bond to one another during the curing process to form a complete electrode 100, without requiring the first portion 101 and the second portion 102 to be adhered to one another separately. The surface may be a low-friction surface (for example, PTFE) to enable the electrode 100 to easily be separated from the surface after curing. The uncured material of the first portion 101 and the second portion 102 is then cured on the surface in order to form a complete electrode 100. The first portion 101 and the second portion 102 may bc cured at ambient or room temperature, for example up to substantially 24 hours (depending on temperature and humidity). Alternatively, the first portion 101 and the second portion may be cured at an elevated temperature, for example in an oven. For example, the first portion 101 and the second portion 102 may be cured for a total time of between substantially 2 hours to substantially 24 hours at a temperature of between substantially 40°C and 100°C, and may be cured for a total time of substantially four hours and substantially 20 hours at a temperature of between substantially 50°C and 80°C substantially 80°C. Alternatively, the first portion 101 and the second portion 102 may be cured using contact heating (e.g., via a heated press).

In the example described above, the uncured material of both the first portion 101 and the second portion 102 are applied to the surface substantially simultaneously. Alternatively, the uncured material of the first portion 101 may be applied to the surface and partially cured (for example, at ambient temperature or at an elevated temperature) prior to the uncured material of the second portion 102 being applied to the surface (or vice versa). The first portion 101 may be partially cured to an extent that the first portion 101 is able to retain its shape and does not exhibit liquid flow. That may enable the uncured material of the second portion 102 to bond to the first portion 101 whilst retaining the desired shape and/or configuration of both the first portion 101 and the second portion 102 of the electrode 100.

Once the first portion 101 and the second portion 102 have been cured, the completed electrode 100 is affixed to the fabric 201 of the garment 200, for example as described below.

A primer (for example, white spirit, naptha, xylene and/or heptanes) is applied to an area of the garment 200 to which the electrode 100 is to be affixed, prior to affixing the electrode 100 to the garment 200. The purpose of the primer may be to clean the area of the garment 200 to which it is applied (for example, to remove grease and/or dust), and to prepare the area of the garment 200 to which it is applied for adhesion to the electrode 100. The primer is left to dry, at least partially, before adhesive can be applied over the primer. The primer may be left to dry in a ventilated area for substantially 30 minutes. Alternatively, a primer may not be applied to the garment 200 prior to affixing the electrode 100 to the garment.

An adhesive is then applied between the garment 200 and the electrode 100 to affix the electrode 100 to the garment 200. The adhesive may be applied directly to either the garment (e.g., over the primer) or to the electrode 100 itself. The adhesive may be a silicone-based adhesive. For an electrode 100 comprising or manufactured from a silicone-based material, a silicone-based adhesive may provide maximal adhesion between the fabric 201 of the garment 200 and the electrode 100.The adhesive is then left to dry or cure. For example, the adhesive may be left to cure for between substantially 24 hours and substantially 7 days before the garment 200 may be used, depending on conditions such as temperature and humidity of the curing environment.

Optionally, after applying adhesive between the garment 200 and the electrode 100 to affix the electrode 100 to the garment 200, edges or surfaces of the electrode 100 which may have inadvertently developed defects (such as notches, recesses) during manufacturing may be finished. The defects may be finished by applying further uncured material of either the first portion 101 and/or the second portion 102 to the defects, as required. Additionally or alternatively, a sealant may be applied around an edge of the electrode 100 where the electrode 100 joins the garment 200. That may further secure the electrode 100 to the garment 200, and protect the electrode 100 from damage such as fluid infiltration once affixed to the garment 200. The additional uncured material and/or sealant may cure whilst the adhesive between the electrode 100 and the garment 200 is drying.

Manufacturing the complete electrode 100 as a complete unit prior to affixing the electrode to the garment 200 may enable increased manufacturing efficiency, as the first portion 101 and the second portion 102 can be cured separately from the garment 200. That may enable a greater number of electrodes 100 to be manufactured simultaneously, as individual electrodes 100 may take up less space (for example, in a curing oven) than a garment 200 on which uncured or partially cured first 101 and/or second 102 portions are disposed.

Alternatively, the first portion 101 and/or the second portion 102 may be cut to a desired shape or configuration from sheets of (for example, pre-cured) conductive and non-conductive material respectively. The shapes of the first portion 101 and the second portion 102 cut from the sheets may then be adhered to one another (for example, using an adhesive) prior to being affixed to the fabric 201 (for example, using an adhesive, or being stitched onto the fabric 201) to form an electrode 100. Alternatively, the first portion 101 and the second portion 102 may be arranged on and affixed to the fabric 201 to form an electrode 100 without first being adhered or attached to one another.

Embodiments of electrodes 100 affixed to fabric 201 of a garment 200 in accordance with the invention are shown in Figures 8A, 8B and 8C. Each of the electrodes comprises a first portion 101 comprising a mixture of silicone and carbon black, and a second portion 102 comprising silicone. The first portion 101 and the second portion 102 form a surface configured to contact skin of a person. The first portion 101 forms an electrically conductive inner region 104 configured to form an electrical connection with the skin, and the second portion 102 forms an outer region configured to grip to the skin. The electrode 100 in Figure SA comprises male engagement features 107 extending from the first portion 101 into the second portion 102. The first portion 101 of the electrode 100 in Figure 8C comprises an angled surface 101b at its circumference that is overlain by the second portion 102. This is illustrated in Figure 9. The surface 101b can instead be angled in the opposite direction, as illustrated by the dotted lines in Figure 9. The angle may be any angle substantially in the range -45 to 45 degrees (with the vertical being 90°, i.e. the range shown between the solid and dotted angled lines 101b). In another embodiment (not shown) the surface could be curved, or be or comprise a combination of linear and curved surfaces.

Figure 10A shows another embodiment of an electrode 100 affixed to fabric 201 of a garment in accordance with the invention. The electrode 100 is substantially as described above. In the embodiment shown, the electrode 100 is not provided (e.g. applied) directly on/to the fabric 201, but rather the electrode 100 is provided on/applied on or over a conductive track 108.

The conductive track 108 comprises a layer of conductive material 108a (for example, a conductive ink such as silver ink or copper ink). In the embodiment shown, the layer of conductive material 108a is applied directly to the fabric 201. Alternatively, the conductive track 108 may comprise a layer of conductive material 108a located between two or more layers of insulating material 108b (e.g., encapsulating the conductive layer 108a), as shown in Figure 10B. The two or more layers of insulating material 108b may be or comprise flexible polymeric or rubber materials, for example vinyl or polyurethane. The two or more layers of insulating material 108b may be or comprise insulating inks. The insulating layers 108b may be or comprise a waterproof material. In embodiments in which the layer of conductive material 108a is disposed between layers of insulating material 108b, a first end portion 109a of the layer 108a is covered by a layer 108b on a surface nearest the fabric 201, but is left exposed (i.e., not covered) on a surface furthest from the fabric 201. The dashed line in Figure 10B indicates where the first end portion 109a begins, or where the insulating layer 108b furthest from the fabric 201 stops. This allows the layer of conductive material 108a to form an electrical connection with the first portion 101 of the electrode 100 (when the electrode 100 is applied over the first end portion 109a) whilst still being sealed between the insulating layers 108b. In the embodiment shown in Figure IOC, the conductive track 108 is adhered to the fabric 201 using an adhesive layer 113 (shown in hatching).

The first end portion 109a is or comprises a shape and size substantially similar to the shape and size of the first portion 101 of the electrode, and preferably is slightly larger than the first portion 101. Preferably the first end portion 109a is larger (e.g., wider) than the rest of the conductive layer 108a, as shown in Figure 10D. In some embodiments, the first end portion 109a comprises a width of between substantially 2 to 5cm, depending on a required size of the first portion 101 of the electrode 100. The first end portion 109a may alternatively comprise a width of between substantially 2 to 5 times a width of a body portion 111 (described below with respect to Figures 11A and 11B) of the conductive track 108. This can help to maximise an area of conductive contact between the end portion 109a and the first portion 101 of the electrode 100, whilst minimising electrical resistance of the conductive track 108. In the embodiment shown, the first portion 101 and the first end portion 109a of the conductive layer 108a each comprise a substantially circular shape. The first end portion 109a of the conductive layer 108a of the conductive track 108 provides an improved electrical contact to the first portion 101 of the electrode 100. A resistance of the conductive layer 108a may be less than 30a The conductive layer 108a may improve or strengthen transmission of the electrical signals picked up by the first portion 101 of the electrode 100 to an external device (e.g., acquisition electronics such as a processor or transmitter).

In some embodiments, the conductive layer 108a comprises a second end portion 1091), as shown in Figures 10B, 10C and 10D. The second end portion 109b is configured to provide an electrical connection to an external device, for example, acquisition electronics used to record and analyse the electrical signals picked up by the electrode 100 and transmitted via the conductive track 108. In embodiments where the conductive layer 108a is sealed between insulating layers 108b, the second end portion 109b is also left exposed on a surface furthest from the fabric 201, similar to the first end portion 109a, as shown in Figures 10B and 10C.

The second end 109b may also be larger (e.g. wider) than the rest of the conductive layer 108a. The second end 109b may be smaller (e.g. narrower) than the first end 109b.

Typically, standard ECG electrodes arc fitted to a standard ECG cable using a press-stud or popper on the standard ECG electrode, the press-stud or popper configured to engage a corresponding recess on an end of the standard ECG cable (commonly known as a 'snap-fit' connection). In some embodiments, the second end portion 109b comprises a press-stud or popper or the like. The press-stud or popper of the second end portion 109b is configured to engage with a corresponding recess in an end of a standard ECG cable to form a physical and electrical connection with the ECG cable. The ECG cable is connectable or connected to acquisition electronics. In some embodiments, stability of the electrical connection is improved to reduce noise of the electrical signal measured by the electrode 100. Movement of a user wearing the garment 200 may result in movement of the ECG cable, or movement of the press-stud relative to the end of the ECG cable (e.g., rotational movement, axial movement) which may introduce noise and degrade the quality of the measured electrical signal. In some embodiments, a layer of encapsulating material (e.g., vinyl, polyurethane) is disposed over the second end portion 109b after connection of the end of the ECG cable to the press-stud of the second end portion 109b. The layer of encapsulating material adheres to the press stud of the second end portion 109b, and at least a portion of the ECG cable (including the end of the ECG cable connected to the press-stud), thereby preventing or reducing movement of the ECG cable or the press-stud relative to the end of the ECG cable. The layer of encapsulating material may also adhere to at least one of the entirety of the second end portion 109b, and the fabric 201. In some embodiments, the layer of encapsulating material is heat transferred onto the garment 200. In some embodiments, a length of the ECG cable between the second end portion 109b and the acquisition electronics is minimised to mitigate the introduction of noise into the electrical signal measured by the electrode 100.

Alternatively, in some embodiments the conductive track 108 is configured to interface or connect with acquisition electronics directly. For example, in some embodiments, a press-stud or popper (or other alternative physical and electrical connection mechanism) 114 located on the second end portion 109b of the conductive track 108 is configured to engage with a corresponding recess 313 (or other alternative connection mechanism) in an acquisition electronics unit 300, as shown in Figure 12A. The acquisition electronics may be disposed in or on the garment 200 (for example, on an interior surface of the garment 200). The conductive track 108 may extend from the electrode 100 to the acquisition electronics. In some embodiments, two or more electrodes 100 are incorporated into the garment. In such embodiments, the conductive tracks 108 of each of the two or more electrodes 100 extends and converges on the location of the acquisition electronics on the garment 200, such that each conductive track 108 interfaces or connects with the acquisition electronics directly. in alternative embodiments, a conductive yarn or thread 415 may be used in place of a conductive track to transmit electrical signals measured by the electrode 100, as shown in Figure 12B. In the embodiment shown, the conductive yarn 415 connects the electrode 100 to a press-stud or popper (or alternative connection mechanism) configured to engage with an ECG cable or directly with an acquisition electronics unit 300. In some embodiments, the conductive yarn 415 is stitched or embroidered into the fabric. In some embodiments, the conductive yarn 415 may be used to affix the press-stud to the fabric 201 (for example, by stitching the press-stud to the fabric 201). Alternatively, the conductive yarn 415 may be affixed to a surface of the fabric 201, for example using an adhesive.

A further alternative embodiment is depicted in Figure 12C. The conductive track 108 may be affixed to the fabric 201 except for the second end portion 109b. A conductive strip 416 is affixed to and electrically connected to the second end portion 109b of the conductive track 108. In some embodiments, the second end portion 109b is affixed to the conductive strip 416 using an adhesive (for example, a conductive adhesive). The conductive strip 416 comprises, in some embodiments, a polymeric material (for example, polyurethane or polyethylene terephthalate (PET) on which a conductive material (for example, a conductive ink such as copper ink or silver ink) can be disposed (for example, by screen printing). The conductive strip 416 provides an electrical connection between the second end portion 109b of the conductive track 108 and an acquisition electronics unit 300. Figure 12D shows a similar embodiment in which a conductive yarn 415 is used to transmit electrical signals measured by the electrode 100. The conductive yarn 415 is connected to a conductive strip 416 which provides an electrical connection between the conductive yarn 415 and an acquisition electronics unit 300. In sonic embodiments, the conductive yarn 415 is stitched or embroidered into at least one of the fabric 201 and the conductive strip 416. Alternatively, the conductive yarn 415 may be connected to at least one of the fabric 201 and the conductive strip 41 using an adhesive (for example a conductive adhesive). The hatched areas on the conductive strip 416 and the acquisition electronics unit 300 respectively in Figures 12C and 12D represent conductive contacts which are configured to form an electrical connection between the conductive strip 416 and the acquisition electronics unit 300.

In another alternative embodiment, the fabric 201 may comprise a pocket 202, as shown in Figures 12E and 12F respectively. A conductive track 108 (Figure 12F) or a conductive yarn 415 (Figure 12E) is affixed to the fabric 201 (for example, adhered, stitched or embroidered to the fabric 201). The conductive track 108 or conductive yarn 415 extends from the electrode 100 to an internal surface of the pocket 202. The second end portion 109b of the conductive track 108, or an end of the conductive yarn 415 is therefore located in the pocket 202. In some embodiments, the end of the conductive yarn 415 is arranged on (e.g., affixed to or stitched or embroidered into) the fabric 201 to maximise a surface area configured to form an electrical contact. For example, the end of the conductive yarn 415 may be arranged in a circular or spiral pattern to maximise an area of electrical contact. The second end portion 109b of the conductive track 108, or the end of the conductive yarn 415 are configured to form an electrical connection with conductive contacts (shown using hatching) on an acquisition electronics unit 300 (as indicated by the arrows between those features). The acquisition electronics unit 300 is configured to be located inside the pocket 202 of the fabric 201. Once located in the pocket 202, the conductive contacts of the acquisition electronics unit 300 are brought into contact with the second end portion 109b of the conductive track or the end of the conductive yarn 415. The pocket 202 may perform two functions. The pocket 202 locates the acquisition electronics unit 300 securely on a garment 200 comprising the fabric 201. The pocket 202 also applies pressure to ensure a consistent, reliable electrical connection between the acquisition electronics unit 300 and the second end portion 109b of the conductive track 108 or the end of the conductive yarn 415. These effects are enhanced in embodiments in which the fabric 201 comprises a compression fabric.

The skilled person will appreciate that a combination of any of the features described with respect to Figures 12A to 12F may be employed to connect the electrode 100 to the acquisition electronics. For example, in some embodiments, a pocket 202 is used to locate an acquisition electronics unit 300, in conjunction with a conductive track 108 or conductive yarn 415 which extends into the pocket 202 and which is connected to a press-stud (or other connection mechanism) configured to engage with a corresponding engagement feature on the acquisition electronics unit 300.

In sonic embodiments comprising a conductive track 108, the first portion 101 is not applied to the fabric 201 (or at least is not in full contact with the fabric 201). Instead, the first portion 101 of the electrode 100 is applied over the first end portion 109a of the conductive track 108, in a manner substantially similar to that described above for applying the first portion 101 to the fabric 201. The first portion 101 of the electrode 100 is sized and located over the first end portion 109a so that it does not fully cover the first end portion 109a, and does not extend beyond a perimeter of the first end portion 109a. In some embodiments, one or more apertures 110 are provided in or near to the first end portion 109a of the conductive layer 108a (with corresponding aperture(s) 110 also provided in the insulating layer 108b nearest to the fabric 201), as shown in Figure 11A. In the embodiment shown, a plurality of apertures 110 is provided. The apertures 110 comprise a variety of shapes and sizes (e.g., arc shaped apertures, circular apertures, rectangular apertures). Alternatively, the apertures 110 may each be or comprise the same shape and size. The apertures 110 are positioned around a perimeter of the first end portion 109a, in a centre of the first end portion 109a, and/or at the 'neck' region of the conductive track 108 where the first end portion 109a begins. The apertures 110 allow uncured or partially cured material of the first portion 101 to both bond to the conductive track 108 and wick into the fabric 201, improving adhesion of the electrode to the fabric 201. In particular, the apertures 110 may prevent delamination or peeling of the electrode 100 or the conductive track 108 away from the fabric 201 at the 'neck' region of the conductive track (where the first end portion 109a begins). However, the apertures 110 are sized and positioned in the conductive track 108 so as to minimise impact on the electrical properties of the conductive track 108 or the electrical contact between the conductive laver 108a and the first portion 101 of the electrode 100. Alternatively, if the first portion 101 is pre-cured or cut from a sheet of material, the apertures 110 may allow adhesive to secure or adhere the first portion 101 to both the conductive track 108 and the fabric 201, again improving adhesion of the electrode 100 to the fabric 201.

The second portion 102 of the electrode 100 is also provided on or applied on or over the first end portion 109 of the conductive track 108. The second portion 102 is provided on or applied in a manner substantially similar to that described above for applying the second portion 102 to the fabric 201. The second portion 102 is applied so that it is in contact with both the first end portion 109a (where the first end portion 109a is not covered by the first portion 101 of the electrode 100) and the fabric 201. This allows the second portion 102 to adhere to or be bonded to the first portion 101, the first end portion 109a of the conductive track 108, and the fabric 201. This arrangement may improve the robustness of the electrode 100 when affixed to the fabric 201.

The conductive track 108 comprises a body portion 111, as illustrated in Figures 11A and 11B. The body portion 111 extends away from the first end portion 109a (and therefore away from the electrode 100) across the fabric 201, in the embodiment shown in Figure 11A, the body portion 111 is or comprises a substantially straight, elongated shape. Figure 11B shows an embodiment of a body portion 111 that is generally elongate but which is or comprises one or more bends or curves 112. The one or more bends or curves 112 of the body portion 111 may enable the conductive track 108 to more easily accommodate movement of the fabric 201 to which the conductive track 108 is applied, without causing movement of the electrode 100 to which the conductive track 108 is attached.

The conductive track 108 may be applied to the fabric 201 using a number of techniques. In some embodiments, the conductive track 108 is pre-fabricated and subsequently heat transferred onto the fabric 201. The conductive track 108 may be pre-fabricated with the insulating layers 108b surrounding and sealing the conductive layer 108a (except for an exposed first end portion 109a and second end portion 109b of the conductive layer 108a). For example, a first insulating layer 108b, a conductive layer 108a and a second insulating layer 108b may be disposed (e.g., printed) layer by layer onto heat-transfer sheet material. In some embodiments, each layer is less than 100 gm in thickness. in some embodiments, each layer is cured before application of the next laver. Each laver may be cured at a temperature of substantially 130°C for a time of substantially 2 minutes, although the skilled person will recognise that different material formulations may require different curing times and curing temperatures. Alternatively, each layer may be cured using at least one of heat, pressure and UV irradiation. The pre-fabricated conductive track 108 may then be heat transferred to the fabric 201 by applying heat (and optionally pressure) to the heat-transfer sheet material whilst the conductive track 108 is in contact with the fabric 201 (for example, using a heated press). A heat-activated fabric adhesive may be disposed between the conductive track 108 and the fabric 201 prior to applying heat (and optionally pressure) to the heat-transfer sheet material.

The heat-activated fabric adhesive may be activated using a temperature of substantially 160°C for a time of between 10 seconds and 15 seconds (or for between substantially 5 and 30 seconds at a temperature of between substantially 120 and 200°C). The heat-transfer sheet material may then be removed, leaving the conductive track 108 affixed to the fabric 201.

Alternatively, individual layers of the conductive track 108 may be pre-fabricated separately and heat transferred onto the fabric 201 layer by layer. In other embodiments, the conductive track 108 is screen printed onto the fabric 201. Insulating layers 108b and conductive layer 108a of the conductive track 108 are screen printed layer by layer. Applying the separate layers to the fabric 201 directly one after another prevents a rippling effect which tends to occur if too long a delay between subsequent layers being applied occurs.

In some embodiments, the conductive track 108 is itself encapsulated in additional layers (for example, a waterproof membrane), rather than being affixed directly to the fabric 201 (for example, using an adhesive). In alternative embodiments, a conductive yarn or wire (e.g., stitched or embroidered into the fabric 201) may be used in place of the conductive track 108.

Signal Analysis An ECG signal measured using one or more electrodes 100 may be acquired from acquisition electronics connected to the electrode(s) 100 as described above. The data forming the ECG signal may be periodically uploaded (e.g., at substantially regular time intervals of between substantially every 3 to 30 seconds, for example substantially every five seconds or substantially every 10 seconds) to the internet (e.g., via an HTTP connection). The data may be transferred from the acquisition electronics to an external device wirelessly, for exampling using Bluetootht Low Energy. The data that is uploaded comprises time-series data that is proportional to a voltage or potential difference measured by the acquisition electronics between one or more pairs of electrodes 100. In some embodiments, frequency-based filtering (c.g., to remove high-frequency, noise, or to correct a wandering baseline) may be performed by the acquisition electronics prior to the ECG signal being uploaded to a web server. Once the ECG signal data is uploaded, the ECG signal data may be saved into a time-series database and processed.

In an embodiment, to enable real-time internet based collection and processing of ECG signals, multiple software elements may be used. The software elements may include embedded software, mobile application software (e.g., Android mobile application software) and cloud based software (e.g., python cloud based software).

The embedded software may implement a driver that is able to communicate with electrodes (for example, electrodes 100). Data (e.g., electrical signals measured by the electrodes 100) may be transmitted or read into the acquisition electronics (e.g., an ARM microcontroller) and then presented on, for example, a Bluctooth Low energy wireless interface.

Mobile application software may connect to a device (for example a mobile communications device) using the Bluctooth Low Energy interface, and subscribe to custom characteristics that allow the measured ECG data to be streamed to the mobile application software from the acquisition electronics. The data may be buffered locally and then uploaded to a cloud based system, for example using HTTP. Alternatively, the acquisition electronics may communicate directly with the cloud based system, rather than using a device as an intermediary. A device may be used as an intermediary if, for example, battery life of the acquisition electronics is low or needs to be preserved, if no or a poor internet connection is available, or if there is only a relatively small amount of data to transfer (e.g., transferring large amounts of data using the Bluetooth interface can be impractical). A device may also be used as a user interface to the acquisition electronics, for example to request a data update, or request an alert if something of high-importance is measured or occurs, or to conduct system checks.

The cloud based software may implement a server (e.g.. an HTTP server) that authenticates the source of the data, and then puts the data message onto an AMQP message bus. Python based agents may monitor the message bus using the Pica library and take messages to be processed.

An ECG Annotation Worker (for exampling, written using Python) may be alerted when new data is added to the database, and may utilise a suitable amount of recently added data (for example, between 1 and 10 seconds worth of recently added data, or between 1 and 10 data uploads of recently added data) from the database for processing. The first element of processing carried out by the ECG Annotation Worker may be identification of R-peaks in the ECG signal. This may be done, for example, using a biosignal processing library such as BioSPPy. Default parameters within the signals.ecg module within BioSPPy may be used to identify or locate R-peaks in the ECG signal (for example by calling, filtered, r peaks" , heart_rate = biosppy.signals.ecg.ecg(ecg_data.ecg_v, sample_rate, show=False). In some embodiments, the ECG signal is filtered prior to analysis. For example, the ECG signal may be subjected to frequency-based filtering (e.g., to remove high-frequency noise, or to correct a wandering baseline). in some embodiments, the BioSPPy library performs the filtering of the ECG signal. However, in some embodiments, the ECG signal is not filtered prior to signal analysis. The reason for this is that filtering can introduce deformation to some parts of the ECG signal, such as the T Wave, in some embodiments, both a filtered version of the ECG signal and an unfiltered version of the ECG signal (i.e., the raw ECG signal) are analysed as described further below to identify features in the ECG signal.

The time-series data that represents the ECG signal may be stored as an array of values, which can each be accessed using an index. Positions or locations of the R-peaks in the ECG signal that have been located or identified using the biosignal processing library may also be stored. Based on the position or location of he R-peaks in the ECG signal, other important features in the ECG signal may be identified, for example: a start position of a QRS complex; an end position of a QRS complex; a QRS complex duration; a start position of a P wave; a PR interval: a start position of a T Wave; a start position of an ST segment; an end position of an ST segment; an ST segment duration; an end position of a T wave; a start position of a QT interval; an end position of a QT interval; and a QTc interval.

Such additional features of the ECG signal may be determined by identifying indexes (i.e., a position or location) within the lime-series data where the ECG signal (or a higher-order derivative of the ECG signal) transitions through zero on the y-axis. The y-axis of the ECG signal represents voltage, whilst the x-axis of the ECG signal represents time.

During different orders of differentiation of a mathematical signal, wave peaks (and inflection points in the original signal) will cross the zero-point of the y-axis. This can be used to provide a method of identifying signal peaks and inflections. Differentiating an ECG signal and looking for a particular zero-crossing point on the resulting signal relative to a reference point (e.g., an R-peak) in the original ECG signal may be used to identify features in the ECG Figure 13 illustrates this concept in greater detail. [represents an original signal, .1 represents a first order derivative off, and f" represents a second order derivative off It can be seen that the peak of the first wave in] aligns with a zero crossing in/ (approximately 16 on the x-axis). Similarly, the falling inflection point in f aligns with a zero-crossing point in f' (approximately 30 on the x-axis). In Figure 13,1 and / ' have been scaled up to more clearly illustrate the zero-crossing points.

In one embodiment, the ECG signal is segmented by taking a segment of the ECG signal with two sequential or adjacent R-peaks forming ends of the segment. In other embodiments, the ECG signal is segmented by taking a segment comprising three or more adjacent or sequential R-peaks. The segmented ECG signal is then processed by determining one or more zero-crossing points (e.g., n zero-crossing points) in one or more order differentials of the ECG signal. An nth order differential of the ECG signal may be a zeroth, first, second or higher order differential. In some embodiments, zero-crossing points arc determined at positions in the ECG signal prior to a reference point (e.g., an R-peak) in the ECG signal (e.g., identifying features which appear earlier in time than a reference point in the ECG signal, or leftward of the reference point with respect to the x-axis). In other embodiments, zero-crossing points are determined at positions in the ECG signal after a reference point (e.g., an R-peak) in the ECG signal (e. ., identifying features which appear later in time than a reference point in the ECG signal, or rightward of the reference point with respect to the x-axis).

For example, relative to an identified R-peak index position, a start position of a QRS complex in an ECG signal may be identified by determining a position of the second zero crossing point, prior to the position of the R-peak, in the second order differential of the ECG signal. The second zero crossing point in the second order differential of the ECG signal prior to the position of the R-peak in the ECG signal means the zero-crossing point in the second order differential of the ECG signal which has the second smallest difference in position relative 10 the R-peak in the ECG signal. Relative to an identified R-peak position index, an end position of the QRS complex may be identified by determining a position of the second zero-crossing point, after the position of the R-peak, in the zeroth order differential of the ECG signal (i.e., a non-differentiated ECG signal). The second zero crossing point in the zeroth order differential of the ECG signal after the position of the R-peak in the ECG signal means the zero-crossing point in the zeroth order differential of the ECG signal which has the second smallest difference in position relative to the R-peak in the ECG signal. Once the positions or indexes of the start position and the end position of the QRS complex have been determined, the QRS complex duration may be calculated simply.

Other important features in the ECG signal may be identified in a similar manner, by searching for positions of zero-crossing points in various 11th order differentials of the ECG signal relative to a position of a known feature (i.e., a reference point) in the ECG signal. A position of the R-peak has been used as the reference point in the above example, but the skilled person will appreciate that any feature in an ECG signal may be used as a reference point for identifying other features in the ECG signal using this approach.

In some embodiments, a previously determined zero-crossing point in an nth order differential of the ECG signal is used as an updated reference point for identifying other features in the ECG signal. For example, to determine a QT interval, a position of the fourth zero-crossing point, after a start position of a T wave, in the second order differential of the ECG signal may be used to determine a position (e.g., an estimated position) of a peak of a T wave in the ECG signal. The position of the peak of the T wave may then be used as a reference point to determine a position of an end of the T wave using the approach described above (e.g., determining a position of a zero-crossing point in an nth order differential of the ECG signal relative to a position of a reference point in the ECG signal). In some embodiments, an end position of the T wave is identified by determining a second zero-crossing point (after the position of the peak of the T wave in the ECG signal) of a second order differential of the ECG signal.

An annotation array of the same length as the ECG signal array may also be created, with annotations for key features in the ECG signal contained in the annotation array. The annotation array may enable the key features in the ECG signal to be annotated in a graphical representation of the ECG signal (e.g., a start position of the QRS complex may be annotated Q', and an end position of the QRS complex may be annotated 'S').

The processed annotated data may then be published to an MQTT based message broker that could be subscribed to by other applications, such as a website that implements a graphical user interface (GUI) or display that renders the raw signal, processed signal and annotations to a user.

In some embodiments, a QTc interval is identified by dividing an identified QT interval in the ECG signal (e.g., a time period or difference in position in the ECG signal between the start position of the QRS complex and the end position of the T wave in the ECG signal) by a square root of an interval between successive R-peaks in the ECG signal (e.g., a time period or different in position in the ECG signal between successive R-peaks in the ECG signal).

In addition to feature identification in an ECG signal as described above, in some embodiments the ECG signal is analysed and/or processed to identify the presence of features such as ectopic heartbeats in the ECG signal. in some embodiments, features such as ectopic heartbeats in the ECG signal are identified by identifying an R-peak having a position in the ECG signal that occurs significantly before an expected position of the R-peak in the ECG signal based on a current heart rate. For example, a position of each of a plurality of R-peaks in the ECG signal (for example, three or more R-peaks) may be identified. The distances between the positions of each of the plurality of R-peaks in the ECG signal may be measured or determined. If between, for example, three consecutive or adjacent R-peaks in the ECG signal, a middle R-peak of the three R-peaks in the ECG signal has a position significantly before an expected position of that R-peak in the ECG signal, that middle R-peak may be identified as an ectopic heartbeat in the ECG signal. The ECG signal may then be annotated to indicate the ectopic heartbeat in the ECG signal. In some embodiments, a threshold for determining whether an 12-peak in the ECG signal has a position significantly before an expected position of the R-peak in the ECG signal is set equal to a value of between substantially 0.4 and substantially 0.8, or substantially 0.6, of an expected relative distance of the R-peak from the previous R-peak in the ECG signal. In some embodiments, the threshold is referred to as an ectopic interval ratio. In some embodiments, the threshold is determined empirically from available data. The skilled person would appreciate that a similar approach may be employed using other features in an ECG signal, for example a P wave or a T wave in the ECG signal. An advantage of using R-peaks is that there is a reduced susceptibility to noise, as an R-peak is typically the feature having the largest amplitude in an ECG signal.

An alternative approach for identifying features such as ectopic heartbeats in the ECG signal is determining an interval between two successive pairs of R-peaks in the ECG signal (i.e., with a middle R-peak in the ECG signal common to each of the pairs of R-peaks in the ECG signal). If dividing one of the intervals by the other of the intervals is less than a threshold (for example, a value of between substantially 0 4 and substantially 0.8, or substantially 0.6), the middle R-peak in the two successive pairs of R-peaks in the ECG signal may be identified as an ectopic heartbeat.

In some embodiments, a characteristic such as heart rate variability is determined using the identified positions of a plurality of R-peaks in the ECG signal. For example, a technique known as Root Mean Square of Successive Differences (RMSSD) may be applied to successive R-peaks in the ECG signal to determine the heart rate variability (for example in m I iseco nds).

Figure 14 shows an embodiment of a method 500 for processing or analysing an ECG signal. The method starts at step 501. At step 502, an ECG signal is received from a device. For example, cloud based software may receive an ECG signal from a processor, computer or other device connected directly or indirectly, using wires or wireless's', to electrodes measuring electrical signals produced by a person to produce the ECG signal. At step 503, the ECG signal is filtered (for example using a biosignal processing library such as BioSPPy), and a position of one or more features in the ECG is detected. In some embodiments, a position of one or more R-peaks in the ECG signal is detected. In some embodiment, the ECG signal is not filtered before features in the ECG signal are detected. At step 504, one or more th n order differentials of the ECG signal are created. In some embodiments, a zeroth order differential, a first order differential and a second order differential of the ECG signal are created. In other embodiments, higher order differentials of the ECG signal are additionally or alternatively created.

At step 505, a start position and an end position of a QRS complex in the ECG signal is identified. In sonic embodiments, a position of the second zero-crossing point in the second order differential of the ECG signal prior to the position of a known R-peak in the ECG signal is used to indicate or identify a start position of a QRS complex in the ECG signal. In some embodiments, a position of the second zero-crossing point in the zeroth order differential of the ECG signal after the position of a known R-peak in the ECG signal is used to indicate or identify an end position of a QRS complex in the ECG signal. At step 506, a duration of a QRS complex in the ECG signal is calculated. In some embodiments, a duration of a QRS complex is calculated by determining a difference in position in the ECG signal of a start position of a QRS complex identified relative to a position of a known R-peak, and an end position of a QRS complex identified relative to the position of the same known R-peak.

At step 507, a start position of a P wave in the ECG signal is identified. In some embodiments, a position of the eighth zero-crossing point, prior to a start position of a QRS complex in the ECG signal, in the second order differential of the ECG signal is used to identify a start position of a P wave in the ECG signal At step 508, a PR interval in the ECG is calculated. In sonic embodiments, a PR interval in the ECG signal is calculated by determining a difference in position in the ECG signal of a start position of a P-wave relative to a position of a known R-peak.

At step 509, a start position of a T wave in the ECG signal is identified. In some embodiments, a start position of a T wave in the ECG signal is identified by determining a position of the fifth zero-crossing point, after an end position of a QRS complex in the ECG signal, in the third order differential of the ECG signal. At step 510, an ST segment duration in the ECG signal is calculated. In some embodiments, an ST segment duration in the ECG signal is calculated by determining a difference in position in the ECG signal of a start position of a T wave relative to an end position of a QRS complex (e.g., an end position of a QRS complex in the ECG signal which is prior to a start position of the T wave in the ECG signal).

Al step 511, a position in the ECG signal of a peak of a T wave in the ECG signal is estimated. In sonic embodiments, a position of a peak of a T wave in the ECG signal is determined by determining a position of the fourth zero-crossing point, after a start position of a T wave in the ECG signal, in the second order differential of the ECG signal. At step 512, an end position of a T wave in the ECG signal is identified. In some embodiments, an end position of a T wave in the ECG signal is identified by determining the second zero-crossing point, after a position of a peak of a T wave in the ECG signal, in the second order differential of the ECG signal. At step 513, a QT interval in the ECG signal is calculated. In some embodiments, a QT interval in the ECG signal is calculated by determining a difference in position in the ECG signal of a start position of a QRS complex relative to an end position of a T wave (e.g., a start position of a QRS complex in the ECG signal which is prior to an end position of a T wave in the ECG signal).

At step 514, an R-peak interval in the ECG signal is calculated. In sonic embodiments, a difference in position in the ECG signal of successive R-peaks is used to calculate the R-peak interval. At step 515, a QTc interval in the ECG signal is calculated. In some embodiments, a QTc interval in the ECG signal is calculated by dividing a calculated QT interval by a square root of the calculated R-peak interval. A QTc interval is calculated to determine a QT interval that is corrected for heart rate.

At step 516, ectopic beats in the ECG signal are identified. In some embodiments, the step of identifying ectopic beats in the ECG signal is not performed. In some embodiments, ectopic beats in the ECG signal are identified separately from the identification of other features in the ECG signal. For example, ectopic beats in the ECG signal may be identified once an R-peak interval in the ECG signal is calculated (see step 514). Calculating an R-peak interval in the ECG signal may be performed directly after step 503. Steps 504 to 513 are not essential for the identification of ectopic beats in the ECG signal. In some embodiments, ectopic beats in the ECG signal are identified substantially as described above. At step 517, a heart rate variability in the ECG signal is calculated. In some embodiments, a heart rate variability in the ECG signal is calculated as describe above. For example, a heart rate variability in the ECG signal may be calculated using the Root Mean Square of Successive Difference technique and applying that technique to successive R-peaks in the ECG signal. The heart rate variability in milliseconds may be calculated using such a technique.

As described above, the processed or analysed ECG signal may be annotated to indicate a position of identified features in the ECG signal It should be noted that the above methods may be utilised for both diagnostic and non-diagnostic methods. With regard to non-diagnostic methods, an ECG signal may be processed as outlined above in order to identify one or more specific features of an ECG without attributing the presence or absence of any features in the ECG signal to a clinical picture (whether broad or specific). In this regard. a non-diagnostic method in accordance with the above signal analysis or processing methods may be used simply to annotate data, for example for training or teaching purposes.

Figure 15 shows a system 600 for measuring, and identifying features in, an ECG signal. The system 600 comprises one or more electrodes 601 for measuring electrical signals produced by a person. In some embodiments, the electrodes 601 are or comprise one or more electrodes 100 as described above. The system 600 also comprises a processor 602. The processor 602 may be configured to receive an ECG signal from the one or more electrodes 601. The dashed lines in Figure 15 running from the electrodes 601 to the processor 602 indicate a direct or indirect connection between those components of the system 600. The processor 602 may also be configured to determine a position or one Or More zero-crossing points in one or ITIOre /76 order differentials of the ECG signal relative to a position of at least one known feature in the ECG signal. The processor 602 may further be configured to attribute each zero-crossing point to a feature in the ECG signal based on a position of the one or more zero-crossing points in the one or more nth order differentials of the ECG signal relative to the position of the known feature in the ECG signal.

In some embodiments, the processor 602 is further configured to perform any methods described above with respect to data analysis or processing of an ECG signal. For example, the processor 602 may be configured to filter the ECG signal to remove a high-frequency noise component, or to correct a wandering baseline. In particular, the processor 602 may be configured to produce an annotated ECG signal by annotating the ECG signal at positions in the ECG signal corresponding to identified features in the ECG signal. For example, the processor 602 may be configured to produce an annotation array of the same length as the ECG signal array, with annotations for key features in the ECG signal contained in the annotation array. The annotation array may enable the key features in the ECG signal to be annotated in a graphical representation of the ECG signal (e.g., a start position of the QRS complex may be annotated Q'). In some embodiments, the system 600 further comprises a display 603. The display 603 is configured to display at least one of the ECG signal, a filtered version of the ECG signal, and annotations or an annotated version of the ECG signal. The display 603 may be a display screen such as an LCD display screen or an LED display screen.

The dashed lines in Figure 15 running from the processor 602 to the display 603 indicate a direct or indirect connection between those components of the system 600.

From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art of electrodes and/or signal processing or analysis (for example, ECG signal processing or analysis), and which may be used instead of, or in addition to, features already described herein.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. Thc applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom. Features of the devices and systems described may be incorporated into/used in corresponding methods.

For the sake of completeness, it is also stated that the term "comprising" does not exclude other elements or steps, the term "a" or "an" does not exclude a plurality, a single processor or other unit may fulfil the functions of several means recited in the claims and any reference signs in the claims shall not be construed as limiting the scope of the claims.

The following clauses (not claims) are statements defining aspects of the invention.

1. An electrode for measuring electrical signals produced by a person, the electrode cornprising: a first portion configured to form an electrical connection directly with skin of the person to measure electrical signals; and a second portion configured to grip to the skin to prevent movement of the electrode during measurement of electrical signals.

2. The electrode of clause 1, wherein (he firs( portion and the second portion together form a surface configured to contact an area of skin of the person during measurement of electrical signals.

3. The electrode of clause 2, wherein the surface comprises: an inner region that is or comprises the first portion; and an outer region that is or comprises the second portion, wherein the outer region at least partially surrounds the inner region, and optionally wherein the inner region and the outer region are or comprise substantially the same shape and/or configuration.

The electrode of clause 3, wherein: the inner region is or comprises a substantially circular shape; and the outer region is or comprises: i) one or more arcs concentric with the inner region or a ring concentric with the inner region.

5. The electrode of any preceding clause, wherein the second portion is shaped and/or configured to create a suction effect to grip to the skin.

6. The electrode of any preceding clause, wherein the second portion comprises a textured surface to grip to the skin to prevent movement of the electrode during measurement and, optionally, the first portion comprises a textured surface to grip to the skin to prevent movement of the electrode during measurement.

The electrode of any preceding clause, wherein at least a part of the first portion is porous and/or wherein at least a part of the first portion is or comprises carbonised silicone.

8. The electrode of any preceding clause, wherein at least a part of the first portion and/or the second portion is or comprises a biocompatible material.

9. The electrode of any preceding clause wherein at least a part of the second portion is Of comprises silicone.

10. A garment comprising at least one electrode according to any of clauses 1 to 9, wherein the at least one electrode is integral with and/or is located on an interior surface of the garment when the garment is worn by a person, and optionally wherein the garment comprises an elastic material configured to apply compression to skin of a person such the at least one electrode grips to the skin when the garment is worn by the person.

11. The garment of clause 10, wherein the at least one electrode is located such that the electrode is configured to obtain an EMG signal of one or more muscles of a person when the garment is worn by the person.

12. The garment of clause 10, wherein the at least one electrode is located such that the electrode is configured to obtain an ECG signal of a person when the garment is worn by the person, and optionally wherein the garment is a top, and further optionally wherein the garment comprises at least two electrodes, and optionally comprises three, four, five, six, seven, eight, nine, ten or more electrodes, and further optionally wherein the electrodes are located on the interior surface of the garment such that a potential difference across a heart of the person is measurable in at least one direction when the garment is worn by the person.

13. The garment of clause 10, wherein the garment is an item of headwear configured to obtain an EEG signal of a person when the item of hcadwear is worn by the person. 25 14. The garment of any preceding garment clause, wherein the garment comprises an electrically conductive track electrically connected at a first end to the first portion of the at least one electrode, and optionally wherein the conductive track is disposed between the interior surface of the garment and the first portion of the electrode, and optionally wherein the conductive track is affixed to the interior surface of the garment.

15. The garment of clause 14, wherein the conductive track is encapsulated in a waterproof membrane, and optionally wherein the waterproof membrane is affixed to the interior surface of the garment.

16. A method of identifying features in an ECG signal, the method comprising: determining a position of one or more zero-crossing points in one or more nth order differentials of the ECG signal relative to a position of at least one known feature in the ECG signal; and identifying one or more features in the ECG signal by attributing each zero-crossing point in the one or more nth order differentials of the ECG signal to a feature in the ECG signal based on the position of each zero-crossing point in the one or more nth differentials of the ECG signal relative to the position of the known feature in the ECG signal.

17. The method of clause 16, wherein the at least one known feature in the ECG signal is or comprises one or more known R-peaks in the ECG signal.

18. The method of clause 17, further comprising: determining positions of zero-crossing points of a second order differential of the ECG signal prior to a position of a known R-peak in the ECG signal; and identifying a start position of a QRS complex in the ECG signal by attributing the zero-crossing point of the second order differential of the ECG signal having the second-smallest difference in position relative to the position of the known R-peak in the ECG signal to a start position of a QRS complex in the ECG signal; and/or.

determining positions of zero-crossing points of a zeroth order differential of the ECG signal after a position of a known R-peak in the ECG signal; and identifying an end position of a QRS complex in the ECG signal by attributing the zero-crossing point of the zeroth order differential of the ECG signal having the second smallest difference in position relative to the position of the known R-peak in the ECG signal to an end position of a QRS complex in the ECG signal.

19. The method of any preceding method clause, further comprising filtering the ECG signal prior to identifying features in the ECG signal, and optionally filtering the ECG signal to remove high-frequency noise from the ECG signal and/or to correct a wandering baseline of the ECG signal, and further optionally comprising identifying features in both the ECG signal and the filtered ECG signal.

20. The method of any preceding method clause, further comprising: determining a position of one or more further zero-crossing points in one or more nth order differentials of the ECG signal relative to a position of one or more previously determined zero-crossing points in one or more ni order differentials of the ECG signal: and identifying features in the ECG signal by attributing each further zero-crossing point in the one or more nth order differentials of the ECG signal to a feature in the ECG signal based on the position of the one or more further zero-crossing points in the one or more nth order differentials of the ECG signal relative to the position of the one or more previously determined zero-crossing points in the one or more nth order differentials of the ECG signal.

21. The method of any preceding clause, wherein the one or more nth order differentials of the ECG signal comprise at least one of a zeroth order differential of the ECG signal, a first order differential of the ECG signal, a second order differential of the ECG signal, and a higher order differential of the ECG signal.

22. A system comprising: one or more electrodes for measuring electrical signals produced by a person; and a processor configured to: receive an ECG signal from the one or more electrodes; determine a position of one or more zero-crossing points in one or more nth order differentials of the ECG signal relative to a position of at least one known feature in the ECG signal; and identify one or more features in the ECG signal by attributing each zero-crossing point in the one or more nth order differentials of the ECG signal to a feature in the ECG signal based on the position of each zero-crossing point in the one or more nth differentials of the ECG signal relative to the position of the known feature in the ECG signal.

23. The system of clause 22, wherein each electrode is as set out in any of clauses 1 to 9.

24. The system of clause 22 or of clause 23, wherein the processor is further configured to perform the method of any of clauses 16 to 21.

25. The system of any preceding system clause, further comprising a display configured to display the ECG signal.

26. The system of any preceding system clause, wherein the processor is configured to produce an annotated ECG signal by annotating the ECG signal at positions in the ECG signal corresponding to identified features in the ECG signal.

27. The system of clause 26 as it depends from clause 25, wherein the display is configured to display the annotated ECG signal.

28. A method of identifying an ectopic heartbeat in an ECG signal, the method comprising: identifying a position of each feature in at least one pair of successive corresponding features in the ECG signal; determining a distance between the positions of each feature in each pair of successive corresponding features in the ECG signal; determining that an ectopic heartbeat is present in the ECG signal if the distance between the positions of each feature in a pair of successive corresponding features in the ECG signal is less than a threshold distance.

29. The method of clause 28, further comprising: identifying a position of each feature in at least two pairs of successive corresponding features in the ECG signal; determining an average distance between the positions of each feature in each pair of successive corresponding features in the ECG signal; determining that an ectopic beat is present in the ECG signal if the distance between each feature in a pair of successive corresponding features in the ECG signal is less than the average distance multiplied by a scaling factor, and optionally wherein the scaling factor is between substantially 0.4 and 0 8, and optionally is substantially 0.6.

3 0. The method of clause 28, further comprising: identifying a position of each feature in two successive pairs of successive corresponding features in the ECG signal, wherein the two successive pairs of successive corresponding features share a common feature; determining a distance between each feature in each pair of successive corresponding features in the ECG signal; determining that an ectopic beat is present in the ECG signal if the distance between each feature in the earlier pair of successive corresponding features in the ECG signal divided by the distance between each feature in the later pair of successive corresponding features in the ECG is less than the threshold, and optionally wherein the threshold is between substantially 0.4 and 0.8, and optionally is substantially 0.6.

31. The method of any of clauses 28 to 30 wherein the feature is or comprises one of an R-peak, a P wave or a T wave.

Claims

CLAIMS1. A garment comprising at least one electrode for measuring electrical signals produced by a person: wherein the at least one electrode is located on an interior surface of the garment when the garment is worn by, a person; and wherein the at least one electrode comprises: a first portion configured to form an electrical connection directly with skin of the person to measure electrical signals without conductive gel; and a second portion configured to grip to the skin without adhesive to prevent movement of the electrode during measurement of electrical signals.
2. The garment of claim 1. wherein the first portion of the electrode and the second portion of the electrode together form an electrode surface configured to contact an area of skin of the person during measurement of electrical signals.
3. The garment of claim 2, wherein the electrode surface comprises: an inner region that is or comprises the first portion; and an outer region that is or comprises the second portion, wherein the outer region at least partially surrounds the inner region, and optionally wherein the inner region and the outer region are or comprise substantially the same shape and/or configuration.
4. The garment of claim 3, wherein: the inner region is or comprises a substantially circular shape and the outer region is or comprises: i) one or more arcs concentric with the inner region; or ii) a ring concentric with the inner region.
5. The garment of any preceding claim, wherein the second portion of the electrode is shaped and/or configured to create a suction effect to grip to the skin.
6. The garment of any preceding claim, wherein the second portion of the electrode comprises a textured surface to grip to the skin to prevent movement of the electrode during measurement and, optionally, the first portion of the electrode comprises a textured surface to grip to the skin to prevent movement of the electrode during measurement.
7. The garment of any preceding claim, wherein at least a part of the first portion of the electrode is porous and/or wherein at least a part of the first portion of the electrode is or comprises carbonised silicone.
8. The garment of any preceding claim, wherein at least a part of the first portion of the electrode and/or the second portion of the electrode is or comprises a biocompatible material.
9. The garment of any preceding claim, wherein at least a part of the second portion of the electrode is or comprises silicone.
10, The garment of any preceding claim, wherein the at least one electrode is integral with the interior surface of the garment.
11. The garment of any preceding claim, wherein the garment comprises an elastic material configured to apply compression to skin of a person such the at least one electrode grips to the skin when the garment is worn by the person.
12. The garment of any preceding claim, wherein the at least one electrode is located such that the electrode is configured to obtain an EMG signal of one or more muscles of a person when the garment is worn by the person; and/or wherein the at least one electrode is located such that the electrode is configured to obtain an ECG signal of a person when the garment is worn by the person: and/or wherein the at least one electrode is located such that the electrode is configured to obtain an impedance measurement of tissue of a person when the garment is worn by the person.
13 The garment of any preceding claim, wherein the garment is a top, or wherein the garment is a pair of shorts, trousers, lights or leggings.
14. The garment of any preceding claim, wherein the garment comprises at least two electrodes, and optionally comprises three. four. five, six, seven, eight, nine, ten or more electrodes.
15. The garment of any preceding claim, wherein the electrodes are located on the interior surface of the garment such that a potential difference across an organ of the person is measurable in at least one direction when the garment is worn by the person, and optionally wherein the organ is a heart, a brain or a muscle of the person.
16. The garment of any preceding claim, wherein the electrodes are located on the interior surface of the garment such that impedance of at least one tissue of the person is measurable when the garment is worn by the person.
17. The garment of any preceding claim, wherein the garment is an item of headwear configured to obtain an EEG signal of a person when the item of headwear is worn by the person.
18. The garment of any preceding claim, wherein the garment comprises an electrically conductive track electrically connected at a first end to the first portion of the at least one electrode, and optionally wherein the conductive track is disposed between the interior surface of the garment and the first portion of the electrode, and optionally wherein the conductive track is affixed to the interior surface of the garment.
19. The garment of claim 18, wherein the conductive track is encapsulated in a waterproof membrane, and optionally wherein the waterproof membrane is affixed to the interior surface of the garment.