WO2022106833A1 - Procédé et système de détection de pics dans un biosignal - Google Patents

Procédé et système de détection de pics dans un biosignal Download PDF

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Publication number
WO2022106833A1
WO2022106833A1 PCT/GB2021/052998 GB2021052998W WO2022106833A1 WO 2022106833 A1 WO2022106833 A1 WO 2022106833A1 GB 2021052998 W GB2021052998 W GB 2021052998W WO 2022106833 A1 WO2022106833 A1 WO 2022106833A1
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Prior art keywords
signal
subject
threshold level
specific information
electronics module
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PCT/GB2021/052998
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English (en)
Inventor
Connor David DRISCOLL
Original Assignee
Prevayl Innovations Limited
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Application filed by Prevayl Innovations Limited filed Critical Prevayl Innovations Limited
Priority to GB2309258.8A priority Critical patent/GB2616763A/en
Publication of WO2022106833A1 publication Critical patent/WO2022106833A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02416—Detecting, measuring or recording pulse rate or heart rate using photoplethysmograph signals, e.g. generated by infrared radiation
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/02438—Detecting, measuring or recording pulse rate or heart rate with portable devices, e.g. worn by the patient
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/024—Detecting, measuring or recording pulse rate or heart rate
    • A61B5/0245—Detecting, measuring or recording pulse rate or heart rate by using sensing means generating electric signals, i.e. ECG signals
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
    • A61B5/0535—Impedance plethysmography
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A61B5/1118—Determining activity level
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/318—Heart-related electrical modalities, e.g. electrocardiography [ECG]
    • A61B5/346—Analysis of electrocardiograms
    • A61B5/349—Detecting specific parameters of the electrocardiograph cycle
    • A61B5/352—Detecting R peaks, e.g. for synchronising diagnostic apparatus; Estimating R-R interval
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6802—Sensor mounted on worn items
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
    • A61B5/6802—Sensor mounted on worn items
    • A61B5/6804—Garments; Clothes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7203—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal
    • A61B5/7207—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts
    • A61B5/721—Signal processing specially adapted for physiological signals or for diagnostic purposes for noise prevention, reduction or removal of noise induced by motion artifacts using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7221—Determining signal validity, reliability or quality

Definitions

  • the present invention is directed towards a method and system for detecting peaks in a biosignal such as a signal indicative of the heartrate or a bioimpedance signal.
  • the peaks may be R- peaks in a signal indicative of a heartrate such as an electrocardiogram signal.
  • the present invention is directed towards methods and systems for improving the process for removing spurious detected peaks.
  • Wearable articles such as garments, incorporating sensors are wearable electronics used to measure and collect information from a wearer.
  • wearable articles are commonly referred to as ‘smart clothing’. It is advantageous to measure biosignals of the wearer during exercise, or other scenarios.
  • an electronic device i.e. an electronics module, and/or related components
  • the electronic device is a detachable device.
  • the electronic device is configured to process the incoming signals, and the output from the processing is stored and/or displayed to a user in a suitable way
  • a sensor senses a biosignal such as electrocardiogram (ECG) signals and the biosignals are coupled to the electronic device, via an interface.
  • ECG electrocardiogram
  • the sensors may be coupled to the interface by means of conductors which are connected to terminals provided on the interface to enable coupling of the signals from the sensor to the interface.
  • Electronics modules for wearable articles such as garments are known to communicate with user electronic devices over wireless communication protocols such as Bluetooth ® and Bluetooth ® Low Energy. These electronics modules are typically removably attached to the wearable article, interface with internal electronics of the wearable article, and comprise a Bluetooth ® antenna for communicating with the user electronic device.
  • the electronic device includes drive and sensing electronics comprising components and associated circuitry, to provide the required functionality.
  • the drive and sensing electronics include a power source to power the electronic device and the associated components of the drive and sensing circuitry.
  • ECG sensing is used to provide a plethora of information about a person’s heart. It is one of the simplest and oldest techniques used to perform cardiac investigations. In its most basic form, it provides an insight into the electrical activity generated within heart muscles that changes over time. By detecting and amplifying these differential biopotential signals, a lot of information can be gathered quickly, including the heart rate.
  • individual signals have names such as “the QRS complex,” which is the largest part of an ECG signal and is a collection of Q, R, and S signals, including the P and T waves.
  • lay persons Whilst lay persons may not be aware of the clinical aspects and significance of an ECG signal trace, lay persons would usually recognise the general form of such a signal trace, if only as a measure of heart rate.
  • the detected ECG signals can be displayed as a trace to a user for information.
  • the user may be a clinician who is looking to assess cardiac health or may be a lay user using the electronics module as a fitness or health and wellness assessment device.
  • a typical ECG waveform or trace is illustrated in Figure 1 showing the QRS complex.
  • Figure 2 shows an ECG waveform of two successive heartbeats.
  • the time difference between the two R-peaks in the ECG waveform is the inter-beat interval (I Bl) also known as the R-R interval.
  • IBI values can also be calculated based on the difference between other peaks such as between two successive S peaks. This time is usually expressed in milliseconds. IBI values represent the time between successive heartbeats.
  • Peak detection algorithms are known in the art.
  • Example peak algorithms include the Pan Tomkins algorithm as described in Pan, Jiapu; Tompkins, Willis J. (March 1985). "A Real-Time QRS Detection Algorithm". IEEE Transactions on Biomedical Engineering. BME-32 (3): 230-236.
  • peak detection algorithms involve comparing candidate peaks against a threshold level. Candidate peaks that are below the threshold level are used to calculate the IBI values.
  • US Patent No. 8,032,206 B1 discloses a method of detecting a heart rate of a patient.
  • the method comprises: sensing via a first sensor a first signal indicative of heartrate; sensing via a second sensor a second signal indicative of motion of the patient’s chest due to respiration; adjusting a threshold value of the amplitude of the first signal based on the second signal; and determining the heart rate as a function of the adjusted threshold value and the first signal.
  • the threshold value is increased in response to a determination of inflation of a patient’s chest due to respiration.
  • the threshold value is decreased in response to a determination of deflation of the patient’s chest due to respiration.
  • the threshold value is kept constant in response to a determination of no substantial movement of the patient’s chest.
  • An object of the present invention is to provide an improved process for detecting peaks from a biosignal.
  • the signal may be a signal indicative of the heartrate such as an ECG signal.
  • a method of detecting peaks in a biological signal for a subject comprises obtaining subject specific information indicative of the signal-to-noise ratio of the signal.
  • the method comprises obtaining signal values for the signal.
  • the method comprises filtering the signal values.
  • the method comprises detecting one or more candidate peaks in the filtered signal values.
  • the method comprises determining if a detected candidate peak has an amplitude less than a threshold level, and if the detected candidate peak has an amplitude less than the threshold level, removing the detected candidate peak.
  • the threshold level is determined at least in part according to the subject specific information. In other words, the method comprises removing one or more detected candidate peaks that have an amplitude less than a threshold level.
  • the biological signal is also referred to as a biosignal.
  • the signal may be a signal indicative of a heartrate for the subject.
  • the threshold level is determined at least in part according to subject specific information that is indicative of the signal-to-noise level of the signal (e.g. an ECG signal or a bioimpedance signal such as an impedance plethysmography signal).
  • subject specific information that is indicative of the signal-to-noise level of the signal
  • the threshold level is therefore adaptable based on the subject specific information.
  • the threshold level can change for different subjects or for different circumstances surrounding a certain subject.
  • the threshold level being adaptable based on subject-specific information can improve the removal of spurious peaks and can reduce the likelihood of a true peak being accidentally removed.
  • the previous approach described in US8,032,206 B1 only adjusts the threshold based on whether the subject is breathing in or out and does not consider the signal-to-noise ration of the signal.
  • the existing approach is unable to dynamically compensate changes in noise level in the signal.
  • the subject specific information may be obtained from a source other than the biological signal.
  • the signal indicative of the heartrate may be an ECG signal but this is not required in all examples and other signals indicative of the heartrate are within the scope of the present disclosure.
  • Other signals indicative of the heartrate include photoplethysmography (PPG) signals, ballistocardiogram (BCG) signals, and electromagnetic cardiogram (EMCG) signals.
  • PPG photoplethysmography
  • BCG ballistocardiogram
  • EMCG electromagnetic cardiogram
  • the signal may be a bioimpedance signal such as an impedance plethysmography signal.
  • Impedance plethysmography signals may be used to monitor the respiration of the subject.
  • the subject specific information may indicate that the signal-to-noise ratio of the signal has changed.
  • the method may comprise adjusting the threshold level based on the change in the signal-to-noise ratio.
  • the method may further comprise increasing the threshold level when the subject specific information indicates that the signal-to-noise ratio has increased.
  • the method may further comprise decreasing the threshold level when the subject specific information indicates that the signal-to-noise ratio has decreased.
  • the threshold level may be determined according to the product of an adjustable threshold value and a measure of the power of the filtered signal values.
  • the method may comprise adjusting the threshold value according to the subject specific information.
  • the subject specific information may comprise activity data for the subject.
  • the activity data may indicate an activity level for the subject.
  • the activity data may indicate that an activity level for the subject has changed.
  • the change in the activity level is indicative of a change in the signal-to-noise ratio of the signal.
  • the method may further comprise adjusting the threshold level based on the change in activity level.
  • the activity data may be indicative of an increase in the signal-to-noise ratio of the signal.
  • the method may further comprise increasing the threshold level according to the increase in the signal-to-noise ratio.
  • the activity data may be indicative of a decrease in the signal-to-noise ratio of the signal.
  • the method may further comprise decreasing the threshold level according to the decrease in the signal-to-noise ratio.
  • the subject specific information may comprise information indicating a characteristic of the subject.
  • the characteristic of the subject may comprise one or more of the age, weight, height, body fat percentage, gender, ethnicity, fitness level, diet, medical history, or lifestyle of the subject.
  • the method may further comprise adjusting the threshold level based on the characteristic of the subject.
  • the method may further comprise calculating one or more IBI values from the remaining peaks having an amplitude greater than the threshold level.
  • the method may be for detecting R-peaks in an ECG signal.
  • the IBI values may be R-R interval values.
  • the peaks are not required to be R-peaks.
  • the method may be for detecting other characteristic peaks of an ECG signal such as S-peaks or other characteristic peaks in signals indicative of the heartrate of the subject.
  • a computer readable medium having instructions recorded thereon which, when executed by a processor, cause the processor to perform the method according to the first aspect of the disclosure.
  • an electronics module for a wearable article.
  • the electronics module comprises an interface arranged to couple with sensing components such as electrodes to record biological signals for a subject.
  • the electronics module comprises a controller.
  • the controller is operable to obtain subject specific information indicative of the signal-to-noise ratio of the signal.
  • the controller is operable to receive signal values for the signal from the interface.
  • the controller is operable to filter the signal values.
  • the controller is operable to detect one or more candidate peaks in the filtered signal values.
  • the controller is operable to determine if a detected candidate peak has an amplitude less than a threshold level, and if the detected candidate peak has an amplitude less than the threshold level, remove the detected candidate peak.
  • the threshold level is determined at least in part according to the subject specific information. In other words, the controller is operable to remove one or more detected peaks that have an amplitude less than a threshold level.
  • the subject specific information may comprise information indicating a characteristic of the subject.
  • the controller may be operable to receive the information indicating a characteristic of the subject from an external device such as a user electronic device.
  • the subject specific information may comprise activity data for the subject.
  • the electronics module may comprise a motion sensor arranged to detect a change in the activity level for the subject and provide, to the controller, activity data for the subject indicative of the change in activity level.
  • the electronics module may be operable to adjust the threshold level based on the change in activity level.
  • a method of detecting peaks in a biological signal comprises obtaining subject specific information indicative of the signal-to-noise ratio of the signal.
  • the method comprises obtaining signal values forthe subject.
  • the method comprises adjusting a threshold level using the subject specific information.
  • the method further comprises detecting one or more peaks in the signal values using the adjusted threshold level.
  • the method may comprise any of the features of the first aspect of the disclosure.
  • Figure 1 illustrates a signal trace for an ECG signal
  • FIG. 2 illustrates an ECG waveform that includes electrical signals for two successive heartbeats
  • Figure 3 shows a schematic diagram for an example system according to aspects of the present disclosure
  • Figure 4 shows a schematic diagram for an example electronics module according to aspects of the present disclosure
  • Figure 5 shows a schematic diagram for another example electronics module according to aspects of the present disclosure
  • Figure 6 shows a schematic diagram for an example analogue-to-digital converter used in the example electronics module of Figures 4 and 5 according to aspects of the present disclosure
  • Figure 7 shows a flow diagram for an example method of detecting R-peaks according to aspects of the present disclosure
  • Figure 8 shows an ECG waveform for a subject when standing
  • Figure 9 shows an ECG waveform for a subject when jogging
  • Figure 10 shows an ECG waveform for a subject when running
  • Figure 11 shows a flow diagram for another example method of detecting R-peaks according to aspects of the present disclosure.
  • “Wearable article” as referred to throughout the present disclosure may refer to any form of device interface which may be worn by a user such as a smart watch, necklace, garment, bracelet, or glasses.
  • the wearable article may be a textile article.
  • the wearable article may be a garment.
  • the garment may refer to an item of clothing or apparel.
  • the garment may be a top.
  • the top may be a shirt, t-shirt, blouse, sweater, jacket/coat, or vest.
  • the garment may be a dress, garment brassiere, shorts, pants, arm or leg sleeve, vest, jacket/coat, glove, armband, underwear, headband, hat/cap, collar, wristband, stocking, sock, or shoe, athletic clothing, personal protective equipment, including hard hats, swimwear, wetsuit or dry suit.
  • the term “wearer” includes a user who is wearing, or otherwise holding, the wearable article.
  • the type of wearable garment may dictate the type of biosignals to be detected.
  • a hat or cap may be used to detect electroencephalogram or magnetoencephalogram signals.
  • the wearable article/garment may be constructed from a woven or a non-woven material.
  • the wearable article/garment may be constructed from natural fibres, synthetic fibres, or a natural fibre blended with one or more other materials which can be natural or synthetic.
  • the yarn may be cotton.
  • the cotton may be blended with polyester and/or viscose and/or polyamide according to the application.
  • Silk may also be used as the natural fibre.
  • Cellulose, wool, hemp and jute are also natural fibres that may be used in the wearable article/garment.
  • Polyester, polycotton, nylon and viscose are synthetic fibres that may be used in the wearable article/garment.
  • the garment may be a tight-fitting garment.
  • a tight-fitting garment helps ensure that the sensor devices of the garment are held in contact with or in the proximity of a skin surface of the wearer.
  • the garment may be a compression garment.
  • the garment may be an athletic garment such as an elastomeric athletic garment.
  • the garment has sensing units provided on an inside surface which are held in close proximity to a skin surface of a wearer wearing the garment. This enables the sensing units to measure biosignals for the wearer wearing the garment.
  • the sensing units may be arranged to measure one or more biosignals of a wearer wearing the garment.
  • Biosignal “Biological Signals” as referred to throughout the present disclosure may refer to signals from living beings that can be continually measured or monitored. Biosignals may be electrical or non-electrical signals. Signal variations can be time variant or spatially variant.
  • Sensing components may be used for measuring one or a combination of bioelectrical, bioimpedance, biochemical, biomechanical, bioacoustics, biooptical or biothermal signals of the wearer 600.
  • the bioelectrical measurements include electrocardiograms (ECG), electrogastrograms (EGG), electroencephalograms (EEG), and electromyography (EMG).
  • the bioimpedance measurements include plethysmography (e.g., for respiration), body composition (e.g., hydration, fat, etc.), and electroimpedance tomography (EIT).
  • the biomagnetic measurements include magneto neurograms (MNG), magnetoencephalography (MEG), magnetogastrogram (MGG), magnetocardiogram (MCG).
  • the biochemical measurements include glucose/lactose measurements which may be performed using chemical analysis of the wearer 600’s sweat.
  • the biomechanical measurements include blood pressure.
  • the bioacoustics measurements include phonocardiograms (PCG).
  • the biooptical measurements include orthopantomogram (OPG).
  • the biothermal measurements include skin temperature and core body temperature measurements.
  • the system 10 comprises an electronics module 100, a wearable article in the form of a garment 200, and a user electronic device 300.
  • the garment 200 is worn by a user who in this embodiment is the wearer 600 of the garment 200.
  • the electronics module 100 is arranged to integrate with sensing units 400 incorporated into the garment 200 to obtain signals from the sensing units 400.
  • the electronics module 100 and the wearable article 200 and including the sensing units 400 comprise a wearable assembly 500.
  • the sensing units 400 comprise one or more sensors 209, 21 1 with associated conductors 203, 207 and other components and circuitry.
  • the electronics module 100 is further arranged to wirelessly communicate data to the user electronic device 300.
  • Various protocols enable wireless communication between the electronics module 100 and the user electronic device 300.
  • Example communication protocols include Bluetooth ®, Bluetooth ® Low Energy, and near-field communication (NFC).
  • the garment 200 has an electronics module holder in the form of a pocket 201 .
  • the pocket 201 is sized to receive the electronics module 100.
  • the electronics module 100 is arranged to receive sensor data from the sensing units 400.
  • the electronics module 100 is therefore removable from the garment 200.
  • the present disclosure is not limited to electronics module holders in the form pockets.
  • the electronics module 100 may be configured to be releasably mechanically coupled to the garment 200.
  • the mechanical coupling of the electronic module 100 to the garment 200 may be provided by a mechanical interface such as a clip, a plug and socket arrangement, etc.
  • the mechanical coupling or mechanical interface may be configured to maintain the electronic module 100 in a particular orientation with respect to the garment 200 when the electronic module 100 is coupled to the garment 200. This may be beneficial in ensuring that the electronic module 100 is securely held in place with respect to the garment 200 and/or that any electronic coupling of the electronic module 100 and the garment 200 (or a component of the garment 200) can be optimized.
  • the mechanical coupling may be maintained using friction or using a positively engaging mechanism, for example.
  • the removable electronic module 100 may contain all the components required for data transmission and processing such that the garment 200 only comprises the sensing units 400 e.g. the sensors 209, 211 and communication pathways 203, 207.
  • the sensors 209, 21 1 may be electrodes.
  • manufacture of the garment 200 may be simplified.
  • it may be easier to clean a garment 200 which has fewer electronic components attached thereto or incorporated therein.
  • the removable electronic module 100 may be easier to maintain and/or troubleshoot than embedded electronics.
  • the electronic module 100 may comprise flexible electronics such as a flexible printed circuit (FPC).
  • FPC flexible printed circuit
  • the electronic module 100 may be configured to be electrically coupled to the garment 200.
  • FIG 4 there is shown a schematic diagram of an example of the electronics module 100 of Figure 1.
  • FIG 5 A more detailed block diagram of the electronics components of electronics module 100 and garment are shown in Figure 5.
  • the electronics module 100 comprises an interface 101 , a controller 103, a power source 105, and one or more communication devices which, in the exemplar embodiment comprises a first antenna 107, a second antenna 109 and a wireless communicator 159.
  • the electronics module 100 also includes an input unit such as a proximity sensor or a motion sensor 111 , for example in the form of an inertial measurement unit (IMU).
  • IMU inertial measurement unit
  • the electronics module 100 also includes additional peripheral devices that are used to perform specific functions as will be described in further detail herein.
  • the interface 101 is arranged to communicatively couple with the sensing unit 400 of the garment 200.
  • the sensing unit 400 comprises - in this example - the two sensors 209, 211 coupled to respective first and second electrically conductive pathways 203, 207, each with respective termination points 213, 215.
  • the interface 101 receives signals from the sensors 209, 211.
  • the controller 103 is communicatively coupled to the interface 101 and is arranged to receive the signals from the interface 101 for further processing.
  • the interface 101 of the embodiment described herein comprises first and second contacts 163, 165 which are arranged to be communicatively coupled to the termination points 213, 215 the respective first and second electrically conductive pathways 203, 207.
  • the coupling between the termination points 213, 215 and the respective first and second contacts 163, 165 may be conductive or a wireless (e.g. inductive) communication coupling.
  • the sensors 209, 211 are used to measure electropotential signals such as electrocardiogram (ECG) signals, although the sensors 209, 211 could be configured to measure other biosignal types as also discussed above.
  • ECG electrocardiogram
  • the sensors 209, 211 are configured for so-called dry connection to the wearer’s skin to measure ECG signals.
  • the power source 105 may comprise a plurality of power sources.
  • the power source 105 may be a battery.
  • the battery may be a rechargeable battery.
  • the battery may be a rechargeable battery adapted to be charged wirelessly such as by inductive charging.
  • the power source 105 may comprise an energy harvesting device.
  • the energy harvesting device may be configured to generate electric power signals in response to kinetic events such as kinetic events performed by the wearer 600 of the garment 200.
  • the kinetic event could include walking, running, exercising or respiration of the wearer 600.
  • the energy harvesting material may comprise a piezoelectric material which generates electricity in response to mechanical deformation of the converter.
  • the energy harvesting device may harvest energy from body heat of the wearer 600 of the garment.
  • the energy harvesting device may be a thermoelectric energy harvesting device.
  • the power source 105 may be a super capacitor, or an energy cell.
  • the first antenna 107 is arranged to communicatively couple with the user electronic device 300 using a first communication protocol.
  • the first antenna 107 is a passive tag such as a passive Radio Frequency Identification (RFID) tag or Near Field Communication (NFC) tag.
  • RFID Radio Frequency Identification
  • NFC Near Field Communication
  • These tags comprise a communication module as well as a memory which stores the information, and a radio chip.
  • the user electronic device 300 is powered to induce a magnetic field in an antenna of the user electronic device 300.
  • the user electronic device 300 When the user electronic device 300 is placed in the magnetic field of the communication module antenna 107, the user electronic device 300 induces current in the communication module antenna 107. This induced current triggers the electronics module 100 to retrieve the information from the memory of the tag and transmit the same back to the user electronic device 300.
  • the user electronic device 300 is brought into proximity with the electronics module 100.
  • the electronics module 100 is configured to energize the first antenna 107 to transmit information to the user electronic device 300 over the first wireless communication protocol.
  • the information may comprise a unique identifier for the electronics module 100.
  • the unique identifier for the electronics module 100 may be an address for the electronics module 100 such as a MAC address or Bluetooth ® address.
  • the information may comprise authentication information used to facilitate the pairing between the electronics module 100 and the user electronic device 300 over the second wireless communication protocol. This means that the transmitted information is used as part of an out of band (OOB) pairing process.
  • OOB out of band
  • the information may comprise application information which may be used by the user electronic device 300 to start an application on the user electronic device 300 or configure an application running on the user electronic device 300.
  • the application may be started on the user electronic device 300 automatically (e.g. without wearer 600 input).
  • the application information may cause the user electronic device 300 to prompt the wearer 600 to start the application on the user electronic device.
  • the information may comprise a uniform resource identifier such as a uniform resource location to be accessed by the user electronic device, or text to be displayed on the user electronic device for example. It will be appreciated that the same electronics module 100 can transmit any of the above example information either alone or in combination.
  • the electronics module 100 may transmit different types of information depending on the current operational state of the electronics module 100 and based on information it receives from other devices such as the user electronic device 300.
  • the second antenna 109 is arranged to communicatively couple with the user electronic device 300 over a second wireless communication protocol.
  • the second wireless communication protocol may be a Bluetooth ® protocol, Bluetooth ® 5 or a Bluetooth ® Low Energy protocol but is not limited to any particular communication protocol.
  • the second antenna 109 is integrated into controller 103.
  • the second antenna 109 enables communication between the user electronic device 300 and the controller 100 for configuration and set up of the controller 103 and the peripheral devices as may be required. Configuration of the controller 103 and peripheral devices utilises the Bluetooth ® protocol.
  • the wireless communicator 159 may be an alternative, or in addition to, the first and second antennas 107, 109.
  • Other wireless communication protocols can also be used, such as used for communication over: a wireless wide area network (WWAN), a wireless metro area network (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN), Bluetooth ® Low Energy, Bluetooth ® Mesh, Thread, Zigbee, IEEE 802.15.4, Ant, a Global Navigation Satellite System (GNSS), a cellular communication network, or any other electromagnetic RF communication protocol.
  • WWAN wireless wide area network
  • WMAN wireless metro area network
  • WLAN wireless local area network
  • WPAN wireless personal area network
  • Bluetooth ® Low Energy Bluetooth ® Mesh, Thread, Zigbee, IEEE 802.15.4, Ant, a Global Navigation Satellite System (GNSS), a cellular communication network, or any other electromagnetic RF communication protocol.
  • GNSS Global Navigation Satellite System
  • the cellular communication network may be a fourth generation (4G) LTE, LTE Advanced (LTE-A), LTE Cat-M1 , LTE Cat-M2, NB-loT, fifth generation (5G), sixth generation (6G), and/or any other present or future developed cellular wireless network.
  • 4G fourth generation
  • LTE-A LTE Advanced
  • LTE Cat-M1 LTE Cat-M2
  • NB-loT fifth generation
  • 5G fifth generation
  • 6G sixth generation
  • any other present or future developed cellular wireless network may be any other present or future developed cellular wireless network.
  • the electronics module 100 includes configured a clock unit in the form of a real time clock (RTC) 153 coupled to the controller 103 and, for example, to be used for data logging, clock building, time stamping, timers, and alarms.
  • RTC real time clock
  • the RTC 153 is driven by a low frequency clock source or crystal operated at 32.768 Hz.
  • the electronics module 100 also includes a location device 161 such as a GNSS (Global Navigation Satellite System) device which is arranged to provide location and position data for applications as required.
  • a location device 161 such as a GNSS (Global Navigation Satellite System) device which is arranged to provide location and position data for applications as required.
  • the location device 161 provides geographical location data at least to a nation state level. Any device suitable for providing location, navigation or for tracking the position could be utilised.
  • the GNSS device may include device may include Global Positioning System (GPS), BeiDou Navigation Satellite System (BDS) and the Galileo system devices.
  • the power source 105 in this example is a lithium polymer battery 105.
  • the battery 105 is rechargeable and charged via a USB C input 131 of the electronics module 100.
  • the present disclosure is not limited to recharging via USB and instead other forms of charging such as inductive of far field wireless charging are within the scope of the present disclosure.
  • Additional battery management functionality is provided in terms of a charge controller 133, battery monitor 135 and regulator 147. These components may be provided through use of a 30 dedicated power management integrated circuit (PMIC).
  • PMIC power management integrated circuit
  • the USB C input 131 is also coupled to the controller 131 to enable direct communication with the controller 103 with an external device if required.
  • the controller 103 is communicatively connected to a battery monitor 135 so that that the controller 103 may obtain information about the state of charge of the battery 105.
  • the controller 103 has an internal memory 167 and is also communicatively connected to an external memory 143 which in this example is a NAND Flash memory.
  • the memory 143 is used to for the storage of data when no wireless connection is available between the electronics module 100 and a user electronic device 300.
  • the memory 143 may have a storage capacity of at least 1 GB and preferably at least 2 GB.
  • the electronics module 100 also comprises a temperature sensor 145 and a light emitting diode 147 for conveying status information.
  • the electronic module 100 also comprises conventional electronics components including a power-on-reset generator 149, a development connector 151 , the real time clock 153 and a PROG header 155.
  • the electronics module 100 may comprise a haptic feedback unit 157 for providing a haptic (vibrational) feedback to the wearer 600.
  • the wireless communicator 159 may provide wireless communication capabilities for the garment 200 and enables the garment to communicate via one or more wireless communication protocols to a remote server 700.
  • Wireless communications may include : a wireless wide area network (WWAN), a wireless metro area network (WMAN), a wireless local area network (WLAN), a wireless personal area network (WPAN), Bluetooth ® Low Energy, Bluetooth ® Mesh, Bluetooth ® 5, Thread, Zigbee, IEEE 802.15.4, Ant, a near field communication (NFC), a Global Navigation Satellite System (GNSS), a cellular communication network, or any other electromagnetic RF communication protocol.
  • WWAN wireless wide area network
  • WMAN wireless metro area network
  • WLAN wireless local area network
  • WPAN wireless personal area network
  • Bluetooth ® Low Energy Bluetooth ® Mesh
  • Bluetooth ® 5 Thread
  • Zigbee IEEE 802.15.4
  • Ant Ant
  • NFC near field communication
  • GNSS Global Navigation Satellite System
  • cellular communication network or any other electromagnetic RF communication protocol.
  • the cellular communication network may be a fourth generation (4G) LTE, LTE Advanced (LTE-A), LTE Cat-M1 , LTE Cat-M2, NB-loT, fifth generation (5G), sixth generation (6G), and/or any other present or future developed cellular wireless network.
  • 4G fourth generation
  • LTE-A LTE Advanced
  • LTE Cat-M1 LTE Cat-M2
  • NB-loT fifth generation
  • 5G fifth generation
  • 6G sixth generation
  • any other present or future developed cellular wireless network may be any other present or future developed cellular wireless network.
  • the electronics module 100 may additionally comprise a Universal Integrated Circuit Card (UICC) that enables the garment to access services provided by a mobile network operator (MNO) or virtual mobile network operator (VMNO).
  • the UICC may include at least a read-only memory (ROM) configured to store an MNO or VMNO profile that the garment can utilize to register and interact with an MNO or VMNO.
  • the UICC may be in the form of a Subscriber Identity Module (SIM) card.
  • SIM Subscriber Identity Module
  • the electronics module 100 may have a receiving section arranged to receive the SIM card.
  • the UICC is embedded directly into a controller of the electronics module 100. That is, the UICC may be an electronic/embedded UICC (eUlCC).
  • a eUlCC is beneficial as it removes the need to store a number of MNO profiles, i.e. electronic Subscriber Identity Modules (eSIMs). Moreover, eSIMs can be remotely provisioned to garments.
  • the electronics module 100 may comprise a secure element that represents an 35 embedded Universal Integrated Circuit Card (eUlCC). In the present disclosure, the electronics module may also be referred to as an electronics device or unit. These terms may be used interchangeably.
  • the controller 103 is connected to the interface 101 via an analog-to-digital converter (ADC) front end 139 and an electrostatic discharge (ESD) protection circuit 141.
  • ADC analog-to-digital converter
  • ESD electrostatic discharge
  • FIG. 6 is a schematic illustration of the component circuitry for the ADC front end 139.
  • the ADC front end 139 forms part of the interface that couples the garment sensors 209, 21 1 (e.g. electrodes 209, 211) to the controller 103.
  • the ADC front end 139 is an integrated circuit (IC) chip which converts the raw analogue biosignal received from the sensors 209, 211 into a digital signal for further processing by the controller 103.
  • IC integrated circuit
  • ADC IC chips are known, and any suitable one can be utilised to provide this functionality.
  • ADC IC chips for ECG applications include, for example, the MAX30003 chip produced by Maxim Integrated Products Inc.
  • the ADC front end 139 includes an input 169 and an output 171.
  • Raw biosignals from the electrodes 209, 211 are input to the ADC front end 139, where received signals are processed in an ECG channel 175 and subject to appropriate filtering such as notch filters, high pass and low pass filters for mains noise, static discharge and interference reduction as well as for reducing bandwidth prior to conversion to digital signals.
  • filtering such as notch filters, high pass and low pass filters for mains noise, static discharge and interference reduction as well as for reducing bandwidth prior to conversion to digital signals.
  • the reduction in bandwidth is important to remove or reduce motion artefacts that give rise to noise in the signal due to movement of the sensors 209, 211 and the effect of impact forces on the electrical components.
  • the output digital signals may be decimated to reduce the sampling rate prior to being passed to a serial programmable interface (SPI) 173 of the ADC front end 139. Signals are output to the controller 103 via the SPI 173.
  • SPI serial programmable interface
  • the digital signal values output to the controller 103 are stored in a FIFO data buffer.
  • the controller 103 performs operations to detect R-peaks from the digital signal values. The operations are performed in real-time while the ADC front end 139 are outputting new digital signals to the controller 103.
  • Figure 7 provides a flow diagram for an example method performed by the controller 103 for identifying R-peaks in the ECG signal using the ECG digital signal values forthe subject obtained from the ADC front end 139.
  • the R-peaks are used to calculate R-R interval values.
  • step S101 the controller 103 obtains subject specific information indicative of the signal-to- noise ratio of the ECG signal.
  • the controller 102 obtains the ECG signal values from the ADC front end 139.
  • the subject specific information is different to the ECG signal values.
  • the subject specific information provides further context to the ECG signal values and is used to adapt the thresholding process used to remove spurious R-peaks.
  • the subject specific information may comprise information relating to the activity of the subject and/or a characteristic of the subject.
  • step S103 the controller 103 filters the ECG signal values.
  • Many different filtering operations can be used to aid in the detection of R-peaks.
  • Example filters include notch filters, low pass filters, high pass filters, and bandpass filters.
  • step S104 the controller 103 detects one or more candidate R-peaks in the filtered ECG signal values.
  • Many peak detection approaches may be used. These peak detection approaches typically involve detecting local maxima in the ECG signal values.
  • step S105 the controller 103 removes detected candidate R-peaks that have an amplitude less than a threshold level.
  • the controller 103 does this by determining if a detected candidate peak has an amplitude less than a threshold level, and if the detected candidate peak has an amplitude less than the threshold level, removing the detected candidate peak.
  • the threshold level is determined at least in part according to the subject specific information.
  • this means that the threshold level is set based on subject specific information indicative of the signal-to-noise ratio of the ECG signal. This improves the accuracy of the R-peak detection method as it is adaptable based on particular properties of the subject.
  • the subject specific information is indicative of a signal-to-noise ratio for the ECG signal. If the subject is likely to have a high signal-to-noise ratio for their ECG signal then a high threshold level can be selected because the true R-peaks in the ECG signal are likely to have a far higher amplitude than spurious peaks caused by noise, for example. If the subject is likely to have a low signal-to-noise ratio then a low threshold level can be selected because the true R-peaks in the signal are likely to have a lower amplitude and may be missed if the threshold level is too high.
  • the present disclosure advantageously configures the threshold level according to the likely signal-to-noise ratio for the ECG signal as identified by the subject specific information.
  • the signal-to-noise ratio is not calculated directly from the ECG signal. Instead, the subject specific information provides information relating to one or more properties of the subject that indicate a likely signal-to-noise ratio. This is computationally more efficient than calculating the signal-to-noise ratio directly and allows for real time R-peak detection and removal even at a high sampling rate such as 512 Hz.
  • the subject specific information for the subject comprises activity data for the subject such as an activity level of the subject. If the user has a high activity level (such as when they are running), the signal-to-noise ratio for the ECG signal is likely to be lower due to the introduction of greater motion artefacts.
  • the controller 103 By adjusting the threshold level to compensate for the decreased signal-to-noise ratio, the controller 103 is able to reduce the number of missed true R-peaks. Meanwhile, if the user has a low activity level (such as when they are sitting or standing), the signal-to-noise ratio for the ECG signal is likely to be higher. By adjusting the threshold level to compensate for the increased signal-to-noise ratio, the controller 103 is able to remove a greater number of spurious peaks.
  • the subject specific information for the subject comprises information indicating a characteristic of the subject. Different characteristics of the user can be indicative of different signal-to-noise ratios that will be expected in the ECG signal. Factors such as gender, weight, and body fat level are indicative of different signal-to-noise ratios in the ECG signals for the subject.
  • the controller 103 is able to adapt the threshold based on the particular characteristics of the subject to provide subject-specific R-peak detection.
  • the R-peaks remaining after step S105 are used to calculate one or more R-R intervals for the subject. Only one R-R interval may be determined if only one R-peak remains after step S105. In this case, the R-R interval will be determined using the timestamp of the last R-peak found in the previous window of data.
  • One or more additional steps may be performed prior to calculating the R-R intervals such as to further check the remaining peaks after step S105 and remove or compensate for any remaining spurious peaks.
  • the number and extent of the spurious remaining speaks is at least reduced due to the subject specific information being used in setting the threshold level.
  • These spurious peaks may be due to noise spikes, ectopic beats or other ECG components.
  • An example process for detecting spurious peaks is disclosed in Mateo J, Website. Analysis of heart rate variability in the presence of ectopic beats using the heart timing signal. IEEE Trans Biomed Eng. 2003 Mar;50(3):334-43.
  • Steps S104 and S105 may only be performed when at least N filtered ECG signal values are obtained.
  • N is a number that may be selected by the skilled person as desired to ensure that there are likely to be a certain desired number of peaks within the window of filtered signal values.
  • N may be selected such that filtered ECG signal values corresponding to at least 4 seconds of data are obtained to ensure that there are at least 2 peaks in any window.
  • step S101 If less than N samples of filtered signal values have been obtained then method returns to step S101 so that additional samples are gathered and filtered. Steps S101 and S102 may be repeated until the N signal values are obtained. If N or more samples of the filtered signal values have been obtained, then steps S104 and S105 are performed.
  • motion detection is provided by the IMU 111 which may comprise an accelerometer and optionally one or both of a gyroscope and a magnetometer.
  • a gyroscope/magnetometer is not required in all examples, and instead only an accelerometer may be provided, or a gyroscope/magnetometer may be present but put into a low power state.
  • IMUs that can be used for this application include the ST LSM6DSOX manufactured by STMicroelectronics. This IMU a system-in-package IMU featuring a 3D digital accelerometer and a 3D digital gyroscope.
  • LSM6DSO Another example of a known IMU suitable for this application is the LSM6DSO also be STMicroelectronics.
  • the IMU 111 can include machine learning functionality, for example as provided in the ST LSM6DSOX.
  • the machine learning functionality is implemented in a machine learning core (MLC).
  • MLC machine learning core
  • the machine earning processing capability uses decision-tree logic.
  • the MLC is an embedded feature of the IMU 111 and comprises a set of configurable parameters and decision trees.
  • decision tree is a mathematical tool composed of a series of configurable nodes. Each node is characterized by an “if-then-else” condition, where an input signal (represented by statistical parameters calculated from the sensor data) is evaluated against a threshold.
  • Decision trees are stored and generate results in the dedicated output registers.
  • the results of the decision tree can be read from the application processor at any time. Furthermore, there is the possibility to generate an interrupt for every change in the result in the decision tree, which is beneficial in maintaining low-power consumption.
  • Decision trees can be generated using known machine learning tool such as Weka developed by the University of Waikato or using MATLAB or Python.
  • a processor of the IMU 11 1 may perform processing tasks to classify different types of detected motion.
  • the processor of the IMU 111 may use the machine-learning functions so as to perform this classification.
  • Performing the processing operations on the IMU 1 11 rather than the controller 103 is beneficial as it reduces power consumption and leaves the controller 103 free to perform other tasks. In addition, it allows for motion events to be detected even when the controller 103 is operating in a low power mode.
  • the IMU 111 communicates with the controller 103 over a serial protocol such as the Serial Peripheral Interface (SPI), Inter- Integrated Circuit (I2C), Controller Area Network (CAN), and Recommended Standard 232 (RS-232).
  • SPI Serial Peripheral Interface
  • I2C Inter- Integrated Circuit
  • CAN Controller Area Network
  • RS-232 Recommended Standard 232
  • Other serial protocols are within the scope of the present disclosure.
  • the IMU 1 11 outputs activity data to the controller 103 when the IMU 111 detects that the activity level of the subject has changed. This may occur when the subject switches from a first activity associated with a high signal-to-noise ratio to a second activity associated with a lower signal- to-noise ratio or vice versa. For example, the IMU 111 may detect that the user switches from sitting to standing or walking to running. Other activities may be detected by the IMU 11 1 such as jumping, cycling or swimming.
  • FIG. 8 shows a plot of an ECG signal trace for a subject when standing.
  • the ECG signal has a high signal-to-noise ratio with clearly defined R-peaks and limited noise between the R-peaks.
  • the IMU 111 detects that the user has the first activity level (standing) and outputs a signal representative of the first activity level to the controller 103.
  • the IMU 111 of the electronics module 100 can be configured to use decision tree logic to determine the activity level of the subject wearing the electronics module 100 and to provide an output to the controller 103.
  • the IMU 111 may output a value of “1 ” to the controller 103.
  • the IMU 111 is not required to perform the activity classification in all examples.
  • the controller 103 may, for example, determine an activity level of the subject from activity data received from the IMU 1 11. This may be performed using machine-learning logic implemented by the controller 103.
  • the controller 103 identifies from the received signal that the user has an activity level associated with a high signal-to-noise ratio for the ECG signal.
  • the controller 103 adjusts the threshold level based on the received signal so as to optimise the peak removal process for the signal-to-noise ratio of the ECG signal. Subsequent iterations of steps S101 to S105 use the adjusted threshold level.
  • the adjusted threshold level is used until another signal is received by the controller 103 from the IMU 11 1 that indicates that the activity level of the subject has changed.
  • Figure 9 shows a plot of an ECG signal trace for a subject when jogging.
  • the ECG signal has a lower signal-to-noise ratio than Figure 8.
  • the amplitude of the R- peaks vary and there is more noise between the R-peaks.
  • the IMU 11 1 detects that the user is now jogging and outputs a signal representative of the new activity level to the controller 103, e.g. the IMU 111 may output a value of “3”.
  • the controller 103 identifies from the received signal that the user has an activity level associated with a lower signal-to-noise ratio for the ECG signal.
  • the controller 103 adjusts the threshold level based on the received signal so as to optimise the peak removal process for the signal-to-noise ratio of the ECG signal.
  • steps S101 to S105 use the adjusted threshold level.
  • the adjusted threshold level is used until another signal is received by the controller 103 from the IMU 11 1 that indicates that the activity level of the subject has changed.
  • Figure 10 shows a plot of an ECG signal trace for a subject when running.
  • the ECG signal has a lower signal-to-noise ratio than Figures 8 and 9.
  • the amplitude of the R-peaks vary and there is more noise between the R-peaks.
  • the IMU 11 1 detects that the user is now running and outputs a signal representative of the new activity level to the controller 103, e.g. the IMU 111 may output a value of “4”.
  • the controller 103 identifies from the received signal that the user has an activity level associated with a lower signal-to-noise ratio for the ECG signal.
  • the controller 103 adjusts the threshold level based on the received signal so as to optimise the peak removal process for the signal-to-noise ratio of the ECG signal.
  • the threshold level is only adjusted when the activity level for the subject changes and a signal representing the change in activity level is received from the IMU 111. This is computationally more efficient than continually adjusting the threshold level.
  • the controller 103 receives the information characteristic of the subject from the user electronic device 300.
  • the controller 103 may also directly obtain the information without the use of the user electronic device 300.
  • the user electronic device 300 is configured to launch an application via which the subject or other user can input information characteristic of the subject.
  • the information characteristic of the subject may include one or more of the age, weight, body fat level, gender, ethnicity, fitness level, diet, medical history, or lifestyle of the subject.
  • the information is not required to be manually input by the user and instead could be automatically obtained by the user electronic device 300 or the electronics module 100 from a data source such as biosignal data for the subject.
  • the controller 103 uses the information to determine a likely signal-to-noise ratio of the ECG signal.
  • the controller 103 adjusts the threshold level based on the likely signal-to-noise ratio. Subsequent iterations of steps S101 to S105 use the adjusted threshold level.
  • the adjusted threshold level is used until further information is received by the controller 103 indicating a change in the characteristics of the subject. This information may indicate a change in, for example, the age or weight of the subject of may indicate that a different subject is now using the electronics module 100.
  • the subject specific information includes both the information characteristic of the subject and the activity level of the subject.
  • User electronic devices in accordance with the present invention are not limited to mobile phones or tablets and may take the form of any electronic device which may be used by a user to perform the methods according to aspects of the present invention.
  • the user electronic device 300 may be a electronics module such as a smartphone, tablet personal computer (PC), mobile phone, smart phone, video telephone, laptop PC, netbook computer, personal digital assistant (PDA), mobile medical device, camera or wearable device.
  • the user electronic device 300 may include a head-mounted device such as an Augmented Reality, Virtual Reality or Mixed Reality headmounted device.
  • the user electronic device 300 may be desktop PC, workstations, television apparatus or a projector, e.g. arranged to project a display onto a surface.
  • Figure 11 provides a flow diagram for an example method performed by the controller 103 for calculating the R-R intervals from the digital signals stored in the FIFO data buffer. This method can use the threshold level set according to the example of Figure 7.
  • step S201 the controller 103 reads signal values from the data buffer.
  • Each of the signal values is a value that represents the amplitude of the ECG signal at a particular time point.
  • step S202 the controller 103 detrends the signal values so as to remove baseline wander and/or other low frequency components. In an example operation, the controller 103 calculates the trend in the signal values and then subtracts the calculated trend from each of the signal values.
  • Calculating the trend comprises identifying the maximum and minimum signal values read from the data buffer.
  • the maximum signal value is added to a buffer that stores the maximum signal values obtained over time.
  • the minimum signal value is added to a buffer that stores the minimum signal values obtained over time.
  • the current trend is then calculated by calculating the average of the maximum value stored in the buffer of maximum signal values and the minimum value stored in the buffer of minimum signal values.
  • the detrended signal values are calculated by subtracting the calculated current trend from each of the signal values.
  • the detrended signal values are added to a FIFO detrended signal buffer.
  • step S203 the detrended signal values are filtered.
  • the filtering is performed to remove components from the signal that do not resemble R-peaks.
  • a bandpass filter centred around the frequency associated with the shape and width of the R-peak can be used to perform this task.
  • Some filtering approaches use a bandpass filter with a central frequency in the range of 17 to 19 Hz.
  • HR or FIR filters may be used, however, they are generally not effective due to ripples and lobes that may be present around the R-peaks in the ECG signal. The interaction between these secondary peaks and other components of the ECG signal can lead to ambiguity in the identity of the actual main peak.
  • Preferred bandpass filtering approaches analyse a signal of the instantaneous amplitude associated with the R-peak frequency. These approaches exploit the fact that R-peaks are approximately symmetrical features which means that the location of the peak in the spectral amplitude is normally close to the location of the centre of the R-peak itself.
  • the signal of instantaneous amplitude can be obtained using a complex filter and by calculating the absolute magnitude of the real and imaginary component for each filtered signal value.
  • the complex filter used is a complex Morlet wavelet.
  • the Morlet wavelet has optimal frequency resolution due to its Gaussian envelope.
  • the Morlet wavelet is also useful because it is symmetrical across the y-axis which means that only half of the filter coefficients need to be stored in RAM.
  • the filtered signal values are added to a FIFO filtered signal buffer.
  • the controller 103 determines whether at least N filtered signal values have been obtained.
  • N is a number that may be selected by the skilled person as desired to ensure that there are likely to be a certain desired number of peaks within the window of filtered signal values.
  • N may be selected such that the filtered signal buffer contains at least 4 seconds of data to ensure that there are at least 2 peaks in any window.
  • Step S101 If less than N samples of filtered signal values have been obtained then the method returns to step S101 so that additional samples are gathered, filtered, and added to the filtered signal buffer. Steps S201 to S204 are repeated until the N signal values are obtained.
  • step S205 If N or more samples of the filtered signal values have been obtained, the method proceeds to step S205.
  • step S205 the controller 103 detects peaks in the filtered signal values.
  • the controller 103 is identifying any peaks, including small and spurious peaks, in the filtered signal values.
  • the peak detection process identifies local maxima in the signal values. Peak detection can be performed by simply looking for negative gradients in the filtered signal values.
  • step S206 the controller 103 removes detected peaks that have an amplitude less than a threshold level.
  • the thresholding process is intended to remove peaks that are not R-peaks in the ECG signal.
  • the thresholding level is determined according to an adjustable threshold value multiplied by the average spectral power for the filtered signal values. Using the average spectral power enables the thresholding level to adapt based on the power of the signal.
  • the adjustable threshold value can be set according to the method of Figure 7.
  • R-R intervals are calculated for the remaining peaks.
  • R-R intervals are calculated by calculating the difference between time stamps for consecutive R-peaks. Only one R-R interval may be determined if only one R-peak remains after step S106. The R-R interval will be determined using the timestamp of the last R-peak found in the previous window of data.
  • One or more additional steps may be performed prior to step S207 to such as to check the remaining peaks after step S206 and remove or compensate for spurious remaining peaks.
  • spurious peaks may be due to noise spikes, ectopic beats or other ECG components.
  • An example process for detecting spurious peaks is disclosed in Mateo J, Website P. Analysis of heart rate variability in the presence of ectopic beats using the heart timing signal. IEEE Trans Biomed Eng. 2003 Mar;50(3):334-43. The above examples refer primarily to removing peaks in an ECG signal, but the present disclosure is not limited to this particular example.
  • the peak detection process can be applied to other biological signals such as bioimpedance signals. Bioimpedance signals include impedance plethysmography signals.
  • a method and electronics module for detecting R-peaks in an electrocardiogram, ECG, signal for a subject.
  • Subject specific information indicative of the signal- to-noise ratio of the ECG signal is obtained (S101).
  • ECG signal values for the subject are obtained (S102).
  • the ECG signal values are filtered (S103).
  • One or more candidate R-peaks in the filtered ECG signal values are detected (S104).
  • One or more detected candidate R-peaks that have an amplitude less than a threshold level are removed (S105).
  • the threshold level is determined at least in part according to the subject specific information.
  • the method may also be used with other biological (bio) signals such as bioimpedance signals.
  • the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors.
  • These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

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  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)

Abstract

La présente invention concerne un procédé et un module électronique pour détecter des pics dans un signal biologique pour un sujet tel qu'un signal indicatif d'un rythme cardiaque du sujet. Les informations spécifiques au sujet indicatrices du rapport signal-à-bruit du signal sont obtenues (S101). Les valeurs de signal pour le signal sont obtenues (S102). Les valeurs de signal sont filtrées (S103). Un ou plusieurs pics candidats dans les valeurs de signal filtrées sont détectés (S104). Un ou plusieurs pics candidats détectés qui présentent une amplitude inférieure à un niveau seuil sont retirés (S105). Le niveau seuil est déterminé au moins en partie en fonction des informations spécifiques au sujet.
PCT/GB2021/052998 2020-11-23 2021-11-19 Procédé et système de détection de pics dans un biosignal WO2022106833A1 (fr)

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GB2018355.4A GB2601177A (en) 2020-11-23 2020-11-23 Method and system for detecting peaks in a signal indicative of a heartrate
GB2018355.4 2020-11-23
GBGB2112762.6A GB202112762D0 (en) 2020-11-23 2021-09-08 Method and system for detecting peaks in a biosignal
GB2112762.6 2021-09-08

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GB2612979A (en) * 2021-11-17 2023-05-24 Prevayl Innovations Ltd Method and system for measuring and displaying biosignal data to a wearer of a wearable article

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GB202112762D0 (en) 2021-10-20
GB202018355D0 (en) 2021-01-06
GB2616763A (en) 2023-09-20

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