Device, system and method for detection and processing of heartbeat signals
Inventors
TOGNETTI, SIMONE • CENCI, IVAN • RESNATI, DANIELE • GARBARINO, MAURIZIO • LAI, MATTEO
Assignees
Publication Number
US-11389074-B2
Publication Date
2022-07-19
Expiration Date
2034-01-21
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Abstract
A heart beat detection device comprises at least one optical reflection sensor to be positioned on the skin of a person. The sensor unit is provided with a light emitter and a corresponding light receiver which converts the light reflected by the skin into an electric signal and comprises electrically adjustable optical filters connected to the emitter, to the receiver or to both of them in order to select, upon operation, a desired light wavelength and perform processing of the signals thus obtained in order to reinforce the heart beat signal. A system with this device and a detection method are also described.
Core Innovation
The invention relates to a heart beat detection device comprising at least one optical reflection sensor unit placed on the skin of a person. The sensor includes a light emitter and a light receiver which converts light reflected by the skin into an electrical signal. The device features electrically adjustable optical filters connected to the emitter, receiver, or both, allowing selection of a desired light wavelength during operation to improve processing of the heart beat signal by reinforcing it.
The problem addressed is that optical heart rate monitors, particularly reflection-type devices placed on areas such as the wrist, suffer from low signal-to-noise ratio caused by small variations in reflected light due to blood flow and significant noise from movements of the skin and underlying tissues. Prior art attempts using fixed wavelength light sources, dual wavelengths, or accelerometers do not sufficiently address noise caused by motion or variable skin characteristics, resulting in unsatisfactory heart rate detection especially during typical daily activities or exercise.
The invention solves this by providing tunable optical filters that can dynamically select light wavelengths optimized for absorption and fluorescence by oxyhaemoglobin. By alternating and combining signals obtained at these wavelengths, the device improves signal-to-noise ratio. Moreover, it adjusts emission intensity to optimize signal amplitude while conserving battery life, and incorporates other sensors such as accelerometers and galvanic skin response electrodes to further process and filter noise caused by mechanical deformations and movements. A system and method for processing the combined signals to maximize measurement accuracy in the presence of disturbances are also described.
Claims Coverage
The patent includes several independent claims focused on the heart beat detection device and its integrated features.
Optical sensor unit with electrically tunable optical filters
The device comprises at least one optical sensor unit with a light emitter and receiver, and at least one optical filter tunable to different wavelengths to filter emitted and reflected light, operating in modes to maximize oxyhaemoglobin absorption and fluorescence.
Use of Fabry-Perot monochromator as optical filter
The optical filter utilized in the device comprises a Fabry-Perot monochromator allowing precise tuning of wavelengths.
Processing unit control of filter modes for heart rate determination
A processing unit controls the optical filter operation modes (absorption and fluorescence) and processes the electric signals to determine the heart rate.
Optimization of signal amplitude via processing unit
The processing unit receives electric signals from the receiver and controls optical filters to optimize the amplitude of the received signal for better detection.
Dual optical sensor units for blood propagation time estimation
The device may include two optical sensor units spaced apart for measuring blood propagation time between sensors, with a signal processing unit modifying signals based on variations in this propagation time to improve noise filtering.
Incorporation of galvanic skin response measurement
An electrical detection system measures the skin's galvanic response, and a processing unit combines this signal with the optical signal to enhance heart beat detection.
Use of acceleration measurement for noise compensation
The device includes an acceleration measurement system and a processing unit that modifies the electric signal based on detected movement to reduce motion noise.
Power supply control for emission luminosity
A power supply element controlled by the processing unit varies the light emitter's luminosity to maintain the electric signal above a predefined minimum threshold, optimizing power use.
Separate optical filters for emitter and receiver
The device may have a first optical filter arranged with the emitter to filter emitted light and a second optical filter with the receiver to filter reflected light within specific wavelength ranges.
Combination of signals from absorption and fluorescence modes
The processing unit receives signals from both absorption and fluorescence wavelength modes and combines them to improve the signal/noise ratio for heart beat determination.
The independent claims collectively define a heart beat detection device that uses tunable optical filters operating in absorption and fluorescence modes, combined with signal processing including dual sensors, galvanic skin response, acceleration measurement, and controlled emission intensity, to improve detection accuracy and noise filtering.
Stated Advantages
Improved signal/noise ratio in heart beat detection by dynamically tuning optical wavelengths for absorption and fluorescence of oxyhaemoglobin.
Adaptability to different skin types and conditions by adjusting emission and detection wavelengths, compensating for optical interference from skin characteristics.
Reduction of noise caused by tissue and sensor movement via filtering based on wavelength selection and use of accelerometer signals.
Optimized power consumption by adjusting emitted light intensity to maintain minimally sufficient signal amplitude, extending battery life.
Ability to operate both absorption and fluorescence detection modes and combine their signals for more reliable heart beat measurement.
Enhanced noise reduction by combining optical measurement with galvanic skin response and acceleration data.
Documented Applications
Wearable heart rate monitors positioned on the wrist, such as wristwatch-like devices, for continuous and prolonged heart beat detection during daily activities.
Remote physiological monitoring systems where data from the sensor device is transmitted wirelessly to processing units, servers, or terminals for health status assessment including stress level, physical activity, sleep quality, and excitation level.
Sport and fitness applications where reliable heart rate detection is needed despite movement and physical activity.
Medical and clinical monitoring systems utilizing multi-sensor data fusion (optical, galvanic skin response, acceleration) for improved physiological parameter measurement accuracy.
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