Device, system and method for detection and processing of heartbeat signals

• US 9,833,155 B2
• Filed: 07/24/2015
• Issued: 12/05/2017
• Est. Priority Date: 01/24/2013
• Status: Active Grant

• Current Assignee: Empatica SRL (Empatica, Inc. (Massachusetts))
• Original Assignee: Empatica SRL (Empatica, Inc. (Massachusetts))
• Inventors: Tognetti, Simone, Cenci, Ivan, Resnati, Daniele, Garbarino, Maurizio, Lai, Matteo
• Primary Examiner(s): MANUEL, GEORGE C
• Application Number:
  US14/808,488
• Publication Number:
  US 20150327787A1
• Time in Patent Office: 865 Days
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/0071 by measuring fluorescence emission
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/0533 Measuring galvanic skin response
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths

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 opt cal 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.

Claims

1. A heart beat detection device, comprising:

at least one optical sensor unit configured to be placed on a person'"'"'s skin, the optical sensor unit including;

a light emitter and a corresponding light receiver, the light emitter configured for emitting light onto the person'"'"'s skin, the light receiver configured to convert light received from the skin into an electric signal,

the sensor unit further including electrically adjustable optical filters connected to the emitter, to the receiver, or to both,

the electrically adjustable optical filters configured to select, upon operation, a desired wavelength of the light emitted by the light emitter, of the light receivable by the light receiver, or both,

wherein the electrically adjustable optical filters include Fabry-Perot monochromators.

2. The heart beat detection device according to claim 1, further comprising a processing block configured for receiving the electric signal from the light receiver and to control the electrically adjustable optical filters, the processing block further configured for selecting one of:

a first mode for measuring a first signal depending on the variation in blood volume using the physical principles of absorption; and

a second mode for measuring a second signal depending on the variation in blood volume using the physical principles of fluorescence,

the processing block further configured for processing the first or the second signal to generate a signal representing the heart rate.

3. The heart beat detection device according to claim 1, further comprising a processing block configured for receiving the electric signal from the light receiver for controlling the electrically adjustable optical filters for optimizing the amplitude of the received light signal.

4. The heart beat detection device according to claim 1, further comprising two optical sensor units arranged at a distance from each other and connected to a signal processing block,

the signal processing block configured for estimating a blood propagation time between the two optical sensor units,

the signal processing block configured for modifying the signal detected by at least one optical sensor unit depending on variations in the estimated blood propagation time.

5. The heart beat detection device according to claim 1, further comprising:

an electrical detection system configured for measuring the galvanic response of the skin; and

a processing block configured to generate a signal associated with the heart beat of the person, the signal based on the measured galvanic response of the skin and the signal detected by the at least one optical sensor unit.

6. The heart beat detection device according to claim 1, further comprising a system configured for measuring the acceleration of the device and a processing block configured for, based on the measured acceleration, modifying the signal detected by the at least one optical sensor unit.

7. The heart beat detection device according to claim 1, further comprising a power supply element for the emitter of the at least one optical unit, the power supply element configured for receiving commands from a processing block, the processing block configured for receiving the electrical signal received from the receiver, the power supply element configured for varying a luminosity of the emitter for keeping the light received from the skin above a predefined minimum threshold.

8. A system for detecting and processing physiological data, comprising at least one device according to any one of the preceding claims connected by means of a wireless interface to a data processing and transmission unit which receives the data from the device and processes it.

9. A system according to claim 8, characterized in that the processing and transmission unit communicates with a remote terminal.

10. A system according to claim 9, characterized in that the processing and transmission unit communicates with the remote terminal via the Internet.

11. A system according to claim 8, characterized in that said device is in the form of a device to be fixed to the wrist by means of a strap and that the said processing and transmission unit is a suitably programmed tablet or smart phone.

12. A method for increasing the signal/noise ratio of an electric signal for detecting heart beat optically by means of an optical reflection sensor unit, the method comprising:

differentiating, by means of an adaptive numerical filter, between the effects of at least two light wavelengths by means of electrically adjustable optical filters, a first wavelength of the two light wavelengths associated with operation of the optical reflection sensor unit in an absorption mode, a second wavelength of the two light wavelengths associated with operation of the optical reflection sensor unit in a fluorescence mode; and

processing the corresponding signals received from the optical reflection sensor unit so as to obtain the electric signal representing the heart beat,

wherein the electrically adjustable optical filters are adjusted so as to tune dynamically the two (or more) wavelengths in order to maximize signal levels of the optical reflection sensor unit.

13. The method according to claim 12, wherein the optical reflection sensor unit is a first optical reflection sensor unit, the first optical reflection sensor unit being arranged at a distance from a second optical reflection sensor unit, the method further comprising:

estimating a blood propagation time between the first optical reflection sensor unit and the second optical reflection sensor unit; and

modifying the corresponding signal detected by the first optical sensor unit based on variations in the blood propagation time.

14. The method according to claim 12, further comprising:

obtaining a three-dimensional acceleration signal; and

subtracting, via the adaptive numerical filter, the three-dimensional acceleration signal from the corresponding signal.

15. The method according to claim 12, further comprising:

measuring a galvanic response of a person'"'"'s skin;

obtaining a first signal representing the heart beat based on the galvanic response; and

combining the first signal with the corresponding signal detected by the optical reflection sensor unit.

16. The method according to claim 12, further comprising:

estimating physiological parameters of a person based on an electric signal representing the heart beat, wherein the physiological parameters include at least one of a stress state, a level of physical activity and physical condition, a quality of sleep and/or an excitation level.