Portable electronic hemodynamic sensor systems
Systems and methods are provided for extracting hemodynamic information, optionally employing portable electronic devices with optional User Interface (UI) features for system implementation. The systems and methods may be employed for acquiring hemodynamic signals and associated electrophysiological data and/or analyzing the former or both in combination to yield useful physiological indicia or results. Such hardware and software is advantageously used for non-invasively monitoring cardiac health.
1. A system comprising:
a vibration sensor configured to capture a vibrational signal comprising frequency components, wherein the vibration sensor is configured to capture the signal from skin of a subject at a location peripheral to a heart of the subject;
a processor; and
a memory on which is stored a plurality of instructions that, when executed by the processor, cause the processor to:
apply a low pass filter to resolve a pulse waveform, wherein application of the low pass filter passes frequency components of the vibrational signal from zero hertz to a low pass cutoff frequency of the low pass filter;
apply a high pass filter to resolve Embedded Frequency signals corresponding to sound of the heart, wherein application of the high pass filter passes frequency components of the vibrational signal above a high pass cutoff frequency of the high pass filter; and
calculate, using both the Embedded Frequency signals and the pulse waveform, at least one physiological parameter, wherein the physiological parameter is selected from at least one of Dicrotic Notch (DN) position of the pulse waveform, Ejection Fraction (EF) and systolic time intervals, and wherein the instructions are further adapted to cause the processor to calculate Intrinsic Frequency (IF) parameters ω1 and ω2 on each side of the DN.
2. The system of claim 1 , wherein the low pass cutoff frequency is 250 hertz.
3. The method of claim 1 , wherein the low pass filter is configured to resolve a pulse waveform having a frequency range of zero to 250 hertz.
4. The system of claim 1 , wherein the vibration sensor comprises a light source and a light sensor.
5. The system of claim 4 , wherein the light source is an LED in a smartphone camera.
6. The system of claim 4 , wherein the vibration sensor further comprises a membrane, the membrane made of a material selected to be at least partially reflective to the light source on an inner surface of the membrane.
7. The system of claim 6 , wherein the membrane comprises metal or is metalized on the inner surface.
8. The system of claim 6 , wherein the membrane material is selected to reduce light passing from an outer surf ace of the membrane to the sensor.
9. The system of claim 8 , wherein the material substantially eliminates light passing from the outer surface.
10. The system of claim 8 , wherein the membrane comprises metal or is metalized on the inner surface.
11. The system of claim 1 , further comprising an electrocardiogram (ECG) sensor, wherein the processor is further adapted for producing an ECG signal.
12. The system of claim 1 , wherein the computer processor is further adapted to calculate Ejection Fraction (EF) using the Embedded Frequency signals, the pulse waveform and an ECG signal.
13. The system of claim 1 , further comprising a ring-shaped extension from a housing of the vibration sensor.
14. The system of claim 13 , wherein the extension includes an outer ring and an inner ring, wherein the inner ring defines a ledge to limit skin depression.
15. A method comprising:
capturing, with a vibration sensor on a subject's skin at a location peripheral to the subject's heart, a vibrational signal representative of skin vibration sensed by the vibration sensor, wherein the vibrational signal comprises frequency components;
applying a low pass filter to resolve a pulse waveform, wherein applying the low pass filter comprises passing frequency components of the vibrational signal from zero hertz to a low pass cutoff frequency of the low pass filter;
applying a high pass filter to resolve Embedded Frequency signals corresponding to sound of the heart, wherein applying the high pass filter comprises passing frequency components of the vibrational signal above a high pass cutoff frequency of the high pass filter;
calculating with a computer processor, using both the Embedded Frequency signals and the pulse waveform, at least one physiological parameter; and
calculating Intrinsic Frequency (IF) parameters ω1 and ω2 with the computer processor.
16. The method of claim 15 , wherein the low pass cutoff frequency is 250 hertz.
17. The method of claim 15 , wherein the low pass filter is configured to resolve a pulse waveform having a frequency range of zero to 250 hertz.
18. The method of claim 15 , further comprising determining a Dicrotic Notch (DN) position within the pulse waveform using the Embedded Frequency signals with the computer processor.
19. The method of claim 15 , further comprising calculating Ejection Fraction (EF) with the computer processor using ω1 and ω2.
20. The method of claim 15 , wherein the vibration sensor includes a ring-shaped extension from a housing of the vibration sensor, and the method further comprises stretching the skin with the extension.
21. The method of claim 20 , wherein the extension includes an outer ring and an inner ring, and the method further comprises limiting skin depression with the inner ring.