Methods and systems for polarized photoplethysmography (PPG) and biosignal analysis
The disclosure is directed to a system and a method for biosignal detection, the method including emitting an electromagnetic spectral emission, including polarized light, that is reflected on a surface, collecting attributes from the reflected electromagnetic spectral emission, calculating Stokes parameters based on the collected attributes, determining at least one signal based on the Stokes parameters, and analyzing the at least one signal to estimate health-related information, wherein the collected attributes comprise at least one of a light intensity of a predetermined polarization state, a light intensity for a wavelength range, and a light intensity for multiple pixels.
1 . A method for biosignal detection and analysis, the method comprising:
emitting, from a light source positioned on a substrate, an electromagnetic spectral emission, including polarized light, that is reflected on a surface,
collecting attributes from the reflected electromagnetic spectral emission by at least one pixel positioned on the substrate,
calculating Stokes parameters based on the collected attributes,
obtaining a parameter representing a diattenuation based on the Stokes parameters, the parameter indicating one or more ratios of intensities of different polarization states,
determining, based on the parameter representing the diattenuation, at least one time-varying biosignal, wherein a first amplitude of the parameter representing the diattenuation is determined based on a first time point and a second amplitude of the parameter representing the diattenuation is determined based on a second time point after the first time point, and
analyzing the at least one time-varying biosignal to estimate health-related information,
wherein the collected attributes comprise at least one of a light intensity of a predetermined polarization state, a light intensity for a wavelength range, or a light intensity for multiple pixels.
2 . The method of claim 1 , wherein the surface on which the electromagnetic spectral emission is reflected is a living tissue.
3 . The method of claim 1 , wherein the electromagnetic spectral emission is at least one of a collimated emission, a diffused emission, a polarized emission, a multispectral emission, a pulsed emission, a continuous emission, a visible spectrum emission or an infrared emission.
4 . The method of claim 1 , wherein the at least one pixel detects a wavelength range and at least one polarization state.
5 . The method of claim 4 , wherein the at least one pixel comprises hardware filters configured to allow the wavelength range and the at least one polarization state to pass through while restricting other wavelength ranges and polarization states to pass through.
6 . The method of claim 1 , wherein the attributes collected from the reflected electromagnetic spectral emission comprise at least one of a spectrum, a polarization state, a light intensity, or a depth.
7 . The method of claim 1 , wherein calculating the Stokes parameters is performed for at least one pixel using intensity data of the at least one pixel using a polarization state and wavelength range filter.
8 . The method of claim 1 , wherein the at least one time-varying biosignal is determined based on at least one of spectral changes or a depth estimation.
9 . The method of claim 1 , wherein the at least one time-varying biosignal is analyzed to estimate the health-related information by processing the reflected electromagnetic spectral emission with a polarized emission.
10 . The method of claim 1 , wherein the polarized light is comprised of at least one of linear polarization, circular polarization, or elliptical polarization.
11 . The method of claim 1 , wherein the health-related information includes at least one of heart-rate information, respiratory rate information, hypertension signatures, red blood cell concentration information, blood saturation information, a continuous blood pressure, pulse rate information, a pulse pressure, cardiovascular conditions, stroke volume information, cardiac output information, a one lead electrocardiogram (ECG), a systematic vascular resistance, a cardiac index, a mean arterial pressure, antioxidants, melanoma information, triglyceride information, cholesterol information, or beta carotene information.
12 . A system for biosignal detection and analysis, the system comprising:
a light source positioned on a substrate and configured to emit an electromagnetic spectral emission, including polarized light, reflected on a surface;
a detector configured to collect attributes of the reflected electromagnetic spectral emission by at least one pixel positioned on the substrate; and
a processor configured to:
calculate Stokes parameters based on the collected attributes,
obtain a parameter representing a diattenuation based on the Stokes parameters, the parameter indicating one or more ratios of intensities of different polarization states,
determine, based on the parameter representing the diattenuation, at least one time-varying biosignal, wherein a first amplitude of the parameter representing the diattenuation is determined based on a first time point and a second amplitude of the parameter representing the diattenuation is determined based on a second time point after the first time point, and
analyze the at least one time-varying biosignal to estimate health-related information,
wherein the collected attributes comprise at least one of a light intensity of a predetermined polarization state, a light intensity for a wavelength range, or a light intensity for multiple pixels.
13 . The system of claim 12 , wherein the at least one time-varying biosignal is determined based on at least one of spectral changes or a depth estimation.
14 . The system of claim 12 , wherein the polarized light is comprised of at least one of linear polarization, circular polarization, or elliptical polarization.
15 . The system of claim 12 , wherein the health-related information includes at least one of heart-rate information, respiratory rate information, hypertension signatures, red blood cell concentration information, blood saturation information, a continuous blood pressure, pulse rate information, a pulse pressure, cardiovascular conditions, stroke volume information, cardiac output information, a one lead electrocardiogram (ECG), a systematic vascular resistance, a cardiac index, a mean arterial pressure, antioxidants, melanoma information, triglyceride information, cholesterol information, or beta carotene information.
16 . A method for biosignal detection and analysis, the method comprising:
emitting, from a light source positioned on a substrate, polarized light that is reflected on a surface,
detecting the reflected polarized light using a pixel positioned on the substrate having four polarizing filters,
calculating Stokes parameters based on attributes of the polarized light identified using the four polarizing filters,
obtaining a parameter representing a diattenuation based on the Stokes parameters, the parameter indicating one or more ratios of intensities of different polarization states,
determining, based on the parameter representing the diattenuation, at least one time-varying biosignal, wherein a first amplitude of the parameter representing the diattenuation is determined based on a first time point and a second amplitude of the parameter representing the diattenuation is determined based on a second time point after the first time point, and
analyzing the at least one time-varying biosignal to estimate health-related information,
wherein the attributes comprise at least one of a light intensity of a predetermined polarization state, a light intensity for a wavelength range, or a light intensity for multiple pixels.
17 . The method of claim 16 , wherein the at least one time-varying biosignal is determined based on at least one of spectral changes or a depth estimation.
18 . The method of claim 16 , wherein the polarized light is comprised of at least one of linear polarization, circular polarization, or elliptical polarization.
19 . The method of claim 16 , wherein the health-related information includes at least one of heart-rate information, respiratory rate information, hypertension signatures, red blood cell concentration information, blood saturation information, a continuous blood pressure, pulse rate information, a pulse pressure, cardiovascular conditions, stroke volume information, cardiac output information, a one lead electrocardiogram (ECG), a systematic vascular resistance, a cardiac index, a mean arterial pressure, antioxidants, melanoma information, triglyceride information, cholesterol information, or beta carotene information.