Contactless system and method for assessing and/or determining hemodynamic parameters and/or vital signs
Inventors
Assignees
Publication Number
US-11426076-B2
Publication Date
2022-08-30
Expiration Date
2040-11-25
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Abstract
A contactless system for assessing and/or determining hemodynamic parameters and/or vital signs is featured. The system includes one or more contactless light sources configured to emit light incident on a moving living subject at one more wavelengths absorbed by one or more chromophores associated with spontaneous hemodynamic oscillations in a predetermined area of the living subject. The system includes a camera subsystem including one or more cameras configured to receive reflected light from the predetermined area of the moving living subject and configured to track motion of the predetermined area of the living subject within a field of view of the camera subsystem and configured to generate a time sequence of images of the predetermined area of the living subject. A controller is coupled the one or more light sources and the camera subsystem and is configured to acquire the time sequence of images and configured to generate one or more non-contact PPG waveforms and to assess and/or and determine one or hemodynamic parameters and/or vital signs from the one or more non-contact PPG waveforms. One or more polarizers are preferably each coupled to one of the one or more light sources are preferably configured to polarize the light to a polarized state such that the polarized light in the polarized state diffuses into the tissue in the predetermined area at a predetermined depth range and the polarized light is maintained in the polarized state at the predetermined depth range. A detector polarizer is preferably coupled to each of the one or more cameras and is configured to discriminate the light maintained in the polarized state and at the predetermined depth range and configured to generate the time sequence of images of the predetermined area with improved signal quality of the resulting non-contact PPG waveform.
Core Innovation
The invention is a contactless system and method for assessing and determining hemodynamic parameters and vital signs of one or more moving living subjects. The system includes one or more contactless light sources configured to emit light at specific wavelengths absorbed by chromophores associated with spontaneous hemodynamic oscillations within a predetermined area of the living subject's exposed skin. A contactless camera subsystem with one or more cameras receives reflected light and tracks the motion of the predetermined area within the field of view. A controller acquires a time sequence of images and generates non-contact photoplethysmography (PPG) waveforms to assess and/or determine hemodynamic parameters and vital signs from these waveforms.
The system incorporates polarizers coupled to the light sources to polarize the emitted light into a polarized state. This polarized light diffuses into tissue at a predetermined depth range and maintains its polarization at that depth. Corresponding detector polarizers are coupled to each camera to discriminate light that is maintained in the polarized state at the predetermined depth versus light that has lost polarization, resulting in images with improved signal quality of the non-contact PPG waveform. This configuration facilitates effective real-time or remote monitoring of subjects without direct physical contact, even if the subject is moving or located at a distance from the system.
The problem addressed arises from conventional methods that require direct sensor contact with the skin, which can be intrusive, uncomfortable, may cause skin irritation, and affect physiological readings by causing anxiety or nervousness. Conventional contactless methods either rely on complex and cumbersome frequency domain analyses or require the subject to be stationary, limiting their utility for moving subjects. Existing systems also fail to robustly track motion or maintain signal quality under movement. This invention solves the need for a less complex, non-intrusive, and accurate contactless system and method for assessing hemodynamic parameters and vital signs of moving living subjects using time domain analysis and advanced polarization techniques to enhance signal quality.
Claims Coverage
The patent includes two independent claims directed to a contactless system and method for assessing and determining hemodynamic parameters and vital signs.
Contactless system with motion-tracking camera subsystem and polarized light sources
A system comprising contactless light sources configured to emit light onto a moving living subject; a camera subsystem with one or more cameras configured to receive reflected light from a predetermined area, track that area’s motion within the field of view, and generate a time sequence of images; a controller that acquires the image sequence, generates non-contact PPG waveforms using time domain analysis, and determines hemodynamic parameters or vital signs from those waveforms; polarizers on the light sources to polarize emitted light to a polarized state diffusing to a predetermined tissue depth and maintaining polarization; and detector polarizers on the cameras to discriminate polarized light maintained at the predetermined depth from depolarized light, thereby generating improved quality image sequences.
Method for contactless assessment with motion tracking and polarized light
A method comprising contactlessly emitting light onto a living subject; following and tracking a predetermined area within one or more fields of view as the subject moves, generating a time sequence of images; acquiring the images; generating non-contact PPG waveforms using time domain analysis; determining hemodynamic parameters or vital signs from the waveforms; polarizing incident light to maintain polarization at a predetermined tissue depth; discriminating maintained polarized light from depolarized light reflected from the tissue; and generating image sequences of the predetermined area with improved signal quality.
These independent claims cover inventive features involving contactless light emission with polarization, motion tracking using a camera subsystem generating time series images of a moving living subject’s predetermined area, processing images via time domain analysis to generate non-contact PPG waveforms, and discriminating polarized light to improve signal quality for accurate hemodynamic parameter assessment.
Stated Advantages
Enables accurate, contactless assessment and determination of hemodynamic parameters and vital signs of moving living subjects without physical contact.
Reduces subject discomfort and anxiety associated with sensor contact, preventing altered physiological readings and skin irritation.
Improves signal quality of non-contact PPG waveforms by using polarized light and detector polarizers discriminating light at specific tissue depths.
Uses time domain analysis, avoiding complex frequency domain methods and cumbersome two-dimensional hemodynamic maps, resulting in a less complex, more efficient system.
Provides flexibility to track a moving subject or subjects at varying distances using fixed, wide field, composite field, or movable cameras including diverse mounting options.
Documented Applications
Real-time assessment and determination of hemodynamic parameters and vital signs such as heart rate, resting heart rate, heart rate variability, respiration rate, and oxygen saturation of moving living subjects.
Remote monitoring of subjects located meters away in environments such as hospitals, airports, train stations, stadiums, gyms, rooms, or any type of facility.
Population-wide monitoring of large groups of living subjects within a predefined environment using composite fields of view from multiple cameras or wide and moving fields of view.
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