Virtual Sensor PPGI System for Spatial Perfusion Analysis
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Solution Overview
Problem
Existing photoplethysmography imaging systems are limited in their ability to perform real-time, spatial cardiovascular monitoring due to restricted measurement areas, noise reduction methods, and reliance on darkroom settings, which hinders their applicability in clinical environments.
Innovation Solution
A system and method utilizing virtual sensors and digital signal processing to detect and measure arterial and venous blood pulse waveforms simultaneously at various body parts, allowing for spatial perfusion analysis and generation of derivative visualizations, including the use of contact photoplethysmography sensors for reference waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple BPW signals are measured simultaneously at various body parts using PPGI system, then spatial perfusion analysis capability is improved, but device complexity and noise reduction difficulty increase
Solution Approach 1:
The patent divides the imaging area into multiple regions of interest (ROIs), each assigned to a virtual sensor. This segmentation allows simultaneous monitoring of multiple body parts (e.g., carotid artery, jugular vein, peripheral arteries) without requiring a single complex sensor system, thereby improving spatial perfusion analysis capability while managing device complexity through modular region-based processing.
Solution Approach 2:
The patent introduces digital signal processing (DSP) as an intermediary between the camera system and the physiological measurements. The DSP unit processes raw video signals, extracts BPW waveforms, and generates spatial perfusion maps, effectively mediating between the simple optical sensing system and the complex multi-parameter physiological analysis requirements.
2Measurement precision
If advanced digital signal processing is used to extract BPW from noise, then measurement precision is improved, but processing time and computational load increase
Solution Approach 1:
The patent applies preliminary spatial filtering and region-of-interest selection before full BPW extraction. By pre-identifying relevant body regions and filtering out obvious noise sources in the video feed, the system reduces the computational burden on subsequent BPW extraction algorithms, thereby improving measurement precision without excessive processing time.
Solution Approach 2:
The patent employs periodic sampling of video frames at optimized frame rates for cardiovascular monitoring. By sampling at frequencies matched to the physiological signal characteristics (typically 30-60 fps for BPW), the system achieves sufficient measurement precision while avoiding the computational overhead of continuous high-speed processing.
3Ease of operation
If PPGI system is used in real-world clinical environments, then ease of operation is improved, but measurement reliability decreases due to ambient light and motion artifacts
Solution Approach 1:
The patent converts ambient light, traditionally considered a harmful interference, into a useful signal source. The system is designed to extract BPW information from ambient illumination reflected off the skin, eliminating the need for controlled darkroom environments. This approach improves ease of operation in clinical settings while maintaining measurement reliability through sophisticated signal processing that distinguishes physiological signals from ambient light variations.
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors signal quality metrics and adjusts processing parameters in real-time. When motion artifacts or ambient light interference is detected, the system adapts its filtering and extraction algorithms to maintain reliable measurements, thereby preserving signal quality across varying clinical environments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables comprehensive cardiovascular monitoring by providing a complete picture of blood pulse waveforms across the body, improving diagnostic capabilities and applicability in real-world clinical settings.
Implementation Method 1
Light that penetrates the surface of the skin interacts with the underlying tissues in two primary ways: scattering and absorption. When perfectly reflected and scattered by a molecule, a photon of light changes direction and possibly polarization, but retains its original energy level.
Implementation Method 2
Alternatively, a photon of light may be absorbed by certain types of molecules called 'chromophores' (such as hemoglobin and melanin), resulting in a fewer number of photons being re-emitted.
Data Source
AI summary
There is disclosed a system and method for measuring arterial and venous blood pulse waveforms (BPWs) of a subject utilizing photoplethysmography (PPG). In an embodiment, the system and method comprises: providing a plurality of virtual sensors positioned to cover a desired field-of-view of the subject, each virtual sensor adapted to detect and measure a BPW signal from an area of the subject's body and provide a BPW signal output; processing the BPW signal outputs of the plurality of virtual sensors to compare the BPWs at multiple areas of the subject's body to perform spatial perfusion analysis; and displaying at least one aggregate output based on the spatial perfusion analysis. At least one aggregate output may include a visualization of one or more perfusion patterns overlaid on a photographic image of the subject, and aggregate statistics including subject heart rate and breathing rate. The system and method may use a signal from one of the virtual sensors as a reference waveform for cardiovascular monitoring in the generation of parametric maps for assessing BPW characteristics at various parts of the body simultaneously. The system and method may also include a contact photoplethysmography (PPG) sensor, which is connected to the DSP and provides a BPW as a reference waveform for improved cardiovascular monitoring in the generation of parametric maps for assessing BPW characteristics at various parts of the body simultaneously.