Multi-band PPG Wearable Device Signal Quality Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wearable devices with single-frequency band photoplethysmography (PPG) modules face issues such as distorted measurements due to displacement and limited sensing information, leading to misjudgments in monitoring health status in real time.
Innovation Solution
A wearable device with a micro spectrometer that emits mixed light across multiple spectrum frequency bands, using a spectrum sensing unit to generate a spectrum data set of light intensity values, and an arithmetic unit that selects and interprets data based on signal quality, including signal-to-noise ratio, to optimize PPG data interpretation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a traditional PPG module emits a light of single frequency band, then the device structure is simple, but the sensing information is not rich enough leading to misjudgments
Solution Approach 1:
The patent segments the light spectrum into multiple frequency bands (e.g., green, red, infrared) and uses separate light emitting units for each band. This segmentation allows the system to collect rich sensing information from different tissue depths while maintaining a structured, modular device architecture that isn't overly complex
Solution Approach 2:
The patent transitions from single-frequency-band sensing to multi-frequency-band sensing, adding the dimension of spectral diversity. This dimensional expansion enables the system to obtain comprehensive physiological information without proportionally increasing device complexity, as the additional bands provide complementary information
2Measurement precision
If the wearable device displaces from the skin, then the incident distance changes, but the measuring result becomes distorted
Solution Approach 1:
The patent changes the parameter of light frequency band to multiple bands instead of relying on a single band. Different frequency bands penetrate tissue to different depths and are affected differently by displacement. By measuring across multiple bands simultaneously, the system can identify and compensate for displacement effects, maintaining measurement precision even when incident distance changes
Solution Approach 2:
The patent implements feedback mechanisms where the system continuously monitors signal quality across multiple frequency bands and uses this information to adjust measurements in real-time. When displacement is detected through signal quality degradation in certain bands, the system can compensate by relying more on bands less affected by the displacement, maintaining accurate measurements
3Productivity
If a light sensor converts outgoing light of single frequency band, then the signal processing is simple, but the health status monitoring is not effective in real time
Solution Approach 1:
The patent segments the signal processing into multiple parallel channels, each handling a specific frequency band. This segmentation allows the system to process multiple bands simultaneously rather than sequentially, enabling real-time health monitoring while keeping each individual processing channel relatively simple and manageable
Solution Approach 2:
The patent performs preliminary separation and preliminary processing of different frequency bands before final integration. By pre-organizing the multi-band signals and applying band-specific processing in advance, the system reduces the computational burden during real-time analysis, improving monitoring effectiveness without excessive complexity
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
The solution enhances the accuracy of physiological parameter estimation, including blood cell counts, hemoglobin, and blood pressure, by reducing distortion from displacement and improving data interpretation with AI learning and image recognition technologies.
Implementation Method 1
A photoplethysmography (hereafter PPG) module is usually set on the bottom of a main body 11 of the wearable device. In the conventional technical means, a traditional PPG module 110 only emits a light of single frequency band into inside skin at single time point, then detects an intensity change of outgoing light from the inside skin
Implementation Method 2
When a light beam of certain wavelength irradiates on the skin surface, vasoconstriction and vasodilatation caused by each heartbeat will affect transmission of the light (such as to perform transmissive PPG to the light passing through fingertips) or reflection of the light (such as to perform reflective PPG to the light reflected from near wrist surface). When the light irradiates the skin tissue then is reflected to a light sensor, the intensity of the light will attenuate to a certain extent
Data Source
AI summary
A wearable device and a method for selecting and interpreting light intensity data values applicable thereto. The wearable device includes a light emitting unit and a spectrum sensing unit. The method includes steps of: controlling the light-emitting unit to simultaneously emit a mixed light including multiple spectrum frequency bands to enter inside skin of the user; controlling the spectrum sensing unit to sense the intensity of an outgoing light from inside skin of the user at a series of sampling time to generate a spectrum data set including a plurality of groups of frequency band-light intensity data values; and selecting at least one of a first group of frequency band-light intensity data values satisfying a signal quality index in the spectrum data set to perform a data interpretation at a first judgment time point.