Wearable Optical Sensor Noise Reduction via Signal Correlation
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Solution Overview
Problem
Current methods for detecting analytes in blood are invasive, inconvenient, and suffer from low signal-to-noise ratios, making it difficult to accurately measure rare or small analytes like circulating tumor cells, especially when measurements are taken non-invasively.
Innovation Solution
A wearable medical diagnostic device that transmits optical signals from within subsurface vasculature, correlating noise signals to improve the signal-to-noise ratio by determining a filtered signal based on unfiltered and noise signals, using functionalized particles and interrogating signals to detect analytes non-invasively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensing techniques are used to detect analytes, then the detection method is simple, but the signal-to-noise ratio is low making it difficult to accurately measure rare or small analytes
Solution Approach 1:
The patent segments the detection system into multiple independent components: functionalized particles that bind to target analytes, optical interrogation signals for detection, and correlation processing to separate signal from noise. This segmentation allows each component to be optimized independently, improving measurement precision without overwhelming complexity.
Solution Approach 2:
The patent introduces functionalized particles as intermediaries between the target analytes and the detection system. These particles bind to rare analytes like circulating tumor cells, amplifying the signal and enabling detection of analytes that would otherwise be too small or rare to detect with conventional techniques.
2Measurement precision
If large quantities of blood are sampled to detect rare analytes, then the detection sensitivity improves, but the invasiveness and patient compliance requirements increase
Solution Approach 1:
The patent replaces mechanical blood sampling and laboratory analysis with a non-invasive optical detection system. Optical signals penetrate tissue to detect functionalized particles in subsurface vasculature, eliminating the need for needle sticks and lab processing, thereby improving patient compliance while maintaining detection sensitivity.
3Measurement precision
If fluorescence detection techniques are used, then the detection capability is enhanced, but background noise from other tissues, cells, and molecules increases
Solution Approach 1:
The patent applies local quality by functionalizing particles with specific receptors that bind only to target analytes, and by using optical filters that selectively transmit wavelengths corresponding to the fluorophore emission. This specificity ensures that only signal from target-analyte-bound particles is detected, eliminating background noise from other tissues and molecules.
Solution Approach 2:
The patent employs periodic modulation of the optical interrogation signal and correlation processing to distinguish periodic signal from random background noise. By modulating the excitation light and detecting only the modulated fluorescence response, the system enhances analyte detection capability while suppressing continuous background fluorescence from tissues.
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 device enhances the signal-to-noise ratio, allowing for more accurate and sensitive detection of analytes, reducing the need for large blood samples and improving the ability to measure analytes in real-time non-invasively.
Implementation Method 1
providing, in a wearable medical diagnostic device, a first and a second optical signal transmitted from within a lumen of subsurface vasculature
Implementation Method 2
The first and second noise signals are correlated and a quotient of the unfiltered target signal and the first noise signal includes an unfiltered signal to noise ratio
Implementation Method 3
determining a filtered signal, based at least on the unfiltered target signal, the first noise signal, and the second noise signal
Data Source
AI summary
Optical measurement of physiological parameters with wearable devices often includes measuring signals in the presence of significant noise sources. These noise sources include, but are not limited to, noise associated with: variable optical coupling to skin or tissue, variations in tissue optical properties with time due to changes in humidity, temperature, hydration, variations in tissue optical properties between individuals, variable coupling of ambient light sources into detectors, and instrument and detector noise, including electrical noise, radio frequency or magnetic interference, or noise caused by mechanical movement of the detector or its components. The present disclosure includes devices and methods configured to produce representations of the raw data in which noise, broadly defined, is separated from the data of interest. The disclosed devices and methods may include subtracting or calibrating out these noise sources and other spurious fluctuations in wearable devices with optical sensors.