Optical Blood Flow Measurement Using Long-Wavelength DCS
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Solution Overview
Problem
Current diffuse correlation spectroscopy (DCS) systems face limitations in measuring cerebral blood flow in adults due to limited depth penetration and extra-cerebral contamination, which hampers their adoption in healthcare settings.
Innovation Solution
The use of longer-wavelength infrared light (at or above 1000 nm) for DCS measurements, combined with near-infrared spectroscopy (NIRS) systems, enhances signal penetration and sensitivity, allowing for more reliable blood flow measurements without the need for wavelength filters, thereby simplifying and increasing the efficiency of the combined system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If shorter IR wavelengths (650-900 nm) are used for DCS measurements, then hemoglobin absorption sensitivity is improved, but depth penetration is limited and extra-cerebral contamination increases
Solution Approach 1:
The patent changes the wavelength parameter from the conventional 650-900 nm range to longer wavelengths (1000-1400 nm or 1700 nm), fundamentally altering the optical interaction properties to achieve both deeper penetration and maintained measurement precision through the new wavelength characteristics
2Length of stationary object
If longer IR wavelengths (at or above 1000 nm) are used for DCS measurements, then depth penetration and signal-to-noise ratio are improved, but hemoglobin absorption sensitivity may be reduced
Solution Approach 1:
The patent exploits the parameter change of wavelength to access a new operational regime where longer wavelengths provide both deep penetration and adequate hemoglobin sensitivity through the unique optical properties of the 1000-1400 nm and 1700 nm regions
Solution Approach 2:
The patent transitions to a different wavelength dimension (beyond the conventional near-IR window) to simultaneously achieve deep tissue penetration and maintain measurement precision, effectively adding a new dimension to the optical measurement approach
3Measurement precision
If combined DCS and NIRS systems use wavelength filters to block illumination from the other modality, then measurement accuracy is improved, but device complexity and efficiency are reduced
Solution Approach 1:
The patent extracts and removes the wavelength filter component from the combined system by operating DCS and NIRS in non-overlapping wavelength regions, eliminating the need for filtering while maintaining measurement accuracy
Solution Approach 2:
The patent separates the DCS and NIRS operations into different wavelength dimensions (DCS at 1000-1400 nm or 1700 nm, NIRS at 650-900 nm), allowing both modalities to operate simultaneously without interference and without requiring filtering components
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
This approach provides a stronger signal and higher efficiency in measuring brain blood flow and deeper tissue parameters, improving the signal-to-noise ratio and reducing contamination from superficial tissues, thus overcoming the limitations of existing DCS systems.
Implementation Method 1
a light source optically coupled to the probe, the light source directing light of at least 1000 nm into the tissue
Implementation Method 2
a detector optically coupled to the probe, the detector to detect light based on scattering of light from the light source in the tissue
Data Source
AI summary
An apparatus, including: a probe to interface with a surface of a tissue; a light source optically coupled to the probe, the light source directing light of at least 1000 nm into the tissue; a detector optically coupled to the probe, the detector to detect light based on scattering of light from the light source in the tissue, and the detector having a light sensitivity in a range of at least 1000 nm; a processor coupled to the detector, the processor to: receive a signal from the detector corresponding to the detected light from the light source, and determine a blood flow measurement from the region of interest using diffuse correlation spectroscopy based on the signal.