Time-Resolved Optical Measurement for Blood Oxygenation Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional pulse oximeters are susceptible to errors in blood oxygenation level readings due to physiological variables, particularly skin color, as they rely on relative measurements rather than absolute optical properties.
Innovation Solution
An optical measurement device employing time-resolved techniques to determine absolute coefficients of absorption and reduced scattering in tissue, using a light source, detector, and processing unit to generate histogram data and calculate absolute blood oxygenation levels based on the Beer-Lambert Law, providing more accurate and less error-prone readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse oximeters use relative measurements with two or more wavelengths, then the device complexity is reduced and ease of manufacture is improved, but measurement precision deteriorates due to susceptibility to physiological variables and skin color
Solution Approach 1:
The patent changes the measurement parameter from relative absorption ratios to absolute optical properties (absorption coefficient and reduced scattering coefficient) by introducing time-resolved photon detection. This allows determination of blood oxygenation levels independent of skin color and physiological variables, directly improving measurement precision without requiring complex calibration procedures
Solution Approach 2:
The patent adds the time dimension to optical measurements by detecting photon arrival times and generating temporal point spread functions. This time-resolved approach provides additional information about tissue optical properties that enables more accurate blood oxygenation measurement while maintaining relatively simple device architecture
2Reliability
If conventional pulse oximeters rely on relative measurements, then the device complexity is minimized, but reliability deteriorates due to errors from skin color and calibration issues
Solution Approach 1:
The patent transforms the measurement from relative to absolute by determining actual absorption and scattering coefficients. This eliminates dependence on calibration and skin color, significantly improving reliability and consistency of readings across different users and conditions
Solution Approach 2:
The patent replaces the conventional continuous-wave measurement system with a time-resolved photon detection system. This substitution enables separation of photons based on their travel time through tissue, providing more reliable measurements of tissue optical properties without requiring complex mechanical adjustment mechanisms
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 allows for high-resolution measurements of blood oxygenation, heart rate, respiratory rate, and other characteristics with improved accuracy, reducing errors associated with skin color and calibration issues in conventional systems.
Implementation Method 1
detect arrival times for photons of the light pulses after the photons are scattered by the target
Implementation Method 2
a detector configured to detect arrival times for photons of the light pulses
Implementation Method 3
calculate absolute blood oxygenation levels based on the Beer-Lambert Law
Data Source
AI summary
An illustrative optical measurement device includes a light source configured to emit light pulses directed at a target. The optical measurement device further includes a detector configured to detect arrival times for photons of the light pulses after the photons are scattered by the target. The optical measurement device further includes a processing unit configured to generate, based on the arrival times of the photons at the detector, histogram data associated with the target. The processing unit is further configured to determine, based on the histogram data, an absolute optical property associated with the target. The processing unit is further configured to determine, based on the absolute optical property, a blood oxygenation level of the user, and perform an operation based on the blood oxygenation level.