Cyanotic Infant Sensor with Light-Absorbing Surface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Accurate and consistent pulse oximetry measurements are difficult to obtain in cyanotic infants due to variations in tissue structure that alter the mean pathlength ratio of red to infrared light, differing from normal infants.
Innovation Solution
A cyanotic infant sensor is designed to limit variations in the mean pathlength ratio by matching the wavelengths and intensities of red and infrared LEDs and detectors, and using a light-absorbing surface and restricted detector field-of-view to compensate for these variations, allowing for accurate calibration and measurement of oxygen saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pulse oximetry is used on cyanotic infants, then oxygen saturation measurement is performed, but measurement accuracy deteriorates due to variations in tissue structure altering the mean pathlength ratio
Solution Approach 1:
The patent applies local quality by making the detector sensitive primarily to a specific region directly beneath it through the use of a light-absorbing surface and restricted field-of-view optics. This creates a localized measurement zone that reduces sensitivity to variations in tissue structure beyond that region, thereby improving measurement accuracy in cyanotic infants with abnormal tissue tone while maintaining the ability to perform oxygen saturation measurements.
Solution Approach 2:
The patent changes the optical parameters by using a light-absorbing surface material with specific absorption characteristics and configuring the detector field-of-view to specific angular limits. These parameter changes create a more controlled light path that is less sensitive to variations in mean pathlength ratio caused by different tissue structures, resolving the contradiction between measurement accuracy and adaptability.
2Measurement precision
If the detector field-of-view is restricted and light-absorbing surface is used, then mean pathlength ratio variations are limited, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into the light-absorbing surface component: it serves as both the mounting surface for the detector and the optical element that defines the field-of-view and absorbs scattered light. This integration achieves the goal of limiting mean pathlength ratio variations while avoiding the complexity of adding separate components for each function.
Solution Approach 2:
The light-absorbing surface is designed to perform multiple functions simultaneously: structural support for the detector, optical absorption for scattered light, and field-of-view definition through its geometric configuration. This multi-functionality achieves measurement consistency without increasing device 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 sensor increases the accuracy and consistency of pulse oximetry measurements by minimizing the impact of tissue structure differences, providing reliable oxygen saturation readings in cyanotic infants.
Implementation Method 1
The sensor has a light-absorbing surface that limits variations in a ratio of mean pathlengths
Implementation Method 2
The detector 130 is positioned so as to detect the emitted light as it emerges from the tissue site
Implementation Method 3
The Beer-Lambert law states that the concentration ci of an absorbent in solution can be determined by the intensity of light transmitted through the solution
Data Source
AI summary
A pulse oximetry sensor comprises emitters configured to transmit light having a plurality of wavelengths into a fleshy medium. A detector is responsive to the emitted light after absorption by constituents of pulsatile blood flowing within the medium so as to generate intensity signals. A sensor head has a light absorbing surface adapted to be disposed proximate the medium. The emitters and the detector are disposed proximate the sensor head. A detector window is defined by the sensor head and configured so as to limit the field-of-view of the detector.