Optical Shunt Reduction in Medical Sensors Using Absorptive Materials
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Solution Overview
Problem
Light shunting in pulse oximetry sensors leads to errors in physiological parameter monitoring, as light passes through paths other than tissue, causing unwanted light to be detected by the photodetector.
Innovation Solution
Incorporating an optically absorptive material, such as a flat black material, between the light-emitting diodes (LEDs) and photodetectors in the sensors to absorb photons that would otherwise create unwanted light paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light paths are allowed to pass freely between LED and photodetector, then signal detection is simplified, but light shunting occurs causing measurement errors
Solution Approach 1:
An optically absorptive material is introduced as an intermediary component between the LED and photodetector. This material selectively absorbs shunted light that would otherwise create unwanted light paths, while allowing the desired light to pass through the tissue and be detected. The intermediary material thus resolves the contradiction by improving measurement precision without significantly increasing device complexity.
Solution Approach 2:
The optically absorptive material is applied locally at specific positions where light shunting occurs, such as at the edges of the bandage or in specific regions between the LED and photodetector. This localized application addresses the light shunting problem only where it occurs, rather than requiring a complete redesign of the entire sensor structure, thus improving accuracy with minimal added complexity.
2Measurement precision
If optically absorptive material is added to block shunted light, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
The patent utilizes materials with specific optical properties, particularly black or dark-colored optically absorptive materials, to block shunted light. These materials are chosen for their high light absorption characteristics across the relevant wavelength range. By leveraging the inherent optical properties of commonly available materials rather than requiring complex optical filters or coatings, the solution improves measurement precision while minimizing the increase in 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 use of optically absorptive materials significantly reduces light shunting, enhancing the accuracy of physiological parameter monitoring by minimizing errors caused by unwanted light detection.
Implementation Method 1
an optically absorptive material is provided at least partially between an LED and photodetector of the sensor
Data Source
AI summary
A patient monitoring sensor having a communication interface, through which the patient monitoring sensor can communicate with a monitor is provided. The patient monitoring sensor includes a light-emitting diode (LED) communicatively coupled to the communication interface and a detector, communicatively coupled to the communication interface, capable of detecting light. The patient monitoring sensor includes an optically absorptive material at least partially between the LED and the detector to reduce or prevent shunting of light to the detector.