Organic Sensor Pulse Oximeters for Low-Intensity Skin-Safe Detection
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Solution Overview
Problem
Conventional pulse oximeters face issues with skin damage due to high-intensity light sources, insufficient sensitivity of photodiodes, and inflexibility, limiting their application in portable and wearable devices.
Innovation Solution
The use of a photoelectric conversion device with wavelength selectivity allows for a low-output LED, reducing skin damage and power consumption, enabling a compact, wearable pulse oximeter with organic materials and embedded near-infrared sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-intensity light source is used to compensate for insufficient photodiode sensitivity, then the optical signal quality improves, but skin burning and tissue damage occur
Solution Approach 1:
The patent applies local quality by using a photodiode with wavelength-selective sensitivity that is optimized specifically for the 760-950nm near-infrared range. This selective sensitivity allows the photodiode to efficiently detect the specific wavelengths used in pulse oximetry while maintaining high signal quality without requiring high-intensity light sources that would cause tissue damage.
Solution Approach 2:
The patent changes the operating parameters by utilizing the 760-950nm near-infrared wavelength range where hemoglobin has minimal absorption. This parameter change allows for lower light intensities to achieve sufficient signal quality, thereby preventing skin burning and tissue damage while maintaining measurement precision.
2Device complexity
If conventional photodiodes are used, then the device structure is simple, but the sensitivity is insufficient requiring high-intensity light sources
Solution Approach 1:
The patent employs a photodiode with wavelength-selective sensitivity specifically optimized for the 760-950nm range. This localized optimization of the photodiode's spectral response enhances sensitivity for pulse oximetry measurements without requiring complex multi-wavelength photodetector arrays, thus maintaining relatively simple device structure while improving measurement precision.
3Reliability
If rigid lead wires are used for connection, then the electrical connection is stable, but the sensor becomes inflexible and unsuitable for wearable applications
Solution Approach 1:
The patent replaces rigid lead wires with flexible printed circuit boards (FPCBs) that provide both mechanical flexibility and stable electrical connections. The FPCB technology allows the sensor to conform to curved body surfaces while maintaining reliable electrical connectivity, thus resolving the contradiction between connection stability and wearable flexibility.
4Volume of moving object
If the pulse oximeter is downsized for portable applications, then the portability improves, but the performance may be compromised
Solution Approach 1:
The patent utilizes the 760-950nm near-infrared wavelength range where hemoglobin absorption is minimal, allowing for effective pulse oximetry measurements with compact components. This parameter selection enables high measurement precision in a downsized device configuration, as the wavelength choice optimizes signal detection efficiency and reduces the need for large optical components.
Solution Approach 2:
The patent employs an integrated sensor design that combines the light source, wavelength-selective photodiode, and signal processing electronics into a compact composite structure. This integration maintains measurement precision while significantly reducing the overall device volume for portable and wearable applications.
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 solution enables a portable, wearable pulse oximeter that minimizes tissue damage and power consumption while maintaining performance, allowing integration into devices like smartphones and providing accurate heart rate and oxygen saturation measurements.
Implementation Method 1
a photoelectric conversion device with wavelength selectivity
Implementation Method 2
absorb a particular near infrared wavelength spectrum
Data Source
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AI summary
A pulse oximeter may include a photoelectric conversion device having wavelength selectivity so that a low output LED may be included in the pulse oximeter to prevent skin damage and to reduce power consumption. The pulse oximeter includes a light emitting device configured to emit white light and a sensor configured to detect transmitted light that is received from the light emitting device. The sensor includes a near infrared organic photoelectric conversion device configured to sense a particular near infrared wavelength spectrum of light and a red photoelectric conversion device configured to sense a particular red wavelength spectrum of light.