Erbium-Doped Glass Optical Amplification for Low-Power PPG
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Solution Overview
Problem
Existing photoplethysmography (PPG) techniques face inefficiencies in power consumption and wavelength suitability for accurate heart rate and oxygen saturation measurements, particularly with green and infrared LEDs.
Innovation Solution
Employing erbium doped glass as an optical amplifier to enhance light transmission and conversion, utilizing photoluminescence to generate higher intensity wavelengths suitable for PPG, such as green and red light, thereby reducing power requirements and improving measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If green LED is used to detect heartbeat, then pulsatile signal intensity is improved, but power consumption increases
Solution Approach 1:
The patent introduces an optical amplifier as an intermediary component between the light source and the photodetector. This amplifier uses erbium-doped glass to convert infrared light (from an energy-efficient IR LED) into visible light through photoluminescence, thereby providing the necessary signal intensity for accurate PPG measurements while using a lower-power light source
Solution Approach 2:
The patent changes the wavelength parameter of the light by using an optical amplifier that converts infrared wavelength (940 nm) to visible wavelength (500-650 nm). This allows the system to use infrared LEDs which consume less power while still achieving the required signal intensity for heartbeat detection
2Use of energy by moving object
If infrared LED is used to detect heartbeat during sleep, then power consumption is reduced, but wavelength suitability for accurate measurement deteriorates
Solution Approach 1:
The optical amplifier serves as a mediator that converts the infrared light from the low-power LED into visible light with appropriate wavelength for accurate PPG measurements. The erbium-doped glass amplifies the infrared signal and transforms it to the optimal wavelength range (500-650 nm) for detecting blood volume changes
Solution Approach 2:
The system changes the output wavelength parameter from infrared (940 nm) to visible light (500-650 nm) through the optical amplifier. This wavelength transformation enables the use of low-power infrared LEDs while maintaining measurement accuracy suitable for applications like sleep monitoring
3Measurement precision
If red LED is used to detect oxygen saturation, then measurement capability is improved, but power consumption increases
Solution Approach 1:
The optical amplifier acts as an intermediary that enables the use of lower-power light sources by amplifying the light signal. This allows the system to detect oxygen saturation using less power-intensive LEDs while maintaining the necessary signal strength for accurate measurements
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 erbium doped glass amplifies light intensity, enhancing the efficiency and reliability of PPG measurements by optimizing power consumption and improving the sensitivity of heart rate and oxygen saturation detection.
Implementation Method 1
an amplification layer further comprising a doped rare earth metal and with a first side and a second side, the amplification layer configured to receive light of the first wavelength and first intensity and transmit light of a second wavelength with a second intensity
Data Source
AI summary
A user device for monitoring a physical condition of a user, such as a heart rate or blood oxygen level, includes an erbium doped glass component and a light source. The light source is configured to generate light equal to an excitation frequency of the erbium doped glass. The erbium doped glass component is configured to generate, through photoluminescence, one or more peaks of higher intensity light corresponding to a wavelength which can be used to monitor a physical condition of a user. The amplified light is sent to the user and received back at a photodetector, which can then algorithmically determine a physical condition of a user.