Implantable Optical Sensor Refractive Index Coupling
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Solution Overview
Problem
Implantable optical sensors face challenges in achieving sensitive light detection while minimizing size to reduce patient discomfort and facilitate easier implantation, with existing designs experiencing light reflections at interfaces that reduce efficiency and increase power requirements.
Innovation Solution
Incorporating an optical coupling member with a high refractive index between LEDs and the window, and between the photodetector and lens, to reduce light reflections and enhance light extraction, along with using materials like thermoset varnishes and thixotropic gels to form these members, which also provide electrical insulation in high voltage applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sensor size is reduced to minimize patient discomfort and facilitate implantation, then ease of implantation is improved, but light detection sensitivity deteriorates
Solution Approach 1:
An optical coupling member with high refractive index is introduced as an intermediary between the LED and window, and between the photodetector and lens. This coupling member mediates light transmission by reducing reflections at interfaces, thereby maintaining light detection sensitivity in a miniaturized sensor design.
Solution Approach 2:
The refractive index parameter of the optical coupling member is specifically optimized to be higher than both the LED/window and photodetector/lens interfaces. This parameter change enables effective light coupling and reduces reflection losses, allowing the sensor to maintain sensitivity despite size reduction.
2Illumination intensity
If light emission efficiency is improved by reducing reflections at interfaces, then light penetration into body tissues is enhanced, but power requirements increase
Solution Approach 1:
The optical coupling member converts the harmful effect of light reflections at interfaces into a beneficial effect. By utilizing total internal reflection principles and refractive index matching, the coupling member guides light through the window and lens with minimal losses, thereby enhancing light penetration without requiring excessive power input.
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 improves light emission efficiency, reduces sensor power requirements, increases light penetration into body tissues, and minimizes reflections, thereby enhancing the accuracy and reliability of physiological condition monitoring.
Implementation Method 1
Incorporating an optical coupling member with a high refractive index between LEDs and the window, and between the photodetector and lens, to reduce light reflections and enhance light extraction
Implementation Method 2
using materials like thermoset varnishes and thixotropic gels to form these members, which also provide electrical insulation in high voltage applications
Data Source
AI summary
An implantable optical sensor and associated manufacturing method include a sensor housing having an inner surface and an outer surface and a window formed in the housing extending between the housing inner surface and the housing outer surface. An opto-electronic device enclosed within the housing and having a photonic surface is operatively positioned proximate the window for emitting light through the window or detecting light through the window. An optical coupling member is positioned between the opto-electronic device and the window for reducing light reflection at a surface within the implantable optical sensor.