Thermoelectric Optical Sensor Film Composition for Higher Sensitivity
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Solution Overview
Problem
Existing optical sensors face challenges in achieving improved sensitivity due to high thermal conductivity of the light absorbing film, which limits the formation of a temperature difference in the thermoelectric-conversion material section.
Innovation Solution
The optical sensor incorporates a light absorbing film composed of 60-95% carbon and 5-40% resin, with a thermal conductivity of 1 W/mK or less, and an insulating film to reduce thermal conductivity and enhance insulation, allowing for large temperature differences and high light absorptance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light absorbing film with high carbon content is used, then light absorptance is improved, but thermal conductivity remains too high, reducing temperature difference formation
Solution Approach 1:
The light absorbing film is constructed as a composite material containing carbon particles (60-95 mass %) dispersed in a resin matrix (5-40 mass %). This composite structure allows the carbon to provide high light absorptance while the resin provides thermal insulation, achieving both high light absorption and low thermal conductivity simultaneously.
Solution Approach 2:
The patent optimizes the composition parameters of the light absorbing film by controlling the ratio of carbon to resin within specific ranges (60-95 mass % carbon, 5-40 mass % resin). This parameter optimization ensures the film achieves both high light absorptance and sufficiently low thermal conductivity to maintain temperature differences.
2Measurement precision
If thermal conductivity is reduced to enhance temperature difference, then sensitivity is improved, but light absorptance may be compromised
Solution Approach 1:
The composite structure of carbon particles in a resin matrix enables the light absorbing film to simultaneously achieve high light absorptance (due to carbon) and low thermal conductivity (due to resin), thereby improving sensitivity without sacrificing light absorption capability.
3Temperature
If an insulating film is added between thermoelectric material and light absorbing film, then temperature difference formation is improved, but device complexity increases
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the light absorbing film and the thermoelectric conversion material section. This intermediary layer effectively reduces thermal conduction while maintaining electrical isolation, enabling large temperature differences to form across the thermoelectric materials without significantly complicating the overall device structure.
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 configuration enables the formation of large temperature differences, thereby significantly improving the sensitivity of the optical sensor by up to 22% compared to sensors using pure carbon films.
Implementation Method 1
a light receiving portion (light absorbing film) that is configured to convert optical energy into thermal energy
Implementation Method 2
a thermoelectric conversion section (thermopile) that is configured to convert thermal energy into electric energy
Data Source
AI summary
An optical sensor includes a support layer, a thermoelectric-conversion material section disposed on the support layer and including strip-shaped p-type material layers configured to convert thermal energy into electric energy and strip-shaped n-type material lavers configured to convert thermal energy into electric energy, a heat sink, a light absorbing film, and an insulating film disposed between the thermoelectric-conversion material section and the light absorbing film. Each of the p-type material layers includes a first region overlapping the heat sink and a second region overlapping the light absorbing film. Each of the n-type material layers includes a third region overlapping the heat sink and a fourth region overlapping the light absorbing film. The p-type material layers and the n-type material layers are alternately disposed in series. The light absorbing film includes 60 mass % to 95 mass % of carbon and 5 mass % to 40 mass % of a resin.