Thermopile Photosensor Layout for Higher Infrared Detectivity
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Solution Overview
Problem
Existing thermopile infrared sensors have insufficient specific detectivity, which limits their performance in converting light energy into electrical energy effectively.
Innovation Solution
A photosensor design featuring a thermoelectric conversion material section with alternating p-type and n-type material layers, a heat sink, and a light-absorbing film to create temperature differences, optimizing the placement of material layers to maximize the temperature gradient and reduce electrical and thermal resistance, thereby enhancing the signal-to-noise ratio and specific detectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional thermopile infrared sensor design is used, then the structure is simple, but the specific detectivity is insufficient
Solution Approach 1:
The thermoelectric conversion material section is divided into multiple first material layers and second material layers arranged alternately. Each layer is segmented into different regions (first region, second region, third region, fourth region) with specific functions, creating a multi-layered structure that enhances temperature gradient utilization and improves specific detectivity while maintaining manageable complexity through modular design
Solution Approach 2:
Different regions of the material layers are optimized for specific functions: the first region and third region are positioned to maximize temperature gradient exposure, while the second and fourth regions are configured for electrical connection. The light-absorbing film is selectively disposed in specific regions to concentrate thermal energy where most needed, creating local quality variations that enhance overall performance
2Measurement precision
If the material layers are arranged to maximize temperature gradient, then the specific detectivity improves, but the electrical resistance increases
Solution Approach 1:
The thermoelectric material is segmented into alternating first and second material layers, each with optimized thickness and arrangement. This segmentation allows the structure to achieve both high temperature gradient utilization (for detectivity) and controlled electrical resistance by optimizing the number and thickness of individual layers
Solution Approach 2:
The first and second material layers are merged into an integrated alternating structure where thermal and electrical paths are optimally combined. The alternating arrangement creates efficient thermal coupling while maintaining electrical isolation where needed, achieving a balance between temperature gradient utilization and electrical resistance management
3Temperature
If the first region is disposed between the light-absorbing film and heat sink, then the temperature gradient is maximized, but the manufacturing precision requirements increase
Solution Approach 1:
The light-absorbing film is pre-positioned in specific regions before the thermoelectric material layers are deposited. This preliminary positioning ensures that the first region of the material layers will naturally form in the optimal location for temperature gradient utilization, reducing the need for post-manufacturing adjustments and lowering precision requirements
Solution Approach 2:
The material layers are deposited with different local properties: the first and third regions are optimized for thermal exposure with higher light-absorbing film coverage, while the second and fourth regions are optimized for electrical connection with different material composition or thickness. This local quality differentiation allows each region to be manufactured with appropriate precision tolerances
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 design significantly improves the specific detectivity of the photosensor by increasing the signal-to-noise ratio, allowing for more efficient conversion of light energy into electrical energy, leading to enhanced performance in detecting infrared radiation.
Implementation Method 1
a light-absorbing film that is disposed in a region surrounded by inner edges of the heat sink as viewed in a thickness direction of the support so as to form temperature differences on the first main surface of the support in longitudinal directions of the first material layers, the light-absorbing film being configured to convert received light into thermal energy
Implementation Method 2
a thermoelectric conversion material section that is disposed on a first main surface of the support and that includes a plurality of first material layers each having an elongated shape and a plurality of second material layers each having electrical conductivity and an elongated shape, the first material layers and the second material layers each being configured to convert thermal energy into electrical energy
Implementation Method 3
a heat sink that is disposed on a second main surface of the support and along an outer edge of the support
Data Source
AI summary
A photosensor includes: a support; a thermoelectric conversion material section that is disposed on a first main surface of the support and that includes a plurality of first material layers each having an elongated shape, a plurality of second material layers each having electrical conductivity and an elongated shape, and an insulating film, the first material layers and the second material layers each being configured to convert thermal energy into electrical energy; a heat sink that is disposed on a second main surface of the support and along an outer edge of the support; a light-absorbing film that is disposed in a region surrounded by inner edges of the heat sink as viewed in a thickness direction of the support so as to form temperature differences on the first main surface of the support in longitudinal directions of the first material layers.