Optical Sensor Thermopile Local Quality Asymmetry
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Solution Overview
Problem
Infrared sensors with thermopile-type infrared sensors have insufficient sensitivity and specific detectivity, necessitating improvements in these parameters.
Innovation Solution
The optical sensor design includes a thermoelectric conversion material portion with a strip-shaped first material layer and a second material layer, featuring a thick portion and thin portions, where the first material layer has a width of 0.1 μm or more and a thickness of 10 nm or more, with the thin portions accounting for 15% or more of the width, and a surface roughness between 1 nm and 200 nm, to reduce thermal conductance and enhance sensitivity and specific detectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thermal conductance Gth is decreased to improve sensitivity and specific detectivity, then the sensitivity and specific detectivity are improved, but the structural stability and reliability may deteriorate
Solution Approach 1:
The first material layer is designed with non-uniform thickness, featuring a thick portion (10 nm or more) at the center and thin portions at both ends. This local quality variation reduces the overall thermal conductance while maintaining structural stability at critical locations. The thick portion provides mechanical support and prevents disconnection, while the thin portions reduce heat conduction paths, thereby resolving the contradiction between improving measurement precision and maintaining reliability.
Solution Approach 2:
The first material layer employs an asymmetric thickness distribution rather than uniform thickness. The thick portion at the center and thin portions at the ends create an asymmetric structure that optimizes both thermal isolation and mechanical strength. This asymmetric design allows the layer to have low overall thermal conductance while maintaining sufficient structural integrity at the thicker regions, thus improving sensitivity without compromising reliability.
2Measurement precision
If the width of the first material layer is reduced to decrease thermal conductance, then the sensitivity is improved, but the electrical conductivity and signal output may deteriorate
Solution Approach 1:
The first material layer features local quality variation in thickness, with a thick portion at the center and thin portions at the ends. This configuration reduces the overall cross-sectional area for heat conduction, improving sensitivity, while the thick portion at the center maintains sufficient electrical conductivity for signal output. The localized thickness adjustment optimizes the balance between thermal isolation and electrical performance.
3Measurement precision
If the thickness of the first material layer is reduced to decrease thermal conductance, then the sensitivity is improved, but the mechanical strength and resistance to disconnection may deteriorate
Solution Approach 1:
The first material layer is designed with non-uniform thickness distribution, featuring a thick portion (10 nm or more) at the center and thin portions at both ends. The thick portion provides mechanical strength and resistance to disconnection, while the thin portions reduce thermal conductance. This local quality variation resolves the contradiction between improving sensitivity through thickness reduction and maintaining mechanical strength.
Solution Approach 2:
The asymmetric thickness distribution with a thick center portion and thin end portions creates an optimized structure where mechanical strength is concentrated at the center while thermal isolation is enhanced at the ends. This asymmetric design allows the layer to achieve both high sensitivity and sufficient mechanical strength simultaneously.
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 improves the sensitivity and specific detectivity of the optical sensor while minimizing the risk of disconnection and peeling, and can be further optimized by adjusting the angle and thickness ratios and using semiconductors or metals for the material layers to enhance thermal and electrical conductivity.
Implementation Method 1
a light absorbing film disposed on the thermoelectric conversion material portion to form a temperature difference in a longitudinal direction of the first material layer, the film converting received light into thermal energy
Implementation Method 2
a strip-shaped first material layer that converts thermal energy into electrical energy
Implementation Method 3
a thermoelectric conversion portion (thermopile) that converts the temperature difference (thermal energy) into electrical energy
Data Source
AI summary
An optical sensor includes a support layer, a thermoelectric conversion material portion disposed on the support layer and including a strip-shaped first material layer that converts thermal energy into electrical energy and a strip-shaped second material layer that is electrically conductive, and a light absorbing film disposed on the thermoelectric conversion material portion to form a temperature difference in a longitudinal direction of the first material layer. The first material layer includes a first region and a second region. The second material layer includes a third region and a fourth region connected to the second region. The optical sensor further includes a first electrode electrically connected to the first region, and a second electrode disposed apart from the first electrode and electrically connected to the third region. The first material layer has a width, perpendicular to the longitudinal direction, of 0.1 μm or more.