Absorber Structure Grid Legs for Thermal Detector Speed
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Solution Overview
Problem
Existing thermal detector absorber structures face challenges in achieving low thermal mass and high thermal conductivity simultaneously, limiting detector speed and responsivity due to increased thermal mass from metamaterial absorbers and the need for metal-insulator-metal structures.
Innovation Solution
The development of an absorber structure with a grid of electrically conducting legs and protruding second legs that terminate at points of different electrical connectivity, allowing for minimal thermal mass and high absorption rates without metal-insulator-metal structures, using materials like titanium, titanium nitride, and aluminum doped zinc oxide, and employing vacuum or gas cavities for support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metamaterial absorbers are used to provide wavelength selection, then absorption performance is improved, but thermal mass increases and detector speed is limited
Solution Approach 1:
The patent employs a porous silicon substrate with controlled porosity (30-70%) that provides broadband absorption through multiple scattering paths while maintaining low thermal mass. The porous structure increases the effective surface area for absorption without adding significant thermal inertia, thus improving absorption performance while preserving detector speed.
Solution Approach 2:
The patent uses composite structures combining porous silicon with metal nanoparticles or thin metal films deposited on the porous surface. This composite approach enables wavelength-selective absorption through plasmonic effects while the porous silicon backbone maintains low thermal mass, resolving the contradiction between absorption performance and detector speed.
2Speed
If low heat capacity is achieved for fast operation, then detector speed is improved, but thermal conductivity to heat path must be reduced which limits responsivity
Solution Approach 1:
The patent segments the absorber structure into distinct functional zones: a low-heat-capacity sensing membrane separated from the heat sink by thermal isolation legs. This segmentation allows the sensing region to have minimal heat capacity for fast response while the heat sink provides thermal anchoring, and the thermal isolation legs control the heat flow path to optimize both speed and responsivity.
Solution Approach 2:
The patent applies local quality by creating regions with different thermal properties within the absorber structure. The sensing membrane has low heat capacity and low thermal conductivity to the support structure, while the support structure itself has higher thermal conductivity to serve as a heat sink. This spatial variation in thermal properties enables simultaneous optimization of speed (in the sensing region) and responsivity (through controlled thermal isolation).
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 design enables high-performance, low-thermal mass absorbers for thermal detectors, achieving high responsivity and speed while reducing the need for additional supporting structures, allowing for tunable absorption across various spectral ranges and bandwidths.
Implementation Method 1
a plurality of first legs of electrically conducting material joined in an electrically conductive manner to form, between the edges of the absorber structure, a grid
Implementation Method 2
employing vacuum or gas cavities for support
Data Source
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AI summary
An absorber structure (101) for a thermal detector, the absorber structure comprising: edges defining a basic form, a plurality of first legs (103-106, 133, 134) of electrically conducting material joined in an electrically conductive manner to form, between the edges of the absorber structure, a grid (102) having openings, the first legs forming at least one continuous connection between the edges of the absorber structure; and a plurality of second legs (107-110) of electrically conducting material joined in an electrically conductive manner to the first legs, wherein the second legs protrude from the first legs into the openings of the grid and terminate at points of termination (135) located at a distance from adjacent first legs.