Suspended Bolometric Micro-Plate Infrared Detector Membrane
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Solution Overview
Problem
Bolometric detectors for infrared or terahertz radiation face reduced sensitivity due to limited useful surface area, resulting from the presence of support elements and complex manufacturing processes that compromise fill factor and efficiency.
Innovation Solution
A matrix bolometric detector design featuring a membrane with alternating refractive indices, where patterns are periodically arranged to focus radiation onto micro-plates, increasing the effective refractive index gradient and concentrating incident radiation without altering the micro-plates' surface ratio, thus enhancing sensitivity without increasing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If support elements are used to suspend bolometric micro-plates above the substrate, then thermal insulation and sensitivity are improved, but the fill factor and useful surface area are reduced
Solution Approach 1:
The patent introduces a membrane structure positioned above the micro-plates that extends the detection surface in the vertical dimension. This membrane carries additional absorbent material that can capture radiation incident at oblique angles, effectively increasing the useful surface area without requiring larger micro-plates or removing the support elements.
Solution Approach 2:
The membrane structure is suspended within the existing pixel area, nesting additional detection capability inside the vertical space above the micro-plates. This nested configuration allows the membrane to contribute to radiation absorption without occupying lateral space that would reduce the fill factor.
2Productivity
If the micro-plates are miniaturized to increase pixel density, then detector resolution is improved, but the fill factor and absorption efficiency are reduced
Solution Approach 1:
By adding the membrane structure in the vertical dimension, the patent compensates for the reduced absorption cross-section of miniaturized micro-plates. The membrane provides an additional absorption surface that intercepts radiation before it reaches the substrate, maintaining overall absorption efficiency despite smaller micro-plate dimensions.
3Ease of operation
If electrical interconnection elements are added to connect absorption stage to support stage, then electrical connectivity is achieved, but manufacturing complexity and sensitivity are worsened
Solution Approach 1:
The membrane structure serves multiple functions: it provides thermal insulation, increases absorption surface area, and can be integrated with electrical interconnection elements. By combining these functions in a single structural element, the patent reduces overall device complexity while maintaining electrical connectivity.
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 solution effectively increases the useful surface area for radiation detection, optimizing sensitivity while maintaining the micro-plates' surface ratio and simplifying the manufacturing process, thereby improving detector performance without increasing costs.
Implementation Method 1
a membrane (22) substantially transparent to the radiation to be detected, having a first refractive index, arranged above each micro-plate, and in which are formed patterns, of second refractive index lower than the first refractive index
Implementation Method 2
the patterns of the membrane are periodically placed therein, along at least one predetermined axis, according to a period less than or equal to where A is a wavelength of the range of wavelengths to be detected and n is the average refractive index of the medium separating the micro-plank from the membrane
Data Source
Figure 1
Figure 2~3
Figure 4~5A
AI summary
The invention relates to a bolometric array detector for detecting electromagnetic radiation in a predetermined range of infrared or terahertz wavelengths, including a substrate (16) and an array of bolometric micro-plates (14) for detecting said radiation, suspended above the substrate by means of supporting elements (18). The detector comprises a membrane (22) arranged above each micro-plate (14), in which patterns (26) are formed that have a refraction index that is lower than that of the membrane (22). The patterns (26) are placed periodically along at least one axis of the membrane (22), with a period no higher than λ_n, in which λ is a wavelength to be detected, and n is the average refraction index of the medium separating the micro-plate (14) from the membrane (22). The width of the patterns (26) according to said axis increases from a central location of the membrane (22) towards the periphery thereof.