Thermographic sensor with thermo-couples on a suspended grid and processing circuits in frames thereof
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Solution Overview
Problem
Conventional thermographic sensors face challenges in miniaturization due to vacuum-sealed structures that limit sensitivity and are prone to thermal cross-talk, affecting their accuracy and size constraints for various applications.
Innovation Solution
The thermographic sensor integrates thermo-couples on a semiconductor on insulator body with a suspended grid structure, where each sensing element has a thermally insulated hot and cold joint, and includes a processing circuit for improved signal amplification and reduced thermal conduction, enhancing sensitivity and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a vacuum-sealed structure is used to thermally insulate the membrane, then thermal insulation is improved, but device complexity and size increase
Solution Approach 1:
The patent extracts the vacuum-sealed structure from the design and replaces it with a thermally insulating layer formed directly on the substrate. This eliminates the need for complex vacuum sealing while maintaining thermal insulation functionality, thereby reducing device complexity and size.
Solution Approach 2:
The patent introduces a thermally insulating layer as an intermediary between the substrate and the membrane. This layer provides the necessary thermal insulation without requiring vacuum sealing, thus simplifying the overall device structure while maintaining temperature control.
2Device complexity
If a single suspended membrane is used for all thermo-couples, then device complexity is reduced, but thermal cross-talk increases
Solution Approach 1:
The patent segments the membrane structure by providing individual thermal insulation for each thermo-couple's hot joint through the thermally insulating layer. This segmentation prevents thermal cross-talk between adjacent thermo-couples while maintaining a relatively simple overall structure without requiring multiple separate membranes.
3Temperature
If deep etching process is used to release each membrane, then thermal insulation is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges the thermal insulation function with the substrate structure itself by forming a thermally insulating layer on the substrate. This eliminates the need for deep etching processes to create isolated membranes, as the insulation is provided by the layer rather than by physical separation, thereby simplifying manufacturing.
4Quantity of substance
If thermo-couples are formed with cold joints on bulk die, then thermal conduction is improved, but thermal cross-talk increases
Solution Approach 1:
The patent applies local quality by providing thermal insulation specifically at the hot joint locations of each thermo-couple through the thermally insulating layer. This allows thermal conduction to occur where needed (at cold joints on the bulk die) while preventing thermal cross-talk at the hot joints through localized insulation.
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 achieves improved thermal insulation, reduced thermal cross-talk, and increased sensitivity, allowing for a more compact thermographic sensor suitable for diverse applications, including consumer devices, while maintaining high accuracy.
Implementation Method 1
Each thermo-couple converts a temperature gradient between a hot and a cold junction (generated by the thermal radiation) into electrical energy (measuring its amplitude) according to the Seebeck effect
Implementation Method 2
The frames comprise one or more conductive layers of thermally conductive material for thermally equalizing the cold joints with the substrate
Data Source
AI summary
A thermographic sensor is proposed. The thermographic sensor includes a plurality of sensing elements each comprising at least one thermo-couple. The thermographic sensor is integrated on a semiconductor on insulator body that is patterned to define a grid suspended from a substrate; for each sensing element, the grid has a frame with the cold joint of the thermo-couple, a plate with the hot joint of the thermo-couple and one or more arms sustaining the plate from the frame. The frames include one or more conductive layers of thermally conductive material for thermally equalizing the cold joints with the substrate. Moreover, each sensing element may also include a processing circuit for the thermo-couple that is integrated on the corresponding frame. A thermographic device including the thermographic sensor and a corresponding signal processing circuit, and a system including one or more thermographic devices are also proposed.