Integrated Thermopile Sensor With Vertical Air-Suspended Thermocouples

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Solution Overview

Problem

Existing thermopile technologies face inefficiencies due to the use of non-standard materials and complex processing steps, leading to noise, low sensitivity, and high costs, making them unsuitable for portable devices.

Innovation Solution

A thermopile design using standard semiconductor materials and processes, with a vertical structure of thermocouples surrounded by air and housed in a hermetically sealed silicon enclosure, allowing for efficient thermal conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If non-standard materials and complex processing steps are used to manufacture thermopiles, then conversion efficiency can be improved, but manufacturing cost and device complexity increase

Engineering Contradiction:
Improveconversion efficiencyVSAvoidmanufacturing process complexity
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent changes the structural parameters of thermocouples from horizontal to vertical configuration, and modifies the thermal environment parameters by introducing air suspension and vacuum sealing. These parameter changes enable standard semiconductor materials to achieve high conversion efficiency without complex processing steps.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a vacuum environment (inert atmosphere) by sealing the thermopile structure, which eliminates thermal conduction through air molecules. This inert environment reduces thermal loss and improves conversion efficiency while using standard materials and processes.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

2Use of energy by moving object

If non-standard materials and complex processing steps are used to manufacture thermopiles, then conversion efficiency can be improved, but manufacturing cost increases

Engineering Contradiction:
Improveconversion efficiencyVSAvoidmanufacturing cost
Core Design Contradiction:
Use of energy by moving objectVSEase of manufacture

Solution Approach 1:

The patent makes the thermopile structure universal by using standard semiconductor materials and processes that are already widely available in the industry. The vertical thermocouple design with air suspension can be manufactured using existing CMOS or bipolar technology, making the solution universally applicable and cost-effective.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

By changing the structural parameters to vertical configuration and modifying the thermal environment through vacuum sealing, the patent achieves high conversion efficiency using standard materials, thereby reducing manufacturing cost while maintaining high performance.

Inventive Principle:
Principle #35Parameter changes

3Volume of moving object

If horizontal thermocouples are formed in thin film on rigid substrates, then device size is reduced, but sensitivity decreases and noise increases

Engineering Contradiction:
Improvedevice sizeVSAvoidsensitivity
Core Design Contradiction:
Volume of moving objectVSMeasurement precision

Solution Approach 1:

The patent transitions from horizontal thermocouple configuration to vertical configuration, utilizing the third dimension (height) instead of extending in the planar direction. This dimensional change maintains compact device footprint while improving sensitivity by enabling better thermal isolation and reduced heat loss through the substrate.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

By sealing the vertical thermocouple structure in a vacuum environment, the patent eliminates thermal conduction through air, creating an inert thermal environment. This significantly reduces noise and improves sensitivity while maintaining the compact size advantage.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

4Ease of manufacture

If thermocouples are arranged in vertical structure in plastic substrate, then manufacturing is simplified, but thermal conversion efficiency decreases

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidthermal conversion efficiency
Core Design Contradiction:
Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent introduces vacuum sealing to create an inert thermal environment around the vertical thermocouples. This eliminates thermal conduction through air and reduces heat loss, significantly improving thermal conversion efficiency while maintaining the manufacturing simplicity of the vertical structure.

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

Solution Approach 2:

The patent uses air suspension (pneumatic isolation) to thermally isolate the vertical thermocouples from the substrate. By suspending the thermocouples in air and sealing the environment, the system achieves high thermal conversion efficiency through reduced thermal conduction while keeping the manufacturing process simple.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 achieves high sensitivity, low noise, and low manufacturing costs, enabling applications in portable devices with improved efficiency and reduced thermal dispersion.

Implementation Method 1

Each thermocouple is formed by portions of dissimilar materials and generates a voltage when the junctions are exposed to different temperatures... according to the Seebeck equation

Methodology Applied
Scientific EffectSeebeck effect: Seebeck Effect

Data Source

PatentEP4155696B1Integrated thermal sensor and manufacturing process thereof
Publication Date: 2025.10.29 STMICROELECTRONICS SRL
  • EP4155696B1 patent drawingFigure 1~3
  • EP4155696B1 patent drawingFigure 4~5
  • EP4155696B1 patent drawingFigure 6A~6B

AI summary

Integrated thermal sensor having a housing (21) delimiting an internal space (26). A support region (30) extends through the internal space; a plurality of thermocouple elements (31) are carried by the support region (30) and are electrically coupled to each other. Each thermocouple element (31) is formed by a first and a second thermoelectrically active region (34, 35) of a first and, respectively, a second thermoelectrically active material, the first thermoelectrically active material having a first Seeback coefficient, the second thermoelectrically active material having a second Seeback coefficient, other than the first Seeback coefficient. At least one of the first and second thermoelectrically active regions (34, 35) is a silicon-based material. The first and second thermoelectrically active regions (34, 35) of each thermocouple element (31) are formed by respective elongated regions extending at a mutual distance into the internal space (26) of the housing (21), from and transversely to the support region (300).