Miniaturized Flow Sensor Using Integrated Seebeck Thermocouple and Heating Element
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Solution Overview
Problem
Existing fluid flow measurement devices face challenges such as high costs, measurement unreliability, size limitations, and thermal inertia, making them unsuitable for widespread application, especially when measuring low fluid speeds or solid substances.
Innovation Solution
A sensor device utilizing a multi-layer printed circuit board with integrated Seebeck thermoelectric sensors and heating elements, where the heating element is embedded within the circuit board, allowing for miniaturization, reduced costs, and improved accuracy by using constantan and copper conductive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermocouple-based temperature difference sensor is used for fluid flow measurement, then measurement reliability is improved, but device complexity and manufacturing cost increase due to separate heating element assembly
Solution Approach 1:
The heating element and thermocouple are integrated into a single printed circuit board structure. The constantan conductive layer serves dual purposes as both the heating element and one leg of the thermocouple, while the copper conductive layer serves as the other leg. This merging eliminates separate assembly steps and reduces device complexity while maintaining measurement reliability.
Solution Approach 2:
The constantan conductive layer performs multiple functions simultaneously: it acts as the heating element by dissipating electrical energy as heat, and serves as one of the two conductive legs of the thermocouple for temperature sensing. This multi-functionality reduces the number of components needed and simplifies the overall device structure.
2Ease of manufacture
If traditional separate heating element assembly is used, then positioning flexibility is maintained, but manufacturing precision deteriorates due to positioning and assembly tolerances
Solution Approach 1:
The heating element and thermocouple are fabricated as integrated traces on the same printed circuit board substrate. The constantan and copper conductive layers are deposited and patterned in a multi-layer PCB manufacturing process, ensuring precise spatial relationship and thermal contact without separate assembly steps. This eliminates positioning and assembly tolerances entirely.
Solution Approach 2:
The mechanical assembly process for positioning separate heating elements and thermocouples is replaced by a PCB manufacturing process where conductive layers are deposited and patterned using photolithography and etching. This substitution of mechanical assembly with electrochemical manufacturing achieves much higher precision.
3Manufacturing precision
If a multi-layer printed circuit board with integrated heating element is used, then manufacturing precision is improved, but device complexity increases due to multi-layer structure
Solution Approach 1:
The complex multi-layer PCB structure is extracted and simplified by using only two conductive layers (constantan and copper) on a single substrate. The heating element and thermocouple functions are achieved through the interaction of these two layers rather than requiring multiple complex layers. This extraction of essential functions reduces structural complexity while maintaining manufacturing precision.
Solution Approach 2:
The device uses a homogeneous substrate material (printed circuit board) for both mechanical support and electrical conduction. The constantan and copper layers are deposited using standard PCB manufacturing techniques, creating a uniform structure that is easy to manufacture despite the multi-layer appearance. This homogeneity in material and process reduces overall device complexity.
4Measurement precision
If conventional flow sensors are used, then measurement accuracy is maintained, but device size increases making miniaturization difficult
Solution Approach 1:
The sensor transitions from a three-dimensional assembly of separate components to a two-dimensional planar structure on the printed circuit board. The heating element and thermocouple traces are arranged in flat patterns on the board surface, allowing the sensor to be miniaturized by simply reducing the trace dimensions without requiring complex three-dimensional packaging.
Solution Approach 2:
Multiple functional components (heating element, thermocouple legs, electrical connections) are merged into a single planar PCB structure. This integration dramatically reduces the overall sensor size compared to conventional sensors that require separate housings and component mounting, enabling easy miniaturization while maintaining measurement accuracy.
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 provides a cost-effective, accurate, and miniaturized sensor capable of measuring fluid flow and substance presence with reduced thermal inertia, enabling reliable and efficient detection across various applications.
Implementation Method 1
a heating element made within the multi-layer printed circuit board support in the inner conductive layer of the first conductive material
Implementation Method 2
a temperature difference sensor based on the Seebeck thermoelectric effect
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A sensor device (1) for measuring the flow of a fluid and /or the presence or the level of a substance is described, of the type comprising a support (2, 13) equipped with a sensor (10) of a temperature difference, based on the Seebeck thermoelectric effect. Advantageously, the sensor (10) is made in the support (2, 13) and it comprises a first conductive portion (3) which is made of a first conductive material on one side (2 A) of the support (2, 13) and a second conductive portion (4) which is made of a second conductive material on an opposite side (2B) of the support (2, 13), a third conductive portion (6) connecting the first and second conductive portions (3, 4) through the support (2, 13). The sensor (10) is also associated to a heating element (5) which is included in the support (2, 13).