Strain Gauge Thermal Layers to Limit Resistor Self-Heating
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Solution Overview
Problem
Strain gauges using chromium or nickel resistors suffer from self-heating due to current flow, leading to reduced measurement accuracy.
Innovation Solution
A strain gauge design featuring a flexible substrate with a resistor made of chromium or nickel, a functional layer with higher thermal conductivity between the substrate and resistor, and a metallic layer with higher thermal conductivity laminated on folded portions of the resistor, to dissipate heat and maintain measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current flows into the resistor to operate the strain gauge, then the strain gauge can detect strain, but self-heating is generated by the resistor which reduces measurement accuracy
Solution Approach 1:
The patent introduces a heat dissipation layer as an intermediary component between the resistor and the insulating layer. This heat dissipation layer acts as a thermal mediator that conducts heat away from the resistor, preventing self-heating while allowing the resistor to function normally for strain detection
Solution Approach 2:
The patent changes the thermal conductivity parameter by introducing materials with high thermal conductivity (such as metal particles or conductive compounds) into the heat dissipation layer. This parameter change enables effective heat transfer from the resistor, reducing self-heating effects while maintaining electrical insulation
2Measurement precision
If a heat dissipation layer is added to reduce self-heating, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The heat dissipation layer is designed to serve multiple functions simultaneously: it provides thermal conduction to reduce self-heating, maintains electrical insulation to prevent short circuits, and can also serve as a structural support layer. This multi-functionality reduces the need for additional separate components
Solution Approach 2:
The patent employs composite materials for the heat dissipation layer, combining materials with high thermal conductivity and high electrical resistivity in a single integrated layer. This composite approach allows one layer to fulfill both thermal and electrical requirements, simplifying the overall device structure
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 design effectively dissipates heat generated by the resistor, improving measurement accuracy and reducing sensitivity loss, while also enhancing adhesion and preventing oxidation.
Implementation Method 1
a functional layer formed of an insulating material that has a higher thermal conductivity than the resistor, the functional layer being situated between the substrate and the resistor. A first metallic layer formed of a material that has a higher thermal conductivity than the resistor is laminated on the folded portions
Implementation Method 2
the current flows into the resistor and thus self-heating is generated by the resistor
Data Source
AI summary
A strain gauge includes a flexible substrate and a resistor formed of material including at least one of chromium or nickel, the resistor being situated above the substrate. The strain gauge includes a functional layer formed of an insulating material that has a higher thermal conductivity than the resistor, the functional layer being situated between the substrate and the resistor. The resistor includes multiple resistive patterns that are juxtaposed. The resistor includes folded portions each of which connects end portions of resistive portions that are next to each other. A first metallic layer formed of a material that has a higher thermal conductivity than the resistor is laminated on the folded portions.