Flexible Strain Gauge Stabilizing TCR via Grain Control
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Solution Overview
Problem
Strain gauges with flexible substrates face instability in gauge characteristics, particularly in the temperature coefficient of resistance (TCR), making them unreliable for precise measurements.
Innovation Solution
Incorporating a substance that controls the growth of crystal grains in the resistor, such as TiN or AlN, into the strain gauge's Cr composite film to stabilize the TCR, ensuring it remains within a favorable range of -1000 ppm/°C to +1000 ppm/°C, thereby improving the gauge's stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate is used for the strain gauge, then the strain gauge can be attached to curved or flexible objects, but the temperature coefficient of resistance TCR becomes unstable and gauge characteristics lack stability
Solution Approach 1:
The invention changes the chemical composition parameters of the resistor material by adding specific substances (such as tungsten, molybdenum, or their alloys) to the chromium-based resistor material. This parameter change stabilizes the TCR while maintaining the flexibility of the substrate, resolving the contradiction between adaptability and reliability.
Solution Approach 2:
The invention creates a composite resistor material by combining chromium with other metals (tungsten, molybdenum, or their alloys) in specific proportions. This composite material structure provides both the flexibility needed for flexible substrates and the stable TCR characteristics required for reliable measurement, simultaneously addressing both requirements.
2Quantity of substance
If chromium or nickel materials are used for the resistor, then the resistor can be formed with good conductivity, but the TCR stability deteriorates when used on flexible substrates
Solution Approach 1:
The invention forms a composite material system by combining chromium (or nickel) with tungsten, molybdenum, or their alloys in specific ratios. This composite structure maintains the good electrical conductivity of the base material while the added elements stabilize the TCR, resolving the contradiction between conductivity and TCR stability.
Solution Approach 2:
The invention introduces specific alloying elements (tungsten, molybdenum) in controlled amounts to locally modify the properties of the chromium or nickel matrix. This local quality enhancement stabilizes the TCR in specific regions of the resistor material without compromising the overall electrical conductivity.
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 addition of these substances effectively stabilizes the TCR, enhancing the strain gauge's reliability and maintaining its electrical properties before and after heating, thus improving the overall stability and accuracy of the gauge characteristics.
Implementation Method 1
a first substance having a function of controlling growth of crystal grains as the main component of the resistor, is added to the resistor
Data Source
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AI summary
The present strain gauge includes a substrate having flexibility; and a resistor formed from a material containing at least one of chromium and nickel, on the substrate, wherein a first substance having a function of controlling growth of crystal grains as the main component of the resistor, is added to the resistor.