Dual-Sided Strain Gauge Resolving Temperature-Induced Voltage Errors
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Solution Overview
Problem
Conventional strain gauge sensors fail to differentiate between touches with and without physical force at extreme temperatures, as temperature differences cause misleading voltage differentials, rendering them nonfunctional for detecting physical touches outside normal operating ranges.
Innovation Solution
A dual-sided strain gauge design featuring two Wheatstone bridges within a flexible printed circuit board, where resistors are positioned to span across substrates on both top and bottom surfaces, allowing for differential voltage measurement between the bridges to distinguish between force applied and temperature-induced changes, ensuring accurate force detection across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single Wheatstone bridge strain gauge is used, then the device structure is simple, but the sensor cannot differentiate between touches with and without physical force at extreme temperatures
Solution Approach 1:
The single Wheatstone bridge is segmented into two separate Wheatstone bridges positioned on opposite sides of the substrate. Each bridge independently measures strain, allowing the system to differentiate between temperature-induced strain and force-induced strain by comparing the differential readings between the two bridges.
Solution Approach 2:
The solution transitions from a single-plane measurement to a dual-sided three-dimensional arrangement. By placing Wheatstone bridges on both the front and back surfaces of the substrate, the system adds a spatial dimension to the measurement, enabling temperature compensation through differential comparison of readings from opposite sides.
2Measurement precision
If resistors are positioned to span across substrates in a dual-sided configuration, then temperature-induced voltage differentials are minimized, but the manufacturing complexity increases
Solution Approach 1:
Resistors are strategically positioned in specific locations on the substrate surface with different orientations. Some resistors span across the substrate while others are positioned locally on specific surfaces, creating local quality variations that enable differential measurement of strain versus temperature effects.
Solution Approach 2:
The resistor configuration employs asymmetric positioning where resistors on opposite sides of the substrate are arranged differently. This asymmetric layout ensures that temperature-induced strain affects both bridges equally while force application creates differential readings, improving measurement precision despite increased manufacturing complexity.
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
Enables reliable differentiation between touches with and without physical force even at extreme temperatures by minimizing the impact of temperature-induced voltage differentials, maintaining the sensor's functionality and accuracy across a broader temperature range.
Implementation Method 1
the strain on the resistors R1 and R2 changes with respect to the strain on the resistors R3 and R4. The result is a change of the resistance of the resistors R1 and R2 with respect to the resistance of the resistance of the resistors R3 and R3
Implementation Method 2
the FPCB 5 is deformed so that the strain on the resistors R1 and R2 changes with respect to the strain on the resistors R3 and R4
Data Source
AI summary
A strain gauge includes first and second substrates spaced apart from one another. A first flexible printed circuit board portion is in contact with a top side of the first and second substrates, and has a first Wheatstone bridge formed therein. The first flexible printed circuit board portion positions the first Wheatstone bridge such that two resistors of the first Wheatstone bridge are positioned to span from the top side of the first substrate to the top side of the second substrate. A second flexible printed circuit board portion is in contact with a bottom side of the first and second substrates, and has a second Wheatstone bridge formed therein. The second flexible printed circuit board positions the second Wheatstone bridge such that two resistors of the second Wheatstone bridge are positioned to span from the bottom side of the first substrate to the bottom side of the second substrate.