Fluidic Piezoresistive Strain Gauge for Large Displacement
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Solution Overview
Problem
Traditional strain gauges are limited in measuring high displacement, particularly in biomedical applications where large tissue deformation needs to be accurately recorded.
Innovation Solution
A fluidic strain gauge utilizing a glycerin/aqueous salt mixture within a polymer casing, which changes electrical impedance in response to strain, allowing for high displacement measurement through impedance analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional electrical-type strain gauges are used, then measurement precision is maintained for small displacements, but the capability to measure high displacement is limited
Solution Approach 1:
The patent uses a fluidic (hydraulic) system where an incompressible fluid is contained within a flexible membrane structure. When displacement is applied, the fluid transmits the mechanical deformation through hydrostatic pressure, enabling the strain gauge to measure large displacements while maintaining measurement precision through the fluid's incompressibility and the membrane's elastic properties.
Solution Approach 2:
The patent changes the physical state and properties of the sensing element from solid electrical conductors to incompressible fluid within a flexible membrane. This parameter change allows the system to accommodate large displacements while maintaining linear strain sensitivity, as the fluid can be compressed elastically within the membrane without the limitations of solid wire geometry.
2Stability of the object's composition
If solid alloy materials are used for strain gauges, then structural stability is maintained, but flexibility for large deformation measurement is limited
Solution Approach 1:
The patent employs a composite structure combining a flexible polymer membrane with an incompressible fluid filling. The polymer membrane provides structural stability and flexibility, while the fluid provides incompressibility and linear elastic response. This composite approach allows the strain gauge to withstand large deformations while maintaining measurement stability.
Solution Approach 2:
The patent uses a flexible polymer membrane as the containing structure for the fluidic sensing element. This thin film structure allows large deformations and displacements while maintaining the integrity of the fluid containment, enabling the strain gauge to measure high displacements that would exceed the elastic limits of solid alloy materials.
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 fluidic strain gauge demonstrates linear strain sensitivity up to 30% displacement, providing accurate and sensitive measurements suitable for biomedical applications.
Implementation Method 1
Fluidic piezoresistive strain gauge
Data Source
AI summary
The present invention relates to a strain gauge having a conductive fluid made of a glycerin/aqueous salt mixture, and methods of making the strain gauge. The strain gauge is capable of measuring large displacement of around 30% true strain.