Elastomeric Composite Strain Gauge with Conductive Fillers
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Solution Overview
Problem
Existing strain gauges are limited in measuring strain magnitude, are expensive, difficult to calibrate, and suffer from drift, primarily measuring up to 2% strain, and are not suitable for field applications due to these limitations.
Innovation Solution
A uniform elastomeric composite material with conductive fillers and voids that exhibits piezoelectric and/or piezoresistive properties, capable of measuring strains up to 80% without permanent deformation, and does not require external power sources, allowing for integration into existing products for enhanced sensing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing strain gauges are used to measure strain, then measurement precision is maintained for small strains, but the measurement range is limited to 1-2% strain
Solution Approach 1:
The patent changes the material parameters by using an elastomeric polymer matrix with voids and conductive fillers instead of traditional metallic or semiconductor gauge materials. This allows the material to accommodate large deformations (up to 80% strain) while maintaining electrical conductivity through the conductive filler network, thus expanding the measurement range without sacrificing precision
Solution Approach 2:
The invention employs a composite material system consisting of an elastomeric polymer matrix, voids, and conductive fillers. This composite structure combines the high elasticity and large strain capability of elastomers with the electrical conductivity of filler materials, enabling both wide strain measurement range and acceptable measurement precision that neither material could achieve alone
2Measurement precision
If traditional strain gauges are deployed in field applications, then laboratory-grade measurement accuracy is achieved, but device complexity and calibration difficulty increase
Solution Approach 1:
The composite strain gauge material is designed to be self-calibrating through its inherent piezoresistive properties. The conductive filler network within the elastomeric matrix provides a straightforward electrical resistance-strain relationship that requires minimal external calibration equipment or procedures, making the device suitable for field applications while maintaining measurement accuracy
3Use of energy by moving object
If piezoelectric strain gauges are used to generate voltage under strain, then external power sources are eliminated, but drift phenomenon occurs over time
Solution Approach 1:
The patent replaces the piezoelectric effect with a piezoresistive effect-based measurement system. Instead of generating voltage through mechanical stress on piezoelectric crystals, the system uses changes in electrical resistance of the conductive filler network within the elastomeric matrix. This substitution eliminates the drift phenomenon associated with piezoelectric materials while still maintaining the benefit of not requiring external power sources, as the resistance change can be measured with simple voltage dividers
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 composite material provides a predictable and repeatable electromechanical response, reduces electrical resistance with increased strain, and eliminates drift, enabling accurate strain measurement across a broader range without the need for external power, making it suitable for various mechanical and biological applications.
Implementation Method 1
The composite material provides unexpected phenomena, piezoelectric response to deformation
Implementation Method 2
Both of these properties are valuable in sensing applications. A primary differentiator of the present material is that it exhibits a predictable and repeatable electromechanical response (piezoelectric and/or piezoresistive) at mechanical strains of up to 80% or more
Data Source
AI summary
In one general aspect, an apparatus comprises a material including a non-layered mixture of an polymeric foam with a plurality of voids; and a plurality of conductive fillers disposed in the polymeric foam. The apparatus may produce an electrical response to deformation and, thus, function as a strain gauge. The electrical response may be a decrease in electrical resistance. The electrical response may be an electric potential generated. The conductive fillers may include conductive nanoparticles and/or conductive stabilizers. In another general aspect, a method of measuring compression strain includes detecting, along a first axis, an electrical response generated in response to an impact to a uniform composite material that includes conductive fillers and voids disposed throughout an elastomeric polymer, and determining a deformation of the impact based on the electrical response. The impact may be along a second axis different from the first axis.