PEDOT:PSS/WPU Strain Gauge With Staggered Cells for Large Strain Sensing
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Solution Overview
Problem
Existing strain gauges, particularly those made of metals and PEDOT:PSS, face issues such as high cost, complex manufacturing, brittleness, limited strain measurement capability, and unsuitability for human body applications due to stiffness and humidity dependence, which hinder their effectiveness in biomedical and large strain measurements.
Innovation Solution
A conductive polymer composite comprising PEDOT:PSS and waterborne polyurethane (WPU) is developed, with a staggered cellular structure that enhances mechanical strength, processability, and strain sensitivity, allowing for large strain measurements up to 400%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metal or semiconductor strain gauge is used, then measurement precision is improved, but device complexity and cost increase, and applicability to human body decreases due to stiffness
Solution Approach 1:
The patent employs a composite material system consisting of conductive polymer (PEDOT:PSS) embedded within an elastomeric matrix. This composite structure combines the electrical conductivity needed for strain measurement with the flexibility and softness required for human body applicability, resolving the contradiction between measurement precision and device complexity/applicability
Solution Approach 2:
The patent modifies the material parameters by using conductive polymers with tunable electrical properties and elastomeric matrices with adjustable mechanical properties. By changing the composition ratios and material parameters, the strain gauge achieves both adequate measurement precision and softness for human body contact without complex manufacturing
2Ease of manufacture
If PEDOT:PSS strain gauge is used, then processability is improved through inkjet printing or molding, but reliability deteriorates in large strain measurement due to brittleness and low strain limit
Solution Approach 1:
The patent embeds the brittle PEDOT:PSS conductive polymer within a flexible elastomeric matrix, creating a composite structure where the elastomeric shell protects the conductive polymer from mechanical failure during large strain measurements while maintaining the ease of manufacture through inkjet printing or molding processes
Solution Approach 2:
By creating a composite of PEDOT:PSS and elastomeric material, the patent combines the processability benefits of PEDOT:PSS with the mechanical reliability of elastomers, enabling both easy manufacturing and reliable large strain measurement capability
3Loss of time
If PEDOT:PSS material is used, then processing time is reduced through direct printing, but measurement precision deteriorates due to humidity dependence and low Young's modulus
Solution Approach 1:
The elastomeric matrix in the composite structure provides mechanical stability and reduces humidity dependence of the PEDOT:PSS conductive polymer, improving measurement precision while maintaining the rapid fabrication process through direct printing methods
Solution Approach 2:
By changing the composite material parameters and embedding PEDOT:PSS within the elastomeric matrix, the patent reduces the humidity sensitivity and stabilizes the Young's modulus, thereby improving measurement precision without increasing fabrication time
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 strain gauge exhibits improved mechanical properties, reduced hysteresis, and enhanced strain measurement capabilities, making it suitable for biomedical devices like smart bandages and ECG pads, as well as electronic devices like humidity sensors and touch screens.
Implementation Method 1
a conductive polymer composite includes poly(3,4-ethylenedioxythiophene) and waterborne polyurethane
Implementation Method 2
the strain sensitive layer has at least four separations arranged in a staggered way and forms bow-like structures, which makes the strain sensitive layer deform more in a first direction than a second direction perpendicular to the first direction
Data Source
AI summary
According to the present disclosure, a conductive polymer composite and a strain gauge are provided. The conductive polymer composite includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and waterborne polyurethane, and the conductive polymer composite is homogeneous. The strain gauge includes a substrate and a strain sensitive layer. The substrate has a surface, and the strain sensitive layer is connected to the surface of the substrate. The strain sensitive layer is made of the aforementioned conductive polymer composite, and the strain sensitive layer has at least four separations arranged in a staggered way and forms bow-like structures, which makes the strain sensitive layer deform more in a first direction than a second direction perpendicular to the first direction.