Micro-deformable Piezoresistive Material for Hysteresis-Free Pressure Sensing
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Solution Overview
Problem
Conventional piezoresistive materials exhibit hysteresis and inaccurate pressure measurement due to viscoelastic properties, leading to inconsistent resistance and conductivity readings when subjected to repeated pressure applications and releases.
Innovation Solution
A micro-deformable piezoresistive material with a hard plastic body and evenly dispersed conductive particles, featuring a micro-deformable rough texture surface, is used in pressure sensors, which minimizes thickness variation and eliminates hysteresis by maintaining a consistent contact area and gap between piezoresistive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional elastic piezoresistive material is used, then the material can recover to original state by viscoelasticity, but hysteresis and inaccurate pressure measurement occur after repeated operations
Solution Approach 1:
The patent changes the material parameters by transitioning from elastic material to rigid plastic material with specific yield strength properties. This parameter change eliminates viscoelastic hysteresis while maintaining measurement capability through controlled plastic deformation and crack formation mechanisms
Solution Approach 2:
The patent uses composite material structure combining rigid plastic matrix with conductive particles (carbon black, graphite, or metal particles). This composite structure provides both the rigidity needed to eliminate hysteresis and the electrical conductivity needed for pressure sensing
2Measurement precision
If piezoresistive material deforms under pressure, then resistance changes can be measured, but thickness variation causes inconsistent readings
Solution Approach 1:
The patent changes the deformation behavior from elastic thickness reduction to controlled plastic deformation with minimal thickness change. The rigid plastic material maintains relatively constant thickness while developing internal cracks that alter electrical resistance, providing consistent measurements
3Measurement precision
If piezoresistive layers contact each other under pressure, then resistance decreases, but contact area variation causes hysteresis
Solution Approach 1:
The patent changes the mechanism from contact-area-dependent resistance change to crack-density-dependent resistance change. The rigid plastic material prevents significant contact area variation while internal crack formation and conductive particle redistribution provide the resistance change signal
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 solution effectively eliminates hysteresis phenomena, ensuring accurate and reliable pressure sensing by maintaining identical pressure-resistance and conductivity curves during both pressure application and release, enhancing the sensor's accuracy and reliability.
Implementation Method 1
a piezoresistive material having a micro-deformable rough texture surface... Resistance of the piezoresistive material can be calculated by the equation R=ρ*L/A
Data Source
AI summary
A micro-deformable piezoresistive material is provided, including a hard plastic body, a micro-deformable rough texture surface, and a plurality of conductive particles. The micro-deformable rough texture surface is formed on a side of the hard plastic body, wherein the maximum deformation of the rough texture surface is far less than the thickness of the hard plastic body. Additionally, the conductive particles are evenly dispersed in the plastic body.