Piezoresistive_Composites_Flashcards
What is the key difference between piezoresistive and piezoelectric materials?
Piezoresistive materials require external voltage, while piezoelectric materials generate signals autonomously under mechanical stress.
What happens in piezoresistive materials under mechanical load?
Their resistance changes in response to mechanical load.
What happens in piezoelectric materials under mechanical load?
They generate an electric charge.
What are intrinsic conductive polymers?
Polymers that inherently possess a conjugated structure allowing for electrical conductivity.
What are extrinsic conductive polymers?
Polymers that gain conductivity by incorporating conductive fillers.
How can the piezoresistive properties of natural rubber be optimized?
By optimizing cross-linking and filler distribution.
What are common fillers used in piezoresistive composites?
Carbon black, carbon nanotubes (CNTs), and graphene.
What factors affect the choice of fillers in composites?
Cost, conductivity, dispersion challenges, and percolation thresholds.
What effect does low strain have on piezoresistive materials?
It induces tunneling effects.
What effect does high strain have on piezoresistive materials?
It disrupts conductive pathways.
What is a strain gauge sensor?
A passive resistive transducer that converts strain into changes in electrical resistance.
What materials are commonly used for strain gauges?
Metals like gold, silver, copper; semiconductors like silicon, germanium, and silicon carbide.
What is an advantage of metal strain gauges?
High-temperature endurance and durability.
What is an advantage of semiconductor strain gauges?
Higher sensitivity for measuring small strains.
What is a limitation of traditional strain gauges?
They are limited to a strain range of less than 10%.
What processing methods are used for elastomer-based composites?
Casting, molding, extrusion, and additive manufacturing.
How does increasing carbon content affect resistive composites?
It enhances conductivity but stiffens the material.
What challenges arise in integrating soft sensors into structures?
Homogeneous filler distribution, adhesion, and avoiding slippage under stress.
How does matrix stiffness affect sensor performance?
A stiffer matrix increases robustness but reduces sensitivity, while a softer matrix increases sensitivity but reduces durability.
What do gauge factors (GF) measure?
They measure the change in resistance relative to strain.
What challenges exist with composite models for gauge factors?
They are often specific to particular matrix and filler combinations.
What is direct writing (robocasting) used for?
Creating custom-designed sensors with high spatial resolution.
What is fused deposition modeling (FDM)?
A 3D printing method for creating elastomer-based composites.
What are some applications of piezoresistive composites in robotics?
Soft grippers, 3D-printed robotic fingers, and pneumatic bending actuators.
How are soft grippers used?
For material handling and pick-and-place tasks in robotics.
