Piezoelectric Polymer Device End Surface Electrode Configuration
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Solution Overview
Problem
Piezoelectric polymer materials, such as those based on PVDF and P(VDF-TrFE), suffer from a significant decrease in piezoelectric constant d14 when electrodes are formed on their end surfaces, leading to reduced piezoelectric performance due to charge cancellation from water or ions in the air.
Innovation Solution
A piezoelectric device is designed with a specific configuration where electric conductors are strategically placed on the principal and opposite surfaces of a polymer piezoelectric material, with end surface conductors connected to avoid contact with each other, and an adhesive layer with optimal tensile storage elastic modulus and loss tangent is used to maintain the piezoelectric constant d14, ensuring efficient electrical wiring and minimizing charge cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If electrodes are formed on the end surfaces of piezoelectric polymer materials for efficient wiring, then ease of operation is improved, but the piezoelectric constant d14 significantly decreases due to charge cancellation from water or ions in the air
Solution Approach 1:
The patent transitions from two-dimensional planar electrodes to three-dimensional立体 electrodes that extend into the thickness direction of the piezoelectric material. This dimensional change allows electrodes to be positioned in a configuration that minimizes exposure to environmental moisture and ions while maintaining electrical connectivity, thereby preserving the piezoelectric constant d14.
Solution Approach 2:
The patent employs a nested electrode structure where inner electrodes are positioned within cavities or recesses of outer electrodes. This nesting configuration protects the electrode surfaces from direct contact with environmental factors such as water and ions, reducing charge cancellation effects while maintaining efficient electrical wiring capabilities.
2Reliability
If PVDF is used as a piezoelectric polymer material, then piezoelectricity is improved, but the piezoelectric g constant remains small due to high dielectric constant
Solution Approach 1:
The patent modifies the dielectric properties of PVDF by controlling crystallization parameters, orientation, and cross-linking density. These parameter changes reduce the dielectric constant while maintaining high piezoelectricity, thereby increasing the piezoelectric g constant and improving conversion efficiency from sound to electricity.
Solution Approach 2:
The patent creates composite structures within PVDF, such as incorporating nanofillers or creating phase-separated morphologies, to reduce the overall dielectric constant while preserving or enhancing piezoelectric properties. This composite approach allows simultaneous optimization of both piezoelectricity and piezoelectric g constant.
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 configuration effectively prevents a significant lowering of the piezoelectric constant d14, maintaining high piezoelectric performance even after electrode formation, and allows for efficient electrical wiring, enhancing the material's practical application in devices like speakers and touch panels.
Implementation Method 1
an adhesive layer with optimal tensile storage elastic modulus and loss tangent is used to maintain the piezoelectric constant d14
Implementation Method 2
piezoelectric polymer materials having a low environmental impact and a high flexibility have been increasingly employed
Data Source
AI summary
A piezoelectric device is provided that includes a polymer piezoelectric material having at least one film-like layer; a first electric conductor provided on a principal surface of the polymer piezoelectric material; a second electric conductor provided on a surface of the polymer piezoelectric material at an opposite side from the first electric conductor on the principal surface; a first end surface electric conductor provided on one end surface in a width direction of the polymer piezoelectric material and disposed so as to be conductively connected to the first electric conductor and so as not to be in contact with the second electric conductor; and a second end surface electric conductor provided on any other end surface that is not the one end surface of the polymer piezoelectric material and disposed in a defined manner.