Organic Piezoelectric Vibration Sensor With Low Frequency Dependence
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Solution Overview
Problem
Vibration sensors using piezoelectric materials face challenges in accurately evaluating objects due to significant frequency dependence in their output, leading to variations in electrical signal changes when the frequency of vibrations changes, even if the acceleration remains constant.
Innovation Solution
The use of an organic piezoelectric material, specifically a copolymer of vinylidene fluoride and one or more monomers copolymerizable with vinylidene fluoride, such as a vinylidene fluoride/tetrafluoroethylene-based copolymer, is employed in the vibration sensor to minimize frequency dependence in the output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional piezoelectric material is used in the vibration sensor, then the sensor can detect vibrations, but the output exhibits significant frequency dependence, leading to inaccurate evaluation when frequency changes
Solution Approach 1:
The patent changes the material parameter by using a copolymer composition with specific ratios of vinylidene fluoride (30-95 mol%) and tetrafluoroethylene (5-70 mol%). This compositional parameter change optimizes the piezoelectric properties to reduce frequency dependence while maintaining detection capability across a broad frequency range from 1 Hz to 1 MHz
Solution Approach 2:
The patent employs a composite piezoelectric material system consisting of vinylidene fluoride and tetrafluoroethylene copolymer. This composite approach combines the advantages of both monomers to achieve reduced frequency dependence and improved output linearity compared to conventional single-material piezoelectric sensors
2Measurement precision
If the piezoelectric material composition is optimized for specific frequency ranges, then output linearity improves, but the measurement range may be limited
Solution Approach 1:
The patent achieves multi-functionality by designing a copolymer material that simultaneously provides good output linearity and broad frequency response (1 Hz to 1 MHz). The specific compositional range of vinylidene fluoride (30-95 mol%) and tetrafluoroethylene (5-70 mol%) enables the material to function effectively across multiple frequency applications, from low-frequency (10 Hz to 2 kHz) to high-frequency measurements
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
This approach results in a vibration sensor with reduced frequency dependence, allowing for accurate evaluation of objects across a range of frequencies, particularly from 10 Hz to 2 kHz, with improved output linearity and stability.
Implementation Method 1
a vibration sensor using a piezoelectric material... can detect vibrations based on electrical signals generated by deformation of the piezoelectric material
Data Source
AI summary
An object of the present invention is to provide a vibration sensor in which the frequency dependence of the output is small. The present invention provides a vibration sensor 1 comprising: a support 2; an organic piezoelectric material 3 deformably disposed in or on the support 2; and an electrode 4 for extracting an electrical signal generated by deformation of the organic piezoelectric material 3, the electrode 4 being formed on the organic piezoelectric material 3, the organic piezoelectric material 3 comprising a copolymer of vinylidene fluoride and one or more monomers copolymerizable with vinylidene fluoride.