Piezoelectric Sensor Thermal Noise Cancellation via Segmented Layers
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Solution Overview
Problem
Piezoelectric sensors face challenges in detecting deflection of objects while canceling thermal gradient-induced noise, as existing designs either fail to detect deflection effectively or introduce noise when prioritizing thermal gradient cancellation.
Innovation Solution
A piezoelectric element with a laminate structure comprising a first and second piezoelectric layer, each with specific polarization directions, and an elastic layer between them, along with detection electrodes connected to terminal electrodes, allows for sensitive deflection detection while canceling thermal gradient-induced charges by exploiting the difference in expansion between the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the piezoelectric sensor uses a bimorph structure with upper and lower piezoelectric thin films to cancel thermal gradient-induced charges, then thermal noise is reduced, but the sensor cannot effectively detect deflection when both films are pulled by the target object
Solution Approach 1:
The piezoelectric sensor is divided into three distinct piezoelectric layers (first, second, and third layers) with different polarization directions. This segmentation allows each layer to contribute differently to charge generation, enabling simultaneous thermal noise cancellation and deflection detection. The first and third layers have opposite polarization directions to cancel thermal charges, while the second layer detects deflection charges.
Solution Approach 2:
Different regions of the piezoelectric sensor have different functional qualities. The first and third piezoelectric layers are configured with opposite polarization directions specifically for thermal noise cancellation, while the second piezoelectric layer is positioned and polarized to optimize deflection detection. This local differentiation of function resolves the contradiction between noise reduction and signal detection.
2Measurement precision
If the piezoelectric sensor is designed to prioritize deflection detection without canceling thermal charges, then deflection sensitivity is improved, but thermal gradient-induced noise is generated
Solution Approach 1:
The sensor structure segments the charge generation function across three layers with different polarization orientations. The first and third layers handle thermal compensation while the second layer handles deflection detection, allowing both functions to operate simultaneously without compromising either sensitivity or noise rejection.
Solution Approach 2:
The piezoelectric sensor achieves multi-functionality by making the three-layer structure capable of both thermal noise cancellation and deflection detection simultaneously. The first and third layers provide thermal compensation function while the second layer provides deflection detection function, making the single sensor structure universally capable of both tasks.
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
Enables high-sensitivity detection of deflection while effectively canceling thermal gradient-induced noise, improving the accuracy of deformation detection in piezoelectric sensors.
Implementation Method 1
piezoelectric substances deform, an electric charge generated by the deformation is detected as a bending
Implementation Method 2
a piezoelectric substance has pyroelectricity in which an electric charge is generated in accordance with a change in temperature
Data Source
AI summary
A piezoelectric element includes a laminate including first and second piezoelectric layers with respective polarization directions in a thickness direction and an elastic layer provided between the first piezoelectric layer and the second piezoelectric layer, first and second terminal electrodes that are provided on an external surface of the laminate, a first detection electrode provided on a positive polar surface of the first piezoelectric layer, a second detection electrode provided on a negative polar surface of the first piezoelectric layer, a third detection electrode provided on a positive polar surface of the second piezoelectric layer, and a fourth detection electrode provided on a negative polar surface of the second piezoelectric layer. The first detection electrode and the fourth detection electrode are connected to the first terminal electrode. The second detection electrode and the third detection electrode are connected to the second terminal electrode.