Piezoelectric Sensor Asymmetric Adhesive Layers
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Solution Overview
Problem
Conventional piezoelectric sensors face challenges in precisely detecting presses due to plate electrodes hindering deformation of the piezoelectric film, leading to insufficient voltage production and temperature-related fluctuations in sensor output.
Innovation Solution
A piezoelectric sensor design featuring a piezoelectric film with first and second plate electrodes and adhesive layers, where the first adhesive layer is thicker than the second, allowing strain from a plate member to be effectively transmitted to the film, and using a chiral polymer like poly-L-lactic acid to enhance piezoelectricity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the first adhesive layer is made thin to reduce distance between electrode and piezoelectric film, then charge extraction is improved, but the first plate electrode hinders deformation of the piezoelectric film more, reducing voltage production
Solution Approach 1:
The patent applies different thicknesses to the first and second adhesive layers attached to opposite surfaces of the piezoelectric film. The first adhesive layer (between the first electrode and film) is made thinner than the second adhesive layer (between the second electrode and film). This local differentiation allows the thinner first adhesive layer to minimize electrode hindrance to film deformation, thereby improving voltage production, while the thicker second adhesive layer compensates for strain alleviation. This resolves the contradiction between charge extraction efficiency and voltage production by creating asymmetric adhesive layer thicknesses tailored to each electrode's functional requirements.
2Force
If the second adhesive layer is made thick to alleviate strain of the plate member, then strain transmission is improved, but the first plate electrode hinders deformation of the piezoelectric film, reducing voltage production
Solution Approach 1:
The patent implements asymmetric adhesive layer thicknesses where the first adhesive layer is thinner and the second adhesive layer is thicker. The thicker second adhesive layer effectively transmits strain from the plate member to the piezoelectric film, while the thinner first adhesive layer minimizes the hindrance effect of the first electrode on film deformation. This local quality differentiation resolves the contradiction between strain transmission efficiency and voltage production by optimizing each adhesive layer's thickness for its specific functional role.
3Force
If adhesive layers are made thick to improve strain transmission, then deformation is improved, but temperature fluctuations cause softening that decreases sensor output
Solution Approach 1:
The patent employs asymmetric adhesive layer thicknesses with the first adhesive layer being thinner than the second adhesive layer. This asymmetry creates a balanced system where the combined effect of the two adhesive layers compensates for temperature-induced softening. The differential thickness configuration ensures that thermal expansion and softening effects are distributed unevenly, which counteracts the overall softening and maintains stable sensor output across temperature variations, thereby improving reliability while preserving strain transmission capability.
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 configuration enables precise detection of presses and improves temperature characteristics by canceling out fluctuations in sensor output caused by temperature changes, maintaining high sensitivity and reliability.
Implementation Method 1
When this transparent piezoelectric sheet is pressed, a voltage corresponding to the press is produced in the piezoelectric film
Implementation Method 2
By making the first adhesive layer thicker than the second adhesive layer, the strain of the plate member is readily transmitted to the piezoelectric film
Data Source
AI summary
A piezoelectric sensor that includes a piezoelectric film, first and second adhesive layers, first and second plate electrodes and a glass plate. The piezoelectric film includes first and second principal surfaces. The first adhesive layer attaches the first plate electrode to the first principal surface. The second adhesive layer attaches the second plate electrode to the second principal surface. The second plate electrode is attached to the glass plate such that the second adhesive layer and the second plate electrode are interposed between the piezoelectric film and the glass plate. The glass plate is distorted by being pushed. The second adhesive layer is thicker than the first adhesive layer.