Piezoelectric Sensor Cutout Corner Design
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Solution Overview
Problem
Conventional piezoelectric sensors face issues with cracks and electrode disconnection due to cutout portions in the piezoelectric film, which can lead to film breakage and operational failures.
Innovation Solution
The design includes a piezoelectric film with a cutout portion where the inner corner's normal direction does not align with the uniaxial stretching direction, and the inner corner has a radiused or polygonal shape to alleviate stress, using uniaxially stretched polylactic acid (PLLA) for enhanced sensitivity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a cutout portion is provided to the piezoelectric film to expose connection wires, then single-side contact connection is achieved, but cracks are produced from the inner corner of the rim near the cutout portion
Solution Approach 1:
The inner corner of the rim near the cutout portion is designed with a curved shape instead of a sharp corner. This curvature distributes stress more evenly around the cutout area, preventing stress concentration that would lead to crack initiation and propagation, thereby maintaining both connection accessibility and film integrity
Solution Approach 2:
The rim thickness is increased specifically at the inner corner region near the cutout portion, while other areas maintain their original thickness. This localized reinforcement provides additional structural support at the most vulnerable point without affecting the overall flexibility or electrical performance of the piezoelectric film
2Ease of manufacture
If the inner corner has a right-angle shape, then manufacturing is simplified, but stress concentration occurs leading to crack propagation
Solution Approach 1:
The inner corner is transformed from a right-angle shape to a curved shape with a specific radius. This geometric modification eliminates stress concentration points while maintaining manufacturability through standard curing processes, preventing crack initiation at the corner
3Measurement precision
If the piezoelectric film is uniaxially stretched to enhance piezoelectric effect, then sensitivity is improved, but the film becomes more prone to breaking in the stretching direction
Solution Approach 1:
The rim thickness is locally increased at critical regions near cutout portions and electrode edges, providing reinforced zones that compensate for the reduced overall strength caused by uniaxial stretching. This localized reinforcement prevents breakage in the stretching direction while preserving the enhanced piezoelectric sensitivity
Solution Approach 2:
Thicker rim structures are provided in advance at vulnerable locations before the piezoelectric film undergoes stretching or thermal stress. This preemptive reinforcement creates a buffer against stress concentration and potential failure, allowing the film to maintain high sensitivity after stretching
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 effectively prevents cracks in the piezoelectric film, ensuring reliable detection of signals with high sensitivity and improved durability against thermal stress.
Implementation Method 1
a piezoelectric sensor which detects a pressing operation, a bending operation, a twisting operation and the like
Implementation Method 2
The piezoelectric film is uniaxially stretched, and molecules are oriented in a uniaxial stretching direction
Data Source
AI summary
A capacitive sensor that includes a plurality of capacitance detection electrodes, an insulating substrate, a plurality of capacitance detection electrodes and an insulating substrate. A piezoelectric sensor includes a press detection electrode, a piezoelectric film, a plurality of press detection electrodes and an insulating substrate. The piezoelectric film includes a top surface on which the press detection electrode and wires are formed. The insulating substrate includes a top surface on which the plurality of press detection electrodes and wires are formed. The piezoelectric film includes a cutout portion through which part of the wires of the insulating substrate are exposed. A normal direction of an inner corner of the cutout portion of the piezoelectric film does not match with a uniaxial stretching direction of the piezoelectric film.