Acoustic Sensor Sticking Prevention via Non-Uniform Electrode Thickness
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Solution Overview
Problem
Conventional acoustic sensors face challenges with sticking issues between the vibrating electrode plate and the counter electrode plate due to capillary forces, surface tension, and electrostatic forces, which hinder the detection of sound pressure, and existing solutions either compromise sensitivity or miniaturization.
Innovation Solution
The acoustic sensor design incorporates a substrate with a vibrating electrode plate and a counter electrode plate separated by an air gap, featuring projections on one of the plates with varying intervals to reduce sticking, allowing for effective vibration detection while maintaining sensitivity and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between the vibrating electrode plate and the counter electrode plate is reduced to enhance sensitivity, then measurement precision is improved, but the capillary force of invading water increases causing sticking
Solution Approach 1:
The invention applies local quality by making the vibrating electrode plate non-uniform in thickness. The plate has a thinner region (first thickness) and a thicker region (second thickness greater than the first). The thicker region provides structural support to resist capillary forces, while the thinner region maintains sensitivity for acoustic detection. This local variation in thickness allows the plate to function effectively despite the small gap between electrodes.
2Measurement precision
If the vibrating electrode plate is made thinner to enhance sensitivity, then measurement precision is improved, but the spring property is weakened making the plate more susceptible to sticking
Solution Approach 1:
The vibrating electrode plate is designed with non-uniform thickness where a first region has a first thickness and a second region has a second thickness greater than the first thickness. This local quality variation allows the thinner first region to maintain high sensitivity for acoustic detection while the thicker second region provides enhanced spring property and structural support to prevent sticking to the counter electrode plate.
3Reliability
If projections are provided on the electrode plate to reduce sticking, then reliability is improved, but device complexity increases
Solution Approach 1:
The invention changes the thickness parameter of the vibrating electrode plate by creating a non-uniform thickness distribution. Instead of adding complex projection structures, the patent varies the thickness parameter locally - with a first thickness in one region and a greater second thickness in another region. This parameter change effectively prevents sticking by providing structural support where needed while maintaining the simplicity of the overall device structure.
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 design effectively reduces sticking by optimizing the interval between projections, stabilizing the sensor's characteristics, and enhancing its frequency response, allowing for reliable operation across varying conditions.
Implementation Method 1
an acoustic sensor that detects a sound pressure propagating through gas or liquid, that is, acoustic vibration
Implementation Method 2
the counter electrode plate 13 attracts the vibrating electrode plate 12 by a capillary force P1 or a surface tension of the water 14
Implementation Method 3
after evaporation of the water 14 between the vibrating electrode plate 12 and the counter electrode plate 13
Implementation Method 4
acoustic vibration is detected by detecting a change in electrostatic capacitance between the vibrating electrode plate and the counter electrode plate
Data Source
AI summary
A vibrating electrode plate that senses a sound pressure faces a counter electrode plate to constitute a capacitance type acoustic sensor. In the counter electrode plate, acoustic perforations are opened in order to pass vibration, and plural projections are provided on a surface facing the vibrating electrode plate. An interval between the projections is decreased in a region where the vibrating electrode plate has high flexibility to easily generate local sticking with the counter electrode plate. The interval between the projections is increased in a region where the vibrating electrode plate has low flexibility to hardly generate local sticking with the counter electrode plate. The projections thus arranged prevent firm fixing of the vibrating electrode plate to the counter electrode plate and interruption of vibration of the vibrating electrode plate.