Capacitive Pressure Sensor Shield Electrode Power Reduction
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Solution Overview
Problem
Capacitance pressure sensors consume unnecessary electric power due to electrostatic capacitance between the shield electrode and the membrane, which reduces sensor sensitivity when attempts to reduce this capacitance also decrease the distance between the stationary electrode and the membrane, thereby decreasing sensitivity.
Innovation Solution
A pressure sensor design with a side-wall portion that includes a shield electrode and a second insulating layer, where the distance between the stationary electrode and the membrane is less than the distance between the shield electrode and the membrane, reducing power consumption without degrading sensitivity by maintaining or enhancing sensitivity through a multi-tier membrane structure and optimized electrode configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the insulating layer at the side-wall portion is thickened to reduce the electrostatic capacitance between the shield electrode and the membrane, then the electrostatic capacitance between the shield electrode and the membrane is reduced, but the distance between the stationary electrode and the membrane increases, which decreases the sensor sensitivity
Solution Approach 1:
The patent applies local quality by creating a multi-tier insulating layer structure where different regions have different thicknesses. Specifically, the first insulating layer has a first thickness in a first region and a second thickness in a second region, with the first thickness being greater than the second thickness. This allows the shield electrode to be positioned at different distances from the membrane in different regions, reducing the parasitic capacitance locally without affecting the overall sensor sensitivity.
Solution Approach 2:
The patent introduces a vertical dimensionality change by creating a multi-tier structure with insulating layers at different heights. The first insulating layer is positioned at a first height and the second insulating layer at a second height, forming a stepped configuration. This three-dimensional arrangement allows the shield electrode to be isolated from the membrane in certain areas while maintaining close proximity in other areas, thus reducing power consumption without sacrificing sensitivity.
2Use of energy by moving object
If the distance between the shield electrode and the membrane is increased to reduce power consumption, then the electrostatic capacitance between them is reduced, but this requires thickening the insulating layer which also increases the distance between the stationary electrode and the membrane
Solution Approach 1:
The patent implements local quality by varying the insulating layer thickness in different regions. The first insulating layer with greater thickness is provided in a first region to increase distance and reduce capacitance, while the second insulating layer with lesser thickness is provided in a second region to maintain shorter distance. This spatial variation allows selective control of electrode spacing to optimize both power consumption and sensitivity.
Solution Approach 2:
The patent segments the insulating layer structure into multiple distinct layers with different thicknesses and positions. The first insulating layer and second insulating layer are separated in both vertical and horizontal dimensions, creating distinct functional zones. This segmentation enables independent optimization of different regions - one for power reduction and another for sensitivity maintenance.
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
The design effectively reduces electric power consumption by the electrostatic capacitance between the shield electrode and the membrane while maintaining or improving sensor sensitivity by ensuring a larger electrostatic capacitance between the stationary and membrane electrodes, thus enhancing the overall performance of the pressure sensor.
Implementation Method 1
the side-wall portion includes a shield electrode provided at the insulating layer and an insulating layer provided toward the membrane at the shield electrode. This shield electrode reduces effects of the electrostatic capacitance (parasitic capacitance) of the side-wall portion
Implementation Method 2
The pressure on the membrane is detected (calculated) in accordance with the electrostatic capacitance between the membrane and the stationary electrode
Data Source
AI summary
A pressure sensor includes a base substrate, a first insulating layer at the base substrate, a stationary electrode at the first insulating layer, a side-wall portion around the stationary electrode at the first insulating layer, and a membrane having electrical conductivity, facing the stationary electrode across a space, and supported by the side-wall portion. The side-wall portion includes a shield electrode on the first insulating layer and a second insulating layer on the shield electrode. A distance between the stationary electrode and the membrane is less than a distance between the shield electrode and the membrane.