MEMS Sensor Non-Parallel Electrode Geometry
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Solution Overview
Problem
Existing sensors using MEMS elements face challenges in improving their characteristics, particularly in detecting fluid flow rates with high sensitivity and low power consumption while maintaining a simple configuration.
Innovation Solution
A sensor design featuring a first member with a fixed and movable electrode, where the movable electrode has non-parallel surfaces, allowing fluid to flow through a gap, causing a change in electrical capacitance, enabling sensitive flow rate detection with low power consumption, and potentially incorporating multiple layers of different materials for stress generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a MEMS element is used for sensor construction, then the sensor can be miniaturized and integrated, but the sensitivity and measurement precision deteriorate
Solution Approach 1:
The movable electrode is designed with a non-parallel surface configuration (inclined or curved) instead of a conventional parallel plate structure. This dimensional change in electrode geometry increases the effective detection area and enhances the capacitance change response to fluid flow, thereby improving sensitivity while maintaining the MEMS miniaturized form factor
Solution Approach 2:
The sensor employs an asymmetric electrode configuration where the movable electrode has a non-parallel surface relative to the fixed electrode. This asymmetry creates a more pronounced capacitance variation in response to fluid-induced displacement, enhancing measurement precision without increasing overall sensor volume
2Measurement precision
If the movable electrode surface is made non-parallel to improve sensitivity, then the flow rate detection precision improves, but the manufacturing complexity increases
Solution Approach 1:
The non-parallel surface configuration is achieved by controlling the deposition thickness or etching depth during manufacturing, transforming a geometric complexity into a controllable process parameter. This allows standard MEMS fabrication techniques to produce inclined or curved electrode surfaces with precise control, maintaining ease of manufacture while achieving improved sensitivity
3Measurement precision
If the gap between electrodes is reduced to increase capacitance sensitivity, then the measurement precision improves, but the device complexity increases due to tighter tolerances
Solution Approach 1:
By transitioning from a parallel plate geometry to a non-parallel surface geometry, the effective capacitance is enhanced through increased interaction area. This allows the use of larger physical gaps while maintaining high capacitance sensitivity, thereby reducing the stringency of gap tolerance requirements and simplifying device fabrication
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 sensor achieves high sensitivity in fluid flow rate detection with low power consumption and a simple configuration, capable of handling both gases and liquids, and can be adapted for various dynamic ranges.
Implementation Method 1
a change in electrical capacitance, enabling sensitive flow rate detection
Data Source
AI summary
According to one embodiment, a sensor includes a first member including a first member surface, and a first element part. The first element part includes a first fixed electrode fixed to the first member surface, and a first movable electrode facing the first fixed electrode. The first fixed electrode is along the first member surface. A gap is located between the first movable electrode and the first fixed electrode. The first movable electrode includes a first surface and a second surface. The first surface is between the first fixed electrode and the second surface. At least one of the first surface or the second surface is non-parallel to the first member surface.