MEMS Sensor with Non-Parallel Movable Electrodes for Multi-Axis Acceleration
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Solution Overview
Problem
Existing MEMS sensors face challenges in accurately detecting acceleration in multiple directions while being miniaturized, as they struggle with sensitivity and precision due to limitations in capacitance detection methods.
Innovation Solution
The design incorporates a sensor structure with a substrate, non-parallel movable electrodes, and fixed electrodes, utilizing differential capacitance detection and a manufacturing method involving sacrificial films and SiGe layers to enhance sensitivity and miniaturization, allowing for accurate acceleration detection in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional capacitance detection methods are used in miniaturized MEMS sensors, then sensor size is reduced, but detection accuracy and sensitivity deteriorate
Solution Approach 1:
The patent divides the capacitance detection into multiple independent capacitor units arranged in series. Each capacitor unit consists of a movable electrode and fixed electrodes, allowing the total capacitance change to be distributed across multiple segments. This segmentation enables miniaturization while maintaining detection sensitivity through cumulative capacitance measurement.
Solution Approach 2:
The patent transitions from single-capacitor detection to multi-dimensional capacitance measurement by arranging multiple capacitor units in series along different spatial dimensions. The movable electrode can shift position to change capacitance in multiple directions simultaneously, enhancing detection accuracy while reducing individual component size.
2Device complexity
If single capacitor structure is used, then device complexity is low, but offset cancellation capability is insufficient
Solution Approach 1:
The patent introduces different types of fixed electrodes (first fixed electrode and second fixed electrode) with potentially different properties or positions relative to the movable electrode. Each fixed electrode creates a capacitor unit with specific local characteristics, enabling differential measurement and offset cancellation while maintaining overall structural simplicity.
Solution Approach 2:
The patent creates multiple capacitor units by replicating the basic capacitor structure (movable electrode with fixed electrodes) multiple times in series. This copying approach allows for offset cancellation through differential measurement while avoiding complex single-capacitor designs.
3Adaptability or versatility
If non-parallel movable electrodes are used, then multi-directional acceleration detection is enabled, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the movable electrode structure into multiple independent movable electrodes, each capable of responding to acceleration in different directions. Each segment can be manufactured and aligned independently, reducing the overall manufacturing precision requirement while enabling multi-directional detection capability.
Solution Approach 2:
The patent employs non-parallel arrangement of movable electrodes with different orientations relative to the fixed electrodes. This asymmetric configuration enables detection of acceleration in multiple directions while allowing each electrode to be manufactured with standard precision tolerances, as the directional sensitivity is achieved through geometric arrangement rather than requiring ultra-precise alignment.
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 approach improves detection accuracy by canceling offsets and enabling downsizing of MEMS sensors, allowing for precise measurement of acceleration in multiple axes while maintaining sensitivity.
Implementation Method 1
a first capacitance between the first fixed electrode and the movable electrode and a second capacitance between the movable electrode and the second fixed electrode
Implementation Method 2
Sensors in which micro-electromechanical systems (MEMS) technology is used to detect physical quantities such as acceleration or pressure are known
Data Source
AI summary
According to one embodiment, a sensor is disclosed. The sensor includes a substrate, a first fixed electrode arranged on the substrate, a movable electrode arranged above the first fixed electrode and being movable non-parallely, a second fixed electrode arranged above the movable electrode. The sensor further includes a detector to detect a difference between a first capacitance between the first fixed electrode and the movable electrode and a second capacitance between the movable electrode and the second fixed electrode.