Capacitive Accelerometer with Shared Mass for Compact Multi-Axis Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional three-axis capacitive accelerometers require increased volume to reduce mechanical noise, leading to oversizing and compromised sensitivity and linearity.
Innovation Solution
The design incorporates a substrate with a semiconductor layer featuring a mass, anchors, elastic members, and combo capacitor sets, where the elastic members bend perpendicular to the axes, allowing for efficient three-axis acceleration sensing while minimizing volume through optimized structural configurations and varying bending times and configurations of elastic members and capacitor fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three independent masses with related sensing electrode components are used to sense accelerations in X, Y, and Z axes independently, then the linearity and sensitivity of each sensing axis are protected from interference by other sensing axes, but the overall volume of the capacitive accelerometer increases, making it oversized
Solution Approach 1:
The patent combines three independent mass sensing systems into a single shared mass structure. The first, second, and third combo capacitor sets are all connected to the same first mass, allowing one mass to serve multiple sensing functions along different axes simultaneously, thereby reducing the need for three separate masses and their associated anchor and elastic member sets
Solution Approach 2:
The first mass performs multiple functions by being connected to different anchor and elastic member combinations that enable sensing along the first axis (via first combo capacitor set), second axis (via second combo capacitor set), and third axis (via third combo capacitor set). This multi-functional design allows a single mass to replace what would traditionally require three separate masses
Solution Approach 3:
The patent transitions from a conventional three-axis design to a four-axis sensing capability by adding the third axis (vertical direction) to the traditional two-plane (X-Y) sensing. This is achieved by orienting the third combo capacitor set vertically relative to the first and second combo capacitor sets, enabling detection of acceleration in the Z-direction in addition to the X and Y directions
2Object-affected harmful factors
If the overall volume of the capacitive accelerometer is increased to reduce mechanical noise, then mechanical noise received by the capacitive accelerometer is reduced, but the capacitive accelerometer becomes oversized and sensitivity and linearity are compromised
Solution Approach 1:
By merging the sensing functions for three axes into a single mass structure with shared anchor and elastic member components, the patent reduces the overall volume of the accelerometer while maintaining the ability to sense acceleration along multiple axes independently, thereby preserving sensitivity and linearity without requiring increased volume to suppress mechanical noise
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 enhances sensitivity and linearity while reducing the overall volume of the capacitive accelerometer, effectively addressing the challenge of mechanical noise and size constraints.
Implementation Method 1
The first elastic member is connected to the first mass and the first anchor in a manner of bending back and forth perpendicular to the first axis, for making the first mass move elastically along the first axis when a force is applied to the first mass in the first axis
Implementation Method 2
The second elastic member is connected to the first mass and the second anchor in a manner of bending back and forth perpendicular to the second axis, for making the first mass move elastically along the second axis when a force is applied to the first mass in the second axis
Implementation Method 3
Capacitive accelerometer
Data Source
AI summary
A capacitive accelerometer includes a substrate and a first semiconductor layer. The first semiconductor layer is disposed on the substrate and includes a first mass, first and second anchors, first and second elastic members, and first and second comb capacitor sets. The first and second anchors are disposed at positions corresponding to first and second axes respectively. The first elastic member is connected to the first mass and the first anchor in a manner of bending back and forth perpendicular to the first axis. The second elastic member is connected to the first mass and the second anchor in a manner of bending back and forth perpendicular to the second axis. The first and second comb capacitor sets are disposed at positions corresponding to the second and first axes respectively and connected to the first mass. The first axis is perpendicular to the second axis.