In-Plane MEMS Accelerometer Flux Leakage Reduction
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Solution Overview
Problem
Accelerometers constructed on silicon-on-insulator wafers with electrical traces forming coils on one side of the proof mass face challenges in cost-effective construction and susceptibility to external magnetic fields, leading to performance issues and flux leakage.
Innovation Solution
An in-plane Micro Electro-Mechanical Systems (MEMS) accelerometer device is designed with a magnetic flux field perpendicular to its major plane, featuring conductive coil traces, spring elements, anchor pads, sense combs, and damping combs, along with isolation trenches and slots to enhance performance and reduce flux leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrical traces form a coil on one side of the proof mass, then the device can be constructed on a single SOI wafer, but flux leakage and susceptibility to external magnetic fields increase
Solution Approach 1:
A non-conductive layer is introduced between the coil traces and the proof mass, serving as an intermediary that blocks magnetic flux leakage while allowing the coil to remain functional. This mediator prevents direct magnetic coupling between the coil and proof mass, reducing unwanted flux leakage.
Solution Approach 2:
The coil traces are configured to extend beyond the proof mass boundaries in the planar dimension, allowing the coil to be positioned in a different spatial relationship to the proof mass. This dimensional arrangement reduces magnetic coupling and flux leakage while maintaining the single-wafer construction benefit.
2Ease of manufacture
If electrical traces form a coil on one side of the proof mass, then the device can be constructed on a single SOI wafer, but susceptibility to external magnetic fields increases
Solution Approach 1:
The non-conductive layer acts as a magnetic shield intermediary, reducing the coupling between external magnetic fields and the coil traces. This mediator layer helps isolate the coil from external magnetic interference while maintaining the single-wafer construction advantage.
Solution Approach 2:
By extending the coil traces beyond the proof mass boundaries in the planar dimension, the coil is positioned in a spatial configuration that reduces exposure to external magnetic fields affecting the proof mass, while maintaining manufacturability on a single SOI wafer.
3Ease of operation
If coil traces loop over the coil to exit the proof mass, then electrical connection is achieved, but performance issues arise
Solution Approach 1:
The coil traces are designed to exit the proof mass by extending in the planar dimension beyond the proof mass boundaries, rather than looping vertically over the coil. This dimensional change eliminates the looping structure that causes performance issues while maintaining electrical connectivity.
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 device achieves improved performance by minimizing flux leakage and external magnetic field susceptibility, allowing for effective servoing of the proof mass while maintaining cost-effectiveness.
Implementation Method 1
one or more components for generating a magnetic flux field. The magnetic flux field being perpendicular to a major plane of the device... a plurality of conductive coil traces located at a position on the proof mass proximate the magnetic flux field
Implementation Method 2
a spring element that flexibly connects the proof mass to the substrate for allowing motion of the proof mass in the major plane
Implementation Method 3
a plurality of conductive springs, each of the springs being electrically connected to a corresponding one of the conductive coil traces
Data Source
AI summary
An in-plane, closed-loop Micro Electro-Mechanical Systems (MEMS) accelerometer device with improved performance. An example MEMS device includes one or more components for generating a magnetic flux field perpendicular to a major plane of the device. The device includes substrates, a proof mass, spring elements that flexibly connect the proof mass to the substrate and constrain the proof mass to translate within the major plane of the device which corresponds to a major surface of the proof mass, a plurality of conductive traces located at a position on the proof mass proximate the magnetic flux field, a plurality of conductive springs, each of the springs are electrically connected to a corresponding one of the conductive traces, and a plurality of anchor pads connected to the substrate and one of the conductive springs.