Nested MEMS Capacitive Bridge for Multi-Axis Sensing
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Solution Overview
Problem
Current MEMS sensors require multiple discrete components to measure various characteristics, leading to increased size and complexity, especially as devices miniaturize, and struggle to efficiently determine location and orientation in multi-axis environments.
Innovation Solution
A fully differential capacitive bridge MEMS sensor with a proof mass and comb structure that senses acceleration and magnetic fields in multiple axes using a single chip, integrating capacitive elements and signal processing to determine displacement, orientation, and location by leveraging capacitive changes and electromagnetic forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple discrete sensor components are used to measure different characteristics, then measurement precision and versatility are improved, but device size and structural complexity increase
Solution Approach 1:
The patent combines multiple sensing functions (acceleration sensing along x, y, z axes and magnetic field sensing) into a single integrated MEMS device. The proof mass structure incorporates capacitive sensing elements for acceleration and magnetic field sensing capabilities within the same device footprint, eliminating the need for multiple separate sensor components and reducing overall system complexity while maintaining multi-axis measurement versatility
Solution Approach 2:
The MEMS sensor device performs multiple functions simultaneously: it measures acceleration along three axes and detects magnetic field components. The single proof mass structure serves as both the acceleration sensing element and the magnetic field interaction element, making the device universal for both inertial measurement and magnetic field detection applications
2Measurement precision
If multiple discrete sensor components are integrated into a device, then multi-axis measurement capability is improved, but the overall device size increases
Solution Approach 1:
The patent implements a nested proof mass configuration where an inner proof mass is positioned within or alongside an outer proof mass structure. This nested arrangement allows multiple sensing functions to be packed into a compact volume, enabling three-axis acceleration and magnetic field sensing without proportionally increasing the device size, as the sensing elements share the same spatial envelope
3Ease of manufacture
If discrete sensor components are used for each measurement characteristic, then ease of manufacture is improved, but device complexity and size increase
Solution Approach 1:
The patent merges multiple sensing functions into a single monolithic MEMS structure that can be fabricated using standard MEMS processing techniques. The capacitive elements, proof mass, and magnetic field sensing structures are all created in the same device through integrated fabrication processes, eliminating the need to assemble multiple discrete components and simplifying manufacturing while maintaining measurement capabilities
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
Enables compact, multi-axis sensing capabilities, reducing device size while accurately determining location and orientation by integrating capacitive and magnetic field sensing on a single chip, enhancing the precision and efficiency of MEMS technology.
Implementation Method 1
A first capacitive element and a second capacitive element are positioned on opposite sides of the proof mass such that the first capacitive element and the second capacitive element form a capacitive bridge
Implementation Method 2
senses acceleration and magnetic fields in multiple axes using a single chip, integrating capacitive elements and signal processing to determine displacement, orientation, and location by leveraging capacitive changes and electromagnetic forces
Data Source
AI summary
Apparatus, methods, and systems for sensing acceleration and magnetic fields in all three axes from a first capacitive bridge sensor having a first proof mass; and a second capacitive bridge sensor having a second proof mass located within the first proof mass. The second proof mass is coupled to the first proof mass by springs that permit movement in the second axis. Sensing of the remaining axis of interest may be done by a third and fourth capacitive bridge configured similar to that of the first and second capacitive bridge sensors. The third and fourth capacitive bridge sensors may be oriented 90 degrees off of the first and second capacitive bridge. An alternative is to locate a third capacitive bridge within the second proof mass.