MEMS Rotor Segmentation for Electrical Isolation
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Solution Overview
Problem
Existing MEMS devices with moving rotors face challenges in measurement accuracy and reliability due to electrical disturbances caused by physical contact between stopper structures and stators, especially when the rotor and stator are at different potentials, and the need for separate stopper structures to prevent short-circuiting and charge accumulation.
Innovation Solution
The solution involves creating two or more electrically separated regions in the rotor, with a stopper structure where the electric potential of the rotor and stator are equal, using a silicon rotor with a rotor stopper region and a stator stopper region separated by a stopper gap, and an insulating material to connect these regions mechanically while isolating them electrically, allowing for improved measurement accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the entire rotor is set to a given electric potential to form capacitive transducers, then the electrical wiring complexity is reduced, but physical contact between stopper structures creates electrical disturbances in measurements
Solution Approach 1:
The rotor is segmented into two electrically isolated regions: a first region that forms capacitive transducers with the stator and a second region that forms stopper structures. This segmentation allows different electric potentials to be applied to different regions, preventing electrical disturbances during stopper contact while maintaining the simplified wiring benefit for the transducer region.
Solution Approach 2:
An insulating material layer is introduced between the first and second regions of the rotor to electrically isolate them. This intermediary layer prevents electrical charge transfer between regions, allowing the stopper region to contact the stator without creating electrical disturbances in the measurement transducers.
2Reliability
If stopper structures are implemented on the rotor, then mechanical protection is provided, but electrical contact between rotor and stator causes sudden electrical changes and measurement disturbances
Solution Approach 1:
The rotor is divided into functional regions: a first region for capacitive transducers and a second region for stopper structures. This segmentation isolates the stopper contact function from the measurement function, allowing mechanical protection without electrical interference in the measurement region.
Solution Approach 2:
The second region (stopper region) and the stator are maintained at the same electric potential, eliminating potential differences that would cause electrical disturbances during contact. This equipotential condition allows safe mechanical contact without electrical interference in measurements.
3Measurement precision
If the rotor is separated into two electrically separated regions, then electrical disturbances are reduced, but the device complexity increases
Solution Approach 1:
The rotor is segmented into two regions separated by an insulating layer, achieving electrical isolation to protect measurements. This segmentation is implemented through standard MEMS fabrication techniques, balancing structural complexity with measurement accuracy requirements.
Solution Approach 2:
A thin insulating material layer serves as the separator between the two rotor regions. This intermediary structure provides electrical isolation while occupying minimal space, reducing the impact on device complexity compared to more substantial separation methods.
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 enhances measurement accuracy and device reliability by preventing electrical disturbances and ensuring that the rotor and stator stopper regions can be set to the same potential, reducing the risk of short-circuiting and charge accumulation, thus maintaining precise capacitive transducer measurements.
Implementation Method 1
a first rotor isolation region made of an insulating material which connects the first rotor measurement region mechanically to the rotor stopper region and isolates the first rotor measurement region electrically from the rotor stopper region
Implementation Method 2
The motion of the rotor is typically measured (and in the case of gyroscopes, also actuated) with electrical transducers. These transducers may for example be capacitive transducers with two opposing electrode structures
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~2e
AI summary
This disclosure describes a microelectromechanical device comprising at least one mobile rotor. The rotor comprises a rotor measurement region and a rotor stopper region and a rotor isolation region which connects the rotor measurement region mechanically to the rotor stopper region and isolates the rotor measurement region electrically from the rotor stopper region.