Study on the Dynamic Characteristics of a SiC-Based Capacitive Micro-Accelerometer in Rarefied Air

Area of Science:

• MEMS/NEMS
• Sensor Technology
• Fluid Dynamics

Background:

• Capacitive micro-accelerometers are sensitive to environmental conditions.
• Rarefied air significantly alters damping characteristics in micro-devices.
• Understanding these effects is crucial for reliable sensor operation.

Purpose of the Study:

• To investigate the impact of rarefied air on SiC-based capacitive micro-accelerometer performance.
• To derive an expression for effective air viscosity and analyze its effect on squeeze-film damping.
• To determine how changes in air pressure affect the accelerometer's dynamic characteristics.

Main Methods:

• Theoretical derivation of the effective viscosity coefficient in rarefied air.
• Analysis of squeeze-film air damping forces (viscous and elastic).
• Calculation and simulation of damping coefficient and relative damping ratio.

Main Results:

• Air viscosity and squeeze-film damping decrease with reduced air pressure.
• Damping coefficient and relative damping ratio are reduced in rarefied air.
• Micro-accelerometer operates in an underdamping state at low pressures, with reduced bandwidth and potential resonance, but unaffected response time.

Conclusions:

• Reduced air pressure significantly alters the dynamic performance of SiC-based capacitive micro-accelerometers.
• The study provides a theoretical framework for predicting accelerometer behavior in rarefied atmospheric conditions.
• This research is essential for optimizing micro-accelerometer design and application in low-pressure environments.