Design of a Capacitive MEMS Accelerometer with Softened Beams.

Area of Science:

• Microelectromechanical Systems (MEMS)
• Sensor Technology
• Materials Science

Background:

• Capacitive microelectromechanical systems (MEMS) sensors are crucial for various applications.
• Sensor performance, particularly sensitivity and noise, is often limited by device stiffness.
• Lowering stiffness in MEMS devices is a key area for performance enhancement.

Purpose of the Study:

• To investigate the effectiveness of softened beams in improving capacitive MEMS accelerometer performance.
• To reduce the stiffness of a capacitive MEMS accelerometer using an electrostatic assembly approach.
• To quantify the impact of stiffness reduction on accelerometer sensitivity, noise, and bias instability.

Main Methods:

• Fabrication of MEMS accelerometers with softened beams via electrostatic assembly.
• Experimental characterization of the stiffness, sensitivity, noise, and bias instability of the modified accelerometers.
• Comparison of performance metrics between softened-beam accelerometers and conventional designs.

Main Results:

• Stiffness of the accelerometer was reduced by 43% using softened beams.
• Sensor sensitivity increased by 72.6% due to the reduced stiffness.
• Noise levels decreased to 26.2 μg/√Hz (44.5% improvement).
• Bias instability was reduced to 5.05 μg (38.7% enhancement).

Conclusions:

• The electrostatic assembly-based stiffness softening technique is highly effective for MEMS devices.
• Softer beams significantly enhance the performance of capacitive MEMS accelerometers.
• This technique holds potential for improving a wide range of MEMS sensor applications.