Millimeter-Level MEMS Actuators Based on Multi-Folded Beams and Harmful Mode-Suppression Structures

Area of Science:

• Microelectromechanical Systems (MEMS)
• Optical Engineering
• Actuator Technology

Background:

• Module-level free-space optical interconnects necessitate actuators with both large stroke and high stability.
• Traditional folded-beam actuators face a trade-off between stroke and stability.
• Parasitic motion and crosstalk are critical challenges in actuator design for optical systems.

Purpose of the Study:

• To develop a millimeter-scale MEMS electromagnetic actuator that overcomes the stroke-stability trade-off.
• To integrate a Differential Motion Rejection (DMR) unit with a rigid frame for enhanced actuator performance.
• To systematically evaluate the actuator's performance through modeling, simulation, and experimental validation.

Main Methods:

• Magnetic-structural coupling modeling to understand electromagnetic-mechanical interactions.
• Finite element simulation to predict mechanical behavior and optimize design.
• Experimental characterization of stroke, resonant frequency, out-of-plane displacement, stiffness, and crosstalk.
• Optical testing to assess stable deflection angles for practical application.

Main Results:

• Achieved millimeter-scale stroke under sinusoidal drive with a primary resonant frequency of approximately 31 Hz.
• Reduced out-of-plane displacement at resonance by approximately 97% using the DMR and frame.
• Increased static Z-direction stiffness by over 50 times and decreased displacement crosstalk to 0.265%.
• Demonstrated a stable deflection angle of approximately ±21° through optical testing.

Conclusions:

• The developed MEMS electromagnetic actuator successfully combines large stroke with high stability.
• The integration of the DMR unit and rigid frame effectively suppresses parasitic motion and crosstalk.
• This actuator design is well-suited for module-level optical interconnect systems with demanding space and stability requirements.