Design Study of a Diamagnetic Long-Range Movement Stage Actuated by Electrostatic Force
L.A.J. Wiedenhoff (TU Delft - Mechanical Engineering)
P.G. Steeneken – Mentor (TU Delft - Precision and Microsystems Engineering)
F. Alijani – Graduation committee member (TU Delft - Dynamics of Micro and Nano Systems)
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Abstract
Diamagnetic levitation provides a frictionless and entirely passive method of actuation, operating even in vacuum and at cryogenic temperatures. It has been explored in fields ranging from seismology to microfluidics handling, and its qualities make it attractive for MEMS devices by reducing production costs and improving robustness. This work develops a diamagnetic motion stage aimed at extending the achievable range of motion beyond prior nanometer-scale demonstrations. This objective is formulated as the following research question: What would be an optimal design for a long range actuator to create maximum move- ment range using diamagnetic levitation to eliminate contact friction and electrostatic force as propulsion method using only feedforward control, while keeping the cost low?. Magnet arrays were modeled, with a railroad configuration selected for its levitation properties. An electrostatic actua- tion model was derived, showing that force depends on both electrode area and its change as a result of movement, and that stable control requires balancing charged and grounded electrodes. Two systems were implemented: a low-voltage (0–200 V) setup with high control but low force, and a high-voltage (0–1200 V) setup with greater force but less control. Characterization revealed Duffing- type nonlinear dynamics. The low-voltage stage enabled three-phase frequency control, useful for resonance testing, while the high-voltage stage achieved up to 5.5 mm controlled travel and 23.47 mm one-way displacement, though with the end position being unrecoverable using electrostatics. The results show that longer travel requires repeating magnet arrays where all potential local minima support levitation. Another important finding was that electrostatic force has both x and z components, with their ratio depending on levitation height and stage surface area, highlighting the importance of thin electrodes. Scaling analysis suggests further potential for MEMS integration.