The mismatch between experimental and computational fluid dynamics analyses for magnetic surface microrollers

Area of Science:

• Biomedical Engineering
• Robotics
• Fluid Dynamics

Background:

• Magnetically actuated Janus surface microrollers show promise for biomedical applications.
• Existing locomotion models may not fully represent real-world microroller dynamics.

Purpose of the Study:

• To investigate the locomotion efficiency of surface microrollers across various sizes (5-50 µm).
• To evaluate the accuracy of computational fluid dynamics (CFD) simulations in predicting microroller locomotion.
• To identify discrepancies and propose explanations for observed locomotion behaviors.

Main Methods:

• Fabrication and testing of microrollers with diameters of 5, 10, 25, and 50 µm.
• Utilizing computational fluid dynamics (CFD) simulations to model microroller movement.
• Comparing simulation predictions with experimental observations, focusing on forces and locomotion efficiency.

Main Results:

• CFD simulations showed significant mismatches in predicting locomotion characteristics for different microroller sizes.
• A notable discrepancy was observed between simulated lift forces and balancing forces, especially for smaller microrollers.
• Experimental data suggests an unmodeled lift force component in CFD simulations.

Conclusions:

• CFD simulations are insufficient for accurately capturing the locomotion of surface microrollers across all sizes.
• An unaccounted force, likely in the lift direction, influences microroller dynamics.
• Findings enhance understanding of microrobotic physical mechanisms for improved biomedical engineering applications.