Ac/dc Magnetic Fields for Enhanced Translation of Colloidal Microwheels.

ABSTRACT: Microscale devices must overcome fluid reversibility to propel themselves in environments where viscous forces dominate. One approach, used by colloidal microwheels (μwheels) consisting of superparamagnetic particles assembled and powered by rotating ac magnetic fields, is to employ a nearby surface to provide friction. Here, we used total internal reflection microscopy to show that individual 8.3 μm particles roll inefficiently with significant slip because of a particle-surface fluid gap of 20-80 nm. We determined that both gap width and slip increase with the increasing particle rotation rate when the load force is provided by gravity alone, thus providing an upper bound on translational velocity. By imposing an additional load force with a dc magnetic field gradient superimposed on the

SUBMITTER: Disharoon D 

PROVIDER: S-EPMC6536127 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature