Ultrahigh-Speed Rotating Nanoelectromechanical System (NEMS) Devices   Assembled from Nanoscale Building Blocks
  The development of rotary nanomotors is crucial for further advancing NEMS technology. In this work, we report innovative design, assembly, and rotation of ordered arrays of nanomotors. The nanomotors were bottom-up assembled from nanoscale building blocks with nanowires as rotors, patterned nanomagnets as bearings, and quadrupole microelectrodes as stators. Arrays of nanomotors can be synchronously rotated with controlled angle, speed (to at least 18,000 rpm), and chirality by electric fields. Using analytical modeling, we revealed the fundamental nanoscale electrical, mechanical, and magnetic interactions in the nanomotor system, which excellently agrees with experimental results and provides critical understanding for designing future metallic NEMS devices. The nanowire motors were applied for controlled biomolecule release, and for the first time demonstrated releasing rate of biochemicals on nanoparticles can be tuned by mechanical rotation. The innovations reported in this research, from concept, design, actuation, to application are relevant to NEMS, nanomedicine, microfluidics, and lab-on-chip architectures. 
Kwanoh Kim, Xiaobin Xu and D. L. Fan
cond-mat.mes-hall