Swimming micro-machine driven by magnetic torque

Magnetic micro-machines capable of swimming through liquid or gel were fabr icated. The micro-machines were driven by an external rotating magnetic fie ld and featured a screw-shaped structure and permanent magnet. The machines could swim under condition of a Reynolds number (Re) of 10(-7) and were ab le to run through agar or a bovine tissue sample using the same principle. Their running behavior was dependent on the frequency and strength of the e xternal field, and on the surrounding media. These machines have great pote ntial for medical applications in the human body. (C) 2001 Elsevier Science B.V. All rights reserved.