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2005 Nuggets

Nano- and Microscale Motors Powered by Catalytic Reactions
W. E. Paxton, T. R. Kline, P. Lammert, S. Subramanian, V. H. Crespi, J. Catchmark, A. Sen, and T. E. Mallouk, IRG2

We are investigating micro/nanoscale motors driven by interfacial tension gradients generated in catalytic reactions. While catalytically driven motion on the nanoscale is ubiquitous in biology, it was previously unknown in artificial systems. Our first achievement was to make segmented nanorods with catalysts at one end. In aqueous hydrogen peroxide we observed linear and rotational autonomous movement at speeds up to 9 µm/sec. The speed of this movement is comparable to that of multi-flagellar bacteria, such as bacillus cereus). By adding magnetic Ni stripes for “steering,” we have made magnetotactic rods that are propelled parallel to an applied magnetic field. We have also demonstrated controlled rotational movement of a free gear measuring ~100 µm in diameter using interfacial tension gradients, and are developing microfluidic pumps based on catalytically driven movement of fluids over patterned surfaces.