Micromotors with built-in compassesThis article is part of the ChemComm 'Microfluidics' web themed issue.Electronic supplementary information (ESI) available: Experimental section. See DOI: 10.1039/c2cc35671f

We demonstrate here that iron containing rolled-up microtubular engines can be magnetized and act as compass needles - they sense the direction of an external magnetic field from afar and align the directionalities of their movements according to the external field, in a similar fashion to magnetotactic bacteria. Magnetized iron containing microjets can sense the direction of an external magnetic field and align the directionalities of their movements accordingly.