Nature Communications 6, Article number: 7429 (2015); Published: 11 June 2015; Updated: 9 July 2015

There were errors associated with the Supplementary Movie legends in the version of this Article originally published, which were introduced while the HTML was being prepared. The legends of Supplementary Movies 2, 3, 4, 8, 9 and 10 were incorrectly assigned to Supplementary Movies 10, 2, 3, 4, 8 and 9, respectively. There was also a typographical error in the legend of Supplementary Movie 10, which should read ‘UV light does not affect motion of a film of pure agarose over moist paper. (2) Heat does not affect motion of a film of pure agarose over moist paper. (3) Heat does not affect motion of a film of PCAD@AG over a moist paper. (4) The motion of PCAD@AG over a moist paper can be controlled by UV light.’ These errors have now been corrected in the HTML version of the Article; the PDF was correct from the time of publication.