This month’s edition of Nano Letters includes a paper from our Sheffield soft nanotechnology group (Jon Howse did most of the work, assisted by chemists Colin Crook and Paul Topham and beam line scientists Anthony Gleeson and Wim Bras, with me and Tony Ryan providing inspiration and/or interference) demonstrating the direct conversion of chemical energy to mechanical energy at the single molecule level. This is a development of the line of work I described here. Our idea is to combine a macromolecule which changes size in response to a change in the acidity of its surroundings with a chemical reaction which spontaneously leads to an oscillation in the acidity, to get a cyclic change in size of the polymer molecule. The work is summarised in a piece on nanotechweb.org.