  It has been recently shown that it is possible to design simple artificial
swimmers at low Reynoldsnumber that possess only one degree of freedom and,
nevertheless, can overcome Purcell's celebratedscallop theorem. One of the few
examples is given by Montino and DeSimone, Eur. Phys. J. E, vol.38, 2015, who
consider the three-sphere Swimmer of Najafi and Golestanian, replacing one
active armwith a passive elastic spring. We further generalize this idea by
increasing the number of springs andshow that it is possible to invert the
swimming direction using the frequency of the single actuatedarm.
