  Slithering, crawling, slipping, gliding are various modes of limbless
locomotion that have been mimicked for micro-manipulation of soft, slender and
sessile objects. A lesser known mode is rolling which involves periodic,
asymmetric and lateral muscular deformations. Here we enable an elastomeric
cylinder of poly(dimethylsiloxane) to roll on a substrate by releasing small
quantity of a solvent like chloroform, toluene, hexane, heptane and so on,
which swells differentially a portion of the cylinder, but evaporates from
portion of it which remains exposed to the atmosphere. In a dynamic situation,
this asymmetric swelling-shrinking cycle generates a torque which drives the
cylinder to roll. The driving torque is strong enough that the cylinder can
roll up an inclined plane, within a range of inclination, its velocity even
increases. The cylinder can even drag a dead weight significantly larger, ~8-10
times its own weight. A scaling law is derived for optimizing the rolling
velocity.
