Particle-stabilized oscillating diver: a self-assembled responsive   capsule
  We report the experimental discovery of a self-assembled capsule, with density set by interfacial glass beads and an internal bubble, that automatically performs regular oscillations up and down a vial in response to a temperature gradient. Similar composites featuring interfacial particles and multiple internal compartments could be the solution to a variety of application challenges. 
Joe W. Tavacoli, Job H. J. Thijssen and Paul S. Clegg
cond-mat.soft