Researchers at Rensselaer Polytechnic Institute have developed liquid pistons, which can be used to precisely pump small volumes of liquid. Comprising the pistons are droplets of nanoparticle-infused ferrofluids, which can also function as liquid lenses that vibrate at high speeds and move in and out of focus as they change shape. Seen here is a video taken through a liquid lens driven by liquid pistons. As the droplet oscillates, the picture moves in and out of focus. These liquid pistons could enable a new generation of mobile phone cameras, medical imaging equipment, implantable drug delivery devices, and possibly even implantable eye lenses.