A millimetre-scale, magnetically controlled soft robot with multiple locomotion styles is reported online in Nature this week. This rectangular device - which can switch between crawling, walking and swimming while carrying cargo - may enable applications in microengineering and healthcare, like targeted drug delivery or minimally invasive surgery.

Existing small-scale robots designed to travel to locations that are inaccessible for humans tend to struggle to negotiate complex surfaces or terrains; but soft-bodied robots have greater mobility than their rigid counterparts. Metin Sitti and colleagues have developed a magnetically controlled silicone device that can switch between several locomotive styles, including rolling and jumping, depending on terrain. The device can transition from swimming through liquids to moving on solid unstructured surfaces without physical intervention and can pick up cargo, transport it and deposit it elsewhere.