It's not quite as fantastic as shrinking people in a submarine into someone's bloodstream like in Fantastic Voyage, but it's very neat nonetheless.
Penn State University scientists have created self-propelling micromachines using spheres less than a micrometer wide:
Ayusman Sen of Pennsylvania State University in University Park and his colleagues have created the self-propelling microspiders using spheres less than a micrometre wide. Each sphere is made up of two halves – one hemisphere is gold, the other silica – and looks like a gold-and-silver Christmas bauble.
To turn the spheres into motors, the group attached a Grubbs catalyst – a molecule that builds long chains of smaller molecules – to the silica side. When Sen drops his spheres into a solvent containing the chemical norbornene, the catalyst spins a polymer from molecules of the chemical. Eventually there are far more unpolymerised single molecules of norbornene around the gold side of the sphere than the silica side , creating an osmotic gradient, as fluids will always move from a region with lots of particles to a region with fewer particles. The solvent rushes toward the gold side of the sphere, causing the whole sphere to move.
Sen's group were able to control the direction of the spheres' movement by placing lumps of gel soaked in norbornene at one corner of the tank of solvent. The thread-spinning spheres followed the trail of leached norbornene towards the gels.