Researchers at San Diego University have demonstrated a way to 3D print tiny micro robots in shape of fish (like shark or manta ray) that can swim into a solution.
Each "fish" is just 120µm long and 30 µm thick (thinner than a human hair) and researchers have shown how they can be 3D printed inserting in the printing process specific materials, like platinum in the tail to make them react with hydrogen peroxide for propulsion or iron oxide in the head to be guided by a magnetic field plus drugs in the body to interact with toxins.
The micro-fish fabrication uses a technology called microscale continuous optical printing (µCOP) developed by Chen at UCSD. This allows the 3D printing of an array of hundreds of "fish" in a few seconds. µCOP is completely controlled by a computer so researchers can experiment with different shapes (mimicking different kinds of fish shape) and see which one works better.
The printing takes place through a chip made up of some 2 million mirrors individually controlled. UV light is directed by these mirrors to a photosensitive material that solidify. The 3D printing mechanisms lays one layer over the other deposing the required material at the required place with a µm precision.
According to the researchers the micro-fish could find different applications, from sensing the presence of a substance (like a toxin) in a fluid to delivering drugs (this is something that would require further work to find a way to release the drug when needed). They might also become useful as micro surgeons guided to the operating place by a magnetic field.
It looks to me that we have crossed the boundaries between science fiction and science....