Researchers have been able to fabricate microscopic fish slapped nanobots they call Microfish. These nanobots are able to move within liquid very precisely as researchers control their every movement. They do this by embedding the fish with both iron-oxide and Platinum. They propel the fish using hydrogen peroxide which mixes with the platinum to create a fuel. They then can magnetically steer the fish based on the iron-oxide they print within the head of each. The fish measure a staggeringly tiny 120 microns in length and can be printed in mere seconds. More details on this incredibly research can be found here: http://3dprint.com/77456/3d-printed-microfish/


Below is a diagram further explaining the process used here: