A microscopic swimming robot unveiled by Chinese scientists could eventually be used for drug delivery or to clear arteries in humans, say researchers.
The 3 millimetre-long triangular machine was constructed by Tao Mei of the Chinese Academy of Sciences, Beijing, and colleagues from the University of Science and Technology of China.
The craft is propelled using an external magnetic field which controls its microscopic fins. The fins are made from an alloy that contracts in response to application of the field. Applying the field quickly makes the tiny submersible paddle forwards and gradually switching the field off slowly moves the fins back to their original position.
It is possible to control the speed of the craft by altering the resonant frequency of the magnetic field. The next stage is to build a robot with fins that respond to different magnetic field resonances. This would enable an operator to control the fin separately and steer the robot around.
Mei admits that the project is at an early stage but believes remote controlled swimming machines could be used to deliver drugs to a particular part of the human body, through the blood stream.
So far the Chinese scientists have tested a swimming device measuring 3mm x 2mm x 0.4mm but are working a new model just 1 mm long.
"We would like to make a 0.1mm one that could go inside the bloodstream," Mei told New Scientist. "Maybe we can make it even smaller using nanotechnology."
The team tested the device using magnetic fields of varying intensity, to rule out the possibility that it was simply being pulled by the field. They looked at the average speed and showed this could not be a result of magnetism on its own.
Kin Fong Lei, a robotics researcher from the Chinese University of Hong Kong, says this is the smallest swimming robot he has seen and believes it could have a number of applications. One previously reported swimming device, based on a cylindrical magnet, was 8mm long (New Scientist print edition, June 2001).
"With this type of swimming robot we could bring drugs to different parts of the human body more effectively," Lei says. "It could become very important for biological applications."
The swimming bot was revealed on Friday at the international conference on Intelligent Robots and Systems (IROS), in Sendai, Japan.
1 October 2004