Mini-robot invented that swims along blood vessels
A robot mole that can swim along blood vessels and burrow into tissue to deliver drugs or lance tumours has been successfully tested.
The machine, slightly bigger than a grain of rice and shaped like a corkscrew, passed through a 2cm thick chunk of beef steak in 20 seconds.
Japanese scientists believe that, in future, the tiny spinning screws could transform treatment for infections and cancer. Patrolling the body, they could ferry drugs to sites of infection or, tipped with a hot probe, lance and kill tumours.
However some experts have warned of the danger of such devices blocking a vital blood vessel. Kazushi Ishiyama, of Tohoku University, who designed the robots, said the machines may become small enough to negotiate narrow blood vessels.
The swimming micro-machines are based on cylindrical magnets, New Scientist magazine has reported. Each robot is just eight millimetres long and less than a millimetre in diameter.
Two test prototypes have been developed. The first was designed to move in liquids and was successfully tested in a container of silicone oil fixed between two vertical coils of wire.
Passing alternating current through the coils generated a rotating magnetic field which caused the screw to spin and cut through the oil. As the magnetic field frequency was raised, its speed increased.
The second prototype, designed to swim and burrow into tissue, had a threaded brass tip at one end. This device was able to move at nearly 2cm per second in thick agar gel. It was also able to burrow easily through steak.
The latest version is even armed with a tiny metal spike that heats up when a second magnetic field is applied. The spike could be useful for destroying cancerous tissue, says Ishiyama.
In practice, the machines would be injected into the body using a hypodermic needle. Inside a vein, they could be steered around the body using an external magnetic field.
