Sperm cells are weird. They move around like a swarm of flies, blindly looking for an egg to connect with. It turns out, however, that the spastic, tail-whipping power of sperm can be useful for other things. In a report published in the journal Applied Physics Letters, scientists have learned how to mimic the movement of sperm with tiny magnetic robots, and are hoping to use them to transport drugs and other small things through the body. The name they gave the robots: MagnetoSperm.

“As technology progresses and many products get smaller, it becomes difficult to assemble objects on nano- and micro-scales,” said co-author of the report Islam Khalil, a post-doctoral researcher at the Department of Robotics and Mechatronics at the University of Twente in the Netherlands, in a press release. “MagnetoSperm can be used to manipulate and assemble objects at these scales using an external source of magnetic field to control its motion.”

The 322 micron-long robots were created by Khalil and his team, and look almost exactly like sperm, with a head coated in a thick layer of cobalt-nickel and an uncoated tail. When it’s subjected to a magnetic field about the strength of a refrigerator magnet, the torque on its head forces the tail to oscillate, subsequently moving it forward.

“Nature has designed efficient tools for locomotion at micro-scales,” said Dr. Sarthak Misra, principal investigator of the study and an associate professor at the university, in the press release. “Our micro-robots are either inspired from nature, or directly use living microorganisms such as magnetotactic bacteria and sperm cells for complex micro-manipulation and targeted therapy tasks.”    

During a time when implantable devices are being fitted and developed for permanent placement — they currently need to be replaced every 10 years or so — the MagnetoSperm may be useful for minor tweaks in the hardware, along with other uses, such as drug delivery, in vitro fertilization, cell sorting, and the cleaning of clogged arteries.

In April, a report in Advanced Functional Materials detailed robots made of magnetic rods, which would also function to assemble materials within the body. But the robots lacked a propulsion system. Khalil’s work builds on this, providing the robots with tails, or flagella, which can move at 0.5 body lengths per second, the report says.

If technologic advancements can continue moving at this pace, we may soon have the ability to treat conditions in a new, vastly improved way.


Source: Khalil I, Dijkslag H, Abelmann L, Misra S. MagnetoSperm: A microrobot that navigates using weak magnetic fields. Applied Physics Letters. 2014.