When it comes to moving simply but effectively through a liquid medium, few things are as good as sperm. This fact isn't lost on scientists, who have built tiny sperm-like robots (or even used "hijacked" sperm) in efforts to create new methods of targeted drug delivery, among other potential applications. The latest such endeavor has resulted in a batch of microrobots known as MagnetoSperm.

The robots were created by scientists at the University of Twente in the Netherlands, and the German University in Cairo, located in Egypt.

Measuring just 322 microns long, each one consists of a silicon support wafer covered in a layer of SU-8, which is a polymer known for its mechanical stability and ease of fabrication. While their tails (or flagella) are left bare, the robots' heads are coated with a layer of cobalt-nickel.

When subjected to an oscillating magnetic field roughly equivalent to that emitted by a decorative fridge magnet, magnetic torque on the head causes it move back and forth. This in turn causes the flagellum to oscillate, propelling the robot forward. By angling the line of the magnetic field, it's possible to steer the MagnetoSperm toward a target.

The team is now working on making the robots even smaller, and possibly replacing their flagella with ones made from a better-performing magnetic nanofiber. Along with drug delivery, it is hoped that they could ultimately also be used for applications such as cell sorting, in vitro fertilization, and the cleaning of clogged arteries.

A paper on the research was recently published in the journal Applied Physics Letters.