Why Sperm Cells Make Such Great Microbots

Controlling cells is no easy thing, but it’s something science has had its eye on for some time. So far, efforts have had intriguing results — a six years ago, scientists got bacteria to motor beads using chemicals to control the movement of their flagella — the whip-like tails they use to propel themselves. While seemingly curious, the potential applications for harnessing the power of microorganisms is immense: they could be used to deliver drugs to specific parts of the human body, for instance.

Recent advances are even more compelling — in Germany, a team of researchers have been using sperm cells from bulls to develop their micro-bio-bots. These “spermbots,” developed in the Institute for Integrative Neurosciences, integrate microtubes made of iron and titanium to the sperm. The tubes are slightly bigger on one side than the other, causing individual sperm to become trapped inside them head-first with their long tails free, which enables locomotion in a direction manipulated by magnetic fields.

This video from NewScientist beautifully illustrates the process:

Though surprising to many outside the field, sperm are a great option for the development of this type of technology, as they can travel through viscous fluid easily (to get an idea of how important this adaptation is, check out Aatish Bhatia’s explanation on the physics of sperm cells. It’s a very accessible YouTube video, you’ll love it, I swear) and they’re harmless to the human body.

“The combination of a biological power source and a microdevice is a compelling approach to the development of new microrobotic devices with fascinating future applications,” the authors write in their paper, which appeared in the September issue of Advanced Materials.