Men with otherwise decent sperm counts can sometimes suffer from what's known as "low sperm motility." Their sperm, while numerous and rightly formed, don't move forward with vigor, but rather—in some sort of sad metaphor for life—shift around in a circular or sluggish manner. In short, the sperm are not able to reach their egg-target on their own, resulting in non-fertility and frustration for trying-to-conceive couples.
The standard solution today is either in vitro fertilization (where eggs are fertilized outside the body and then returned) or artificial insemination (where sperm are placed in the uterus with a medical instrument). But, in the future, there may be a third alternative: nano-motors that help sperm on their way.
Researchers at the IFW Dresden research institute, in Germany, have developed tiny helixes that wrap around sperm tails. In the presence of a nearby rotating magnetic field, the metal "spermbot" spins around, helping the swimmer to lodge itself into an egg wall. Then, once the sperm is delivered, the helix releases itself and spins in the opposite direction and away again.
So far, the idea has been tested only with bull sperm in a petri dish. And, writing up their work in the journal Nano Letters, the researchers caution that it could be some time before human clinical trials begin. For one thing, they still need to show that motors can actually fertilize eggs, not just move the sperm to its destination.
But there are plenty of researchers looking at remotely controlling nano-motors to deliver drugs and detect disease inside the body. So, the idea of mechanically assisting sperm isn't outlandish. "We have chosen magnetic helices as micromotors because of their relatively simple mechanism of motion that is widely understood and easy to control in 3-D by a common setup," the researchers say in the paper.