A major cause of male infertility is the production of sperm that are unable to complete the long, arduous journey to the egg. They’re not strong swimmers.
Enter the spermbot,an invention of German scientists from the Leibniz Institute for Solid State and Materials Research and the Chemnitz University of Technology that acts like a powered-up flutterboard. Published in the American Chemical Society journal Nano Letters, their study details how the spermbot works, as well as preliminary studies of it in action.
The spermbot is a microscopic helix-shaped motor that fits around the tail of individual sperm. The head of the sperm sticks out the front and is secured by a noose-like ring.
The motor is controlled by a magnetic field to maneuver it around a sperm cell. Once the sperm are strapped in, they are directed towards their destination by rotating magnetic fields.
The spermbot was carefully designed to avoid sharp components that could kill the sperm cells.
In the nanotechnology world, micromotors often take the shape of the natural machines they aim to replace. The helix-shape of the spermbot is very similar to the sperm tail, which is used to swim.
The sperm still provide most of the propulsion with their tails, but the spermbot adds that extra oomph that the little gametes were missing.
Immotile sperm are not necessarily bad – their genetic information is often just as healthy as the information found in strong swimmers.
To ensure that the poor swimmers they captured were healthy in every other sense, the researchers used a viability test that causes the tails of healthy sperm to swell.
The researchers were able to successfully capture weak swimmers and move them towards an egg in an experimental set-up. Once the sperm had arrived at the destination, they were easily released by reversing the magnetic field that is used to rotate the spermbot.
This isn’t the first time the research group – led by Oliver Schmidt – has made the news with their robotic sperm. In 2013 they developed a rudimentary spermbot prototype by placing microscopic metal cylinders onto the heads of bull sperm, which were directed around with similar magnetic fields.
The spermbot is attractive because it has the potential to be used in vivo – sperm would be directed through the uterine cavity and oviducts to allow for fertilization inside of the human body.
Using this technology would be an attractive alternative to There would be less risk to an embryo which has to be transferred back into the uterus after culturing.
The spermbot hasn’t been perfected yet. The researchers found that the microscopic motor would often become permanently stuck to the sperm cells. As well, the researchers do not currently have a way of monitoring a spermbot as it travels through the reproductive