Inspired by sperm, tiny robots could deliver drugs

These microscopic machines could bring cancer drugs to diseased cells

Minuscule robots of the future that swim around in your body delivering drugs have come a step closer to reality.

Meet MagnetoSperm. They're infinitesimal robots that squirm around just like sperm and reach parts of the body that are difficult to access.

Developed by researchers in the Netherlands and Egypt, MagnetoSperm robots navigate using weak oscillating magnetic fields.

With polymer bodies and cobalt-nickel heads, the robots are 322 micrometers long, about the size of a house dust mite, and have a shape similar to sperm cells.

The magnetic head allows the robot to align itself along weak magnetic fields, according to research published in Applied Physics Letters by scientists from the University of Twente in the Netherlands and German University in Cairo.

The magnetic fields have a strength of less than 5 milliTeslas, which is about the power of a refrigerator magnet.

When the robot aligns itself, it generates thrust along its flexible body, moving forward as it wriggles. It can move at speeds around 160 micrometers per second, and can be steered using the magnetic fields.

The robot could be driven around vessels ranging from arteries to capillaries, the researchers said.

"The applications of this micro-robot are diverse," Sarthak Misra, an associate professor of robotics and mechatronics at the University of Twente and one of the authors of the paper, wrote in an email. "These include targeted drug delivery, in vitro fertilization, cell sorting and cleaning of clogged arteries, among others."

MagnetoSperm isn't the only mini-robot that takes its design cues from sperm.

Last year, German researchers writing in Advanced Materials described a "biohybrid micro-robot" built by capturing bovine sperm cells in magnetic microtubes.

While the cells' own whip-like tails provided the propulsion, the metallic microtubes could be guided using magnetic fields, potentially allowing such miniature devices to guide sperm to eggs or drugs to specific sites.

The disadvantage to that approach is that the coupling between sperm and microtube happens randomly, the MagnetoSperm researchers said.

They plan to further shrink the MagnetoSperm bots by equipping them with nano-fibers that would serve as flagella. They are also working to synthesize drug payloads for the robots that could be released near diseased cells.

"This would allow us to achieve targeted therapy to mitigate the negative side effects of conventional chemotherapy," wrote Islam S.M. Khalil, an assistant professor in the Faculty of Engineering and Material Science at German University in Cairo who co-authored the MagnetoSperm paper.

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