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Surgery Without Cuts or Incisions: The Future is Now

Surgery Without Cuts or Incisions: The Future is Now
August 12
13:21 2016

Scientists have long searched for a way to perform delicate surgeries inside the human body without making cuts and incisions. Engineering Professor MinJun Kim, PhD and his team of researchers at Drexel University may have just taken us a little closer to reaching that goal.

Drexel engineers have been studying microrobots for decades, with the ultimate goal of creating a robotic chain that can travel throughout the human body, breaking apart at a specific location to deliver medicine or a specific treatment.

In a paper published recently in Nature Scientific Reports, Drexel Fellow U Kei Cheang, PhD describes how the team uses a rotating magnetic field to successfully move chains of tiny magnetic bead-like robots through a microfluidic environment.

These robotic chains are called “microswimmers,” and the team’s findings are a huge step forward in using the tiny bots to perform surgery and deliver medicine inside the human body.

“We believe microswimmer robots could one day be used to carry out medical procedures and deliver more direct treatments to affected areas inside the body,” explains Cheang. “They can be highly effective for these jobs because they’re able to navigate in many different biological environments, such as the blood stream and the microenvironment inside a tumor.”

One of the team’s most exciting findings is that longer robotic chains can swim faster than the short ones. The team’s 13-bead chain was able to reach an impressive speed of 17.85 microns per second.


The microswimmers move by spinning, sort of like a screw, in tandem with a rotating magnetic field outside the body. The faster the magnetic field rotates, the faster the screw-like chains are able to move.

This unique propulsion system is also how the team was able to split the chains into shorter segments. At a certain speed of rotation, the microswimmer chain will break into two smaller segments than can each move independently.

“To disassemble the microswimmer we simply increased the rotation frequency,” says Cheang. “For a 7-bead microswimmer, we showed that by upping the frequency 10-15 cycles the hydrodynamic stress on the swimmer physically deformed it by creating a twisting effect which lead to disassembly into a 3-bead and 4-bead swimmer.”

Once separated, the magnetic field can be tweaked to manipulate the 4- and 3-bead chains independently. Because the microswimmers are magnetized, they can eventually link back up to form a single chain. The Drexel team has also determined the optimal rotation speed and angle of approach to re-link the magnetic chains. This discovery is a key factor of a larger project involving 10 institutions from around the world to create microswimmer technology to perform minimally invasive surgery on arteries.

“For applications of drug delivery and minimally invasive surgery, future work remains to demonstrate the different assembled configurations can achieve navigation through various in vivo environments, and can be constructed to accomplish different tasks during operative procedures,” writes Cheang. “But we believe that the mechanistic insight into the assembly process we discussed in this research will greatly aid future efforts at developing configurations capable of achieving these crucial abilities.

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April Kuhlman

April Kuhlman

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