News Feature | July 26, 2016

Bio-Inspired Microrobots Shapeshift, Move With Magnets

By Suzanne Hodsden

The microbots are powered and controlled by electromagnetic fields. They shapeshift when heated by a laser. Image courtesy of EPFL.

Taking inspiration from bacteria, a team of Swiss scientists has developed a platform for developing microrobots that can be customized for various medical indications, such as delivering drugs or performing delicate surgical operations, including unblocking clogged arteries. These tiny robots shapeshift in response to heat and can be remotely controlled using electromagnetic fields.

Scientists from Ecole Polytechnique Federale de Lausanne (EPFL) and the Swiss Federal Institute of Technology (ETHZ) build each microrobot by submerging magnetic nanoparticles into hydrogel and then using electromagnetic fields to precisely place the particles throughout the robot, according to a press release.  Once finished, the entire microbot is polymerized to solidify the hydrogel, and then placed in water, where it shapeshifts according to the placement of the nanoparticles.

The resulting bots are soft, flexible, and require no electrical circuitry, but instead can be moved throughout the body using electromagnetic fields. Though the platform can be manipulated to take on a variety of shapes, the prototype presented in a study published in Nature Communications uses a flagellum to move. The flagellum retracted to wrap around the body, similar to the bacteria that causes African trypanosomiasis, otherwise known as sleeping sickness.

“We show that both a bacterium’s body and its flagellum play an important role in its movement,” said EPFL scientist Selman Sakar, who teamed with Hen-Wei Huang and Bradley Nelson at ETHZ for the study. “Our new production method lets us test an array of shapes and combinations to obtain the best motion capability for a given task.”

In the study, researchers explain that the platform allows for extremely versatile and rapid prototyping based on the specific needs of an intended indication, and the use of magnetic fields allows for very subtle changes in the device’s motility. According to Sakar, the research has shed valuable light on how bacteria move around inside the body and adapt to changes in their environments.

Researchers acknowledged that the research still is in its earliest stages, and they have yet to test the technology in a living body. Future research, said Sakar, will be testing for safety to ensure that the microbots cannot cause dangerous side effects.

Scientists at MIT recently introduced a similar origami-like design for an ingestible robot, but on a much larger scale. Their small device was designed specifically to retrieve button batteries, thousands of which are swallowed by children every year. The MIT device was likewise manipulated using heat and magnets.

Drexel University scientists may have found an alternative to traditional stenting and angioplasty with tiny corkscrew-like robots that can drill through blockages and restore blood flow. These millirobots, said their creators, are completely biocompatible and dissolve once their task is completed.

Many researchers believe that robotic pills may be the answer for delivering large molecule biologic medications, such as insulin, into the body. Because of their organic make-up, current biologics must be delivered through injection, a method that is not always convenient or possible for patients.  Vanderbilt scientists recently open-sourced their robotic pill platform with hopes of expediting this research.