A group of engineers have tapped into magnetic fields to better control soft robotic devices.

A team from North Carolina State University have remotely manipulated micro-particle chains embedded in soft robotic devices as a way to make a fundamental advance in controlling the robots.

“By putting these self-assembling chains into soft robots, we are able to have them perform more complex functions while still retaining relatively simple designs,” Joe Tracy, an associate professor of materials science and engineering at North Carolina State University and corresponding author of a paper on the work, said in a statement.

“Possible applications for these devices range from remotely triggered pumps for drug delivery to the development of remotely deployable structures,” he added.

The new technique builds on previous research in the field of self-assembling, magnetically actuated composites by Tracy and Orlin Velev, the INVISTA Professor of Chemical and Biomolecular Engineering at NC State.

In this study they introduced iron microparticles into a liquid polymer mixture and then applied a magnetic field to induce the microparticles to form parallel chains. They then dried the mixture, leaving behind an elastic polymer thin film embedded with the aligned chains of magnetic particles.

“The chains allow us to manipulate the polymer remotely as a soft robot by controlling a magnetic field that affects the chains of magnetic particles,” Tracy said.

The direction of the magnetic field and its strength can be varied and the chains of iron microparticles respond by aligning themselves and the surrounding polymer in the same direction as the applied magnetic field.

By using this technique, the researchers created three kinds of soft robots—a cantilever that can lift up to 50 times its own weight, an accordion-like structure that expands and contracts, mimicking the behavior of muscle, and a tube that is designed to function as a peristaltic pump where a compressed section travels down the length of the tube.

“We’re now working to improve both the control and the power of these devices, to advance the potential of soft robotics,” Tracy said.

The researchers have also developed a metric for assessing the performance of magnetic lifters including the cantilever device.

“We do this by measuring the amount of weight being lifted and taking into account both the mass of particles in the lifter and the strength of the magnetic field being applied,” Ben Evans, co-author of the paper and an associate professor of physics at Elon University, said in a statement. “We think this is a useful tool for researchers in this area who want to find an empirical way to compare the performance of different devices.”

The study was published in ACS Applied Materials & Interfaces.