A group of scientists used chains of magnetic nanoparticles to control elastic polymers in three dimensions — a tool that is said to effectively control soft robots remotely.

Soft robots are flexible, and by incorporating the technique developed by North Carolina State University researchers, these devices can have a wide range of applications in different fields including biomedical industries and manufacturing processes, among others.

The Power Of Remotely Controlling Robots

The team is particularly interested in utilizing magnetic fields to manipulate the action of the robots. Through this, the devices can be controlled without physically connecting to the polymer. Aside from that, magnetic fields are widely available and can be collected from permanent electromagnets and simple magnets.

Making A Robot "Soft"

To say that a robot is "soft" means applying a magnetic field that can help experts control the bending characteristics of a magnetic polymer nanocomposite. The process is tedious and challenging, but for the scientists of the new study, they were able to make it happen.

They embedded long chains of nanoscale magnetic particles in layers of elastic polymer.

First, the researchers dispersed iron oxide nanoparticles into a solvent and added a polymer. The solution was then transferred into a mold to build the desired shape.

Next, the scientists applied a magnetic field, which caused the nanoparticles to line up in parallel chains.

Once the mixture was dried up, the chains locked into place and the finished product could then be cut to refine its shape.

Sumeet Mishra, lead author of the study and a Ph.D. student at the university, said their method can build big nanocomposites in various shapes, which can be controlled from afar.

"The nanoparticle chains give us an enhanced response, and by controlling the strength and direction of the magnetic field, you can control the extent and direction of the movements of soft robots," she said.

Simplifying The Complex

The technique is rooted from the structure of the chains. The experts also built a simple model so as to explain, in simple terms, how the interconnected nanoparticles impact the mechanical reaction in magnetic fields.

Joe Tracy, the corresponding author of the paper and an associate professor at the university, said the main idea is that nanoparticles are placed in chains and that the dipoles are aligned from head to tail. The positive side of each nanoparticle was attached to the negative side of the other throughout the chain.

An interesting concept related to this technique is the so-called magnetic anisotropy, which results from arranging nanoparticles in chains. Tracy said that when a magnetic field is infused in any direction, the chain tries its best to become as parallel as possible to the magnetic field. The only limitation identified in this reorientation is gravity and the polymer's elasticity.

Applications

The new discovery has a wide range of applications, most particularly in the medical field because soft robots that need direct electricity and light supply may be hazardous.

"Electrical control can raise safety issues for some medical applications," said Mishra. Aside from that, she said there may be signal communication issues between the devices and the body. Through their magnetic field discovery, however, effectivity and safety are more ensured.

To add to the promising future of the discovery, the researchers said the materials used in the experiment are inexpensive and easy to source. The technique is easy to do and is relatively simple, the researchers said.

The study was published in the journal Nanoscale by the Royal Society of Chemistry.