Scientists Create Method To Print Magnetic Liquid Droplets

Magnets are widely used today for all sorts of scenarios from medical devices to storing data inside computers. The thing that magnets have in common is that they are made of solid material. Scientists at Berkley Lab have created a new type of magnet that is a liquid. Researchers say that the new liquid magnets could lead to printable liquid devices for multiple applications from targeting cancer therapies to flexible liquid robots that can change shape depending on their surroundings.

The team has created a material that is liquid and magnetic of a sort that hasn't been observed before, according to researcher Tom Russell. Russell is the head of a program called Adaptive Interfacial Assemblies Towards Structuring Liquids. Russell and lead author for the study, Xubo Liu, came up with the idea of forming liquid structures from ferrofluids.

A ferrofluid is made from solutions of iron-oxide particles that become strongly magnetic in the presence of another magnet. The team used a 3D printing technique created by another researcher in the lab. Using that technique, the team was able to print 1mm droplets from a ferrofluid solution containing iron-oxide nanoparticles 20nm in diameter. That is the average size of an antibody protein.

The team says that using surface chemistry and sophisticated atomic force microscopy techniques, they found that the nanoparticles formed a solid-like shell at the interface between the two liquids using a phenomenon called "interfacial jamming." To make the particle magnetic, the team placed the droplets by a magnetic coil solution, and the magnetic coil pulled the nanoparticles towards it.

When the magnetic coil was removed, the team says the droplets gravitated towards each other. The droplets had become permanently magnetic. The researchers say that before their work, people assumed magnets could only be made from solids. The work has potential use in medicine and robotics according to the team.