Printing all-liquid 3D structures

Berkeley Lab

A TEAM of scientists has developed a method to 3D print all-liquid structures which could have applications in flexible electronics and chemical synthesis.

The team modified an off-the-shelf 3D printer by replacing the components designed to print plastic with a syringe pump and a needle. The printer was then programmed to insert the needle into oil and inject threads of water in a predetermined pattern to create structures made entirely of liquids. The threads of water become tubes that can be between 10 µm and 1 mm in diameter and can be made into various spirals and branches several metres in length.

The structures could be used to construct liquid electronics, deliver nanoscale building blocks to compounds under construction, or separate molecules. “It’s a new class of material that can reconfigure itself, and it has the potential to be customised into liquid reaction vessels for many uses, from chemical synthesis to ion transport to catalysis,” said Tom Russell, a visiting faculty scientist in Berkeley Lab’s materials sciences division.

The tubes of water are prevented from breaking up into droplets by using a nanoparticle-derived surfactant which they call a nanoparticle “supersoap”. The supersoap was created by dispersing gold nanoparticles into water and polymer ligands into oil which then bind at the interface between the two liquids, creating an elastic particle layer that stabilises the shape of the water tube.

“This stability means we can stretch water into a tube, and it remains a tube. Or we can shape water into an ellipsoid, and it remains an ellipsoid,” said Russell. “We’ve used these nanoparticle supersoaps to print tubes of water that last for several months.”

 “We can squeeze liquid from a needle, and place threads of water anywhere we want in three dimensions,” said Joe Fort, a postdoctoral researcher at Berkeley Lab. “We can also ping the material with an external force, which momentarily breaks the supersoap’s stability and changes the shape of the water threads. The structures are endlessly reconfigurable.”

Advanced Materials http://doi.org/gc8h4s