Researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have developed a new method to print 3D structures composed entirely of liquids by using a modified 3D printer.
The team achieved this feat by injecting threads of water into silicone oil—sculpting tubes made of one liquid within another liquid—enabling them to print threads of water between 10 microns and one millimeter in diameter, in a variety of spiraling and branching shapes up to several meters in length.
The material can also conform to its surroundings and repeatedly change shape.
“It’s a new class of material that can reconfigure itself, and it has the potential to be customized into liquid reaction vessels for many uses, from chemical synthesis to ion transport to catalysis,” Tom Russell, a visiting faculty scientist in Berkeley Lab’s Materials Sciences Division, said in a statement.
To start, the researchers developed a method to sheathe tubes of water in a special nanoparticle-derived surfactant that locks the water in place and prevents the tubes from breaking up into droplets. The surfactant—which the researchers dubbed supersoap—was achieved by dispersing gold nanoparticles into water and polymer ligands into oil.
After the water is injected into the oil, dozens of ligands in the oil attach to the individual nanoparticles in the water to form the nanoparticle supersoap. These supersoaps jam together and vitrify which stabilizes the interface between oil and water and locks the liquid structures in position.
“This stability means we can stretch water into a tube, and it remains a tube,” said Russell. “Or we can shape water into an ellipsoid, and it remains an ellipsoid. We’ve used these nanoparticle supersoaps to print tubes of water that last for several months.”
The researchers then modified an off-the-shelf 3D printer by replacing the components designed to print plastic with a syringe pump and needle that extrudes liquid. The team then programmed a printer to insert the needle into the oil substrate and inject water in a predetermined pattern.
“We can squeeze liquid from a needle, and place threads of water anywhere we want in three dimensions,” Joe Forth, a postdoctoral researcher in the Materials Sciences Division, said in a statement. “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.”
All-liquid material could pave the way for liquid electronics that power flexible, stretchable devices, as well as to chemically tune the tubes and flowing molecules through the, leading to new ways to separate molecules or precisely deliver nanoscale building blocks to under-construction compounds.