Researchers at the National Institute of Standards and Technology (NIST) have developed a new method of 3D-printing gels and other soft materials. Published in a new paper, it has the potential to create complex structures with nanometer-scale precision. Because many gels are compatible with living cells, the new method could jump-start the production of soft tiny medical devices such as drug delivery systems or flexible electrodes that can be inserted into the human body.

A standard 3D printer makes solid structures by creating sheets of material — typically plastic or rubber — and building them up layer by layer, like a lasagna, until the entire object is created.

Using a 3D printer to fabricate an object made of gel is a “bit more of a delicate cooking process,” said NIST researcher Andrei Kolmakov. In the standard method, the 3D printer chamber is filled with a soup of long-chain polymers — long groups of molecules bonded together — dissolved in water. Then “spices” are added — special molecules that are sensitive to light. When light from the 3D printer activates those special molecules, they stitch together the chains of polymers so that they form a fluffy weblike structure. This scaffolding, still surrounded by liquid water, is the gel.