Scientists at EPFL have developed a 3D printing method that “grows” metals and ceramics directly from within a water-based gel, creating stronger, denser, and more intricate materials for use in energy, biomedical, and sensing technologies.
Conventional vat photopolymerization, which is used to harden light-sensitive resins layer by layer, has long been limited to polymers. Many attempts to convert these polymers into tougher metals and ceramics have not yet been successful. “These materials tend to be porous, which significantly reduces their strength, and the parts suffer from excessive shrinkage, which causes warping,” said Daryl Yee, head of the Laboratory for the Chemistry of Materials and Manufacturing (ALCHEMY) in EPFL’s School of Engineering.
Yee’s team addressed this challenge by flipping the process. Their innovation is described in a recent publication in Advanced Materials. Instead of infusing metal precursors before printing, they first printed a hydrogel scaffold, then soaked it in metal salts that are chemically transformed into nanoparticles. Repeating these “growth cycles” creates dense composites that become solid metal or ceramic structures once heated.
“Our work not only enables the fabrication of high-quality metals and ceramics with an accessible, low-cost 3D printing process; it also highlights a new paradigm in additive manufacturing where material selection occurs after 3D printing, rather than before,” said Yee.
Tests of complex iron, silver, and copper gyroids demonstrated how the new materials could withstand 20 times more pressure, only shrinking 20%, which is a significant difference from the 60 to 90% shown with older techniques. The team is now automating the process to accelerate it. “We are already working on bringing the total processing time down by using a robot to automate these steps,” Yee concluded.
