There are instructions online for 3D printers that can be built by anyone, and these kits "print" using various media such as plastics, food substances, or liquids that solidify after printing. "We are trying to explore a different technology; we are working on using electrophotography to print with powders," says Rojas. "Other techniques use powders but need some sort of glue. Laser printers use powders which don't need to be suspended in liquid and so we are working to use particles that fuse together, which means they don't require a binding agent."
The exploration of this technology means Dr. Rojas and his team might one day be able to print objects using materials such as ceramics or metals. "So far we are in the beginning stages," says Rojas. Because 3D printers work by layering material from the bottom up, microscopic surface defects —such as holes or bumps— in hundreds of layers can build up, causing major surface defects in the printed object. Without solving this issue, says Rojas, the technology cannot go much farther. So his research has revolved around avoiding such defects. "Microscopic bumps on hundreds of layers can really show up, so we are investigating ways of sensing the surface layer by layer as an object is being built."
Are some materials more susceptible to defects than others? Rojas explains that so far he has only tried printing with toner that consists of tiny five-micron particles. "We are using toner because that is what was available to us. We have seen other people using thirty-micron particles, but all materials are susceptible. Larger particles might not bring more defects, but they might be visible earlier in the printing process."
Alvaro Rojas came to RIT in 2006 from Colombia on a scholarship to earn his master's degree in Industrial Engineering. He earned a second master's degree, in Systems Engineering, at the University of Illinois at Urbana-Champaign; he then returned to RIT for his PhD. He successfully defended his dissertation in the fall of 2013 and earned his doctorate. He has now traveled home to Cali, Colombia, where is on the faculty at Universidad Autonoma de Occidente. Dr. Rojas also plans to continue collaborating with his advisor, Marcos Esterman.
"I am looking forward to it and I love to teach, but I have mixed feelings because I love RIT and this will be a big change."