You can use 3D printing to make a handful of electronics, such as antennas and batteries, but LEDs and semiconductors have been elusive; you usually need some other manufacturing technique to make them work, which limits what they can do and where they’ll fit. A team of Princeton researchers recently solved this problem, however. They’ve found a way to make quantum dot LEDs using only a 3D printer.

Here’s a hypothetical question: would you rather have a head-up display on glasses or a contact lens? If you answered “contact lens”, the bad news is that you may be waiting some time. But the good news is that it just got a little more feasible, with the invention of the world’s first 3D printer that can print LEDs. The team, led by Michael McAlpine at Princeton University’s McAlpine Research Group, has successfully used its printer to 3D-print quantum dot LEDs — LEDs that are considered the next step up from OLED. QLEDs shine brighter and with purer colour, at a lower power consumption rate, using cadmium selenide nanocrystals. They’re also ultrathin, flexible and transparent — like, for instance, contact lenses. “The conventional microelectronics industry is really good at making 2D-electronic gadgets,” McAlpine said. “With TVs and phones, the screen is flat. But what 3D printing gives you is a third dimension, and that could be used for things that people haven’t imagined yet, like 3D structures that could be used in the body.”