Princeton researchers 3D print light-emitting contact lens

11 Dec 2014

Lead project researcher Michael McAlpine with the 3D-printed electronic contact lens. Photo by Frank Wojciechowski

A team of researchers at Princeton University have 3D printed a contact lens fitted with electronics which enable it to beam projections of coloured light, just to show they can.

The hard plastic contact lens is embedded with nanoparticles known as quantum dots. These tiny crystals create the light-emitting diodes (LEDs), with different-sized dots used to generate different colours.

“We used the quantum dots as an ink,” said lead researcher Michael McAlpine, assistant professor of mechanical and aerospace engineering at Princeton.

“We were able to generate two different colours, orange and green.”

3D printing diverse materials

While X-Men fans might be excited by the prospect of doing a convincing Cyclops impression, McAlpine stressed the lens is not designed for actual use (for starters, it requires an external power supply). Rather, it has been develop to demonstrate the possibilities that 3D printing can bring to electronics.

“We were able to 3D print an entire device, in this case a LED,” said McAlpine. “This shows that we can use 3D printing to create complex electronics, including semi-conductors.”

The Princeton team’s latest development is part of an ongoing effort to use 3D printing to assemble active electronics using diverse materials. This is particularly complex as the mix of materials may be mechanically, chemically or thermally incompatible. That is to say, the heat required to shape one material could destroy another in proximity.

A custom 3D printer was built for the job, which McAlpine estimated to cost around US$20,000.

No stranger to merging electronics with vastly different materials, McAlpine was also part of a team who created a bionic ear out of living cells, which had an embedded antenna that could receive radio signals.

Applications in medical-device production

One of the advantages of 3D printing over traditional electronics manufacturing is that circuits don’t have to be built in flat assemblies, as 3D printers can create vertical structures as easily as horizontal ones.

“In this case, we had a cube of LEDs,” said McAlpine. “Some of the wiring was vertical and some was horizontal.”

However, McAlpine doesn’t see 3D printing as a replacement for traditional manufacturing, moreso an enhancement.

Traditional methods still have the advantage of speed and efficiency when it comes to creating multiple copies of electronic components with high reliability, whereas 3D printing is slow but easy to change and customise. This method can be best applied to medical devices, where devices need to be custom-fitted to patients or where unusual materials need to be combined in a customised way.

The research has been supported by the US Air Force Office of Scientific Research and the Defense Advanced Research Projects Agency (DARPA).

Elaine Burke is the host of For Tech’s Sake, a co-production from Silicon Republic and The HeadStuff Podcast Network. She was previously the editor of Silicon Republic.