The researchers built the system by first designing a light-sensing chip, which features a pattern of evenly spaced photodetectors. This was then fabricated at a commercial semiconductor manufacturing facility. A wafer containing multiple chips was then placed in a deposition chamber, where layers of organic material were deposited in between the photodetectors. These layers make up the organic light-emitting diodes, or OLEDs, that create the display. The mosaic of photodetectors and OLEDs is then encapsulated in a thin polymer film to protect it.
The idea of integrating OLEDs with a photodetector chip is intriguing, says Sawchuk. “There are a lot of challenges in building wearable displays for the applications [intended by the researchers], and any advances in this field are very exciting,” he says.
The Fraunhofer IPMS researchers will demonstrate their prototype at the Society for Information Display conference in San Antonio this week. The current version touts a simple monochromatic display–about 1.25 centimeters on each side, with a resolution of 320 by 240 pixels. Scholles says that full-color displays are possible but trickier to create because they require adding color filters to white OLEDs, which are difficult to make efficiently and aren’t always reliable. However, the team at Fraunhofer IPMS has partnered with Novaled, an OLED company that manufactures high-quality white diodes, and plans to make future color prototypes using the company’s diodes.
The camera in the researchers’ current prototype is still fairly rudimentary. It has a resolution of only 12 pixels, which means that it can’t yet track a user’s eye movements. However, Scholles says that the team has developed a 160-by-120-resolution version of the camera chip that has been tested in the lab, but not yet integrated with a display. The researchers expect to have an advanced version of the system, complete with higher-resolution camera and full eye-tracking capability, by early 2011.