An optical fingerprint sensor integrates an OLED microdisplay as a light source on a microchip along with photodiodes. With the technology developed at Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology, Germany, objects can be illuminated and at the same time the reflected light can be detected and analyzed.
The microdisplays can be incorporated into interactive data eyeglasses as a “bi-directional microdisplay”: the tiny display projects the information for augmented-reality applications while the camera function detects the viewing direction – thus the content can be controlled by eye-movements.
The fingerprint sensor exploits this bidirectional functionality of light emission and detection as well. The finger is illuminated and the reflected light is detected and analyzed.
The researchers used an extra-thin encapsulation for the chip of this fingerprint sensor. As a result, the distance between finger and image sensor is minimized and the fingerprint is accurately captured Additional imaging optics are not needed for this application.
The first prototype has a native resolution of 1600 dpi, three times more than typically required by the FBI. This high spatial resolution enables identification of the smallest sweat pores beside the typical papillary lines, which can be used to increase security.
A promising application of this sensor is user verification in mobile devices. The devices are much less vulnerable to so-called spoofing (the manipulation by “false fingers”) due to their high resolution relative to conventionally used capacitive fingerprint sensors.
The researchers will present at SID Display Week 2017, May 23-25 2017 in Los Angeles, California.