Synaptics unveiled a new fingerprint sensor called Clear ID that can be placed under the OLED display of a smartphone and can be used to unlock a device in under seven milliseconds - on par with regular fingerprint sensors.

The Clear ID sensor can be placed under any part of the OLED screen (which will have to direct the user to place the fingerprint in the right location). Clear ID works with both rigid and flexible OLEDs - and can even work underwater and on displays that are covered with a screen protector.

Sonavation announced a new technology that enables to embed an ultrasound fingerprint sensor behind an OLED display. Using this solution, mobile phone makers could enlarge the display area of the mobile device, as there will no no need for a separate fingerprint sensor.

Sonavation says that their "3D biometric ultrasound technology" is the only fingerprint authentication solution that offers complex-enough imaging through a full stack display.

Peratech announced an innovative new touch screen technology for OLED displays. The QTC Ultra Sensor is a pressure-based touch technology, that is applied behind the display. Regular touch layers are transparent films placed in front of displays, which reduce the light output (brightness). This new sensor is accurate, low on power and supports multi-touch and can also sense the amount of pressure.

Pertech says that the new sensor can be used for OLED and e-paper displays, as these can actually be pressed (unlike LCD panels, in which pressing them is not advisable). It doesn't have a to be a flexible OLED, it works behind glass - and a deflection of a micron or so all that is needed for QTC Ultra to sense the touch.

Update: Microsoft removed the video that shows the transparent OLED...

Transparent OLEDs are exciting (and Samsung wants to tap that market) - but a lot of people wonder what is it really good for? Microsoft is showing a nice concept: using a camera beneath a transparent OLED to create gesture-based UI. The camera "sees-through" the OLED:

Microsoft are using a Samsung-made transparent AMOLED panel.