imec is Back to Film, Organic Film

imec promotes its organic film image sensors:

"We demonstrated a first film measuring 6 by 8 cm – which can check 4 fingers simultaneously – and which has a resolution of 200ppi. The second film – designed for a single fingerprint – has a resolution of 500ppi. This level of accuracy is what would be typical for the FBI to identify someone correctly.

The image sensors detect visible light between 400 and 700 nm that is reflected by the skin. They can also detect light that penetrates the skin before being reflected. This latter feature is of value for detecting a heartbeat, which provides an extra security check.

The fingerprint and palm print sensor is made up of a layer of oxide thin-film transistors with organic photodiodes on top. These photodiodes can then be ‘tuned’ by using a different organic material so that they detect a different wavelength, such as near infrared. This enables the vein pattern in a hand to be visualized, which is even more precise for accurate identification than a palm print.

In addition to this fingerprint scanner based on photodiodes and light, imec and Holst Centre are also working on a scanner that uses thermal sensors (PYCSEL project). Once again a lower layer of oxide thin-film transistors is used. The upper layer is a material that measures electric temperature changes. The fingerprint is then detected indirectly by local variations in temperature changes that correspond with the pattern of the fingerprint. Here again a resolution of 500ppi is achievable."