Printable organic photodiodes are intended to support a new generation of portable and rugged fingerprint readers capable of performing biometric scans in difficult lighting conditions.
French pioneer of organic printed electronics Isorg has obtained FBI personal identity verification certification for its Isorg-Bio11 direct-scanning capture device, based on organic photodiodes. Isorg’s FAP 10 module, capable of scanning one finger, is now FBI approved for identity security applications with mobile devices, such as access control at airports.
Isorg plans to expand its organic photodiode technology to larger fingerprint modules, as the company upgrades to a four-finger FAP 60 device and possibly palm sensing to scan an entire hand.
Organic photodiodes
Fingerprint readers rely on photodiodes to convert light into electric current. Photodiodes are traditionally made from silicon, which means standard fingerprint readers are bulky, heavy, and fragile.
New organic photodiodes are based on organic materials, such as dyes or pigments. These can be printed on a flexible TFT (Thin Film Transistor) backplane, using inkjet printing techniques, to create lightweight sensors.
The result is a smaller, lighter and less fragile fingerprint reader module that is less than 2 millimeters thick. They are cheaper to produce than silicon photodiodes, with less environmental impact.
The limitations of silicon photodiodes mean that fingerprint readers are typically only deployed as fixed installations, such as airport passport control or building access control. Organic photodiodes enable the construction of portable fingerprint readers that can be used by mobile security patrols and field officers.
Another key benefit of using organic photodiodes is that they are resistant to wet or dry fingers and perform best in difficult lighting conditions such as direct sunlight or bright indoor lights. These advantages also make them better suited for mobile use than traditional fingerprint readers.
The desire to manufacture photodiodes in the French manufacturing plant of Isorg in Limoges, rather than sending the work elsewhere, has also been a key factor in the development of organic photodiodes technology which does not require conditions of high temperature vacuum manufacturing, explains Nicolas Bernardin, Isorg Business Development Director. In addition to being simpler and more cost effective, the use of organic photodiodes allows Isorg to print on large substrates measuring 780 by 650 millimeters.
FBI Certification and Beyond
Obtaining FBI certification is an important step for the use of organic photodiodes in fingerprint readers for security applications, says Bernardin.
“This certification is the culmination of six months of hard work to comply with FBI technical requirements. This is a major step that allows us to sell our technology on the security and identification market.
To support customer product development, Isorg will provide a reference design with its latest integrated ROIC (Read Out Integrated Circuit), as well as software processing for image quality improvement.
Beyond security, Isorg’s flexible organic photodiode sensors have applications in secure voting, medical devices, IoT and consumer electronics.
At the Consumer Electronics Show 2020 in Las Vegas, Isorg presented the first smartphone equipped with a full-screen biometric sensor to scan fingerprints.
“Unlike traditional fingerprint readers for smartphones, this technology allows smartphones to scan four fingerprints when they access sensitive data such as medical records or authorize the transfer of large sums of money. Our organic photodiode technology facilitates fingerprint scanning in a wide range of situations to improve security. “
