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Identifying fingerprints by a PYCSEL sensor

Biometric sensors for personal identification undergo a huge evolution since a few years. The expansion of this market will need low costs and convenient and easy-to-integrate technologies, both aspects answered by the European collaboration PYCSEL. The objective is to develop a flexible fingerprint sensor on plastic, building on the expertise from the CEA, the coordinator of PYCSEL, on this sensor technology in collaboration with 7 European key-partners.

Published on 10 April 2018

The fingerprint sensors bottlenecks

Nowadays, from governmental application and building access control to basic consumer electronics, as smartphones and laptops, fingerprint sensors are ubiquitous. Basically, those rely on two main technologies and can be based on:
  • Prism-based optical sensors, a robust and mature technology, which enables a high acquisition/high resolution surface at a reasonable price, and allows capturing multiple fingerprints concurrently, but caring some limitations. Such sensors are heavy, thick, bulky, non-conformable and can raise concerns regarding integration, product design or portable uses.
  • Silicon based sensors, comprising capacitive, pressure or thermal devices, are small and easy to integrate to consumer electronics, but only if a small sensing area is required. 

Benefiting of the CEA’s experience on printed electronics

CEA-Liten, the CEA institute coordinating PYCSEL, has been deeply involved for over a decade in the development of printed electronics for creating smart surfaces. The CEA printing platform called “PICTIC”, supported by European Regional funds ERDF and the Rhône-Alpes region, develops smart plastics, papers and textiles produced by printing electronic functions directly on flexible large area (320 x 380 mm) surfaces. Opened to industrial partners, especially SMEs and start-ups, PICTIC fosters printed electronics products to enter the market. The platform is designed to scale up printed devices from laboratory level TRL3-4 to products prototypes TRL 6-7. The portfolio of CEA organic printed devices is large going from sensors and actuators, photodiodes, to transistors for backplane and logics. From functionalized surfaces for the dashboards of automotives to smart patches for well-being and health monitoring, the scope of application is broad. Another CEA Institute, Leti, pioneer in micro and nanotechnologies, is also involved in PYCSEL.

Flexible electronics yet with high resolution

PYCSEL will address the bottlenecks of current fingerprint identification systems using flexible electronics (also called ‘Thin and Organic Large Area Electronics’ (TOLAE)) technology. These thin conformable large-area sensors present the advantage:
  • To be free of form factor constraints during integration;
  • To show enhanced ergonomics in future innovative cost-efficient fingerprint identification systems while enabling large area/high resolution acquisition. 

A new PYCSEL fingerprint sensor

For this purpose, PYCSEL project will develop a new fingerprint-sensing surface combining a printed pyroelectric organic sensor with an active TFT (Thin Film Transistor) matrix array on a plastic flexible foil. The final PYCSEL prototype, a large area fingerprint sensor, will enable acquisition up to four fingers at a time, with a challenging objective of 500 dpi resolution.
Among other things, it will require developing a manufacturable process for a 500 ppi TFT backplane and a reliable fingerprint pyroelectric sensor, compliant with the 500 ppi high resolution requirements,including encapsulation (mechanical protection and shielding) and specific sensor poling methods.
Example of flexible printed electronics developed at the CEA. © CEA/ V. Guilly

A growing biometrics market

Moving flexible and wearable electronics to a next level of applications addressing the growing worldwide biometrics market is the ambition of PYCSEL. “Historically, a governmental then company and consumer market, the biometrics market is expected to be worth more than 20 billion € by 2020”, explains Audrey Martinent (CEA), coordinator of PYCSEL. “As biometric identification becomes increasingly important, our technologies will increase fingerprint sensors penetration into a large range of applications.” The project is expecting impact for example in high volume automotive (personalized HMIs1, machine tool (user-restricted HMI), buildings (access control) and consumer electronics.
1 HMI means « Human-Machine Interface».


Logo PYCSEL V9.jpgLaunched in January 2017, PYCSEL is bringing together for three years, and under the coordination of the CEA, 8 different high skilled partners from 6 European countries (CEA, IDEMIA, IRLYNX, IMEC, TNO, UC3M, AUTOLIV and BIOAGE SRL). Granted with 3.8 M € from the EU, the project will develop a new and improved fingerprint sensor. While being thin and flexible, it will cover a large area with a high resolution of 500 ppi and at low cost.

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