Image sensors go organic


LONDON - Isorg SA, a 2010 startup company that can print organic optoelectronic sensors, has teamed up with electronics display developer Plastic Logic Ltd. to develop what they claim is the world's first conformable organic image sensor on a plastic substrate.

Isorg (Grenoble, France), a spin-off from the CEA-Liten research organization, started out making single- or few-element organic sensors for use in presence and gesture detection. (see Printed sensor startup preps pilot line). Plastic Logic (Cambridge, England) has experience building organic active-matrix backplanes for conformable displays of up to millions of pixels. The two companies therefore have complementary experience and skills sets to produce a conformable image sensor.

With conformable AMOLED displays becoming a key area of interest for the production of curvilinear electronic equipment, such as novel designs of mobile phones, the ability to produce image sensors on the same substrate is clearly of interest.

The collaboration is based on the deposition of organic printed photodetectors, pioneered by Isorg onto a plastic organic thin-film transistor backplane, developed by Plastic Logic, to create a flexible image sensor. The first example has 94 by 95 pixels on a 4-cm by 4-cm active area. The pixels are 175-micron wide with a 200-micron spacing and arranged on a 375-micron pitch.

A typical Isorg organic photodetector material is PEDOT-PSS (polythylenedioxythiophene mixed with polystyrenesulfonate). It has the advantage that it can be processed in solution on to low-cost plastic or glass substrates under ambient air and ambient temperature conditions rather than using expensive vacuum and high temperature processes.

Plastic Logic optimized the backplane design, production process and materials to meet Isorg's requirements, Isorg said. The result is a flexible transmissive backplane that opens up a range of applications based around digital image sensing. Isorg listed the following possibilities: smart packaging and sensors for medical equipment and biomedical diagnostics, user identification by fingerprint scanning and 3-D interactive user interfaces for consumer electronics.

"We are extremely pleased to showcase our disruptive photodiode technology in a concrete application for imaging sensing. The ability to create conformal and large area image sensors, which arealso thinner, lighter and more robust and portable than current equipment is of increasing importance, especially in the medical, industrial and security control sectors," said Jean-Yves, Gomez, CEO of Isorg, in a statement.

In the same statement Indro Mukerjee, CEO Plastic Logic said: "I am delighted that Plastic Logic can now demonstrate the far-reaching potential of the underlying technology. Our ability to create flexible, transmissive backplanes has led us not only to co-develop a flexible image sensor, but is also key to flexible OLED displays as well as unbreakable LCDs." Organic image sensor on a plastic substrate. Source: Isorg

The first mechanical samples will go on show at the LOPE-C organic and printed electronics event in Munich, Germany, which take place June 12 and 13. Isorg did not indicate why mechanical but not electronic samples are being demonstrated.

Isorg as industrialized its manufacturing process using a pilot line in Grenoble and plans mass production volumes for the end of 2014 at a manufacturing unit in the Grenoble area. Isorg was first included in the EE Times Silicon 60 in version 11.0 in April 2011.

Peter Clarke