Compared to traditional electronic solutions, printed electronics offers several differentiating factors which make them particularly well suited to sensing application. Most printing processes are compatible with large area substrates, which enable the design of large area sensors with sensing capabilities across surfaces of up to 500x500mm. This at a very competitive cost per area ratio (compared to amorphous silicon or CMOS technologies).
A pioneer in printed electronics applied to optical sensors, Isorg addresses several markets and functionalities. This includes scanning surfaces for X-ray
digital imaging with the co-integration of organic photodiodes with transistors on amorphous silicon, photodiodes combined with organic transistors on
In the future, substituting amorphous silicon technology with organic electronics will increase cost competitiveness and enable new products developments
(for lighter and more robust portable equipment).
The first demonstrator of such a full organic image sensor is being fabricated as a collaborative development between Isorg and Plastic Logic. More particularly, the collaboration focuses on the deposition of organic printed photodetectors onto a plastic organic thin-film transistor backplane, to create a flexible sensor with a 40x40mm active area, 375um pitch (175um pixel size with 200um spacing) and a 94x95 = 8 930 pixel resolution – see Figure 1.
Fig. 1: Plastic image sensor prototype (Isorg / Plastic Logic)
Biometrics applications using fingerprint and palm recognition could use printed electronics to substitute the typical CMOS-based sensors with thinner and lighter organic solutions. Current developments yield a pixel resolution of 50um. Such approaches could also enable the design of large scanning surfaces to substitute CCD line scanners in office equipment, yielding faster, lighter and thinner document scanners. So far in this field, a pixel resolution of 80um has been achieved for a 300 dpi document scanning resolution.