Sheet Image Scanners

In this chapter we review recent progress of organic transistors for sensor applications. Emphasis is put on large-area, flexible pressure sensors suitable for electronic artificial skin and for photodetectors suitable for sheet image scanners. We also describe future prospects of large-area sensors and the other issues. 

The drawback of organic transistor-based sheet image scanners so far, which has been a serious bottleneck in practical applications, has been the slow operating frequency. To overcome this problem we have used a new circuit concept, double... 

In this sheet image scanner, two-dimensional array of sensor cells cover the large area entirely and the data are read electrically, avoiding mechanical scans. We believe that the electronic scan method would be practical, because the manufacturing costs of organic transistors are expected low even for large-areas. 

As far as the sheet image scanner is concerned, another remaining issue is spatial resolution, which is currently 36 dpi. To improve the resolution we must reduce the size of both organic transistors and organic photo detectors. Reduction of device dimensions is not very difficult, but the bottleneck is the size of via interconnections. To reduce the diameter of via holes, we are currently working very hard to replace a CO2 laser with other short wavelength lasers, for example excimer lasers and/or YAG lasers. We believe that 600 dpi would be feasible in the near future. 

Someya, T., Kato, Y, Iba, S., Kawaguchi, H., and Sakurai, T., Integration of organic FETs with organic photodiodes for a large area, flexible, and lightweight sheet image scanners, IEEE Trans. Electron Devices, 52, 2502, 2005. 

The patient should he positioned as comfortably as possible for any examination. For this purpose,special headrests, arm supports (particularly for supporting the arms in the above-head position), and cushionlike supports for the knees are available. The patient must be positioned on a soft surface, which should in addition be heat-insulated. Because most CT scanners are no longer water-cooled but dissipate their heat directly into the room air and because the scanner rooms must normally be fully air-conditioned for this reason, the patient should be covered with a protective sheet. None of the materials employed should contain silicate, glass or other absorbing substances, since the presence of these substances in the scan field can lead to artifacts or increased image noise as a result of beam hardening. 

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