A curved image sensor on plastic foil has been developed for cone beam computed tomography (CBCT) X-ray imaging. The image sensor of about 6 × 8 cm2 size has been built on a thin polyimide foil with an indium gallium zinc oxide (IGZO) backplane and an organic photodetectors (OPD) frontplane. A flexible cesium iodide (CsI) scintillator has been attached to the optical sensor with 480 × 640 pixels of 126 µm size. Dark current density of the OPD was low with less than 10−7 mA/cm2 at −2 V, while an external quantum efficiency (EQE) of about 50% was reached in the visible wavelength range matched to the scintillator output. The image quality of the digital X-ray detector allowed for 3D reconstruction images of a bone phantom on a rotating stage with a lab setup. The curved detector with 32 cm curvature radius opens up the path for very compact CBCT gantries with largely reduced footprint.

Experimentally there appears to be a limit to the size of isolated patterns of electrocatalytic nuclei below which electroless metal deposition does not occur. From a model of electroless deposition on small isolated circular spots we conclude that this inhibition effect is caused by an enhanced supply of oxygen to small patterns due to nonlinear diffusion of dissolved oxygen. Since generally the kinetically determined rate of oxygen reduction is larger than that of oxidation of the reducing agent, the open‐circuit potential of nuclei in small patterns cannot be shifted to a sufficiently negative value at which metal deposition is initiated. At relatively large substrates with a high density of small patterns this so‐called oxygen‐diffusion‐size effect may not be noticed since the supply of oxygen is limited by linear diffusion to an effectively planar substrate.

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