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. Author manuscript; available in PMC: 2013 Aug 1.
Published in final edited form as: J Neural Eng. 2012 Jul 12;9(4):046014. doi: 10.1088/1741-2560/9/4/046014

Figure 4.

Figure 4

(a) SEM image of the large-, medium- and small-pixel arrays on a 4-inch wafer. (b) Optical microscope image of a medium-size pixel showing the central active electrode (cathode) and local concentric return electrode (anode). Diodes 1, 2 and 3 are connected in series; with the n+ and p+ regions of diode 1 indicated in the figure. Under illumination, photocurrent flows into the central active electrode, through the series-connected diodes, and flows out of the concentric return electrode.