An electronic device comprising an optically transparent substrate, a first electrode structure incorporating a channel, said channel being optically transparent and said electrode structure being optically opaque, at least one intermediate layer, and a photosensitive dielectric layer disposed above the at least one intermediate layer, the photosensitive dielectric layer incorporating a trench in a region essentially over said channel, the electronic device further comprising a further electrode, wherein the further electrode is located partially in the trench and partially beyond the trench such that portions of the further electrode that extend beyond the trench are separated from the at least one intermediate layer by the photosensitive dielectric layer.