Fig. 4.

Schematic images of glucose biosensors based IO: a) A schematic illustration and SEM image of the enzymatic ZnO IOs electrode b) schematic illustration and SEM image of ZnO IOPCs modified FTO electrode c) a schematic diagram and SEM image of IOs conducting hydrogel films d) A schematic illustration and SEM image of TiIOs film. Scale bar represented by 200 nm. Copyright 2013, AIP Publishing. Reproduced from Ref. [101]. Copyright 2014, Elsevier. Reproduced from Refs. [6]. Copyright 2012, Royal Society of Chemistry. Reproduced from Ref. [102]. Copyright 2008, John Wiley and Sons. Reproduced from Refs. [107]. IO: inverse opal, SEM: scanning electron microscopy, ZnO: zinc oxide, IOPCs: Inverse opal photonic crystals, FTO: fluorine-doped tin oxide.