Figure 5.

Schematic illustration of an electrochemical immunosensor; (A) a luminophore undergoes redox reaction in the electrodes with the co-reactant, producing photons that can be detected by the photodetector (e.g., a complementary metal–oxide–semiconductor (CMOS) and charge coupled device(CCD)); (B) similar to a common glucose sensing biosensor, electrons can be produced via enzyme catalytic reaction (e.g., peroxidase), which is labeled with the antibody in the presence of the substrate (e.g., hydrogen peroxide). Graphene, a carbon allotrope (in the form of honeycomb), was recently used as a supporting matrix for enhancing electrical performance.