For example, a biosensor design based on a paper electrode and using poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) and rGO composite was made by Kumar et al. [111] for cancer biomarker (carcinoembryonic antigen, CEA)-detection from cancer patient serum samples in the linear range of 1–10 ng/mL. The gene discussed is CEACAM5; the disease is cancer.