Even though the sensitivity of this newly introduced sensor is not as low as the commercially available ELISA kits, it can be argued that the HER-2 biomarker does not require such low LODs, as its physiological range is between 2.0 and 15 ng mL−1 for healthy individuals, while it rises to a range between 15 and 75 ng mL−1 in women with breast cancer [48,49]. The gene discussed is ERBB2; the disease is breast cancer.