<jats:title>Abstract</jats:title><jats:p>Breast cancer has been reported to be high in its incidence with women, and early identification of breast cancer helps to improve and provide an effective treatment. Tumor markers are active substances; in particular, human epidermal growth factor receptor 2 (HER2) is over‐expressed at the level of 20%–30%. This research work developed a highly sensitive HER2 biosensor on the interdigitated electrode (IDE) by using aptamer as a detection probe. To enhance the analytical performances, aptamer was attached to the gold nanoparticle and immobilized on the IDE through a chemical linker [(3‐aminopropyl)triethoxysilane]. On the aptamer conjugation, HER2 was quantified through current‐volt measurements, and the limit of detection of HER2 was calculated as 1 pg/mL on a linear range from 0.1 to 3000 pg/mL at an<jats:italic>R</jats:italic><jats:sup>2</jats:sup>(regression coefficient) of 0.9657. Further, a selective performance with human serum increased the current responses by increasing HER2 concentrations. Specific experiments with control protein and complementary aptamer sequence failed to enhance the current responses. This HER2 biosensor reflects the occurrence of breast cancer at its lower abundance and helps to identify the associated complications.</jats:p>
