Microfluidic chips have been applied in BC diagnostics for quick and standardized detection of specific biomarkers like: ER, PR, HER2, and Ki67 (proliferation marker) on fixed tissue samples (Cho et al., 2018; Aimi et al., 2019), and for early detection of circulating cancer cells (Fang et al., 2017). The gene discussed is ERBB2; the disease is cancer.