Highly sensitive detection of epidermal growth factor receptor expression levels using a capacitance sensor

We developed a capacitance sensor with parallel plate geometry to measure epithermal growth factor receptor (EGFR) expression levels on cell membrane in real-time. We first proved correlations between capacitance changes and cell numbers settled down between electrodes, and then observed capacitance changes elicited by interactions between EGFR on membrane and EGF proteins in real time. Consequently, we confirmed that the EGFR expression levels of varied typed cells were successfully quantified. This approach can effectively distinguish differences of EGFR levels of cancer cells and normal cells in real-time. Also, up to 600% sensitivity enhancements and around 2.2 h on average sensing time saving were achieved by using the capacitance sensor over a conventional immunoassay technique. Such a capacitance biosensor can be extended to broad fields where the receptor-antibody reactions, the receptor-virus reactions or DNA hybridizations are involved.