A dual function electro-optical silicon field-effect transistor molecular sensor†
We propose and demonstrate an approach that utilizes field-effect transistors (FETs) for the real-time detection of interactions between molecules. In this approach, FET-based sensors utilize two unique functions, high charge sensitivity and high photon responsivity. We use these transistors to detect the changes in molecular charge and photon absorption associated with the binding of antibody and antigen molecules. For comparison with enzyme-linked immunosorbent assay (ELISA), we adopt an ELISA sandwich structure immobilized on the FET surface to detect neutrophil gelatinase-associated lipocalin (NGAL). Using this technique, we detect NGAL quantitatively with a sensitivity of 0.1 pg mL−1 and <1 pg mL−1 based on charge sensing and oxidized TMB absorption detection, respectively. We further show that this platform performs great for diagnostic applications of biosensors.