Experimental extraction of stern-layer capacitance in biosensor detection using silicon nanowire field-effect transistors

Accurate diagnose of a disease in the early stage is critical to treat the disease properly. To this end, a multitude of biosensors with advanced technologies have been developed to detect the number of biomolecules precisely. In this work, we propose a method for extracting the Stern layer capacitance (C_stern) using the experimental data of silicon nanowire ion-sensitive field-effect transistors (ISFETs) to help improve the accurate detection of target molecules. The proposed method was applied to both pH and virus sensing scheme, and the C_stern value of pH and a virus were extracted as 32 and 26 μF/cm², respectively. These findings indicated that the extracted C_stern was affected by the size of the ion and protein, which also was verified by a computer-aided simulation. These insights would be useful in the development of charge-based ISFET biosensors.