ISFET Based DNA Sensor: Current-Voltage Characteristic and Sensitivity to DNA Molecules

Dependency of both source-drain current and current sensitivity of nanosize ISFET biosensor vs. concentration of DNA molecules in aqueous solution theoretically is investigated. In calculations it is carried out effects concerning charge carriers distribution in current channel and concerning carriers’ mobility behavior in high electrical fields in the channel. The influence of DNA molecules on the work of ISFET biosensors is manifested by a change in the magnitude of the gate surface charge. Starting with fairly low concentrations of DNA, ISFET sensors respond to the presence of DNA molecules in an aqueous solution which is manifested by modulation of channel conductance and therefore the source-drain current changes of the field-effect transistor. It is shown that the current sensitivity with respect to concentration of DNA molecules linearly depends on the source-drain voltage and reaches high values.