Nanotube Field-Effect Biosensor: Threshold-Voltage Shift Simulator

This simulation models a real transduction mechanism used in next-generation label-free biosensors: a carbon-nanotube or graphene field-effect transistor (FET) functionalized with receptor molecules and operated as a liquid-gated device. Target molecules bind receptor sites following genuine Langmuir kinetics, adding surface charge that is screened by the electrolyte's mobile ions over a real Debye length. That screened charge shifts the channel's threshold voltage, and the resulting drain current — computed from the standard FET square-law equation — is the sensor's actual electronic signal. Adjust target concentration, receptor affinity, ionic strength and gate bias to see how each independently real physical parameter shapes the live binding curve and current readout.