Binding of a molecule to a molecular receptor is sensed using a transistor having a gate located at a binding site. The channel conductance of the transistor is modified by a charge associated with the molecule when the molecule binds with the molecular receptor. A modified electrical characteristic of the transistor which results is sensed to sense the binding event. Electric field enhancement is provided by applying a voltage to the gate. A second sensing transistor can be coupled to the sensing transistor to form a differential pair. The differential pair allows for enhancing and sensing of differential binding events.