3. Immobilization procedures

The ligand can be immobilized on the solid support of the biosensor by various methods, such as adsorption, covalent coupling, encapsulation, etc. The aim of any immobilization method is to retain the maximum activity of the biological ligand on the transducer surface. The selection of an appropriate immobilization method depends on the nature of the biological ligand, the type of transducer used, the physico-chemical properties of the analyte and the operating conditions of the biosensor [6] . The two most commonly used methods are adsorption and covalent coupling.

• Physical adsorption of a ligand based on attractive Van der Waals forces is the oldest and simplest method of immobilization. It requires no chemical modification of the ligand, and allows the biosensor to be regenerated....