Configurations used in the design of screen-printed enzymatic biosensors. A review

Different thick-film biosensor configurations designed during the last decade are revised. These planar configurations are classified in three groups: (a) multiple-layer deposition (biological deposition by hand or electrochemically), (b) screen-printing of composite inks or pastes using two or more steps (biological deposition by screen-printing), (c) one-step deposition layer or biocomposite strategy. Different enzyme immobilization procedures corresponding to these configurations are also revised. These procedures consist mainly of enzyme adsorption onto transducer surface, biological immobilization by cross-linking in a glutaraldehyde layer, and physical, electroor UV-polymerization entrapment. Immobilization into the bulk of different carbon-based inks or pastes is also presented.