APPLICATION OF SCREEN-PRINTED ELECTRODES IN BIOCHEMICAL-ANALYSIS

Screen printing technology has been used for the production of amperometric devices. The materials chosen were conventional thick film materials, (i.e. Al2O3-ceramic substrates and pastes of different composition, fired at 850-degrees-C). The working and the auxiliary electrodes were made by screen printing Pt paste, the connecting lines and reference electrodes in the three electrode system by printing AgPd paste. Enzymes were immobilised on the working electrodes either by cross-linking with glutaraldehyde or by adsorption in a screen printable graphite based paste. For both procedures the composition of the immobilisation matrix had to be optimised for each enzyme. It was observed that the achievable lower detection limits and standard deviations between different enzyme electrodes were lower when the enzymes were cross linked with glutaraldehyde, whereas the sensitivities were comparable for both immobilisation techniques and were improved further by the application of additional membranes acting as diffusion barriers. Stabilities of the enzyme electrodes were improved by electrode treatment (such as silanisation of the electrodes), optimisation of the measuring conditions an composition of the storage buffer.