DEVELOPMENT AND APPLICATION OF A NEW ENZYME SENSOR TYPE BASED ON THE EIS-CAPACITANCE STRUCTURE FOR BIOPROCESS CONTROL

New biosensors were developed by immobilizing enzymes on simple EIS (E lectrolyte Insulator Semiconductor) layer structures. These EIS-struct ures produced by means of semiconductor technologies are either pH-(Si /SiO2/Si3N4/Ta2O5 layers) or pF-sensitive (Si/SiO2/Si3N4/LaF3 layers). A schematic of the layered structure is shown in Fig. 1. The basic pr inciple for measurements with the modified EIS-layer structures is the change in capacitance in dependence on the concentration of H+ or F- ions. Measurements were made by using a C/V-measuring instrument in a ''constant charge mode''. These biosensors as well as a reference elec trode were integrated into an FIA-system (Flow Injection Analyser) and the concentrations of penicillin and urea (with pH-sensor) and H2O2 a nd glucose (with pF-sensor) were determined.