Development and application of a new enzyme sensor type based on the EIS-capacitance structure for bioprocess control

Abstract

New biosensors were developed by immobilizing enzymes on simple EIS (Electrolyte Insulator Semiconductor) layer structures. These EIS-structures 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 principle 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 electrode were integrated into an FIA-system (Flow Injection Analyser) and the concentrations of penicillin and urea (with pH-sensor) and H2O2 and glucose (with pF-sensor) were determined.