A silicon-based multi-sensor chip for monitoring of fermentation processes

This paper describes the design and characterization of a silicon‐based sensor chip for monitoring of fermentation processes. The sensor chip consists of three sensors using different transducer principles. A capacitive electrolyte‐insulator‐semiconductor (EIS) field‐effect structure with Ta2O5 as gate material was utilized as pH sensor. An electrolyte conductivity sensor was realized by measuring the impedance between two interdigitated electrodes (IDE). A platinum thermistor was included for temperature measurements. The EIS sensor was integrated into a bioreactor and successfully used for an inline pH measurement. The layout of the IDE has been optimized with respect to a high cell constant and a wide detectable conductivity range. The integrated platinum thermistor allowed for temperature compensation of the electrolyte conductivity measurement.