Thin-film calorimetric H2O2 gas sensor for the validation of germicidal effectivity in aseptic filling processes

In common aseptic filling processes, hydrogen peroxide vapour is a predominantly applied antimicrobial for the inactivation of microorganisms in packages. During this process, the germicidal effectivity of the antimicrobial treatment depends especially on the H2O2 concentration of the gas mixture. For the detection of H2O2 in aseptic filling processes, a novel thin-film calorimetric gas sensor based on a differential set-up of a catalytically activated and a passivated temperature sensing element has been realised in the present work. The sensor device contains two meander-shaped platinum resistances as temperature sensing elements; both have been passivated with spin-coated perfluoralkoxy. As catalytically active materials for the calorimetric gas sensor, palladium, platinum black and manganese oxide particles have been studied in the developed experimental set-up, wherein MnO2 has shown the highest sensitivity of 0.57 °C/% (v/v) towards H2O2. Afterwards, the characteristic of the sensor device with MnO2 particles as catalyst has been examined at various H2O2 concentrations and additionally, the influence of gas temperature and gas flow rate on the sensor signal has been validated in the experimental set-up.