Flexible polyimide-based calorimetric gas sensors for monitoring hydrogen peroxide in sterilisation processes of aseptic filling machines

The sterilisation of beverage cartons prior food filling is a mandatory process to avoid microbial recontamination of the sensitive products. In order to monitor the sterilisation medium, gaseous hydrogen peroxide (H2O2) is used. Different types of gas sensors have been developed, recently. The sensor principle is based on a calorimetric differential set-up of two temperature sensors, one of them passivated and one additionally activated by a suitable catalyst. At the catalytically activated temperature sensor the exothermic decomposition of H2O2 will be forced. The temperature difference between both temperature sensors is in correlation with the present H2O2 gas concentration. The latest sensor generation is based on a flexible polyimide-based substrate. This type of substrate enables different advantages, improved adaptation into the beverage packages, and enhanced sensor characteristics such as high sensitivity and low response time. In combination with a wireless transmitter, inline-monitoring of the H2O2 concentration during the fast package sterilisation process could be established.