Flexible Calorimetric Gas Sensors for Detection of a Broad Concentration Range of Gaseous Hydrogen Peroxide: A Step Forward to Online Monitoring of Food-Package Sterilization Processes

In this study, flexible calorimetric gas sensors are developed for specific detection of gaseous hydrogen peroxide (H2O2) over a wide concentration range, which is used in sterilization processes for aseptic packaging industry. The flexibility of these sensors is an advantage for identifying the chemical components of the sterilant on the corners of the food boxes, so-called cold spots, as critical locations in aseptic packaging, which are of great importance. These sensors are fabricated on flexible polyimide films by means of thin-film technique. Thin layers of titanium and platinum have been deposited on polyimide to define the conductive structures of the sensors. To detect the high-temperature evaporated H2O2, a differential temperature set-up is proposed. The sensors are evaluated in a laboratory-scaled sterilization system to simulate the sterilization process. The concentration range of the evaporated H2O2 from 0 to 7.7% v/v was defined and the sensors have successfully detected high as well as low H2O2 concentrations with a sensitivity of 5.04 degrees C/% v/v. The characterizations of the sensors confirm their precise fabrication, high sensitivity and the novelty of low H2O2 concentration detections for future inline monitoring of food-package sterilization.