Inkjet-printed O₂ gas sensors in intelligent packaging

Area of Science:

• Materials Science
• Analytical Chemistry
• Food Science

Background:

• Smart packaging requires real-time indicators for product quality.
• Modified atmosphere packaging (MAP) relies on controlled gas environments to prevent degradation.
• Colorimetric sensors offer a visual, accessible method for monitoring environmental changes.

Purpose of the Study:

• To develop an inkjet-printed colorimetric sensor for oxygen detection in smart packaging.
• To assess the sensor's performance, stability, and response to environmental factors.
• To demonstrate the sensor's practical application in monitoring packaged food products.

Main Methods:

• Inkjet printing of a membrane incorporating toluidine blue, glycerol, and hydroxypropyl methylcellulose.
• Photoreduction of toluidine blue using UVC light and SnO2 nanoparticle ink.
• Colorimetric analysis of oxygen exposure using a digital camera.
• Evaluation of sensor response under varying humidity and temperature conditions.

Main Results:

• The sensor remained stable in the absence of oxygen.
• High relative humidity (>60%) and temperature significantly affected the reoxidation process.
• Refrigeration at 4°C enhanced sensor stability.
• The sensor successfully indicated oxygen ingress in packaged ham over 48 hours.

Conclusions:

• Inkjet-printed toluidine blue membranes serve as effective UVC-activated colorimetric oxygen sensors.
• The sensor's functionality is influenced by humidity and temperature, requiring controlled conditions for optimal performance.
• This technology offers a promising solution for visual oxygen indication in smart food packaging applications.