Nanomaterial-based opto-electrical oxygen sensor for detecting air leakage in packed items and storage plants

A novel nanomaterial-based sensor has been fabricated for detecting air leakage in packaged foods, medical devices and inert gas storage plants. The sensor involved ion-pairing of methylene blue with dodecyl sulphate to produce a water- insoluble form of dye, which along with nano TiO₂ as a sensitiser, is used to create an UV-activated oxygen-sensitive indicator that can be printed on a variety of hydrophobic polymers. The developed sensor not only gives colourimetric indication of air leakage but also provides measurable change in electrical behaviour on air exposure. It bleached quite rapidly and became white in colour (with in a minute) under UV light and recovered its original blue colour when exposed to air. The rate of recovery of the original colour of the sensor is proportional to the ambient oxygen level. The sensor has also been connected to an electrical circuit to generate signals and it is useful to produce an alarm on entering the air into the evacuated or inert gas storage plants. Such a combination of materials and processing offers the potential of producing a low-cost, sensitive and reusable oxygen sensor.