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Luminescence oxygen sensors

Identification

Key words Oxygen sensors, luminescence, quenching effect
Latest version 2012/03/03
Completed by UTCN

How does it work?

Primary objective oxygen detection.
Working principle The presence and concentration of oxygen is the main cause of food spoilage, thus measurement of residual oxygen can be very important in many applications.

Luminescence is the emission of light from a cool object, resulting from chemical reactions, electrical energy, subatomic motions, etc. Luminescence based oxygen sensors rely on an active component – a luminescence indicator dye embedded in a thin membrane, usually a solid polymer matrix [3]. The luminescence of the indicator is quenched (extinguished) by molecular oxygen present in the packaging headspace which penetrates the sensitive coating by diffusion; the decrease of luminescence can be directly linked to the partial pressure of the oxygen [1]. This type of sensors are non-toxic and can be either attached to the package in the headspace or can be formulated as inks. The main reason for using luminescence based oxygen sensors instead of other methods is their simplicity and high sensitivity to oxygen concentration changes and also the fact that they do not consume oxygen or generate toxic byproducts in their sensing process. Luminescence quenching can be measured based on the luminescence intensities or on the lifetime of the luminescence, both of them decreasing after quenching [4].

Luminescence-based oxygen indicators have the following advantages [5]:

  • provide non-invasive, real time, passive, in-situ monitoring
  • neither oxygen nor dye are consumed during the photochemical reactions involved
  • no by-products are generated and the operation can be repeated
Images
Additional effects
Important process parameters sensor-support system, temperature control, reversibility of response
Important product parameters temperature of the matrix where the sensor is embeded, aggregation state (liquid, solid, gas)

What can it be used for?

Products Luminescence based oxygen sensors can be applied to any closed packaging type with a headspace containing gas or liquid.

They can be used for oxygen measurement for blister packs, pouches and bottles, and permeation/oxygen ingress testing for closures and films [1][6].

Operations Packaging (permeation/oxygen ingress testing for closures).
Solutions for short comings More performant packaging for longer shelf-life of food products.

What can it NOT be used for?

Products Luminescence based oxygen sensors are restricted to transparent, semi-transparent and translucent packaging [1].
Operations This technology only applies to packaging , even in case they need to be pasteurised.
Other limitations One limitation of this type of sensors is the temperature dependency of the quenching process (measurements are accurate at ambient temperature). Also, the materials used must be very sensitive and performant in order to prove their suitability to be used in commercial intelligent packaging applications [1].
Risks or hazards No risks or hazards (according to existing references in January 2012).

Implementation

Maturity Luminescence based oxygen sensors are available on the market.
Modularity /Implementation It can be inserted in an existing production line.
Consumer aspects No consumer concerns have been reported.
Legal aspects Please check local legislation.
Environmental aspects Energy efficient (short analysis time).

Further Information

Institutes ETH Zurich, University of Strathclyde, University of Toronto - Chemistry, University of Florida - ABE
Companies OxySense, Luxcel, PreSens, Ocean Optics
References
  1. Joseph Kerry, Paul Butler, Smart Packaging Technologies, Wiley, 2008.
  2. R. Ramamoorthy, P. K. Dutta, S. A. Akbar, Oxygen sensors: Materials, methods, designs and applications, Journal of materials science 38, 4271 – 4282, 2003.
  3. Xin Lu and Mitchell A. Winnik, Luminescence Quenching in Polymer/Filler Nanocomposite Films Used in Oxygen Sensors, Chem. Mater. 13, 3449-3463, 2001.
  4. Andrew Mills, Oxygen indicators and intelligent inks for packaging food, Tutorial review, Chemical society reviews, 2005.
  5. Dr. Devinder Saini, Real-time Oxygen Monitoring for Modified Atmosphere Processing using the OxySentry System, www.oxysense.com, 2008.
  6. http://www.oxysense.com/page/How-It-Works.aspx
  7. Dieval Jean-Baptiste; Vidal Stephane; Aagaard Olav, (2011) Measurement of the Oxygen Transmission Rate of Co-extruded Wine Bottle Closures Using a Luminescence-Based Technique , Packaging Technology and Science 24,375-385.



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Created by RusVUTCN on 3 March 2012, at 09:15