Time and temperature: technology marches on for critical detection of temperature change and elapsed time.

Author:Kenny, Jack
Position::FRONT Row

Time sensitive labels have been around for a couple of decades. Schools and businesses have been utilizing them over the years as identity badges for visitors. Depending on the nature and performance of the label's chemistry, such badges can expire after a day or within a few hours. Since the September 11, 2001, attacks in the United States, the security badge business has been quite healthy.

Technology has taken time sensitivity far beyond ID badges. About a decade ago a New Zealand company pioneered RipeSense, a label for fruit and vegetable packages that monitored the gases emitted by the contents and indicated the stages of ripeness via color changes on the label. This year, Norway's Thin Film Electronics hopes to market its Smart Sensor labels. As noted in December 2013 by L&NW Editor Steve Katz, the product is designed to monitor the freshness of perishable goods and is manufactured from printed and organic electronics.

Food freshness, however, is still monitored largely by the consumer's physical senses in conjunction with the ubiquitous sell-by date. Mold on bread and dairy products is a good indicator that the window for ingestion has closed. Milk that has turned is easy to detect by its aroma. Old corn flakes simply do not crunch.

Accurate timing mechanisms for packaging have been costly. RFID is reliable, but its growth has been impeded by the expense of production. Labels that change color can be affected by temperature, which is a major cause of instability and spoilage in many food products.

Fritz Braunberger believes that his company, Vision Works IP of Sequim, WA, USA, has a solution for determining accurate product Shelf life. It's called TimeDot, a printed electronics label whose measurement of elapsed time is independent of temperature change.

"Color-changing labels (CCLs) have been around for some time and have been used to indicate when critical dates have been reached or exceeded within the various industries," notes Braunberger. "The accuracy of such labels has always been dependent upon ambient temperature swings. So their use has been restricted to applications where conditions could be predicted. Their accuracies were only as good as the predictions.

"CCLs change color over time and find applications in everything from wine bottles to vaccine vial monitors and from cold chain management of perishables to hospital reminder wristbands. CCLs serve as an active means to indicate expiration, action-required date or...

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