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Time and Temperature



Technology marches on for critical detection of temperature change and elapsed time.



Published June 2, 2014
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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 other critical date.

“The new TimeDot technology features a timing mechanism whose temperature sensitivity can be designed to include temperature independence. Because the timing mechanism can be accurate independent of ambient temperature swings, across a wide variety of environments, the applicability of the technology is vast. Time periods can range from hours to years and passage of time can be indicated by a color or graphical change.”

Upon expiration of the product, he adds, a sudden change in the label’s appearance takes place.

TimeDot is manufactured by laminating layers of rollfed materials. The label may be a few thousandths of an inch thick and as small as 1/8" in diameter. Vision Works has been awarded several US patents on the technology.

The application has potential use beyond food, particularly in medical and pharmaceutical fields. Medication non-compliance – failure by patients to take prescribed drugs – was estimated two years ago to result in 125,000 deaths a year and cost $289 billion in the US alone, according to the Annals of Internal Medicine. Among the recommendations in the study was this: Switch to better packaging.

Braunberger says that such packaging should be designed to guide and prompt patients to take medications as prescribed. TimeDot can be used on blister packaging to alert the patient that a dose is due at a certain time. “To date these package designs have been limited to printed graphics, arrows, dates and charts,” he observes. “The TimeDot technology includes an active means of alerting the patient to an administration date. Within this new package design and by merely ejecting a pill from the blister pack, the patient activates an adjacent cell which in turn changes color when the next pill is due.”

The technology also can be put to use in packaging for vaccines. Vision Works has designed a label based on the TimeDot technology that would replace what Braunberger calls “existing obsolete technology.” The new electrochemical based vaccine vial monitor would feature an increase in accuracy and can display both cumulative exposure to heat and peak exposures.

The company has developed a wearable band to remind caregivers of infants in underdeveloped countries when to return to the hospital for follow-up vaccinations. Different diseases require different vaccinations at staggered intervals as much as 36 weeks apart. The TimeDot band, placed around the child’s ankle, has separate zones that change color at different time periods and correspond to the due date of a vaccine.

The technology has been explored by pharmaceutical manufacturers who produce samples of medications for medical and dental offices. Such samples have a wide range of expiration dates, and an accurate time-lapse label would give a clear indication that the drug is still viable.

An outgrowth of TimeDot is BabyDot, a label that changes color when stored breast milk is no longer safe for infants to drink. The label is applied to the milk container at harvest time, and changes color across a bar graph as the milk ages. Human milk is highly sensitive to temperature, so the BabyDot label changes color at the same rate as the milk spoils.

Timestrip, based in Cambridge, England, has been manufacturing labels to monitor temperature and elapsed time for several years. The company is active in the healthcare, life sciences and food industries, among others.

One popular product is TimestripPlus, which shows whether a temperature breach has occurred and shows the cumulative amount of time during which a product was exposed to a higher temperature. The liquid inside the label moves across the window for as long as a product is held outside cold storage, but stops when it returns to below 8°C/46°F. It is well known that the “last mile” of the cold chain – when prescriptions leave the hospital pharmacy – is difficult to control, and a label such as this could help to assure compliance.

Timestrip Seafood labels monitor the rising temperature of fresh seafood in reduced oxygen packaged seafood, where Clostridium botulinum toxins can develop above 3.3°C/38°F. Timestrip also produces labels to monitor temperatures in fresh produce, airline catering, school meals, home delivery diets, food retailing, and restaurants.

Connecticut-based Omega Engineering, a major manufacturer of products for measurement and control of temperature, humidity, pressure, and other physical factors, produces both reversible and non-reversible temperature labels. These are heat-sensitive indicators sealed under transparent heat-resistant windows.

A reversible temperature label can change back and forth as needed to provide an indication of the present temperature. These can be re-used. A non-reversible temperature label is a one-time usage product showing that a specified temperature has been reached. The label may be examined at any time to determine if the desired temperature has been obtained. The center of the indicator circle on a non-reversible label will turn black at the temperature rating shown on the label. The exposed label can be made part of the permanent product record by removing it and affixing it to a service report.




The author is president of Jack Kenny Media, a communications firm specializing in the packaging industry, and is the former editor of L&NW magazine. He can be reached at jackjkenny@gmail.com.


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