Activatable time-temperature indicator
AssigneeLifeLines Technology, Inc.
InventorHimangshu R. Bhattacharjee
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Abstract
An activatable time-temperature indicator consists of an oxygen-sensitive reaction product of a triarylmethane dye and a decolorant that is coated on a substrate and covered by an oxygen barrier. Optinally, an oxygen-permeable layer is between the coating and the oxygen barrier. The indicator is activated by removing the oxygen barrier. Following this activation step, a progressive color development occurs at a rate that increases with temperature. The indicator is useful for monitoring the freshness of perishable products, particularly those stored at sub-ambient temperature.
Claims20
An activatable time-temperature indicator comprising:
- (a) a substrate on which is a coating of an oxygen-sensitive reaction product of a triarylmethane dye and a decolorant for the dye and
- (b) a removable oxygen barrier over the coating.
A method of measuring an incremental time-temperature exposure with an activatable time-temperature indicator comprising a substrate on which is a coating of oxygen-sensitive reaction product of a triarylmethane dye and decolorant for the dye and a removable oxygen barrier over the coating, which comprises the steps of:
- (a) removing the oxygen barrier from the indicator to expose the indicator to ambient oxygen, thereby activating it,
- (b) measuring the reflectivity of the indicator at a specified wavelength,
- (c) measuring the reflectivity of the indicator at the specified wavelength after an incremental time-temperature exposure, and
- (d) calculating the incremental time-temperature exposure by using a pre-established relationship between a change in reflectivity of the indicator and time-temperature exposure.
A method of measuring an incremental time-temperature exposure of a perishable article by
- (a) applying to the article an activatable time-temperature indicator comprising a substrate on which is a coating of an oxygen sensitive reaction product of a triarylmethane dye and a decolorant for the dye and a removable oxygen barrier over the coating,
- (b) removing the oxygen barrier from the indicator to expose it to ambient oxygen, thereby activating it,
- (c) measuring the reflectivity of the indicator at a specified wavelength,
- (d) measuring the reflectivity of the indicator at the specified wavelength after incremental time-temperature exposure, and
- (e) calculating the incremental time-temperature exposure by using a pre-established relationship between a change in reflectivity of the indicator and time-temperature exposure.
Dependencies are inferred from the claim text.