Visual Indicators of Biospecimen Time-Temperature Exposure


Most biospecimens, vaccines and biological therapeutics require cold storage, necessitating cold chain tracking. If these specimens undergo unknown freeze thaw cycles, it can damage the sample or inactivate critical components. When the stakes are high, paper trails aren’t reliable enough for cold chain tracking purposes; empirical evidence of proper handling is a necessity. While electronic tracking devices work at all temperatures, they are relatively expensive and are not practical for monitoring down to the resolution of individual vials. Physical or chemical-based visual indicators are relatively inexpensive and may be viable at the individual vial level, however, current indicators cannot sense “exposure” to temperatures between -18 °C and -70 °C. Further, they are not readily customizable for desired time-temperature ranges.


Researchers at the Biodesign Institute of Arizona State University have developed a novel solution that can be attached to biospecimens which functions as a visual indicator of time-temperature exposure. This solution distinctly loses its color when exposed to time and temperature conditions that exceed a particular design threshold. It can be designed such that it transitions, in a time-dependent manner, to a colorless solution upon exposure to conditions that exceed allowable storage and handling requirements.


This solution facilitates empirical biospecimen storage and handling tracking during initial processing and over the entire life of an archived or biobanked specimen.


Potential Applications

• Indicators of Time-Temperature Exposure in storage, processing and cold chain tracking:

o Fresh biospecimens

o Vaccines

o Biological therapeutics

o Biobanked samples


Benefits and Advantages

• Works with any type of tissue or fluid biospecimen/sample/composition

• Can monitor exposure to temperatures between 0 and -33 °C and 0 and -76°C

• Ultra-rapid visual indication of sample integrity at the individual vial level

• Indicates exposure beyond a tightly pre-defined time interval at a given temperature

• The solution does not physically interact with the specimen – it can be stored within the cap or outer perimeter of the vials

• The chemical reaction for color transition is halted indefinitely by freezing, but restarts upon thawing, regardless of the number of prior freeze-thaw cycles

• Complex rate law-based prediction of reaction kinetics facilitates custom-designed cold-chain monitoring solutions

• The reaction does not involve freeze-thaw sensitive biomolecules such as enzymes

• Estimated cost of raw materials: < $0.05 for chemicals, < $0.10 for self-contained device

• Eliminates sample consumption and/or disturbance as part of the verification process

• Eliminates sole reliance on written records as a means of documenting integrity


For more information about the inventor(s) and their research, please see

Dr. Borges' departmental webpage


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Chad Borges Kazi Waheeda

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