> refrigeration. Samples being shipped to the lab and reagents shipped out to clinics were both temperature sensitive. Providers had to verify that these materials had stayed adequately cold throughout shipping and handling, [...] Moreover, Stevens imagined that these sensors would be in continuous communication. There's a lot of overlap between this application and personal area networks (PANs), protocols like Bluetooth

I like the low-fi solution personally:

https://www.ipack.com/warmmark-temperature-indicator-short-r...

https://www.ipack.com/coldmark-temperature-indicator-10c-50f...

That will tell you if the item is spoiled, not alert you that it is on its way to being spoiled. Very different use cases and outcomes.