How Temperature Data Loggers Are Used in Cold Chains
When the COVID-19 vaccines descended like avenging angels to rescue us from the pandemic, most of the general public knew three things about them. First, we knew they had been developed in record time. Second, we knew that clinical trials pointed to near-miraculous effectiveness.
Third, we knew that the vaccine had to be kept not just cold but beyond cold.
The first vaccine to market, the mRNA vaccine developed in partnership between American pharmaceutical giant Pfizer and German pharma giant BioNTech, was particularly sensitive to heat.
Pfizer has since revised its recommendations, having discovered the vaccine to be stable between -10 and -15 degrees Celsius. Most hospitals and clinics have freezers that get that cold. But when it was released, Pfizer recommended storage temperatures of a punishing -15 to -25 degrees Celsius. Antarctica has had warmer winters than that.
The third vaccine to market in the US, made by Johnson & Johnson, was considered a game-changer. Not because it was more effective—clinical trials suggested it was the least effective. Rather, it was the least sensitive to temperature, making it logistically easier to get the vaccine to remote places.
This vaccine rollout has cast into stark relief the importance of a cold chain in the pursuit of public health–and the role of temperature data loggers in maintaining those cold chains.
What Is a Temperature Data Logger?
A temperature data logger is a simple digital device that records data about the temperature in the vicinity of the device. It time-stamps the data, so you can preserve the record of the exact temperature within the device’s range at any given time when the data logger is in operation.
How does it do this? A temperature data logger performs its function through the interaction of three basic components:
1. A thermometer.
To record the temperature, you need to be able to detect the temperature. Temperature data loggers use a range of digital heat sensors. They might be calibrated to detect basic heat, like gradations of room temperature; or they could be sophisticated thermometers designed to detect extreme temperatures, like deep freeze or molten metal.
2. A microprocessor.
The microprocessor makes the temperature data logger into a simple computer. This component takes information from the thermometer and renders it into a digital format that can be read by humans. Based on the resolution capability of the microprocessor (measured in bits), the microprocessor may be able to measure a huge range of temperatures or tiny variations within a small temperature range.
3. A storage drive.
A hard drive, flash drive, or SSD, data loggers include some way to store the data that the microprocessor interprets.
Once the data is recorded on the storage drive, it can be retrieved in a variety of ways. Early temperature data loggers offered access to the data on the drive by hardware connections like USB.
Newer data loggers connect to other devices or to the cloud through wireless technology like WiFi or BlueTooth, eliminating the need to manually port into the device. The most sophisticated modern data loggers are IoT (internet of things) devices that push data directly to the Cloud. In some cases, the software can collate the data automatically into compliance-ready reports.
Dickson’s guide to temperature data loggers explains more about how they’re used in different industries.
What Is a Cold Chain?
Remember the Pfizer/BioNTech vaccine, which must be kept at sub-glacial temperature to keep it from spoiling?
How do you know that any given dose of that vaccine has been diligently kept at the required temperature, at every stage of its life from the factory to the patient’s arm?
It’s an important question. After all, the patient’s life may depend on acquiring an immune system defense to a deadly disease through the vaccination.
The answer is a cold chain—a logistical process that documents the temperature condition of a product at every stage of its life—from the factory to storage, to transit, to additional storage, to the point of consumption.
Validation of an effective cold chain is required in many heavily regulated industries where the storage temperature of the product impacts the safety or efficacy of the product.
The pharmaceutical industry, with its temperature-sensitive drugs and vaccines, is an obvious example. Another example is the food-production industry, where overheating products can lead to a public health crisis.
In the US, both the food and pharma industries answer to the US Food and Drug Administration (FDA). To maintain compliance with FDA regulations, organizations in these industries must validate their cold chains. This is part of quality assurance—proving to the public and to the regulators that your products have been handled in a way to protect public health and safety.
How Temperature Data Loggers Are Used in Cold Chain Logistics
We have now defined the problem—validating the storage and handling temperature of a heat-sensitive product. We have also defined the solution—temperature data loggers to the rescue.
Organizations in the food, pharma, and other industries install temperature data loggers at every stage of their logistics to validate the cold chain. The data logger produces a record of the ambient temperature. Does a vaccine need to be stored below -5 degrees Celsius? Check the data logger to make sure the temperature never rose above that threshold in the environments where the vaccine was stored or transported.
Tracking the temperature of a cold chain includes installing data loggers in a variety of places, including:
- The factory where the product was manufactured.
- Warehouses where the product is stored.
- Transport containers, including refrigerated containers, are used to transport the product by land, sea, or air.
- Retail outlets where the product will become available to consumers.
As you can see, preserving a cold chain requires multiple temperature data loggers. Oftentimes, multiple data loggers are needed for one location. A large warehouse may vary in temperature due to the position of doors, windows, machinery, or simply vertical clearance—a warehouse may be warmer near the ceiling than near the ground. Warehouse managers must often perform a procedure called temperature mapping—installing multiple data loggers throughout the facility to track temperature differences and adjust the climate control accordingly.
Sophisticated IoT data loggers that communicate with the Cloud provide another avenue of quality control within a cold chain. If the cold chain fails at any point—say, a facility or container becomes—a basic temperature data logger can tell you that the failure happened and when.
The inventory might be useless and have to be discarded. After all, it got too hot. It might no longer be safe to consume. This protects public health, safety, and regulatory compliance, but the organization also has to eat the cost of the spoiled inventory.
By contrast, IoT temperature data loggers can not only record when a cold chain failure happens—it can sound the alarm. The best IoT data loggers can notify logistics managers of the cold chain failure in real time—by email, SMS, push notification, etc. This might give the managers enough notice to act quickly, correct the issue, and save the cold chain, preventing loss of inventory while still protecting public health.
Cold chains are actually a modern miracle. Consider—nearly everyone in our society goes to the grocery store or the pharmacy without serious fear that consuming those products will make them sick or endanger their life. We owe that confidence to cold chains. And we depend on temperature data loggers to maintain those cold chains. In temperature data loggers we trust.
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